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Sample records for 2mass jhk photometry

  1. JHK photometry of selected Trojan and Hilda asteroids

    NASA Technical Reports Server (NTRS)

    Smith, Dale W.; Johnson, Paul E.; Buckingham, William L.; Shorthill, Richard W.

    1992-01-01

    No entirely satisfactory match has been established between the present JHK photometry of selected Hilda and Trojan asteroids and photometry for both main belt asteroids and laboratory samples. It is noted that while the leading Trojans and Hildas exhibit similar and homogeneous JHK colors, the trailing Trojans appear to be more heterogeneous. Charcoal and magnetite provide the best match in terms of JHK colors.

  2. VizieR Online Data Catalog: JHK photometry of Galactic center stars (Ruelas-Mayorga+ 1993)

    NASA Astrophysics Data System (ADS)

    Ruelas-Mayorga, R. A.; Teague, P. F.

    1997-06-01

    We present K-counts and JHK detailed photometry for a number of stars with K<=+9.0 in three clear regions near the galactic centre. These regions are all located approximately at l~0.0 and at latitudes b~-3.5,-4.0 and 4.5 respectively. Their Cumulative Counts Functions (CCF's) are formed, and with the aid of an exponential disk model for the Galaxy they are separated into disk and bulge CCF. As for the case in Baade's Window (BW) (Ruelas-Mayorga & Teague, 1992A&AS...95..379R) the disk is dominant at bright magnitudes whereas the bulge dominates at the faint end of the CCF. The slope of the bulge CCF is steeper than that for the disk in all three cases corroborating the result obtained for BW. The two colour JHK diagram and the K vs J-K diagram for the three regions show that the stellar population in these areas is similar to that studied in BW by us and by Frogel & Whitford (1987ApJ...320..199F). An average value of E(J-K)~0.42mag for the reddening is obtained, which is somewhat larger than that found for BW (0.27). Finally it is shown that at K<=+9.0, the disk population may be accounted for by those sources with J-K<=+1.6 whereas the bulge population presents values for J-K in excess of +1.6. (2 data files).

  3. VizieR Online Data Catalog: JHK photometry of 4 W51 star clusters (Nanda+, 2004)

    NASA Astrophysics Data System (ADS)

    Nanda, M. S. Kumar; Kamath, U. S.; Davis, C. J.

    2005-03-01

    NIR observations were made at the 3.8-m United Kingdom Infrared Telescope (UKIRT) with the facility imager UFTI. The UFTI pixel scale measures 0.091"; the available field of view is ~90". Photometric observations through JHK broad-band filters were secured for six fields during three nights of service observing (2000 September 15, 2001 May 31 and 2001 August 12). (4 data files).

  4. Multiaperture U BV RIzJHK Photometry of Galaxies in the Coma Cluster

    SciTech Connect

    Eisenhardt, P R; De Propris, R; Gonzalez, A H; Stanford, S A; Dickinson, M; Wang, M C

    2006-12-05

    We present a set of UBV RIzJHKs photometry for 745 J +H band selected objects in a 22:5{prime} x 29:2{prime} region centered on the core of the Coma cluster. This includes 516 galaxies and is at least 80% complete to H = 16, with a spectroscopically complete sample of 111 cluster members (nearly all with morphological classification) for H < 14:5. For each object we present total Kron (1980) magnitudes and aperture photometry. As an example, we use these data to derive color-magnitude relations for Coma early-type galaxies, measure the intrinsic scatter of these relations and its dependence on galaxy mass, and address the issue of color gradients. We find that the color gradients are mild and that the intrinsic scatter about the color-magnitude relation is small ({approx} 0:05 mag in U-V and less than {approx} 0:03 in B-R, V-I, or J-K). There is no evidence that the intrinsic scatter varies with galaxy luminosity, suggesting that the cluster red sequence is established at early epochs over a range of {approx} 100 in stellar mass.

  5. NEAR-INFRARED (JHK) PHOTOMETRY OF 131 NORTHERN GALACTIC CLASSICAL CEPHEIDS

    SciTech Connect

    Monson, Andrew J.; Pierce, Michael J.

    2011-03-15

    Near-infrared photometric measurements for 131 Northern Galactic Cepheids are presented. The Cepheid light curves are sampled with an average of 22 measurements per star fully covering the phase of each Cepheid. The J, H, and K light curves for each Cepheid were uniformly interpolated to find the intensity mean magnitudes within each band. The results are consistent within {+-}1% for 26 stars in common with previous studies. This paper is the first in a projected series of two papers which will provide additional fundamental data for Cepheids in the Galaxy, namely, NIR photometry and line-of-sight extinction. In the course of this project, 93 additional variables were fortuitously observed within the Cepheid program fields, 82 of which have previously not been identified.

  6. VizieR Online Data Catalog: JHK photometry of 1203 variables in ONC (Rice+, 2015)

    NASA Astrophysics Data System (ADS)

    Rice, T. S.; Reipurth, B.; Wolk, S. J.; Vaz, L. P.; Cross, N. J. G.

    2016-04-01

    Our data comprise J, H, K observations of a 0.9°*0.9° field toward the Orion Nebula Cluster (ONC) that were taken with the Wide Field Camera (WFCAM) instrument on the 3.8m UKIRT, which sits atop Mauna Kea, HI at 4194m elevation. Observations have been taken on 120 nights between 2006 October and 2009 April over three observing seasons: 2006 October 26-2007 April 21, 2007 November 21-2007 December 2, and 2008 November 8-2009 April 7. We monitored ~15000 stars down to J~20 using the WFCAM instrument, and have extracted 1203 significantly variable stars from our data. The observations came from UKIRT/WFCAM programmes U/06B/H54, U/07B/H60B, and U/09A/H33 and were combined into a single WFCAM Science Archive (WSA) combined programme WSERV5. The data in this paper come from the data release WSERV5v20120208, and can be accessed at http://surveys.roe.ac.uk/wsa. The coordinates, SIMBAD cross-matched names, median WFCAM photometry, Spitzer photometry, and evolutionary classes of all 1203 variables are listed in Table2. In Tables 4 and 5, we show the variability statistics, including derived color slopes, for all periodic and nonperiodic stars in our data set, respectively. We identify long-term periodic stars in Table6. In Table7 we list the four newly discovered eclipsing binaries and their basic data, together with nine other eclipsing binaries that fall within our WFCAM field. (5 data files).

  7. High-precision 2MASS JHK{sub s} light curves and other data for RR Lyrae star SDSS J015450 + 001501: Strong constraints for nonlinear pulsation models

    SciTech Connect

    Szabó, Róbert; Ivezić, Željko; Kiss, László L.; Kolláth, Zoltán; Jones, Lynne; Becker, Andrew C.; Davenport, James R. A.; Sesar, Branimir; Cutri, Roc M.

    2014-01-01

    We present and discuss an extensive data set for the non-Blazhko ab-type RR Lyrae star SDSS J015450+001501, including optical Sloan Digital Sky Survey ugriz light curves and spectroscopic data, LINEAR and Catalina Sky Survey unfiltered optical light curves, and infrared Two Micron All Sky Survey (2MASS) JHK{sub s} and Wide-field Infrared Survey Explorer W1 and W2 light curves. Most notable is that light curves obtained by 2MASS include close to 9000 photometric measures collected over 3.3 yr and provide an exceedingly precise view of near-infrared variability. These data demonstrate that static atmosphere models are insufficient to explain multiband photometric light-curve behavior and present strong constraints for nonlinear pulsation models for RR Lyrae stars. It is a challenge to modelers to produce theoretical light curves that can explain data presented here, which we make publicly available.

  8. New 2MASS near-infrared photometry for globular clusters in M31

    SciTech Connect

    Wang, Song; Ma, Jun; Wu, Zhenyu; Zhou, Xu

    2014-07-01

    We present Two Micron All Sky Survey JHK {sub s} photometry for 913 star clusters and candidates in the field of M31, which are selected from the latest Revised Bologna Catalog of M31 globular clusters (GCs) and candidates. The photometric measurements in this paper supplement this catalog, and provide the most comprehensive and homogeneous photometric catalog for M31 GCs in the JHK {sub s} bandpasses. In general, our photometry is consistent with previous measurements. The globular cluster luminosity function (GCLF) peaks for the confirmed GCs derived by fitting a t {sub 5} distribution using the maximum likelihood method are J{sub 0}=15.348{sub −0.208}{sup +0.206}, H{sub 0}=14.703{sub −0.180}{sup +0.176}, and K{sub s0}=14.534{sub −0.146}{sup +0.142}, all of which agree well with previous studies. The GCLFs are different between metal-rich (MR) and metal-poor (MP), and between inner and outer subpopulations, as MP clusters are fainter than their MR counterparts and the inner clusters are brighter than the outer ones, which confirm previous results. The NIR colors of the GC candidates are on average redder than those of the confirmed GCs, which leads to an obscure bimodal distribution of color indices. The relation of (V – K {sub s}){sub 0} and metallicity shows a notable departure from linearity, with a shallower slope toward the redder end. The color-magnitude diagram (CMD) and color-color diagram show that many GC candidates are located out of the evolutionary tracks, suggesting that some of them may be false M31 GC candidates. The CMD also shows that the initial mass function of M31 GCs covers a large range, and the majority of the clusters have initial masses between 10{sup 3} and 10{sup 6} M {sub ☉}.

  9. Near-infrared photometry and spectroscopy of the low Galactic latitude globular cluster 2MASS-GC 03

    NASA Astrophysics Data System (ADS)

    Carballo-Bello, Julio A.; Ramírez Alegría, S.; Borissova, J.; Smith, L. C.; Kurtev, R.; Lucas, P. W.; Moni Bidin, Ch.; Alonso-García, J.; Minniti, D.; Palma, T.; Dékány, I.; Medina, N.; Moyano, M.; Villanueva, V.; Kuhn, M. A.

    2016-10-01

    We present deep near-infrared photometry and spectroscopy of the globular cluster 2MASS-GC 03 projected in the Galactic disc using MMT and Magellan Infrared Spectrograph on the Clay Telescope (Las Campanas Observatory) and VISTA Variables in the Via Lactea Survey data. Most probable cluster member candidates were identified from near-infrared photometry. Out of 10 candidates that were followed-up spectroscopically, 5 have properties of cluster members, from which we calculate <[Fe/H]>= - 0.9 ± 0.2 and a radial velocity of = - 78 ± 12 km s-1. A distance of 10.8 kpc is estimated from three likely RR Lyrae members. Given that the cluster is currently at a distance of 4.2 kpc from the Galactic Centre, the cluster's long survival time of an estimated 11.3 ± 1.2 Gyr strengthens the case for its globular-cluster nature. The cluster has a hint of elongation in the direction of the Galactic Centre.

  10. 2MASS photometry and kinematical studies of open cluster NGC 188

    NASA Astrophysics Data System (ADS)

    Elsanhoury, W. H.; Haroon, A. A.; Chupina, N. V.; Vereshchagin, S. V.; Sariya, Devesh P.; Yadav, R. K. S.; Jiang, Ing-Guey

    2016-11-01

    In this paper, we present our results for the photometric and kinematical studies of old open cluster NGC 188. We determined various astrophysical parameters like limited radius, core and tidal radii, distance, luminosity and mass functions, total mass, relaxation time etc. for the cluster using 2MASS catalog. We obtained the cluster's distance from the Sun as 1721 ± 41 pc and log (age)= 9.85 ± 0.05 at Solar metallicity. The relaxation time of the cluster is smaller than the estimated cluster age which suggests that the cluster is dynamically relaxed. Our results agree with the values mentioned in the literature. We also determined the clusters apex coordinates as (281°.88, -44∘ .76) using AD-diagram method. Other kinematical parameters like space velocity components, cluster center and elements of Solar motion etc. have also been computed.

  11. Three-dimensional reddening map for stars from 2MASS photometry: The method and the first results

    NASA Astrophysics Data System (ADS)

    Gontcharov, G. A.

    2010-08-01

    The first results of the construction of a three-dimensional reddening map for stars within 1600 pc of the Sun are presented. Analysis of the distribution of 70 million stars from the 2MASS catalog with the most accurate photometry on the ( J-Ks)- Ks diagram supplemented with Monte Carlo simulations has shown that one of the maxima of this distribution corresponds to F-type dwarfs and subgiants with a mean absolute magnitude M Ks = 2{⊙/ m }5. The shift of this maximum toward large J-Ks with increasing Ks reflects the reddening of these stars with increasing heliocentric distance. The distribution of the sample of stars over Ks, l, and b cells with a statistically significant number of stars in each cell corresponds to their distribution over three-dimensional spatial cells. As a result, the reddening E( J-Ks) has been determined with an accuracy of 0{·/ m }03 for spatial cells with a side of 100 pc. All of the known large absorbing clouds within 1600 pc of the Sun have manifested themselves in the results obtained. The distances to the near and far edges of the clouds have been determined with a relative accuracy of 15%. The cases where unknown clouds are hidden behind known ones on the same line of sight have been found. The distance dependence of reddening is considered for various Galactic latitudes and longitudes. The absorbing matter of the Gould Belt is shown to manifest itself at latitudes up to 40° and within 600 pc of the Sun. The size and influence of the Gould Belt may have been underestimated thus far. The absorbing matter at latitudes up to 60° and within 1600 pc of the Sun has been found to be distributed predominantly in the first and second quadrants in the southern hemisphere and in the third and fourth quadrants in the northern hemisphere. The warping of the absorbing layer in the near Galaxy apparently manifests itself in this way. A nonrandom orientation of the clouds relative to the Sun is possible. The mass of the baryonic dark matter in

  12. Characterization of the Praesepe star cluster by photometry and proper motions with 2MASS, PPMXL, and Pan-STARRS

    SciTech Connect

    Wang, P. F.; Chen, W. P.; Lin, C. C.; Huang, C. K.; Panwar, N.; Lee, C. H.; Pandey, A. K.; Tsai, M. F.; Tang, C.-H.; Goldman, B.; Burgett, W. S.; Chambers, K. C.; Flewelling, H.; Heasley, J. N.; Hodapp, K. W.; Huber, M. E.; Jedicke, R.; Kaiser, N.; Draper, P. W.; Grav, T.; and others

    2014-03-20

    Membership identification is the first step in determining the properties of a star cluster. Low-mass members in particular could be used to trace the dynamical history, such as mass segregation, stellar evaporation, or tidal stripping, of a star cluster in its Galactic environment. We identified member candidates of the intermediate-age Praesepe cluster (M44) with stellar masses ∼0.11-2.4 M {sub ☉}, using Panoramic Survey Telescope And Rapid Response System and Two Micron All Sky Survey photometry, and PPMXL proper motions. Within a sky area of 3° radius, 1040 candidates are identified, of which 96 are new inclusions. Using the same set of selection criteria on field stars, an estimated false positive rate of 16% was determined, suggesting that 872 of the candidates are true members. This most complete and reliable membership list allows us to favor the BT-Settl model over other stellar models. The cluster shows a distinct binary track above the main sequence, with a binary frequency of 20%-40%, and a high occurrence rate of similar mass pairs. The mass function is consistent with that of the disk population but shows a deficit of members below 0.3 solar masses. A clear mass segregation is evidenced, with the lowest-mass members in our sample being evaporated from this disintegrating cluster.

  13. Characterization of the Praesepe Star Cluster by Photometry and Proper Motions with 2MASS, PPMXL, and Pan-STARRS

    NASA Astrophysics Data System (ADS)

    Wang, P. F.; Chen, W. P.; Lin, C. C.; Pandey, A. K.; Huang, C. K.; Panwar, N.; Lee, C. H.; Tsai, M. F.; Tang, C.-H.; Goldman, B.; Burgett, W. S.; Chambers, K. C.; Draper, P. W.; Flewelling, H.; Grav, T.; Heasley, J. N.; Hodapp, K. W.; Huber, M. E.; Jedicke, R.; Kaiser, N.; Kudritzki, R.-P.; Luppino, G. A.; Lupton, R. H.; Magnier, E. A.; Metcalfe, N.; Monet, D. G.; Morgan, J. S.; Onaka, P. M.; Price, P. A.; Stubbs, C. W.; Sweeney, W.; Tonry, J. L.; Wainscoat, R. J.; Waters, C.

    2014-03-01

    Membership identification is the first step in determining the properties of a star cluster. Low-mass members in particular could be used to trace the dynamical history, such as mass segregation, stellar evaporation, or tidal stripping, of a star cluster in its Galactic environment. We identified member candidates of the intermediate-age Praesepe cluster (M44) with stellar masses ~0.11-2.4 M ⊙, using Panoramic Survey Telescope And Rapid Response System and Two Micron All Sky Survey photometry, and PPMXL proper motions. Within a sky area of 3° radius, 1040 candidates are identified, of which 96 are new inclusions. Using the same set of selection criteria on field stars, an estimated false positive rate of 16% was determined, suggesting that 872 of the candidates are true members. This most complete and reliable membership list allows us to favor the BT-Settl model over other stellar models. The cluster shows a distinct binary track above the main sequence, with a binary frequency of 20%-40%, and a high occurrence rate of similar mass pairs. The mass function is consistent with that of the disk population but shows a deficit of members below 0.3 solar masses. A clear mass segregation is evidenced, with the lowest-mass members in our sample being evaporated from this disintegrating cluster.

  14. AN EMPIRICAL UBV RI JHK COLOR-TEMPERATURE CALIBRATION FOR STARS

    SciTech Connect

    Worthey, Guy; Lee, Hyun-chul

    2011-03-15

    A collection of Johnson/Cousins photometry for stars with known [Fe/H] is used to generate color-color relations that include the abundance dependence. Literature temperature and bolometric correction (BC) dependences are attached to the color relations. The JHK colors are transformed to the Bessell and Brett homogenized system. The main result of this work is the tabulation of seven colors and the V-band BC as a function of T {sub eff}, log g, and [Fe/H] for -1.06 < V - K < 10.2 and an accompanying interpolation program. Improvements to the present calibration would involve filling photometry gaps, obtaining more accurate and on-system photometry, knowing better log g and [Fe/H] values, improving the statistics for data-impoverished groups of stars such as metal-poor K dwarfs, applying small tweaks in the processing pipeline, and obtaining better empirical temperature and BC relations, especially for supergiants and M stars. A way to estimate dust extinction from M dwarf colors is pointed out.

  15. VizieR Online Data Catalog: VRIZJHK photometry around Alpha Cen (Kervella+, 2007)

    NASA Astrophysics Data System (ADS)

    Kervella, P.; Thevenin, F.

    2016-06-01

    table1.dat lists the background sources identified on deep CCD images of the close environment of Alpha Centauri (up to approximately 2.5'). Our VRIZ photometry has been complemented by JHK photometry extracted from the corresponding 2MASS images (Skrutskie et al., 2006AJ....131.1163S). This catalogue is particularly intended to provide a reference for future searches for faint companions of Alpha Centauri. Unavailable values are replaced by 99.00 in the table. We have revised the coordinates of the catalogue published in 2007. They are now much more consistent with reference astrometric catalogues such as 2MASS (Cat. II/246). There was a shift of typically 2 arcseconds between the 2MASS and SUSI2 coordinates, and now this is reduced to less than 0.5 arcsecond. We have also recomputed the photometric magnitudes using more accurate aperture corrections and instrument zero points The new version of the table is available on 13-Jun-2016, in place of the old one, in Vizier. (1 data file).

  16. VizieR Online Data Catalog: Blue stars with disk photometry in NGC 6611 (Guarcello+, 2010)

    NASA Astrophysics Data System (ADS)

    Guarcello, M. G.; Damiani, F.; Micela, G.; Peres, G.; Prisinzano, L.; Sciortino, S.

    2010-06-01

    This catalog contains coordinates and both optical and infrared photometry, plus usefull tags, of the Blue Stars With Disk (BWE stars) discussed in detail in Guarcello et al. (2010, in prep): "Pre-main sequence stars with disks in the Eagle nebula observed in scattered light". The optical photometry in BVI bands comes from observations with WFI@ESO (Guarcello et al. 2007, Cat. J/A+A/462/245); JHK photometry have been obtained from 2MASS/PSC and UKIDSS/GPS catalogs (Bonatto et al., 2006A&A...445..567B, Guarcello et al., 2007, Cat. J/A+A/462/245 and 2010, in prep); IRAC data are from GLIMPSE public survey (Indebetouw 2007ApJ...666..321I, Guarcello et al., 2009, Cat. J/A+A/496/453); X-ray data from observations with Chandra/ACIS-I (Linsky et al. 2007, Cat. J/ApJ/654/347, Guarcello et al., 2007, Cat. J/A+A/462/245, Guarcello et al., 2010, in prep). BWE stars have been studied by analizing their Spectral Energy Distribution (SED) using the grid of YSO models developed by Robitaille et al. 2006ApJS..167..256R. (1 data file).

  17. VizieR Online Data Catalog: JHK photometry near IRAS 06145+1455 (Brand+, 2007)

    NASA Astrophysics Data System (ADS)

    Brand, J.; Wouterloot, J. G. A.

    2007-09-01

    The data presented here were obtained on February 15, 1995, with the ESO 2.2-m telescope at La Silla (Chile). Images in J, H, and K-bands were taken with the IRAC-2 camera and objective C, which resulted in a scale of 0.49"/pixel. (1 data file).

  18. APASS Landolt-Sloan BVgri photometry of Rave stars. I. Data, effective temperatures, and reddenings

    SciTech Connect

    Munari, U.; Siviero, A.; Henden, A.; Frigo, A.; Bienaymé, O.; Siebert, A.; Bland-Hawthorn, J.; Boeche, C.; Grebel, E. K.; Freeman, K. C.; Gibson, B. K.; Gilmore, G.; Kordopatis, G.; Helmi, A.; Levine, S. E.; Navarro, J. F.; Parker, Q. A.; Reid, W.; Seabroke, G. M.; and others

    2014-11-01

    We provide AAVSO Photometric All-Sky Survey (APASS) photometry in the Landolt BV and Sloan g'r'i' bands for all 425,743 stars included in the fourth RAVE Data Release. The internal accuracy of the APASS photometry of RAVE stars, expressed as the error of the mean of data obtained and separately calibrated over a median of four distinct observing epochs and distributed between 2009 and 2013, is 0.013, 0.012, 0.012, 0.014, and 0.021 mag for the B, V, g', r', and i' bands, respectively. The equally high external accuracy of APASS photometry has been verified on secondary Landolt and Sloan photometric standard stars not involved in the APASS calibration process and on a large body of literature data on field and cluster stars, confirming the absence of offsets and trends. Compared with the Carlsberg Meridian Catalog (CMC-15), APASS astrometry of RAVE stars is accurate to a median value of 0.098 arcsec. Brightness distribution functions for the RAVE stars have been derived in all bands. APASS photometry of RAVE stars, augmented by 2MASS JHK infrared data, has been χ{sup 2} fitted to a densely populated synthetic photometric library designed to widely explore temperature, surface gravity, metallicity, and reddening. Resulting T {sub eff} and E {sub B–V}, computed over a range of options, are provided and discussed, and will be kept updated in response to future APASS and RAVE data releases. In the process, we find that the reddening caused by a homogeneous slab of dust, extending for 140 pc on either side of the Galactic plane and responsible for E{sub B−V}{sup poles} = 0.036 ± 0.002 at the Galactic poles, is a suitable approximation of the actual reddening encountered at Galactic latitudes |b| ≥ 25°.

  19. APASS Landolt-Sloan BVgri Photometry of RAVE Stars. I. Data, Effective Temperatures, and Reddenings

    NASA Astrophysics Data System (ADS)

    Munari, U.; Henden, A.; Frigo, A.; Zwitter, T.; Bienaymé, O.; Bland-Hawthorn, J.; Boeche, C.; Freeman, K. C.; Gibson, B. K.; Gilmore, G.; Grebel, E. K.; Helmi, A.; Kordopatis, G.; Levine, S. E.; Navarro, J. F.; Parker, Q. A.; Reid, W.; Seabroke, G. M.; Siebert, A.; Siviero, A.; Smith, T. C.; Steinmetz, M.; Templeton, M.; Terrell, D.; Welch, D. L.; Williams, M.; Wyse, R. F. G.

    2014-11-01

    We provide AAVSO Photometric All-Sky Survey (APASS) photometry in the Landolt BV and Sloan g'r'i' bands for all 425,743 stars included in the fourth RAVE Data Release. The internal accuracy of the APASS photometry of RAVE stars, expressed as the error of the mean of data obtained and separately calibrated over a median of four distinct observing epochs and distributed between 2009 and 2013, is 0.013, 0.012, 0.012, 0.014, and 0.021 mag for the B, V, g', r', and i' bands, respectively. The equally high external accuracy of APASS photometry has been verified on secondary Landolt and Sloan photometric standard stars not involved in the APASS calibration process and on a large body of literature data on field and cluster stars, confirming the absence of offsets and trends. Compared with the Carlsberg Meridian Catalog (CMC-15), APASS astrometry of RAVE stars is accurate to a median value of 0.098 arcsec. Brightness distribution functions for the RAVE stars have been derived in all bands. APASS photometry of RAVE stars, augmented by 2MASS JHK infrared data, has been χ2 fitted to a densely populated synthetic photometric library designed to widely explore temperature, surface gravity, metallicity, and reddening. Resulting T eff and E B - V , computed over a range of options, are provided and discussed, and will be kept updated in response to future APASS and RAVE data releases. In the process, we find that the reddening caused by a homogeneous slab of dust, extending for 140 pc on either side of the Galactic plane and responsible for EpolesB-V = 0.036 ± 0.002 at the Galactic poles, is a suitable approximation of the actual reddening encountered at Galactic latitudes |b| >= 25°.

  20. Astronomical photometry

    NASA Astrophysics Data System (ADS)

    Henden, Arne A.; Kaitchuck, Ronald H.

    A handbook of astronomical photometry is presented in a format amenable to both professional and amateur use. The fundamental equipment, procedures, theory, and applications of photometry are described. Photometric systems such as the UBV, M-K, and Stromgren classification methods are explained, together with statistical treatments of photometric data. Data reduction techniques and applications in air-mass calculations, the determination of first-order extinction, and for computing zero-point values are defined. Baseline standards such as solar, universal,and sidereal time, and dating methods are provided. Instructions for constructing photometer heads are given, and the operational principles and techniques for using pulse-counting and dc electronics are explored. Finally, observational techniques and applications of photoelectric photometry are suggested and targets are indicated. A review is also offered of the theoretical basis and computational tools involved in the science of astronomical photometry.

  1. Partial molecular cloning of the JHK retrovirus using gammaretrovirus consensus PCR primers

    PubMed Central

    Halligan, Brian D; Sun, Hai-Yuan; Kushnaryov, Vladimir M; Grossberg, Sidney E

    2013-01-01

    The JHK virus (JHKV) was previously described as a type C retrovirus that has some distinctive ultrastructural features and replicates constitutively in a human B-lymphoblastoid cell line, JHK-3. In order to facilitate the cloning of sequences from JHKV, a series of partially degenerate consensus retroviral PCR primers were created by a data-driven design approach based on an alignment of 14 diverse gammaretroviral genomes. These primers were used in the PCR amplification of purified JHK virion cDNA, and ana lysis of the resulting amplified sequence indicates that the JHKV is in the murine leukemia virus (MLV) family. The JHK sequence is nearly identical to the corresponding region of the Bxv-1 endogenous mouse retrovirus (GenBank accession AC115959) and distinct from XMRV. JHKV gag-specific amplification was demonstrated with nucleic acids from uncultivated, frozen, peripheral blood mononuclear cells (PBMCs) of the index patient, but not in PBMCs from nine healthy blood donors. Unlike earlier reports, in which MLV-like sequences were identified in human source material, which may have been due to murine contamination, budding retrovirions were demonstrated repeatedly by electron microscopy in uncultivated lymphocytes of the index patient that were morphologically identical in their development to the virions in the JHK-3 cells, and immunological evidence was obtained that the index patient produced IgG antibodies that bound to the budding viral particles in patient PBMCs and in the JHK-3 cells. These data indicate that the patient had been infected by JHKV, lending significance to the demonstration of JHKV amplicons in nucleic acids of the patient’s PBMCs. In future studies, the PCR primer sets described herein may expand the detection of an amplifiable subset of viruses related to MLV. PMID:24159361

  2. J, H, K photometry of 433 Eros and other asteroids

    NASA Technical Reports Server (NTRS)

    Chapman, C. R.; Morrison, D.

    1976-01-01

    Results are reported for IR photometry of nine bright asteroids, including 433 Eros, which was conducted in the J, H, K, and (for Eros) L bands with an InSb photometer on the 1.3-m Kitt Peak telescope. It is found that the J-H and H-K color indices of all nine asteroids are slightly redder than those of the sun and that three C-type objects are somewhat redder in the same color indices than four S-types and an E-type. Eros is shown to have an unusually red J-K index; the shape of its IR spectral reflectance curve is attributed in part to the presence of the weak 2-micron pyroxene absorption band in the spectrum. The results show that JHK photometry is less diagnostic of asteroidal composition than higher-resolution IR spectrophotometry.

  3. Photutils: Photometry tools

    NASA Astrophysics Data System (ADS)

    Bradley, Larry; Sipocz, Brigitta; Robitaille, Thomas; Tollerud, Erik; Deil, Christoph; Vinícius, Zè; Barbary, Kyle; Günther, Hans Moritz; Bostroem, Azalee; Droettboom, Michael; Bray, Erik; Bratholm, Lars Andersen; Pickering, T. E.; Craig, Matt; Pascual, Sergio; Greco, Johnny; Donath, Axel; Kerzendorf, Wolfgang; Littlefair, Stuart; Barentsen, Geert; D'Eugenio, Francesco; Weaver, Benjamin Alan

    2016-09-01

    Photutils provides tools for detecting and performing photometry of astronomical sources. It can estimate the background and background rms in astronomical images, detect sources in astronomical images, estimate morphological parameters of those sources (e.g., centroid and shape parameters), and perform aperture and PSF photometry. Written in Python, it is an affiliated package of Astropy (ascl:1304.002).

  4. L' AND M' Photometry Of Ultracool Dwarfs

    NASA Technical Reports Server (NTRS)

    Marley, M. S.; Tsvetanov, Z. I.; Vrba, F. J.; Henden, A. A.; Luginbuhl, C. B.

    2004-01-01

    We have compiled L' (3.4-4.1 microns) and M' (4.6- 4.8 microns) photometry of 63 single and binary M, L, and T dwarfs obtained at the United Kingdom Infrared Telescope using the Mauna Kea Observatory filter set. This compilation includes new L' measurements of eight L dwarfs and 13 T dwarfs and new M' measurements of seven L dwarfs, five T dwarfs, and the M1 dwarf Gl 229A. These new data increase by factors of 0. 6 and 1.6, respectively, the numbers of ultracool dwarfs T (sub eff) JHK spectra, L' photometry, and trigonometric parallaxes are available, and we estimate these quantities for nine other dwarfs whose parallaxes and flux-calibrated spectra have been obtained. BC(SUB K) is a well-behaved function of near-infrared spectral type with a dispersion of approx. 0.1 mag for types M6-T5 it is significantly more scattered for types T5-T9. T (sub eff) declines steeply and monotonically for types M6-L7 and T4-T9, but it is nearly constant at approx. 1450 K for types L7-T4 with assumed ages of approx. 3 Gyr. This constant T(sub eff) is evidenced by nearly unchanging values of L'-M' between types L6 and T3. It also supports recent models that attribute the changing near-infrared luminosities and spectral features across the L-T transition to the rapid migration, disruption, and/or thinning of condensate clouds over a narrow range of T(sub eff). The L' and M' luminosities of early-T dwarfs do not exhibit the pronounced humps or inflections previously noted in l through K bands, but insufficient data exist for types L6-T5 to assert that M(Sub L') and M(sub M') are strictly monotonic within this range of typew. We compare the observed K, L', and M' luminosities of L and T dwarfs in our sample with those predicted by precipitation-cloud-free models for varying surface gravities and sedimentation efficiencies.

  5. APT: Aperture Photometry Tool

    NASA Astrophysics Data System (ADS)

    Laher, Russ

    2012-08-01

    Aperture Photometry Tool (APT) is software for astronomers and students interested in manually exploring the photometric qualities of astronomical images. It has a graphical user interface (GUI) which allows the image data associated with aperture photometry calculations for point and extended sources to be visualized and, therefore, more effectively analyzed. Mouse-clicking on a source in the displayed image draws a circular or elliptical aperture and sky annulus around the source and computes the source intensity and its uncertainty, along with several commonly used measures of the local sky background and its variability. The results are displayed and can be optionally saved to an aperture-photometry-table file and plotted on graphs in various ways using functions available in the software. APT is geared toward processing sources in a small number of images and is not suitable for bulk processing a large number of images, unlike other aperture photometry packages (e.g., SExtractor). However, APT does have a convenient source-list tool that enables calculations for a large number of detections in a given image. The source-list tool can be run either in automatic mode to generate an aperture photometry table quickly or in manual mode to permit inspection and adjustment of the calculation for each individual detection. APT displays a variety of useful graphs, including image histogram, and aperture slices, source scatter plot, sky scatter plot, sky histogram, radial profile, curve of growth, and aperture-photometry-table scatter plots and histograms. APT has functions for customizing calculations, including outlier rejection, pixel “picking” and “zapping,” and a selection of source and sky models. The radial-profile-interpolation source model, accessed via the radial-profile-plot panel, allows recovery of source intensity from pixels with missing data and can be especially beneficial in crowded fields.

  6. STAR CLUSTERS IN M33: UPDATED UBVRI PHOTOMETRY, AGES, METALLICITIES, AND MASSES

    SciTech Connect

    Fan, Zhou; De Grijs, Richard E-mail: grijs@pku.edu.cn

    2014-04-01

    The photometric characterization of M33 star clusters is far from complete. In this paper, we present homogeneous UBVRI photometry of 708 star clusters and cluster candidates in M33 based on archival images from the Local Group Galaxies Survey, which covers 0.8 deg{sup 2} along the galaxy's major axis. Our photometry includes 387, 563, 616, 580, and 478 objects in the UBVRI bands, respectively, of which 276, 405, 430, 457, and 363 do not have previously published UBVRI photometry. Our photometry is consistent with previous measurements (where available) in all filters. We adopted Sloan Digital Sky Survey ugriz photometry for complementary purposes, as well as Two Micron All Sky Survey near-infrared JHK photometry where available. We fitted the spectral-energy distributions of 671 star clusters and candidates to derive their ages, metallicities, and masses based on the updated PARSEC simple stellar populations synthesis models. The results of our χ{sup 2} minimization routines show that only 205 of the 671 clusters (31%) are older than 2 Gyr, which represents a much smaller fraction of the cluster population than that in M31 (56%), suggesting that M33 is dominated by young star clusters (<1 Gyr). We investigate the mass distributions of the star clusters—both open and globular clusters—in M33, M31, the Milky Way, and the Large Magellanic Cloud. Their mean values are log (M {sub cl}/M {sub ☉}) = 4.25, 5.43, 2.72, and 4.18, respectively. The fraction of open to globular clusters is highest in the Milky Way and lowest in M31. Our comparisons of the cluster ages, masses, and metallicities show that our results are basically in agreement with previous studies (where objects in common are available); differences can be traced back to differences in the models adopted, the fitting methods used, and stochastic sampling effects.

  7. Aperture Photometry Tool

    NASA Astrophysics Data System (ADS)

    Laher, Russ R.; Gorjian, Varoujan; Rebull, Luisa M.; Masci, Frank J.; Fowler, John W.; Helou, George; Kulkarni, Shrinivas R.; Law, Nicholas M.

    2012-07-01

    Aperture Photometry Tool (APT) is software for astronomers and students interested in manually exploring the photometric qualities of astronomical images. It is a graphical user interface (GUI) designed to allow the image data associated with aperture photometry calculations for point and extended sources to be visualized and, therefore, more effectively analyzed. The finely tuned layout of the GUI, along with judicious use of color-coding and alerting, is intended to give maximal user utility and convenience. Simply mouse-clicking on a source in the displayed image will instantly draw a circular or elliptical aperture and sky annulus around the source and will compute the source intensity and its uncertainty, along with several commonly used measures of the local sky background and its variability. The results are displayed and can be optionally saved to an aperture-photometry-table file and plotted on graphs in various ways using functions available in the software. APT is geared toward processing sources in a small number of images and is not suitable for bulk processing a large number of images, unlike other aperture photometry packages (e.g., SExtractor). However, APT does have a convenient source-list tool that enables calculations for a large number of detections in a given image. The source-list tool can be run either in automatic mode to generate an aperture photometry table quickly or in manual mode to permit inspection and adjustment of the calculation for each individual detection. APT displays a variety of useful graphs with just the push of a button, including image histogram, x and y aperture slices, source scatter plot, sky scatter plot, sky histogram, radial profile, curve of growth, and aperture-photometry-table scatter plots and histograms. APT has many functions for customizing the calculations, including outlier rejection, pixel "picking" and "zapping," and a selection of source and sky models. The radial-profile-interpolation source model

  8. VizieR Online Data Catalog: Very low mass objects in ONC (Rodriguez-Ledesma+, 2010)

    NASA Astrophysics Data System (ADS)

    Rodriguez-Ledesma, M. V.; Mundt, R.; Eisloeffel, J.

    2010-01-01

    Table 1 lists the 638 very low mass objects in the Orion Nebula Cluster with magnitudes between 14-21mag in I band for which NIR (JHK) photometry is available. The I band data is from Rodriguez-Ledesma et al. (2009, Cat. ) and JHK data from 2MASS, UKIDSS, and VLT. (1 data file).

  9. DOLPHOT: Stellar photometry

    NASA Astrophysics Data System (ADS)

    Dolphin, Andrew

    2016-08-01

    DOLPHOT is a stellar photometry package that was adapted from HSTphot for general use. It supports two modes; the first is a generic PSF-fitting package, which uses analytic PSF models and can be used for any camera. The second mode uses ACS PSFs and calibrations, and is effectively an ACS adaptation of HSTphot. A number of utility programs are also included with the DOLPHOT distribution, including basic image reduction routines.

  10. Third Workshop on Photometry

    NASA Technical Reports Server (NTRS)

    Borucki, William J. (Editor); Lasher, Lawrence E. (Editor)

    2001-01-01

    The discoveries of extrasolar planets by Wolszczan, Mayor and Queloz, Butler et al., and others have stimulated a widespread effort to obtain a body of data sufficient to understand their occurrence and characteristics. Doppler velocity techniques have found dozens of extrasolar planets with masses similar to that of Jupiter. Approximately ten percent of the stars that show planets with orbital periods of a few days to a week are expected to show transits. With the mass obtained from Doppler velocity measurements and the size from transit photometry, the densities of the planets can be determined. Theoretical models of the structure of "hot Jupiters" (i.e., those planets within a tenth of an astronomical unit (AU) of the parent star) indicate that these planets should be substantially larger in size and lower in density than Jupiter. Thus the combination of transit and Doppler velocity measurements provide a critical test of the theories of planetary structure. Furthermore, because photometry can be done with small-aperture telescopes rather than requiring the use of much larger telescopes, transit photometry should also reduce the cost of discovering extrasolar planets.

  11. VizieR Online Data Catalog: Physical parameters from JHK flux (Gonzalez-Hernandez+, 2009)

    NASA Astrophysics Data System (ADS)

    Gonzalez Hernandez, J. I.; Bonifacio, P.

    2009-01-01

    We have made use of the infrared flux method (IRFM) to determine effective temperatures of 555 dwarf and subgiant field stars, and 264 giant field stars. Our implementation of the IRFM uses the 2MASS photometric system as a reference system to perform all the calculations. Bolometric fluxes are derived using UBV(RI)cJHKs accurate photometric data. In tables dwarf.dat and giants.dat, we provide the photometric data and reddenings used in this paper, stellar parameters and metallicity, bolometric fluxes and IRFM temperatures and angular diameters for all the stars in our samples. In tables a*.dat, we provide A factors and Bx-B coefficients, necessary for the determination of bolometric fluxes, computed from the ATLAS theoretical fluxes of Castelli & Kurucz (2003, arXiv:astro-ph/0405087v1) We used the fluxes in the ranges 3500K2MASS system for each atmospheric model. The theoretical magnitudes are normalized to Vega (J=H=Ks=0 in the 2MASS photometric system). The model Flux for Vega is that computed by F. Castelli (http://wwwuser.oats.inaf.it/castelli/vega/fm05t9550g

  12. Draft Genome Sequence of Tepidiphilus thermophilus Strain JHK30T (JCM 19170T) Isolated from a Terrestrial Hot Spring in India

    PubMed Central

    Poddar, Abhijit; Lepcha, Rinchen T.; Whitman, William B.

    2016-01-01

    Tepidiphilus thermophilus strain JHK30T was isolated from a hot spring at Surajkund, Jharkhand, India. It is a Gram-negative rod, nonsporulating, aerobic, and motile. The estimated genome is 2.3 Mb, with 2,186 protein-coding sequences. PMID:27516519

  13. Draft Genome Sequence of Tepidiphilus thermophilus Strain JHK30T (JCM 19170T) Isolated from a Terrestrial Hot Spring in India.

    PubMed

    Poddar, Abhijit; Lepcha, Rinchen T; Whitman, William B; Das, Subrata K

    2016-01-01

    Tepidiphilus thermophilus strain JHK30(T) was isolated from a hot spring at Surajkund, Jharkhand, India. It is a Gram-negative rod, nonsporulating, aerobic, and motile. The estimated genome is 2.3 Mb, with 2,186 protein-coding sequences. PMID:27516519

  14. DEEP JHK{sub s} AND SPITZER IMAGING OF FOUR ISOLATED MOLECULAR CLOUD CORES

    SciTech Connect

    Chapman, Nicholas L.; Mundy, Lee G.

    2009-07-10

    We present observations in eight wavebands from 1.25 to 24 {mu}m of four dense cores: L204C-2, L1152, L1155C-2, and L1228. Our goals are to study the young stellar object (YSO) population of these cores and to measure the mid-infrared extinction law. With our combined near-infrared and Spitzer photometry, we classify each source in the cores as, among other things, background stars, galaxies, or embedded YSOs. L1152 contains three YSOs and L1228 has seven, but neither L204C-2 nor L1155C-2 appear to contain any YSOs. We estimate an upper limit of 7 x 10{sup -5} to 5 x 10{sup -4} L{sub sun} for any undiscovered YSOs in our cores. We also compute the line-of-sight extinction law toward each background star. These measurements are averaged spatially, to create {chi}{sup 2} maps of the changes in the mid-infrared extinction law throughout our cores, and also in different ranges of extinction. From the {chi}{sup 2} maps, we identify two small regions in L1152 and L1228 where the outflows in those cores appear to be destroying the larger dust grains, thus altering the extinction law in those regions. On average, however, our extinction law is relatively flat from 3.6 to 24 {mu}m for all ranges of extinction and in all four cores. From 3.6 to 8 {mu}m, this law is consistent with a dust model that includes larger dust grains than the diffuse interstellar medium, which suggests grain growth has occurred in our cores. At 24 {mu}m, our extinction law is two to four times higher than predicted by dust models. However, it is similar to other empirical measurements.

  15. Photometry and polarimetry study of cataclysmic variables (cvs)

    NASA Astrophysics Data System (ADS)

    Joshi, Arti

    2016-07-01

    We present time-resolved photometry and linear polarimetry of the two cataclysmic variables (CVs) 2MASS J01303186+6221324 and 2MASS J03451159+533514. We classify the system 2MASS J01303186+6221324 as a deeply eclipsing intermediate polar which exhibits a deep eclipse of 1.8 mag with orbital period of 3.58 hr. However, the orbital period of the system 2MASS J03451159+533514 is found to be 7.8 hr. We also report the polarimetric observations of these two systems, where the polarization data reveals same periods with those obtained from photometrically. The variations of linear polarization from 1.0-6.0 per cent are seen over an orbital cycle, with a minimum around the time of eclipse for both system.

  16. Sparse field stellar photometry.

    NASA Astrophysics Data System (ADS)

    Reid, N.

    The past few years have seen substantial developments in the capability of high speed measuring machines in the field of automated stellar photometry. In this review, after describing some of the limitations on photometric precision, empirical results are used to demonstrate the sort of accuracies that are possible with the UK Schmidt plate plus COSMOS/APM images-scan combination. The astronomical results obtained to date from these machines are discussed, and some consideration is given to the future role of measuring machines in stellar astronomy.

  17. Selecting M-giants with WISE photometry

    NASA Astrophysics Data System (ADS)

    Li, Jing

    2015-08-01

    We use M-giants, M-dwarfs and QSOs identified by LAMOST to assess how well WISE & 2MASS colour-cuts can separate these populations through photometry. We find that the WISE bands are very efficient to separate M-giants from M-dwarfs, especially for the early-type stars. We derive a new photometric relation to estimate [Fe/H] for M-giants. We show that previous photometric distance relations may be biased and devise a new empirical distance relation. We detect M-giants in the Sagittarius stream from the ALLWISE Source Archive. Our detection shows good agreement with the bright stream, although the leading tail appears to be misaligned by a couple of degrees. We have measured the metallicity distribution at four locations along the stream, finding a clear metallicity offset between the leading and trailing tails.

  18. Sparse field stellar photometry

    NASA Astrophysics Data System (ADS)

    Reid, N.

    The past few years have seen substantial developments in the capability of high speed measuring machines in the field of automated stellar photometry. However, it is only very recently that these machines have started to make any impact on stellar astronomy, and even now their potential is scarcely being exploited. In this review, after describing some of the limitations on photometric precision, empirical results are used to demonstrate the sort of accuracies that are possible with the UK Schmidt plate plus COSMOS/APM images-scan combination. The astronomical results obtained to date from these machines are discussed, and some consideration is given to the future role of measuring machines in stellar astronomy.

  19. k2photometry: Read, reduce and detrend K2 photometry

    NASA Astrophysics Data System (ADS)

    Van Eylen, Vincent; Nowak, Grzegorz; Albrecht, Simon; Palle, Enric; Ribas, Ignasi; Bruntt, Hans; Perger, Manuel; Gandolfi, Davide; Hirano, Teriyuki; Sanchis-Ojeda, Roberto; Kiilerich, Amanda; Arranz, Jorge P.; Badenas, Mariona; Dai, Fei; Deeg, Hans J.; Guenther, Eike W.; Montanes-Rodriguez, Pilar; Narita, Norio; Rogers, Leslie A.; Bejar, Victor J. S.; Shrotriya, Tushar S.; Winn, Joshua N.; Sebastian, Daniel

    2016-02-01

    k2photometry reads, reduces and detrends K2 photometry and searches for transiting planets. MAST database pixel files are used as input; the output includes raw lightcurves, detrended lightcurves and a transit search can be performed as well. Stellar variability is not typically well-preserved but parameters can be tweaked to change that. The BLS algorithm used to detect periodic events is a Python implementation by Ruth Angus and Dan Foreman-Mackey (https://github.com/dfm/python-bls).

  20. Exposing Sgr tidal debris behind the Galactic disc with M giants selected in WISE∩2MASS

    NASA Astrophysics Data System (ADS)

    Koposov, S. E.; Belokurov, V.; Zucker, D. B.; Lewis, G. F.; Ibata, R. A.; Olszewski, E. W.; López-Sánchez, Á. R.; Hyde, E. A.

    2015-01-01

    We show that a combination of infrared photometry from WISE and 2MASS surveys can yield highly pure samples of M giant stars. We take advantage of the new WISE∩2MASS M giant selection to trace the Sagittarius (Sgr) trailing tail behind the Galactic disc in the direction of the anticentre. The M giant candidates selected via broad-band photometry are confirmed spectroscopically using AAOmega on the Anglo-Australian Telescope in three fields around the extremity of the Sgr trailing tail in the Southern Galactic hemisphere. We demonstrate that at the Sgr longitude tilde{Λ }_{{⊙}} = 204°, the line-of-sight velocities of the trailing tail starts to deviate from the track of the Law & Majewski model, confirming the prediction of Belokurov et al. This discovery serves to substantiate the measurement of low differential orbital precession of the Sgr stream which in turn may imply diminished dark matter content within 100 kpc.

  1. CCD Photometry of Variables Stars

    NASA Astrophysics Data System (ADS)

    Jeffery, E. J.; Reed, M. D.

    2001-12-01

    With recent advances in Charged Coupled Devices (CCDs), it is now possible to do high speed CCD photometry. Though photelectric photometry has a rich history and many years of software development, CCDs have several advantages over photometers: They have a higher quantum efficiency and eliminate many of the problems associated with the requirement of a fixed aperture in photoelectric photometry. However, CCD photometry has yet to develop the necessary tools to efficiently reduce and analyze the quantities of time-series data produced. Two other areas where advancement is needed are in decreasing the CCD readout times and producing real time light curves. We present steps taken to address these two issues. Dead times were shortened by examining various CCD geometries and scripts were written to process the data more efficiently. Our work has produced efficient methods for obtaining and reducing high speed CCD observations and brings us a step closer to producing real time light curves.

  2. Heterochromatic flicker photometry.

    PubMed

    Bone, Richard A; Landrum, John T

    2004-10-15

    Measurement of the macular pigment optical density (MPOD) by heterochromatic flicker photometry (HFP) is accomplished by viewing a small circular stimulus that alternates between a test wavelength that is absorbed by the MP (typically--blue, 460 nm) and a reference wavelength that is not absorbed (typically-green, 540 nm). Flicker observed by the subject is reduced to a null point by adjusting the intensity of the former while viewing the stimulus centrally, and then peripherally. A higher intensity, I, of the blue component of the stimulus is needed under central viewing conditions owing to attenuation by the MP. The MPOD at the test wavelength is given by log (Icentral/Iperipheral). Variation of the test wavelength has been used to measure the MPOD spectrum. This in vitro MPOD spectrum matches that of the carotenoids present in the macular region of the retina and demonstrates the validity and specificity of this methodology. The distribution of MPOD in the retina can be determined with HFP using a series of annular stimuli of different diameters.

  3. Photometry from space

    NASA Technical Reports Server (NTRS)

    Nelson, M. J.; Bless, R. C.; Percival, J. W.; White, R. L.

    1992-01-01

    A brief description of the High Speed Photometer (HSP) of the Hubble Space Telescope is given, in particular the HSP light path, detectors, entrance apertures, and filters. The status of HSP testing to date is reported, and problems encountered with the bright earth and the telescope pointing system are described. The calibration effort for the HSP is well under way. Results of internal (instrument coordinate) aperture locations good to 0.05 arcsec and external (telescope coordinate) locations good to 0.02 arcsec are shown. The effects of spacecraft pointing and jitter on HSP photometry are detailed, and a preliminary measurement of spacecraft jitter with HSP is shown. The aperture calibration effort is verified by accurate pointing of a star to different HSP 1.0 arcsec entrance apertures, and photometric performance of the instrument is shown to be accurate to the 2 percent photon noise of the observations. Future science verification and guaranteed observing time programs are listed. Suggestions are made for future space-based photometers.

  4. THE 100 Myr STAR FORMATION HISTORY OF NGC 5471 FROM CLUSTER AND RESOLVED STELLAR PHOTOMETRY

    SciTech Connect

    Garcia-Benito, Ruben; Perez, Enrique; Maiz Apellaniz, Jesus; Cervino, Miguel; Diaz, Angeles I. E-mail: angeles.diaz@uam.es E-mail: jmaiz@iaa

    2011-04-15

    We show that star formation in the giant H II region NGC 5471 has been ongoing during the past 100 Myr. Using Hubble Space Telescope/Wide-Field Planetary Camera 2 F547M and F675W, ground-based JHK{sub s} , and GALEX FUV and NUV images, we have conducted a photometric study of the star formation history (SFH) in the massive giant extragalactic H II region NGC 5471 in M101. We perform a photometric study of the color-magnitude diagram (CMD) of the resolved stars and an integrated analysis of the main individual star-forming clusters and of NGC 5471 as a whole. The integrated UV-optical-NIR photometry for the whole region provides two different reference ages, 8 Myr and 60 Myr, revealing a complex SFH, clearly confirmed by the CMD-resolved stellar photometry analysis. The spatial distribution of the stars shows that the star formation in NGC 5471 has proceeded along the whole region during, at least, the last 100 Myr. The current ionizing clusters are enclosed within a large bubble, which is likely to have been produced by the stars that formed in a major event {approx}20 Myr ago.

  5. VizieR Online Data Catalog: Photometry of VdBH 222 stars and field stars (Marco+, 2014)

    NASA Astrophysics Data System (ADS)

    Marco, A.; Negueruela, I.; Gonzalez-Fernandez, C.; Maiz Apellaniz, J.; Dorda, R.; Clark, J. S.

    2014-05-01

    We obtained UBVR photometry of VdBH 222 using the ESO Faint Object Spectrograph and Camera (EFOSC2) on the NTT on the night of 24 June 2012. The instrument was equipped with CCD#40, which is a Loral/Lesser, thinned, AR-coated, UV-flooded, and MPP chip that is controlled by ESO-FIERA. It covers a field of view of and 4.1'x4.1' and has a pixel scale of 0.12". The JHK images were obtained using the Son OF Isaac (SOFI) near-IR spectrograph and camera on the NTT on 13 July 2008, equipped with a CCD providing a pixel scale of 0.288arcsec and an field of view of 4.92x4.95' (4 data files).

  6. VizieR Online Data Catalog: BVRI photometry of nova V445 Pup (Goranskij+, 2010)

    NASA Astrophysics Data System (ADS)

    Goranskij, V. P.; Shugarov, S. Yu.; Zharova, A. V.; Kroll, P.; Barsukova, E. A.

    2012-05-01

    In the Moscow SAI plate collection, we found 51 plates with images of V445 Pup taken with the SAI Crimean Station 40-cm f/4 astrograph and dated between 15 November 1969 and 4 November 1989. We found 56 measurable images of V445 Pup on the plates of the Sonneberg Observatory collection dated between 19 March 1984 and 17 January 1991. Additionally, we measured all the Internet-accessible Digital Sky Survey images of V445 Pup in B,R, and I bands and used 2MASS JHK magnitudes to study the spectral energy distribution of the progenitor. We performed our observations of the V445 Pup remnant between 31 March 2003 and 20 October 2009. These observations were acquired in the Special Astrophysical Observatory (SAO), with the 1-m Zeiss reflector and CCD UBVRcIc photometer equipped with an EEV 42-40 CCD chip. (4 data files).

  7. Interpreting Flux from Broadband Photometry

    NASA Astrophysics Data System (ADS)

    Brown, Peter J.; Breeveld, Alice; Roming, Peter W. A.; Siegel, Michael

    2016-10-01

    We discuss the transformation of observed photometry into flux for the creation of spectral energy distributions (SED) and the computation of bolometric luminosities. We do this in the context of supernova studies, particularly as observed with the Swift spacecraft, but the concepts and techniques should be applicable to many other types of sources and wavelength regimes. Traditional methods of converting observed magnitudes to flux densities are not very accurate when applied to UV photometry. Common methods for extinction and the integration of pseudo-bolometric fluxes can also lead to inaccurate results. The sources of inaccuracy, though, also apply to other wavelengths. Because of the complicated nature of translating broadband photometry into monochromatic flux densities, comparison between observed photometry and a spectroscopic model is best done by forward modeling the spectrum into the count rates or magnitudes of the observations. We recommend that integrated flux measurements be made using a spectrum or SED which is consistent with the multi-band photometry rather than converting individual photometric measurements to flux densities, linearly interpolating between the points, and integrating. We also highlight some specific areas where the UV flux can be mischaracterized.

  8. Detection by Transit Photometry

    NASA Technical Reports Server (NTRS)

    Borucki, William J.; Koch, David G.; Jenkins, Jon M.; DeVincenzi, D. (Technical Monitor)

    2002-01-01

    A periodic sequence of planetary transits provides a valid detection of an orbiting planet and provides the relative size of the planet and its orbital period. Ancillary measurements of the stellar spectrum and the variations of the star's radial velocity or position combined with stellar models allow the absolute size of the planet and its mass to be obtained. The results of this approach have already shown that the planet orbiting HD209458 has only 70% of the mass of Jupiter, but is nearly 50% larger in radius. Based on models of planetary structure, these results imply that the planet must have spent most of its lifetime so close to the star that it has not been able to cool and contract as have the giant planets in our Solar System. Thus its density is much less than Jupiter and Saturn and is actually less than that of water; i.e., about 0.4 gr/cu cm. If more sensitive measurements of the light curve of stars with closely orbiting planets can be made that provide the varying amplitude of the light reflected by the planet at various phases in its orbit, then characteristics of the planetary atmosphere can be obtained. Potentially, these data can identify major molecular species present in the atmosphere and tell us if clouds are present and yield the phase function of the aerosols. Although such detail cannot be obtained for Earth-size planets because their signal amplitudes are too small, it is possible to get data critical to the determination of the structure of extrasolar planetary systems. In particular, the size distributions and their orbital distributions can be measured by the transit photometry missions now in development. The COROT mission should be able to find large terrestrial planets in short-period orbits while the more ambitious Kepler and Eddington missions should be able to detect planets even smaller than the Earth and at orbital distances that place them in the habitable zone of their stars.

  9. VizieR Online Data Catalog: Photometry of nova LMC 2012 (Schwarz+, 2015)

    NASA Astrophysics Data System (ADS)

    Schwarz, G. J.; Shore, S. N.; Page, K. L.; Osborne, J. P.; Beardmore, A. P.; Walter, F. M.; Bode, M. F.; Drake, J. J.; Ness, J.-U.; Starrfield, S.; van Rossum, D. R.; Woodward, C. E.

    2015-03-01

    Nova LMC 2012 was discovered on March 26.397 UT (MJD56012.897) at a visual magnitude of 10.7 (Seach et al., 2012CBET.3071....1S). After discovery, LMC 2012 was observed by a number of different facilities at a variety of wavelengths. The discovery date is taken as day zero and the shorthand "Dn," where "n" is the number of days after day zero, is used here. Swift is a revolutionary facility for studying novae (see Schwarz et al. 2011, cat. J/ApJS/197/31, for details). Its three instruments cover the γ-ray (BAT), X-ray (XRT), plus UV and optical (UVOT) bandpasses. Swift obtained 74 uvm2 band (λeff=2246Å, FWHM=498Å) observations of LMC 2012 with the UVOT instrument from D1.2 until D671. There were also 12 uvw2 band (λeff=1928Å, FWHM=657Å) and nine uvw1 band (λeff=2600Å, FWHM=693Å) observations which were only obtained early on D1.2 and later during the observations after D300. The UVOT photometry is provided in Table2. LMC 2012 was extensively observed photometrically between D0.6 and D635 with the Small & Moderate Aperture Research Telescope System (SMARTS) at Cerro Tololo (see Walter et al., 2012PASP..124.1057W, for details). We obtained 250 photometric observations in BVRI/JHK from SMARTS. The optical photometry is supplemented with 54 early time CCD BVRI observations from the American Association of Variable Star Observers (AAVSO). The optical and near-infrared photometry is also given in Table2. (2 data files).

  10. Second Workshop on Improvements to Photometry

    NASA Technical Reports Server (NTRS)

    Borucki, William J. (Editor)

    1988-01-01

    The papers in these proceedings show that a major effort is under way to improve all aspects of photometry. Astronomical multichannel photometry, photodiodes, analog-to-digital converters, data reduction techniques, interference filters and optical fibers are discussed.

  11. A 3D dust map from Pan-STARRS 1 photometry

    NASA Astrophysics Data System (ADS)

    Green, Gregory M.

    We have constructed a three-dimensional map of dust in the Milky Way, tracing reddening on ˜ 7' scales out to a distance of several kiloparsecs. We trace reddening using stars embedded in the dust, by simultaneously inferring stellar distance, stellar type, and the reddening along the line of sight. We use 5-band grizy Pan-STARRS 1 photometry of 800 million stars, augmented by 3-band 2MASS JHKs photometry when available. The full map is available at http://argonaut.skymaps.info. An online version of this talk is available at http://http://greg.ory.gr/present/ewass2015.

  12. Potential Nearby M Dwarf Stars Selected from the 2MASS Catalogs

    NASA Astrophysics Data System (ADS)

    Robertson, Thomas H.; Thompson, Dayna L.

    2016-01-01

    Potential nearby red dwarf stars have been selected from the 2MASS catalogs using assumptions about apparent magnitudes and colors. Candidate stars in this study are north of the celestial equator and have been restricted to galactic latitudes greater than 20 degrees from the galactic plane to permit subsequent aperture photometry with small telescopes. Stars with close companions have also been eliminated. Most probable M giant stars were eliminated using the (J-H) - (H-K) two-color diagram. Proper motions were obtained from the USNO-B catalog. Additional potential M giant stars were eliminated by removing stars with very low proper motions. Known nearby stars were removed from the list and stars with proper motions greater than 0.175 arcsec yr-1 were also removed, since such stars will likely be studied in other programs devoted to stars of known proper motion. Photometric parallaxes for the candidate stars were computed using 2MASS photometry and stars having average photometric distances of 25 pc or less were retained. A sample of 121 stars was produced. These stars are being observed using Kron-Cousins R, I and CaH photometry. To date about 75% of the program stars have been observed. All are confirmed dwarf stars and about 50% have distances of 25 pc or less based on photometric parallaxes using Kron-Cousins photometry.This publication makes use of data products from the Two Micron All Sky Survey and the U.S. Naval Observatory B1.0 Catalog. Services and products provided by the Strasbourg Astronomical Data Center (CDS) and US Virtual Astronomical Observatory (VAO) were used in processing the data. Observations have been obtained using the telescopes of the Southeastern Association for Research in Astronomy (SARA).

  13. Far-Ultraviolet Stellar Photometry

    NASA Astrophysics Data System (ADS)

    Schmidt, E. G.; Carruthers, G. R.

    1993-12-01

    During a shuttle flight in May, 1991, wide field images were obtained for 12 star fields with the NRL far-ultraviolet cameras. These cameras provide sensitivity bands with effective wavelengths of lambda eff = 1367 Angstroms and lambda eff = 1702 Angstroms. The properties of the resulting magnitude system will be described and compared with previous photometry from the OAO2, ANS and TD1 satellites. Results from several fields in the vicinity of the galactic center will be discussed.

  14. VizieR Online Data Catalog: Photometry of VVV CL041 cluster (Chene+, 2015)

    NASA Astrophysics Data System (ADS)

    Chene, A.-N.; Ramirez Alegria, S.; Borissova, J.; O'Leary, E.; Martins, F.; Herve, A.; Kuhn, M.; Kurtev, R.; Consuelo Amigo Fuentes, P.; Bonatto, C.; Minniti, D.

    2015-11-01

    We present the JHKs photometry extracted from the VVV (VISTA variables in the Via Lactea) survey for the cluster VVV CL041. The photometry extraction was performed by employing the VVV-SkZ pipeline's (Mauro et al., 2013RMxAA..49..189M) automated software based on ALLFRAME (Stetson, 1994PASP..106..250S). 2MASS photometry was used for absolute flux calibration in the J, H, and Ks bands, using stars with 12.5

  15. Optical/near-IR surface photometry of blue low surface brightness galaxies

    NASA Astrophysics Data System (ADS)

    Bergvall, Nils; Rönnback, Jari; Masegosa, Josefa; Östlin, Göran

    1999-01-01

    We present luminosity profiles, colour profiles and disk parameters based on near-infrared JHK surface photometry of a sample of blue low surface brightness galaxies (BLSBGs). The results are discussed along with previously obtained optical data. We find that the morphological properties in optical and near-IR are quite similar. The luminosity profiles have exponential shapes modified by a small central bulge or, below $calM u_{B,0}\\sim23 magnitudes arcsec^{-2}$, a trough. The blue LSBGs have scalelengths intermediate between normal LSB disks and gas rich dwarf galaxies. A correlation between scalelength and B-V colour is found for LSBGs in general. In comparison with normal late type disk galaxies our galaxies are bluer and smaller. At the same B scalelength, the two types differ in luminosity with 2 magnitudes, corresponding to a difference in mean star formation rate of a factor 5-10. Several photometric properties indicate that they contain very little dust and that, at the lowest surface brightnesses, the stellar population is homogeneous.

  16. Inferring Milky Way Structure from 2MASS-selected Carbon Stars

    NASA Astrophysics Data System (ADS)

    Skrutskie, M. F.; Reber, T. J.; Murphy, N. W.; Weinberg, M. D.

    2001-12-01

    We present a reconstructed view of the Milky Way disk using 40,000 carbon star candidates extracted from the Two Micron All Sky Survey (2MASS). These candidates can be selected with high reliability using a technique which distinguishes the intrinsically red colors of carbon stars (and other extreme AGB) from reddened stars in the Galactic plane using 2MASS photometry alone. The extracted sources serve as crude standard candles with a dispersion of 0.3 mag. The complete stellar bar and the far edge of the Galactic disk are evident in this analysis. We further infer parameters for the central bar and for disk scale lengths and scale heights using this population.

  17. Stellar photometry with big pixels

    SciTech Connect

    Buonanno, R.; Iannicola, G.; European Southern Observatory, Garching )

    1989-03-01

    A new software for stellar photometry in crowded fields is presented. This software overcomes the limitations present in a traditional package like ROMAFOT when the pixel size of the detector is comparable to the scale length of point images. This is the case, for instance, with the Hubble Space Telescope-Wide Field Camera and, partially, with the Planetary Camera. The numerical solution presented here is compared to the technical solution of obtaining more exposures of the same field, each shifted by a fraction of pixel. This software will be available in MIDAS. 11 refs.

  18. Differential photometry of magnetic faculae

    NASA Technical Reports Server (NTRS)

    Foukal, P.; Duvall, T., Jr.

    1985-01-01

    New observations extending the differential continuum photometry technique to the near-infrared are presented which demonstrate that the main factor determining the facular visibility near the solar disk center is the difference in H(-) opacity (and thus in penetration depth) between the continuum passbands. It is shown how the difference signal obtained depends on the temperature gradient difference between the two faculae and photosphere. The measured facular temperature gradient is compared with that given by empirical facular models based on Fraunhofer line observations, and with theoretical predictions. An explanation for the enhanced visibility of faculae against granular noise in the difference signal is suggested.

  19. UBV photometry of ER Vulpeculae

    NASA Astrophysics Data System (ADS)

    Srivastava, R. K.; Padalia, T. D.; Srivastava, J. B.

    1991-08-01

    UBV photometry of the RS CVn-type eclipsing binary system ER Vulpeculae has been presented. The period comes out to be 0.698093d. The average depths of primary and secondary minima are, respectively, 0.21 and 0.12m. The colors at various phases have been given. A dip is seen around phase 0.73P as was seen in the observations of Arevalo et al. (1988). Large scatter is present in the observations as noticed earlier, and may be due to activity of the components.

  20. Asteroid Analysis Using Lightcurve Photometry

    NASA Astrophysics Data System (ADS)

    Zimmerman, Jessica

    2011-10-01

    During the summer of 2011 data was taken of asteroid 3807 Pagels, a mid-sized asteroid located in the main asteroid belt in order to identify its rotational period. The asteroid 3807 Pagels is a poorly studied main belt asteroid that has little information recorded about its physical features. Time-series photometry of 3807 Pagels was obtained with a 16-inch telescope connected to a CCD camera located at the Texas A&M University - Commerce Observatory. CCD images were taken continuously with five minute exposure times through the standard broadband V filter. The data was then analyzed using the MPO Canopus program which utilized comparison stars within each CCD image to determine differential photometry and then generate a lightcurve for the asteroid. The final lightcurve did not show a complete rotational period for the asteroid. Thus, additional observations are needed in order to precisely determine 3807 Pagels rotational period. This research is the first steps of a long process of determining more information about the many mid-sized asteroids located in the asteroid belt for the potential of being able to classify these asteroids by their physical characteristics.

  1. The IC 5146 star forming complex and its surroundings with 2MASS, WISE and Spitzer

    NASA Astrophysics Data System (ADS)

    Nunes, N. A.; Bonatto, C.; Bica, E.

    2016-02-01

    Throughout the last decade sensitive infrared observations obtained by the Spitzer Space Telescope significantly increased the known population of YSOs associated with nearby molecular clouds. With such a census recent studies have characterized pre-main sequence stars (PMS) and determined parameters from different wavelengths. Given the restricted Spitzer coverage of some of these clouds, relative to their extended regions, these YSO populations may represent a limited view of star formation in these regions. We are taking advantage of mid-infrared observations from the NASA Wide Field Infrared Survey Explorer (WISE), which provides an all sky view and therefore full coverage of the nearby clouds, to assess the degree to which their currently known YSO population may be representative of a more complete population. We extend the well established classification method of the Spitzer Legacy teams to archived WISE observations. We have adopted 2MASS photometry as a "standard catalogue" for comparisons. Besides the massive embedded cluster IC 5146 we provide a multiband view of five new embedded clusters in its surroundings that we discovered with WISE. In short, the analysis involves the following for the presently studied cluster sample: (i) extraction of 2MASS/WISE/Spitzer photometry in a wide circular region; (ii) field-star decontamination to enhance the intrinsic Colour-magnitude diagram (CMD) morphology (essential for a proper derivation of reddening, age, and distance from the Sun); and (iii) construction of Colour-magnitude filters, for more contrasted stellar radial density profiles (RDPs).

  2. High Speed Photometry for BUSCA

    NASA Astrophysics Data System (ADS)

    Cordes, O.; Reif, K.

    The camera BUSCA (Bonn University Simultaneous CAmera) is a standard instrument at the 2.2m telescope at Calar Alto Observatory (Spain) since 2001. At the moment some modifications of BUSCA are planned and partially realised. One major goal is the replacement of the old thick CCDs in the blue, yellow-green, and near-infrared channels. The newer CCDs have better cosmetics and performance in sensitivity. The other goal is to replace the old "Heidelberg"-style controller with a newly designed controller with the main focus on high-speed readout and on an advanced windowing mechanism. We present a theoretical analysis of the new controller design and its advantage in high speed photometry of rapidly pulsating stars. As an example PG1605+072 was chosen which was observed with BUSCA before in 2001 and 2002.

  3. Photometry of late type stars

    NASA Technical Reports Server (NTRS)

    Doherty, L. R.

    1972-01-01

    Broad band filter photometry for 57 bright stars of spectral type A2 discussed with peak instrument responses at 3320, 2980, 2460 and 1910 A. The data include nearly all usable filter observations of G, K and M types. Sampling is nearly complete for A and F giants and supergiants, with the exception of Cepheid variables. The basic results presented are relative digital counting rates obtained with a field-stop aperture of 10 minutes of arc. Characteristics of the four filter-photometer combinations and errors are discussed. Some observations require substantial correction if they are to represent the visually brightest star in the field. These corrections and the effects of interstellar reddening are discussed. The adjusted counts are then used to construct color-color diagrams and are compared to the recent SAO grid of model atmospheres.

  4. WFPC2 Stellar Photometry with HSTphot

    NASA Technical Reports Server (NTRS)

    Dolphin, Andrew E.

    2000-01-01

    HSTphot, a photometry package designed to handle the undersampled PSFs found in WFPC2 images, is introduced and described, as well as some of the considerations that have to be made in order to obtain accurate PSF-fitting stellar photometry with WFPC2 data. Tests of HSTphot's internal reliability are made using multiple observations of the same field, and tests of external reliability are made by comparing with DoPHOT reductions of the same data. Subject headz'ngs: techniques: photometric

  5. CCD photometry of NGC 2419

    NASA Astrophysics Data System (ADS)

    Christian, C. A.; Heasley, J. N.

    1988-05-01

    CCD photometry of NGC 2419 has been compared to similar data for other metal-poor galactic globular clusters. Although NGC 2419 shares many characteristics with other outer-halo clusters (large tidal and core radius, low central surface brightness), the cluster is atypical of that population in other respects. The object appears to be a close analogy to metal-poor globulars located closer to the galactic center, and in particular the comparison to M15 shows that the color-magnitude diagrams of the two clusters are very similar. The two clusters are very similar in age and metallicity. The predominant difference between M15 and NGC 2419 is that the number of RR Lyraes is significantly smaller in the latter cluster, as well as a lack of an extreme blue tail to the horizontal branch. The observed distance modulus to NGC 2419 appears to be (m-M)V = 20.0±0.15, with a reddening E(B-V) = 0.11±0.05. Comparison to theoretical isochrones suggest the age of the cluster is 16 Gyr and supports the distance modulus found empirically. Oxygen-rich models (Fahlman, Richer, and VanderBerg 1985) and the new Yale models (Green, Demarque, and King 1987) were also examined.

  6. Meteor44 Video Meteor Photometry

    NASA Technical Reports Server (NTRS)

    Swift, Wesley R.; Suggs, Robert M.; Cooke, William J.

    2004-01-01

    Meteor44 is a software system developed at MSFC for the calibration and analysis of video meteor data. The dynamic range of the (8bit) video data is extended by approximately 4 magnitudes for both meteors and stellar images using saturation compensation. Camera and lens specific saturation compensation coefficients are derived from artificial variable star laboratory measurements. Saturation compensation significantly increases the number of meteors with measured intensity and improves the estimation of meteoroid mass distribution. Astrometry is automated to determine each image's plate coefficient using appropriate star catalogs. The images are simultaneously intensity calibrated from the contained stars to determine the photon sensitivity and the saturation level referenced above the atmosphere. The camera s spectral response is used to compensate for stellar color index and typical meteor spectra in order to report meteor light curves in traditional visual magnitude units. Recent efforts include improved camera calibration procedures, long focal length 'streak' meteor photometry and two-station track determination. Meteor44 has been used to analyze data from the 2001, 2002 and 2003 MSFC Leonid observational campaigns as well as several lesser showers. The software is interactive and can be demonstrated using data from recent Leonid campaigns.

  7. VizieR Online Data Catalog: Multiwavelength photometry of 34 galaxies (Rowlands+, 2014)

    NASA Astrophysics Data System (ADS)

    Rowlands, K.; Dunne, L.; Dye, S.; Aragon-Salamanca, A.; Maddox, S.; da Cunha, E.; Smith, D. J. B.; Bourne, N.; Eales, S.; Gomez, H. L.; Smail, I.; Alpaslan, M.; Clark, C. J. R.; Driver, S.; Ibar, E.; Ivison, R. J.; Robotham, A.; Smith, M. W. L.; Valiante, E.

    2014-03-01

    Photometry for 34 submillimetre galaxies (including 5 galaxies with poor quality SED fits rejected from the final sample) utilised in the paper from the compilation in Magnelli et al (2012A&A...539A.155M, hereafter M12), which were taken from blank field (sub)millimetre surveys (850-1200um) which have robust counterparts identified with deep radio, interferometric submillimetre and/or mid-infrared imaging. In GOODS-N all photometry shortwards of 3um is described in Berta et al. (2010A&A...518L..30B, 2011A&A...532A..49B) and includes PSF-matched photometry from HST ACS bviz (version 1.0), FLAMINGOS JHK, IRAC 3.6, 4.5, 5.8, 8.0um was obtained with the ConvPhot code and spectroscopic redshifts and U-band magnitudes from Barger et al. (2008, Cat. J/ApJ/689/687). Deep CFHT WirCAM K_s band photometry was taken from Wang et al. (2010, Cat. J/ApJS/187/251). We refer the reader to http://www2011.mpe.mpg.de/ir/Research/PEP/publicdatareleases.php?lang=en for details, but briefly, magnitudes with value +99.99 are non-detections. ConvPhot-derived magnitudes are negative if they are fainter than the 1-sigma noise level. In this case the absolute value of the magnitude (with a small correction to galactic extinction) corresponds to half their flux and their magnitude uncertainty is equal to 0.7526mag. The U-band magnitudes from Barger et al. (2008, Cat. J/ApJ/689/687) are -99.99 if a source was not matched. In some cases magnitudes are negative and not -99.99, see Barger et al (2008, Cat. J/ApJ/689/687) for details. WIRCam Ks magnitudes are -99.99 if an object was not matched. The 70um MIPS data in GOODS-N are from Magnelli et al. (2011, Cat. J/A+A/528/A35), negative flux values indicate an upper limit, with the absolute flux value equal to the 5σ upper limit computed from the 70um residual map. We list the uncertainties from both the residual map and Monte-Carlo simulations which includes an additional statistical contribution from confusion noise, see Magnelli et al. (2011

  8. VizieR Online Data Catalog: WISE and 2MASS photometry of M giant stars (Li+, 2016)

    NASA Astrophysics Data System (ADS)

    Li, J.; Smith, M. C.; Zhong, J.; Hou, J.; Carlin, J. L.; Newberg, H. J.; Liu, C.; Chen, L.; Li, L.; Shao, Z.; Small, E.; Tian, H.

    2016-08-01

    We cross-matched our LAMOST spectroscopically confirmed sample of M giants, M dwarfs, and QSOs (see section 2) to the ALLWISE Source Catalog in the NASA/IPAC Infrared Science Archive, using a search radius of 3". We also applied some cuts detailed in section 3. (1 data file).

  9. Differential Photometry at 1612 MHz

    NASA Astrophysics Data System (ADS)

    Lewis, B. Murray

    2009-01-01

    The 1612 MHz light curves of high latitude OH/IR stars have been observed for several years with the Arecibo 305m telescope, to derive the light-travel time diameter of their shells from the phase difference between their red and blue shifted peaks, and to look for secular evolution of their masers. However, direct intensity measurements are always limited by the extent to which the telescope's characteristics can be removed. These, in Arecibo's case, are subject to changes in the weight distribution about the structure over time, to the functioning of the vertical tie-down system, which can be interrupted by thunder storms, and by temperature-related zenith angle effects during daytime observations. Nevertheless, all of these limitations are neutralized when the ratio of the two peaks is used as the observed parameter. This form of differential photometry often results in clean light curves, though the ratio may still be perturbed by RFI, by interstellar scintillation, and more predictably by noise. The increased sensitivity of this observing mode readily detects (1) any differential evolution of the two masers, as well as (2) highlighting changes in masing gain between the two peaks around the pulsation cycle, that in turn are indicative of the operation of partially rather than fully saturated masers. In many of our light-curves there are abrupt changes in the ratio of the peak intensities at a constant pulsation phase. These are interpreted as being due to the onset of dust formation at that phase of the pulsation cycle, with a consequent abrupt change in the reprocessing of the stellar SED, and hence to an abrupt change in the maser pump. This is a feature of the Gray, Howe & Lewis (MN 364, 783 (2005)) maser model. Examples of these effects will be shown.

  10. Analysis of Multi-band Photometry of Violently Variable Gamma-Ray Sources

    NASA Astrophysics Data System (ADS)

    Kadowaki, Jennifer; Malkan, M. A.

    2013-01-01

    We studied the relationship between rapid variations in the jet intensities and changes in accretion disk activity of blazar subtype, Flat Spectrum Radio Quasar (FSRQ). Fifteen known FSRQs were specifically chosen for their prominent big blue bumps with redshifts near z=1, in order for the rest-frame UV to be redshifted into the blue-band pass. Flux changes for these 15 FSRQs were monitored for 15 observational nights in BVRI-bands and 20 nights in JHK-bands over a 12 month period using NASA's Fermi Gamma-ray Space Telescope, Lick Observatory's Nickel Telescope, and Kitt Peak National Observatory's 2.1 m Telescope. With 6.3’ x 6.3’ field of view for Nickel’s Direct Imaging Camera and 20’ x 20’ for Flamingos IR Imaging Spectrometer, approximately a half dozen, bright and non-variable stars were available to compare the concurrent changes in each of the quasar’s brightness. This process of differential photometry yielded photometric measurements of quasar brightness with 1-2% level precision. Light curves were then created for these 15 monitored quasars in optical, infrared, and gamma-ray energy bands. Dominating the redder emission spectrum due to non-thermal, synchrotron radiation and compton scattering of gamma-rays off high energy electrons, jet activity was compared to bluer spectral regions having strong accretion disk component with rest frame of approximately 2000 Angstroms. Most of the targeted FSRQs varied significantly over the 12 month monitoring period, with varying levels of fluctuations for each observed wavelength. Some correlations between gamma-ray and optical wavelengths were also present, which will be further discussed in the poster.

  11. Star-galaxy separation strategies for WISE-2MASS all-sky infrared galaxy catalogues

    NASA Astrophysics Data System (ADS)

    Kovács, András; Szapudi, István

    2015-04-01

    We combine photometric information of the Wide-Field Infrared Survey Explorer (WISE) and Two Micron All Sky Survey (2MASS) all-sky infrared data bases, and demonstrate how to produce clean and complete galaxy catalogues for future analyses. Adding 2MASS colours to WISE photometry improves star-galaxy separation efficiency substantially at the expense of losing a small fraction of the galaxies. We find that 93 per cent of the WISE objects within W1 < 15.2 mag have a 2MASS match, and that a class of supervised machine learning algorithms, support vector machines (SVM), are efficient classifiers of objects in our multicolour data set. We constructed a training set from the Sloan Digital Sky Survey PhotoObj table with known star-galaxy separation, and determined redshift distribution of our sample from the Galaxy and Mass Assembly spectroscopic survey. Varying the combination of photometric parameters input into our algorithm we show that W1WISE - J2MASS is a simple and effective star-galaxy separator, capable of producing results comparable to the multidimensional SVM classification. We present a detailed description of our star-galaxy separation methods, and characterize the robustness of our tools in terms of contamination, completeness, and accuracy. We explore systematics of the full sky WISE-2MASS galaxy map, such as contamination from moon glow. We show that the homogeneity of the full sky galaxy map is improved by an additional J2MASS < 16.5 mag flux limit. The all-sky galaxy catalogue we present in this paper covers 21 200 deg2 with dusty regions masked out, and has an estimated stellar contamination of 1.2 per cent and completeness of 70.1 per cent among 2.4 million galaxies with zmed ≈ 0.14. WISE-2MASS galaxy maps with well controlled stellar contamination will be useful for spatial statistical analyses, including cross-correlations with other cosmological random fields, such as the cosmic microwave background. The same techniques also yield a

  12. Deep near-infrared surface photometry and properties of Local Volume dwarf irregular galaxies

    NASA Astrophysics Data System (ADS)

    Young, T.; Jerjen, H.; López-Sánchez, Á. R.; Koribalski, B. S.

    2014-11-01

    We present deep H-band surface photometry and analysis of 40 Local Volume galaxies, a sample primarily composed of dwarf irregulars in the Cen A group, obtained using the Infrared Imager and Spectrograph 2 detector at the 3.9-m Anglo-Australian Telescope. We probe to a surface brightness of ˜25 mag arcsec-2, reaching a 40 times lower stellar density than the Two Micron All Sky Survey (2MASS). Employing extremely careful and rigorous cleaning techniques to remove contaminating sources, we perform surface photometry on 33 detected galaxies deriving the observed total magnitude, effective surface brightness and best-fitting Sérsic parameters. We make image quality and surface photometry comparisons to 2MASS and VISTA Hemisphere Survey demonstrating that deep targeted surveys are still the most reliable means of obtaining accurate surface photometry. We investigate the B - H colours with respect to mass for Local Volume galaxies, finding that the colours of dwarf irregulars are significantly varied, eliminating the possibility of using optical-near-infrared colour transformations to facilitate comparison to the more widely available optical data sets. The structure-luminosity relationships are investigated for our `clean' sample of dwarf irregulars. We demonstrate that a significant fraction of the Local Volume dwarf irregular population have underlying structural properties similar to both Local Volume and Virgo cluster dwarf ellipticals. Linear regressions to structure-luminosity relationships for the Local Volume galaxies and Virgo cluster dwarf ellipticals show significant differences in both slope and scatter around the established trend lines, suggesting that environment might regulate the structural scaling relationships of dwarf galaxies in comparison to their more isolated counterparts.

  13. The FIRST-2MASS Red Quasar Survey

    SciTech Connect

    Glikman, E; Helfand, D J; White, R L; Becker, R H; Gregg, M D; Lacy, M

    2007-06-28

    Combining radio observations with optical and infrared color selection--demonstrated in our pilot study to be an efficient selection algorithm for finding red quasars--we have obtained optical and infrared spectroscopy for 120 objects in a complete sample of 156 candidates from a sky area of 2716 square degrees. Consistent with our initial results, we find our selection criteria--J-K > 1.7,R-K > 4.0--yield a {approx} 50% success rate for discovering quasars substantially redder than those found in optical surveys. Comparison with UVX- and optical color-selected samples shows that {approx}> 10% of the quasars are missed in a magnitude-limited survey. Simultaneous two-frequency radio observations for part of the sample indicate that a synchrotron continuum component is ruled out as a significant contributor to reddening the quasars spectra. We go on to estimate extinctions for our objects assuming their red colors are caused by dust. Continuum fits and Balmer decrements suggest E(B-V) values ranging from near zero to 2.5 magnitudes. Correcting the K-band magnitudes for these extinctions, we find that for K {le} 14.0, red quasars make up between 25% and 60% of the underlying quasar population; owing to the incompleteness of the 2MASS survey at fainter K-band magnitudes, we can only set a lower limit to the radio-detected red quasar population of > 20-30%.

  14. VizieR Online Data Catalog: Spitzer and VRIJHK photometry of V582 Mon (Arulanantham+, 2016)

    NASA Astrophysics Data System (ADS)

    Arulanantham, N. A.; Herbst, W.; Cody, A. M.; Stauffer, J. R.; Rebull, L. M.; Agol, E.; Windemuth, D.; Marengo, M.; Winn, J. N.; Hamilton, C. M.; Mundt, R.; Johns-Krull, C. M.; Gutermuth, R. A.

    2016-07-01

    We have continued to obtain ground-based optical and near-infrared photometry over the last two years using A Novel Dual Imaging CAMera (ANDICAM) on the 1.3m telescope at Cerro-Tololo Inter-American Observatory (CTIO) in Chile. The instrument is operated by the SMARTS consortium. Data were collected almost nightly from 2013 October through 2014 April. Observations were resumed in 2014 September and continued until 2015 April. Each night, four 150s exposures were obtained in each of the three optical bands (VRI) along with 10-15 dithered exposures (30s each) in the near-infrared bands (JHK). All images have a 10.2'*10.2' field of view. The data acquisition and reduction processes are discussed briefly in Appendix A, and a more complete description is given by Windemuth & Herbst 2014 (cat. J/AJ/147/9). The VRIJHK magnitudes from the last two observing seasons have been added to the entire set of CCD data obtained since 1995, which is presented here as Table1. Images of KH 15D were collected with the InfraRed Array Camera (IRAC) on the Spitzer Space Telescope during six observational runs with five separate PI's spanning three distinct epochs since 2004 (2004 Mar 6 and 2004 Oct 08, PI Giovanni Fazio, Program ID=37; 2004 Oct 5-12 and 2005 Oct 21-29, PI Massimo Marengo, Program ID=3441; 2006 Mar 23-27, PI Eric Agol, Program ID=3469; 2008 Nov 1-2, PI Lucas A. Cieza, Program ID=50773). The fifth set of observations was obtained by the CSI 2264 team (PI=John R. Stauffer, Program ID=61027, 80040) as part of a large campaign to monitor young variable objects in NGC2264 (Cody et al. 2014, cat. J/AJ/147/82). These data were obtained over 28 consecutive days of observation in 2011 December (2011 Dec 3-2012 Jan 1). A final set of observations was obtained on eight nights between 2013 December and 2014 January (2013 Dec 22-2014 Jan 20, PI William Herbst, Program ID=90154, 90098). The full set of Spitzer photometry at all epochs is given in Table3. (2 data files).

  15. BVRIJHK photometry and proper motion analysis of NGC 6253 and the surrounding field

    NASA Astrophysics Data System (ADS)

    Montalto, M.; Piotto, G.; Desidera, S.; Platais, I.; Carraro, G.; Momany, Y.; de Marchi, F.; Recio-Blanco, A.

    2009-10-01

    Context: We present a photometric and astrometric catalog of 187 963 stars located in the field around the old super-metal-rich Galactic open cluster NGC 6253. The total field-of-view covered by the catalog is 34”×33”. In this field, we provide CCD BVRI photometry. For a smaller region close to the cluster's center, we also provide near-infrared JHK photometry. Aims: We analyze the properties of NGC 6253 by using our new photometric data and astrometric membership. Methods: In June 2004, we targeted the cluster during a 10 day multi-site campaign, which involved the MPG/ESO 2.2 m telescope with its wide-field imager and the Anglo-Australian 3.9 m telescope, equipped with the IRIS2 near-infrared imager. Archival CCD images of NGC 6253 were used to derive relative proper motions and to calculate the cluster membership probabilities. Results: We have refined the cluster's fundamental parameters, deriving (V_0-M_v)=11.15, E(B - V) = 0.15, E(V - I) = 0.25, E(V - J) = 0.50, and E(V - H) = 0.55. The color excess ratios obtained using both the optical and near infrared colors indicate a normal reddening law in the direction of NGC 6253. The age of NGC 6253 at 3.5 Gyr, determined from our best-fitting isochrone appears to be slightly older than the previous estimates. Finally, we estimated the binary fraction among the cluster members to be ~20%-30% and identified 11 blue straggler candidates. Based on observation made at the European Southern Observatory, La Silla, Chile and at the Anglo-Australian Observatory, Siding Spring, Australia. The catalog presented in this paper is only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/505/1129

  16. Detection of Terrestrial Planets Using Transit Photometry

    NASA Technical Reports Server (NTRS)

    Koch, David; Witteborn, Fred; Jenkins, Jon; Dunham, Edward; Boruci, William; DeVincenzi, Donald (Technical Monitor)

    2001-01-01

    Transit photometry detection of planets offers many advantages: an ability to detect terrestrial size planets, direct determination of the planet's size, applicability to all main-sequence stars, and a differential brightness change of the periodic signature being independent of stellar distance or planetary orbital semi-major axis. Ground and space based photometry have already been successful in detecting transits of the giant planet HD209458b. However, photometry 100 times better is required to detect terrestrial planets. We present results of laboratory measurements of an end-to-end photometric system incorporating all of the important confounding noise features of both the sky and a space based photometer including spacecraft jitter. In addition to demonstrating an instrumental noise of less than 10 ppm (an Earth transit of a solar-like star is 80 ppm), the brightnesses of individual stars were dimmed to simulate Earth-size transit signals. These 'transits' were reliably detected as part of the tests.

  17. Photometry of eight magnetic peculiar A stars

    NASA Astrophysics Data System (ADS)

    Adelman, Saul J.; Dukes, Robert J., Jr.; Pyper, Diane M.

    1992-07-01

    The paper presents the photometry of eight magnetic Ap stars 63 And, CU Vir, Beta CrB, Chi Ser, 52 Her, HD 111133, HD 147010, and HD 173650, most of which was obtained with the Phoenix 10-in. Automated Photoelectric Telescope of the Fairborn Observatory. Special attention is given to the results of period determinations, showing that the failure to establish better periods is often due to inaccuracies and gaps in the photometry. The data obtained for HD 147010 validates North's (1984) period of 3.9210 days.

  18. TRIPPy: Python-based Trailed Source Photometry

    NASA Astrophysics Data System (ADS)

    Fraser, Wesley C.; Alexandersen, Mike; Schwamb, Megan E.; Marsset, Michael E.; Pike, Rosemary E.; Kavelaars, JJ; Bannister, Michele T.; Benecchi, Susan; Delsanti, Audrey

    2016-05-01

    TRIPPy (TRailed Image Photometry in Python) uses a pill-shaped aperture, a rectangle described by three parameters (trail length, angle, and radius) to improve photometry of moving sources over that done with circular apertures. It can generate accurate model and trailed point-spread functions from stationary background sources in sidereally tracked images. Appropriate aperture correction provides accurate, unbiased flux measurement. TRIPPy requires numpy, scipy, matplotlib, Astropy (ascl:1304.002), and stsci.numdisplay; emcee (ascl:1303.002) and SExtractor (ascl:1010.064) are optional.

  19. Direct imaging photometry with the MOST satellite

    NASA Astrophysics Data System (ADS)

    Rowe, J. F.; Matthews, J. M.; Kuschnig, R.; Guenther, D. B.; Moffat, A. F. J.; Rucinski, S. M. R.; Sasselov, D.; Walker, G. A. H.; Weiss, W. W.

    Canada's first space telescope, MOST (Microvariablity and Oscillations of Stars) was successfully launched on June 30, 2003 with a primary mission to perform ultra-high-precision photometry to detect acoustic oscillations in solar-like stars. MOST has the ability to observe single fields for uninterrupted periods of up to two months and targets can be observed either through Fabry lens imaging or Direct imaging. This report reviews the Direct imaging capabilities of the MOST satellite and the extraction of accurate stellar photometry. MOST is a Canadian Space Agency mission, operated jointly by Dynacon, Inc., and the Universities of Toronto and British Columbia, with assistance from the University of Vienna.

  20. Spacewatch Taxonomic Photometry of Near-Earth Objects Detected by NEOWISE

    NASA Astrophysics Data System (ADS)

    Larsen, Jeffrey A.; McMillan, Robert S.; Scotti, James V.

    2014-11-01

    We have performed a program of multiband photometry for carefully selected Near-Earth Objects (NEOs) having NEOWISE mission determined diameters (Mainzer et al. 2011 http://adsabs.harvard.edu/abs/2011ApJ...743..156M ).Standardized high precision V-band photometry of such objects establishes the albedo near the peak of incident solar flux, which reckons in modeling their thermal properties. These observations are valuable since the delivery of asteroids from the main belt to Earth-crossing orbits depends on albedo, size, & composition. Measurements of mineralogical classes by means of taxonomic photometry can thus help refine understanding of the filtering involved in asteroid transport.Due to the faintness of the targets and time limitations, the program typically used BVRI photometry to classify the objects using Dandy et al. (2003). Although less accurate and potentially more ambiguous than the Bus-DeMeo or Tholen systems, it is significantly easier to obtain for faint asteroids but still allows sorting into major taxonomic groups.The poster presents results of the reductions to date, concentrating on four particular asteroids observed May 30-31, 2014 at the Steward 2.3 meter with full UBVRIz colors. Simultaneous ZY/JHK measurements were taken by UKIRT which will also be presented if available.(36183) V=19.18±0.05, U-B=0.41±0.05, B-V=0.86±0.05, V-R=0.50±0.05, V-I=0.85±0.04 is consistent with an S type on the Dandy system.(85628) V=18.54±0.01, U-B=0.42±0.03, B-V=0.86±0.01, V-R=0.48±0.02, V-I=0.83±0.02, consistent with an S type.(85989) V=17.46±0.06, U-B=0.40±0.08, B-V=0.75±0.08, V-R=0.49±0.08, V-I=0.80±0.06 is consistent with an C type.(162181) V=18.59+/-0.01, U-B=0.44+/-0.02, B-V=0.88+/-0.01, V-R=0.48+/-0.01, V-I=0.87+/-0.01, consistent with an S type.Larsen acknowledges support from the USNA Kinnear Fellowship. Spacewatch was/is supported by JPL subcontract 100319 (2010-2011), NASA/NEOO grants NNG06GJ42G, NNX11AB52G, NNX12AG11G, NNX13AP99G, NNX14

  1. eta Carinae: physical information from photometry

    NASA Astrophysics Data System (ADS)

    van Genderen, A. M.; de Groot, M.; Sterken, C.

    2001-06-01

    The very first physical information one can get from optical photometry is that eta Car is variable. Figure 1 shows the light curve from 1600 to 2000. Most reseachers agree with the main interpretations of the various features as shown by the light curve. The eruptive phases are called S Dor- (SD-) eruptions as opposed to the S Dor- (SD-) phases, which are responsible for the oscillating light variations (due to slow pulsations) with a time-scale of years (van Genderen 2001). The rising trend after 1935 is called the 'secular rise' and is mainly due to a decrease of circumstellar extinction, i.e. a decrease of self-extinction by the expanding Homunculus. A model for the trend of the decrease fits the time interval 1935-2000 satisfactorily (van Genderen et al. 1994, and see dotted curve in Figure 1 presented here). The optical (and near-IR) photometry of eta Car is hampered by the fact that only integrated photometry of the whole bipolar nebula is possible. However, we have luck: the nebula is mainly a reflection nebula. Thus, in analogy with a Chinese lantern: if the flame flickers, the integrated light flickers as well. Therefore, it is still possible to extract from the integrated photometry, important physical characteristics of the variable star, although heavily veiled by dust and gas. The effect of smearing out by reflections in the homunculus is presumably small, see discussion in van Genderen et al. (1999).

  2. OAUNI photometry of ASASSN-16hw

    NASA Astrophysics Data System (ADS)

    Pereyra, A.; Ricra, J.; Zevallos, M.

    2016-09-01

    We report optical photometry of Type Ia SN ASASSN-16hw (=SN 2016ekt, ATel #9278, ATel #9289, ATel #9300) on 2016-08-06 (UT) gathered with the OAUNI 51cm telescope (Pereyra et al. 2015;arXiv:1512.03104) at Huancayo Observatory, Peru.

  3. Photometry of Faint Wide Doubles in Hydra

    NASA Astrophysics Data System (ADS)

    Knapp, Wilfried; Thuemen, Chris; Gould, Ross

    2015-11-01

    Images of several double stars in Hydra published on the "Double Star Imaging Project" Yahoo Group page suggest magnitude issues compared with the corresponding WDS catalog data per end of 2014. Taking additional images with V and B filters enabled photometry for these pairs, suggesting significant corrections to the old data in WDS.

  4. PHOTOMETRYPIPELINE - An Automated Pipeline for Calibrated Photometry

    NASA Astrophysics Data System (ADS)

    Mommert, Michael; Moskovitz, Nicholas; Trilling, David E.

    2016-10-01

    Telescopes acquire massive amounts of imaging data every night. The goal of a large fraction of these observations is to obtain calibrated photometry for point sources - stars or moving Solar System targets - in different filters.We present PHOTOMETRYPIPELINE (PP, github.com/mommermi/photometrypipeline), an automated pipeline to obtain calibrated photometry from imaging data. PP is an open-source Python 2.7 software suite that provides image registration, aperture photometry, photometric calibration, and target identification with only minimal human interaction. For image registration, PP utilizes Source Extractor (Bertin & Arnouts 1996, A&AS, 117) and SWARP (Bertin et al. 2002, ASP Conf. S., 228) to find a plate solution for each frame, providing accurate target astrometry. Circular aperture photometry is performed using Source Extractor; an optimum aperture radius is identified using a curve-of-growth analysis. Photometric calibration is obtained through matching the background source catalog with star catalogs with reliable photometry (e.g., SDSS, URAT-1) in an iterative process; magnitude zeropoint accuracies are usually of the order of 0.03 mag, or better. Final calibrated photometry for each field source is written into a queriable database; target photometry is extracted from this database. Moving targets are identified using JPL Horizons (Giorgini et al. 1996, BAAS, 28) ephemerides. Image combination capabilities (using SWARP, Bertin 2006, ASP Conf. S., 112) are also available to improve the target's signal.PP is well-suited for data covering a few square arcminutes of the sky due to its dependence on background sources for registration and calibration. PP can be run on Unix-based systems on a simple desktop machine and is capable of realtime data analysis. PP has been developed for observations of moving targets, but can also be used on other observations. Efforts to improve the sky coverage for phometric calibration are in progress. Also, a module will be

  5. Precision Multiband Photometry with a DSLR Camera

    NASA Astrophysics Data System (ADS)

    Zhang, M.; Bakos, G. Á.; Penev, K.; Csubry, Z.; Hartman, J. D.; Bhatti, W.; de Val-Borro, M.

    2016-03-01

    Ground-based exoplanet surveys such as SuperWASP, HAT Network of Telescopes (HATNet), and KELT have discovered close to two hundred transiting extrasolar planets in the past several years. The strategy of these surveys is to look at a large field of view and measure the brightnesses of its bright stars to around half a percent per point precision, which is adequate for detecting hot Jupiters. Typically, these surveys use CCD detectors to achieve high precision photometry. These CCDS, however, are expensive relative to other consumer-grade optical imaging devices, such as digital single-lens reflex cameras (DSLRs). We look at the possibility of using a DSLR camera for precision photometry. Specifically, we used a Canon EOS 60D camera that records light in three colors simultaneously. The DSLR was integrated into the HATNet survey and collected observations for a month, after which photometry was extracted for 6600 stars in a selected stellar field. We found that the DSLR achieves a best-case median absolute deviation of 4.6 mmag per 180 s exposure when the DSLR color channels are combined, and 1000 stars are measured to better than 10 mmag (1%). Also, we achieve 10 mmag or better photometry in the individual colors. This is good enough to detect transiting hot Jupiters. We performed a candidate search on all stars and found four candidates, one of which is KELT-3b, the only known transiting hot Jupiter in our selected field. We conclude that the Canon 60D is a cheap, lightweight device capable of useful photometry in multiple colors.

  6. GASPS Photometry of the Tucana-Horologium Association

    NASA Technical Reports Server (NTRS)

    Roberge, Donaldson J.; Roberge, Aki

    2010-01-01

    The GASPS Open Time Key Programme on Herschel represents a new opportunity to sensitively probe protoplanetary and debris disks at far-IR wavelengths. We present preliminary PACS 70 and 160 micron photometry of eighteen stars in the 30 Myr-old Tucana-Horologium association. Of these eighteen, eight were detected in the 70 micron band. Four of these eight were also detected in the 160 micron band. We constructed SEDs for these systems using optical data from Hipparcos (B and V), near-IR data from 2MASS (J, H, and K), mid-IR data from IRAS and Spitzer MIPS (12 and 24 microns, respectively), and the new far-IR data from PACS. For the stars showing IR excess emission, we fit simple single-temperature blackbody curves to the IR excess in order to determine the rough dust abundances and temperatures. Dust observations at these wavelengths will also be important for comparison with upcoming Herschel PACS spectra that will search for gas in the disks. Our goal is to determine or limit the ever-allusive gas-to-dust ratio for these disk systems.

  7. Accuracy of stellar parameters determined from multicolor photometry

    NASA Astrophysics Data System (ADS)

    Sichevskij, S. G.; Mironov, A. V.; Malkov, O. Yu.

    2014-04-01

    The development and application of new methods for intelligent analysis and extraction of information from digital sky surveys carried out in various spectral domains have now become a popular field in astrophysical research and, in particular, in stellar studies. Modern large-scale photometric surveys provide data for 105-106 relatively faint objects, and the lack of spectroscopic data can be compensated by the cross identification of the objects followed by an analysis of all catalogued photometric data. In this paper we investigate the possibility of determining the effective temperature, surface gravity, total extinction, and the total-to-selective extinction ratio based on the photometry provided in the 2MASS, SDSS, and GALEX surveys, and estimate the accuracy of the inferred parameters. We use a library of theoretical spectra to compute the magnitudes of stars in the photometric bands of the above surveys for various sets of input parameters. We compare the differences between the computed magnitudes with the errors of the corresponding surveys. We find that stellar parameters can be computed over a sizable domain of the parameter space. We estimate the accuracy of the resulting parameters. We show that the presence of far-ultraviolet data in the available set of observed magnitudes increases the accuracy of the inferred parameters.

  8. Mapping the Inner Halo of the Galaxy with 2MASS-Selected Horizontal-Branch Candidates

    NASA Astrophysics Data System (ADS)

    Brown, Warren R.; Geller, Margaret J.; Kenyon, Scott J.; Beers, Timothy C.; Kurtz, Michael J.; Roll, John B.

    2004-03-01

    We use Two Micron All Sky Survey (2MASS) photometry to select blue horizontal-branch (BHB) candidates covering the sky, |b|>15°. A 12.52MASS catalog. We show that a -0.20<(J-H)0<0.10, -0.10<(H-K)0<0.10 color-selected sample of stars is 65% complete for BHB stars and is composed of 47% BHB stars. We apply this photometric selection to the full 2MASS catalog and see no spatial overdensities of BHB candidates at high Galactic latitude, |b|>50°. We insert simulated star streams into the data and conclude that the high Galactic latitude BHB candidates are consistent with having no ~5° wide star stream with density greater than 0.33 objects deg-2 at the 95% confidence level. The absence of observed structure suggests that there have been no major accretion events in the inner halo in the last few Gyr. However, at low Galactic latitudes a two-point angular correlation analysis reveals structure on angular scales θ<~1°. This structure is apparently associated with stars in the thick disk and has a physical scale of 10-100 pc. Interestingly, such structures are expected by cosmological simulations that predict the majority of the thick disk may arise from accretion and disruption of satellite mergers.

  9. Surveying the Galactic Halo with 2MASS-Selected Horizontal Branch Candidates

    NASA Astrophysics Data System (ADS)

    Brown, W. R.; Geller, M. J.; Kenyon, S. J.; Beers, T. C.; Kurtz, M. J.; Roll, J. B.

    2003-12-01

    We use 2MASS photometry to select blue horizontal branch (BHB) candidates covering the sky |b| > 15o. A 12.5 < J0 < 15.5 sample of BHB stars traces the thick disk and inner halo to d⊙ ≃ 9 kpc, with a density 3-5 times that of M giant stars. We base our sample selection strategy on the Century Survey Galactic Halo Project, a survey that provides a complete, spectroscopically-identified sample of blue stars to a similar depth as the 2MASS catalog. We show that a -0.20 < (J-H)0 < 0.10, -0.10 < (H-K)0 < 0.10 color-selected sample of stars is 65% complete for BHB stars, and is composed of 47% BHB stars. We apply this photometric selection to the full 2MASS catalog, and see no spatial overdensities of BHB candidates at high Galactic latitude |b| > 50o. We insert simulated star streams into the data and conclude that the high Galactic latitude BHB candidates are consistent with having no ˜ 5o wide star stream with density greater than 0.33 objects deg-2 at the 95% confidence level. The absence of structure suggests there have been no major accretion events in the inner halo in the last few Gyr. However, at low Galactic latitudes a two-point angular correlation analysis reveals structure on angular scales θ ≲ 1o. This structure is apparently associated with stars in the thick disk, and has a physical scale of 10-100 pc. One possible explanation for this structure is provided by cosmological simulations that predict the majority of the thick disk may arise from accretion and disruption of satellite mergers.

  10. VizieR Online Data Catalog: Photometry and proper motions in Praesepe (Wang+, 2014)

    NASA Astrophysics Data System (ADS)

    Wang, P. F.; Chen, W. P.; Lin, C. C.; Pandey, A. K.; Huang, C. K.; Panwar, N.; Lee, C. H.; Tsai, M. F.; Tang, C.-H.; Goldman, B.; Burgett, W. S.; Chambers, K. C.; Draper, P. W.; Flewelling, H.; Grav, T.; Heasley, J. N.; Hodapp, K. W.; Huber, M. E.; Jedicke, R.; Kaiser, N.; Kudritzki, R.-P.; Luppino, G. A.; Lupton, R. H.; Magnier, E. A.; Metcalfe, N.; Monet, D. G.; Morgan, J. S.; Onaka, P. M.; Price, P. A.; Stubbs, C. W.; Sweeney, W.; Tonry, J. L.; Wainscoat, R. J.; Waters, C.

    2016-08-01

    Data used in this study include photometry and proper motion measurements within a 5° radius around the Praesepe center (R.A.=08h40m, decl.=+19°42', J2000). Archival data were taken from the 2MASS Point Sources Catalog (2MASS; cat. II/246), PPMXL (Roeser et al. 2010, cat. I/317), and Panoramic Survey Telescope And Rapid Response (Pan-STARRS). Pan-STARRS is a wide-field (7deg2) imaging system, with a 1.8m, f/4.4 telescope, equipped with a 1.4 giga-pixel camera. The prototype (PS1), located atop Haleakala, Maui, USA, has been patrolling the entire sky north of -30° declination since mid-2010 with a combination of gP1, rP1, iP1, zP1, and yP1 bands. The PS1 filters differ slightly from those of the SDSS. The gP1 filter extends 20nm redward of gSDSS for greater sensitivity and lower systematics for photometric redshift estimates. SDSS has no corresponding y filter (Tonry et al. 2012, cat. J/ApJ/750/99). Upon the completion of its 3.5yr mission by early 2014, PS1 will provide reliable photometry and astrometry. Table1 lists the properties of the 1040 candidates. (1 data file).

  11. Lightcurve Photometry Opportunities: 2016 October-December

    NASA Astrophysics Data System (ADS)

    Warner, Brian D.; Harris, Alan W.; Durech, Josef; Benner, Lance A. M.

    2016-10-01

    We present lists of asteroid photometry opportunities for objects reaching a favorable apparition and having either none or poorly-defined lightcurve parameters. Additional data on these objects will help with shape and spin axis modeling via lightcurve inversion. We also include lists of objects that will be the target of radar observations. Lightcurves for these objects can help constrain pole solutions and/or remove rotation period ambiguities that might not come from using radar data alone.

  12. WISE Photometry for 400 Million SDSS Sources

    NASA Astrophysics Data System (ADS)

    Lang, Dustin; Hogg, David W.; Schlegel, David J.

    2016-02-01

    We present photometry of images from the Wide-Field Infrared Survey Explorer (WISE) of over 400 million sources detected by the Sloan Digital Sky Survey (SDSS). We use a “forced photometry” technique, using measured SDSS source positions, star-galaxy classification, and galaxy profiles to define the sources whose fluxes are to be measured in the WISE images. We perform photometry with The Tractor image modeling code, working on our “unWISE” coaddds and taking account of the WISE point-spread function and a noise model. The result is a measurement of the flux of each SDSS source in each WISE band. Many sources have little flux in the WISE bands, so often the measurements we report are consistent with zero given our uncertainties. However, for many sources we get 3σ or 4σ measurements; these sources would not be reported by the “official” WISE pipeline and will not appear in the WISE catalog, yet they can be highly informative for some scientific questions. In addition, these small-signal measurements can be used in stacking analyses at the catalog level. The forced photometry approach has the advantage that we measure a consistent set of sources between SDSS and WISE, taking advantage of the resolution and depth of the SDSS images to interpret the WISE images; objects that are resolved in SDSS but blended together in WISE still have accurate measurements in our photometry. Our results, and the code used to produce them, are publicly available at http://unwise.me.

  13. Lightcurve Photometry Opportunities: 2016 July-September

    NASA Astrophysics Data System (ADS)

    Warner, Brian D.; Harris, Alan W.; Durech, Josef; Benner, Lance A. M.

    2016-07-01

    We present lists of asteroid photometry opportunities for objects reaching a favorable apparition and having either none or poorly-defined lightcurve parameters. Additional data on these objects will help with shape and spin axis modeling via lightcurve inversion. We also include lists of objects that will be the target of radar observations. Lightcurves for these objects can help constrain pole solutions and/or remove rotation period ambiguities that might not come from using radar data alone.

  14. Optical photometry using Bradford robotic telescope

    NASA Astrophysics Data System (ADS)

    Seal Braun, P.; Baruch, J. E. F.

    2009-06-01

    The Bradford Robotic Telescope (BRT) is located on Mount Teide at Tenerife and is working, taking observations since 2003. It is a fully automated telescope. The hardware and software used for the working of the telescope are described here. Twenty four BL Lac objects are observed since 2005 and magnitudes of the objects are calculated. We describe in this paper the working of BRT and optical BVR photometry of BL Lac objects, observed during 2005-2007.

  15. Variable Star Photometry at West Challow Observatory

    NASA Astrophysics Data System (ADS)

    Boyd, D.

    2007-05-01

    This paper describes the facilities and observing programme of a small personal observatory set up in the UK for CCD photometry of variable stars. Its development has been driven by the belief that committed amateurs can make a valuable scientific contribution to the study of variable stars. Observing projects carried out at WCO are described including examples of Pro-Am collaboration and contributions to the observing programmes of the BAAVSS, AAVSO and CBA.

  16. 100 years of photometry and radiometry

    NASA Astrophysics Data System (ADS)

    Hardis, Jonathan E.

    2001-06-01

    Measurement of light is an old subject, though the past 100 years have seen significant advances. 100 years ago, photometry - the art and science of measuring light as it is perceived by people - had the greater technological importance. Even today SI (the metric system) retains a base unit for photometry, the candela. However, early work at NBS included pivotal projects in the field of radiometry - the measurement of the physical characteristics of light. These included the validation of Planck's newly-minted theory of blackbody radiation, determining the radiation constants with good accuracy, and the definitive analysis of the spectral responsivity of human vision, so as to relate photometry to radiometry. This latter work has only increased in importance over the past 75 years as the definition of the candela has changed and improved. Today, NIST makes radiometric, and hence photometric measurements, with unprecedented precision. Cryogenic radiometers based on the principle of electrical substitution measure optical flux with uncertainties of 0.02%. Additional facilities enable measurement of spectral responsivity, spectral radiance, and spectral irradiance. Novel detectors, such as light-traps, allow the best accuracy to be transferred from the primary standards to routinely-used instruments and to calibration customers. Filtered detectors are used to realize photometric scales, radiation temperature scales, and other specialized measurements. Indeed, the story of the metrology of light is the story of continuous improvement, both driven by and enabled by advances in technology. We touch upon some of these as a prelude to the other talks in this Conference.

  17. Surface photometry of WINGS galaxies with GASPHOT

    NASA Astrophysics Data System (ADS)

    D'Onofrio, M.; Bindoni, D.; Fasano, G.; Bettoni, D.; Cava, A.; Fritz, J.; Gullieuszik, M.; Kjærgaard, P.; Moretti, A.; Moles, M.; Omizzolo, A.; Poggianti, B. M.; Valentinuzzi, T.; Varela, J.

    2014-12-01

    Aims: We present the B, V, and K band surface photometry catalogs obtained by running the automatic software GASPHOT on galaxies from the WINGS cluster survey with isophotal areas larger than 200 pixels. The catalogs can be downloaded at the Centre de Données Astronomiques de Strasbourg. Methods: The luminosity growth curves of stars and galaxies in a given catalog relative to a given cluster image were obtained simultaneously by slicing the image with a fixed surface brightness step in several SExtractor runs. Then, using a single Sersic law convolved with a space-varying point spread function (PSF), GASPHOT performed a simultaneous χ2 best-fit of the major- and minor-axis luminosity growth curves of galaxies. We outline the GASPHOT performances and compare our surface photometry with that obtained by SExtractor, GALFIT, and GIM2D. This analysis is aimed at providing statistical information about the accuracy that is generally achieved by the softwares for automatic surface photometry of galaxies. Results: The GASPHOT catalogs provide the parameters of the Sersic law that fit the luminosity profiles for each galaxy and for each photometric band. They are the sky coordinates of the galaxy center (RA, Dec), the total magnitude (m), the semi-major axis of the effective isophote (Re), the Sersic index (n), the axis ratio (b/a), and a flag parameter (QFLAG) that generally indicates the fit quality. The WINGS-GASPHOT database includes 41 463 galaxies in the B band, 42 275 in the V band, and 71 687 in the K band. The bright early-type galaxies have higher Sersic indices and larger effective radii, as well as redder colors in their center. In general, the effective radii increase systematically from the K to the V and B band. Conclusions: The GASPHOT photometry agrees well with the surface photometry obtained by GALFIT and GIM2D, and with the aperture photometry provided by SExtractor. In particular, the direct comparison of structural parameters derived by different

  18. Photometry and polarimetry of V 1057 Cygni.

    NASA Technical Reports Server (NTRS)

    Rieke, G.; Lee, T.; Coyne, G.

    1972-01-01

    Evaluation of extensive photometric and polarimetric data over a six-month interval for V 1057 Cyg. The polarization appears to be constant and of interstellar origin; the photometry, which extends nearly six octaves from the ultraviolet to 22 microns in the infrared, indicates that the total observed luminosity is decreasing - having now declined about 10% from its earlier level. A model characterized by two circumstellar shells which absorb and reradiate short-wavelength stellar flux from an underlying A1-type star provides the best fit to the observational data. The present variability, however, cannot be due to circumstellar activity, but appears to originate in the star itself.

  19. V photometry of Titania, Oberon, and Triton

    SciTech Connect

    Goguen, J.D.; Hammel, H.B.; Brown, R.H.

    1989-02-01

    The phase angle and orbital brightness variations of Titania, Oberon, and Triton are presently obtained through analysis of V filter photometry obtained at Mauna Kea in 1982-1983. While Titania and Oberon exhibit magnitude variations with phase angle comparable to those of low-to-moderate albedo asteroids observed within several deg of opposition, Triton's phase variation is distinctly different from these and has a phase coefficient consistent with either a high-albedo regolith or an optically thick nonparticulate scattering layer (perhaps an atmosphere, or an ocean). A low-albedo regolith cannot on the strength of these data be ruled out, however. 39 references.

  20. The RINGS Survey: Optical Broadband Photometry

    NASA Astrophysics Data System (ADS)

    Kuzio de Naray, Rachel; Mitchell, Carl; Spekkens, Kristine; Sellwood, Jerry; Williams, Ted

    2016-01-01

    We have targeted a sample of 19 nearby spiral galaxies, the RSS Imaging and Spectroscopy Nearby Galaxy Survey (RINGS), for detailed study of their mass distributions. We have obtained Fabry-Perot Halpha velocity fields using the Southern African Large Telescope (SALT), 21-cm HI observations using the Very Large Array (VLA), and optical broadband BVRI photometry using the CTIO 0.9m and KPNO 2.1m telescopes. We present the results of the photometric component of the survey including multicolor images, surface brightness profiles, and DiskFit structural models.

  1. New BVR Photometry of BL Camelopardalis

    NASA Astrophysics Data System (ADS)

    Joner, Michael D.

    2015-01-01

    New BVR photometry of the SX Phe star BL Camelopardalis has been secured with the 0.9 m reflector at the BYU West Mountain Observatory. The new data have been used to determine times of maximum light, standardize light curves in each of the three filters, and examine the frequencies that are currently detectable in the light curves from a single location.We acknowledge the Brigham Young University College of Physical and Mathematical Sciences as well as the Department of Physics and Astronomy for continued support of this and other research efforts currently being done at the West Mountain Observatory.

  2. Time Series Photometry of KZ Lacertae

    NASA Astrophysics Data System (ADS)

    Joner, Michael D.

    2016-01-01

    We present BVRI time series photometry of the high amplitude delta Scuti star KZ Lacertae secured using the 0.9-meter telescope located at the Brigham Young University West Mountain Observatory. In addition to the multicolor light curves that are presented, the V data from the last six years of observations are used to plot an O-C diagram in order to determine the ephemeris and evaluate evidence for period change. We wish to thank the Brigham Young University College of Physical and Mathematical Sciences as well as the Department of Physics and Astronomy for their continued support of the research activities at the West Mountain Observatory.

  3. Near Infrared Photometry of Nova Del 2013

    NASA Astrophysics Data System (ADS)

    Cass, C. A.; Carlon, L. R.; Corgan, T. D.; Dykhoff, A. D.; Gehrz, D. R.; Shenoy, P. D.

    2013-08-01

    Subjects: Infra-Red, Nova We report RIJHKLM photometry of Nova Del 2013 taken on August 28.13 UT using an As:Si bolometer mounted on the 0.76-m infrared telescope of the University of Minnesota's O'Brien Observatory (Marine on St. Croix, Minnesota, USA). Vega (alpha Lyrae) was used as the standard star. On this date we find: R = 5.6 +/- 0.1, I = 5.2 +/- 0.1, J = 4.5 +/- 0.1, H = 4.7 +/- 0.1, K = 4.7 +/- 0.1, L = 3.3 +/- 0.2, M = +1.8 +/- 0.3.

  4. SPHOTOM - Package for an Automatic Multicolour Photometry

    NASA Astrophysics Data System (ADS)

    Parimucha, Š.; Vaňko, M.; Mikloš, P.

    2012-04-01

    We present basic information about package SPHOTOM for an automatic multicolour photometry. This package is in development for the creation of a photometric pipe-line, which we plan to use in the near future with our new instruments. It could operate in two independent modes, (i) GUI mode, in which the user can select images and control functions of package through interface and (ii) command line mode, in which all processes are controlled using a main parameter file. SPHOTOM is developed as a universal package for Linux based systems with easy implementation for different observatories. The photometric part of the package is based on the Sextractor code, which allows us to detect all objects on the images and perform their photometry with different apertures. We can also perform astrometric solutions for all images for a correct cross-identification of the stars on the images. The result is a catalogue of all objects with their instrumental photometric measurements which are consequently used for a differential magnitudes calculations with one or more comparison stars, transformations to an international system, and determinations of colour indices.

  5. TRIPPy: Trailed Image Photometry in Python

    NASA Astrophysics Data System (ADS)

    Fraser, Wesley; Alexandersen, Mike; Schwamb, Megan E.; Marsset, Michaël; Pike, Rosemary E.; Kavelaars, J. J.; Bannister, Michele T.; Benecchi, Susan; Delsanti, Audrey

    2016-06-01

    Photometry of moving sources typically suffers from a reduced signal-to-noise ratio (S/N) or flux measurements biased to incorrect low values through the use of circular apertures. To address this issue, we present the software package, TRIPPy: TRailed Image Photometry in Python. TRIPPy introduces the pill aperture, which is the natural extension of the circular aperture appropriate for linearly trailed sources. The pill shape is a rectangle with two semicircular end-caps and is described by three parameters, the trail length and angle, and the radius. The TRIPPy software package also includes a new technique to generate accurate model point-spread functions (PSFs) and trailed PSFs (TSFs) from stationary background sources in sidereally tracked images. The TSF is merely the convolution of the model PSF, which consists of a moffat profile, and super-sampled lookup table. From the TSF, accurate pill aperture corrections can be estimated as a function of pill radius with an accuracy of 10 mmag for highly trailed sources. Analogous to the use of small circular apertures and associated aperture corrections, small radius pill apertures can be used to preserve S/Ns of low flux sources, with appropriate aperture correction applied to provide an accurate, unbiased flux measurement at all S/Ns.

  6. VizieR Online Data Catalog: I photometry of very low mass ONC stars (Rodriguez-Ledesma+, 2009)

    NASA Astrophysics Data System (ADS)

    Rodriguez-Ledesma, M. V.; Mundt, R.; Eisloeffel, J.

    2009-06-01

    Table 1 lists the 2908 very low mass objects in the Orion Nebula Cluster with magnitudes between 14-21mag in I band for which accurate photometry was performed. It contains the position, brightness and type of variability of these stars, as well as 2MASS counterparts when available. Table 2 lists the 487 objects found to be periodic in this study, for which their brightness, period and peak-to-peak amplitudes a re given, as well as periods measured in Herbst et al. 2002 (Cat. J/A+A/396/513) when available. (2 data files).

  7. Extinctions and Distances of Dark Clouds from Ugrijhk Photometry of Red Clump Giants: the North America and Pelican Nebulae Complex

    NASA Astrophysics Data System (ADS)

    Straižys, V.; Laugalys, V.

    A possibility of applying 2MASS J, H, Ks, IPHAS r, i and MegaCam u, g photometry of red giants for determining distances to dark clouds is investigated. Red clump giants with a small admixture of G5--K1 and M2--M3 stars of the giant branch can be isolated and used in determining distances to separate clouds or spiral arms. Interstellar extinctions of background red giants can be also used for mapping dust surface density in the cloud.

  8. TERMS PHOTOMETRY OF KNOWN TRANSITING EXOPLANETS

    SciTech Connect

    Dragomir, Diana; Kane, Stephen R.; Ciardi, David R.; Gelino, Dawn M.; Payne, Alan; Ramirez, Solange V.; Von Braun, Kaspar; Wyatt, Pamela; Pilyavsky, Genady; Mahadevan, Suvrath; Wright, Jason T.; Zachary Gazak, J.; Rabus, Markus

    2011-10-15

    The Transit Ephemeris Refinement and Monitoring Survey conducts radial velocity and photometric monitoring of known exoplanets in order to refine planetary orbits and predictions of possible transit times. This effort is primarily directed toward planets not known to transit, but a small sample of our targets consists of known transiting systems. Here we present precision photometry for six WASP (Wide Angle Search for Planets) planets acquired during their transit windows. We perform a Markov Chain Monte Carlo analysis for each planet and combine these data with previous measurements to redetermine the period and ephemerides for these planets. These observations provide recent mid-transit times which are useful for scheduling future observations. Our results improve the ephemerides of WASP-4b, WASP-5b, and WASP-6b and reduce the uncertainties on the mid-transit time for WASP-29b. We also confirm the orbital, stellar, and planetary parameters of all six systems.

  9. Photoelectric photometry of comet Kohoutek (1973f)

    NASA Technical Reports Server (NTRS)

    Kohoutek, L.

    1976-01-01

    Comet Kohoutek was observed with the 50 cm (f/15) reflecting telescope of the European Southern Observatory, La Silla, Chile, on fourteen nights between January 16 and 30, when the heliocentric and geocentric distances of the comet were r=0.66 - 1.00 A.U. and delta=0.81 - 0.96 A.U., respectively. The 40 inch and 80 inch diaphragms were used for the photometry of the cometary head in the UBV system and with six interference filters. The atmospheric conditions were good but the accuracy of observations was low due to large extinction and twilight. The mean error of one measurement of log F in all but Na 5893 A filters can be estimated at plus or minus 0.02, whereas the accuracy through the Na filter was substantially lower.

  10. Homogeneous photometry and star counts in the field of 9 Galactic star clusters

    NASA Astrophysics Data System (ADS)

    Seleznev, A. F.; Carraro, G.; Costa, E.; Loktin, A. V.

    2010-01-01

    We present homogeneous V, I CCD photometry of nine stellar fields in the two inner quadrants of the Galactic plane. The lines-of-view to most of these fields aim in the direction of the very inner Galaxy, where the Galactic field is very dense, and extinction is high and patchy. Our nine fields are, according to several catalogs, centred on Galactic star clusters, namely Trumpler 13, Trumpler 20, Lynga 4, Hogg 19, Lynga 12, Trumpler 25, Trumpler 26, Ruprecht 128, and Trumpler 34. Apart from their coordinates, and in some cases additional basic data (mainly from the 2MASS archive), their properties are poorly known. By means of star count techniques and field star decontaminated Color Magnitude diagrams, the nature and size of these visual over-densities has been established; and, when possible, new cluster fundamental parameters have been derived. To strengthen our findings, we complement our data-set with JHKs photometry from the 2MASS archive, that we analyze using a suitably defined Q-parameter. Most clusters are projected towards the Carina-Sagittarium spiral arm. Because of that, we detect in the Color Magnitude diagrams of most of the other fields several distinctive sequences produced by young population within the arm. All the clusters are of intermediate or old age. The most interesting cases detected by our study are, perhaps, that of Trumpler 20, which seems to be much older than previously believed, as indicated by its prominent - and double - red clump; and that of Hogg 19, a previously overlooked old open cluster, whose existence in such regions of the Milky Way is puzzling.

  11. Multicolour Optical Photometry of Active Geostationary Satellites

    NASA Astrophysics Data System (ADS)

    Jolley, A.; Wade, G.; Bedard, D.

    Although broadband photometry has been used to infer information about artificial satellites since soon after the launch of Sputnik 1, the development of photometric techniques for non-resolved space object identification or characterisation has been hampered by the large number of variables involved. Many individual studies, and some long ongoing experiments, have used costly metre-class telescopes to obtain data despite other experiments demonstrating that much more flexible and affordable small aperture telescopes may be suitable for the task. In addition, due to the highly time consuming and weather dependent nature of obtaining photometric observations, many studies have suffered from data sets of limited size, or relied upon simulations to support their claims. With this in mind, an experiment was conducted with the aim of determining the utility of small aperture telescopes for conducting broadband photometry of satellites for the purpose of non-resolved space object identification and characterisation. A 14 inch Celestron CG-14 telescope was used to gain multiple night-long, high temporal resolution data sets of six active geostationary satellites. The results of the experiment cast doubt on the efficacy of some of the previous approaches to obtaining and analysing photometric data. It was discovered that geostationary satellite lightcurves can vary to a greater degree than has generally been recognised, and colour ratios vary considerably with changes in the illumination/observation geometry, making it difficult to use colour for satellite discrimination. Evidence was also detected of variations in the spectral energy distribution of sunlight reflected off satellite surface materials, which could have implications for surface material characterisation and techniques that aim to separate satellite body and solar panel contributions to the total observed spectra.

  12. Laser speckle photometry: contactless nondestructive testing technique

    NASA Astrophysics Data System (ADS)

    Cikalova, Ulana; Nicolai, Juergen; Bendjus, Beatrice; Schreiber, Juergen

    2012-10-01

    Laser Speckle Photometry (LSP) is a newly developed contactless, fast and completely optical nondestructive testing method based on the detection and analysis of thermally or mechanically activated characteristic speckle dynamics. The heat propagation or tension process causes locally different degrees of thermal/mechanical expansion, which generates local and time-dependent strain fields, resulting in a local displacement of material surface. During this process, the normal surface slope and absolute height of the microscopic and mesoscopic surface segments, especially at rough sample surfaces, is transformed. These spatiotemporal changes include information about the material structure and conditions. Therefore, the proposed measurement technique includes a pulsed heating source for sample activation, a temperature detection of the sample at the measurement location in a distance from the heading point, a continuous wave laser for sample irradiation and activation of speckle patterns at the measurement point, and in addition, a fast CCD camera for the detection of the speckle movement during heat propagation at the measurement location. Laser Speckle Photometry can be used for evaluating material properties, such as hardness and porosity. The approach is based on the estimation of the "Speckle Thermal Diffusivity" parameter K, that can be determined using the thermal diffusion equation and the modified correlation function from the pixel intensity of the speckle image variations during thermal activation. After testing, the correlation between parameter K and hardness, and porosity respectively, was found. Furthermore, mechanical material stress changes, also at elevated operating temperatures, can be estimated by the presented technique using the calculated parameter K. In this case, the thermal excitation will be partially replaced by mechanical activation, such as the tension process. The technique of LSP and the results of calibration experiments are

  13. The search for red AGN with 2MASS

    NASA Technical Reports Server (NTRS)

    Cutri, R. M.; Nelson, B. O.; Kirkpatrick, J. D.; Huchra, J. P.; Smith, P. S.

    2001-01-01

    We present the results of a simple, highly efficient 2MASS color-based survey that has already discovered 140 previously unknown red AGN and QSOs. These objects are near-infrared-bright and relatively nearby; the media redshift of the sample is z=0.25, and all but two have z<0.7.

  14. 2MASS Extended Source Catalog: Overview and Algorithms

    NASA Technical Reports Server (NTRS)

    Jarrett, T.; Chester, T.; Cutri, R.; Schneider, S.; Skrutskie, M.; Huchra, J.

    1999-01-01

    The 2 Micron All-Sky Survey (2MASS)will observe over one-million galaxies and extended Galactic sources covering the entire sky at wavelenghts between 1 and 2 m. Most of these galaxies, from 70 to 80%, will be newly catalogued objetcs.

  15. Automated surface photometry for the Coma Cluster galaxies: The catalog

    NASA Technical Reports Server (NTRS)

    Doi, M.; Fukugita, M.; Okamura, S.; Tarusawa, K.

    1995-01-01

    A homogeneous photometry catalog is presented for 450 galaxies with B(sub 25.5) less than or equal to 16 mag located in the 9.8 deg x 9.8 deg region centered on the Coma Cluster. The catalog is based on photographic photometry using an automated surface photometry software for data reduction applied to B-band Schmidt plates. The catalog provides accurate positions, isophotal and total magnitudes, major and minor axes, and a few other photometric parameters including rudimentary morphology (early of late type).

  16. THE 2MASS REDSHIFT SURVEY-DESCRIPTION AND DATA RELEASE

    SciTech Connect

    Huchra, John P.; Berlind, Perry; Calkins, Michael; Falco, Emilio; Mink, Jessica D.; Tokarz, Susan; Macri, Lucas M.; Masters, Karen L.; Jarrett, Thomas H.; Crook, Aidan C.; Cutri, Roc; Erdogdu, Pirin; Lahav, Ofer; George, Teddy; Hutcheson, Conrad M.; Mader, Jeff; Martimbeau, Nathalie; Schneider, Stephen; Skrutskie, Michael; Westover, Michael E-mail: karen.masters@port.ac.uk

    2012-04-01

    We present the results of the 2MASS Redshift Survey (2MRS), a ten-year project to map the full three-dimensional distribution of galaxies in the nearby universe. The Two Micron All Sky Survey (2MASS) was completed in 2003 and its final data products, including an extended source catalog (XSC), are available online. The 2MASS XSC contains nearly a million galaxies with K{sub s} {<=} 13.5 mag and is essentially complete and mostly unaffected by interstellar extinction and stellar confusion down to a galactic latitude of |b| = 5 Degree-Sign for bright galaxies. Near-infrared wavelengths are sensitive to the old stellar populations that dominate galaxy masses, making 2MASS an excellent starting point to study the distribution of matter in the nearby universe. We selected a sample of 44,599 2MASS galaxies with K{sub s} {<=} 11.75 mag and |b| {>=} 5 Degree-Sign ({>=}8 Degree-Sign toward the Galactic bulge) as the input catalog for our survey. We obtained spectroscopic observations for 11,000 galaxies and used previously obtained velocities for the remainder of the sample to generate a redshift catalog that is 97.6% complete to well-defined limits and covers 91% of the sky. This provides an unprecedented census of galaxy (baryonic mass) concentrations within 300 Mpc. Earlier versions of our survey have been used in a number of publications that have studied the bulk motion of the Local Group, mapped the density and peculiar velocity fields out to 50 h{sup -1} Mpc, detected galaxy groups, and estimated the values of several cosmological parameters. Additionally, we present morphological types for a nearly complete sub-sample of 20,860 galaxies with K{sub s} {<=} 11.25 mag and |b| {>=} 10 Degree-Sign .

  17. HST Photometry of Uranus 1994-2015

    NASA Astrophysics Data System (ADS)

    Karkoschka, Erich

    2016-10-01

    Images of Uranus by the Hubble Space Telescope (HST) provide a useful tool in studying seasonal and other physical changes on Uranus. HST gives spatial resolution on the disk of Uranus, wide spectral coverage, temporal coverage over more than 20 years, and stable photometric properties. We selected 1368 images in 81 filters of four cameras between 240 and 1130 nm wavelength taken between August 1994 and October 2015.We started with analyzing the photometry of the whole disk of Uranus. We divided the total light of Uranus into the light from "quiet" Uranus and the light from active storms, which can contribute as much as 2.3 % to the total light, although their median contribution is only 0.14 %. The statistical analysis of the light from storms as function of wavelength and time gives clues about their temporal distribution and altitude distribution since different filters probe different altitudes.The photometry of quiet Uranus shows three main variations: a smooth seasonal variation, a small deviation from this on time scales of 1-2 years, and a small variation with phase angle. The latter variation is 0.15 % for each degree of phase angle between 0 and 3 degrees. This may be the first such measurement for Uranus. The deviations from the smooth curve are about 0.2 %, which is significant since most data otherwise fit to the 0.1 % level.The seasonal variation has the same shape at all wavelengths, except that the amplitude differs. The shape is roughly a parabola with a minimum brightness in 2009, two years after the equinox of Uranus. The amplitude is negligible at wavelengths probing high altitudes but goes up to a factor of 2.1 in wavelengths probing the 1-2 bar level. The seasonal variation is a combined effect of physical change in the atmosphere and the geometric change due to variable sub-solar and sub-Earth latitudes. The physical change is further divided into darkening of high southern latitudes and brightening of high northern latitudes. The

  18. Detection of Extrasolar Planets by Transit Photometry

    NASA Technical Reports Server (NTRS)

    Borucki, William; Koch, David; Webster, Larry; Dunham, Edward; Witteborn, Fred; Jenkins, Jon; Caldwell, Douglas; Showen, Robert; DeVincenzi, Donald L. (Technical Monitor)

    2000-01-01

    A knowledge of other planetary systems that includes information on the number, size, mass, and spacing of the planets around a variety of star types is needed to deepen our understanding of planetary system formation and processes that give rise to their final configurations. Recent discoveries show that many planetary systems are quite different from the solar system in that they often possess giant planets in short period orbits. The inferred evolution of these planets and their orbital characteristics imply the absence of Earth-like planets near the habitable zone. Information on the properties of the giant-inner planets is now being obtained by both the Doppler velocity and the transit photometry techniques. The combination of the two techniques provides the mass, size, and density of the planets. For the planet orbiting star HD209458, transit photometry provided the first independent confirmation and measurement of the diameter of an extrasolar planet. The observations indicate a planet 1.27 the diameter of Jupiter with 0.63 of its mass (Charbonneau et al. 1999). The results are in excellent agreement with the theory of planetary atmospheres for a planet of the indicated mass and distance from a solar-like star. The observation of the November 23, 1999 transit of that planet made by the Ames Vulcan photometer at Lick Observatory is presented. In the future, the combination of the two techniques will greatly increase the number of discoveries and the richness of the science yield. Small rocky planets at orbital distances from 0.9 to 1.2 AU are more likely to harbor life than the gas giant planets that are now being discovered. However, new technology is needed to find smaller, Earth-like planets, which are about three hundred times less massive than Jupiter-like planets. The Kepler project is a space craft mission designed to discover hundreds of Earth-size planets in and near the habitable zone around a wide variety of stars. To demonstrate that the

  19. WIYN Open Cluster Study: UBVRI Photometry of NGC 2158

    NASA Astrophysics Data System (ADS)

    Taverne, Luke T.; Steinhauer, Aaron J.; Deliyannis, Constantine P.

    2015-01-01

    We present WIYN 0.9m HDI UBVRI photometry of NGC 2158, a very rich, intermediate-aged, open cluster located near the galactic anti-center. We report derived values for the cluster age, distance, reddening.

  20. CCD Photometry of Seven Asteroids at the Belgrade Astronomical Observatory

    NASA Astrophysics Data System (ADS)

    Benishek, Vladimir

    2008-03-01

    CCD photometry of seven asteroids was performed at the Belgrade Astronomical Observatory from July 2006 to August 2007: 78 Diana, 125 Liberatrix, 702 Alauda, 888 Parysatis, 1095 Tulipa, 1293 Sonja, and 2006 VV2.

  1. Essentials of photometry for clinical electrophysiology of vision.

    PubMed

    McCulloch, Daphne L; Hamilton, Ruth

    2010-08-01

    Electrophysiological testing of the visual system requires familiarity with photometry. This technical note outlines the concepts of photometry with a focus on information relevant to clinical ERG and VEP testing. Topics include photometric quantities, consideration of pupil size, specification of brief extended flash stimuli, and the influence of the spectral composition of visual stimuli. Standard units and terms are explained in the context of the ISCEV standards and guidelines for clinical electrophysiology of vision.

  2. BINARY STAR SYNTHETIC PHOTOMETRY AND DISTANCE DETERMINATION USING BINSYN

    SciTech Connect

    Linnell, Albert P.; DeStefano, Paul; Hubeny, Ivan E-mail: pdestefa@uw.edu

    2013-09-15

    This paper extends synthetic photometry to components of binary star systems. The paper demonstrates accurate recovery of single star photometric properties for four photometric standards, Vega, Sirius, GD153, and HD209458, ranging over the HR diagram, when their model synthetic spectra are placed in fictitious binary systems and subjected to synthetic photometry processing. Techniques for photometric distance determination have been validated for all four photometric standards.

  3. Binary Star Synthetic Photometry and Distance Determination Using BINSYN

    NASA Astrophysics Data System (ADS)

    Linnell, Albert P.; DeStefano, Paul; Hubeny, Ivan

    2013-09-01

    This paper extends synthetic photometry to components of binary star systems. The paper demonstrates accurate recovery of single star photometric properties for four photometric standards, Vega, Sirius, GD153, and HD209458, ranging over the HR diagram, when their model synthetic spectra are placed in fictitious binary systems and subjected to synthetic photometry processing. Techniques for photometric distance determination have been validated for all four photometric standards.

  4. Macular pigment assessment by motion photometry.

    PubMed

    Moreland, J D

    2004-10-15

    A Moreland anomaloscope was modified to measure macular pigment optical density (MPOD) profiles by motion photometry. A grating (spatial frequency 0.38 c deg(-1)), whose alternate bars were filled, respectively, with 460 nm (maximum MP absorption) and 580 nm (zero MP absorption) lights, drifted steadily at 37 degrees s(-1). The subject adjusted the 580 nm radiance to minimise perceived motion (equiluminance between 460 and 580 nm). Five or more settings were made for two foveal fields (0.9 degrees and 2.2 degrees diameter) and 11 extrafoveal annular fields (0.8 degrees -7.5 degrees eccentricity). Twenty subjects made measurements for both eyes: some with replications. MPOD profiles varied in scale (0.18-0.75 for the 0.9 degrees foveal field) and in shape. A mean profile was derived. Foveal data were optimally aligned with annular data in that profile when plotted at 0.71 of the foveal field radius. Factors that limit precision were identified, such as fixation errors foveally and Troxler's effect parafoveally.

  5. BVRI PHOTOMETRY OF 53 UNUSUAL ASTEROIDS

    SciTech Connect

    Ye, Q.-Z.

    2011-02-15

    We present the results of BVRI photometry and classification of 53 unusual asteroids, including 35 near-Earth asteroids (NEAs), 6 high eccentricity/inclination asteroids, and 12 recently identified asteroid-pair candidates. Most of these asteroids were not classified prior to this work. For the few asteroids that have been previously studied, the results are generally in agreement. In addition to observing and classifying these objects, we merge the results from severalphotometric/spectroscopic surveys to create the largest-ever sample with 449 spectrally classified NEAs for statistical analysis. We identify a 'transition point' of the relative number of C/X-like and S-like NEAs at H {approx} 18 {r_reversible} D {approx} 1 km with confidence level at {approx}95% or higher. We find that the C/X-like:S-like ratio for 18 {<=} H < 22 is about twice as high as that of H < 18 (0.33 {+-} 0.04 versus 0.17 {+-} 0.02), virtually supporting the hypothesis that smaller NEAs generally have less weathered surfaces (therefore less reddish appearance) due to younger collision ages.

  6. BVRI photometry of DQ Herculis in 2014

    NASA Astrophysics Data System (ADS)

    Dmitrienko, E. S.; Ibragimov, M. A.; Savanov, I. S.; Satovskii, B. L.; Egamberdiev, Sh. A.; Burkhanov, O. A.

    2015-09-01

    The results of BV RI photometry of the nova DQ Her 1934 performed at the Maidanak Observatory of the Astronomical Institute of the Uzbek Academy of Sciences in October 2014 are presented. The system's brightness, the out-of-eclipse color indices, and the shape of the minima in the BV RI light curves, which are due to eclipses of the white dwarf with its accreting disk-like envelope by the red dwarf, correspond to one of the lowest activity levels observed during the system's deepest relaxation after a nova outburst. The orbital-phase variations of the color indices indicate the presence of a considerably non-uniform brightness distribution for light coming from the disk-like envelope and other gaseous structures of DQ Her, which are observed at orbital phases of 0.85-1.15. The results can be qualitatively interpreted in a picture in which the gas flow structure is formed during mass exchange in an intermediate polar. The behavior found for the color indices could be due, for example, to the visibility in this phase interval of the passage of regions of shocks (tidal shocks, a hot line, and/or a detached shock) through the line of sight.

  7. BVI CCD photometry of 47 Tucanae

    SciTech Connect

    Alcaino, G.; Liller, W.

    1987-08-01

    CCD BVI main-sequence photometry of 47 Tuc is presented, matched to the recent BVI isochrones of VandenBerg and Bell (1985). The main-sequence turnoffs are found to be at V = 17.60 + or - 0.1, B-V = 0.56 + or - 0.02; V-I = 0.68 + or - 0.02, and B-I = 1.24 + or - 0.02. The magnitude difference between the main-sequence turnoff and the horizontal branch is 3.55 + or - 0.15 for all three color indices. A consistent age for 47 Tuc of 17 Gyr and a consistent distance modulus of (m-M)v = 13.2 are obtained for all three indices, and an absolute magnitude of Mv = 0.85 is determined for the horizontal branch stars. The results also favor the adoption of (Fe/H) near -0.5 as the best abundance value for 47 Tuc. 38 references.

  8. The HST Milky Way Stellar Photometry Archive

    NASA Astrophysics Data System (ADS)

    Radburn-Smith, David

    2012-10-01

    The Hubble Legacy Archive has invested a significant effort into automatically generating photometry for point sources in all HST observations regardless of the target. We estimate that this archive contains up to 800,000 Milky Way {MW} stars, distributed across the whole sky, complete to some three magnitudes fainter than SDSS. Approximately half of these stars have color information, which is required for stellar population analysis. This considerable archive is thus in need of collation, analysis, and publication.Here we propose to compile such a catalog for public access and to use it for two science goals: 1} A test of existing MW stellar models, where we will in particular constrain the fainter and more distant stellar populations; and 2} Probe the shape and structure of the MW stellar halo with a deeper star catalog than is currently available. These science cases will be used to fully define the catalog, in particular by assessing the different populations present in the observations, and by assessing the level of noise from contaminants and the completeness of the survey

  9. Recent Advances in Video Meteor Photometry

    NASA Technical Reports Server (NTRS)

    Swift, Wesley R.; Suggs, Robert M.; Meachem, Terry; Cooke, William J.

    2003-01-01

    One of the most common (and obvious) problems with video meteor data involves the saturation of the output signal produced by bright meteors, resulting in the elimination of such meteors from photometric determinations. It is important to realize that a "bright" meteor recorded by intensified meteor camera is not what would be considered "bright" by a visual observer - indeed, many Generation II or III camera systems are saturated by meteors with a visual magnitude of 3, barely even noticeable to the untrained eye. As the relatively small fields of view (approx.30 ) of the camera systems captures at best modest numbers of meteors, even during storm peaks, the loss of meteors brighter than +3 renders the determination of shower population indices from video observations even more difficult. Considerable effort has been devoted by the authors to the study of the meteor camera systems employed during the Marshall Space Flight Center s Leonid ground-based campaigns, and a calibration scheme has been devised which can extend the useful dynamic range of such systems by approximately 4 magnitudes. The calibration setup involves only simple equipment, available to amateur and professional, and it is hoped that use of this technique will make for better meteor photometry, and move video meteor analysis beyond the realm of simple counts.

  10. NEW UBVRI PHOTOMETRY OF 234 M33 STAR CLUSTERS

    SciTech Connect

    Ma Jun

    2013-04-15

    This is the second paper of our series. In this paper, we present UBVRI photometry for 234 star clusters in the field of M33. For most of these star clusters, there is photometry in only two bands in previous studies. The photometry of these star clusters is performed using archival images from the Local Group Galaxies Survey, which covers 0.8 deg{sup 2} along the major axis of M33. Detailed comparisons show that, in general, our photometry is consistent with previous measurements, and in particular that our photometry is in good agreement with that of Zloczewski and Kaluzny. Combined with star cluster photometry in previous studies, we present some results: none of the M33 youngest clusters ({approx}10{sup 7} yr) have masses approaching 10{sup 5} M{sub Sun }, and comparisons with models of simple stellar populations suggest a large range of ages for M33 star clusters and some as old as the Galactic globular clusters.

  11. FIXING THE U-BAND PHOTOMETRY OF TYPE Ia SUPERNOVAE

    SciTech Connect

    Krisciunas, Kevin; Bastola, Deepak; Suntzeff, Nicholas B.; Espinoza, Juan; Gonzalez, David; Gonzalez, Luis; Gonzalez, Sergio; Hsiao, Eric Y.; Morrell, Nidia; Phillips, Mark M.; Hamuy, Mario E-mail: suntzeff@physics.tamu.edu E-mail: hsiao@lco.cl E-mail: mmp@lco.cl

    2013-01-01

    We present previously unpublished photometry of supernovae 2003gs and 2003hv. Using spectroscopically derived corrections to the U-band photometry, we reconcile U-band light curves made from imagery with the Cerro Tololo 0.9 m, 1.3 m, and Las Campanas 1 m telescopes. Previously, such light curves showed a 0.4 mag spread at one month after maximum light. This gives us hope that a set of corrected ultraviolet light curves of nearby objects can contribute to the full utilization of rest-frame U-band data of supernovae at redshift {approx}0.3-0.8. As pointed out recently by Kessler et al. in the context of the Sloan Digital Sky Survey supernova search, if we take the published U-band photometry of nearby Type Ia supernovae at face value, there is a 0.12 mag U-band anomaly in the distance moduli of higher redshift objects. This anomaly led the Sloan survey to eliminate from their analyses all photometry obtained in the rest-frame U-band. The Supernova Legacy Survey eliminated observer frame U-band photometry, which is to say nearby objects observed in the U-band, but they used photometry of high-redshift objects no matter in which band the photons were emitted.

  12. EVIDENCE AGAINST AN EDGE-ON DISK AROUND THE EXTRASOLAR PLANET, 2MASS 1207 b AND A NEW THICK-CLOUD EXPLANATION FOR ITS UNDERLUMINOSITY

    SciTech Connect

    Skemer, Andrew J.; Close, Laird M.; Szucs, Laszlo; Apai, Daniel; Pascucci, Ilaria; Biller, Beth A.

    2011-05-10

    Since the discovery of the first directly imaged, planetary-mass object, 2MASS 1207 b, several works have sought to explain a disparity between its observed temperature and luminosity. Given its known age, distance, and spectral type, 2MASS 1207 b is underluminous by a factor of {approx}10 ({approx}2.5 mag) when compared to standard models of brown-dwarf/giant-planet evolution. In this paper, we study three possible sources of 2MASS 1207 b's underluminosity. First, we investigate Mohanty et al.'s hypothesis that a near edge-on disk, comprising large, gray-extincting grains, might be responsible for 2MASS 1207 b's underluminosity. After radiative transfer modeling, we conclude that the hypothesis is unlikely due to the lack of variability seen in multi-epoch photometry and unnecessary due to the increasing sample of underluminous brown dwarfs/giant exoplanets that cannot be explained by an edge-on disk. Next, we test the analogous possibility that a spherical shell of dust could explain 2MASS 1207 b's underluminosity. Models containing enough dust to create {approx}2.5 mag of extinction, placed at reasonable radii, are ruled out by our new Gemini/T-ReCS 8.7 {mu}m photometric upper limit for 2MASS 1207 b. Finally, we investigate the possibility that 2MASS 1207 b is intrinsically cooler than the commonly used AMES-DUSTY fits to its spectrum, and thus it is not, in fact, underluminous. New, thick-cloud model grids by Madhusudhan et al. fit 2MASS 1207 b's 1-10 {mu}m spectral energy distribution well, but they do not quite fit its near-infrared spectrum. However, we suggest that with some 'tuning', they might be capable of simultaneously reproducing 2MASS 1207 b's spectral shape and luminosity. In this case, the whole class of young, underluminous brown dwarfs/giant exoplanets might be explained by atmospheres that are able to suspend thick, dusty clouds in their photospheres at temperatures lower than field brown dwarfs.

  13. Mesopic luminance assessed with minimum motion photometry.

    PubMed

    Raphael, Sabine; MacLeod, Donald I A

    2011-08-25

    We measured the relative contribution of rods and cones to luminance across a range of photopic, mesopic, and scotopic adaptation levels and at various retinal eccentricities. We isolated the luminance channel by setting motion-based luminance nulls (minimum motion photometry) using annular stimuli. Luminance nulls between differently colored stimuli require equality in a weighted sum of rod and cone excitations. The relative cone weight increases smoothly from the scotopic range, where rods dominate, to photopic levels, where rod influence becomes negligible. The change from rod to cone vision does not occur uniformly over the visual field. The more peripheral the stimulus location, the higher is the light level required for cones to participate strongly. The relative cone contribution can be described by a sigmoid function of intensity, with two parameters that each depend on the eccentricity and spatial frequency of the stimulus. One parameter determines the "meso-mesopic" luminance--the center of the mesopic range, at which rod and cone contributions are balanced. This increases with eccentricity, reflecting an increase in the meso-mesopic luminance from 0.04 scotopic cd/m(2) at 2° eccentricity to 0.44 scotopic cd/m(2) at 18°. The second parameter represents the slope of the log-log threshold-versus-intensity curve (TVI curve) for rod vision. This parameter inversely scales the width of the mesopic range and increases only slightly with eccentricity (from 0.73 at 2° to 0.78 for vision at 18° off-axis).

  14. Multicolor surface photometry of powerful radio galaxies

    SciTech Connect

    Smith, E.P.

    1988-01-01

    CCD images of 72 powerful radio galaxies have been obtained with the KPNO 2.1m, 4m and CTIO 4m telescopes utilizing B, V, and R filters to study the colors and other photometric properties of these large systems. The GASP software package was used for the data reduction and detailed 2-d surface photometry. In addition, image modeling techniques were employed to investigate the contributions to galaxy properties by point-like nuclear sources seen in some of these galaxies. It was found that powerful radio galaxies show a much higher frequency than normal bright ellipticals of having optical morphologies which deviate from elliptical symmetry. Approximately 50% of the sample exhibit non-elliptically symmetric isophotes. These prominent distortions are present at surface brightness levels of {le} 25 V mag/(arc sec){sup 2}. In addition, a large fraction ({approximately}50%) of the remaining radio galaxies without the aforementioned morphological peculiarities have large isophotal twists ({Delta}P.A. {ge} 10{degree}) or ellipticity gradients. Significantly {approximately}50% of the galaxies with strong optical emission lines in their spectra display optically peculiar structures very similar to those found by Toomre and Toomre (1972) in their simulations of interacting disk galaxies. The galaxies with weak emission lines in their spectra are less frequently ({approximately}10%) distorted from elliptical shape. Those that are exhibit features like isophote twists, double nuclei and close companion galaxies embedded in the radio galaxy optical isophotes. The (B-V) colors of many of the powerful radio galaxies with strong emission lines are blue relative to normal giant ellipticals at the same redshift.

  15. HST BVI photometry of Triton and Proteus

    NASA Astrophysics Data System (ADS)

    Pascu, Dan; Storrs, Alex D.; Wells, Eddie N.; Hershey, John L.; Rohde, James R.; Seidelmann, P. Kenneth; Currie, Douglas G.

    2006-12-01

    BVI photometry of Triton and Proteus was derived from HST images taken in 1997. The VEGAMAG photometric technique was used. Triton was found to be brighter by a few percent than observations of the 1970's and 1980's, as expected due to the increasingly greater exposure of the bright south polar region. The leading side was also found to be brighter than the trailing side by 0.09 mag in all filters—50% larger than reported by Franz [Franz, O.G., 1981. Icarus 45, 602-606]. Contrary to our previous results [Pascu, D., et al., 1998. Bull. Am. Astron. Soc. 30, 1101], we found no episodic reddening. Our previous conclusions were based on an inaccurate early version of the Charge Transfer Efficiency (CTE) correction. The present result limits the start of the reddening event reported by Hicks and Buratti [Hicks, M.D., Buratti, B.J., 2004. Icarus 171, 210-218]. Our ( B- V) result of 0.70±0.01 supports the global blueing described by Buratti et al. [Buratti, B.J., Goguen, J.D., Gibson, J., Mosher, J., 1994. Icarus 110, 303-314]. Our observations of July 1997 agree with the Voyager results and are among the bluest colors seen. We found Proteus somewhat brighter than earlier studies, but in good agreement with the recent value given by Karkoschka [Karkoschka, E., 2003. Icarus 162, 400-407]. A leading/trailing brightness asymmetry was detected for Proteus, with the leading side 0.1 mag brighter. The unique differences in action of the endogenic and exogenic processes on Triton and Proteus provides an opportunity to separate the endogenic and exogenic effects on Triton.

  16. Dithering Strategies and Point-Source Photometry

    SciTech Connect

    Samsing, Johan; Kim, Alex G

    2011-02-22

    The accuracy in the photometry of a point source depends on the point-spread function (PSF), detector pixelization, and observing strategy. The PSF and pixel response describe the spatial blurring of the source, the pixel scale describes the spatial sampling of a single exposure, and the observing strategy determines the set of dithered exposures with pointing offsets from which the source flux is inferred. In a wide-field imaging survey, sources of interest are randomly distributed within the field of view and hence are centered randomly within a pixel. A given hardware configuration and observing strategy therefore have a distribution of photometric uncertainty for sources of fixed flux that fall in the field. In this article we explore the ensemble behavior of photometric and position accuracies for different PSFs, pixel scales, and dithering patterns. We find that the average uncertainty in the flux determination depends slightly on dither strategy, whereas the position determination can be strongly dependent on the dithering. For cases with pixels much larger than the PSF, the uncertainty distributions can be non-Gaussian, with rms values that are particularly sensitive to the dither strategy. We also find that for these configurations with large pixels, pointings dithered by a fractional pixel amount do not always give minimal average uncertainties; this is in contrast to image reconstruction for which fractional dithers are optimal. When fractional pixel dithering is favored, a pointing accuracy of better than {approx}0.15 {approx}0.15 pixel width is required to maintain half the advantage over random dithers.

  17. Laser flare-cell photometry: methodology and clinical applications.

    PubMed

    Ladas, John G; Wheeler, Noel C; Morhun, Patrick J; Rimmer, Steven O; Holland, Gary N

    2005-01-01

    Diagnosis and management of intraocular inflammation involves the assessment of cells and protein levels ("flare") in the aqueous humor. These factors are difficult to quantify precisely on clinical examination alone. Laser flare-cell photometry provides an automated technique to quantify these factors objectively, and it has been used in a variety of research and clinical situations to assess anterior segment inflammation. Any new technique requires evaluation to determine accuracy and reproducibility of measured values, and initial applications require critical appraisal to assess the value of the technique. Both in vitro and in vivo studies of laser flare-cell photometry have been performed to determine its validity and utility as a research and clinical tool. This article reviews published studies that describe the technique of laser flare-cell photometry; it provides new in vitro data that supplements information on the capabilities of this technique and factors that influence photometry results, and it reviews representative publications that have used laser flare-cell photometry for study of specific disease entities. This information can help clinicians and researchers to become familiar with the strengths and limitations of laser flare-cell photometry, to identify appropriate future uses for this technique, and to use it and interpret its results appropriately. Laser flare-cell photometry offers an opportunity to improve upon current techniques of inflammation assessment and should not be considered simply an objective surrogate for clinical grading of cells and flare at the slit-lamp biomicroscope. Its research applications and utility for monitoring patients with uveitis have not yet been fully explored.

  18. Age and Structure Parameters of the Remote M31 Globular Cluster B514 Based on HST, 2MASS, GALEX, and BATC Observations

    NASA Astrophysics Data System (ADS)

    Ma, Jun; Wang, Song; Wu, Zhenyu; Fan, Zhou; Zhang, Tianmen; Wu, Jianghua; Zhou, Xu; Jiang, Zhaoji; Chen, Jiansheng

    2012-02-01

    B514 is a remote M31 globular cluster (GC) which is located at a projected distance of Rp ~= 55 kpc. Deep observations with the Advanced Camera for Surveys on the Hubble Space Telescope are used to provide accurate integrated light and star counts of B514. By coupling the analysis of the distribution of the integrated light with star counts, we are able to reliably follow the profile of the cluster out to ~40''. Based on the combined profile, we study in detail its surface brightness distribution in the F606W and F814W filters and determine its structural parameters by fitting a single-mass isotropic King model. The results showed that the surface brightness distribution departs from the best-fit King model for r > 10''. B514 is quite flat in the inner region and has a larger half-light radius than the majority of normal GCs of the same luminosity. It is interesting that, in the MV versus log Rh plane, B514 lies nearly on the threshold for ordinary GCs as defined by Mackey & van den Bergh. In addition, B514 was observed as part of the Beijing-Arizona-Taiwan-Connecticut (BATC) Multicolor Sky Survey, using 13 intermediate-band filters covering a wavelength range of 3000-8500 Å. Based on aperture photometry, we obtain its spectral energy distributions (SEDs) as defined by the 13 BATC filters. We determine the cluster's age and mass by comparing its SEDs (from 2267 to 20000 Å, comprised of photometric data from the near-ultraviolet band of the Galaxy Evolution Explorer, 5 Sloan Digital Sky Survey bands, 13 BATC intermediate-band filters, and Two Micron All Sky Survey near-infrared JHK s filters) with theoretical stellar population synthesis models, resulting in an age of 11.5 ± 3.5 Gyr. This age confirms the previous suggestion that B514 is an old GC in M31. B514 has a mass of 0.96-1.08 × 106 M ⊙ and is a medium-mass GC in M31.

  19. THE PPMXL CATALOG OF POSITIONS AND PROPER MOTIONS ON THE ICRS. COMBINING USNO-B1.0 AND THE TWO MICRON ALL SKY SURVEY (2MASS)

    SciTech Connect

    Roeser, S.; Demleitner, M.; Schilbach, E.

    2010-06-15

    USNO-B1.0 and the Two Micron All Sky Survey (2MASS) are the most widely used all-sky surveys. However, 2MASS has no proper motions at all, and USNO-B1.0 published only relative, not absolute (i.e., on the International Celestial Reference Frame (ICRS), proper motions. We performed a new determination of mean positions and proper motions on the ICRS system by combining USNO-B1.0 and 2MASS astrometry. This catalog is called PPMXL (VO access to the catalog is possible via http://vo.uni-hd.de/ppmxl), and it aims to be completed from the brightest stars down to about V {approx} 20 all sky. PPMXL contains about 900 million objects, some 410 million with 2MASS photometry, and is the largest collection of ICRS proper motions at present. As representative for the ICRS, we chose PPMX. The recently released UCAC3 could not be used because we found plate-dependent distortions in its proper motion system north of -20{sup 0} declination. UCAC3 served as an intermediate system for {delta} {<=} -20{sup 0}. The resulting typical individual mean errors of the proper motions range from 4 mas yr{sup -1} to more than 10 mas yr{sup -1} depending on observational history. The mean errors of positions at epoch 2000.0 are 80-120 mas, if 2MASS astrometry could be used, 150-300 mas else. We also give correction tables to convert USNO-B1.0 observations of, e.g., minor planets to the ICRS system.

  20. Revised Filter Profiles and Zero Points for Broadband Photometry

    NASA Astrophysics Data System (ADS)

    Mann, Andrew W.; von Braun, Kaspar

    2015-02-01

    Estimating accurate bolometric fluxes for stars requires reliable photometry to absolutely flux calibrate the spectra. This is a significant problem for studies of very bright stars, which are generally saturated in modern photometric surveys. Instead we must rely on photometry with less precise calibration. We utilize precisely flux-calibrated spectra to derive improved filter bandpasses and zero points for the most common sources of photometry for bright stars. In total, we test 39 different filters in the General Catalog of Photometric Data as well as those from Tycho-2 and Hipparcos. We show that utilizing inaccurate filter profiles from the literature can create significant color terms resulting in fluxes that deviate by gsim10% from actual values. To remedy this we employ an empirical approach; we iteratively adjust the literature filter profile and zero point, convolve it with catalog spectra, and compare to the corresponding flux from the photometry. We adopt the passband values that produce the best agreement between photometry and spectroscopy and are independent of stellar color. We find that while most zero points change by < 5%, a few systems change by 10-15%. Our final profiles and zero points are similar to recent estimates from the literature. Based on determinations of systematic errors in our selected spectroscopic libraries, we estimate that most of our improved zero points are accurate to 0.5-1%.

  1. Correlating Total Visual Magnitude Estimates and CCD Photometry for Comets

    NASA Astrophysics Data System (ADS)

    Kidger, Mark Richard

    2015-08-01

    A key facet of understanding the activity of comets is coverage of their light curve. For some comets such as 2P/Encke there is good light curve coverage from visual observers extending back over many returns over more than 2 centuries. However, in recent years, CCD photometry by amateur astronomers has become the dominant data source and the number of total visual magnitude estimates has reduced sharply, making comparison of recent and historical photometric data for comets increasingly difficult. The relationship between total visual magnitude estimates - dominated by the emission from the Swan bands of C2 - and CCD aperture photometry - dominated by the dust continuum - has been far from clear.This paper compares CCD aperture photometry and total visual magnitude for several recent well-observed bright comets, including C/2014 Q2 (Lovejoy), C/2012 S1 (ISON) and C/2011 L4 (PanSTARRS) using a consistent and homogeneous database of observations from (mainly) Spanish observers. For comets with a 1/r radial coma profile, good agreement is found between CCD aperture photometry and total visual magnitude estimates for a CCD aperture corresponding to a physical coma diameter of ≈105km.The relationship between the coma radial brightness slope and the equivalent physical aperture for CCD photometry to obtain agreement with total visual magnitude estimates is investigated.

  2. CCD Photometry of bright stars using objective wire mesh

    SciTech Connect

    Kamiński, Krzysztof; Zgórz, Marika; Schwarzenberg-Czerny, Aleksander

    2014-06-01

    Obtaining accurate photometry of bright stars from the ground remains problematic due to the danger of overexposing the target and/or the lack of suitable nearby comparison stars. The century-old method of using objective wire mesh to produce multiple stellar images seems promising for the precise CCD photometry of such stars. Furthermore, our tests on β Cep and its comparison star, differing by 5 mag, are very encouraging. Using a CCD camera and a 20 cm telescope with the objective covered by a plastic wire mesh, in poor weather conditions, we obtained differential photometry with a precision of 4.5 mmag per two minute exposure. Our technique is flexible and may be tuned to cover a range as big as 6-8 mag. We discuss the possibility of installing a wire mesh directly in the filter wheel.

  3. Near-IR Photometry of Nova Del 2013

    NASA Astrophysics Data System (ADS)

    Cass, C. A.; Carlon, L. R.; Corgan, T. D.; Dykhoff, A. D.; Gehrz, D. R.; Shenoy, P. D.

    2013-08-01

    Subjects: Infra-Red, Nova We report Near-IR photometry of Nova Del 2013 taken with the 0.76-m infrared telescope at the University of Minnesota's O'Brien Observatory (Marine on St. Croix, Minnesota, USA). RIJHKLM photometry were obtained on August 21.17 and 23.13 UT using an AsSi bolometer. Vega (alpha Lyrae) was used as the standard star. Our photometry show: August 21.17 UT: R = 5.1 +/- 0.1, I = 4.6 +/- 0.1, J = 4.6 +/- 0.1, H = 4.1 +/- 0.1, K = 3.9 +/- 0.1, L = 2.7 +/- 0.2, M = +2.2 +/- 0.2.

  4. A Study of Dust Cloud Parameters by Vilnius Photometry

    NASA Astrophysics Data System (ADS)

    Smriglio, F.; Dasgupta, A. K.; Boyle, R. P.

    Three-dimensional classification of stars based on their seven-color CCD photometry in the Vilnius system has been succesfully applied to study the small scale structure of interstellar dust clouds. In the present paper the statistical equations of Munch are modified and applied to stars located beyond the galactic absorbing layer. This particular use of Munch's statistics and the properties of CCD photometry in the Vilnius system offer a better possibility of probing the small scale structure of interstellar medium outside of the solar vicinity. This new technique and the first results are discussed.

  5. New Asteroid Models Based on Combined Dense and Sparse Photometry

    NASA Astrophysics Data System (ADS)

    Hanuš, Josef; Durech, J.

    2010-10-01

    For thousands of asteroids we investigated several ten thousands of sparse photometric data from astrometric projects. These data are available on AstDyS server (Asteroids -- Dynamic Site, http://hamilton.dm.unipi.it). We picked 7 astrometric surveys and used their calibrated photometry in lightcurve inversion method for determination of asteroid's convex shapes and rotational states. We present nearly 100 new asteroid models derived from combined dense and sparse data sets, where sparse photometry is taken from AstDyS server and dense lightcurves are from the Uppsala Asteroid Photometric Catalogue (UAPC) and from several individual observers.

  6. SED and Emission Line Properties of Red 2MASS AGN

    NASA Astrophysics Data System (ADS)

    Kuraszkiewicz, Joanna; Wilkes, Belinda J.; Schmidt, Gary; Ghosh, Himel

    2009-09-01

    Radio and far-IR surveys, and modeling of the cosmic X-ray background suggest that a large population of obscured AGN has been missed by traditional, optical surveys. The Two Micron All-Sky Survey (2MASS) has revealed a large population (surface density comparable to that of optically selected AGN with Ks<14.5mag) of mostly nearby (median z=0.25), red, moderately obscured AGN, among which 75% are previously unidentified emission-line AGN, with 85% showing broad emission lines. We present the SED and emission line properties of 44 such red (J-Ks>2) 2MASS AGN observed with Chandra. They lie at z<0.37, span a full range of spectral types (Type 1, intermediate, Type 2),Ks-to-X-ray slopes, and polarization (<13%). Their IR-to-X-ray spectral energy distributions (SEDs) are red in the near-IR/opt/UV showing little or no blue bump. The optical colors are affected by reddening, host galaxy emission, redshift, and in few, highly polarized objects, also by scattered AGN light. The levels of obscuration obtained from optical, X-rays, and far-IR imply N_H

  7. Galileo Photometry of Asteroid 951 Gaspra

    USGS Publications Warehouse

    Helfenstein, P.; Veverka, J.; Thomas, P.C.; Simonelli, D.P.; Lee, P.; Klaasen, K.; Johnson, T.V.; Breneman, H.; Head, J.W.; Murchie, S.; Fanale, F.; Robinson, M.; Clark, B.; Granahan, J.; Garbeil, H.; McEwen, A.S.; Kirk, R.L.; Davies, M.; Neukum, G.; Mottola, S.; Wagner, R.; Belton, M.; Chapman, C.; Pilcher, C.

    1994-01-01

    Galileo images of Gaspra make it possible for the first time to determine a main-belt asteroid's photometric properties accurately by providing surface-resolved coverage over a wide range of incidence and emission angles and by extending the phase angle coverage to phases not observable from Earth. We combine Earth-based telescopic photometry over phase angles 2?? ??? ?? ??? 25?? with Galileo whole-disk and disk-resolved data at 33?? ??? ?? ??? 51?? to derive average global photometric properties in terms of Hapke's photometric model. The microscopic texture and particle phase-function behavior of Gaspra's surface are remarkably like those of other airless rocky bodies such as the Moon. The macroscopic surface roughness parameter, ??̄ = 29??, is slightly larger than that reported for typical lunar materials. The particle single scattering albedo, ??́0 = 0.36 ?? 0.07, is significantly larger than for lunar materials, and the opposition surge amplitude, B0 = 1.63 ?? 0.07, is correspondingly smaller. We determine a visual geometric albedo pv = 0.22 ?? 0.06 for Gaspra, in close agreement with pv = 0.22 ?? 0.03 estimated from Earth-based observations. Gaspra's phase integral is 0.47, and the bolometric Bond albedo is estimated to be 0.12 ?? 0.03. An albedo map derived by correcting Galileo images with our average global photometric function reveals subdued albedo contrasts of ??10% or less over Gaspra's northern hemisphere. Several independent classification algorithms confirm the subtle spectral heterogeneity reported earlier (S. Mottola, M. DiMartino, M. Gonano-Beurer, H. Hoffman, and G. Neukum, 1993, Asteroids, Comets, Meteors, pp. 421-424; M. J. S. Belton et al., 1992, Science 257, 1647-1652). Whole-disk colors (0.41 ??? ?? ??? 0.99 ??m) vary systematically with longitude by about ??5%, but color differences as large as 30% occur locally. Colors vary continuously between end-member materials whose areal distribution correlates with regional topography. Infrared

  8. 2MASS J035523.37+113343.7: A YOUNG, DUSTY, NEARBY, ISOLATED BROWN DWARF RESEMBLING A GIANT EXOPLANET

    SciTech Connect

    Faherty, Jacqueline K.; Rice, Emily L.; Cruz, Kelle L.; Nunez, Alejandro; Mamajek, Eric E. E-mail: jfaherty@amnh.org

    2013-01-01

    We present parallax and proper motion measurements, near-infrared spectra, and Wide-field Infrared Survey Explorer photometry for the low surface gravity L5{gamma} dwarf 2MASS J035523.37+113343.7 (2M0355). We use these data to evaluate photometric, spectral, and kinematic signatures of youth as 2M0355 is the reddest isolated L dwarf yet classified. We confirm its low-gravity spectral morphology and find a strong resemblance to the sharp triangular shaped H-band spectrum of the {approx}10 Myr planetary-mass object 2M1207b. We find that 2M0355 is underluminous compared to a normal field L5 dwarf in the optical and Mauna Kea Observatory J, H, and K bands and transitions to being overluminous from 3 to 12 {mu}m, indicating that enhanced photospheric dust shifts flux to longer wavelengths for young, low-gravity objects, creating a red spectral energy distribution. Investigating the near-infrared color-magnitude diagram for brown dwarfs confirms that 2M0355 is redder and underluminous compared to the known brown dwarf population, similar to the peculiarities of directly imaged exoplanets 2M1207b and HR8799bcd. We calculate UVW space velocities and find that the motion of 2M0355 is consistent with young disk objects (<2-3 Gyr) and it shows a high likelihood of membership in the AB Doradus association.

  9. 2MASS J035523.37+113343.7: A Young, Dusty, Nearby, Isolated Brown Dwarf Resembling a Giant Exoplanet

    NASA Astrophysics Data System (ADS)

    Faherty, Jacqueline K.; Rice, Emily L.; Cruz, Kelle L.; Mamajek, Eric E.; Núñez, Alejandro

    2013-01-01

    We present parallax and proper motion measurements, near-infrared spectra, and Wide-field Infrared Survey Explorer photometry for the low surface gravity L5γ dwarf 2MASS J035523.37+113343.7 (2M0355). We use these data to evaluate photometric, spectral, and kinematic signatures of youth as 2M0355 is the reddest isolated L dwarf yet classified. We confirm its low-gravity spectral morphology and find a strong resemblance to the sharp triangular shaped H-band spectrum of the ~10 Myr planetary-mass object 2M1207b. We find that 2M0355 is underluminous compared to a normal field L5 dwarf in the optical and Mauna Kea Observatory J, H, and K bands and transitions to being overluminous from 3 to 12 μm, indicating that enhanced photospheric dust shifts flux to longer wavelengths for young, low-gravity objects, creating a red spectral energy distribution. Investigating the near-infrared color-magnitude diagram for brown dwarfs confirms that 2M0355 is redder and underluminous compared to the known brown dwarf population, similar to the peculiarities of directly imaged exoplanets 2M1207b and HR8799bcd. We calculate UVW space velocities and find that the motion of 2M0355 is consistent with young disk objects (<2-3 Gyr) and it shows a high likelihood of membership in the AB Doradus association.

  10. Infrared space observatory photometry of circumstellar dust in Vega-type systems

    NASA Technical Reports Server (NTRS)

    Fajardo-Acosta, S. B.; Stencel, R. E.; Backman, D. E.; Thakur, N.

    1998-01-01

    The ISOPHOT (Infrared Space Observatory Photometry) instrument onboard the Infrared Space Observatory (ISO) was used to obtain 3.6-90 micron photometry of Vega-type systems. Photometric data were calibrated with the ISOPHOT fine calibration source 1 (FCS1). Linear regression was used to derive transformations to make comparisons to ground-based and IRAS photometry systems possible. These transformations were applied to the photometry of 14 main-sequence stars. Details of these results are reported on.

  11. Extinctions and Distances to Dark Clouds from 2MASS, MegaCam and IPHAS Surveys: LDN 1525 in the Direction of the Aur OB1 Association

    NASA Astrophysics Data System (ADS)

    Straižys, V.; Drew, J. E.; Laugalys, V.

    The possibility of applying photometry from the 2MASS J, H, Ks, MegaCam u, g and IPHAS r, i, Hα surveys for determining the distance to the dark cloud LDN 1525 (TGU 1192) in the direction of the Aur OB1 association is investigated using the red clump giants. The main dust cloud, probably related to the emission nebulae Sh 2-232, Sh 2-233, Sh 2-235, the molecular cloud and the association Aur OB2, is found to be located at a distance of 1.3 kpc from the Sun. The nebula Sh 2-231 can be an object of the Perseus arm. The maximum extinction AV found in the cloud is close to 6 mag.

  12. NIR photometry of the flaring Blazar PKS2320-035

    NASA Astrophysics Data System (ADS)

    Carrasco, L.; Recillas, E.; Porras, A.; Chavushyan, V.; Carraminana, A.

    2015-12-01

    Following the report by L. Pacciani (ATEL#8323) on the flaring state of the FSRQ PKS2320-035 a high redshift QSO (z=1.411) also known as BZQJ 2323-0317, associated with the Gamma-ray Source 2GGLJ2323.6-0316, We carried out NIR photometry of this object on December 5th,2015 (MJD2457361.662).

  13. Iontophoresis and Flame Photometry: A Hybrid Interdisciplinary Experiment

    ERIC Educational Resources Information Center

    Sharp, Duncan; Cottam, Linzi; Bradley, Sarah; Brannigan, Jeanie; Davis, James

    2010-01-01

    The combination of reverse iontophoresis and flame photometry provides an engaging analytical experiment that gives first-year undergraduate students a flavor of modern drug delivery and analyte extraction techniques while reinforcing core analytical concepts. The experiment provides a highly visual demonstration of the iontophoresis technique and…

  14. Photometry requested for three "Vestoid" Near-Earth Objects

    NASA Astrophysics Data System (ADS)

    Templeton, Matthew R.

    2011-01-01

    Dr. Michael David Hicks (Jet Propulsion Laboratory) contacted the AAVSO requesting precision photometry of three solar system objects in support of NASA's DAWN mission to Vesta. These "Vestoids" are near-Earth objects with reflectance spectra similar to Vesta itself, suggesting they may be fragments of that larger body. Broad-band photometry may help constrain object sizes and compositions. The objects are 1981 Midas (1973 EA), 4688 (1980 WF), and 137052 (1998 VO33). Hicks and collaborators are hoping to obtain photometry at the 0.1-magnitude level or better of all three objects during some or all of the first four months of 2011. All are fainter than 16th magnitude throughout their apparitions during this time frame. Multiple exposures will likely be required to reach the required signal to noise for most observers, and 4688 (1980 WF) will likely be beyond the capabilities of most telescopes by early March 2011. The Alert Notice includes ephemerides computed from known orbital parameters computed in intervals of five days beginning 2011 January 07 (JD 2455568). Magnitudes in the tables are V. Observations are requested using Rc filter if possible; V filter observations are also acceptable. We note that since these are solar system objects, they are not included in the AAVSO International Database. Observers are asked to communicate their photometry directly to the PI, and to email Elizabeth Waagen at AAVSO Headquarters so we know that you have participated.

  15. Follow-up photometry of iPTF16geu

    NASA Astrophysics Data System (ADS)

    Lee, C.-H.

    2016-10-01

    We report follow-up photometry of the strongly lensed SNIa iPTF16geu (ATel #9603, #9626). We observed iPTF16geu on 2016/10/17 with the 2.5-m Isaac Newton Telescope (INT) + WFC at La Palma, under ~0.9" seeing condition.

  16. Characterization of Transiting Exoplanets by Way of Differential Photometry

    ERIC Educational Resources Information Center

    Cowley, Michael; Hughes, Stephen

    2014-01-01

    This paper describes a simple activity for plotting and characterizing the light curve from an exoplanet transit event by way of differential photometry analysis. Using free digital imaging software, participants analyse a series of telescope images with the goal of calculating various exoplanet parameters, including size, orbital radius and…

  17. Photometry of Faint and Wide Doubles in Vulpecula

    NASA Astrophysics Data System (ADS)

    Knapp, Wilfried; Thuemen, Chris

    2016-04-01

    Images of several double stars in Vulpecula published on the "Double Star Imaging Project" Yahoo Group page suggest magnitude issues compared with the corresponding WDS catalog data per April 2015. Taking additional images with V-filter enabled photometry for these pairs, providing confirming results.

  18. Photometry of Faint and Wide Doubles in Sagitta

    NASA Astrophysics Data System (ADS)

    Knapp, Wilfried; Thuemen, Chris

    2016-02-01

    Images of several double stars in Sagitta published on the "Double Star Imaging Project" Yahoo Group page suggest magnitude issues compared with the corresponding WDS catalog data per April 2015. Taking additional images with V-filter enabled photometry for these pairs, provided confirming results.

  19. Photometry and Measurement of Faint and Wide Doubles in Eridanus

    NASA Astrophysics Data System (ADS)

    Knapp, Wilfried; Thuemen, Chris

    2015-07-01

    Images of several double stars in Eridanus published on the "Double Star Imaging Project" Yahoo Group page suggest magnitude issues compared with the corresponding WDS catalog data per 2014.12. Taking additional images with V-filter enabled photometry for these pairs with confirming results.

  20. JCMT COADD: UKT14 continuum and photometry data reduction

    NASA Astrophysics Data System (ADS)

    Hughes, David; Oliveira, Firmin J.; Tilanus, Remo P. J.; Jenness, Tim

    2014-11-01

    COADD was used to reduce photometry and continuum data from the UKT14 instrument on the James Clerk Maxwell Telescope in the 1990s. The software can co-add multiple observations and perform sigma clipping and Kolmogorov-Smirnov statistical analysis. Additional information on the software is available in the JCMT Spring 1993 newsletter (large PDF).

  1. A Galactic Plane relative extinction map from 2MASS

    NASA Astrophysics Data System (ADS)

    Froebrich, D.; Ray, T. P.; Murphy, G. C.; Scholz, A.

    2005-03-01

    We present three 14 400 square degree relative extinction maps of the Galactic Plane (|b| < 20°) obtained from 2MASS using accumulative star counts (Wolf diagrams). This method is independent of the colour of the stars and the variation of extinction with wavelength. Stars were counted in 3.5 × 3.5 boxes, every 20.1° × 1° surrounding fields were chosen for reference, hence the maps represent local extinction enhancements and ignore any contribution from the ISM or very large clouds. Data reduction was performed on a Beowulf-type cluster (in approximately 120 hours). Such a cluster is ideal for this type of work as areas of the sky can be independently processed in parallel. We studied how extinction depends on wavelength in all of the high extinction regions detected and within selected dark clouds. On average a power law opacity index (β) of 1.0 to 1.8 in the NIR was deduced. The index however differed significantly from region to region and even within individual dark clouds. That said, generally it was found to be constant, or to increase, with wavelength within a particular region.

  2. VizieR Online Data Catalog: JKH photometry in LDN 1688 (Wilking+, 2008)

    NASA Astrophysics Data System (ADS)

    Wilking, B. A.; Gagne, M.; Allen, L. E.

    2008-11-01

    A review of star formation in the Rho Ophiuchi molecular complex is presented, with particular emphasis on studies of the main cloud, L1688, since 1991. Recent photometric and parallax measurements of stars in the Upper Scorpius subgroup of the Sco-Cen OB association suggest a distance for the cloud between 120 and 140 parsecs. Star formation is ongoing in the dense cores of L1688 with a median age for young stellar objects of 0.3Myr. The surface population appears to have a median age of 2-5Myr and merges with low mass stars in the Upper Scorpius subgroup. Making use of the most recent X-ray and infrared photometric surveys and spectroscopic surveys of L1688, we compile a list of over 300 association members with counterparts in the 2MASS catalog. Membership criteria, such as lithium absorption, X-ray emission, and infrared excess, cover the full range of evolutionary states for young stellar objects. Spectral energy distributions are classified for many association members using infrared photometry obtained from the Spitzer Space Telescope. (2 data files).

  3. VizieR Online Data Catalog: Gaia photometry for white dwarfs (Carrasco+, 2014)

    NASA Astrophysics Data System (ADS)

    Carrasco, J. M.; Catalan, S.; Jordi, C.; Tremblay, P.-E.; Napiwotzki, R.; Luri, X.; Robin, A. C.; Kowalski, P. M.

    2014-03-01

    The Gaia space mission, through its 5-6 years survey of the whole sky up to magnitude V=20-25, will drastically increase the sample of known white dwarfs allowing to address new science questions. In this paper we provide a characterisation of Gaia photometry for the case of white dwarfs to better prepare for the analysis of the scientific output of the mission including relationships among colours involving Gaia magnitudes (white light G, blue GBP, red GRP and GRVS passbands) and colours from other commonly used photometric systems (Johnson-Cousins, SDSS and 2MASS). We also present numbers of white dwarfs predicted by the Gaia Universe Model Snapshot and compare them with an alternative simulation calibrated with the local white dwarfs sample. In these online tables we provide the values used to fit the relationships in the paper, especially useful for those cases where the deviation from the established relationships is large. The most recent Gaia transmission curves and three different compositions for white dwarfs were considered here (pure hydrogen, pure helium and mixed composition with H/He=0.1). (3 data files).

  4. VizieR Online Data Catalog: Infrared photometry of all known members in Taurus (Esplin+, 2014)

    NASA Astrophysics Data System (ADS)

    Esplin, T. L.; Luhman, K. L.; Mamajek, E. E.

    2016-08-01

    =100 for all targets except 2MASS J04221376+1525298, which was observed with the short cross-dispersed (SXD) mode (R=800). Our classifications are presented in Table6. The 34 remaining viable candidates that have not been observed with spectroscopy are presented in Table7. (6 data files).

  5. VizieR Online Data Catalog: Infrared photometry of all known members in Taurus (Esplin+, 2014)

    NASA Astrophysics Data System (ADS)

    Esplin, T. L.; Luhman, K. L.; Mamajek, E. E.

    2016-08-01

    =100 for all targets except 2MASS J04221376+1525298, which was observed with the short

  6. CIRCUMSTELLAR ENVIRONMENT AND EFFECTIVE TEMPERATURE OF THE YOUNG SUBSTELLAR ECLIPSING BINARY 2MASS J05352184-0546085

    SciTech Connect

    Mohanty, Subhanjoy; Stassun, Keivan G.; Mathieu, Robert D.

    2009-05-20

    We present new Spitzer IRAC/PU/MIPS photometry from 3.6 to 24 {mu}m, and new Gemini GMOS photometry at 0.48 {mu}m, of the young brown dwarf eclipsing binary 2MASS J05352184-0546085, located in the Orion Nebula Cluster. No excess disk emission is detected. The measured fluxes at {lambda} {<=} 8 {mu}m are within 1{sigma} ({approx}<0.1 mJy) of a bare photosphere, and the 3{sigma} upper limit at 16 {mu}m is a mere 0.04 mJy above the bare photospheric level. Together with the known properties of the system, this implies the absence of optically thick disks around the individual components. It also implies that if any circumbinary disk is present, it must either be optically thin and extremely tenuous (10{sup -10} M {sub sun}) if it extends in to within {approx}0.1 AU of the binary (the approximate tidal truncation radius), or it must be optically thick with a large inner hole, >0.6-10 AU in radius depending on degree of flaring. The consequence in all cases is that disk accretion is likely to be negligible or absent. This supports the recent proposal that the strong H{alpha} emission in the primary (more massive) brown dwarf results from chromospheric activity, and thereby bolsters the hypothesis that the surprising T {sub eff} inversion observed between the components is due to strong magnetic fields on the primary. Our data also set constraints on the T {sub eff} of the components independent of spectral type, and thereby on models of the aforementioned magnetic field effects. We discuss the consequences for the derived fundamental properties of young brown dwarfs and very low mass stars in general. Specifically, if very active isolated young brown dwarfs and very low mass stars suffer the same activity/field related effects as the 2M0535-05 primary, the low-mass stellar/substellar initial mass function currently derived from standard evolutionary tracks may be substantially in error.

  7. Local systematic differences in proper motions derived from 2MASS positions

    NASA Astrophysics Data System (ADS)

    Bustos Fierro, I. H.; Calderón, J. H.

    2016-04-01

    We want to draw attention to local systematic differences that appear in the proper motions derived from 2MASS positions when they are compared with other astrometric catalogs such as UCAC4, SPM4 and USNO-B1. It is shown that 2MASS effectively causes these systematic effects in the proper motions of PPMXL and URAT1. Also it is shown that using 2MASS positions rectified with respect to UCAC4 the systematic pattern of the proper motions of URAT1 is eliminated. Therefore, we propose the use of rectified 2MASS positions in order to derive proper motions free from 2MASS systematics.

  8. Copernicus spectra and infrared photometry of 42 Orionis

    NASA Technical Reports Server (NTRS)

    Johnson, H. M.; Snow, T. P., Jr.; Gehrz, R. D.; Hackwell, J. A.

    1977-01-01

    The Orion sword star 42 Ori is embedded in a nebula north of and separated from the Orion nebula. The B1 V star is probably normal. Other members of the multiple remain poorly defined, and the nebula may exhibit some peculiarities that may depend on them. Copernicus ultraviolet spectra of the star are described here, especially in the form of tables of wavelength identifications. The properties of the interstellar material in the line of sight are also discussed. Infrared photometry is presented which suggests that the ratio of total to selective extinction ranges from 3 to 3.5 for the interstellar matter in the direction of 42 Ori. The IR photometry provides no evidence for companion stellar or circumstellar components.

  9. Absolute stellar photometry on moderate-resolution FPA images

    USGS Publications Warehouse

    Stone, T.C.

    2009-01-01

    An extensive database of star (and Moon) images has been collected by the ground-based RObotic Lunar Observatory (ROLO) as part of the US Geological Survey program for lunar calibration. The stellar data are used to derive nightly atmospheric corrections for the observations from extinction measurements, and absolute calibration of the ROLO sensors is based on observations of Vega and published reference flux and spectrum data. The ROLO telescopes were designed for imaging the Moon at moderate resolution, thus imposing some limitations for the stellar photometry. Attaining accurate stellar photometry with the ROLO image data has required development of specialized processing techniques. A key consideration is consistency in discriminating the star core signal from the off-axis point spread function. The analysis and processing methods applied to the ROLO stellar image database are described. ?? 2009 BIPM and IOP Publishing Ltd.

  10. An Aperture Photometry Pipeline for K2 Data

    NASA Astrophysics Data System (ADS)

    Buzasi, Derek L.; Carboneau, Lindsey; Lezcano, Andy; Vydra, Ekaterina

    2016-01-01

    As part of an ongoing research program with undergraduate students at Florida Gulf Coast University, we have constructed an aperture photometry pipeline for K2 data. The pipeline performs dynamic automated aperture mask definition for all targets in the K2 fields, followed by aperture photometry and detrending. Our pipeline is currently used to support a number of projects, including studies of stellar rotation and activity, red giant asteroseismology, gyrochronology, and exoplanet searches. In addition, output is used to support an undergraduate class on exoplanets aimed at a student audience of both majors and non-majors. The pipeline is designed for both batch and single-target use, and is easily extensible to data from other missions, and pipeline output is available to the community. This paper will describe our pipeline and its capabilities and illustrate the quality of the results, drawing on all of the applications for which it is currently used.

  11. One Percent Strömvil Photometry in M 67

    NASA Astrophysics Data System (ADS)

    Philip, A. G. D.; Boyle, R. P.; Janusz, R.

    2005-05-01

    The Vatican Advanced Technology Telescope on Mt. Graham is being used in a program of CCD photometry of open and globular clusters. We are using the Ströomvil System (Straižys et al. 1996), a combination of the Strömgren and Vilnius Systems. This system allows stars to be classified as to temperature, surface gravity, metallicity and reddening from the photometric measures alone. However, to make accurate estimates of the stellar parameters the photometry should be accurate to 1 or 1.5 percent. In our initial runs on the VATT we did not achieve this accuracy. The problem turned out to be scattered light in the telescope and this has now been reduced so we can do accurate photometry. Boyle has written a routine in IRAF which allows us to correct the flats for any differences. We take rotated frames and also frames which are offset in position by one third of a frame, east-west and north-south. Measures of the offset stars give us the corrections that need to be made to the flat. Robert Janusz has written a program, the CommandLog, which allows us to paste IRAF commands in the correct order to reduce measures made on a given observing run. There is an automatic version where one can test various parameters and get a set of solutions. Now we have a set of Strömvil frames in the open cluster, M 67 and we compare our color-magnitude diagram with those of BATC (Fan et al. 1996) and Vilnius (Boyle et al. 1998). A preliminary report of the M 67 photometry will be found in Laugalys et al. (2004). Here we report on a selected set of stars in the M 67 frames, those with errors 1 percent or less.

  12. Theory of wide-angle photometry from standard stars

    NASA Technical Reports Server (NTRS)

    Usher, Peter D.

    1989-01-01

    Wide angle celestial structures, such as bright comet tails and nearby galaxies and clusters of galaxies, rely on photographic methods for quantified morphology and photometry, primarily because electronic devices with comparable resolution and sky coverage are beyond current technological capability. The problem of the photometry of extended structures and of how this problem may be overcome through calibration by photometric standard stars is examined. The perfect properties of the ideal field of view are stated in the guise of a radiometric paraxial approximation, in the hope that fields of view of actual telescopes will conform. Fundamental radiometric concepts are worked through before the issue of atmospheric attenuation is addressed. The independence of observed atmospheric extinction and surface brightness leads off the quest for formal solutions to the problem of surface photometry. Methods and problems of solution are discussed. The spectre is confronted in the spirit of standard stars and shown to be chimerical in that light, provided certain rituals are adopted. After a brief discussion of Baker-Sampson polynomials and the vexing issue of saturation, a pursuit is made of actual numbers to be expected in real cases. While the numbers crunched are gathered ex nihilo, they demonstrate the feasibility of Newton's method in the solution of this overdetermined, nonlinear, least square, multiparametric, photometric problem.

  13. Multi-channel fiber photometry for population neuronal activity recording.

    PubMed

    Guo, Qingchun; Zhou, Jingfeng; Feng, Qiru; Lin, Rui; Gong, Hui; Luo, Qingming; Zeng, Shaoqun; Luo, Minmin; Fu, Ling

    2015-10-01

    Fiber photometry has become increasingly popular among neuroscientists as a convenient tool for the recording of genetically defined neuronal population in behaving animals. Here, we report the development of the multi-channel fiber photometry system to simultaneously monitor neural activities in several brain areas of an animal or in different animals. In this system, a galvano-mirror modulates and cyclically couples the excitation light to individual multimode optical fiber bundles. A single photodetector collects excited light and the configuration of fiber bundle assembly and the scanner determines the total channel number. We demonstrated that the system exhibited negligible crosstalk between channels and optical signals could be sampled simultaneously with a sample rate of at least 100 Hz for each channel, which is sufficient for recording calcium signals. Using this system, we successfully recorded GCaMP6 fluorescent signals from the bilateral barrel cortices of a head-restrained mouse in a dual-channel mode, and the orbitofrontal cortices of multiple freely moving mice in a triple-channel mode. The multi-channel fiber photometry system would be a valuable tool for simultaneous recordings of population activities in different brain areas of a given animal and different interacting individuals.

  14. High speed low noise multiplexed three color absorbance photometry.

    PubMed

    Dadesh, Khaled M; Kurup, G K; Basu, Amar S

    2011-01-01

    Multispectral photometry is often required to distinguish samples in flow injection analysis and flow cytometry; however, the cost of multiple light detectors, filters, and optical paths contribute to the high cost of multicolor and spectral detection systems. This paper describes frequency division multiplexing (FDM), a simple approach for performing multi-wavelength absorbance photometry with a single light detector and a single interrogation window. In previous efforts, modulation frequencies were <10 KHz, resulting in a detector bandwidth of <20 Hz. This paper presents a high frequency FDM circuit which can increase the oscillation frequencies to several 100 KHz, improving the detection bandwidth by a factor of 10 while still maintaining low cost. Light from 3 different LED sources are encoded into unique frequency channels, passed through the detection cell, and later demodulated using phase-sensitive electronics. Electronic multiplexing couples all light sources into a single optical train without spectral filters. Theory and high frequency considerations are demonstrated. Simultaneous three color absorbance detection is demonstrated in solutions and in flowing droplet microreactors. This technique can potentially reduce the cost of multicolor photometry by replacing expensive optical components with low-cost electronics.

  15. Theory of wide-angle photometry from standard stars

    NASA Astrophysics Data System (ADS)

    Usher, Peter D.

    1989-10-01

    Wide angle celestial structures, such as bright comet tails and nearby galaxies and clusters of galaxies, rely on photographic methods for quantified morphology and photometry, primarily because electronic devices with comparable resolution and sky coverage are beyond current technological capability. The problem of the photometry of extended structures and of how this problem may be overcome through calibration by photometric standard stars is examined. The perfect properties of the ideal field of view are stated in the guise of a radiometric paraxial approximation, in the hope that fields of view of actual telescopes will conform. Fundamental radiometric concepts are worked through before the issue of atmospheric attenuation is addressed. The independence of observed atmospheric extinction and surface brightness leads off the quest for formal solutions to the problem of surface photometry. Methods and problems of solution are discussed. The spectre is confronted in the spirit of standard stars and shown to be chimerical in that light, provided certain rituals are adopted. After a brief discussion of Baker-Sampson polynomials and the vexing issue of saturation, a pursuit is made of actual numbers to be expected in real cases. While the numbers crunched are gathered ex nihilo, they demonstrate the feasibility of Newton's method in the solution of this overdetermined, nonlinear, least square, multiparametric, photometric problem.

  16. Improved Asteroid Astrometry and Photometry with Trail Fitting

    NASA Astrophysics Data System (ADS)

    Vereš, Peter; Jedicke, Robert; Denneau, Larry; Wainscoat, Richard; Holman, Matthew J.; Lin, Hsing-Wen

    2012-11-01

    Asteroid detections in astronomical images may appear as trails due to a combination of their apparent rate of motion and exposure duration. Nearby asteroids in particular typically have high apparent rates of motion and acceleration. Their recovery, especially on their discovery apparition, depends upon obtaining good astrometry from the trailed detections. We present an analytic function describing a trailed detection under the assumption of a Gaussian point spread function (PSF) and constant rate of motion. We have fit the function to both synthetic and real trailed asteroid detections from the Pan-STARRS1 survey telescope to obtain accurate astrometry and photometry. For short trails our trailing function yields the same astrometric and photometry accuracy as a functionally simpler two-dimensional Gaussian but the latter underestimates the length of the trail—a parameter that can be important for measuring the object's rate of motion and assessing its cometary activity. For trails longer than about 10 pixels (~3× PSF) our trail fitting provides ~3× better astrometric accuracy and up to two magnitudes improvement in the photometry. The trail fitting algorithm can be implemented at the source detection level for all detections to provide trail length and position angle that can be used to reduce the false tracklet rate.

  17. Night sky photometry with amateur-grade digital cameras

    NASA Astrophysics Data System (ADS)

    Mrozek, Tomasz; Gronkiewicz, Dominik; Kolomanski, Sylwester; Steslicki, Marek

    2015-08-01

    Measurements of night sky brightness can give us valuable information on light pollution. The more the measurements we have the better is our knowledge on the spatial distribution of the pollution on local and global scale.High accuracy professional photometry of night sky can be performed with dedicated instruments. The main drawbacks of this method are high price and low mobility. This limits an amount of observers and therefore amount of photometric data that can be collected. In order to overcome the problem of limited amount of data we can involve amateur astronomers in photometry of night sky. However, to achieve this goal we need a method that utilizes equipment which is usually used by amateur astronomers, e.g digital cameras.We propose a method that enables good accuracy photometry of night sky with a use of digital compact or DSLR cameras. In the method reduction of observations and standarization to Johnson UBV system are performed. We tested several cameras and compared results to Sky Quality Meter (SQM) measurements. The overall consistency for results is within 0.2 mag.

  18. M2K Planet Search: Spectroscopic Screening and Transit Photometry

    NASA Astrophysics Data System (ADS)

    Mann, Andrew; Gaidos, E.; Fischer, D.; Lepine, S.

    2010-10-01

    The M2K project is a search for planets orbiting nearby early M and late K dwarf drawn from the SUPERBLINK catalog. M and K dwarfs are highly attractive targets for finding low-mass and habitable planets because (1) close-in planets are more likely to orbit within their habitable zone, (2) planets orbiting them induce a larger Doppler signal and have deeper transits than similar planets around F, G, and early K type stars, (3) planet formation models predict they hold an abundance of super-Earth sized planets, and (4) they represent the vast majority of the stars close enough for direct imaging techniques. In spite of this, only 10% of late K and early M dwarfs are being monitored by current Doppler surveys. As part of the M2K project we have obtained low-resolution spectra for more than 2000 of our sample of 10,000 M and K dwarfs. We vet our sample by screening these stars for high metallicity and low chromospheric activity. We search for transits on targets showing high RMS Doppler signal and photometry candidates provided by SuperWASP project. By using "snapshot” photometry have been able to achieve sub-millimag photometry on numerous transit targets in the same night. With further follow-up observations we will be able to detect planets smaller than 10 Earth masses.

  19. Identification of red supergiants in nearby galaxies with mid-IR photometry

    NASA Astrophysics Data System (ADS)

    Britavskiy, N. E.; Bonanos, A. Z.; Mehner, A.; García-Álvarez, D.; Prieto, J. L.; Morrell, N. I.

    2014-02-01

    Context. The role of episodic mass loss in massive-star evolution is one of the most important open questions of current stellar evolution theory. Episodic mass loss produces dust and therefore causes evolved massive stars to be very luminous in the mid-infrared and dim at optical wavelengths. Aims: We aim to increase the number of investigated luminous mid-IR sources to shed light on the late stages of these objects. To achieve this we employed mid-IR selection criteria to identity dusty evolved massive stars in two nearby galaxies. Methods: The method is based on mid-IR colors, using 3.6 μm and 4.5 μm photometry from archival Spitzer Space Telescope images of nearby galaxies and J-band photometry from 2MASS. We applied our criteria to two nearby star-forming dwarf irregular galaxies, Sextans A and IC 1613, selecting eight targets, which we followed-up with spectroscopy. Results: Our spectral classification and analysis yielded the discovery of two M-type supergiants in IC 1613, three K-type supergiants and one candidate F-type giant in Sextans A, and two foreground M giants. We show that the proposed criteria provide an independent way for identifying dusty evolved massive stars that can be extended to all nearby galaxies with available Spitzer/IRAC images at 3.6 μm and 4.5 μm. Based on observations made with the Gran Telescopio Canarias (GTC), installed in the Spanish Observatorio de El Roque de Los Muchachos of the Instituto de Astrofísica de Canarias, on the island of La Palma, and the 2.5 m du Pont telescope in operation at Las Campanas Observatory, Chile.Spectra are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/562/A75

  20. Improving Kepler Pipeline Sensitivity with Pixel Response Function Photometry.

    NASA Astrophysics Data System (ADS)

    Morris, Robert L.; Bryson, Steve; Jenkins, Jon Michael; Smith, Jeffrey C

    2014-06-01

    We present the results of our investigation into the feasibility and expected benefits of implementing PRF-fitting photometry in the Kepler Science Processing Pipeline. The Kepler Pixel Response Function (PRF) describes the expected system response to a point source at infinity and includes the effects of the optical point spread function, the CCD detector responsivity function, and spacecraft pointing jitter. Planet detection in the Kepler pipeline is currently based on simple aperture photometry (SAP), which is most effective when applied to uncrowded bright stars. Its effectiveness diminishes rapidly as target brightness decreases relative to the effects of noise sources such as detector electronics, background stars, and image motion. In contrast, PRF photometry is based on fitting an explicit model of image formation to the data and naturally accounts for image motion and contributions of background stars. The key to obtaining high-quality photometry from PRF fitting is a high-quality model of the system's PRF, while the key to efficiently processing the large number of Kepler targets is an accurate catalog and accurate mapping of celestial coordinates onto the focal plane. If the CCD coordinates of stellar centroids are known a priori then the problem of PRF fitting becomes linear. A model of the Kepler PRF was constructed at the time of spacecraft commissioning by fitting piecewise polynomial surfaces to data from dithered full frame images. While this model accurately captured the initial state of the system, the PRF has evolved dynamically since then and has been seen to deviate significantly from the initial (static) model. We construct a dynamic PRF model which is then used to recover photometry for all targets of interest. Both simulation tests and results from Kepler flight data demonstrate the effectiveness of our approach. Kepler was selected as the 10th mission of the Discovery Program. Funding for this mission is provided by NASA’s Science

  1. VizieR Online Data Catalog: 3D reddening map for stars from 2MASS phot. (Gontcharov, 2010)

    NASA Astrophysics Data System (ADS)

    Gontcharov, G. A.

    2016-07-01

    A three-dimensional reddening map for stars within 1100pc of the Sun are presented. Analysis of the distribution of 70 million stars from the 2MASS catalog with the most accurate photometry on the (J-Ks)-Ks diagram supplemented with Monte Carlo simulations has shown that one of the maxima of this distribution corresponds to F-type dwarfs and subgiants with a mean absolute magnitude MKs=2.5m. The shift of this maximum toward large (J-Ks) with increasing Ks reflects the reddening of these stars with increasing heliocentric distance. The distribution of the sample of stars over Ks, l, and b cells with a statistically significant number of stars in each cell corresponds to their distribution over three-dimensional spatial cells. As a result, the reddening E(J-Ks) has been determined with an accuracy of 0.03m for spatial cells with a side of 100pc. All of the known large absorbing clouds within 1100pc of the Sun have manifested themselves in the results obtained. The absorbing matter of the Gould Belt is shown to manifest itself at latitudes up to 40° and within 600pc of the Sun. The size and influence of the Gould Belt may have been underestimated thus far. The absorbing matter at latitudes up to 60° and within 1100pc of the Sun has been found to be distributed predominantly in the first and second quadrants in the southern hemisphere and in the third and fourth quadrants in the northern hemisphere. Also the data of the Rv (2012AstL...38...12G) and Av (2012AstL...38...87G) 3D maps are added. (1 data file).

  2. Photographic surface photometry of the Milky Way. III - Photometry of the central area of the Galaxy in the ultraviolet

    NASA Astrophysics Data System (ADS)

    Proell, H. J.; Schmidt-Kaler, T.; Schlosser, W.

    1983-01-01

    6 photographic plates, taken at La Silla, Chile, with the spherical mirror super-wide-angle camera of the Astronomisches Institut der Ruhr Universität Bochum (see paper I: Schmidt-Kaler, Th. et al., 1982) were measured to study the surface brightness distribution in the area around the centre of the Milky Way, between galactic longitudes 297° and 27°, and latitudes - 30° to + 30°, with an angular resolution of 0.°3 × 0.°3 (Fig. 5). In section 2 the plate material and details of the reductions are presented, so far as not already given in paper I. During the photometric scanning of the plates all stars brighter than a limiting magnitude mlim were marked by hand, and the corresponding data points were replaced by an average from neighbouring points (section 3). Defined at the level of 50% elimination, mlim ≌ 8.m0 (in U). Figure 4 shows the effect of various methods of eliminating bright stars. The errors of the surface photometry are discussed in section 4. The internal mean error of the intensity of one data point, as determined from the scatter from the 6 plates, is ± 9.4%. This error is split into an additive component ± 8 S10U (S10 = intensity of a star of 10m), mostly due to the contributions of airglow and scattered light, and a multiplicative component of ± 7.5%, mostly due to the uncertainty of the photographic characteristic curve. Possible systematic errors are estimated and upper limits for these are given in table II. Section 5 presents the results of the photometry. For the sake of clear representation in the isophote map (Fig 5) data with intermediate intensities 110 < Igal ≦ 250 S10U were smoothed over 0.°9 × 0.°9, data with Igal ≦ 110 S10U were smoothed over 1.°2 × 1.°2. The mean error of the isophotes is about ± 6%. We then compare our photometry with existing ultraviolet surface photometries. Apart from the area l = 320° to 330°, b = -25° to -20° where our intensities are probably vitiated by some remaining airglow

  3. Comparison of ozone determinations by ultraviolet photometry and gas-phase titration

    NASA Technical Reports Server (NTRS)

    Demore, W. B.; Patapoff, M.

    1976-01-01

    A comparison of ozone determinations based on ultraviolet absorption photometry and gas-phase titration (GPT) shows good agreement between the two methods. Together with other results, these findings indicate that three candidate reference methods for ozone, UV photometry, IR photometry, and GPT are in substantial agreement. However, the GPT method is not recommended for routine use by air pollution agencies for calibration of ozone monitors because of susceptibility to experimental error.

  4. MULTI-COLOR TRANSIT PHOTOMETRY OF GJ 1214b THROUGH BJHK{sub s} BANDS AND A LONG-TERM MONITORING OF THE STELLAR VARIABILITY OF GJ 1214

    SciTech Connect

    Narita, Norio; Hori, Yasunori; Onitsuka, Masahiro; Sukom, Amnart; Tamura, Motohide; Suenaga, Takuya; Takahashi, Yasuhiro H.; Fukui, Akihiko; Kuroda, Daisuke; Yanagisawa, Kenshi; Ikoma, Masahiro; Kurosaki, Kenji; Kawashima, Yui; Nagayama, Takahiro; Nakajima, Yasushi; Hirano, Teruyuki; Kawauchi, Kiyoe; Kuzuhara, Masayuki; Ohnuki, Hiroshi; Izumiura, Hideyuki; and others

    2013-08-20

    We present five new transit light curves of GJ 1214b taken in the BJHK{sub s} bands. Two transits were observed in the B band using the Subaru Prime Focus Camera (Suprime-Cam) and the Faint Object Camera and Spectrograph (FOCAS) instruments on board the Subaru 8.2 m telescope, and one transit was done in the JHK{sub s} bands simultaneously with the Simultaneous Infrared Imager for Unbiased Survey (SIRIUS) camera on the Infrared Survey Facility (IRSF) 1.4 m telescope. Markov Chain Monte Carlo analyses show that the planet-to-star radius ratios are R{sub p}/R{sub s} = 0.11651 {+-} 0.00065 (B band, Subaru/Suprime-Cam), R{sub p}/R{sub s} = 0.11601 {+-} 0.00117 (B band, Subaru/FOCAS), R{sub p}/R{sub s} = 0.11654 {+-} 0.00080 (J band, IRSF/SIRIUS), R{sub p}/R{sub s}= 0.11550{sup +0.00142}{sub -0.00153} (H band, IRSF/SIRIUS), and R{sub p}/R{sub s} = 0.11547 {+-} 0.00127 (K{sub s} band, IRSF/SIRIUS). The Subaru Suprime-Cam transit photometry shows a possible spot-crossing feature. Comparisons of the new transit depths and those from previous studies with the theoretical models by Howe and Burrows suggest that the high molecular weight atmosphere (e.g., 1% H{sub 2}O + 99% N{sub 2}) models are most likely, however, the low molecular weight (hydrogen-dominated) atmospheres with extensive clouds are still not excluded. We also report a long-term monitoring of the stellar brightness variability of GJ 1214 observed with the MITSuME 50 cm telescope in the g', R{sub c}, and I{sub c} bands simultaneously. The monitoring was conducted for 32 nights spanning 78 nights in 2012, and we find a periodic brightness variation with a period of P{sub s} = 44.3 {+-} 1.2 days and semi-amplitudes of 2.1% {+-} 0.4% in the g' band, 0.56% {+-} 0.08% in the R{sub c} band, and 0.32% {+-} 0.04% in the I{sub c} band.

  5. Photometry and spectroscopy of the central star of the Trifid nebula

    NASA Astrophysics Data System (ADS)

    Kohoutek, L.; Mayer, P.; Lorenz, R.

    1999-01-01

    UBV photometry of the central star of the Trifid nebula - HD 164492, which has so far been suspected of photometric as well as of radial velocity variability - is presented. The results of our photometry do not confirm any variability. Moreover, based on new high resolution CCD spectra any radial velocity variability can be discarded. Photometry of several other members of the multiple stellar system is included; according to this photometry, the system is a physical one. Equivalent widths for the main component of HD 164492 are given. Positions measured on CCD exposures are presented too. Based on observations collected at the European Southern Observatory, La Silla, Chile.

  6. High-precision photometry for K2 Campaign 1

    NASA Astrophysics Data System (ADS)

    Huang, C. X.; Penev, K.; Hartman, J. D.; Bakos, G. Á.; Bhatti, W.; Domsa, I.; de Val-Borro, M.

    2015-12-01

    The two reaction wheel K2 mission promises and has delivered new discoveries in the stellar and exoplanet fields. However, due to the loss of accurate pointing, it also brings new challenges for the data reduction processes. In this paper, we describe a new reduction pipeline for extracting high-precision photometry from the K2 data set, and present public light curves for the K2 Campaign 1 target pixel data set. Key to our reduction is the derivation of global astrometric solutions from the target stamps, from which accurate centroids are passed on for high-precision photometry extraction. We extract target light curves for sources from a combined UCAC4 and EPIC catalogue - this includes not only primary targets of the K2 campaign 1, but also any other stars that happen to fall on the pixel stamps. We provide the raw light curves, and the products of various detrending processes aimed at removing different types of systematics. Our astrometric solutions achieve a median residual of ˜0.127 arcsec. For bright stars, our best 6.5 h precision for raw light curves is ˜20 parts per million (ppm). For our detrended light curves, the best 6.5 h precision achieved is ˜15 ppm. We show that our detrended light curves have fewer systematic effects (or trends, or red-noise) than light curves produced by other groups from the same observations. Example light curves of transiting planets and a Cepheid variable candidate, are also presented. We make all light curves public, including the raw and detrended photometry, at http://k2.hatsurveys.org.

  7. MOST photometry of the enigmatic PMS pulsator HD 142666

    NASA Astrophysics Data System (ADS)

    Zwintz, K.; Kallinger, T.; Guenther, D. B.; Gruberbauer, M.; Huber, D.; Rowe, J.; Kuschnig, R.; Weiss, W. W.; Matthews, J. M.; Moffat, A. F. J.; Rucinski, S. M.; Sasselov, D.; Walker, G. A. H.; Casey, M. P.

    2009-02-01

    Context: Modeling of pre-main sequence (PMS) stars through asteroseismology of PMS p-mode pulsators has only recently become possible, and spacebased photometry is one of the important sources of data for these efforts. We present precise photometry of the pulsating Herbig Ae star HD 142666 obtained in two consecutive years with the MOST (Microvariability & Oscilations of STars) satellite. Aims: Previously, only a single pulsation period was known for HD 142666. The MOST photometry reveals that HD 142666 is multi-periodic. However, the unique identification of pulsation frequencies is complicated by the presence of irregular variability caused by the star's circumstellar dust disk. The two light curves obtained with MOST in 2006 and 2007 provided data of unprecedented quality to study the pulsations in HD 142666 and also to monitor the circumstellar variability. Methods: Frequency analysis was performed using the routine sigspec and the results from the 2006 and 2007 campaigns were then compared to each other with the software cinderella to identify frequencies common to both light curves. The correlated frequencies were then submitted to an asteroseismic analysis. Results: We attribute 12 frequencies to pulsation. Model fits to the three frequencies with the highest amplitudes lie well outside the uncertainty box for the star's position in the HR diagram based on published values. Some of the frequencies appear to be rotationally split modes. Conclusions: The models suggest that either (1) the published estimate of the luminosity of HD 142666, based on a relation between circumstellar disk radius and stellar luminosity, is too high and/or (2) additional physics such as mass accretion may be needed in our models to accurately fit both the observed frequencies and HD 142666's position in the HR diagram. Based on data from the MOST satellite, a Canadian Space Agency mission, jointly operated by Dynacon Inc., the University of Toronto Institute for Aerospace Studies

  8. Preliminary results on interstellar reddening as deduced from filter photometry

    NASA Technical Reports Server (NTRS)

    Laget, M.

    1972-01-01

    Filter photometry has been used to derive the interstellar reddening law from stars through the study of a single spectral type, B0. The deficiency in the far ultraviolet flux of a supergiant relative to a main sequence star is compared with the difference in the flux distribution due to a change of one spectral class. Individual interstellar reddening curves show the general feature reported by Stecher (1969) and by Bless and Savage (1970). There is a large amount of scatter in the far ultraviolet which may be partially due to a real difference in interstellar extinction and partially due to observational inaccuracy.

  9. Refined flicker photometry technique to measure ocular lens density.

    PubMed

    Teikari, Petteri; Najjar, Raymond P; Knoblauch, Kenneth; Dumortier, Dominique; Cornut, Pierre-Loïc; Denis, Philippe; Cooper, Howard M; Gronfier, Claude

    2012-11-01

    Many physiological and pathological conditions are associated with a change in the crystalline lens transmittance. Estimates of lens opacification, however, generally rely on subjective rather than objective measures in clinical practice. The goal of our study was to develop an improved psychophysical heterochromatic flicker photometry technique combined with existing mathematical models to evaluate the spectral transmittance of the human ocular media noninvasively. Our results show that it is possible to accurately estimate ocular media density in vivo in humans. Potential applications of our approach include basic research and clinical settings on visual and nonimage-forming visual systems.

  10. Photometry of Multiple Stellar Populations in Globular Clusters

    NASA Astrophysics Data System (ADS)

    Milone, Antonino

    2012-05-01

    An increasing number of observations over the last years have shown the existence of distinct sub-populations in many (maybe all) globular clusters and shattered the paradigm of globulars hosting single, simple stellar populations. These multiple populations manifest themselves in a split of different evolutionary sequences in the cluster color-magnitude diagrams. Using filters covering an appropriate range of wavelengths, photometry splits the main sequence into two or more branches, and in many cases this bimodality is repeated in the subgiant and red giant regions, and on the horizontal branch. In this talk I will summarize the main results from photometric studies.

  11. U-band photometry of 17 WINGS clusters

    NASA Astrophysics Data System (ADS)

    Omizzolo, A.; Fasano, G.; Reverte Paya, D.; De Santis, C.; Grado, A.; Bettoni, D.; Poggianti, B.; D'Onofrio, M.; Moretti, A.; Varela, J.; Fritz, J.; Gullieuszik, M.; Cava, A.; Grazian, A.; Moles, M.

    2014-01-01

    Context. This paper belongs to a series presenting the WIde Field Nearby Galaxy-cluster Survey (WINGS). The WINGS project has collected wide-field, optical (B, V), and near-infrared (J, K) imaging as well as medium resolution spectroscopy of galaxies in a sample of 76 X-ray selected nearby clusters (0.04 photometry of galaxies and stars in the fields of 17 clusters of the WINGS sample. We also extend the original B- and V-band photometry (WINGS-OPT) for 9 and 6 WINGS clusters to a larger field of view. Methods: We used both the new and already existing B-band photometry to obtain reliable (U - B) colors of galaxies within three fixed apertures in kpc. To this aim, we took particular care with the astrometric precision in the reduction procedure. Since not all the observations were taken in good transparency conditions, the photometric calibration was partly obtained by relying on the SDSS and WINGS-OPT photometry for the U- and optical bands, respectively. Results: We provide U-band (also B- and V-band, where possible) total magnitudes of stars and galaxies in the fields of clusters. For galaxies only, the catalogs also provide geometrical parameters and carefully centered aperture magnitudes. The internal consistency of magnitudes was checked for clusters imaged with different cameras, while the external photometric consistency was obtained by comparison with the WINGS-OPT and SDSS surveys. Conclusions: The photometric catalogs presented here add the U-band information to the WINGS database for extending the spectral energy distribution of the galaxies, in particular in the ultraviolet wavelengths which are fundamental for deriving the star formation rate properties. Photometric catalogs are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc

  12. UBV photometry of ten southern hemisphere active-chromosphere stars

    NASA Technical Reports Server (NTRS)

    Bopp, Bernard W.; Africano, John; Quigley, Robert

    1986-01-01

    High-precision UBV photometry of ten southern hemisphere active-chromosphere stars with strong Ca II H and K and/or H-alpha emission has been obtained. Eight of these stars showed variability during June 1985. Complete or partial light curves are presented for the stars, and these data, as well as mean V magnitudes and colors, are compared with the results of other investigators. In a number of cases, significant changes in photometric amplitude are found, which may serve to track the formation and evolution of active regions on these stars.

  13. CCD-photometry of comets at large heliocentric distances

    NASA Technical Reports Server (NTRS)

    Mueller, Beatrice E. A.

    1992-01-01

    CCD imaging and time series photometry are used to determine the state of activity, nuclear properties and eventually the rotational motion of cometary nuclei. Cometary activity at large heliocentric distances and mantle evolution are not yet fully understood. Results of observations carried out at the 2.1 telescope on Kitt Peak April 10-12 and May 15-16, 1991 are discussed. Color values and color-color diagrams are presented for several comets and asteroids. Estimations of nuclear radii and shapes are given.

  14. Coordinates and RI photometry of Large Magellanic Cloud carbon stars

    SciTech Connect

    Costa, E. )

    1990-07-01

    Coordinates and photoelectric RI magnitudes are given for 86 carbon stars discovered by Blanco et al. in four selected 0.12 deg sq areas of the LMC. A comparison with the photometry of Blanco et al. for carbon stars in three different fields of the LMC suggests that the luminosity distribution of the carbon stars may change from center to center in the LMC. This possibility is supported by the differences in the mean I magnitude of the carbon stars detected between the four areas studied. 16 refs.

  15. MYRaf: An Easy Aperture Photometry GUI for IRAF

    NASA Astrophysics Data System (ADS)

    Niaei, M. S.; KiliÇ, Y.; Özeren, F. F.

    2015-07-01

    We describe the design and development of MYRaf, a GUI (Graphical User Interface) that aims to be completely open-source under General Public License (GPL). MYRaf is an easy to use, reliable, and a fast IRAF aperture photometry GUI tool for those who are conversant with text-based software and command-line procedures in GNU/Linux OSs. MYRaf uses IRAF, PyRAF, matplotlib, ginga, alipy, and SExtractor with the general-purpose and high-level programming language Python, and uses the Qt framework.

  16. EUVE photometry of SS Cygni: Dwarf nova outbursts and oscillations

    SciTech Connect

    Mauche, C.W.

    1995-05-15

    The authors present EUVE Deep Survey photometry and AAVSO optical measurements of the 1993 August and 1994 June/July outbursts of the dwarf nova SS Cygni. The EUV and optical light curves are used to illustrate the different response of the accretion disk to outbursts which begin at the inner edge and propagate outward, and those which begin at the outer edge and propagate inward. Furthermore, the authors describe the properties of the quasi-coherent 7--9 s sinusoidal oscillations in the EUV flux detected during the rise and plateau stages of these outbursts.

  17. LEMON: an (almost) completely automated differential-photometry pipeline

    NASA Astrophysics Data System (ADS)

    Terrón, V.; Fernández, M.

    2011-11-01

    We present LEMON, the CCD differential-photometry pipeline, written in Python, developed at the Institute of Astrophysics of Andalusia (CSIC) and originally designed for its use at the 1.23 m CAHA telescope for automated variable stars detection and analysis. The aim of our tool is to make it possible to completely reduce thousands of images of time series in a matter of hours and with minimal user interaction, if not none at all, automatically detecting variable stars and presenting the results to the astronomer.

  18. (abstract) Reddening Measurements using CCD uvby (Stromgren) Photometry

    NASA Technical Reports Server (NTRS)

    Andersson, B-G.; Pettersson, B.; Wannier, P. G.

    1993-01-01

    Reddening measurements for interstellar clouds have usually relied on one of two techniques: Star counts or spectro-photometric measurements. We present preliminary results for a technique to determine the extinction using CCD uvby (Stromgren) photometry, without the need to perform special classification of the stars. The method relies on the fact that the uvby system allows two independent measurements of the reddening through the m(sub 1)and c(sub 1) indices to select the true intrensic colors for each star. Using observations from the Burrell Schmidt on Kitt Peak, we find that the technique allows reliable reddening measurements to be made down to at least V=15&supm;.

  19. New Release of the BSM Epoch Photometry Database

    NASA Astrophysics Data System (ADS)

    Henden, A.

    2016-06-01

    (Abstract only) The Bright Star Monitor (BSM) Epoch Photometry Database (EPD) is a searchable catalog of all observations made by one of the AAVSO's five BSM systems. The newest release of this database contains some 100 million datasets, from both northern and southern hemispheres, taken over the last six years. These have been calibrated by both nightly visits to Landolt standard fields as well as through the use of the Tycho2 photometric catalog. The paper will describe how the observations were made, how to access the catalog, and the limitations to the photometric accuracy. Some examples of well-studied fields will be shown.

  20. Optical photometry and spectroscopy of Nova Del 2013

    NASA Astrophysics Data System (ADS)

    Tomov, T.; Ilkiewicz, K.; Swierczynski, E.; Belcheva, M.; Dimitrov, D.

    2013-08-01

    We report optical BV photometry and spectroscopy of Nova Del 2013, carried out between August 14.88 UT and August 15.08 UT. Using a 60 cm Cassegrain telescope at the Nicolaus Copernicus University Observatory (Torun, Poland) we estimated the V brightness of the Nova to be 6.31+/-0.02 mag and 6.18+/-0.03 mag on Aug. 14.94 UT and Aug. 15.02 UT respectively. HD 194113 (F2, V=8.00 mag) was used as a comparison star.

  1. uvby photometry in McCormick proper motion fields

    NASA Technical Reports Server (NTRS)

    Degewij, J.

    1982-01-01

    The Danish 50 cm telescope at the European Southern Observatory was used to obtain high-precision uvby photometry for 50 F2 to G2 stars, with V values in the 9.4-12.3 mag range, which were selected in the southern galactic polar regions of the McCormick proper motion fields and measured on six different nights. The brighter stars are found to systematically exhibit smaller m(1) indices, of about 0.02 mag, upon comparison with the earlier data of Blaauw et al (1976). Single measurements are given for 98 stars in eight McCormick fields at intermediate southern galactic latitudes.

  2. Multicolor photometry of triple system b Per requested

    NASA Astrophysics Data System (ADS)

    Waagen, Elizabeth O.

    2013-01-01

    Dr. Bob Zavala (U.S. Naval Observatory, Flagstaff) has requested AAVSO assistance in obtaining multicolor photometry of the bright triple system b Per in order to prepare for and detect a possible eclipse of the AB components by the C component predicted for 2013 January 23. Multi-color photometric observations of 4.5V b Per are requested 2013 January 23 through February 04. Based on a revised period of 702.45 ± 0.05 days, the next time of minimum light is predicted for HJD = 2456321.35 ± 0.05 (UT 2013 January 28 20:24UT ± 1.5 hours). The eclipse may last for up to four days, so the coverage requested will provide both a baseline out-of-eclipse light curve and a multi-color eclipse light curve for analysis. Photometry is needed at the level of 0.02-0.03 magnitude or better, as the eclipse may be as deep as 0.1 magnitude. For PEP observers, V coverage, and B if possible, is requested. DSLR observers should use whatever band(s) are available to them. Finder charts may be created using the AAVSO Variable Star Plotter (http://www.aavso.org/vsp). Observations should be submitted to the AAVSO International Database. See full Alert Notice for more details and links.

  3. A new look at photometry of the Moon

    USGS Publications Warehouse

    Goguen, J.D.; Stone, T.C.; Kieffer, H.H.; Buratti, B.J.

    2010-01-01

    We use ROLO photometry (Kieffer, H.H., Stone, T.C. [2005]. Astron. J. 129, 2887-2901) to characterize the before and after full Moon radiance variation for a typical highlands site and a typical mare site. Focusing on the phase angle range 45??. ) to calculate the scattering matrix and solve the radiative transfer equation for I/. F. The mean single scattering albedo is ??=0.808, the asymmetry parameter is ???cos. ?????=0.77 and the phase function is very strongly peaked in both the forward and backward scattering directions. The fit to the observations for the highland site is excellent and multiply scattered photons contribute 80% of I/. F. We conclude that either model, roughness or multiple scattering, can match the observations, but that the strongly anisotropic phase functions of realistic particles require rigorous calculation of many orders of scattering or spurious photometric roughness estimates are guaranteed. Our multiple scattering calculation is the first to combine: (1) a regolith model matched to the measured particle size distribution and index of refraction of the lunar soil, (2) a rigorous calculation of the particle phase function and solution of the radiative transfer equation, and (3) application to lunar photometry with absolute radiance calibration. ?? 2010 Elsevier Inc.

  4. Deep photometry and integral magnitudes of 8 nearby galaxies

    NASA Astrophysics Data System (ADS)

    Georgiev, Ts. B.

    2016-02-01

    We estimated integral magnitudes of galaxies trying to include the contribution of the brightest part of their halos. We performed surface photometry based on (i) concentric elliptical rims, corresponding to the peripheral ellipticity of the image, (ii) median estimation of the mean value of the rim pixels, (iii) apparent radial brightness profiles, corresponding to the rim medians, and (iv) magnitude curves of growth, derived by numerical integrations of the apparent rim profiles, without preliminary background estimation and removal. Furthermore, we used the magnitude curves of growth to determine the integral magnitudes (limited by size and deepness of our frames) and compared them with the total magnitudes in the data base HyperLeda. Also, we used the rim-profiles to estimate the background level far enough from the galaxy center and we build (here—only for trial) the intrinsic radial profiles (with background removal). We apply this photometry on 8 nearby galaxies, observed with CCD in the system BVRC IC by the 50 cm Schmidt telescope of the Rozhen NAO in 2003-2004. We build radial profiles which occur to be as average 1.8 times (1.2-2.5 times) larger than in data base NED and of integral brightness that occurs to be about 1.4 times (1.2-1.7 times) higher than in data base HyperLeda. The relative brightness additions, found here, correlate with the color index and anti-correlate with the luminosity of the galaxy.

  5. Far-ultraviolet stellar photometry: Fields in Sagittarius and Scorpius

    NASA Astrophysics Data System (ADS)

    Schmidt, Edward G.; Carruthers, George R.

    1995-02-01

    Far-ultraviolet photometry for 741 objects in a field in Sagittarius centered near M8 and 541 objects in a field centered near sigma Scorpii is presented. These data were extracted from electographic images obtained with two cameras during a shuttle flight in 1991 April/May. The cameras provided band passes with lambdaeff = 1375 A and lambdaeff = 1781 A. Synthetic colors show that these bands are sensitive to effective temperature for hot stars. Our measurements were placed on a quantitative far-ultraviolet magnitude scale by convolving the spectra of stars observed by IUE with our cameras' spectral response functions. Fifty-eight percent of the ultraviolet objects were identified with visible stars using the SIMBAD database while another 40% of the objects are blends of early type stars too close together to separate with our resolution. Our photometry is compared with that from the TD-1, OAO 2, and ANS satellites and the S201 (Apollo 16) far-ultraviolet camera and found to agree at the level of a few tenths of a magnitude. Unlike previous studies, almost half of the identified visual counterparts to the ultraviolet objects are early B stars. A plot of distance modulus against ultraviolet color excess reveals a significant population of stars with strong ultraviolet excess.

  6. Spectroscopy and photometry campaign on three bright Wolf Rayet stars

    NASA Astrophysics Data System (ADS)

    Waagen, Elizabeth O.

    2013-06-01

    Dr. Noel Richardson (Universite de Montreal) and colleagues have invited AAVSO observers to participate in an international professional-amateur spectroscopy and photometry campaign on the Wof Rayet stars WR 134, WR 135, and WR 137 (HD 191765, HD 192103, and HD 192641). The campaign has begun and runs through September 17, 2013. The purpose of the campaign is to study clumping aspects of the strong winds and changes present in large structures in the stellar winds in these WR stars. Spectroscopy and UBVRI time-series observations are requested. Supplemental targets to be observed if time permits are V905 Sco (HD 160529) and V4375 Sgr (HD 316285). Finder charts with sequences may be created using the AAVSO Variable Star Plotter (http://www.aavso.org/vsp). Photometry should be submitted to the AAVSO International Database. Details of the campaign are given at: http://www.stsci.de/wr134/index.htm. Instructions for sending spectroscopy data to Dr. Richardson are given at http! ://www.stsci.de/wr134/pdf/data_transfer.pdf.

  7. Optimal addition of images for detection and photometry

    NASA Technical Reports Server (NTRS)

    Fischer, Philippe; Kochanski, Greg P.

    1994-01-01

    In this paper we describe weighting techniques used for the optimal coaddition of charge coupled devices (CCD) frames with differing characteristics. Optimal means maximum signal to noise (S/N) for stellar objects. We derive formulas for four applications: (1) object detection via matched filter, (2) object detection identical to DAOFIND, (3) aperture photometry, and (4) ALLSTAR profile-fitting photometry. We have included examples involving 21 frames for which either the sky brightness or image resolution varied by a factor of 3. The gains in S/N were modest for most of the examples, except for DAOFIND detection with varying image resolution which exhibited a substantial S/N increase. Even though the only consideration was maximizing S/N, the image resolution was seen to improve for most of the variable resolution examples. Also discussed are empirical fits for the weighting and the availability of the program, WEIGHT, used to generate the weighting for the individual frames. Finally, we include appendices describing the effects of clipping algorithms and a scheme for star/galaxy and cosmic-ray/star discrimination. scheme for star/galaxy and cosmic-ray/star discrimination.

  8. UBV Photometry of the young open cluster Berkely 87

    NASA Astrophysics Data System (ADS)

    Akinyemi, Abolaji; Eskridge, Paul B.

    2015-01-01

    We obtained UBV imaging of a field in the young open cluster Berkeley 87. From these images, we measured the brightness of ~180 stars in the cluster. Our photometry was calibrated using published photometry (Turner & Forbes 1982 PASP 94, 789) of a subset of stars in our field. The cluster is in a region of the sky with strongly varying extinction. Therefore we made a (U-B)-(B-V) color-color diagram of the field and used this to de-redden the stars on a case by case basis. We de-reddened the stars using the unreddened supergiant and main sequence colors from Astrophysical Quantities (Cox 2000).The color-magnitude diagrams of the de-reddened stars are compared to the Padova isochrones(Marigo et al 2008 A&A 482 883). The isochrones are generated for a range of ages, with solar metalicity and no α enhancement. The best fit for the isochrones was the main sequence de-reddened stars from which the age of the cluster is estimated to be 20 million years. This is older than previous age estimates (1-5 million years) from earlier studies of the cluster. This may indicate age variation in the cluster.We acknowledge the support of the Physics and Astronomy department, and the College of Science and Engineering, Minnesota State University, Mankato.

  9. PHOTOMETRY OF VARIABLE STARS FROM DOME A, ANTARCTICA

    SciTech Connect

    Wang Lingzhi; Macri, Lucas M.; Krisciunas, Kevin; Wang Lifan; Ashley, Michael C. B.; Lawrence, Jon S.; Luong-Van, Daniel; Storey, John W. V.; Cui Xiangqun; Gong Xuefei; Yuan Xiangyan; Feng Longlong; Yang Ji; Zhu Zhenxi; Liu Qiang; Zhou Xu; Pennypacker, Carl R.; Shang Zhaohui; Yang Huigen; York, Donald G.

    2011-11-15

    Dome A on the Antarctic plateau is likely one of the best observing sites on Earth thanks to the excellent atmospheric conditions present at the site during the long polar winter night. We present high-cadence time-series aperture photometry of 10,000 stars with i < 14.5 mag located in a 23 deg{sup 2} region centered on the south celestial pole. The photometry was obtained with one of the CSTAR telescopes during 128 days of the 2008 Antarctic winter. We used this photometric data set to derive site statistics for Dome A and to search for variable stars. Thanks to the nearly uninterrupted synoptic coverage, we found six times as many variables as previous surveys with similar magnitude limits. We detected 157 variable stars, of which 55% were unclassified, 27% were likely binaries, and 17% were likely pulsating stars. The latter category includes {delta} Scuti, {gamma} Doradus, and RR Lyrae variables. One variable may be a transiting exoplanet.

  10. The MOST Asteroseismology Mission: Ultraprecise Photometry from Space

    NASA Astrophysics Data System (ADS)

    Walker, Gordon; Matthews, Jaymie; Kuschnig, Rainer; Johnson, Ron; Rucinski, Slavek; Pazder, John; Burley, Gregory; Walker, Andrew; Skaret, Kristina; Zee, Robert; Grocott, Simon; Carroll, Kieran; Sinclair, Peter; Sturgeon, Don; Harron, John

    2003-09-01

    The Microvariablity and Oscillations of Stars (MOST) mission is a low-cost microsatellite designed to detect low-degree acoustic oscillations (periods of minutes) with micromagnitude precision in solar-type stars and metal-poor subdwarfs. There are also plans to detect light reflected from giant, short-period, extrasolar planets and the oscillations of roAp stars and the turbulent variability in the dense winds of Wolf-Rayet stars. This paper describes the experiment and how we met the challenge of ultraprecise photometry despite severe constraints on the mass, volume, and power available for the instrument. A side-viewing, 150 mm aperture Rumak-Maksutov telescope feeds two frame-transfer CCDs, one for tracking and the other for science. There is a single 300 nm wide filter centered at 525 nm. Microlenses project Fabry images of the brighter (V<=10) target stars onto the science CCD. Fainter target stars will be focused directly elsewhere on the CCD. MOST was launched on 2003 June 30 into a low-Earth, Sun-synchronous, polar orbit allowing stars between -19° and +36° declination to be viewed continuously for up to 60 days. Attitude is controlled by reaction wheels and magnetotorquers. A solar safety shutter over the telescope diagonal is the only other moving part. Accumulated photometry will be used to calibrate response across the target field stop, and data will be compressed and downloaded to three dedicated ground stations.

  11. Surface photometry of a sample of elliptical and S0 galaxies

    SciTech Connect

    De carvalho, R.R.; Da costa, L.N.; Djorgovski, S. California Institute of Technology, Pasadena )

    1991-08-01

    The results are reported of surface photometry of 38 early-type galaxies, located mainly in the Fornax Cluster. Detailed comparisons with previously published work are given along with internal and external error estimates for all quantities, and some serious systematic discrepancies in the older aperture photometry of some of the galaxies in the present sample are pointed out. 15 refs.

  12. VizieR Online Data Catalog: Metallicity calibrations for UBV photometry (Karatas+, 2006)

    NASA Astrophysics Data System (ADS)

    Karatas, Y.; Schuster, W. J.

    2007-05-01

    UBV photometry [V, (B-V), (U-B)] has been collected from large data bases in conjunction with the derivation of intrinsic-colour, metallicity and absolute magnitude calibrations of F-, G- and early-K-type stars for uvby-beta photometry being derived by Karata & Schuster (in preparation). (2 data files).

  13. VizieR Online Data Catalog: [Fe/H] & VMAG calibrations for UBV photometry (Karatas+, 2006)

    NASA Astrophysics Data System (ADS)

    Karatas, Y.; Schuster, W. J.

    2007-05-01

    UBV photometry [V, (B-V), (U-B)] has been collected from large data bases in conjunction with the derivation of intrinsic-colour, metallicity and absolute magnitude calibrations of F-, G- and early-K-type stars for uvby-beta photometry being derived by Karata & Schuster (in preparation). (2 data files).

  14. Constraints on the Bulk Composition of Uranus from Herschel PACS and ISO LWS Photometry, SOFIA FORCAST Photometry and Spectroscopy, and Ground-Based Photometry of its Thermal Emission

    NASA Astrophysics Data System (ADS)

    Orton, Glenn; Mueller, Thomas; Burgdorf, Martin; Fletcher, Leigh; de Pater, Imke; Atreya, Sushil; Adams, Joseph; Herter, Terry; Keller, Luke; Sidher, Sunil; Sinclair, James; Fujiyoshi, Takuya

    2016-04-01

    We present thermal infrared observations of the disk of Uranus at 17-200 μm to deduce its global thermal structure and bulk composition. We combine 17-200 μm filtered photometric measurements by the Herschel PACS and ISO LWS instruments and 19-35 μm filtered photometry and spectroscopy by the SOFIA FORCAST instrument, supplemented by 17-25 μm ground-based photometric filtered imaging of Uranus. Previous analysis of infrared spectroscopic measurements of the disk of Uranus made by the Spitzer IRS instrument yielded a model for the disk-averaged temperature profile and stratospheric composition (Orton et al. 2014a Icarus 243,494; 2014b Icarus 243, 471) that were consistent with submillimeter spectroscopy by the Herschel SPIRE instrument (Swinyard et al. 2014, MNRAS 440, 3658). Our motivation to observe the 17-35 μm spectrum was to place more stringent constraints on the global para-H2 / ortho-H2 ratio in the upper troposphere and lower stratosphere than the ISO SWS results of Fouchet et al. (2003, Icarus 161, 127), who examined H2 quadrupole lines. We will discuss the consistency of these observations with a higher para-H2 fraction than implied by local thermal equilibrium, which would resolve a discrepancy between the Spitzer-based model and observations of HD lines by the Herschel PACS experiment (Feuchtgruber et al. 2013 Astron. & Astrophys. 551, A126). Constraints on the global para-H2 fraction allow for more precise analysis of the far-infrared spectrum, which is sensitive to the He:H2 ratio, a quantity that was not constrained by the Spitzer IRS spectra. The derived model, which assumed the ratio derived by the Voyager-2 IRIS/radio-science occultation experiment (Conrath et al. 1987 J. Geophys. Res. 92, 15003), is inconsistent with 70-200 μm PACS photometry (Mueller et al. 2016 Astron. & Astrophys. submittted) and ISO LWS photometric measurements. However, the model can be made consistent with the observations if the fraction of He relative to H2 were

  15. VizieR Online Data Catalog: YSOVAR: infrared photometry in NGC 1333 (Rebull+, 2015)

    NASA Astrophysics Data System (ADS)

    Rebull, L. M.; Stauffer, J. R.; Cody, A. M.; Gunther, H. M.; Hillenbrand, L. A.; Poppenhaeger, K.; Wolk, S. J.; Hora, J.; Hernandez, J.; Bayo, A.; Covey, K.; Forbrich, J.; Gutermuth, R.; Morales-Calderon, M.; Plavchan, P.; Song, I.; Bouy, H.; Terebey, S.; Cuillandre, J. C.; Allen, L. E.

    2016-06-01

    We present the Young Stellar Object VARiability (YSOVAR) data for NGC1333. There are 701 objects (see Table1) with mid-infrared light curves in one or both warm Spitzer bands. All YSOVAR Spitzer light curve tabular data are available via the YSOVAR data delivery to the Infrared Science Archive (IRSA; http://irsa.ipac.caltech.edu/frontpage/). The sky observed by the two IRAC channels (3.6 and 4.5μm, or IRAC-1 and -2) fields of view is slightly offset with the central ~10'*10' region, centered on 03:29:06+31:19:30, covered by both channels. The observations were obtained under program ID61026, between 2011 October 10 and November 14 (~35 days). Near-infrared observations were obtained using the Peters Automated Infrared Imaging Telescope (PAIRITEL), which is an automated 1.3m telescope. PAIRITEL was located at the Whipple Observatory at Mt. Hopkins, Arizona; the same telescope and camera used for the northern part of 2MASS, PAIRITEL acquired simultaneous J, H, and Ks images. The observations of NGC1333 were obtained over 24 epochs from 2010 October 7 to 2012 November 19. We compiled additional photometry from several different sources. Early in the Spitzer mission, NGC1333 was observed by both the guaranteed time observations (GTOs) and the Cores-to-Disks (c2d) Legacy program (Evans et al. 2009, cat. J/ApJS/181/321), with both IRAC and the Multiband Imaging Photometer for Spitzer (MIPS). NGC1333 was covered in the Two-Micron All Sky Survey (2MASS; see cat II/246) and was also located in a field targeted by the long exposure 6X 2MASS program (see cat II/281). As described in Rebull 2015 (cat. J/AJ/150/17), we included these main 2MASS catalog and deeper 6X catalog near-infrared JHKs data into our database. We also include the ~30 deep JH space-based measurements from Greissl et al. (2007AJ....133.1321G). Chandra X-ray Observatory Advanced CCD Imaging Spectrometer for wide-field imaging (ACIS-I) observations of NGC1333 were first reported in Getman et al. 2002 (cat. J

  16. Time series photometry of faint cataclysmic variables with a CCD

    NASA Astrophysics Data System (ADS)

    Abbott, Timothy Mark Cameron

    1992-08-01

    I describe a new hardware and software environment for the practice of time-series stellar photometry with the CCD systems available at McDonald Observatory. This instrument runs suitable CCD's in frame transfer mode and permits windowing on the CCD image to maximize the duty cycle of the photometer. Light curves may be extracted and analyzed in real time at the telescope and image data are stored for later, more thorough analysis. I describe a star tracking algorithm, which is optimized for a timeseries of images of the same stellar field. I explore the extraction of stellar brightness measures from these images using circular software apertures and develop a complete description of the noise properties of this technique. I show that scintillation and pixelization noise have a significant effect on high quality observations. I demonstrate that optimal sampling and profile fitting techniques are unnecessarily complex or detrimental methods of obtaining stellar brightness measures under conditions commonly encountered in timeseries CCD photometry. I compare CCD's and photomultiplier tubes as detectors for timeseries photometry using light curves of a variety of stars obtained simultaneously with both detectors and under equivalent conditions. A CCD can produce useful data under conditions when a photomultiplier tube cannot, and a CCD will often produce more reliable results even under photometric conditions. I prevent studies of the cataclysmic variables (CV's) AL Com, CP Eri, V Per, and DO Leo made using the time series CCD photometer. AL Com is a very faint CV at high Galactic latitude and a bona fide Population II CV. Some of the properties of AL Com are similar to the dwarf nova WZ Sge and others are similar to the intermediate polar EX Hya, but overall AL Com is unlike any other well-studied cataclysmic variable. CP Eri is shown to be the fifth known interacting binary white dwarf. V Per was the first CV found to have an orbital period near the middle of the

  17. Adaptive Optics Photometry and Astrometry of Binary Stars

    NASA Astrophysics Data System (ADS)

    Roberts, Lewis C., Jr.; Turner, Nils H.; Bradford, L. William; ten Brummelaar, Theo A.; Oppenheimer, Ben R.; Kuhn, Jeff R.; Whitman, Kathryn; Perrin, Marshall D.; Graham, James R.

    2005-11-01

    We present astrometric and photometric measurements of 39 binary stars made with the adaptive optics system on the 3.6 m Advanced Electro-Optical System (AEOS) telescope, taken from 2002 November to 2003 March. The binaries have separations ranging from 0.08" to 5.11" and differential magnitudes ranging from 0.096 to 7.9. Also, we include a list of observations of 23 known binaries that we were unable to resolve. In the process of these measurements, we discovered three new companions to two previously known binary stars. We also discuss the effects of scintillation and anisoplanatism on measurements of binary star photometry in adaptive optics images. Suggestions on how to minimize these effects are then given. Based on observations made at the Maui Space Surveillance System operated by Detachment 15 of the US Air Force Research Laboratory's Directed Energy Directorate.

  18. Towards photometry pipeline of the Indonesian space surveillance system

    NASA Astrophysics Data System (ADS)

    Priyatikanto, Rhorom; Religia, Bahar; Rachman, Abdul; Dani, Tiar

    2015-09-01

    Optical observation through sub-meter telescope equipped with CCD camera becomes alternative method for increasing orbital debris detection and surveillance. This observational mode is expected to eye medium-sized objects in higher orbits (e.g. MEO, GTO, GSO & GEO), beyond the reach of usual radar system. However, such observation of fast moving objects demands special treatment and analysis technique. In this study, we performed photometric analysis of the satellite track images photographed using rehabilitated Schmidt Bima Sakti telescope in Bosscha Observatory. The Hough transformation was implemented to automatically detect linear streak from the images. From this analysis and comparison to USSPACECOM catalog, two satellites were identified and associated with inactive Thuraya-3 satellite and Satcom-3 debris which are located at geostationary orbit. Further aperture photometry analysis revealed the periodicity of tumbling Satcom-3 debris. In the near future, it is not impossible to apply similar scheme to establish an analysis pipeline for optical space surveillance system hosted in Indonesia.

  19. Asteroid models from photometry and complementary data sources

    NASA Astrophysics Data System (ADS)

    Kaasalainen, Mikko

    2016-05-01

    I discuss inversion methods for asteroid shape and spin reconstruction with photometry (lightcurves) and complementary data sources such as adaptive optics or other images, occultation timings, interferometry, and range-Doppler radar data. These are essentially different sampling modes (generalized projections) of plane-of-sky images. An important concept in this approach is the optimal weighting of the various data modes. The maximum compatibility estimate, a multi-modal generalization of the maximum likelihood estimate, can be used for this purpose. I discuss the fundamental properties of lightcurve inversion by examining the two-dimensional case that, though not usable in our three-dimensional world, is simple to analyze, and it shares essentially the same uniqueness and stability properties as the 3-D case. After this, I review the main aspects of 3-D shape representations, lightcurve inversion, and the inclusion of complementary data.

  20. Macular pigment and the edge hypothesis of flicker photometry.

    PubMed

    Bone, Richard A; Landrum, John T; Gibert, Jorge C

    2004-12-01

    Heterochromatic flicker photometry is commonly used to measure macular pigment optical density (MPOD) in the human retina. It has been proposed, and accepted by many, that the MPOD so measured represents the value at a retinal location corresponding to the edge of the flickering, circular stimulus. We have investigated this proposal by using a series of annular stimuli to determine the MPOD distribution in the central 1.5 degrees of the retina for both eyes of 10 subjects. The MPOD obtained using a 1.5 degrees circular stimulus matched the MPOD distribution at a retinal eccentricity that was always less than the stimulus radius, and averaged, for the 10 subjects, 51% of the stimulus radius. Similar results were obtained using a 1 degrees stimulus. Thus the edge hypothesis is inconsistent with our data. We suggest that involuntary eye movements may be responsible for an apparent edge effect.

  1. Astrometry and photometry in the globular cluster M2

    NASA Astrophysics Data System (ADS)

    Cudworth, Kyle M.; Rauscher, Bernard J.

    1987-04-01

    Proper motions and photometry have been obtained for 301 stars down to V = about 16 in the region of the globular cluster M2. Membership probabilities derived from the proper motions show that over 200 of these stars are highly probable cluster members, including a number of UV-bright stars. A few stars suspected of being field stars in a recent dynamical study of the cluster of Pryor et al. (1986) are confirmed to be nonmembers. The internal proper-motion dispersion has been detected and is clearly isotropic out to about 3 arcmin from the cluster center. The proper-motion and radial-velocity dispersions have been equated to yield a distance of 11.0 + or - 1.7 kpc independent of any standard-candle assumptions. An accurate position of the cluster center has been measured that differs markedly from that found by Shawl and White (1986). A large space velocity has been derived for the cluster.

  2. Photometry of stars in the Cas OB5 Associations

    NASA Astrophysics Data System (ADS)

    Tanriver, Mehmet; Keskin, Ahmet

    2016-07-01

    OB associations are a grouping of very young associations, contain 10-100 very hot massive stars, spectral types O and B. Also, the OB associations contain low and intermediate mass stars, too. Association members are believed to form within the same small volume inside a giant molecular cloud. Once the surrounding dust and gas is blown away, the remaining stars become not tied up and begin to drift separately. It is believed that the majority of all stars in the Milky Way were formed in OB associations. O type stars are short-lived, and will be at an end as supernovae after roundly a million years. OB associations are generally only a few million years in age or less. In this study, the photometry of UU Cas and field star which been Cas OB5 association member was carried out. Light curves and color diagrams are given in the study.

  3. Deep CCD photometry in globular clusters. VIII - M12

    SciTech Connect

    Sato, T.; Richer, H.B.; Fahlman, G.G. )

    1989-10-01

    Results are presented on UBV photometry, obtained using the Canada-France-Hawaii Telescope, for a single field (2.2 x 3.5 arcmin) located 3.5 arcmin from the center of the galactic globular cluster M12 (NGC 6218). The color-magnitude diagram (CMD) indicated a possible existence of a sequence of binary stars. The fundamental cluster parameters for M12 derived from the present data are E(B-V) = 0.23 + or - 0.04 and (m-M)V = 14.25 + or - 0.20. An overlay of the isochrones and the CMD yields a best-estimate age of 17 Gyr. 49 refs.

  4. SPITZER IRAC PHOTOMETRY FOR TIME SERIES IN CROWDED FIELDS

    SciTech Connect

    Novati, S. Calchi; Beichman, C.; Gould, A.; Fausnaugh, M.; Gaudi, B. S.; Pogge, R. W.; Wibking, B.; Zhu, W.; Poleski, R.; Yee, J. C.; Bryden, G.; Henderson, C. B.; Shvartzvald, Y.; Carey, S.; Udalski, A.; Pawlak, M.; Szymański, M. K.; Skowron, J.; Mróz, P.; Kozłowski, S.; Collaboration: Spitzer team; OGLE group; and others

    2015-12-01

    We develop a new photometry algorithm that is optimized for the Infrared Array Camera (IRAC) Spitzer time series in crowded fields and that is particularly adapted to faint or heavily blended targets. We apply this to the 170 targets from the 2015 Spitzer microlensing campaign and present the results of three variants of this algorithm in an online catalog. We present detailed accounts of the application of this algorithm to two difficult cases, one very faint and the other very crowded. Several of Spitzer's instrumental characteristics that drive the specific features of this algorithm are shared by Kepler and WFIRST, implying that these features may prove to be a useful starting point for algorithms designed for microlensing campaigns by these other missions.

  5. Millisecond optical photometry of the DQ Herculis objects

    NASA Technical Reports Server (NTRS)

    Imamura, James N.; Steiman-Cameron, Thomas Y.

    1988-01-01

    The results of millisecond optical photometry of the DQ Herculis stars EX Hya, H2252-035, V1223 Sgr, and AE Aqr obtained at the Las Campanas Observatory and Cerro Tololo Inter-American Observatory during the years 1985, 1986, and 1987 are reported. The data for coherent and incoherent features are searched for. Coherent features (other than those previously known) were not detected for frequencies between 0.1 and 250 Hz at 4-sigma upper limits of 0.05-0.4 percent. Evidence is not found for 1-3 s, quasi-coherent features. Such features have been detected in the optical emission of the AM Her objects AN UMa, EF Eri, and E1405-451. Because of the similarities between AM Her and DQ Her objects, it was suggested that such quasi-coherent features might also be found in the DQ Her objects.

  6. Results of the 2015 Mexican Asteroid Photometry Campaign

    NASA Astrophysics Data System (ADS)

    Sada, Pedro V.; Navarro-Meza, Samuel; Reyes-Ruiz, Mauricio; Olguin, Lorenzo L.; Saucedo, Julio C.; Loera-Gonzalez, Pablo

    2016-04-01

    The 2015 Mexican Asteroid Photometry Campaign was organized at the 2nd National Planetary Astrophysics Workshop held in 2015 March at the Universidad Autónoma de Nuevo León in Monterrey, México. Three asteroids were selected for coordinated observations from several Mexican observatories. We report full lightcurves for the main-belt asteroid 1084 Tamariwa (P = 6.195 ± 0.001 h) and near-Earth asteroid (NEA) 4055 Magellan (P = 7.479 ± 0.001 h). Asteroid 1466 Mundleria was also observed on eight nights but no lightcurve was obtained because of its faintness, a crowded field-of-view, and low amplitude (<0.03 mag).

  7. Three Years of Photometry of the Delta Cepheid T Vulpecula

    NASA Astrophysics Data System (ADS)

    Nguyen, H. T.; Kyaw, T. T.

    2004-12-01

    Three years of UBV photoelectric photometry are presented for the Delta Cepheid, T Vulpecula. The observations were made by the Phoenix-10 automatic photoelectric telescope at the Fairborn Observatory in southern Arizona. T Vul was observed on over 100 different nights during this three-year period. Determination of times of maxima is proceeding using the "master curve" technique suggested by David G. Turner (Saint Mary's University, Halifax). We are thankful for the assistance of Louis J. Boyd (Fairborn Observatory) for telescope operations, Michael A. Seeds (Franklin and Marshall College) for telescope management and initial automated data reduction, and Russell M. Genet (Orion Observatory) and James R. Mueller (California Polytechnic State University) for technical advice. We acknowledge financial support by the Orion Observatory (observation funds) and the Department of Mathematics, California Polytechnic State University (conference and travel funds).

  8. Recovering The Photometry Of Brighter Than Saturated Objects In SDSS

    NASA Astrophysics Data System (ADS)

    Dahab, William

    2007-05-01

    We present the results of a technique that recovers the integrity of the SDSS photometry from bright (m < 15) and/or saturated objects in the SDSS. Bright objects saturate the CCD used by the SDSS, with overabundant electrons spilling over to nearby pixels, resulting in bleed trails. The photometric pipeline should, and indeed does, effectively process these bleed trails yielding usable data. This technique filters objects based on their specific flags, and recovers the stellar locus in color-color space. Objects as bright as g = 13 were extremely well recovered, as well as much of the data down to g = 11. We used these data to search for blue, saturated objects, hoping to find bright quasars. No new quasars were discovered, but several previously known objects, including 3C 273, were. We did discover a new cataclysmic variable, demonstrating the viability of this technique in the search for new, bright objects.

  9. An interactive modular design for computerized photometry in spectrochemical analysis

    NASA Technical Reports Server (NTRS)

    Bair, V. L.

    1980-01-01

    A general functional description of totally automatic photometry of emission spectra is not available for an operating environment in which the sample compositions and analysis procedures are low-volume and non-routine. The advantages of using an interactive approach to computer control in such an operating environment are demonstrated. This approach includes modular subroutines selected at multiple-option, menu-style decision points. This style of programming is used to trace elemental determinations, including the automated reading of spectrographic plates produced by a 3.4 m Ebert mount spectrograph using a dc-arc in an argon atmosphere. The simplified control logic and modular subroutine approach facilitates innovative research and program development, yet is easily adapted to routine tasks. Operator confidence and control are increased by the built-in options including degree of automation, amount of intermediate data printed out, amount of user prompting, and multidirectional decision points.

  10. USING PHOTOMETRY TO PROBE THE CIRCUMSTELLAR ENVIRONMENT OF {delta} SCORPII

    SciTech Connect

    Jones, C. E.; Wiegert, P. A.; Cyr, R. P.; Halonen, R. J.; Tycner, C.; Henry, G. W.; Muterspaugh, M. W.

    2013-05-15

    We acquired Johnson BV photometry of the binary Be disk system {delta} Scorpii during its 2009, 2010, 2011, and 2012 observing seasons and used it to probe the innermost regions of the disk. We found that several disk building events have occurred during this time, resulting in an overall brightening in the V band and reddening of the system. In addition to these long-term trends, we found cyclical variability in each observing season on timescales between 60 and 100 days. We were able to reproduce the changes in the magnitude and color of {delta} Sco using our theoretical models and found that variable mass-loss rates in the range 2.5-7.0 Multiplication-Sign 10{sup -9} M{sub Sun} yr{sup -1} over {approx}35 days can reproduce the observed increase in brightness.

  11. Spitzer IRAC Photometry for Time Series in Crowded Fields

    NASA Astrophysics Data System (ADS)

    Calchi Novati, S.; Gould, A.; Yee, J. C.; Beichman, C.; Bryden, G.; Carey, S.; Fausnaugh, M.; Gaudi, B. S.; Henderson, C. B.; Pogge, R. W.; Shvartzvald, Y.; Wibking, B.; Zhu, W.; Spitzer Team; Udalski, A.; Poleski, R.; Pawlak, M.; Szymański, M. K.; Skowron, J.; Mróz, P.; Kozłowski, S.; Wyrzykowski, Ł.; Pietrukowicz, P.; Pietrzyński, G.; Soszyński, I.; Ulaczyk, K.; OGLE Group

    2015-12-01

    We develop a new photometry algorithm that is optimized for the Infrared Array Camera (IRAC) Spitzer time series in crowded fields and that is particularly adapted to faint or heavily blended targets. We apply this to the 170 targets from the 2015 Spitzer microlensing campaign and present the results of three variants of this algorithm in an online catalog. We present detailed accounts of the application of this algorithm to two difficult cases, one very faint and the other very crowded. Several of Spitzer's instrumental characteristics that drive the specific features of this algorithm are shared by Kepler and WFIRST, implying that these features may prove to be a useful starting point for algorithms designed for microlensing campaigns by these other missions.

  12. Interpretation of integrated-disk photometry of Callisto and Ganymede

    NASA Technical Reports Server (NTRS)

    Pang, K.; Ajello, J. M.; Lumme, K.; Bowell, E.

    1983-01-01

    The Lumme-Bowell (1981) theory has been used to interpret the integrated phase curves of Callisto and Ganymede, and it is noted that while the theory explains the brightness angles of these satellites up to about 80 deg solar phase angle, the observed brightness drops off at larger angles more rapidly than predicted. It is suggested that this discrepancy is due to the fact that single regolith particles must have phase functions which are much more elongated in the forward or backward scattering directions than is allowed for by the Lumme-Bowell theory. The hemispheric asymmetry in Callisto's surface texture can be explained by invoking the formation of an ice film on the trailing side, consistent with Voyager detailed photometry and thermometry of Callisto.

  13. A method for local rectification of 2MASS positions with UCAC4

    NASA Astrophysics Data System (ADS)

    Bustos Fierro, I. H.; Calderón, J. H.

    2016-04-01

    We propose to locally rectify 2MASS with respect to UCAC4 in order to diminish the systematic differences between these catalogs. We develop a rectification method that starts computing the weighted mean differences 2MASS-UCAC4 on a regular grid on the sky. The corrections that are later applied to 2MASS positions are obtained by a spline interpolation of the mean values calculated on the grid. The method is tested in four 3° × 3° fields in the ecliptical zone; after rectification in all of them the systematic differences are reduced well below the random differences. The 2MASS catalog rectified with the proposed method can be regarded as an extension of UCAC4 for astrometry, with an accuracy of around 90 mas in the positions, and with negligible systematic errors, for instance for the astrometric reduction of small field CCD images.

  14. Extended variational approach to the SU(2) mass gap on the lattice

    SciTech Connect

    Akeyo, J.O. ); Jones, H.F.; Parker, C.S. )

    1995-02-01

    The linear [delta] expansion is applied to a calculation of the SU(2) mass gap on the lattice. Our results compare favorably with the strong-coupling expansion and are in good agreement with recent Monte Carlo estimates.

  15. THE PANCHROMATIC HUBBLE ANDROMEDA TREASURY. X. ULTRAVIOLET TO INFRARED PHOTOMETRY OF 117 MILLION EQUIDISTANT STARS

    SciTech Connect

    Williams, Benjamin F.; Dalcanton, Julianne J.; Weisz, Daniel R.; Byler, Nell; Johnson, L. C. E-mail: jd@astro.washington.edu E-mail: lcjohnso@astro.washington.edu; and others

    2014-11-01

    We have measured stellar photometry with the Hubble Space Telescope Wide Field Camera 3 (WFC3) and Advanced Camera for Surveys in near ultraviolet (F275W, F336W), optical (F475W, F814W), and near infrared (F110W, F160W) bands for 117 million resolved stars in M31. As part of the Panchromatic Hubble Andromeda Treasury survey, we measured photometry with simultaneous point-spread function (PSF) fitting across all bands and at all source positions after precise astrometric image alignment (<5-10 mas accuracy). In the outer disk, the photometry reaches a completeness-limited depth of F475W ∼ 28, while in the crowded, high surface brightness bulge, the photometry reaches F475W ∼ 25. We find that simultaneous photometry and optimized measurement parameters significantly increase the detection limit of the lowest-resolution filters (WFC3/IR) providing color-magnitude diagrams (CMDs) that are up to 2.5 mag deeper when compared with CMDs from WFC3/IR photometry alone. We present extensive analysis of the data quality including comparisons of luminosity functions and repeat measurements, and we use artificial star tests to quantify photometric completeness, uncertainties and biases. We find that the largest sources of systematic error in the photometry are due to spatial variations in the PSF models and charge transfer efficiency corrections. This stellar catalog is the largest ever produced for equidistant sources, and is publicly available for download by the community.

  16. EXTENDED PHOTOMETRY FOR THE DEEP2 GALAXY REDSHIFT SURVEY: A TESTBED FOR PHOTOMETRIC REDSHIFT EXPERIMENTS

    SciTech Connect

    Matthews, Daniel J.; Newman, Jeffrey A.; Coil, Alison L.; Cooper, Michael C.; Gwyn, Stephen D. J. E-mail: janewman@pitt.edu E-mail: m.cooper@uci.edu

    2013-02-15

    This paper describes a new catalog that supplements the existing DEEP2 Galaxy Redshift Survey photometric and spectroscopic catalogs with ugriz photometry from two other surveys: the Canada-France-Hawaii Legacy Survey (CFHTLS) and the Sloan Digital Sky Survey (SDSS). Each catalog is cross-matched by position on the sky in order to assign ugriz photometry to objects in the DEEP2 catalogs. We have recalibrated the CFHTLS photometry where it overlaps DEEP2 in order to provide a more uniform data set. We have also used this improved photometry to predict DEEP2 BRI photometry in regions where only poorer measurements were available previously. In addition, we have included improved astrometry tied to SDSS rather than USNO-A2.0 for all DEEP2 objects. In total this catalog contains {approx}27, 000 objects with full ugriz photometry as well as robust spectroscopic redshift measurements, 64% of which have r > 23. By combining the secure and accurate redshifts of the DEEP2 Galaxy Redshift Survey with ugriz photometry, we have created a catalog that can be used as an excellent testbed for future photo-z studies, including tests of algorithms for surveys such as LSST and DES.

  17. Probing Accretion in Magnetic Cataclysmic Variables from High Time Resolution Optical Photometry and X-ray Observations from ASTROSAT

    NASA Astrophysics Data System (ADS)

    Buckley, David; Marsh, Tom; Revnivtsev, Mikhail; Bonnet-Bidaud, Jean-Marc; Mouchet, Martine; Pal Singh, Kulinder; Semena, Andrey; Dhillon, Vik; Breytenbach, Hannes; Irawati, Puji; Potter, Stephen

    2016-07-01

    We present results from an on-going program of high speed CCD photometry of magnetic cataclysmic variables (mCVs) aimed at characterizing their high frequency (˜0.1-10 Hz) optical variability. In particular, we have been actively attempting to detect Quasi-Periodic Oscillations in many Polars, indicative of shock instabilities in their accretion columns. We have used a variety of instruments for this purpose, including the EM-CCD based SHOC camera on the SAAO 1.9-m telescope, SALTICAM and BVIT on SALT and Ultraspec on the TNO 2.5-m telescope. While we have detected QPOs seen before in the systems V834 Cen and VV Pup, we have only found evidence for one new detection, namely for 2MASS J19283247-5001344, an eclipsing polar. This may indicate that QPOs are somewhat of a rarity in Polars. We have also seen evidence for lower frequency QPOs, with characteristic timescales of 10s of seconds to several minutes. In addition, we have been investigating the nature of the breaks in the Power Density Spectra (νF_ν) power law for Intermediate Polars (e.g. EX Hya). This may give clues to the size of the inner radius of the accretion disc, where the magnetosphere begins to dominate the accretion flow. Finally, results of our recent ASTROSAT program on mCVs will be discussed.

  18. The rotation period of Epsilon Eri from photometry of its starspots

    NASA Technical Reports Server (NTRS)

    Frey, Gary J.; Hall, Douglas S.; Mattingly, Phil; Robb, Steve; Wood, Jim; Zeigler, Kenneth; Grim, Bruce

    1991-01-01

    BV photometry at six observatories in 1988/1989 and 1989/1990 shows variability resulting from five starspots which lived 1 or 2 months each, had rotation periods in the range P between 10.0d and 12.3d, and had amplitudes in the range 0.01 m - 0.03 m. From the range in P it was possible to estimate k greater than 0.20 +/- 0.05 for the differential rotation coefficient. Ca II K-line photometry, polarimetry, and earlier photometry reported in the literature has also shown variability with periodicities in the same 10 d -12 d range.

  19. The AAVSO Photoelectric Photometry Program in Its Scientific and Socio-Historic Context

    NASA Astrophysics Data System (ADS)

    Percy, J. R.

    2012-06-01

    In this paper, I review the work of the AAVSO in the area of photoelectric photometry (PEP). This work was influenced by several trends: in science, in technology, and in the sociology of amateur astronomy. Through the 1980s, the AAVSO photoelectric photometry program competed with other such programs and, in recent years, has been overshadowed by CCD photometry programs. Nevertheless, the AAVSO PEP program has, through careful organization, motivation, and feedback, produced extensive scientific results, and can continue to do so. In the case of my own research, AAVSO PEP observations have also contributed significantly to the education of my students.

  20. A Pan-STARRS1-based recalibration of the Sloan Digital Sky Survey photometry

    NASA Astrophysics Data System (ADS)

    Finkbeiner, Douglas P.; Schlafly, E.; Green, G.

    2014-01-01

    We present a recalibration of the SDSS DR9 photometry with new flat fields and zero points derived from Pan-STARRS. Using PSF photometry of 60 million stars with 16 < r < 20, we obtain SDSS flat-field and amplifier gain corrections stable to 3 millimagnitudes (mmag) in g,r,i,z bands and 15 mmag in u band. We also identify transient non-photometric periods in SDSS ("contrails") based on photometric deviations co-temporal in SDSS bands. The recalibrated SDSS and PS1 photometry agree with systematics at the 7 mmag level.

  1. Optical Photometry of BY Cam Modeled Using a Multipolar Magnetic Field Structure

    NASA Astrophysics Data System (ADS)

    Morales, John; Mason, P. A.; Zhilkin, A.; Bisikalo, D. V.; Robinson, E. L.

    2014-01-01

    We present new high-speed broad-band optical photometry of the asynchronous polar (magnetic cataclysmic variable) BY Cam. Observations were obtained at the 2.1-m Otto Struve Telescope of McDonald observatory with 3s integration times. In an attempt to understand the complex changes in accretion flow geometry, we performed full 3D MHD simulations assuming a variety of white dwarf magnetic field structures including both aligned and non-aligned dipole plus quadrupole field components. We compare model predictions with photometry and various phases of the beat cycle and find that synthetic light curves derived from a multipolar field structure are consistent with the optical photometry.

  2. THE SOLAR NEIGHBORHOOD. XXIII. CCD PHOTOMETRIC DISTANCE ESTIMATES OF SCR TARGETS-77 M DWARF SYSTEMS WITHIN 25 pc

    SciTech Connect

    Winters, Jennifer G.; Henry, Todd J.; Jao, Wei-Chun; Subasavage, John P.; Finch, Charlie T.; Hambly, Nigel C. E-mail: thenry@chara.gsu.edu E-mail: jsubasavage@ctio.noao.edu E-mail: nch@roe.ac.uk

    2011-01-15

    We present CCD photometric distance estimates of 100 SCR (SuperCOSMOS RECONS) systems with {mu} {>=} 0.''18 yr{sup -1}, 29 of which are new discoveries previously unpublished in this series of papers. These distances are estimated using a combination of new VRI photometry acquired at CTIO and JHK magnitudes extracted from 2MASS. The estimates are improvements over those determined using photographic plate BRI magnitudes from SuperCOSMOS plus JHK, as presented in the original discovery papers. In total, 77 of the 100 systems investigated are predicted to be within 25 pc. If all 77 systems are confirmed to have {pi}{sub trig} {>=} 40 mas, this sample would represent a 23% increase in M dwarf systems nearer than 25 pc in the southern sky.

  3. Resolved photometry of extragalactic young massive star clusters

    NASA Astrophysics Data System (ADS)

    Larsen, S. S.; de Mink, S. E.; Eldridge, J. J.; Langer, N.; Bastian, N.; Seth, A.; Smith, L. J.; Brodie, J.; Efremov, Yu. N.

    2011-08-01

    Aims: We present colour-magnitude diagrams (CMDs) of young massive star clusters in several galaxies located well beyond the Local Group. The richness of these clusters allows us to obtain large samples of post-main sequence stars and test how well the observed CMDs are reproduced by canonical stellar isochrones. Methods: We use imaging of seven clusters in the galaxies NGC 1313, NGC 1569, NGC 1705, NGC 5236 and NGC 7793 obtained with the Advanced Camera for Surveys on board the Hubble Space Telescope and carry out PSF-fitting photometry of individual stars in the clusters. The clusters have ages in the range ~(5-50) × 106 years and masses of ~105 M⊙-106 M⊙. Although crowding prevents us from obtaining photometry in the inner regions of the clusters, we are still able to measure up to 30-100 supergiant stars in each of the richest clusters. The resulting CMDs and luminosity functions are compared with photometry of artificially generated clusters, designed to reproduce the photometric errors and completeness as realistically as possible. Results: In agreement with previous studies, our CMDs show no clear gap between the H-burning main sequence and the He-burning supergiant stars, contrary to predictions by common stellar isochrones. In general, the isochrones also fail to match the observed number ratios of red-to-blue supergiant stars, although the difficulty of separating blue supergiants from the main sequence complicates this comparison. In several cases we observe a large spread (1-2 mag) in the luminosities of the supergiant stars that cannot be accounted for by observational errors. We find that this spread can be reproduced by including an age spread of ~(10-30) × 106 years in the models. However, age spreads cannot fully account for the observed morphology of the CMDs and other processes, such as the evolution of interacting binary stars, may also play a role. Conclusions: Colour-magnitude diagrams can be successfully obtained for massive star

  4. Multicolor surface photometry of a sample of low luminosity radio galaxies

    NASA Astrophysics Data System (ADS)

    Sahu, Sheetal Kumar; Pandey, S. K.; Chakradhari, N. K.; Baburao Pandge, Mahadev

    2015-08-01

    We present a detailed multiband photometric study of five galaxies, selected from a sample of low luminosity early-type galaxies from B2 sample, which have mpg = 15.7, mV = 16.5, redshifts up to 0.2, radio powers P408 = 1023 - 1026.5 W Hz-1 and between 1022 - 1025 W Hz-1 at 1.4 GHz. We have used observed BVR and Hα images from IGO 2m telescope (Pune, India) and 2m HCT, Indian Astronomical Observatory (IAO Hanle, India), and archival multiband data from SDSS (ugriz), 2MASS (JHKs ), WISE, Spitzer (mid-IR), XMM, CHANDRA (X-ray), UV (GALEX) and radio from VLA, IRAM for this study.We used standard technique of surface photometry by fitting ellipses to the isophotes for studying the distribution of light in the galaxies by studying their surface brightness profiles, ellipticity profiles, position angle profiles, variation of center of isophotes along semi-major axis, shapes of isophotes, radial color gradients, twists in isophotes and fine structure variations from smooth light profile. The obtained surface brightness profiles are fitted to the core-Sersic model for decomposing the galaxy light profiles and quantify the radial stellar distributions of the sample galaxies.The multiband color index profiles, e.g. u-g, g-r, r-i, i-z, B-R, B-V, J-Hs , J-Ks , H-Ks , R-Ks , 3.4-4.6 μm, 4.6-12 μm (mid-IR) and FUV-NUV(UV), are obtained and combined with various maps e.g . unsharp-masked images, residual maps, quotient maps, dust extinction maps, Hα emission maps, CO intensity maps, diffuse X-ray emission maps and extinction curves of the galaxies to study the morphology, properties and physical correlations of different phases (e.g cool gas, dust, ionized gas and hot gases) of Inter Stellar Medium and to examine various star formation related processes in the galaxies.

  5. Improved LRG Selection Algorithms combining Optical And WISE (Infrared) Photometry

    NASA Astrophysics Data System (ADS)

    Prakash, Abhishek; Newman, J.; eBOSS Collaboration

    2014-01-01

    Luminous red galaxies (LRGs) are the most massive galaxies in nearby universe of z < 1.0 which appear to have formed the bulk of their stars at early times. Mostly ellipticals, they are associated with massive dark matter halos and hence cluster very strongly which makes them an excellent tracer of the large-scale structure of the Universe. LRGs at z < 0.6 can be selected efficiently using optical photometry, but at z >0.6 this becomes increasingly difficult. Here we present the results of new techniques now being applied to select LRGs at redshifts 0.6 < z < 1 utilizing SDSS and WISE photometry in combination. Old stellar populations exhibit a global maximum in their SED at a wavelength of 1.6 μm, commonly referred to as the '1.6 μm bump'. Since LRGs possess very few young stars, this feature generally dominates their overall spectral energy distribution. The lowest wavelength channel in WISE is centered at 3.4 μm, causing LRGs that are at 1 to be extremely bright in this band compared to the optical. As a result, the r-W1 vs. r-i color-color diagram (where W1 is the 3.4 μm WISE AB magnitude) provides an efficient tool for selecting high-redshift LRGs while avoiding stars. In this poster, we present new results from efforts to optimize the color cut used to select LRGs, yielding samples with a very low stellar contamination rate, but a high fraction of galaxies that are both at z>0.6 and intrinsically red in color. Studying their properties and distribution can also help us determine the mechanisms by which these rare objects form. We have tested this method using photometric redshifts and spectroscopic redshifts in the COSMOS field and DEEP2 fields respectively. LRGs selected with this method are the targets for future-generation surveys such as eBOSS and DESI and undergoing surveys like, SEQUELS BOSS ancillary survey which aim at high precision measurement of BAO.

  6. Infrared photometry and polarimetry of Cygnus X-3

    NASA Technical Reports Server (NTRS)

    Jones, Terry Jay; Gehrz, Robert D.; Kobulnicky, Henry A.; Molnar, Lawrence A.; Howard, Eric M.

    1994-01-01

    We present photometry and linear polarimetry of Cygnus X-3 at K (2.2 micrometers) obtained over a 5 yr period. Photometry and polarimetry at J, H, and K of nearby field stars is also presented. From an analysis of these data we find: (1) Using the x-ray ephemeris of Kitamoto et al. (ApJ, 384, 263 (1992), including the first and second derivatives of the period, the leading edge of the decline to minimum in the quiescent K light curve has not changed in phase since 1974. The duration of the minimum in the light curve has changed significantly between different epochs, becoming much broader in 1993 than it was previously. (2) In addition to an interstellar polarization component, it is likely Cyg X-3 has an intrinsic polarization component that is variable. The variations in the polarization do not show any diagnostic pattern with orbital phase. A crude analysis of the polarization suggests the intrinsic polarization of Cyg X-3 has a mean position angle of approximately 12 deg, nearly the same as the direction of the expanding radio lobes. This is consistent with circumstellar electrons scattering in an equatorial disk that is perpendicular to the lobe axis. (3) The mean position angle for the interstellar polarization in the direction of Cyg X-3 is 150 deg. This is nearly perpendicular to the axis of interstellar radio scattering seen in the extended (Very Long Baseline Inteferometry (VLBI) images. Since the position angle of interstellar polarization is the same as the projected magnetic field direction, this suggests the interstellar (not circumstellar) scattering must be taking place perpendicular to the interstellar magnetic field lines. (4) Cyg X-3 was observed at K during a flare on 1992 September 30 with a temporal resolution of 6 s. The flaring had rise and fall times of approximately 50 s with peak intensities up to 80 mJy. The flux between individual flare events never dropped to quiescent levels for the duration of our observations (approximately 2000 s).

  7. [Determination of lithium content in human biological objects (liver, kidney) by the method of flame photometry].

    PubMed

    Luzanova, I S; Voznesenskaia, T V; Menitskaia, V I; Pushchinskaia, E V

    2007-01-01

    The authors give a method of determination of the content of lithium in biological objects (liver, kidney) by the method of flame photometry. It is possible to use this method in forensic medicine in cases of acute intoxication.

  8. Spectroscopy and photometry of X Ser (Nova Ser 1903) during its current DN stunted outburst

    NASA Astrophysics Data System (ADS)

    Munari, U.; Dallaporta, S.

    2016-09-01

    The old nova X Ser (Nova Ser 1903) is known to display stunted dwarf-nova outbursts (Honeycutt et al. 1998, AJ 115, 2527), for which multiband photometry - and spectroscopy in particular - seem acutely rare.

  9. Photometric analysis of the eclipsing binary 2MASS 19090585+4911585

    NASA Astrophysics Data System (ADS)

    Raetz, St.; Vaňko, M.; Mugrauer, M.; Schmidt, T. O. B.; Roell, T.; Eisenbeiss, T.; Hohle, M. M.; Koeltzsch, A.; Ginski, Ch.; Marka, C.; Moualla, M.; Tetzlaff, N.; Broeg, Ch.; Neuhäuser, R.

    2009-05-01

    We report on observations of the eclipsing binary 2MASS 19090585+4911585 with the 25 cm auxiliary telescope of the University Observatory Jena. We show that a nearby brighter star (2MASS 19090783+4912085) was previously misclassified as the eclipsing binary and find 2MASS 19090585+4911585 to be the true source of variation. We present photometric analysis of V RI light curves. The system is an overcontact binary of W UMa type with an orbital period of (0.288374 ± 0.000010) d. Based on observations obtained with telescopes of the University Observatory Jena, which is operated by the Astrophysical Institute of the Friedrich-Schiller-University Jena.

  10. Geometry of the LMC Disk: Results from MACHO and 2MASS

    SciTech Connect

    Nikolaev, S; Drake, A; Keller, S; Cook, K; Dalal, N; Griest, K; Welch, D; Kanbur, S

    2003-11-04

    We have cross-correlated MACHO LMC Cepheids with 2MASS Second Incremental Release Catalog. The resulting database is considerably larger than the set of OGLE Cepheids in the LMC bar, and has significantly better areal coverage, allowing more accurate determination of LMC geometry. Random-phase correction is applied to 2MASS J, H, and Ks magnitudes, using the knowledge of V-band light curve and the ephemeris of 2MASS observations, to produce mean magnitudes. The improvement of phase-corrected PL relations over random-phase PL relations is clearly demonstrated. Reddening is estimated for each star individually, further improving the accuracy of the method. The orientation parameters of the LMC are derived by a Maximum Likelihood approach which solves for viewing angles and PL coefficients simultaneously, providing an unbiased estimation. The results of the analysis are used to place limits on warping of the LMC disk. Implications for the microlensing optical depth are also discussed.

  11. VizieR Online Data Catalog: WASP-104b and WASP-106b photometry (Smith+, 2014)

    NASA Astrophysics Data System (ADS)

    Smith, A. M. S.; Anderson, D. R.; Armstrong, D. J.; Barros, S. C. C.; Bonomo, A. S.; Bouchy, F.; Brown, D. J. A.; Collier, Cameron A.; Delrez, L.; Faedi, F.; Gillon, M.; Gomez Maqueo Chew, Y.; Hebrard, G.; Jehin, E.; Lendl, M.; Louden, T. M.; Maxted, P. F. L.; Montagnier, G.; Neveu-Vanmalle, M.; Osborn, H. P.; Pepe, F.; Pollacco, D.; Queloz, D.; Rostron, J. W.; Segransan, D.; Smalley, B.; Triaud, A. H. M. J.; Turner, O. D.; Udry, S.; Walker, S. R.; West, R. G.; Wheatley, P. J.

    2014-09-01

    The stars WASP-104 and WASP-106 were observed by SuperWASP-N from 2008 to 2011, and by WASP-South from 2009 to 2010. This differential survey photometry has been de-reddened and normalised. Further photometry was obtained using the TRAPPIST, Euler, Liverpool and Isaac Newton telescopes in 2013 and 2014. All these data are plotted in Figures 1 and 2. (1 data file).

  12. Color-magnitude diagram of Palomar 4 - CCD photometry

    NASA Astrophysics Data System (ADS)

    Christian, C. A.; Heasley, J. N.

    1986-04-01

    Photometry of the globular cluster Pal 4 was obtained with the RCA CCD camera on the 3.6 m Canada-France-Hawaii Telescope on Mauna Kea. The color-magnitude diagram of the cluster shows a well-defined red horizontal branch, typical of outer halo systems, and an asymptotic giant branch well separated from the giant branch. The population of Pal 4 has been sampled to the main-sequence turnoff region (V = 25), allowing a detailed comparison of this distant object with theoretical models. The cluster parameters consistent with the CCD data are (m - M)0 = 20.1 + or - 0.1 mag, E(B - V) = 0.02 + or - 0.02, and Fe/H forbidden line = -1.7 + or - 0.1 with Y =0.2. The age of the cluster, determined by comparison with the isochrones of VandenBerg and Bell (1985) is consistent with an age of 15 + or - 1 Gyr, similar to inner halo globular clusters with ages determined in the same way.

  13. The CCD photometry of the globular cluster Palomar 1.

    NASA Astrophysics Data System (ADS)

    Borissova, J.; Spassova, N.

    1995-04-01

    A CCD photometry of the halo cluster Palomar 1 is presented in the Thuan-Gunn photometric system. The principal sequences of the color-magnitude diagrams are delineated in different spectral bands. The color-magnitude diagrams of the cluster show a well defined red horizontal branch, a subgiant branch and a main-sequence down to about two magnitudes below the main sequence turnoff. The giant branch is absent and the brightest stars are the horizontal branch stars. The age of the cluster determined by comparison with the isochrones of Bell & Vanden Berg (1987) is consistent with an age in the interval 12-14Gyr. A distance modulus of (m-M)_g0_=15.38+/-0.15 magnitude and E(g-r)=0.16 has been derived. An estimate of the cluster structural parameters such as core radius and concentration parameter gives r_c_=1.5pc and c=1.46. A mass estimate of 1.1 10^3^Msun_ and a mass-to-light ratio of 1.79 have been obtained using King's (1966) method. The morphology of color-magnitude diagrams allows Pal 1 to be interpreted as probably a globular cluster rather than an old open one.

  14. Performance of Electroluminescent Flats for Precision Light Curve Photometry

    NASA Astrophysics Data System (ADS)

    Avril, Ryan L.; Oberst, T. E.

    2014-01-01

    We measure of the quality of flat field frames (flats) taken using an electroluminescent (EL) panel versus both dome and sky flats for purposes of calibrating visual CCD images. Classic dome and sky flats can both suffer from overall gradients and local irregularities. EL panel flats have recently grown in popularity as a third alternative, based partly on their potential to be free of such defects. We assess the flats based on their contributions to the RMS noise of long-duration light curves constructed via differential aperture photometry. The noise levels explored range from ~ 1 - few mmag, as needed for the ground-based detection of transiting planets. The target and reference stars are deliberately permitted to drift across the CCD in order to probe pixel-to-pixel variations. Both the filter and focus are varied during the tests - the former to probe color variation in the flats, and the latter because defocusing tends to average out pixel-to-pixel variations that the flats are intended to remove. All tests were performed at the Westminster College Observatory (WCO), which belongs to the Kilodegree Extremely Little Telescope (KELT)-North follow-up network.

  15. High-speed ultraviolet photometry of HD 60435

    NASA Technical Reports Server (NTRS)

    Taylor, M.; Nelson, M. J.; Bless, R. C.; Dolan, J. F.; Elliot, J. L.; Percival, J. W.; Robinson, E. L.; Van Citters, G. W.

    1993-01-01

    We present the first high-speed ultraviolet photometry of an oscillating Ap star, HD 60435. After removing known orbital effects related to the Hubble Space Telescope, we confirm the presence of a strong pulsation period at a frequency of 123.70 cycles per day. In addition, we find significant amplitude modulation of this frequency that we suggest could be the result of beating of multiple periodicities. In this context, we suggest evidence for the presence of four additional frequencies at nu = 120.56, 126.55, 149.49, and 221.03 cycles per day. Three of these frequencies correspond well to frequencies detected in optical observations of HD 60435. The fourth, at 149.49 cycles per day, if real, is a potentially new pulsation mode that has not been detected in ground-based observations of this star. The amplitude of the 123 cycles per day pulsation is significantly larger in the ultraviolet than it is in the blue.

  16. Counterphase modulation flicker photometry: phenotypic and genotypic associations.

    PubMed

    Lawrance-Owen, A J; Bosten, J M; Hogg, R E; Bargary, G; Goodbourn, P T; Mollon, J D

    2014-04-01

    The OSCAR test, a clinical device that uses counterphase flicker photometry, is believed to be sensitive to the relative numbers of long-wavelength and middle-wavelength cones in the retina, as well as to individual variations in the spectral positions of the photopigments. As part of a population study of individual variations in perception, we obtained OSCAR settings from 1058 participants. We report the distribution characteristics for this cohort. A randomly selected subset of participants was tested twice at an interval of at least one week: the test-retest reliability (Spearman's rho) was 0.80. In a whole-genome association analysis we found a provisional association with a single nucleotide polymorphism (rs16844995). This marker is close to the gene RXRG, which encodes a nuclear receptor, retinoid X receptor γ. This nuclear receptor is already known to have a role in the differentiation of cones during the development of the eye, and we suggest that polymorphisms in or close to RXRG influence the relative probability with which long-wave and middle-wave opsin genes are expressed in human cones.

  17. Controversies in ocular inflammation and immunology laser flare photometry.

    PubMed

    Wakefield, Denis; Herbort, Carl P; Tugal-Tutkun, Ilknur; Zierhut, Manfred

    2010-10-01

    Laser flare photometry (LFP) is a method used to detect flare in the anterior chamber (AC). Until now several laser flare photometers have been developed and are in use. LFP is not yet used in all major uveitis centres and, in order to understand this reluctance and know whether use of LFP is justified and should be recommended, an expert meeting was deemed necessary leading to this publication. Besides others results included the following: There is variation between users with regard to how many readings are necessary varying from 3 to 10. It appears appropriate to use at least 6-10 readings. LFP is most useful in patients with anterior uveitis. In patients with posterior and intermediate uveitis, at least 15 photons in the anterior chamber is considered the necessary threshold to be reliable to monitor evolution of inflammation. Factors influencing the measurement of LFP are cataract, corneal opacity, pupil size, intraocular lens and shallow anterior chamber but this is mostly irrelevant in pathological situation. LFP can be used to adjust the management of patients with uveitis, but not necessarily influence treatment. Exceptions may be patients with JIA and Behcet's Disease. LFP results should always be interpreted in conjunction with the usually clinical observations. There is some evidence that worsening of the flare on two consecutive visits is predictive of a relapse, especially in patients with Behcet's disease. LFP maybe also useful for predicting rejection of corneal transplant when the cornea is not thickened.

  18. A catalogue of helium abundance indicators from globular cluster photometry

    NASA Astrophysics Data System (ADS)

    Sandquist, Eric L.

    2000-04-01

    We present a survey of helium abundance indicators derived from a comprehensive study of globular cluster photometry in the literature. For each of the three indicators used, we conduct a thorough error analysis, and identify systematic errors in the computational procedures. For the population ratio RNHBNRGB, we find that there is no evidence of a trend with metallicity, although there appears to be real scatter in the values derived. Although this indicator is the one best able to provide useful absolute helium abundances, the mean value is Y~0.20, indicating the probable presence of additional systematic error. For the magnitude difference from the horizontal branch to the main sequence Δ and the RR Lyrae mass-luminosity exponent A, it is only possible to determine relative helium abundances reliably. This is due to continuing uncertainties in the absolute metallicity scale for Δ, and uncertainty in the RR Lyrae temperature scale for A. Both indicators imply that the helium abundance is approximately constant as a function of [Fe/H]. According to the A indicator, both Oosterhoff I and II group clusters have constant values independent of [Fe/H] and horizontal branch type. In addition, the two groups have slopes dlog/d[Fe/H] that are consistent with each other, but significantly smaller than the slope for the combined sample.

  19. Deep CCD photometry in globular clusters III. M15

    SciTech Connect

    Fahlman, G.G.; Richer, H.B.; Vandenberg, D.A.

    1985-06-01

    CCD photometry in U, B, and V is presented for a 5' x 3' field in the globular cluster M15. The location of the main sequence in the color-magnitude diagram is found here to be significantly bluer than previous studies have indicated. The luminosity function of the cluster is studied down to V = 22.8 (Mroughly-equal7.5) and shown to be consistent with a power-law mass function, n(M) = QM/sup -alpha/ with ..cap alpha.. = 2.5 +- 1.0, to the limit of our data. The field star population brighter than V = 21.5, is examined in some detail. There appears to be about 50% more stars belonging to the disk in the field as compared with the Bahcall-Soneira standard galaxy model. The reddening to the cluster is found to be E(B-V) = 0.11 +- 0.04 from nine bright field stars. A new value for the ultraviolet excess of the cluster main-sequence stars is obtained, delta(0.6) = 0.25 +- 0.02, and confirms the well-known fact that M15 is among the metal poorest of the globular clusters.

  20. Deep CCD photometry in globular clusters. VII. M30

    SciTech Connect

    Richer, H.B.; Fahlman, G.G.; Vandenberg, D.A.

    1988-06-01

    New UBV CCD photometry in a single field of the globular cluster M30 was obtained, and the data were used to obtain the color magnitude diagram (CMD) of the cluster, its luminosity function, and to derive fundamental cluster parameters. No blue stragglers were found, nor any evidence of a binary sequence in the data even though the field under study is only 21 core radii from the cluster center. The cluster reddening is observed to be 0.068 + or - 0.035, significantly higher than that adopted in most current papers on M30. An intercomparison of the CMDs of three very metal-poor clusters clearly shows that there is no evidence for any age difference between them. The age of M30 itself is found to be about 14 Gyr. The luminosity function of M30 is determined to be M(V) = 8. Comparison of this function with one found by Bolte (1987) at 65 core radii shows clear evidence of mass segregation in the low-mass stars. 44 references.

  1. High Precision Photometry of Bright Transiting Exoplanet Hosts

    NASA Astrophysics Data System (ADS)

    Wilson, Maurice; Eastman, Jason; Johnson, John A.

    2016-01-01

    Within the past two decades, the successful search for exoplanets and the characterization of their physical properties have shown the immense progress that has been made towards finding planets with characteristics similar to Earth. For most exoplanets with a radius about the size of Earth, evaluating their physical properties, such as the mass, radius and equilibrium temperature, cannot be determined with satisfactory precision. The MINiature Exoplanet Radial Velocity Array (MINERVA) was recently built to obtain spectroscopic and photometric measurements to find, confirm, and characterize Earth-like exoplanets. MINERVA's spectroscopic survey targets the brightest, nearby stars which are well-suited to the array's capabilities, while its primary photometric goal is to search for transits around these bright targets. Typically, it is difficult to find satisfactory comparison stars within a telescope's field of view when the primary target is very bright. This issue is resolved by using one of MINERVA's telescopes to observe the primary bright star while the other telescopes observe a distinct field of view that contains satisfactory bright comparison stars. We describe the code used to identify nearby comparison stars, schedule the four telescopes, produce differential photometry from multiple telescopes, and show the first results from this effort.This work has been funded by the Ronald E. McNair Post-Baccalaureate Achievement Program, the ERAU Honors Program, the ERAU Undergraduate Research Spark Fund, and the Banneker Institute at the Harvard-Smithsonian Center for Astrophysics.

  2. NEOWISE STUDIES OF ASTEROIDS WITH SLOAN PHOTOMETRY: PRELIMINARY RESULTS

    SciTech Connect

    Mainzer, A.; Masiero, J.; Bauer, J.; Hand, E.; Grav, T.; Mo, W.; Tholen, D. J.; McMillan, R. S.; Maleszewski, C.; Wright, E.; Watkins, J.; Spahr, T.; Cutri, R. M.; Walker, R.

    2012-01-20

    We have combined the NEOWISE and Sloan Digital Sky Survey data to study the albedos of 24,353 asteroids with candidate taxonomic classifications derived using Sloan photometry. We find a wide range of moderate to high albedos for candidate S-type asteroids that are analogous to the S complex defined by previous spectrophotometrically based taxonomic systems. The candidate C-type asteroids, while generally very dark, have a tail of higher albedos that overlaps the S types. The albedo distribution for asteroids with a photometrically derived Q classification is extremely similar to those of the S types. Asteroids with similar colors to (4) Vesta have higher albedos than the S types, and most have orbital elements similar to known Vesta family members. Finally, we show that the relative reflectance at 3.4 and 4.6 {mu}m is higher for D-type asteroids and suggest that their red visible and near-infrared spectral slope extends out to these wavelengths. Understanding the relationship between size, albedo, and taxonomic classification is complicated by the fact that the objects with classifications were selected from the visible/near-infrared Sloan Moving Object Catalog, which is biased against fainter asteroids, including those with lower albedos.

  3. RELATIVE PHOTOMETRY OF HAT-P-1b OCCULTATIONS

    SciTech Connect

    Beky, Bence; Holman, Matthew J.; Noyes, Robert W.; Sasselov, Dimitar D.; Gilliland, Ronald L.; Bakos, Gaspar A.; Winn, Joshua N.

    2013-06-01

    We present Hubble Space Telescope (HST) Space Telescope Imaging Spectrograph observations of two occultations of the transiting exoplanet HAT-P-1b. By measuring the planet to star flux ratio near opposition, we constrain the geometric albedo of the planet, which is strongly linked to its atmospheric temperature gradient. An advantage of HAT-P-1 as a target is its binary companion ADS 16402 A, which provides an excellent photometric reference, simplifying the usual steps in removing instrumental artifacts from HST time-series photometry. We find that without this reference star, we would need to detrend the lightcurve with the time of the exposures as well as the first three powers of HST orbital phase, and this would introduce a strong bias in the results for the albedo. However, with this reference star, we only need to detrend the data with the time of the exposures to achieve the same per-point scatter, therefore we can avoid most of the bias associated with detrending. Our final result is a 2{sigma} upper limit of 0.64 for the geometric albedo of HAT-P-1b between 577 and 947 nm.

  4. Surface Photometry of the Southern Milky Way at 170 NM

    NASA Astrophysics Data System (ADS)

    Hansen, J.; Schlosser, W.; Schmidtobreick, L.; Koczet, P.

    As part of the D2-Space-Shuttle-Mission in 1993, the GAUSS-Camera has obtained photographic images of the Milky Way in various passbands in the Ultraviolet. Each film covers an area of the sky of about 140^\\circ. Six images were obtained at 170 nm, but only three of them could be used. The calibration has been done using the catalogued intensities of stars and transforming them into surface brightnesses. Then the stars on the images have been filtered out and the Shuttle-Glow has been eliminated. The images finally have been transformed into maps of the Milky Way in galactic coordinates l, b. These maps cover the Milky Way between the Galactic Center and Vela (360^\\circ <= l <= 270^\\circ, - -25^\\circ <= b <= 35^\\circ) and include dark clouds, reflection nebulae and bright open clusters. They are a perfect tool to investigate the distribution of these objects and therefore the global structure of the Milky Way. The image of the Milky Way at 170 nm is heavily dominated by interstellar extinction, leading to high intensity gradients all over the galactic plane. The images at 217 nm and 280 nm, also obtained by the GAUSS-Camera, and previous photometries taken in U, B, V and R have been used for comparison.

  5. Photometry of dark atmosphereless planetary bodies: an efficient numerical model

    NASA Astrophysics Data System (ADS)

    Wilkman, Olli; Muinonen, Karri; Peltoniemi, Jouni

    2015-12-01

    We present a scattering model for regolith-covered Solar System bodies. It can be used to compute the intensity of light scattered by a surface consisting of packed, mutually shadowing particles. Our intention is to provide a model in which other researchers can apply in studies of Solar System photometry. Our model is a Lommel-Seeliger type model, representing a medium composed of individual scatterers with small single-scattering albedo. This means that it is suitable for dark regolith surfaces such as the Moon and many classes of asteroids. Our model adds an additional term which takes into account the mutual shadowing between the scatterers. The scatterers can have an arbitrary phase function. We use a numerical ray-tracing simulation to compute the shadowing contribution. We present the model in a form which makes implementing it in existing software straightforward and fast. The model in practice is implemented as files containing pre-computed values of the surface reflection coefficient, which can be loaded into a user's program and used to compute the scattering in the desired viewing geometries. As the usage requires only a little simple arithmetic and a table look-up, it is as fast to use as common analytical models.

  6. Short-period Stellar Activity Cycles with Kepler Photometry

    NASA Astrophysics Data System (ADS)

    Arkhypov, Oleksiy V.; Khodachenko, Maxim L.; Lammer, Helmut; Güdel, Manuel; Lüftinger, Theresa; Johnstone, Colin P.

    2015-07-01

    We study the short-periodic component of stellar activity with a cycle period of {P}{cyc}\\lt {10}3 days using the Kepler mission photometry of fast-rotating (1\\lt P\\lt 4 days) stars with spectra of M4V to F3V. Applying the originally developed two non-spectral methods, we measured the effective period of stellar cycles in 462 objects. The obtained results are in accordance with previous measurements by Vida et al. and do not seem to result from a beating effect. The performed measurements of Pcyc cluster in a specific branch that covers the previously unstudied region in the Saar & Brandenburg diagram and connects the branch of inactive stars with the area populated by super-active objects. It is shown that the formation of the discovered branch is due to the α-quenching effect, which saturates the magnetic dynamo and decreases the cycle periods with the increase of the inverted Rossby number. This finding is important in the context of the discussion on catastrophic quenching and other heuristic approximations of the nonlinear α-effect.

  7. Photometry and Astrometry of the Jovian satellites Amalthea and Thebe

    NASA Astrophysics Data System (ADS)

    Saquet, Eléonore; Emelyanov, Nicolai; Colas, François; Robert, Vincent; Arlot, Jean-Eudes

    2016-10-01

    During the 2014-2015 campaign of mutual events, we realized ground-based observations of Amalthea (JV) and Thebe (JXIV). We recorded two eclipses of Amalthea and, for the first time, one of Thebe by the Galilean moons. We used the 1-m telescope at Pic du Midi Observatory with an IR filter and a mask placed over the planetary image to reduce the light intensity of Jupiter. A third observation of Amalthea was taken at Saint-Sulpice Observatory with a 60-cm telescope using a methane filter (890 nm) and a deep absorption band to decrease the contrast between the planet and the satellites. We provide astrometric results derived from the photometry with an overall accuracy of 34 mas, or 100 km at Jupiter.In the same time, we realized 45 astrometric observations of Amalthea and 41 of Thebe to compare the photometric technique with direct astrometry, using the UCAC4 reference star catalog. We provide astrometric results with an overall accuracy of 100 mas for Amalthea, or 300 km at Jupiter, and 90 mas for Thebe, or 270 km at Jupiter. These results are better than those from previous ground-based and old reduced space measurements.

  8. Restoration and Photometry of Full-Disk Solar Images

    NASA Astrophysics Data System (ADS)

    Walton, Stephen R.; Preminger, Dora G.

    1999-04-01

    Daily, photometric, full-disk digital solar images have been taken at the San Fernando Observatory (SFO) in several wavelengths for more than 10 years. This work describes a project to evaluate and remove the effects of scattered light from the images, while preserving the photometry. We model both the solar limb and the point-spread function analytically, and the algorithm uses a least-squares fitting technique that does not require artificial extension of the data. Image restoration is carried out using standard techniques, with the exception of a method for estimating a non-white noise component. We show using artificial solar images with ``sunspots'' and ``faculae'' that the effects of blurring are greater near the solar limb, but that the restorations recover most of the actual contrast of surface features. Images taken with two different telescopes, after restoration, show surface feature contrasts that are in better agreement than before the restoration. In addition, the measured umbral contrast of approximately -90% on restored images at 6723 Å is the expected contrast value for umbral temperatures near 3000 K. Modeling of the solar irradiance using restored images instead of the original images from a 3 month period in 1988 shows no advantage if we use variations in sunspot deficit and facular excess to model irradiance variations. However, a new parameter, the model total irradiance derived from restored broadband red images, can model the actual solar irradiance during this period with an R2 value of 0.96.

  9. Infrared photometry of the black hole candidate Sagittarius A*

    NASA Technical Reports Server (NTRS)

    Close, Laird M.; Mccarthy, Donald W. JR.; Melia, Fulvio

    1995-01-01

    An infrared source has been imaged within 0.2 +/- 0.3 arcseconds of the unique Galactic center radio source Sgr A* High angular resolution (averaged value of the Full Width at Half Maximum (FWHM) approximately 0.55 arcseconds) was achieved by rapid (approximately 50 Hz) real-time images motion compensation. The source's near-infrared magnitudes (K = 12.1 +/- 0.3, H = 13.7 +/- 0.3, and J = 16.6 +/- 0.4) are consistent with a hot object reddened by the local extinction A(sub v) approximately 27). At the 3 sigma level of confidence, a time series of 80 images limits the source variability to less than 50% on timescales from 3 to 30 minutes. The photometry is consistent with the emission from a simple accretion disk model for a approximately 1 x 10(exp 6) solar mass black hole. However, the fluxes are also consistent with a hot luminous (L approximately 10(exp 3.5) to 10(exp 4-6) solar luminosity) central cluster star positionally coincident with Sgr A*.

  10. Analysis of RGU Photometry in Selected Area 51

    NASA Astrophysics Data System (ADS)

    Bilir, S.; Karaali, S.; Buser, R.

    2004-09-01

    A low-latitude anticenter field (l=189 °, b=+21 °) is investigated by using the full calibration tools of RGU photometry. The observed RGU data are reduced to the standard system and the separation of dwarfs and evolved stars is carried out by an empirical method. Stars are categorized into three metallicity classes, i.e. -0.25<[M/H]≤+0.50, $-1.00<[M/H]≤-0.25, and [M/H]≤-1.00 dex, and their absolute magnitudes are determined by the corresponding color-magnitude diagrams. The unusually large scattering in the two-color diagrams is reduced by excluding 153 extra-galactic objects, identifying them compared with the charts of Basel Astronomical Institute and University of Minnesota, and by the criterion and algorithm of Gaidos et al. [1]. The local logarithmic space density for giants, D*(0)=6.75, lies within the local densities of Gliese and Gliese & Jahreiss. The local luminosity function in our work for the absolute magnitude interval 3

  11. SYNMAG PHOTOMETRY: A FAST TOOL FOR CATALOG-LEVEL MATCHED COLORS OF EXTENDED SOURCES

    SciTech Connect

    Bundy, Kevin; Yasuda, Naoki; Hogg, David W.; Higgs, Tim D.; Nichol, Robert C.; Masters, Karen L.; Lang, Dustin; Wake, David A.

    2012-12-01

    Obtaining reliable, matched photometry for galaxies imaged by different observatories represents a key challenge in the era of wide-field surveys spanning more than several hundred square degrees. Methods such as flux fitting, profile fitting, and PSF homogenization followed by matched-aperture photometry are all computationally expensive. We present an alternative solution called 'synthetic aperture photometry' that exploits galaxy profile fits in one band to efficiently model the observed, point-spread-function-convolved light profile in other bands and predict the flux in arbitrarily sized apertures. Because aperture magnitudes are the most widely tabulated flux measurements in survey catalogs, producing synthetic aperture magnitudes (SYNMAGs) enables very fast matched photometry at the catalog level, without reprocessing imaging data. We make our code public and apply it to obtain matched photometry between Sloan Digital Sky Survey ugriz and UKIDSS YJHK imaging, recovering red-sequence colors and photometric redshifts with a scatter and accuracy as good as if not better than FWHM-homogenized photometry from the GAMA Survey. Finally, we list some specific measurements that upcoming surveys could make available to facilitate and ease the use of SYNMAGs.

  12. Photometric Study of IC 2156

    NASA Astrophysics Data System (ADS)

    Tadross, A. L.; Hendy, Y. H. M.

    2016-04-01

    We present an optical UBVRI photometric analysis of the poorly studied open star cluster IC 2156 using Sloan Digital Sky Survey data in order to estimate its astrophysical properties. We compare these with results from our previous studies that relied on the 2MASS JHK near-infrared photometry. The stellar density distributions and color-magnitude diagrams of the cluster are used to determine its geometrical structure, real radius, core and tidal radii, and its distance from the Sun, the Galactic plane, and the Galactic center. We also estimate, the age, color excesses, reddening-free distance modulus, membership, total mass, luminosity function, mass function, and relaxation time of the cluster.

  13. Vinculación entre varios cúmulos estelares y estructuras del medio interestelar

    NASA Astrophysics Data System (ADS)

    Corti, M. A.; Baume, G. L.; Panei, J. A.; Suad, L. A.; Testori, J. C.; Borissova, J.; Kurtev, R.; Chené, A. N.; Ramirez Alegría, S.

    2015-08-01

    We study the embedded clusters DBS77, 78, 102, 160, and 161 located in the Galactic plane in the fourth quadrant of the Milky Way and the surrounding interstellar medium (ISM). We analyzed UBVIc photometry (SOAR) and infrared spectroscopy (NTT, ESO). We complemented these data with JHK (VVV2MASS), HI 21 cm bands (SGPS), 1.4 GHz (ATCA), and 4.85 GHz (PMN). We did multiband analysis and spectral classification of the brightest stars in each area. We also identified the ISM structures possibly related to the clusters. Finally, we obtained the main parameters of the studied clusters, the structures of the ISM and the link between them.

  14. L-band (3.5 μm) IR-excess in massive star formation. I. 30 Doradus

    NASA Astrophysics Data System (ADS)

    Maercker, M.; Burton, M. G.

    2005-08-01

    L-band data of 30 Doradus at 3.5 μm taken with SPIREX (South Pole Infrared Explorer) is presented. The photometry was combined with 2MASS JHK data at 1.25-2.2 μm. Colour-colour and colour-magnitude diagrams are constructed and used to determine the sources with infrared excess. These are interpreted as circumstellar disks, and enable the fraction of sources with disks (the cluster disk fraction or CDF) to be determined. We find that ~42% of the sources detected at L-band in 30 Doradus have an IR-excess.

  15. 2MASS J06164006-6407194: THE FIRST OUTER HALO L SUBDWARF

    SciTech Connect

    Cushing, Michael C.; Looper, Dagny; Burgasser, Adam J.; Sanderson, Robyn E.; Kirkpatrick, J. Davy; Cruz, Kelle L.; Sweet, Anne

    2009-05-01

    We present the serendipitous discovery of an L subdwarf in the Two Micron All Sky Survey (2MASS) J06164006-6407194, in a search of the 2MASS for T dwarfs. Its spectrum exhibits features indicative of both a cool and metal poor atmosphere including a heavily pressure-broadened K I resonant doublet, Cs I and Rb I lines, molecular bands of CaH, TiO, CrH, FeH, and H{sub 2}O, and enhanced collision induced absorption of H{sub 2}. We assign 2MASS J0616-6407 a spectral type of sdL5 based on a comparison of its red optical spectrum to that of near solar-metallicity L dwarfs. Its high proper motion ({mu} = 1.''405 {+-} 0.008 yr{sup -1}), large radial velocity (V {sub rad} = 454 {+-} 15 km s{sup -1}), estimated u, v, w velocities (94, -573, 125) km s{sup -1} and Galactic orbit with an apogalacticon at {approx}29 kpc are indicative of membership in the outer halo making 2MASS J0616-6407 the first ultracool member of this population.

  16. The RSA survey of dwarf galaxies, 1: Optical photometry

    NASA Technical Reports Server (NTRS)

    Vader, J. Patricia; Chaboyer, Brian

    1994-01-01

    We present detailed surface photometry, based on broad B-band charge coupled device (CCD) images, of about 80 dwarf galaxies. Our sample represents approximately 10% of all dwarf galaxies identified in the vicinity of Revised Shapley-Ames (RSA) galaxies on high resolution blue photographic plates, referred to as the RSA survey of dwarf galaxies. We derive global properties and radial surface brightness profiles, and examine the morphologies. The radial surface brightness profiles of dwarf galaxies, whether early or late type, display the same varieties in shape and complexity as those of classical giant galaxies. Only a few are well described by a pure r(exp 1/4) law. Exponential profiles prevail. Features typical of giant disk galaxies, such as exponential profiles with a central depression, lenses, and even, in one case (IC 2041), a relatively prominent bulge are also found in dwarf galaxies. Our data suggest that the central region evolves from being bulge-like, with an r(exp 1/4) law profile, in bright galaxies to a lens-like structure in dwarf galaxies. We prove detailed surface photometry to be a helpful if not always sufficient tool in investigating the structure of dwarf galaxies. In many cases kinematic information is needed to complete the picture. We find the shapes of the surface brightness profiles to be loosely associated with morphological type. Our sample contains several new galaxies with properties intermediate between those of giant and dwarf ellipticals (but no M32-like objects). This shows that such intermediate galaxies exist so that at least a fraction of early-type dwarf ellipticals is structurally related to early-type giants instead of belonging to a totally unrelated, disjunct family. This supports an origin of early-type dwarf galaxies as originally more massive systems that acquired their current morphology as a result of substantial, presumable supernova-driven, mass loss. On the other hand, several early-type dwarfs in our sample are

  17. Monitoring of brain potassium with rubidium flame photometry and MRI.

    PubMed

    Yushmanov, Victor E; Kharlamov, Alexander; Boada, Fernando E; Jones, Stephen C

    2007-03-01

    An animal model was developed to monitor [K(+)] in the brain using partial K(+) replacement with Rb(+) and (87)Rb MRI. Fifty-one rats were given 0-80 mM of RbCl in the drinking water for up to 90 days. Focal cerebral ischemia was produced in 15 of the animals. Na, K, and Rb content in precision-guided submilligram samples of cortical brain were determined by emission flame photometry. Multinuclear (87)Rb/(23)Na/(1)H MRI was performed on phantoms and rats at 3T using a twisted projection imaging (TPI) scheme for (87)Rb/(23)Na, and custom-built surface or parallel cosine transmit/receive coils. Brain [Rb(+)] was safely brought up to 17-25 mEq/kg within 2-3 weeks of feeding. The characteristic patterns of [K(+)] decrease (with a sharp drop at 3-4 hr of ischemia) and [Na(+)] increase (at a rate of 31%/hr) observed previously in animals without Rb/K substitution were reproduced in ischemic cortex. The Rb/(Rb+K) ratio increased over time in ischemic areas (R = 0.91, P < 0.001), suggesting an additional index of ischemia progression. Preliminary (87)Rb MRI gave an estimate of 20-25 mEq Rb/kg brain weight (N = 2). In conclusion, brain Rb(+) is detectable by (87)Rb MRI and does not significantly interfere with ion dynamics in ischemic brain, which enables (87)Rb MRI studies of K(+) in ischemia.

  18. Just the Photometry: Constraining exoplanet orbits by measuring stellar densities

    NASA Astrophysics Data System (ADS)

    Sliski, David; Kipping, D. M.

    2014-01-01

    One unique trick in toolkit of astronomers studying transiting exoplanets, is that the mean stellar density may be determined using the shape of the light curve, under various idealized assumptions such as a circular orbit and the target star is unblended. “Asterodensity profiling” seeks to exploit this trick by comparing the light curve derived stellar density to that from some independent measurement. Any difference between the two measures indicates that one or more of the idealized assumptions are invalid. Therefore, the major challenge with single-planet systems (so-called “single-body asterodensity profiling” or SAP) is distinguishing whether the difference is due to a blend, orbital eccentricity or some combination. By careful consideration of the input priors, utilizing constraints from secondary eclipses and a Bayesian analysis of the system in question, the problem is tractable though, offering the chance to determine the underlying eccentricity distribution of exoplanets and even aid in validating planet candidates through blend analysis. In this talk, I will discuss single-body asterodensity profiling (SAP) for targets with asteroseismologically determined stellar densities, which is generally considered a gold-standard measure. We have investigated several targets with the largest apparent discrepancies between the transit-derived stellar density and that from asteroseismology. By independently detrending and fitting the transit light curves, we have calculated a revised value of this crucial ratio, with various priors tried. I will present the current results our work and discuss implications for the eccentricity and blend validation of these studied systems. I will finish by exploring the exciting potential of this technique in the TESS-era, where the fact our technique requires bright-star photometry alone, opens the door to constraints for hundreds/thousands of objects.

  19. BATC 15 Band Photometry of the Open Cluster NGC 188

    NASA Astrophysics Data System (ADS)

    Wang, Jiaxin; Ma, Jun; Wu, Zhenyu; Wang, Song; Zhou, Xu

    2015-08-01

    This paper presents CCD multicolor photometry for the old open cluster NGC 188. The observations were carried out as part of the Beijing-Arizona-Taiwan-Connecticut Multicolor Sky Survey from 1995 February to 2008 March, using 15 intermediate-band filters covering 3000-10000 Å. By fitting the Padova theoretical isochrones to our data, the fundamental parameters of this cluster are derived: an age of t=7.5+/- 0.5 Gyr, a distance modulus of {(m-M)}0=11.17+/- 0.08, and a reddening of E(B-V)=0.036+/- 0.010. The radial surface density profile of NGC 188 is obtained using the star count. By fitting the King model, the structural parameters of NGC 188 are derived: a core radius of {R}c=3\\buildrel{ \\prime}\\over{.} 80, a tidal radius of {R}t=44\\buildrel{ \\prime}\\over{.} 78, and a concentration parameter of {C}0={log}({R}t/{R}c)=1.07. Fitting the mass function (MF) to a power-law function φ (m)\\propto {m}α , the slopes of the MFs for different spatial regions are derived. We find that NGC 188 presents a slope break in the MF. The break mass is {m}{break}=0.885 {M}⊙ . In the mass range above {m}{break}, the slope of the overall region is α =-0.76. The slope of the core region is α =1.09, and the slopes of the external regions are α =-0.86 and α =-2.15, respectively. In the mass range below {m}{break}, these slopes are α =0.12, α =4.91, α =1.33, and α =-1.09, respectively. The mass segregation in NGC 188 is reflected in the obvious variation of the slopes in different spatial regions of this cluster.

  20. A Remotely Operated Observatory for Minor Planet Photometry

    NASA Astrophysics Data System (ADS)

    Ditteon, Richard

    2008-05-01

    In October of 2007 Rose-Hulman Institute of Technology in Terre Haute, Indiana began operating the Oakley Southern Sky Observatory (E09) located near Siding Spring Observatory in New South Wales, Australia. The observatory houses a 0.5-m, f/8.4 Ritchey-Chretien telescope mounted on a Paramount ME, German equatorial mount. Attached to the telescope is an STL-1001E CCD camera which has 1024 by 1024, 24 µm pixels, a two-stage thermoelectric cooler, and built in color filter wheel with BVRI and clear filters. Image scale is 1.2 arcseconds per pixel. A cloud sensor is used to monitor sky conditions. The observatory has a roll-off roof with limit switches to detect when the roof is fully open and fully closed. In addition, a switch has been added to the mount to detect when the telescope is parked and that it is safe to open or close the roof. All of the hardware is controlled by a custom program which reads a simple text file containing the sequence of images and targets to be collected each night. The text file is loaded onto the control computer once each day, then the software waits until sunset to determine if the sky is clear. When conditions are favorable, power is turned on, the roof opens, twilight flats, dark and bias frames are recorded, and when it is fully dark data frames are recorded. Images are transferred via the Internet back to Rose-Hulman by another program running in the background. The observatory closes itself before dawn or if it gets cloudy. Currently we are using the observatory for photometry of minor planets. Students are responsible for selecting targets, processing the returned images, determining the period and light curve of each minor planet and writing a paper for publication. Recent results will be presented.

  1. Spitzer/IRAC Photometry Of The Four Largest Uranian Satellites

    NASA Astrophysics Data System (ADS)

    Cartwright, Richard; Emery, J.; Rivkin, A.; Trilling, D.

    2012-10-01

    The surfaces of the four largest Uranian satellites are dominated by water ice and a spectrally neutral constituent that is likely carbonaceous in composition. CO2 ice has been detected on Ariel, Umbriel, and Titania, with no detection on the furthest regular Uranian satellite, Oberon (Grundy et al., 2003, 2006). Whether CO2 ice is primordial or is actively produced in the Uranian system is unclear; however, it seems unlikely that primordial CO2 ice would remain exposed on an icy satellite surface over the age of the Solar System. One possible mechanism for producing CO2 ice is bombardment of water ice and carbonaceous material by charged particles caught in Uranus’ magnetic field. Unlike the other large Uranian satellites, Oberon spends part of its orbit outside the confines of Uranus’ magnetic field, which might help explain why CO2 ice has yet to be detected on Oberon. We are using photometric data gathered by the Infrared Array Camera (IRAC), onboard the Spitzer Space Telescope (SST), in order to search for the signature of CO2 ice on Oberon, and confirm its presence on Ariel, Umbriel, and Titania at longer wavelengths than previous studies. IRAC collects data in four different channels, which are centered roughly at 3.6, 4.5, 5.8, and 8.0 µm. Additionally, we are gathering spectroscopic data using SpeX on IRTF, at similar longitudes to the IRAC observations, in order to characterize the distribution of CO2 ice on these icy satellites over a wide range of near-infrared wavelengths. Our preliminary photometry results for Oberon indicate that there is a steep reduction in reflected solar flux from channel 1 to channel 2, suggesting that surface materials are absorbing photons at wavelengths within the bandpass of channel 2. We will present the results of our photometric analysis of the four largest Uranian moons.

  2. Secondary Eclipse Photometry of WASP-4b with Warm Spitzer

    NASA Astrophysics Data System (ADS)

    Beerer, Ingrid M.; Knutson, Heather A.; Burrows, Adam; Fortney, Jonathan J.; Agol, Eric; Charbonneau, David; Cowan, Nicolas B.; Deming, Drake; Desert, Jean-Michel; Langton, Jonathan; Laughlin, Gregory; Lewis, Nikole K.; Showman, Adam P.

    2011-01-01

    We present photometry of the giant extrasolar planet WASP-4b at 3.6 and 4.5 μm taken with the Infrared Array Camera on board the Spitzer Space Telescope as part of Spitzer's extended warm mission. We find secondary eclipse depths of 0.319% ± 0.031% and 0.343% ± 0.027% for the 3.6 and 4.5 μm bands, respectively, and show model emission spectra and pressure-temperature profiles for the planetary atmosphere. These eclipse depths are well fit by model emission spectra with water and other molecules in absorption, similar to those used for TrES-3 and HD 189733b. Depending on our choice of model, these results indicate that this planet has either a weak dayside temperature inversion or no inversion at all. The absence of a strong thermal inversion on this highly irradiated planet is contrary to the idea that highly irradiated planets are expected to have inversions, perhaps due the presence of an unknown absorber in the upper atmosphere. This result might be explained by the modestly enhanced activity level of WASP-4b's G7V host star, which could increase the amount of UV flux received by the planet, therefore reducing the abundance of the unknown stratospheric absorber in the planetary atmosphere as suggested in Knutson et al. We also find no evidence for an offset in the timing of the secondary eclipse and place a 2σ upper limit on |ecos ω| of 0.0024, which constrains the range of tidal heating models that could explain this planet's inflated radius.

  3. Precision Photometry to Study the Nature of Dark Energy

    SciTech Connect

    Lorenzon, Wolfgang; Schubnell, Michael

    2011-01-30

    Over the past decade scientists have collected convincing evidence that the expansion of the universe is accelerating, leading to the conclusion that the content of our universe is dominated by a mysterious 'dark energy'. The fact that present theory cannot account for the dark energy has made the determination of the nature of dark energy central to the field of high energy physics. It is expected that nothing short of a revolution in our understanding of the fundamental laws of physics is required to fully understand the accelerating universe. Discovering the nature of dark energy is a very difficult task, and requires experiments that employ a combination of different observational techniques, such as type-Ia supernovae, gravitational weak lensing surveys, galaxy and galaxy cluster surveys, and baryon acoustic oscillations. A critical component of any approach to understanding the nature of dark energy is precision photometry. This report addresses just that. Most dark energy missions will require photometric calibration over a wide range of intensities using standardized stars and internal reference sources. All of the techniques proposed for these missions rely on a complete understanding of the linearity of the detectors. The technical report focuses on the investigation and characterization of 'reciprocity failure', a newly discovered count-rate dependent nonlinearity in the NICMOS cameras on the Hubble Space Telescope. In order to quantify reciprocity failure for modern astronomical detectors, we built a dedicated reciprocity test setup that produced a known amount of light on a detector, and to measured its response as a function of light intensity and wavelength.

  4. Campaign Photometry During The 2010 Eclipse Of Epsilon Aurigae

    NASA Astrophysics Data System (ADS)

    Hopkins, Jeff; Stencel, R. E.

    2011-01-01

    Epsilon Aurigae is a long period (27.1 years) eclipsing binary star system with an eclipse that lasts nearly 2 years, but with severe ambiguities about component masses and shape. The current eclipse began on schedule in August of 2009. During the previous, 1982-1984 eclipse, an International Campaign was formed to coordinate a detailed study of the system. While that Campaign was deemed successful, the evolutionary status of the star system remained unclear. Epsilon Aurigae has been observed nearly continuously since the 1982 eclipse. The current Campaign was officially started in 2006. In addition to a Yahoo forum we have a dedicated web site and more than 18 online newsletters reporting photometry, spectroscopy, interferometry and polarimetry data. High quality UBVRIJH band photometric data since before the start of the current eclipse has been submitted. We explore the color differences among the light curves in terms of eclipse phases and archival data. At least one new model of the star system has been proposed since the current Campaign began: a low mass but very high luminosity F star plus a B star surrounded by a debris disk. The current eclipse and in particular the interferometry and spectroscopic data have caused new thoughts on defining eclipsing variable star contact points and phases of an eclipse. Second contact may not be the same point as start of totality and third contact may not be the same point as the start of egress and end of totality. In addition, the much awaited mid-eclipse brightening may or may not have appeared. This paper identifies the current Campaign contributors and the photometric data. This work was supported in part by the bequest of William Herschel Womble in support of astronomy at the University of Denver, by NSF grant 1016678 to the University of Denver.

  5. Submillimeter photometry and lightcurves of Ceres and other large asteroids

    NASA Astrophysics Data System (ADS)

    Chamberlain, Matthew A.; Lovell, Amy J.; Sykes, Mark V.

    2009-08-01

    Photometry and thermal lightcurves of six large asteroids (1-Ceres, 2-Pallas, 3-Juno, 12-Victoria, 85-Io and 511-Davida) have been observed at 870 μm (345 GHz) using the MPIfR 19-Channel Bolometer of the Heinrich-Hertz Submillimeter Telescope. Only Ceres displayed a lightcurve with an amplitude (˜50%, peak to peak) that was significantly greater than the uncertainty in the observations. When thermal fluxes and brightness temperatures are corrected for heliocentric distance and albedo, there is a significant relation with the sub-solar latitude of the asteroid, or the local season of the asteroid. No such trend can be found between observations with solar phase angle. These results are evidence that most of the submillimeter thermal radiation is emitted from below the diurnal thermal wave. Comparing the observed trend with model output suggests that the submillimeter radiation from all the asteroids we observed is best modeled by surface material with low thermal inertia (<15 J m -2 s -0.5 K -1, consistent with mid-infrared observations of large main-belt asteroids) and a refractive index closer to unity relative to densities inferred from radar experiments, implying a veneer of material over the asteroid surface with a density less than 1000 kg m -3. More data with better signal-to-noise and aspect coverage could improve these models and constrain physical properties of asteroid surface materials. This would also allow asteroids to be used as calibration sources with accurately known and stable, broadband fluxes at long wavelengths.

  6. VizieR Online Data Catalog: Photometry and motions in Arches and Quintuplet (Stolte+, 2015)

    NASA Astrophysics Data System (ADS)

    Stolte, A.; Hussmann, B.; Olczak, C.; Brandner, W.; Habibi, M.; Ghez, A. M.; Morris, M. R.; Lu, J., R.; Clarkson, W., I.; Anderson, J.

    2015-02-01

    Two to three epochs of photometry and astrometric imaging were obtained in the Arches and Quintuplet clusters with the VLT/NAOS-CONICA instrument from 2002 to 2012, covering timebaselines from 3 to 5 years in each of five fields per cluster. Astrometry and proper motions were derived from Ks imaging. The combination with HST/WFC3 F127M and F153M imaging provided infrared colours, and NACO L' observations were used to derive infrared excess emission. The spatial resolution of all NAOS-CONICA observations was 27.1-milliarcseconds/pixel and 130mas/pixel for all WFC3 images. The catalogue provides all epochs of Ks photometry and proper motions for stars brighter than Ks=17.5mag. Proper motions are derived as the positional difference between two astrometric epochs. HST/WFC3 F127M and F153M photometry was converted to standard JH photometry with colour equations provided in the paper. L' photometry was referenced to the Spitzer/GLIMPSE survey with uncertain zeropoints due to the large differences in spatial resolution, and absolute values should be treated with care, while relative photometry is robust. Membership indicators are given as follows: 1: likely cluster member, 0: likely non-member, -1: unknown membership, -99: two epoch measurements could not be obtained. For Quintuplet cluster (tablee1.dat), an indication of cluster membership is given as a formal probability in Field 2-5, where stars with pclus>0.4 are likely member candidates. A value of -99.0 indicates that the corresponding photometry or astrometry could not be obtained. (2 data files).

  7. Laser flare photometry: a noninvasive, objective, and quantitative method to measure intraocular inflammation.

    PubMed

    Tugal-Tutkun, Ilknur; Herbort, Carl P

    2010-10-01

    Aqueous flare and cells are the two inflammatory parameters of anterior chamber inflammation resulting from disruption of the blood-ocular barriers. When examined with the slit lamp, measurement of intraocular inflammation remains subjective with considerable intra- and interobserver variations. Laser flare cell photometry is an objective quantitative method that enables accurate measurement of these parameters with very high reproducibility. Laser flare photometry allows detection of subclinical alterations in the blood-ocular barriers, identifying subtle pathological changes that could not have been recorded otherwise. With the use of this method, it has been possible to compare the effect of different surgical techniques, surgical adjuncts, and anti-inflammatory medications on intraocular inflammation. Clinical studies of uveitis patients have shown that flare measurements by laser flare photometry allowed precise monitoring of well-defined uveitic entities and prediction of disease relapse. Relationships of laser flare photometry values with complications of uveitis and visual loss further indicate that flare measurement by laser flare photometry should be included in the routine follow-up of patients with uveitis.

  8. Hot Subdwarf Stars Among the Objects Rejected from the PG Catalog: a First Assessment Using GALEX Photometry

    NASA Technical Reports Server (NTRS)

    Wade, Richard A.; Stark, M. A.; Green, Richard F.; Durrell, Patrick R.

    2009-01-01

    The hot subdwarf (sd) stars in the Palomar Green (PG) catalog of ultraviolet excess (UVX) objects play a key role in investigations of the frequency and types of binary companions and the distribution of orbital periods. These are important for establishing whether and by which channels the sd stars arise from interactions in close binary systems. It has been suggested that the list of PG sd stars is biased by the exclusion of many stars in binaries, whose spectra show the Ca I1 K line in absorption. A total of 1125 objects that were photometrically selected as candidates were ultimately rejected from the final PG catalog using this K-line criterion. We study 88 of these 'PG-Rejects' (PGRs), to assess whether there are significant numbers of unrecognized sd stars in binaries among the PGR objects. The presence of a sd should cause a large UVX, compared with the cool K-line star. We assemble GALEX, Johnson V, and 2MASS photometry and compare the colors of these PGR objects with those of known sd stars, cool single stars, and hot+cool binaries. Sixteen PGRs were detected in both the far- and near-ultraviolet GALEX passbands. Eleven of these, plus the 72 cases with only an upper limit in the far-ultraviolet band, are interpreted as single cool stars, appropriately rejected by the PG spectroscopy. Of the remaining five stars, three are consistent with being sd stars paired with a cool main sequence companion, while two may be single stars or composite systems of another type. We discuss the implications of these findings for the 1125 PGR objects as a whole. An enlarged study is desirable to increase confidence in these first results and to identify individual sd+cool binaries or other composites for follow-up study. The GALEX AIS data have sufficient sensitivity to carry out this larger study.

  9. Disk-resolved photometry of Asteroid (2867) Steins

    NASA Astrophysics Data System (ADS)

    Spjuth, S.; Jorda, L.; Lamy, P. L.; Keller, H. U.; Li, J.-Y.

    2012-11-01

    We present a new method to perform disk-resolved photometry in order to investigate the intrinsic photometric properties of the surface of small Solar System bodies. We adopt the standard approach where a shape model is combined with a photometric formalism - in practise the Hapke formalism - to remove the effects of topography and recover the photometric (Hapke) parameters of either the global surface or, in its most elaborated form, the spatial variations of these parameters across the surface. Our method operates in the space of the facets representing the three-dimensional shape of the body, whereas all past analysis have always been performed in the space of the image pixels although they are not intrinsic to the surface of the body. This has the advantage of automatically tracking the same local surface element on a series of images. We first apply our method to images of the nucleus of Comet 9P/Tempel 1 obtained by the High-Resolution Imager (HRI) instrument on board the Deep Impact spacecraft and our derived Hapke parameters are in good agreement with those published by Li et al. (Li, J.-Y. et al. [2007]. Icarus 187, 41-55) within their respective uncertainties. We confirm the presence of an extended region of higher roughness in the southern hemisphere of the nucleus and the higher albedo of the ice-rich regions identified by Sunshine et al. (Sunshine, J.M. et al. [2006]. Science 311, 1453-1455) near the equator. The photometric properties of Asteroid (2867) Steins are then studied from multi-spectral images obtained with the OSIRIS Wide Angle Camera (WAC) on board the Rosetta spacecraft during its flyby on 5 September 2008. Our analysis indicates that the surface is highly porous (∼84%) and that it exhibits both a shadow-hiding opposition effect (SHOE) and probably, a coherent-backscatter opposition effect (CBOE). The single scattering albedo is the highest (SSA = 0.57) ever observed among small bodies visited by spacecrafts. Our modelled roughness

  10. Surface photometry of galaxies in low density regions.

    NASA Astrophysics Data System (ADS)

    Vennik, J.; Hopp, U.; Kovachev, B.; Kuhn, B.; Elsaesser, H.

    1996-06-01

    We perform detailed surface photometry, based on B- and/or R-band CCD images of 92 faint galaxies. They are a subsample of those galaxies which were studied by Hopp et al. (1994) in the direction of three nearby voids. We derive integral photometric parameters and radial surface brightness profiles and compare them to those of several faint galaxy samples, located in different environments, and of a bright field galaxy sample. According to the obtained photometric characteristics, our sample is a mixture of intrinsically bright and faint galaxies, about 60% of them belonging to the bright subsample (M_B_<-19.0). These bright ones show mean characteristics of typical Freeman's disks and are mainly located in the background of the observed voids. The faint subsample (M_B_>=-19.0) has parameters typical for the low-surface-brightness (LSB) galaxies. There are a few well isolated galaxies both among the bright and faint subsamples. About 40% of studied galaxies reveal ellipticity and position angle variations along of the radius. The (B-R) colour indices of the observed galaxies span over a wide range of 0.5-1.8mag with a median value at 1.11 mag, rather blue. About 30% of the observed galaxies reveal radial colour gradients at a 5σ significance level. These galaxies show typically red centers and are getting bluer towards the periphery. The most isolated galaxies in our sample show relatively blue colours (B_T_-R_T_=~0.8). About 40% of the studied galaxies have surface brightness profiles which can be described by the model of single exponential disk. 38% of our galaxies have more complicated profiles and either can be approximated by two exponentials or show the presence of a small bulge. 20% of the observed galaxies have central light depression and outer irregularities - typical for some dwarf galaxies. These profile type frequencies are similar to those of faint field galaxy sample. The evolutionary history of both the isolated and clustered galaxies obviously

  11. Deep Intermediate-Band Surface Photometry of NGC 5907

    NASA Astrophysics Data System (ADS)

    Zheng, Zhongyuan; Shang, Zhaohui; Su, Hongjun; Burstein, David; Chen, Jiansheng; Deng, Zugan; Byun, Yong-Ik; Chen, Rui; Chen, Wen-Ping; Deng, Licai; Fan, Xiaohui; Fang, Li-Zhi; Hester, J. Jeff; Jiang, Zhaoji; Li, Yong; Lin, Weipeng; Sun, Wei-Hsin; Tsay, Wean-Shun; Windhorst, Rogier A.; Wu, Hong; Xia, Xiaoyang; Xu, Wen; Xue, Suijian; Yan, Haojing; Zheng, Zheng; Zhou, Xu; Zhu, Jin; Zou, Zhenglong; Lu, Phillip

    1999-06-01

    Intrigued by the initial report of an extended luminosity distribution perpendicular to the disk of the edge-on Sc galaxy NGC 5907, we have obtained very deep exposures of this galaxy with a Schmidt telescope, large-format CCD, and intermediate-band filters centered at 6660 Å and 8020 Å. These two filters, part of a 15-filter set, are custom designed to avoid the brightest (and most variable) night skylines. As a result, our images are able to go deeper with lower sky noise than those taken with broadband filters at similar effective wavelengths: e.g., 0.6 e^- arcsec^-2 s^-1 for our observations versus 7.4 e^- arcsec^-2 s^-1 for the R-band measures of Morrison et al. In our assessment of both random and systematic errors, we show that the flux level where the errors of observation reach 1 mag arcsec^-2 are 29.00 mag arcsec^-2 in the 6660 Å image (corresponding to 28.7 in the R band) and 27.4 mag arcsec^-2 in the 8020 Å image (essentially on the I-band system). In a previous paper we have shown that NGC 5907 has a luminous ring around it, most plausibly caused by the tidal disruption of a dwarf spheroidal galaxy by the much more massive spiral. Here we show that, for values fainter than 27 R mag arcsec^-2, the surface brightness around NGC 5907 is strongly asymmetric, being mostly brighter on the northwest (ring) side of the galactic midplane. This asymmetry rules out a halo as the cause of the faint surface brightness we see. We find this asymmetry is likely an artifact resulting from a combination of ring light and residual surface brightness at faint levels from stars that our star-masking procedure cannot completely eliminate. The possible existence of an optical face-on warp in NGC 5907, suggested by our Very Large Array H I observations, is too confused with foreground star contamination to be independently studied. Good agreement with the surface photometry of NGC 5907 by other observers leads us to conclude that their data are similarly affected at faint

  12. Absolute parameters for AI Phoenicis using WASP photometry

    NASA Astrophysics Data System (ADS)

    Kirkby-Kent, J. A.; Maxted, P. F. L.; Serenelli, A. M.; Turner, O. D.; Evans, D. F.; Anderson, D. R.; Hellier, C.; West, R. G.

    2016-06-01

    Context. AI Phe is a double-lined, detached eclipsing binary, in which a K-type sub-giant star totally eclipses its main-sequence companion every 24.6 days. This configuration makes AI Phe ideal for testing stellar evolutionary models. Difficulties in obtaining a complete lightcurve mean the precision of existing radii measurements could be improved. Aims: Our aim is to improve the precision of the radius measurements for the stars in AI Phe using high-precision photometry from the Wide Angle Search for Planets (WASP), and use these improved radius measurements together with estimates of the masses, temperatures and composition of the stars to place constraints on the mixing length, helium abundance and age of the system. Methods: A best-fit ebop model is used to obtain lightcurve parameters, with their standard errors calculated using a prayer-bead algorithm. These were combined with previously published spectroscopic orbit results, to obtain masses and radii. A Bayesian method is used to estimate the age of the system for model grids with different mixing lengths and helium abundances. Results: The radii are found to be R1 = 1.835 ± 0.014 R⊙, R2 = 2.912 ± 0.014 R⊙ and the masses M1 = 1.1973 ± 0.0037 M⊙, M2 = 1.2473 ± 0.0039 M⊙. From the best-fit stellar models we infer a mixing length of 1.78, a helium abundance of YAI = 0.26 +0.02-0.01 and an age of 4.39 ± 0.32 Gyr. Times of primary minimum show the period of AI Phe is not constant. Currently, there are insufficient data to determine the cause of this variation. Conclusions: Improved precision in the masses and radii have improved the age estimate, and allowed the mixing length and helium abundance to be constrained. The eccentricity is now the largest source of uncertainty in calculating the masses. Further work is needed to characterise the orbit of AI Phe. Obtaining more binaries with parameters measured to a similar level of precision would allow us to test for relationships between helium

  13. MOST photometry of the roAp star 10 Aquilae

    NASA Astrophysics Data System (ADS)

    Huber, D.; Saio, H.; Gruberbauer, M.; Weiss, W. W.; Rowe, J. F.; Hareter, M.; Kallinger, T.; Reegen, P.; Matthews, J. M.; Kuschnig, R.; Guenther, D. B.; Moffat, A. F. J.; Rucinski, S.; Sasselov, D.; Walker, G. A. H.

    2008-05-01

    Context: We present 31.2 days of nearly continuous MOST photometry of the rapidly oscillating Ap star 10 Aql. Aims: The goal was to provide an unambiguous frequency identification for this little studied star, as well as to discuss the detected frequencies in the context of magnetic models and analyze the influence of the magnetic field on the pulsation. Methods: Using traditional Fourier analysis techniques on three independent data reductions, intrinsic frequencies for the star are identified. Theoretical non-adiabatic axisymmetric modes influenced by a magnetic field having polar field strengths BP = 0-5 kG were computed to compare the observations to theory. Results: The high-precision data allow us to identify three definite intrinsic pulsation frequencies and two other candidate frequencies with low S/N. Considering the observed spacings, only one (Δν = 50.95 μHz) is consistent with the main sequence nature of roAp stars. The comparison with theoretical models yields a best fit for a 1.95 M⊙ model having solar metallicity, suppressed envelope convection, and homogenous helium abundance. Furthermore, our analysis confirms the suspected slow rotation of the star and sets new lower limits to the rotation period (P_rot≥ 1 month) and inclination (i>30±10°). Conclusions: The observed frequency spectrum is not rich enough to unambiguously identify a model. On the other hand, the models hardly represent roAp stars in detail due to the approximations needed to describe the interactions of the magnetic field with stellar structure and pulsation. Consequently, errors in the model frequencies needed for the fitting procedure can only be estimated. Nevertheless, it is encouraging that models which suppress convection and include solar metallicity, in agreement with current concepts of roAp stars, fit the observations best. Based on data from the MOST satellite, a Canadian Space Agency mission, jointly operated by Dynacon Inc., the University of Toronto Institute

  14. Near-infrared Variability in the 2MASS Calibration Fields: A Search for Planetary Transit Candidates

    NASA Technical Reports Server (NTRS)

    Plavchan, Peter; Jura, M.; Kirkpatrick, J. Davy; Cutri, Roc M.; Gallagher, S. C.

    2008-01-01

    The Two Micron All Sky Survey (2MASS) photometric calibration observations cover approximately 6 square degrees on the sky in 35 'calibration fields,' each sampled in nominal photometric conditions between 562 and 3692 times during the 4 years of the 2MASS mission. We compile a catalog of variables from the calibration observations to search for M dwarfs transited by extrasolar planets. We present our methods for measuring periodic and nonperiodic flux variability. From 7554 sources with apparent K(sub s) magnitudes between 5.6 and 16.1, we identify 247 variables, including extragalactic variables and 23 periodic variables. We have discovered three M dwarf eclipsing systems, including two candidates for transiting extrasolar planets.

  15. 2MASS J20261584-2943124: AN UNRESOLVED L0.5 + T6 SPECTRAL BINARY

    SciTech Connect

    Gelino, Christopher R.; Burgasser, Adam J.

    2010-07-15

    We identify the L dwarf 2MASS J20261584-2943124 as an unresolved spectral binary, based on low-resolution, near-infrared spectroscopy from IRTF/SpeX. The data reveal a peculiar absorption feature at 1.6 {mu}m, previously noted in the spectra of other very low-mass spectral binaries, which likely arises from overlapping FeH and CH{sub 4} absorption bands in the blended light of an L dwarf/T dwarf pair. Spectral template matching analysis indicates component types of L0.5 and T6, with relative brightness {Delta}H = 4.2 {+-} 0.6. Laser guide star adaptive optics imaging observations with Keck/NIRC2 fail to resolve the source, indicating a maximum separation at the observing epoch of 0.''25, or a projected separation of 9 AU assuming a distance of 36 {+-} 5 pc. With an age that is likely to be relatively older ({approx}>5 Gyr) based on the system's large V{sub tan} and mass ratio arguments, the relative motion of the potentially 'massive' (0.06-0.08 M{sub sun}) components of 2MASS J2026-2943 may be detectable through radial velocity variations, like its earlier-type counterpart 2MASS J03202839-0446358 (M8+T5), providing dynamical mass measurements that span the hydrogen burning limit.

  16. Optical BVRI photometry of common proper motion F/G/K+M wide separation binaries

    SciTech Connect

    Li, Ting; Marshall, Jennifer L.; Williams, Patrick; Chavez, Joy; Lépine, Sébastien

    2014-10-01

    We present optical (BVRI) photometric measurements of a sample of 76 common proper motion wide separation main-sequence binary pairs. The pairs are composed of a F-, G-, or K-type primary star and an M-type secondary. The sample is selected from the revised NLTT catalog and the LSPM catalog. The photometry is generally precise to 0.03 mag in all bands. We separate our sample into two groups, dwarf candidates and subdwarf candidates, using the reduced proper motion diagram constructed with our improved photometry. The M subdwarf candidates in general have larger V – R colors than the M dwarf candidates at a given V – I color. This is consistent with an average metallicity difference between the two groups, as predicted by the PHOENIX/BT-Settl models. The improved photometry will be used as input into a technique to determine the metallicities of the M-type stars.

  17. Optical BVRI Photometry of Common Proper Motion F/G/K+M Wide Separation Binaries

    NASA Astrophysics Data System (ADS)

    Li, Ting; Marshall, Jennifer L.; Lépine, Sébastien; Williams, Patrick; Chavez, Joy

    2014-10-01

    We present optical (BVRI) photometric measurements of a sample of 76 common proper motion wide separation main-sequence binary pairs. The pairs are composed of a F-, G-, or K-type primary star and an M-type secondary. The sample is selected from the revised NLTT catalog and the LSPM catalog. The photometry is generally precise to 0.03 mag in all bands. We separate our sample into two groups, dwarf candidates and subdwarf candidates, using the reduced proper motion diagram constructed with our improved photometry. The M subdwarf candidates in general have larger V - R colors than the M dwarf candidates at a given V - I color. This is consistent with an average metallicity difference between the two groups, as predicted by the PHOENIX/BT-Settl models. The improved photometry will be used as input into a technique to determine the metallicities of the M-type stars.

  18. Photoelectric photometry of Comet P/Halley from Mauna Kea Observatory

    NASA Technical Reports Server (NTRS)

    Piscitelli, J. R.; Tholen, D. J.; Hammel, H. B.; Lark, N.

    1986-01-01

    A program of photoelectric photometry of comet Halley yielded 60 nights of usable photometry. The uncertainty in the photometry in all filters except OH is better than 2%. Throughout the apparition, the comet is brightest in the filters that isolated the neutral gas emission features of OH, CN, C2, and C3. The fluxes in the filters that isolated the ionic emission features of CO(+) and H2O(+) are comparable to the continuum when centered upon the optocenter, thereby making the ionic emission weak to undetectable above the continuum. The continuum colors do not appear to be a function of phase angle; therefore, the colors are probably indicative of dust grain composition and are not dominated by scattering geometry effects.

  19. Stellar photometry with the Hubble Space Telescope Wide-field/Planetary camera - A progress report

    NASA Technical Reports Server (NTRS)

    Holtzman, Jon A.; Hunter, Deidre; Groth, Edward J.; Light, Robert M.; Faber, S. M.

    1991-01-01

    The prospects for the use of the Wide-Field/Planetary Camera (WFPC) for stellar photometry are described. The large halos of the point-spread function (PSF) resulting from spherical aberration and from spatial, temporal, and color variations of the PSF are the main limitations to accurate photometry. Degradations caused by crowding are exacerbated by the halos of the PSF. An attempt is made to quantify these effects and determine the current accuracy of stellar photometry with the WFPC. In realistic cases, the brighter stars in crowded fields have 0.09 mag errors; fainter stars have larger errors depending on the degree of crowding. It is shown that measuring Cepheids in Virgo Cluster galaxies is not currently possible without inordinate increases in exposure times.

  20. ASTERIA: A CubeSat for Exoplanet Transit and Stellar Photometry

    NASA Astrophysics Data System (ADS)

    Knapp, Mary; Seager, Sara

    2015-12-01

    We present ASTERIA, a 6U CubeSat demonstrator for exoplanet transit photometry. ASTERIA, currently in development at JPL and due to be launched in mid to late 2016, is a testbed for a two-stage pointing system capable of <10 arcsecond pointing as well as active thermal control. These two features will allow ASTERIA to achieve very high photometric precision (<100 ppm) in a very small and cost effective package. ASTERIA will be used to search for transits of known RV planets as well as perform long duration, high cadence stellar photometry. The stellar photometry data will be used to study flares and stellar activity on a variety of stellar types. This presentation will focus on ASTERIA's science mission.

  1. Hypercalibration: A Pan-STARRS1-based Recalibration of the Sloan Digital Sky Survey Photometry

    NASA Astrophysics Data System (ADS)

    Finkbeiner, Douglas P.; Schlafly, Edward F.; Schlegel, David J.; Padmanabhan, Nikhil; Jurić, Mario; Burgett, William S.; Chambers, Kenneth C.; Denneau, Larry; Draper, Peter W.; Flewelling, Heather; Hodapp, Klaus W.; Kaiser, Nick; Magnier, E. A.; Metcalfe, N.; Morgan, Jeffrey S.; Price, Paul A.; Stubbs, Christopher W.; Tonry, John L.

    2016-05-01

    We present a recalibration of the Sloan Digital Sky Survey (SDSS) photometry with new flat fields and zero points derived from Pan-STARRS1. Using point-spread function (PSF) photometry of 60 million stars with 16 < r < 20, we derive a model of amplifier gain and flat-field corrections with per-run rms residuals of 3 millimagnitudes (mmag) in griz bands and 15 mmag in u band. The new photometric zero points are adjusted to leave the median in the Galactic north unchanged for compatibility with previous SDSS work. We also identify transient non-photometric periods in SDSS (“contrails”) based on photometric deviations co-temporal in SDSS bands. The recalibrated stellar PSF photometry of SDSS and PS1 has an rms difference of {9, 7, 7, 8} mmag in griz, respectively, when averaged over 15‧ regions.

  2. FAINT NEAR-ULTRAVIOLET/FAR-ULTRAVIOLET STANDARDS FROM SWIFT/UVOT, GALEX, AND SDSS PHOTOMETRY

    SciTech Connect

    Siegel, Michael H.; Hoversten, Erik A.; Roming, Peter W. A.; Brown, Peter E-mail: hoversten@astro.psu.ed E-mail: brown@astro.psu.ed

    2010-12-10

    At present, the precision of deep ultraviolet photometry is somewhat limited by the dearth of faint ultraviolet standard stars. In an effort to improve this situation, we present a uniform catalog of 11 new faint (u {approx} 17) ultraviolet standard stars. High-precision photometry of these stars has been taken from the Sloan Digital Sky Survey and Galaxy Evolution Explorer archives and combined with new data from the Swift Ultraviolet Optical Telescope to provide precise photometric measures extending from the near-infrared to the far-ultraviolet. These stars were chosen because they are known to be hot (20, 000 < T{sub eff} < 50, 000 K) DA white dwarfs with published Sloan spectra that should be photometrically stable. This careful selection allows us to compare the combined photometry and Sloan spectroscopy to models of pure hydrogen atmospheres to both constrain the underlying properties of the white dwarfs and test the ability of white dwarf models to predict the photometric measures. We find that the photometry provides good constraints on white dwarf temperatures, which demonstrates the ability of Swift/UVOT to investigate the properties of hot luminous stars. We further find that the models reproduce the photometric measures in all 11 passbands to within their systematic uncertainties. Within the limits of our photometry, we find the standard stars to be photometrically stable. This success indicates that the models can be used to calibrate additional filters to our standard system, permitting easier comparison of photometry from heterogeneous sources. The largest source of uncertainty in the model fitting is the uncertainty in the foreground reddening curve, a problem that is especially acute in the UV.

  3. Galaxy And Mass Assembly: accurate panchromatic photometry from optical priors using LAMBDAR

    NASA Astrophysics Data System (ADS)

    Wright, A. H.; Robotham, A. S. G.; Bourne, N.; Driver, S. P.; Dunne, L.; Maddox, S. J.; Alpaslan, M.; Andrews, S. K.; Bauer, A. E.; Bland-Hawthorn, J.; Brough, S.; Brown, M. J. I.; Clarke, C.; Cluver, M.; Davies, L. J. M.; Grootes, M. W.; Holwerda, B. W.; Hopkins, A. M.; Jarrett, T. H.; Kafle, P. R.; Lange, R.; Liske, J.; Loveday, J.; Moffett, A. J.; Norberg, P.; Popescu, C. C.; Smith, M.; Taylor, E. N.; Tuffs, R. J.; Wang, L.; Wilkins, S. M.

    2016-07-01

    We present the Lambda Adaptive Multi-Band Deblending Algorithm in R (LAMBDAR), a novel code for calculating matched aperture photometry across images that are neither pixel- nor PSF-matched, using prior aperture definitions derived from high-resolution optical imaging. The development of this program is motivated by the desire for consistent photometry and uncertainties across large ranges of photometric imaging, for use in calculating spectral energy distributions. We describe the program, specifically key features required for robust determination of panchromatic photometry: propagation of apertures to images with arbitrary resolution, local background estimation, aperture normalization, uncertainty determination and propagation, and object deblending. Using simulated images, we demonstrate that the program is able to recover accurate photometric measurements in both high-resolution, low-confusion, and low-resolution, high-confusion, regimes. We apply the program to the 21-band photometric data set from the Galaxy And Mass Assembly (GAMA) Panchromatic Data Release (PDR; Driver et al. 2016), which contains imaging spanning the far-UV to the far-IR. We compare photometry derived from LAMBDAR with that presented in Driver et al. (2016), finding broad agreement between the data sets. None the less, we demonstrate that the photometry from LAMBDAR is superior to that from the GAMA PDR, as determined by a reduction in the outlier rate and intrinsic scatter of colours in the LAMBDAR data set. We similarly find a decrease in the outlier rate of stellar masses and star formation rates using LAMBDAR photometry. Finally, we note an exceptional increase in the number of UV and mid-IR sources able to be constrained, which is accompanied by a significant increase in the mid-IR colour-colour parameter-space able to be explored.

  4. Optical photometry of the 1982-1984 eclipse of Epsilon Aurigae

    NASA Technical Reports Server (NTRS)

    Hopkins, J. L.

    1985-01-01

    From slightly before the 1982-1984 eclipse of Epsilon Aurigae to the present observers from around the world have been making photoelectric photometry observations of this star system. Over 2000 UBV observations have been reported as well as observations in the R, I, J, H, K, L, M, N, and Q bandpasses plus the y, b, v, and u bandpasses. Twenty nine observers from 9 countries submitted photometry data to the campaign. The data have shown many interesting features of the star system including a Cepheid-like pulsation, flare activity, mid-eclipse brightening, post egress brightening, plus other strange activity.

  5. VizieR Online Data Catalog: gr photometry of Sextans A and Sextans B (Bellazzini+, 2014)

    NASA Astrophysics Data System (ADS)

    Bellazzini, M.; Beccari, G.; Fraternali, F.; Oosterloo, T. A.; Sollima, A.; Testa, V.; Galleti, S.; Perina, S.; Faccini, M.; Cusano, F.

    2014-04-01

    The tables present deep LBT/LBC g and r photometry of the stars having image quality parameters (provided by DAOPHOTII) CHI<=2 and SHARP within magnitude-dependent contours traced to include the bulk of stellar objects. The observations were achieved on the night og 2012-02-21 with the Large Binocular Camera at the Large Binocular Telescope in binocular mode; g images were acquired with the blue arm and r images with the red arm of the telescope/camera. The astrometry and the photometry were calibrated with stars in common with SDSS-DR9 (V/139). (2 data files).

  6. Characterizing extrasolar planets with multi-color photometry

    NASA Astrophysics Data System (ADS)

    Colon, Knicole Dawn

    Over the past twenty years, nearly 800 planets have been discovered orbiting stars other than the Sun. The discovery of these extrasolar planets (or simply, exoplanets) has led to a renewed interest in planet formation and evolution, as many exoplanets have properties that are nothing like those of the planets found in the Solar System. A subset of exoplanets are known to transit, or pass in front of, their host star, which provides a unique opportunity to measure how their radius changes with wavelength. Such measurements can be used to study the atmospheres of exoplanets, since changes in the measured radius can indicate absorption of stellar photons by the exoplanet atmosphere. Finding a significant change in the radius with wavelength can also indicate that a planet candidate is not a planet at all, but is instead an eclipsing binary star composed of two stars with different temperatures and therefore colors. With over 200 confirmed transiting exoplanets and NASA's Kepler mission's recent discovery of over 2000 transiting exoplanet candidates, detailed investigations into the properties of exoplanetary atmospheres and false positive rates for planet search surveys can now be conducted. To aid these investigations, I developed a novel technique of using the Optical System for Imaging and low Resolution Integrated Spectroscopy (OSIRIS) installed on the 10.4 meter Gran Telescopio Canarias (GTC) to acquire near-simultaneous, multi-color, narrow-band photometry of exoplanet transits. I first used this technique to observe the transits of the hot-Jupiters TrES-2b and TrES-3b, from which I reached some of the best photometric precisions (0.343-0.470 mmag) achieved to date using a ground-based telescope. I subsequently used this technique to measure a ˜ 4.2% change in the apparent planetary radius of the giant exoplanet HD 80606b during transit between wavelengths that probe potassium. I hypothesize that the excess absorption is due to potassium in a high-speed wind

  7. BRITE-Constellation: Nanosatellites for precision photometry of bright stars

    NASA Astrophysics Data System (ADS)

    Weiss, W. W.; Moffat, A. F. J.; Schwarzenberg-Czerny, A.; Koudelka, O. F.; Grant, C. C.; Zee, R. E.; Kuschnig, R.; Mochnacki, St.; Rucinski, S. M.; Matthews, J. M.; Orleański, P.; Pamyatnykh, A. A.; Pigulski, A.; Alves, J.; Guedel, M.; Handler, G.; Wade, G. A.; Scholtz, A. L.; Scholtz

    2014-02-01

    BRITE-Constellation (where BRITE stands for BRIght Target Explorer) is an international nanosatellite mission to monitor photometrically, in two colours, brightness and temperature variations of stars brighter than V ~ 4, with precision and time coverage not possible from the ground. The current mission design consists of three pairs of 7 kg nanosats (hence ``Constellation'') from Austria, Canada and Poland carrying optical telescopes (3 cm aperture) and CCDs. One instrument in each pair is equipped with a blue filter; the other, a red filter. The first two nanosats (funded by Austria) are UniBRITE, designed and built by UTIAS-SFL (University of Toronto Institute for Aerospace Studies-Space Flight Laboratory) and its twin, BRITE-Austria, built by the Technical University Graz (TUG) with support of UTIAS-SFL. They were launched on 25 February 2013 by the Indian Space Agency, under contract to the Canadian Space Agency. Each BRITE instrument has a wide field of view (~ 24 degrees), so up to 15 bright stars can be observed simultaneously in 32 × 32 sub-rasters. Photometry (with reduced precision but thorough time sampling) of additional fainter targets will be possible through on-board data processing. A critical technical element of the BRITE mission is the three-axis attitude control system to stabilize a nanosat with very low inertia. The pointing stability is better than 1.5 arcminutes rms, a significant advance by UTIAS-SFL over any previous nanosatellite. BRITE-Constellation will primarily measure p- and g-mode pulsations to probe the interiors and ages of stars through asteroseismology. The BRITE sample of many of the brightest stars in the night sky is dominated by the most intrinsically luminous stars: massive stars seen at all evolutionary stages, and evolved medium-mass stars at the very end of their nuclear burning phases (cool giants and AGB stars). The Hertzsprung-Russell diagram for stars brighter than mag V=4 from which the BRITE-Constellation sample

  8. DETECTION OF RADIO EMISSION FROM THE HYPERACTIVE L DWARF 2MASS J13153094-2649513AB

    SciTech Connect

    Burgasser, Adam J.; Melis, Carl; Zauderer, B. Ashley; Berger, Edo

    2013-01-01

    We report the detection of radio emission from the unusually active L5e + T7 binary 2MASS J13153094-2649513AB made with the Australian Telescope Compact Array. Observations at 5.5 GHz reveal an unresolved source with a continuum flux of 370 {+-} 50 {mu}Jy, corresponding to a radio luminosity of L{sub rad} = {nu}L{sub {nu}} = (9 {+-} 3) Multiplication-Sign 10{sup 23} erg s{sup -1} and log{sub 10} L{sub rad}/L{sub bol} = -5.44 {+-} 0.22. No detection is made at 9.0 GHz to a 5{sigma} limit of 290 {mu}Jy, consistent with a power-law spectrum S{sub {nu}}{proportional_to}{nu}{sup -{alpha}} with {alpha} {approx}> 0.5. The emission is quiescent, with no evidence of variability or bursts over three hours of observation, and no measurable polarization (V/I < 34%). 2MASS J1315-2649AB is one of the most radio-luminous ultracool dwarfs detected in quiescent emission to date, comparable in strength to other cool sources detected in outburst. Its detection indicates no decline in radio flux through the mid-L dwarfs. It is unique among L dwarfs in having strong and persistent H{alpha} and radio emission, indicating the coexistence of a cool, neutral photosphere (low electron density) and a highly active chromosphere (high electron density and active heating). These traits, coupled with the system's mature age and substellar secondary, make 2MASS J1315-2649AB an important test for proposed radio emission mechanisms in ultracool dwarfs.

  9. Detection of Radio Emission from the Hyperactive L Dwarf 2MASS J13153094-2649513AB

    NASA Astrophysics Data System (ADS)

    Burgasser, Adam J.; Melis, Carl; Zauderer, B. Ashley; Berger, Edo

    2013-01-01

    We report the detection of radio emission from the unusually active L5e + T7 binary 2MASS J13153094-2649513AB made with the Australian Telescope Compact Array. Observations at 5.5 GHz reveal an unresolved source with a continuum flux of 370 ± 50 μJy, corresponding to a radio luminosity of L rad = νL ν = (9 ± 3)×1023 erg s-1 and log10 L rad/L bol = -5.44 ± 0.22. No detection is made at 9.0 GHz to a 5σ limit of 290 μJy, consistent with a power-law spectrum S νvpropν-α with α >~ 0.5. The emission is quiescent, with no evidence of variability or bursts over three hours of observation, and no measurable polarization (V/I < 34%). 2MASS J1315-2649AB is one of the most radio-luminous ultracool dwarfs detected in quiescent emission to date, comparable in strength to other cool sources detected in outburst. Its detection indicates no decline in radio flux through the mid-L dwarfs. It is unique among L dwarfs in having strong and persistent Hα and radio emission, indicating the coexistence of a cool, neutral photosphere (low electron density) and a highly active chromosphere (high electron density and active heating). These traits, coupled with the system's mature age and substellar secondary, make 2MASS J1315-2649AB an important test for proposed radio emission mechanisms in ultracool dwarfs.

  10. New shape models of asteroids reconstructed from sparse-in-time photometry

    NASA Astrophysics Data System (ADS)

    Durech, Josef; Hanus, Josef; Vanco, Radim; Oszkiewicz, Dagmara Anna

    2015-08-01

    Asteroid physical parameters - the shape, the sidereal rotation period, and the spin axis orientation - can be reconstructed from the disk-integrated photometry either dense (classical lightcurves) or sparse in time by the lightcurve inversion method. We will review our recent progress in asteroid shape reconstruction from sparse photometry. The problem of finding a unique solution of the inverse problem is time consuming because the sidereal rotation period has to be found by scanning a wide interval of possible periods. This can be efficiently solved by splitting the period parameter space into small parts that are sent to computers of volunteers and processed in parallel. We will show how this approach of distributed computing works with currently available sparse photometry processed in the framework of project Asteroids@home. In particular, we will show the results based on the Lowell Photometric Database. The method produce reliable asteroid models with very low rate of false solutions and the pipelines and codes can be directly used also to other sources of sparse photometry - Gaia data, for example. We will present the distribution of spin axis of hundreds of asteroids, discuss the dependence of the spin obliquity on the size of an asteroid,and show examples of spin-axis distribution in asteroid families that confirm the Yarkovsky/YORP evolution scenario.

  11. AN UPDATED CATALOG OF M33 CLUSTERS AND CANDIDATES: UBVRI PHOTOMETRY AND SOME STATISTICAL RESULTS

    SciTech Connect

    Ma Jun

    2012-08-15

    We present UBVRI photometry for 392 star clusters and candidates in the field of M33, which are selected from the most recent star cluster catalog. In this catalog, the authors listed star clusters' parameters such as cluster positions, magnitudes, colors in the UBVRIJHK{sub s} filters, and so on. However, a large fraction of objects in this catalog do not have previously published photometry. Photometry is performed using archival images from the Local Group Galaxies Survey, which covers 0.8 deg{sup 2} along the major axis of M33. Detailed comparisons show that, in general, our photometry is consistent with previous measurements. Positions (right ascension and declination) for some clusters are corrected here. Combined with previous literature, ours constitute a large sample of M33 star clusters. Based on this cluster sample, we present some statistical results: none of the youngest M33 clusters ({approx}10{sup 7} yr) have masses approaching 10{sup 5} M{sub Sun} ; roughly half the star clusters are consistent with the 10{sup 4}-10{sup 5} M{sub Sun} mass models; the continuous distribution of star clusters along the model line indicates that M33 star clusters have been formed continuously from the epoch of the first star cluster formation until recent times; and there are {approx}50 star clusters which are overlapped with the Galactic globular clusters on the color-color diagram, and these clusters are old globular cluster candidates in M33.

  12. Follow-up Photometry of the Galactic Nova ASASSN-16kt

    NASA Astrophysics Data System (ADS)

    Prieto, J. L.

    2016-09-01

    We obtained follow-up photometry of the Galactic Nova ASASSN-16kt (ATel #9538, #9539, #9550; CBET #4322) with a Celestron NexStar 4" telescope and a Canon EOS 300D camera observing from downtown Santiago (Chile), through variable clouds, on UT 2016 September 28.98 (JD = 2457660.47986).

  13. Determination of cyclamate by high-performance liquid chromatography with indirect photometry.

    PubMed

    Herrmann, A; Damawandi, E; Wagmann, M

    1983-12-01

    Most artificial sweeteners have been determined by high-performance liquid chromatography, but not cyclamate. We propose a simple method using standard equipment without any chemical reaction involving the cyclamate ion by applying the technique of indirect photometry. Saccharin, dulcin and aspartame may also be determined, if present.

  14. Photoelectric UBV photometry of variable stars observed during the years 1961-1999

    NASA Astrophysics Data System (ADS)

    Oja, T.

    2011-02-01

    Photoelectric UBV photometry of the variable stars V 636 Cas, alpha UMi, V 440 Per, zeta Gem, UU Cnc, TYC2-880-515-1, V 473 Lyr, chi Cyg, V 1794 Cyg, DT Cyg, V 1334 Cyg, V 532 Cyg, pi Aqr, and DY Peg is reported.

  15. VizieR Online Data Catalog: 1961-1999 UBV photometry of 14 variables (Oja, 2011)

    NASA Astrophysics Data System (ADS)

    Oja, T.

    2011-11-01

    Photoelectric UBV photometry of the variable stars V636 Cas, alpha UMi, V440 Per, zeta Gem, UU Cnc, TYC2-880-515-1, V473 Lyr, chi Cyg, V1794 Cyg, DT Cyg, V1334 Cyg, V532 Cyg, pi Aqr, and DY Peg is reported. (15 data files).

  16. THE CARNEGIE SUPERNOVA PROJECT: FIRST PHOTOMETRY DATA RELEASE OF LOW-REDSHIFT TYPE Ia SUPERNOVAE

    SciTech Connect

    Contreras, Carlos; Phillips, M. M.; Folatelli, Gaston; Stritzinger, Maximilian; Boldt, Luis; Gonzalez, Sergio; Krzeminski, Wojtek; Morrell, Nidia; Roth, Miguel; Salgado, Francisco; Hamuy, Mario; Maureira, MarIa Jose; Suntzeff, Nicholas B.; Persson, S. E.; Burns, Christopher R.; Freedman, W. L.; Madore, Barry F.; Murphy, David; Wyatt, Pamela

    2010-02-15

    The Carnegie Supernova Project (CSP) is a five-year survey being carried out at the Las Campanas Observatory to obtain high-quality light curves of {approx}100 low-redshift Type Ia supernovae (SNe Ia) in a well-defined photometric system. Here we present the first release of photometric data that contains the optical light curves of 35 SNe Ia, and near-infrared light curves for a subset of 25 events. The data comprise 5559 optical (ugriBV) and 1043 near-infrared (Y JHK{sub s} ) data points in the natural system of the Swope telescope. Twenty-eight SNe have pre-maximum data, and for 15 of these, the observations begin at least 5 days before B maximum. This is one of the most accurate data sets of low-redshift SNe Ia published to date. When completed, the CSP data set will constitute a fundamental reference for precise determinations of cosmological parameters, and serve as a rich resource for comparison with models of SNe Ia.

  17. Spitzer Photometry of WISE-Selected Brown Dwarf and Hyper-Lumninous Infrared Galaxy Candidates

    NASA Technical Reports Server (NTRS)

    Griffith, Roger L.; Kirkpatrick, J. Davy; Eisenhardt, Peter R. M.; Gelino, Christopher R.; Cushing, Michael C.; Benford, Dominic; Blain, Andrew; Bridge, Carrie R.; Cohen, Martin; Cutri, Roc M.; Donoso, Emilio; Jarrett, Thomas H.; Lonsdale, Carol; Mace, Gregory; Mainzer, A.; Marsh, Ken; Padgett, Deborah; Petty, Sara; Ressler, Michael E.; Skrutskie, Michael F.; Stanford, Spencer A.; Stern, Daniel; Tsai, Chao-Wei; Wright, Edward L.; Wu, Jingwen

    2012-01-01

    We present Spitzer 3.6 and 4.5 micrometer photometry and positions for a sample of 1510 brown dwarf candidates identified by the Wide-field Infrared Survey Explorer (WISE) all-sky survey. Of these, 166 have been spectroscopically classified as objects with spectral types M(1), L(7), T(146), and Y(12). Sixteen other objects are non-(sub)stellar in nature. The remainder are most likely distant L and T dwarfs lacking spectroscopic verification, other Y dwarf candidates still awaiting follow-up, and assorted other objects whose Spitzer photometry reveals them to be background sources. We present a catalog of Spitzer photometry for all astrophysical sources identified in these fields and use this catalog to identify seven fainter (4.5 m to approximately 17.0 mag) brown dwarf candidates, which are possibly wide-field companions to the original WISE sources. To test this hypothesis, we use a sample of 919 Spitzer observations around WISE-selected high-redshift hyper-luminous infrared galaxy candidates. For this control sample, we find another six brown dwarf candidates, suggesting that the seven companion candidates are not physically associated. In fact, only one of these seven Spitzer brown dwarf candidates has a photometric distance estimate consistent with being a companion to the WISE brown dwarf candidate. Other than this, there is no evidence for any widely separated (greater than 20 AU) ultra-cool binaries. As an adjunct to this paper, we make available a source catalog of 7.33 x 10(exp 5) objects detected in all of these Spitzer follow-up fields for use by the astronomical community. The complete catalog includes the Spitzer 3.6 and 4.5 m photometry, along with positionally matched B and R photometry from USNO-B; J, H, and Ks photometry from Two Micron All-Sky Survey; and W1, W2, W3, and W4 photometry from the WISE all-sky catalog.

  18. LIFTING THE DUSTY VEIL WITH NEAR- AND MID-INFRARED PHOTOMETRY. I. DESCRIPTION AND APPLICATIONS OF THE RAYLEIGH-JEANS COLOR EXCESS METHOD

    SciTech Connect

    Majewski, Steven R.; Zasowski, Gail; Nidever, David L. E-mail: gz2n@virginia.edu

    2011-09-20

    The Milky Way (MW) remains a primary laboratory for understanding the structure and evolution of spiral galaxies, but typically we are denied clear views of MW stellar populations at low Galactic latitudes because of extinction by interstellar dust. However, the combination of Two Micron All-Sky Survey (2MASS) near-infrared (NIR) and Spitzer-IRAC mid-infrared (MIR) photometry enables a powerful method for determining the line-of-sight reddening to any star: the sampled wavelengths lie in the Rayleigh-Jeans part of the spectral energy distribution of most stars, where, to first order, all stars have essentially the same intrinsic color. Thus, changes in stellar NIR-MIR colors due to interstellar reddening are readily apparent, and (under an assumed extinction law) the observed colors and magnitudes of stars can be easily and accurately restored to their intrinsic values, greatly increasing their usefulness for Galactic structure studies. In this paper, we explore this 'Rayleigh-Jeans Color Excess' (RJCE) method and demonstrate that use of even a simple variant of the RJCE method based on a single reference color, (H -[4.5{mu}]), can rather accurately remove dust effects from previously uninterpretable 2MASS color-magnitude diagrams of stars in fields along the heavily reddened Galactic midplane, with results far superior to those derived from application of other dereddening methods. We also show that 'total' Galactic midplane extinction looks rather different from that predicted using 100{mu} emission maps from the IRAS/ISSA and COBE/DIRBE instruments as presented by Schlegel et al. Instead, the Galactic midplane extinction strongly resembles the distribution of {sup 13}CO (J = 1{yields}0) emission. Future papers will focus on refining the RJCE method and applying the technique to understand better not only dust and its distribution but also the distribution of stars intermixed with the dust in the low-latitude Galaxy.

  19. The SDSS-2MASS-WISE 10-dimensional stellar colour locus

    NASA Astrophysics Data System (ADS)

    Davenport, James R. A.; Ivezić, Željko; Becker, Andrew C.; Ruan, John J.; Hunt-Walker, Nicholas M.; Covey, Kevin R.; Lewis, Alexia R.; AlSayyad, Yusra; Anderson, Lauren M.

    2014-06-01

    We present the fiducial main-sequence stellar locus traced by 10 photometric colours observed by Sloan Digital Sky Survey (SDSS), Two Micron All Sky Survey (2MASS), and Wide-field Infrared Survey Explorer (WISE). Median colours are determined using 1052 793 stars with r-band extinction less than 0.125. We use this locus to measure the dust extinction curve relative to the r band, which is consistent with previous measurements in the SDSS and 2MASS bands. The WISE band extinction coefficients are larger than predicted by standard extinction models. Using 13 lines of sight, we find variations in the extinction curve in H, Ks, and WISE bandpasses. Relative extinction decreases towards Galactic anticentre, in agreement with prior studies. Relative extinction increases with Galactic latitude, in contrast to previous observations. This indicates a universal mid-IR extinction law does not exist due to variations in dust grain size and chemistry with Galactocentric position. A preliminary search for outliers due to warm circumstellar dust is also presented, using stars with high signal-to-noise ratio in the W3 band. We find 199 such outliers, identified by excess emission in Ks - W3. Inspection of SDSS images for these outliers reveals a large number of contaminants due to nearby galaxies. Six sources appear to be genuine dust candidates, yielding a fraction of systems with infrared excess of 0.12 ± 0.05 per cent.

  20. Deriving star formation histories from photometry using energy balance spectral energy distribution modelling

    NASA Astrophysics Data System (ADS)

    Smith, Daniel J. B.; Hayward, Christopher C.

    2015-10-01

    Panchromatic spectral energy distribution fitting is a critical tool for determining the physical properties of distant galaxies, such as their stellar mass and star formation rate. One widely used method is the publicly available MAGPHYS code. We build on our previous analysis by presenting some modifications which enable MAGPHYS to automatically estimate galaxy star formation histories (SFHs), including uncertainties, based on ultraviolet to far-infrared photometry. We use state-of-the art synthetic photometry derived by performing three-dimensional dust radiative transfer on hydrodynamic simulations of isolated disc and merging galaxies to test how well the modified MAGPHYS is able to recover SFHs under idealized conditions, where the true SFH is known. We find that while the SFH of the model with the best fit to the synthetic photometry is a poor representation of the true SFH (showing large variations with the line of sight to the galaxy and spurious bursts of star formation), median-likelihood SFHs generated by marginalizing over the default MAGPHYS libraries produce robust estimates of the smoothly varying isolated disc simulation SFHs. This preference for the median-likelihood SFH is quantitatively underlined by our estimates of χ ^2_SFH (analogous to the χ2 goodness-of-fit estimator) and Δ M / M (the integrated absolute mass discrepancy between the model and true SFH) that strongly prefer the median-likelihood SFHs over those that best fit the UV-to-far-IR photometry. In contrast, we are unable to derive a good estimate of the SFH for the merger simulations (either best fit or median likelihood) despite being able to obtain a reasonable fit to the simulated photometry, likely because the analytic SFHs with bursts superposed in the standard MAGPHYS library are insufficiently general/realistic.

  1. INFORMATION ON THE MILKY WAY FROM THE 2MASS ALL SKY STAR COUNT: BIMODAL COLOR DISTRIBUTIONS

    SciTech Connect

    Chang, Chan-Kao; Lai, Shao-Yu; Peng, Ting-Hung; Ko, Chung-Ming E-mail: cmko@astro.ncu.edu.tw

    2012-11-10

    The J - K{sub s} color distributions (CDs) with a bin size of 0.05 mag has been carried out for the entire Milky Way using the Two Micron All Sky Survey Point Source Catalog (2MASS PSC). The CDs are bimodal, with a red peak at 0.8 < J - K{sub s} < 0.85 and a blue peak at 0.3 < J - K{sub s} < 0.4. The colors of the red peak are more or less the same for the whole sky, but those of the blue peak depend on Galactic latitude (J - K{sub s} {approx} 0.35 at low Galactic latitudes and 0.35 < J - K{sub s} < 0.4 for other sky areas). The blue peak dominates the bimodal CDs at low Galactic latitudes and becomes comparable with the red peak in other sky regions. In order to explain the bimodal distribution and the global trend shown by the all-sky 2MASS CDs, we assemble an empirical Hertzsprung-Russell (H-R) diagram, which is composed of observational-based near-infrared H-R diagrams and color-magnitude diagrams, and incorporate a Milky Way model. In the empirical H-R diagram, the main-sequence turn-off for stars in the thin disk is relatively bluer, (J - K{sub s} ){sub 0} = 0.31, compared with that of the thick disk which is (J - K{sub s} ){sub 0} = 0.39. The age of the thin/thick disk is roughly estimated to be around 4-5/8-9 Gyr according to the color-age relation of the main-sequence turn-off. In general, the 2MASS CDs can be treated as a tool to measure the age of the stellar population of the Milky Way in a statistical manner and to our knowledge it is the first attempt to do so.

  2. Supervoids in the WISE-2MASS catalogue imprinting cold spots in the cosmic microwave background

    NASA Astrophysics Data System (ADS)

    Finelli, F.; García-Bellido, J.; Kovács, A.; Paci, F.; Szapudi, I.

    2016-01-01

    The Cold Spot (CS) is a clear feature in the cosmic microwave background (CMB); it could be of primordial origin, or caused by a intervening structure along the line of sight. We identified a large projected underdensity in the recently constructed WISE-2MASS all-sky infrared galaxy catalogue aligned with the CS direction at (l, b) ≈ (209°, -57°). It has an angular size of tens of degrees, and shows a ˜20 per cent galaxy underdensity in the centre. Moreover, we find another large underdensity in the projected WISE-2MASS galaxy map at (l, b) ≈ (101°, 46°) (hereafter Draco supervoid), also aligned with a CMB decrement, although less significant than that of the CS direction. Motivated by these findings, we develop spherically symmetric Lemaitre-Tolman-Bondi (LTB) compensated void models to explain the observed CMB decrements with these two underdensities, or `supervoids'. Within our perturbative treatment of the LTB voids, we find that the integrated Sachs-Wolfe and Riess-Sciama effects due to the Draco supervoid can account for the CMB decrement observed in the same direction. On the contrary, the extremely deep CMB decrement in the CS direction is more difficult to explain by the presence of the CS supervoid only. Nevertheless, the probability of a random alignment between the CS and the corresponding supervoid is disfavoured, and thus its contribution as a secondary anisotropy cannot be neglected. We comment on how the approximations used in this paper, in particular the assumption of spherical symmetry, could change quantitatively our conclusions and might provide a better explanation for the CMB CS.

  3. A SEARCH FOR HIGH PROPER MOTION T DWARFS WITH Pan-STARRS1 + 2MASS + WISE

    SciTech Connect

    Liu, Michael C.; Deacon, Niall R.; Magnier, Eugene A.; Aller, Kimberly M.; Bowler, Brendan P.; Burgett, W. S.; Chambers, K. C.; Hodapp, K. W.; Kaiser, N.; Kudritzki, R.-P.; Morgan, J. S.; Tonry, J. L.; Wainscoat, R. J.; Dupuy, Trent J.; Redstone, Joshua; Goldman, Bertrand; Price, P. A.

    2011-10-20

    We have searched {approx}8200 deg{sup 2} for high proper motion ({approx}0.''5-2.''7 year{sup -1}) T dwarfs by combining first-epoch data from the Pan-STARRS1 (PS1) 3{pi} Survey, the Two Micron All Sky Survey (2MASS) All-Sky Point Source Catalog, and the WISE Preliminary Data Release. We identified two high proper motion objects with the very red (W1 - W2) colors characteristic of T dwarfs, one being the known T7.5 dwarf GJ 570D. Near-IR spectroscopy of the other object (PSO J043.5395+02.3995 {identical_to} WISEP J025409.45+022359.1) reveals a spectral type of T8, leading to a photometric distance of 7.2 {+-} 0.7 pc. The 2.''56 year{sup -1} proper motion of PSO J043.5+02 is the second highest among field T dwarfs, corresponding to a tangential velocity of 87 {+-} 8 km s{sup -1}. According to the Besancon galaxy model, this velocity indicates that its galactic membership is probably in the thin disk, with the thick disk an unlikely possibility. Such membership is in accord with the near-IR spectrum, which points to a surface gravity (age) and metallicity typical of the field population. We combine 2MASS, Sloan Digital Sky Survey, WISE, and PS1 astrometry to derive a preliminary parallax of 171 {+-} 45 mas (5.8{sup +2.0} {sub -1.2} pc), the first such measurement using PS1 data. The proximity and brightness of PSO J043.5+02 will facilitate future characterization of its atmosphere, variability, multiplicity, distance, and kinematics. The modest number of candidates from our search suggests that the immediate ({approx}10 pc) solar neighborhood does not contain a large reservoir of undiscovered T dwarfs earlier than about T8.

  4. Discovery of an X-Ray-emitting Contact Binary System 2MASS J11201034‑2201340

    NASA Astrophysics Data System (ADS)

    Hu, Chin-Ping; Yang, Ting-Chang; Chou, Yi; Liu, L.; Qian, S.-B.; Hui, C. Y.; Kong, Albert K. H.; Lin, L. C. C.; Tam, P. H. T.; Li, K. L.; Ngeow, Chow-Choong; Chen, W. P.; Ip, Wing-Huen

    2016-06-01

    We report the detection of orbital modulation, a model solution, and the X-ray properties of a newly discovered contact binary, Two Micron All Sky Survey (2MASS) J11201034‑2201340. We serendipitously found this X-ray point source outside the error ellipse when searching for possible X-ray counterparts of γ-ray millisecond pulsars among the unidentified objects detected by the Fermi Gamma-ray Space Telescope. The optical counterpart of the X-ray source (unrelated to the γ-ray source) was then identified using archival databases. The long-term Catalina Real-Time Transient Survey detected a precise signal with a period of P=0.28876208(56) days. A follow-up observation made by the Super Light Telescope of Lulin Observatory revealed the binary nature of the object. Utilizing archived photometric data of multi-band surveys, we construct the spectral energy distribution (SED), which is well fit by a K2V spectral template. The fitting result of the orbital profile using the Wilson–Devinney code suggests that 2MASS J11201034-2201340 is a short-period A-type contact binary and the more massive component has a cool spot. The X-ray emission was first noted in observations made by Swift, and then further confirmed and characterized by an XMM-Newton observation. The X-ray spectrum can be described by a power law or thermal Bremsstrahlung. Unfortunately, we could not observe significant X-ray orbital modulation. Finally, according to the SED, this system is estimated to be 690 pc from Earth with a calculated X-ray intensity of (0.7-1.5)× {10}30 erg s‑1, which is in the expected range of an X-ray emitting contact binary.

  5. Discovery of an X-Ray-emitting Contact Binary System 2MASS J11201034-2201340

    NASA Astrophysics Data System (ADS)

    Hu, Chin-Ping; Yang, Ting-Chang; Chou, Yi; Liu, L.; Qian, S.-B.; Hui, C. Y.; Kong, Albert K. H.; Lin, L. C. C.; Tam, P. H. T.; Li, K. L.; Ngeow, Chow-Choong; Chen, W. P.; Ip, Wing-Huen

    2016-06-01

    We report the detection of orbital modulation, a model solution, and the X-ray properties of a newly discovered contact binary, Two Micron All Sky Survey (2MASS) J11201034-2201340. We serendipitously found this X-ray point source outside the error ellipse when searching for possible X-ray counterparts of γ-ray millisecond pulsars among the unidentified objects detected by the Fermi Gamma-ray Space Telescope. The optical counterpart of the X-ray source (unrelated to the γ-ray source) was then identified using archival databases. The long-term Catalina Real-Time Transient Survey detected a precise signal with a period of P=0.28876208(56) days. A follow-up observation made by the Super Light Telescope of Lulin Observatory revealed the binary nature of the object. Utilizing archived photometric data of multi-band surveys, we construct the spectral energy distribution (SED), which is well fit by a K2V spectral template. The fitting result of the orbital profile using the Wilson-Devinney code suggests that 2MASS J11201034-2201340 is a short-period A-type contact binary and the more massive component has a cool spot. The X-ray emission was first noted in observations made by Swift, and then further confirmed and characterized by an XMM-Newton observation. The X-ray spectrum can be described by a power law or thermal Bremsstrahlung. Unfortunately, we could not observe significant X-ray orbital modulation. Finally, according to the SED, this system is estimated to be 690 pc from Earth with a calculated X-ray intensity of (0.7-1.5)× {10}30 erg s-1, which is in the expected range of an X-ray emitting contact binary.

  6. THE IMPACT OF CONTAMINATED RR LYRAE/GLOBULAR CLUSTER PHOTOMETRY ON THE DISTANCE SCALE

    SciTech Connect

    Majaess, D.; Turner, D.; Lane, D.; Gieren, W.

    2012-06-10

    RR Lyrae variables and the stellar constituents of globular clusters are employed to establish the cosmic distance scale and age of the universe. However, photometry for RR Lyrae variables in the globular clusters M3, M15, M54, M92, NGC 2419, and NGC 6441 exhibit a dependence on the clustercentric distance. For example, variables and stars positioned near the crowded high-surface brightness cores of the clusters may suffer from photometric contamination, which invariably affects a suite of inferred parameters (e.g., distance, color excess, absolute magnitude, etc.). The impetus for this study is to mitigate the propagation of systematic uncertainties by increasing awareness of the pernicious impact of contaminated and radial-dependent photometry.

  7. Combining Photometry from Kepler and TESS to Improve Short-period Exoplanet Characterization

    NASA Astrophysics Data System (ADS)

    Placek, Ben; Knuth, Kevin H.; Angerhausen, Daniel

    2016-07-01

    Planets emit thermal radiation and reflect incident light that they receive from their host stars. As a planet orbits its host star the photometric variations associated with these two effects produce very similar phase curves. If observed through only a single bandpass, this leads to a degeneracy between certain planetary parameters that hinder the precise characterization of such planets. However, observing the same planet through two different bandpasses gives much more information about the planet. Here we develop a Bayesian methodology for combining photometry from both Kepler and the Transiting Exoplanet Survey Satellite. In addition, we demonstrate via simulations that one can disentangle the reflected and thermally emitted light from the atmosphere of a hot-Jupiter as well as more precisely constrain both the geometric albedo and day-side temperature of the planet. This methodology can further be employed using various combinations of photometry from the James Webb Space Telescope, the Characterizing ExOplanet Satellite, or the PLATO mission.

  8. Combining Photometry from Kepler and TESS to Improve Short-Period Exoplanet Characterization

    NASA Technical Reports Server (NTRS)

    Placek, Ben; Knuth, Kevin H.; Angerhausen, Daniel

    2016-01-01

    Planets emit thermal radiation and reflect incident light that they receive from their host stars. As a planet orbits its host star the photometric variations associated with these two effects produce very similar phase curves. If observed through only a single bandpass, this leads to a degeneracy between certain planetary parameters that hinder the precise characterization of such planets. However, observing the same planet through two different bandpasses gives much more information about the planet. Here we develop a Bayesian methodology for combining photometry from both Kepler and the Transiting Exoplanet Survey Satellite. In addition, we demonstrate via simulations that one can disentangle the reflected and thermally emitted light from the atmosphere of a hot-Jupiter as well as more precisely constrain both the geometric albedo and day-side temperature of the planet. This methodology can further be employed using various combinations of photometry from the James Webb Space Telescope, the Characterizing ExOplanet Satellite, or the PLATO mission.

  9. Photometry-based estimation of the total number of stars in the Universe.

    PubMed

    Manojlović, Lazo M

    2015-07-20

    A novel photometry-based estimation of the total number of stars in the Universe is presented. The estimation method is based on the energy conservation law and actual measurements of the extragalactic background light levels. By assuming that every radiated photon is kept within the Universe volume, i.e., by approximating the Universe as an integrating cavity without losses, the total number of stars in the Universe of about 6×1022 has been obtained.

  10. BVRI CCD photometry of the metal-poor globular cluster M68 (NGC 4590)

    SciTech Connect

    Alcaino, G.; Liller, W.; Alvarado, F.; Wenderoth, E. )

    1990-06-01

    BVRI photometry of the low metallicity globular cluster M68 (NGC 4590) was obtained with a CCD camera and the 2.2-m ESO telescope. The resulting BV color-magnitude diagrams are compared with the observations of McClure et al. (1987). The observations are also compared with theoretical isochrones, yielding a cluster age of 13 Gyr with a likely external uncertainty of 2 or 3 Gyr. 25 refs.

  11. VizieR Online Data Catalog: VRIJHK photometry of 3C 279 (Sandrinelli+, 2016)

    NASA Astrophysics Data System (ADS)

    Sandrinelli, A.; Covino, S.; Dotti, M.; Treves, A.

    2016-07-01

    The starting point of the present investigation is the VRIJHK photometric observations obtained with the robotic Rapid Eye Mounting telescope (REM) at La Silla, which are described in detail in Sandrinelli et al. 2014 (cat. J/A+A/562/A79). We add to the data available in the above mentioned paper the REM photometry of 3C 279 (see Table2), which is unpublished thus far. (2 data files).

  12. VizieR Online Data Catalog: Segue 3 VI photometry (Ortolani+, 2013)

    NASA Astrophysics Data System (ADS)

    Ortolani, S.; Bica, E.; Barbuy, B.

    2015-01-01

    Johnson-Cousins V and I images were obtained at the Telescopio Nazionale Galileo (TNG), equipped with the spectrograph/focal reducer DOLORES, with a 2000x2000-pixels of 8.5x8.5-arcmin2 CCD giving 0.25arcsec/pix, during the night of 2011 June 26-27. Additional B, V and I photometry was obtained, with the same equipment, in the night of 2012 June 17-18. (2 data files).

  13. Documentation for the machine-readable version of the thirteen color photometry of 1380 bright stars

    NASA Technical Reports Server (NTRS)

    Warren, W. H., Jr.; Roman, N. G.

    1981-01-01

    The magnetic tape version of the catalogue of thirteen-color photometry of 1380 bright stars, containing data on the 13 color medium narrow band photometric system is described. Observations of essentially all stars brighter than fifth visual magnitude north of delta = -20 deg and brighter than fourth visual magnitude south of delta = -20 deg are included. It is intended to enable users to read and process the tape without the common difficulties and uncertainties.

  14. Multi-band Differential Photometry of the Eclipsing Variable Star NSVS 5750160

    NASA Astrophysics Data System (ADS)

    Berrington, R. C.; Tuhey, E. M.

    2014-12-01

    We present new multi-band differential aperture photometry of the eclipsing variable star NSVS 5750160. The light curves are analyzed with the Wilson-Devinney model to determine best-fit stellar models. Our models show that NSVS 5750160 is consistent with a W-type W Ursae Majoris eclipsing variable star, and require the presence of a spot to fit the observed O’Connell effect. Two different spot models are presented but neither model is conclusive.

  15. Multicolor surface photometry of powerful radio galaxies. I - Observations and data reduction

    NASA Technical Reports Server (NTRS)

    Smith, Eric P.; Heckman, T. M.

    1989-01-01

    The first of a series of papers which explore the optical morphology, photometric properties, and colors of powerful radio galaxies is presented. This paper reports the observations and data reduction process. The surface photometry techniques used in the analysis are described and the calibration of the results is given. The resulting images reveal that a significant fraction of powerful radio galaxies are morphologically distorted and that many of these galaxies have unusual colors. Results for individual objects are discussed.

  16. ASPIN: Research project on near-Earth asteroid photometry in frame of the ISON optical network

    NASA Astrophysics Data System (ADS)

    Molotov, Igor; Inasaridze, Raguli; Elenin, Leonid; Krugly, Yurij; Rumyantsev, Vasilij; Namkhai, Tungalag; Schmalz, Sergei; Tsogt-Ochir, Shijirbayar

    International Scientific Optical Network (ISON) represents one of largest systems specializing in observation of space objects. The main goal of project is observations of space debris. As an additional task the regular photometry of near-Earth asteroids (NEAs) is carried out using the network’s telescopes with apertures from 0.4 m up to 2.6 m (ASPIN project - Asteroid Search and Photometry Initiative). The photometry is aimed at getting lightcurves of asteroids for solving different tasks concerning with physical properties of these celestial bodies. The lightcurves have been obtained with a typical photometric accuracy of 0.01-0.03 mag. The main purpose of the observations is to study characteristics of asteroids such as rotation period, size and shape of the body, surface composition and other. It is expected to detect an influence of the YORP effect. Special attention is paid to the detection of binary asteroids. During 2013 the photometric observations have been carried out at 12 observatories during more than 250 nights which have been allowed to obtain the data on 40 NEAs as well as 15 main-belt asteroids. In result the rotation periods have been determined for 8 NEAs in the first time and refined for 10 NEAs. Two binary systems were discovered. Lightcurves of 11 main-belt asteroids with diameters less than 10 km (binary systems or members of small clusters) were obtained. Several of the observed asteroids were radar targets - between them the NEA (367943) Duende (or 2012 DA14), which was approached to the Earth in day of falling the Chelyabinsk meteor on February 23, 2013. The obtained results will be presented and perspectives of NEA photometry with ISON telescopes will be discussed.

  17. VizieR Online Data Catalog: Near-IR photometry in VVV CL08 (Ramirez Alegria+, 2014)

    NASA Astrophysics Data System (ADS)

    Ramirez Alegria, S.; Borissova, J.; Chene, A. N.; O'Leary, E.; Amigo, P.; Minniti, D.; Saito, R. K.; Geisler, D.; Kurtev, R.; Hempel, M.; Gromadzki, M.; Clarke, J. R. A.; Negueruela, I.; Marco, A.; Fierro, C.; Bonatto, C.; Catelan, M.

    2014-03-01

    Near infrared (J, H and Ks) photometry for the cluster most probable members. We use the VVV-SkZ pipeline (Mauro et al. 2013RMxAA..49..189M), to measure the photometry over the VVV stacked images. We determine the most probable members using the decontamination algorithm from Bonatto & Bica (2010A&A...516A..81B), as described by Borissova et al. (2011, Cat. J/A+A/532/A131). (1 data file).

  18. New 1982-1990 photometry of Lambda Andromedae and its 11-year cycle

    NASA Technical Reports Server (NTRS)

    Hall, Douglas S.; Henry, Gregory W.; Boehme, Dietmar; Brooks, Peter A.; Chang, Sandy; Dolzan, Ales; Fortier, George L.; Fried, Robert E.; Genet, Russell M.; Grim, Bruce S.

    1991-01-01

    The paper presents photoelectric photometry of Lambda And never before published, obtained between February 1982 and December 1990 at 29 different observatories. Then it is combined with all other photometry available (previously published, contained in the I.A.U. Commission 27 Archives, and obtained with the Vanderbilt 16-inch automatic telescope but not yet published), to yield a 14.8-year data base. Analysis reveals a long-term cycle in mean brightness, with a full range of 0.15 m and a period of 11.4 +/- 0.4 years. Because most of the new photometry was concentrated in the 1983-1984 observing season, this one well-defined light curve is analyzed with a two-spot model. Spot A keeps a 0.04 m amplitude throughout four rotation cycles whereas the amplitude of spot B diminishes from 0.09 m down almost to 0.03 m. The spot rotation periods were 55.9 d +/- 0.6 d and 52.8 d +/- 1.0 d, respectively.

  19. Detecting Bias in a Self-Organizing Map of Galaxy Photometry Data

    NASA Astrophysics Data System (ADS)

    Claytor, Zachary R.

    2016-01-01

    High redshift (very distant) galaxy surveys record broad-band photometry for billions of galaxies in order to measure distances in a faster, more cost-effective way than spectroscopy. Knowing these distances (more specifically, the redshifts) helps cosmologists learn more about the early universe and how it evolved, but calibrating the redshifts from photometry requires a color-selection technique. One such technique is the Self-Organizing Map (SOM), a machine-learning algorithm that projects high-dimensional photometry data onto a visual, two-dimensional map. High-redshift galaxies can be identified efficiently in such a mapping. However, there is a chance that high-redshift galaxies are lost to low-redshift regions and vice versa due to photometric error; this effect was analyzed. A Monte Carlo simulation was run on objects selected from along the boundary between high- and low-redshift regions. Roughly 18% of selected objects scattered from high- to low-redshift, and about 16% scattered the other way. Further research will design a better metric of the scattering percentages based on the number density of galaxies in the map, and future work should use these analysis techniques on other high-redshift data.

  20. VizieR Online Data Catalog: Westerlund 2 UBVIc photometry (Hur+, 2015)

    NASA Astrophysics Data System (ADS)

    Hur, H.; Park, B.-G.; Sung, H.; Bessell, M. S.; Lim, B.; Chun, M.-Y.; Sohn, S. T.

    2015-06-01

    Deep UBVIC observations were obtained on 2009 March 28 and 2 the 8kx8k Mosaic II CCD camera (0.268arcsec/pix) of the 4m Blanco telescope at Cerro Tololo Inter-American Observatory (CTIO). We used the SDSS u filter for U-band photometry and the Harris BVI filter set for BVIC photometry. The exposure times were 7 and 150s in I, 10 and 300s in V, 20 and 300s in B, and 100 and 1200 s in u. The average seeing was ~0.9-arcsec. For the photometry of bright stars and for the standardization of U-B, we performed additional observations with the Y4KCam CCD camera and UBVIC filter set of the 1m telescope at CTIO on 2011 March 5. The exposure times were 5 and 180s in I, 5 and 180s in V, 10 and 300s in B, and 30 and 600s in U. (2 data files).

  1. Spectroscopy and Strömgren Photometry in the Young Open Cluster NGC 2169

    NASA Astrophysics Data System (ADS)

    Yost, C. C.; Gray, R. O.; Murdick, L.; Robinson, P.

    2000-12-01

    NGC 2169 is a young (1.5 x 107 yr) open cluster in Orion with no associated nebulosity. As part of our program of searching for peculiar stars in open clusters, we have obtained classification--resolution (1.8Å/2 pixels) spectra for 23 stars, low--resolution (20Å/2 pixels) spectra for an additional 9 stars, and Strömgren uvby photometry for 40 stars in the field of NGC 2169 down to V ~ 15.5. The observations were made on the 0.8 meter telescope of Appalachian State University's Dark Sky Observatory. NGC 2169 appears to have very few members later than spectral type A3. However, the Strömgren photometry yields 5 new candidate members of NGC 2169, plus a population of possible but not probable pre--main--sequence stars. The spectroscopy shows that most stars in NGC 2169 are normal, except for two helium--weak B--type stars, and a mild Silicon Bp star. More spectroscopy and photometry is planned in the field. This project has been partially funded by a small AAS Grant, plus an Undergraduate Research Scholarship from the Graduate School of Appalachian State University to C.C. Yost. We would also like to acknowledge a grant from the Fund for Astrophysical Research.

  2. A SEARCH FOR THE TRANSIT OF HD 168443b: IMPROVED ORBITAL PARAMETERS AND PHOTOMETRY

    SciTech Connect

    Pilyavsky, Genady; Mahadevan, Suvrath; Wright, Jason T.; Wang, Xuesong X.; Kane, Stephen R.; Ciardi, David R.; Dragomir, Diana; Von Braun, Kaspar; Howard, Andrew W.; De Pree, Chris; Marlowe, Hannah; Fischer, Debra; Henry, Gregory W.; Jensen, Eric L. N.; Laughlin, Gregory

    2011-12-20

    The discovery of transiting planets around bright stars holds the potential to greatly enhance our understanding of planetary atmospheres. In this work we present the search for transits of HD 168443b, a massive planet orbiting the bright star HD 168443 (V = 6.92) with a period of 58.11 days. The high eccentricity of the planetary orbit (e = 0.53) significantly enhances the a priori transit probability beyond that expected for a circular orbit, making HD 168443 a candidate for our ongoing Transit Ephemeris Refinement and Monitoring Survey. Using additional radial velocities from Keck High Resolution Echelle Spectrometer, we refined the orbital parameters of this multi-planet system and derived a new transit ephemeris for HD 168443b. The reduced uncertainties in the transit window make a photometric transit search practicable. Photometric observations acquired during predicted transit windows were obtained on three nights. Cerro Tololo Inter-American Observatory 1.0 m photometry acquired on 2010 September 7 had the required precision to detect a transit but fell just outside of our final transit window. Nightly photometry from the T8 0.8 m automated photometric telescope at Fairborn Observatory, acquired over a span of 109 nights, demonstrates that HD 168443 is constant on a timescale of weeks. Higher-cadence photometry on 2011 April 28 and June 25 shows no evidence of a transit. We are able to rule out a non-grazing transit of HD 168443b.

  3. 2MASS J22560844+5954299: the newly discovered cataclysmic star with the deepest eclipse

    NASA Astrophysics Data System (ADS)

    Kjurkchieva, D.; Khruzina, T.; Dimitrov, D.; Groebel, R.; Ibryamov, S.; Nikolov, G.

    2015-12-01

    Context. The SW Sex stars are assumed to represent a distinguished stage in cataclysmic variable (CV) evolution, making it especially important to study them. Aims: We discovered a new cataclysmic star and carried out prolonged and precise photometric observations, as well as medium-resolution spectral observations. Modelling these data allowed us to determine the physical parameters and to establish its peculiarities. Methods: To obtain a light curve solution we used model whose emission sources are a white dwarf surrounded by an accretion disk with a hot spot, a gaseous stream near the disk's lateral side, and a secondary star filling its Roche lobe. The obtained physical parameters are compared with those of other SW Sex-subtype stars. Results: The newly discovered cataclysmic variable 2MASS J22560844+5954299 shows the deepest eclipse amongst the known nova-like stars. It was reproduced by totally covering a very luminous accretion disk by a red secondary component. The temperature distribution of the disk is flatter than that of steady-state disk. The target is unusual with the combination of a low mass ratio q ~ 1.0 (considerably below the limit q = 1.2 of stable mass transfer of CVs) and an M-star secondary. The intensity of the observed three emission lines, Hα, He 5875, and He 6678, sharply increases around phase 0.0, accompanied by a Doppler jump to the shorter wavelength. The absence of eclipses of the emission lines and their single-peaked profiles means that they originate mainly in a vertically extended hot-spot halo. The emission Hα line reveals S-wave wavelength shifts with semi-amplitude of around 210 km s-1 and phase lag of 0.03. Conclusions: The non-steady-state emission of the luminous accretion disk of 2MASS J22560844+5954299 was attributed to the low viscosity of the disk matter caused by its unusually high temperature. The star shows all spectral properties of an SW Sex variable apart from the 0.5 central absorption. Based on data collected

  4. Discovery of a Very Young Field L Dwarf, 2MASS J01415823-4633574

    NASA Astrophysics Data System (ADS)

    Kirkpatrick, J. Davy; Barman, Travis S.; Burgasser, Adam J.; McGovern, Mark R.; McLean, Ian S.; Tinney, Christopher G.; Lowrance, Patrick J.

    2006-03-01

    While following up L dwarf candidates selected photometrically from the Two Micron All Sky Survey, we uncovered an unusual object designated 2MASS J01415823-4633574. Its optical spectrum exhibits very strong bands of vanadium oxide but abnormally weak absorptions by titanium oxide, potassium, and sodium. Morphologically, such spectroscopic characteristics fall intermediate between old field early-L dwarfs [log(g)~5] and very late M giants [log(g)~0], leading us to favor low gravity as the explanation for the unique spectral signatures of this L dwarf. Such a low gravity can be explained only if this L dwarf is much lower in mass than a typical old field L dwarf of similar temperature and is still contracting to its final radius. These conditions imply a very young age. Further evidence of youth is found in the near-infrared spectrum, including a triangular-shaped H-band continuum, reminiscent of young brown dwarf candidates discovered in the Orion Nebula Cluster. Using the above information along with comparisons to brown dwarf atmospheric and interior models, our current best estimate is that this L dwarf has an age of 1-50 Myr and a mass of 6-25MJ. Although the lack of a lithium detection (pseudo-equivalent width <1 Å) might appear to contradict other evidence of youth, we suggest that lithium becomes weaker at lower gravity like all other alkali lines and thus needs to be carefully considered before being used as a diagnostic of age or mass for objects in this regime. The location of 2MASS 0141-4633 on the sky coupled with a distance estimate of ~35 pc and the above age estimate suggests that this object may be a brown dwarf member of either the 30 Myr old Tucana/Horologium association or the ~12 Myr old β Pic moving group. Distance as determined through trigonometric parallax (underway) and a measure of the total space motion are needed to test this hypothesis. Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as

  5. Long Period Variables in the LMC: Results from MACHO and 2Mass

    SciTech Connect

    Fraser, O J; Cook, K H; Keller, S C; Hawley, S L

    2004-07-19

    We use the eight year light curve database from the MACHO (MAssive Compact Halo Objects) project together with infrared colors and magnitudes from 2MASS (the Two Micron All Sky Survey) to identify a sample of 22,000 long period variables in the Large Magellanic Cloud (referred to hereafter as LMC LPVs). A period luminosity diagram of these stars reveals six well defined sequences, in substantial agreement with previous analyses of samples from OGLE (Optical Gravitational Lensing Experiment). In our analysis we identify analogues to galactic LPVs in the LMC LPV sample. We find that carbon dominated AGB stars populate only two of the sequences, one of which includes the Mira variables. The high luminosity end of the same two sequences are also the location of the only stars with J K{sub s} > 2, indicating that they are enshrouded in dust. The unknown mechanism that produces the variability of the last sequence--those stars with long secondary periods--produces different morphology in the period luminosity diagram than what is seen in the first four sequences, which are thought to be caused by pulsation. In particular, the last sequence extends to lower luminosity RGB stars and the luminosity function does not peak among the AGB stars. We point out several features which will constrain new models of the period luminosity sequences.

  6. Using the 2-MASS photometric redshift survey to optimize LIGO follow-up observations

    NASA Astrophysics Data System (ADS)

    Antolini, Elisa; Heyl, Jeremy S.

    2016-10-01

    The initial discovery of Laser Interferometer Gravitational-Wave Observatory (LIGO) on 2015 September 14 was the inspiral merger and ring-down of the black hole binary at a distance of about 500 Mpc or a redshift of about 0.1. The search for electromagnetic counterparts for the inspiral of binary black holes is impeded by coarse initial source localizations and a lack of a compelling model for the counterpart; therefore, rapid electromagnetic follow-up is required to understand the astrophysical context of these sources. Because astrophysical sources of gravitational radiation are likely to reside in galaxies, it would make sense to search first in regions where the LIGO-Virgo probability is large and where the density of galaxies is large as well. Under the assumption that the probability of a gravitational-wave event from a given region of space is proportional to the density of galaxies within the probed volume, one can calculate an improved localization of the position of the source simply by multiplying the LIGO-Virgo skymap by the density of galaxies in the range of redshifts. We propose using the 2-MASS photometric redshift galaxy catalogue for this purpose and demonstrate that using it can dramatically reduce the search region for electromagnetic counterparts.

  7. A Recalibration of Optical Photometry: Tycho-2, Strömgren, and Johnson Systems

    NASA Astrophysics Data System (ADS)

    Maíz Apellániz, J.

    2006-02-01

    I use high-quality Hubble Space Telescope (HST) spectrophotometry to analyze the calibration of three popular optical photometry systems: Tycho-2 BT and VT, Strömgren uvby, and Johnson UBV. For Tycho-2, I revisit the analysis of an earlier paper to include the new recalibration of grating/aperture corrections, vignetting, and charge transfer inefficiency effects produced by the Space Telescope Imaging Spectrograph group and to consider the consequences of both random and systematic uncertainties. The new results reaffirm the good quality of both the Tycho-2 photometry and the HST spectrophotometry but yield a slightly different value for ZPBT-VT of 0.033+/-0.001 (random) +/-0.005 (systematic) mag. For the Strömgren v, b, and y filters I find that the published sensitivity curves are consistent with the available photometry and spectrophotometry, and I derive new values for the associated ZPb-y and ZPm1. The same conclusion is drawn for the Johnson B and V filters and the associated ZPB-V. The situation is different for the Strömgren u and the Johnson U filters. There I find that the published sensitivity curves yield results that are inconsistent with the available photometry and spectrophotometry, likely caused by an incorrect treatment of atmospheric effects on the short-wavelength end. I reanalyze the data to produce new average sensitivity curves for those two filters and new values for ZPc1 and ZPU-B. The new computation of synthetic U-B and B-V colors uses a single B sensitivity curve, which eliminates the previous unphysical existence of different definitions for each color. Finally, I find that if one uses values from the literature for which uncertainties are not given, reasonable estimates for these are 1%-2% for Strömgren b-y, m1, and c1 and 2%-3% for Johnson B-V and U-B. The use of the results in this paper should lead to a significant reduction of systematic errors when comparing synthetic photometry models with real colors and indices.

  8. New Neighbors from 2MASS: Activity and Kinematics at the Bottom of the Main Sequence

    NASA Astrophysics Data System (ADS)

    Gizis, John E.; Monet, David G.; Reid, I. Neill; Kirkpatrick, J. Davy; Liebert, James; Williams, Rik J.

    2000-08-01

    We have combined 2MASS and POSS II data in a search for nearby ultracool (later than M6.5) dwarfs with Ks<12. Spectroscopic follow-up observations identify 53 M7-M9.5 dwarfs and seven L dwarfs. The observed space density is 0.0045+/-0.0008 M8-M9.5 dwarfs per cubic parsec, without accounting for biases, consistent with a mass function that is smooth across the stellar/substellar limit. We show the observed frequency of Hα emission peaks at ~100% for M7 dwarfs and then decreases for cooler dwarfs. In absolute terms, however, as measured by the ratio of Hα to bolometric luminosity, none of the ultracool M dwarfs can be considered very active compared to earlier M dwarfs, and we show that the decrease that begins at spectral type M6 continues to the latest L dwarfs. We find that flaring is common among the coolest M dwarfs and estimate the frequency of flares at 7% or higher. We show that the kinematics of relatively active (EW>6 Å) ultracool M dwarfs are consistent with an ordinary old disk stellar population, while the kinematics of inactive ultracool M dwarfs are more typical of a 0.5 Gyr old population. The early L dwarfs in the sample have kinematics consistent with old ages, suggesting that the hydrogen-burning limit is near spectral types L2-L4. We use the available data on M and L dwarfs to show that chromospheric activity drops with decreasing mass and temperature and that at a given (M8 or later) spectral type, the younger field (brown) dwarfs are less active than many of the older, more massive field stellar dwarfs. Thus, contrary to the well-known stellar age-activity relationship, low activity in field ultracool dwarfs can be an indication of comparative youth and substellar mass.

  9. Variable stars in the VVV globular clusters. I. 2MASS-GC 02 and Terzan 10

    SciTech Connect

    Alonso-García, Javier; Dékány, István; Catelan, Márcio; Ramos, Rodrigo Contreras; Gran, Felipe; Leyton, Paul; Minniti, Dante; Amigo, Pía E-mail: idekany@astro.puc.cl E-mail: rcontrer@astro.puc.cl E-mail: pia.amigo@uv.cl E-mail: dante@astrofisica.cl

    2015-03-01

    The VISTA Variables in the Vía Láctea (VVV) ESO Public Survey is opening a new window to study inner Galactic globular clusters (GCs) using their variable stars. These GCs have been neglected in the past due to the difficulties caused by the presence of elevated extinction and high field stellar densities in their lines of sight. However, the discovery and study of any present variables in these clusters, especially RR Lyrae stars, can help to greatly improve the accuracy of their physical parameters. It can also help to shed some light on the questions raised by the intriguing Oosterhoff dichotomy in the Galactic GC system. In a series of papers we plan to explore variable stars in the GCs falling inside the field of the VVV survey. In this first paper, we search for and study the variables present in two highly reddened, moderately metal-poor, faint, inner Galactic GCs: 2MASS-GC 02 and Terzan 10. We report the discovery of sizable populations of RR Lyrae stars in both GCs. We use near-infrared period–luminosity relations to determine the color excess of each RR Lyrae star, from which we obtain both accurate distances to the GCs and the ratios of the selective-to-total extinction in their directions. We find the extinction toward both clusters to be elevated, non-standard, and highly differential. We also find both clusters to be closer to the Galactic center than previously thought, with Terzan 10 being on the far side of the Galactic bulge. Finally, we discuss their Oosterhoff properties, and conclude that both clusters stand out from the dichotomy followed by most Galactic GCs.

  10. VizieR Online Data Catalog: Young and embedded clusters in Cygnus-X (Maia+, 2016)

    NASA Astrophysics Data System (ADS)

    Maia, F. F. S.; Moraux, E.; Joncour, I.

    2016-02-01

    CFHT/WIRCam was used to acquire deep (960s, 1200s, 480s) JHK exposures of five fields covering ~1 degree squared in the Cygnus-X complex, in six nights between 04/09/2012 and 29/10/2012. The frames were detrended and coadded into a master mosaic where PSF photometry was carried out using SExtractor and PSFex software using a 2-sigma detection threshold. The resulting catalog was calibrated against the 2MASS catalog, but no transformation was done to our data. Instead, bright sources (brighter than the saturation magnitude) were recovered from 2MASS and calibrated to the WIRCam instrumental system to complement our catalog. The final table contains about 310000 stars spanning 12 magnitudes and reaching K=18.5 at 95% completeness. The fundamental parameters of 10 young stellar systems in the region were derived through this final catalogue. (2 data files).

  11. Direct measurement and calibration of the Kepler CCD Pixel Response Function for improved photometry and astrometry

    NASA Astrophysics Data System (ADS)

    Ninkov, Zoran

    Stellar images taken with telescopes and detectors in space are usually undersampled, and to correct for this, an accurate pixel response function is required. The standard approach for HST and KEPLER has been to measure the telescope PSF combined ("convolved") with the actual pixel response function, super-sampled by taking into account dithered or offset observed images of many stars (Lauer [1999]). This combined response function has been called the "PRF" (Bryson et al. [2011]). However, using such results has not allowed astrometry from KEPLER to reach its full potential (Monet et al. [2010], [2014]). Given the precision of KEPLER photometry, it should be feasible to use a pre-determined detector pixel response function (PRF) and an optical point spread function (PSF) as separable quantities to more accurately correct photometry and astrometry for undersampling. Wavelength (i.e. stellar color) and instrumental temperature should be affecting each of these differently. Discussion of the PRF in the "KEPLER Instrument Handbook" is limited to an ad-hoc extension of earlier measurements on a quite different CCD. It is known that the KEPLER PSF typically has a sharp spike in the middle, and the main bulk of the PSF is still small enough to be undersampled, so that any substructure in the pixel may interact significantly with the optical PSF. Both the PSF and PRF are probably asymmetric. We propose to measure the PRF for an example of the CCD sensors used on KEPLER at sufficient sampling resolution to allow significant improvement of KEPLER photometry and astrometry, in particular allowing PSF fitting techniques to be used on the data archive.

  12. Correlation between anterior chamber characteristics and laser flare photometry immediately after femtosecond laser treatment before phacoemulsification.

    PubMed

    Pahlitzsch, M; Torun, N; Pahlitzsch, M L; Klamann, M K J; Gonnermann, J; Bertelmann, E; Pahlitzsch, T

    2016-08-01

    PurposeTo assess the anterior chamber (AC) characteristics and its correlation to laser flare photometry immediately after femtosecond laser-assisted capsulotomy and photodisruption.Patients and methodsThe study included 97 cataract eyes (n=97, mean age 68.6 years) undergoing femtosecond laser-assisted cataract surgery (FLACS). Three cohorts were analysed relating to the flare photometry directly post femtosecond laser treatment (flare <100 n=28, 69.6±7 years; flare 100-249 n=47, 67.7±8 years; flare >249 photon counts per ms cohort n=22, 68.5±10 years). Flare photometry (KOWA FM-700), corneal topography (Oculus Pentacam, Germany: AC depth, volume, angle, pachymetry), axial length, pupil diameter, and endothelial cells were assessed before FLACS, immediately after femtosecond laser treatment and 1 day postoperative (LenSx Alcon, USA). Statistical data were analysed by SPSS v19.0, Inc.ResultsThe AC depth, AC volume, AC angle, central and thinnest corneal thickness showed a significant difference between flare <100 vs flare 100-249 10 min post femtosecond laser procedure (P=0.002, P=0.023, P=0.007, P=0.003, P=0.011, respectively). The AC depth, AC volume, and AC angle were significantly larger (P=0.001, P=0.007, P=0.003, respectively) in the flare <100 vs flare >249 cohort 10 min post femtosecond laser treatment.ConclusionsA flat AC, low AC volume, and a narrow AC angle were parameters associated with higher intraocular inflammation. These criteria could be used for patient selection in FLACS to reduce postoperative intraocular inflammation.

  13. Diagnostic potential of endotoxin scattering photometry for sepsis and septic shock.

    PubMed

    Shimizu, Tomoharu; Obata, Toru; Sonoda, Hiromichi; Akabori, Hiroya; Miyake, Tohru; Yamamoto, Hiroshi; Tabata, Takahisa; Eguchi, Yutaka; Tani, Tohru

    2013-12-01

    Endotoxin scattering photometry (ESP) is a novel Limulus amebocyte lysate (LAL) assay that uses a laser light-scattering particle-counting method. In the present study, we compared ESP, standard turbidimetric LAL assay, and procalcitonin assay for the evaluation of sepsis after emergency gastrointestinal surgery. A total of 174 samples were collected from 40 adult patients undergoing emergency gastrointestinal surgery and 10 patients with colorectal cancer undergoing elective surgery as nonseptic controls. Plasma endotoxin levels were measured with ESP and turbidimetric LAL assay, and plasma procalcitonin levels were assessed with a standard procalcitonin assay. Plasma endotoxin and procalcitonin levels increased corresponding to the degree of sepsis. Endotoxin scattering photometry significantly discriminated between patients with or without septic shock: sensitivity, 81.1%; specificity, 76.6%; positive predictive value, 48.4%; negative predictive value, 93.8%; and accuracy, 77.6%. The area under the receiver operating characteristic curve for septic shock with the ESP assay (endotoxin cutoff value, 23.8 pg/mL) was 0.8532 ± 0.0301 (95% confidence interval, 0.7841-0.9030; P < 0.0001). The predictive power of ESP was superior to that of turbidimetric assay (difference, 0.1965 ± 0.0588; 95% confidence interval, 0.0812-0.3117; P = 0.0008). There was no significant difference in predictive power between ESP and procalcitonin assay. Endotoxin scattering photometry also discriminated between patients with and without sepsis. Area under the receiver operating characteristic curve analysis showed that ESP had the best predictive power for diagnosing sepsis. In conclusion, compared with turbidimetric LAL assay, ESP more sensitively detected plasma endotoxin and significantly discriminated between sepsis and septic shock in patients undergoing gastrointestinal emergency surgery.

  14. Using Herschel Far-Infrared Photometry to Constrain Star Formation Rates in CLASH Cluster Galaxies

    NASA Astrophysics Data System (ADS)

    Larson, Rebecca L.; Postman, Marc; Fogarty, Kevin

    2016-01-01

    The Cluster Lensing And Supernova survey with Hubble (CLASH) program obtained broadband images of 25 massive galaxy clusters in 16 passbands from the UV to the near-IR. The data was taken with the Wide-field Camera 3 (WFC3), and the Advanced Camera for Surveys (ACS) on the Hubble Space Telescope (HST). These 25 clusters have also been observed in the mid-IR by Spitzer IRAC, the far-IR by the Herschel Space Observatory PACS and SPIRE, and in the x-ray by the Chandra and XMM observatories. We focused on the two brightest cluster galaxies (BCGs) in the survey (MACS1931.8-2653 and RXJ1532.9+3021) that have reddening-corrected UV-derived star formation rates (SFRs) > 100 M⊙ yr-1 as measured by Fogarty et al (2015). The inclusion of Herschel data provides unique constraints on dust content and independent estimates of the star formation rates in these interesting galaxies. We performed photometry on the five Herschel bands (100-500μm), and removed any contamination from other cluster members. We fit a UV-FIR SED to each galaxy to measure the bolometric dust luminosity (Lbol), which we use to derive the FIR obscured SFR. We calculate the sum of the measured UV unobscured SFR from the HST photometry and the FIR obscured SFR from the Herschel photometry to get a total SFR for these two BCGs. We compared this to the reddening-corrected SFRs and found they were in agreement within error. This confirms that the Kennicutt and Calzetti methods for calculating star formation rates are both applicable for these highly star-forming massive cluster galaxies.

  15. The AAVSO Photoelectric Photometry Program in its Scientific and Socio-Historic Context

    NASA Astrophysics Data System (ADS)

    Percy, John R.

    2011-05-01

    Photoelectric photometry began in the 1900s through the work of Guthnick, Stebbins, and others who constructed and used photometers based on the recently-discovered photoelectric effect. The mid 20th century saw a confluence of several areas of amateur interest: astronomy, telescope making, radio and electronics, and general interest in space. This is the time when AAVSO photoelectric photometry (PEP) began, with observers using mostly hand-built photometers on hand-built telescopes. The 1980s brought a revolution: affordable off-the-shelf solid-state photometers, and infrastructure such as the International Amateur-Professional Photoelectric Photometry (IAPPP) conferences, books, and journal. The AAVSO developed a formal PEP program in the early 1980s. Its emphasis was on long-term monitoring of pulsating red giants. It was competing, not always successfully, with programs such as active sun-like binaries (RS CVn stars) which offered "instant gratification" in the form of publicity and quick publications. Nevertheless, the AAVSO PEP program has, through careful organization, motivation, and feedback to observers, produced extensive scientific results. In this presentation, I shall describe, as examples, my own work, its scientific significance, its educational benefit to dozens of my students, and its satisfaction to the observers. To some extent, the AAVSO PEP program has been superceded by its CCD program, but there is still a useful place for ongoing PEP observations of thousands of variable stars. Reference: http://www.aavso.org/sites/default/files/newsletter/PEP/lastpepnl.pdf Acknowledgements: I thank NSERC Canada for research support, my students, and AAVSO staff and observers, especially Howard Landis.

  16. MOST photometry and modeling of the rapidly oscillating (roAp) star γ Equulei

    NASA Astrophysics Data System (ADS)

    Gruberbauer, M.; Saio, H.; Huber, D.; Kallinger, T.; Weiss, W. W.; Guenther, D. B.; Kuschnig, R.; Matthews, J. M.; Moffat, A. F. J.; Rucinski, S.; Sasselov, D.; Walker, G. A. H.

    2008-03-01

    Aims:Despite photometry and spectroscopy of its oscillations obtained over the past 25 years, the pulsation frequency spectrum of the rapidly oscillating Ap (roAp) star γ Equ has remained poorly understood. Better time-series photometry, combined with recent advances to incorporate interior magnetic field geometry into pulsational models, enable us to perform improved asteroseismology of this roAp star. Methods: We obtained 19 days of continuous high-precision photometry of γ Equ with the Most (Microvariability & Oscillations of STars) satellite. The data were reduced with two different reduction techniques and significant frequencies were identified. Those frequencies were fitted by interpolating a grid of pulsation models that include dipole magnetic fields of various polar strengths. Results: We identify 7 frequencies in γ Equ that we associate with 5 high-overtone p-modes and 1st and 2nd harmonics of the dominant p-mode. One of the modes and both harmonics are new discoveries for this star. Our best model solution (1.8 M⊙, log T_eff ~3.882; polar field strength ~8.1 kG) leads to unique mode identifications for these frequencies (ℓ = 0, 1, 2 and 4). This is the first purely asteroseismic fit to a grid of magnetic models. We measure amplitude and phase modulation of the primary frequency due to beating with a closely spaced frequency that had never been resolved. This casts doubts on theories that such modulation - unrelated to the rotation of the star - is due to a stochastic excitation mechanism. Based on data from the Most satellite, a Canadian Space Agency mission, jointly operated by Dynacon Inc., the University of Toronto Institute of Aerospace Studies and the University of British Columbia with the assistance of the University of Vienna.

  17. Quasar probabilities and redshifts from WISE mid-IR through GALEX UV photometry

    NASA Astrophysics Data System (ADS)

    DiPompeo, M. A.; Bovy, J.; Myers, A. D.; Lang, D.

    2015-09-01

    Extreme deconvolution (XD) of broad-band photometric data can both separate stars from quasars and generate probability density functions for quasar redshifts, while incorporating flux uncertainties and missing data. Mid-infrared photometric colours are now widely used to identify hot dust intrinsic to quasars, and the release of all-sky WISE data has led to a dramatic increase in the number of IR-selected quasars. Using forced photometry on public WISE data at the locations of Sloan Digital Sky Survey (SDSS) point sources, we incorporate this all-sky data into the training of the XDQSOz models originally developed to select quasars from optical photometry. The combination of WISE and SDSS information is far more powerful than SDSS alone, particularly at z > 2. The use of SDSS+WISE photometry is comparable to the use of SDSS+ultraviolet+near-IR data. We release a new public catalogue of 5537 436 (total; 3874 639 weighted by probability) potential quasars with probability PQSO > 0.2. The catalogue includes redshift probabilities for all objects. We also release an updated version of the publicly available set of codes to calculate quasar and redshift probabilities for various combinations of data. Finally, we demonstrate that this method of selecting quasars using WISE data is both more complete and efficient than simple WISE colour-cuts, especially at high redshift. Our fits verify that above z ˜ 3 WISE colours become bluer than the standard cuts applied to select quasars. Currently, the analysis is limited to quasars with optical counterparts, and thus cannot be used to find highly obscured quasars that WISE colour-cuts identify in significant numbers.

  18. The Void Galaxy Survey: photometry, structure and identity of void galaxies

    NASA Astrophysics Data System (ADS)

    Beygu, B.; Peletier, R. F.; van der Hulst, J. M.; Jarrett, T. H.; Kreckel, K.; van de Weygaert, R.; van Gorkom, J. H.; Aragon-Calvo, M. A.

    2016-09-01

    We analyze photometry from deep B-band images of 59 void galaxies in the Void Galaxy Survey (VGS), together with their near-infrared 3.6μm and 4.5μm Spitzer photometry. The VGS galaxies constitute a sample of void galaxies that were selected by a geometric-topological procedure from the SDSS DR7 data release, and which populate the deep interior of voids. Our void galaxies span a range of absolute B-magnitude from {M_B=-15.5} to {M_B=-20}, while at the 3.6μm band their magnitudes range from {M_{3.6}=-18} to {M_{3.6}=-24}. Their B-[3.6] colour and structural parameters indicate these are star forming galaxies. A good reflection of the old stellar population, the near-infrared band photometry also provide a robust estimate of the stellar mass, which for the VGS galaxies we confirm to be smaller than 3 × 1010 M⊙. In terms of the structural parameters and morphology, our findings align with other studies in that our VGS galaxy sample consists mostly of small late-type galaxies. Most of them are similar to Sd-Sm galaxies, although a few are irregularly shaped galaxies. The sample even includes two early-type galaxies, one of which is an AGN. Their Sérsic indices are nearly all smaller than n = 2 in both bands and they also have small half-light radii. In all, we conclude that the principal impact of the void environment on the galaxies populating them mostly concerns their low stellar mass and small size.

  19. Bayesian High-redshift Quasar Classification from Optical and Mid-IR Photometry

    NASA Astrophysics Data System (ADS)

    Richards, Gordon T.; Myers, Adam D.; Peters, Christina M.; Krawczyk, Coleman M.; Chase, Greg; Ross, Nicholas P.; Fan, Xiaohui; Jiang, Linhua; Lacy, Mark; McGreer, Ian D.; Trump, Jonathan R.; Riegel, Ryan N.

    2015-08-01

    We identify 885,503 type 1 quasar candidates to i≲ 22 using the combination of optical and mid-IR photometry. Optical photometry is taken from the Sloan Digital Sky Survey-III: Baryon Oscillation Spectroscopic Survey (SDSS-III/BOSS), while mid-IR photometry comes from a combination of data from the Wide-field Infrared Survey Explorer (WISE) “AllWISE” data release and several large-area Spitzer Space Telescope fields. Selection is based on a Bayesian kernel density algorithm with a training sample of 157,701 spectroscopically confirmed type 1 quasars with both optical and mid-IR data. Of the quasar candidates, 733,713 lack spectroscopic confirmation (and 305,623 are objects that we have not previously classified as photometric quasar candidates). These candidates include 7874 objects targeted as high-probability potential quasars with 3.5\\lt z\\lt 5 (of which 6779 are new photometric candidates). Our algorithm is more complete to z\\gt 3.5 than the traditional mid-IR selection “wedges” and to 2.2\\lt z\\lt 3.5 quasars than the SDSS-III/BOSS project. Number counts and luminosity function analysis suggest that the resulting catalog is relatively complete to known quasars and is identifying new high-z quasars at z\\gt 3. This catalog paves the way for luminosity-dependent clustering investigations of large numbers of faint, high-redshift quasars and for further machine-learning quasar selection using Spitzer and WISE data combined with other large-area optical imaging surveys.

  20. VizieR Online Data Catalog: Infrared photometry of Galactic and MC PN (Phillips+, 2009)

    NASA Astrophysics Data System (ADS)

    Phillips, J. P.; Ramos-Larios, G.

    2015-07-01

    We have acquired photometry and mapping of a wide range of Galactic disc, Galactic bulge, and LMC PNe using data deriving from the second Galactic Legacy Infrared Mid-plane Survey Extraordinaire (GLIMPSE II) (Benjamin et al., 2003PASP..115..953B, Cat. II/293), and the program Surveying the Agents of a Galaxy.s Evolution (SAGE; Meixner et al., 2006AJ....132.2268M, Cat. J/AJ/132/2268). Both of these surveys were undertaken using the Spitzer Space Telescope (SST; Werner et al., 2004ApJS..154....1W). (3 data files).

  1. Target selection of classical pulsating variables for space-based photometry

    NASA Astrophysics Data System (ADS)

    Plachy, E.; Molnar, L.; Szabo, R.; Kolenberg, K.; Banyai, E.

    2016-05-01

    In a few years the Kepler and TESS missions will provide ultra- precise photometry for thousands of RR Lyrae and hundreds of Cepheid stars. In the extended Kepler mission all targets are proposed in the Guest Observer (GO) Program, while the TESS space telescope will work with full frame images and a ~15-16th mag brightness limit with the possibility of short cadence measurements for a limited number of pre-selected objects. This paper highlights some details of the enormous and important work of the target selection process made by the members of Working Group 7 (WG#7) of the Kepler and TESS Asteroseismic Science Consortium.

  2. Statistical error analysis in CCD time-resolved photometry with applications to variable stars and quasars

    NASA Technical Reports Server (NTRS)

    Howell, Steve B.; Warnock, Archibald, III; Mitchell, Kenneth J.

    1988-01-01

    Differential photometric time series obtained from CCD frames are tested for intrinsic variability using a newly developed analysis of variance technique. In general, the objects used for differential photometry will not all be of equal magnitude, so the techniques derived here explicitly correct for differences in the measured variances due to photon statistics. Other random-noise terms are also considered. The technique tests for the presence of intrinsic variability without regard to its random or periodic nature. It is then applied to observations of the variable stars ZZ Ceti and US 943 and the active extragalactic objects OQ 530, US 211, US 844, LB 9743, and OJ 287.

  3. Wavelet analysis of fast photometry on Cygnus X-1 with the AstraLux camera

    SciTech Connect

    Luque-Escamilla, P. L.; Marti, J.; Combi, Jorge A.; Arjonilla, Alvaro Munoz; Sanchez-Sutil, J. R.

    2008-10-08

    We present sub-second fast photometry for the high mass X-ray binary Cygnus X-1. We try to observe variability due to instabilities in the accretion process at optical wavelengths. The observations were carried out using the high speed AstraLux camera at the Calar Alto 2.2 m telescope, Spain, in November 2006 and August 2007. We report that the Cygnus X-1 system light curve sampled every 30 milli-second did not display strong enough evidence of any periodic component related to the source.

  4. Ultraviolet photometry of Nova Cygni 1992 obtained with the high speed photometer

    NASA Technical Reports Server (NTRS)

    Taylor, M.; Bless, R. C.; Oegelman, H.; Elliot, J. L.; Gallagher, J. S.; Nelson, M. J.; Percival, J. W.; Robinson, E. L.; Van Citters, G. W.

    1994-01-01

    In this Letter we present the first high-speed ultraviolet photometry of an active, classical nova, Nova Cygni 1992. The 45 minute observation shows significant evidence for power at frequencies that correspond to periods of about 565 and 900 s. Each of these periods has an amplitude of about 3 mmag. Since this data set is short, we cannot establish the nature of the detected variability and so, we discuss possible physical mechanisms ranging from short-lived phenomena to stable periodic modulations that could result in the observed variations.

  5. Ultraviolet photometry from the Orbiting Astronomical Observatory. XXI - Absolute energy distribution of stars in the ultraviolet

    NASA Technical Reports Server (NTRS)

    Bless, R. C.; Code, A. D.; Fairchild, E. T.

    1976-01-01

    The absolute energy distribution in the ultraviolet is given for the stars alpha Vir, eta UMa, and alpha Leo. The calibration is based on absolute heterochromatic photometry between 2920 and 1370 A carried out with an Aerobee sounding rocket. The fundamental radiation standard is the synchrotron radiation from 240-MeV electrons in a certain synchrotron storage ring. On the basis of the sounding-rocket calibration, the preliminary OAO-2 spectrometer calibration has been revised; the fluxes for the three program stars are tabulated in energy per second per square centimeter per unit wavelength interval.

  6. Determination of water pollution by the oil products through UV photometry.

    PubMed

    Winkler, Igor; Agapova, Nataliya

    2010-09-01

    Results of UV photometry of water/gasoline systems are reported. It was found that this system can be characterized with an analytical light absorption peak with maximum at 260 nm. A calibrating diagram for optical density vs. gasoline content has been built for this peak and concentration limits of the gasoline compounds' solubility in water were found. The peak pattern and its position indicate that 1,3,5-trimethylbenzene and/or its closest homologs can be those gasoline compounds, which reveal themselves through the UV light absorption peak.

  7. The Secret Lives of Cepheids: Searching for Evolutionary Changes Using Photoelectric Photometry

    NASA Astrophysics Data System (ADS)

    Toce, Michael; Guinan, Edward F.; Engle, Scott G.; Wasatonic, Richard P.

    2016-01-01

    Classical Cepheids are pulsating, yellow supergiants and one of the most important classes of variable stars. They have a direct linear relationship between their period and luminosity and thus serve as crucial "standard candles" for determining the cosmic distance scale and measuring the Hubble Constant. Also, Cepheids play a fundamental role in the calibration of Type Ia supernovae, indicating that the expansion of the Universe is accelerating, and also infer the existence of dark energy. Studies of changes in their pulsation periods and amplitudes reveal evolutionary changes too subtle to detect directly, and understanding these various characteristics of Cepheids is critical to their use as high-precision standard candles. To this end, the Villanova Secret Lives of Cepheids (SLiC) program was created as a comprehensive study of Cepheid behavior, evolution, pulsations, atmospheres, heating dynamics, shocks and winds. As part of the SLiC program, ground-based photometry is being carried out of small sample of bright Cepheids. The observations are being made using the 14-inch reflector telescope at Villanova Campus Observatory. Mounted on the telescope is a SBIG photoelectric photometer equipped with standard Johnson UBVRI filters. Photometry is being carried out of the following stars along with their spectral type, period, and visual mag: X Cyg (F7Ib, ~16.39d, 6.47mag), DT Cyg (F7.5Ib, ~2.5d, 5.82mag), S Sge (G5Ibv, ~8.38d, 5.36mag), FF Aql (F6Ib, ~4.47d, 5.38mag), Eta Aql (F6Iab, ~7.18d,3.80mag), and Delta Cep (F5Iab, ~5.37d, 3.75mag). The primary scientific objectives are to obtain light curves to investigate possible evolutionary changes from small variations in luminosity, light amplitude and pulsation period. Special emphasis was placed on the classical Cepheid X Cyg due to recent changes in pulsation period, shown by Szabados via a phase jump in X Cyg's O-C (observed - calculated). X Cyg holds priority in our observations as we attempt to affirm or deny

  8. Ultraviolet photometry from the Orbiting Astronomical Observatory. XI - The 1971 eclipse of 32 Cygni

    NASA Technical Reports Server (NTRS)

    Doherty, L. R.; Mcnall, J. F.; Holm, A. V.

    1974-01-01

    We observed the 1971 eclipse of 32 Cyg at regular intervals from November 1 to 15 with the wide-band filter photometers aboard OAO-2. Data have been reduced for seven filter bands with effective wavelengths between 4250 and 1430 A. Both the constancy of the light near mid-eclipse for the shorter wavelengths, and the derived energy distribution of the B component over all of these wavelengths indicate that the eclipse was total. The spectral types determined from the photometry of the two components are B5 and K4 Ib, after correction for interstellar reddening of 0.10 mag in B-V.

  9. NEW g'r'i'z' PHOTOMETRY OF THE NGC 5128 GLOBULAR CLUSTER SYSTEM

    SciTech Connect

    Sinnott, Brendan; Hou, Annie; Harris, William E.; Anderson, Rachel; Woodley, Kristin A. E-mail: houa2@physics.mcmaster.c E-mail: randers@stsci.ed

    2010-12-15

    We present new photometry for 323 of the globular clusters in NGC 5128 (Centaurus A), measured for the first time in the g'r'i'z' filter system. The color indices are calibrated directly to standard stars in the g'r'i'z' system and are used to establish the fiducial mean colors for the blue and red (low and high metallicity) globular cluster sequences. We also use spectroscopically measured abundances to establish the conversion between the most metallicity-sensitive colors ((g' - r'){sub 0}, (g' - i'){sub 0}) and metallicity, [Fe/H].

  10. PSF homogenization for multi-band photometry from space on extended objects

    NASA Astrophysics Data System (ADS)

    Boucaud, A.; Dole, H.; Abergel, A.; Ayasso, H.; Orieux, F.

    2016-09-01

    We present a fast and robust tool to create PSF matching kernels for multi-band photometric studies. Such kernels are useful for convolving images down to the same PSF prior to computing flux measurements like aperture photometry or spectral fitting. Unlike similar existing methods, we use a Wiener filter to take into account the real shape of the effective PSF, usually very complex for space telescopes. We apply this scheme to Euclid simulated PSF images to demonstrate the efficiency of the algorithm. This tool is publicly available http://www.github.io/aboucaud/pypher.

  11. H-alpha Confirmation, Astrometry and Photometry of Two Novae in M31

    NASA Astrophysics Data System (ADS)

    Hornoch, K.; Vaduvescu, O.; Gonzalez, A.

    2013-06-01

    We obtained five 120-s narrow-band H-alpha and three 90-s R-band CCD frames of the central region of M31 on 2013 June 27.189 and 27.193 UT, respectively, with the 2.5-m Isaac Newton Telescope + WFC at La Palma under ~2.0" seeing. The single frames were co-added and the co-added images were used for photometry and astrometry of the two recently discovered and spectroscopically unconfirmed M31 nova candidates, namely the PNV J00424894+4115163 (ATel #5133) and PNV J00425987+4120379 (ATel #5157).

  12. High-fidelity photometry and astrometry of high-contrast imaged companions using LOCI processing.

    NASA Astrophysics Data System (ADS)

    Maire, Jérôme; Gagné, Jonathan; Lafrenière, David; Graham, James R.; Doyon, René

    2014-01-01

    abstract-type="normal"> Résumé Direct imaging and spectroscopy of exoplanets is a key element for understanding planet formation and migration. Such direct detections and characterizations remains technologically challenging, since a very high contrast ratio and small angular separation are involved, and futhermore speckle noise limits the high-contrast imaging performance. We further discuss a speckle subtraction and suppression technique that fully takes advantage of spectral and time-domain information on quasi-static speckles to measure the highest-fidelity photometry as well as accurate astrometry of detected companions.

  13. VizieR Online Data Catalog: Photometry of globulars in early galaxies (Chies-Santos+, 2011)

    NASA Astrophysics Data System (ADS)

    Chies-Santos, A. L.; Larsen, S. S.; Wehner, E. M.; Kuntschner, H.; Strader, J.; Brodie, J. P.

    2010-10-01

    We acquired deep K-band images of 14 bright nearby early-type galaxies. The images were obtained with the LIRIS near-infrared spectrograph and imager at the William Herschel Telescope (WHT) and combined with optical ACS g and z images from the Hubble Space Telescope public archive. Table 4 contains ACS and LIRIS photometry and sizes for the GC systems of NGC3377, NGC4278, NGC4365, NGC4374, NGC4382, NGC4406, NGC4473, NGC4486, NGC4526, NGC4552, NGC4570, NGC4621, NGC4649, NGC4660. (1 data file).

  14. Optical Photometry of the flaring gamma-ray blazar AO 0235+164

    NASA Astrophysics Data System (ADS)

    Pursimo, Tapio; Losada, Illa R.; Messa, Matteo; Gafton, Emanuel; Ojha, Roopesh

    2016-03-01

    We report optical photometry of the blazar AO 0235+164 obtained with the 2.56m Nordic Optical Telescope in La Palma to look for any enhanced optical activity associated with a recent flare in the daily averaged gamma-ray flux seen in the public lightcurve of the Fermi/LAT instrument: http://fermi.gsfc.nasa.gov/FTP/glast/data/lat/catalogs/asp/current/lightcurves/0235+164_86400.png Fermi/LAT first reported a detection of gamma-ray activity from this source in Sep, 2008 (ATel#1744) and a short timescale flare in Oct 14, 2008 (ATel#1784).

  15. Another neon nova - Early infrared photometry and spectroscopy of Nova Cygni 1992

    NASA Technical Reports Server (NTRS)

    Hayward, T. L.; Gehrz, R. D.; Miles, J. W.; Houck, J. R.

    1992-01-01

    Infrared photometry and spectrophotometry of Nova Cygni 1992 taken within 54 days of its eruption show a strong 12.8-micron Ne II forbidden emission line as well as hydrogen recombination lines. Spectra with lambda/Delta lambda of about 2000 resolve the Ne II forbidden and 12.37-micron Hu-alpha lines with about 2200 km/s (FWHM). The Ne II forbidden line shows multiple velocity components. The amount of forbidden Ne II required to produce the observed emission feature exceeds the solar abundance of neon by at least a factor of 4.

  16. EMCCD SPECKLE INTERFEROMETRY WITH THE 6 m TELESCOPE: ASTROMETRIC MEASUREMENTS, DIFFERENTIAL PHOTOMETRY, AND ORBITS

    SciTech Connect

    Docobo, Jose A.; Tamazian, Vakhtang S.; Melikian, Norair D. E-mail: vakhtang.tamazian@usc.e E-mail: nmelikia@bao.sci.a

    2010-10-15

    Results of the EMCCD-based speckle interferometric observations and differential photometry for 46 visual binaries obtained in 2007 June and July with the 6 m telescope of the Special Astrophysical Observatory (Russia) are presented. First preliminary orbits for COU 401, COU 1281, and COU 1037 as well as improved orbits for CHR 137, COU 100, COU 1136, COU 798, CHR 51, CHR 55, COU 315, COU 206, and ADS 13961, along with their dynamical mass estimates, are reported. On the basis of dynamical parallax information, first distance estimates for COU 100, COU 1136, COU 798, COU 206, and COU 1037 are calculated.

  17. VizieR Online Data Catalog: UBV photometry of HD 143418 (Bozic+, 2007)

    NASA Astrophysics Data System (ADS)

    Bozic, H.; Wolf, M.; Harmanec, P.; Prsa, A.; Percy, J. R.; Ruzdjak, D.; Sudar, D.; Slechta, M.; Ak, H.; Eenens, P.

    2006-11-01

    After a serendipitious discovery that HD 143418 is a light variable, we analyzed numerous UBV observations and Hipparcos Hp magnitudes transformed to Johnson V to find out whether the object is a very unusual spectroscopic binary. Initial reductions of new photometry were carried out with the HEC22 program, while the new spectra were reduced in the IRAF and SPEFO programs. Orbital elements were derived with the FOTEL program, the KOREL disentangling was applied, and period searches were carried out using phase dispersion minimalization technique and the program PERIOD04. Final modeling of radial-velocity and light variations was carried out in PHOEBE. (1 data file).

  18. 15 years of comet photometry: A comparative analysis of 80 comets

    NASA Technical Reports Server (NTRS)

    Osip, David J.; Schleicher, David G.; Millis, Robert L.; Hearn, M. F. A.; Birch, P. V.

    1992-01-01

    In 1976 we began a program of narrowband photometry of comets that has encompassed well over 400 nights of observations. To date, the program has provided detailed information on 80 comets, 11 of which have been observed on multiple apparitions. In this paper we present the observed range of compositions (molecular production rate ratios) and dustiness (gas production compared with AF-rho) for a well sampled group of comets. Based on these results we present preliminary analysis of taxonomic groupings as well as the abundance ratios we associate with a 'typical' comet.

  19. Photoelectric photometry of diffuse gaseous nebulae in the H-alpha line

    NASA Astrophysics Data System (ADS)

    Vidal, J.-L.

    1980-04-01

    Results are given of the H-alpha photometry of diffuse gaseous nebulae observed with a nebula photometer attached to the 60-cm reflector of the Pic du Midi Observatory. Isophote maps are given for the following objects: the Orion nebula, the Rosette nebula, IC 410, IC 434 and NGC 2024, and M 8 (NGC 6523); several scans are presented for NGC 6514, NGC 7000, and Barnard's Loop. In cases where the spherical model approximation may be performed, the variation of electron density with radius was determined; for the Rosette nebula a steeper decrease toward the center than previously established was found.

  20. Outer planet Grand Tour missions photometry/polarimetry experiment critical components study

    NASA Technical Reports Server (NTRS)

    Pellicori, S. F.; Russell, E. E.; Watts, L. A.

    1972-01-01

    Work performed during this effort was limited to two primary areas of technical concern: optical design optimization, and sensor selection. An optical system concept was established, and various system components were evaluated through experimental test sequences. Photodetectors were investigated for the applicability in meeting OPGT requirements as constrained by the photometry/polarimetry team directives. The most promising (gallium arsenide PMT) was further experimentally tested to ascertain its behavior with respect to anticipated environmental conditions. Results of testing and summary of the preceding tradeoff study effort are presented.

  1. Physical parameters of NGC6705 (M11) open cluster using Strömgren photometry

    NASA Astrophysics Data System (ADS)

    Casamiquela, L.; Balaguer-Núñez, L.; Jordi, C.; Masana, E.

    2015-05-01

    NGC 6705 (M11) is a middle-age well-studied open cluster. Its location in an area where the interstellar extinction is relatively low, its exceptional stellar density and richness, and the presence of both early type and evolved stars makes this cluster an interesting target for many scientific issues. Although NGC 6705 has been widely studied, Strömgren photometry was missing. The observations by our team have yielded uvbyH photometry for 51293 stars in an area of 34'×34' and with V_{lim}˜21. Observed stars with complete photometry (9308) are classified into photometric regions and their physical parameters are determined using standard relations among color indices for each of the photometric regions of the HR diagram. That allows us to provide an astrophysical characterization of the cluster: E(b-y)=0.31±0.05 (E(B-V)=0.42); V_{0}-M_{V}=11.9±0.7 (d˜2000pc); [Fe/H]=-0.2±0.4 (Z=0.009). In addition, we discuss the accuracy of the physical parameters through comparison with those recently determined by Beaver et al. (2013) with Strömgren photometry. We find mean systematic differences of Δ V=-0.015±0.038, Δ (b-y)=-0.017±0.046, Δ m_{1}=-0.014±0.092, Δ c_{1}=+0.014±0.131, and Δ β=-0.036±0.042. These are caused by different selection of reference stars for the instrumental-to-standard transformation. We also compare our results with those from the spectroscopic Gaia-ESO Survey (GES) to assess the quality of the photometric determinations. This work can be useful to give input astrophysical parameters to the spectral analyses being made by GES. We find out clear different trends for the stars bluer and redder than (b-y)=0.4 (T_{eff}˜8000 K), due to the different instrumental setups used for the GIRAFFE observations (HR3 and HR15N). We find that mean differences in effective temperatures and gravities for both works are compatible within the errors. However, mean difference in metallicity for stars with (b-y)>0.4 is discrepant by -0.65 dex.

  2. Far ultraviolet wide field imaging and photometry - Spartan-202 Mark II Far Ultraviolet Camera

    NASA Technical Reports Server (NTRS)

    Carruthers, George R.; Heckathorn, Harry M.; Opal, Chet B.; Witt, Adolf N.; Henize, Karl G.

    1988-01-01

    The U.S. Naval Research Laboratory' Mark II Far Ultraviolet Camera, which is expected to be a primary scientific instrument aboard the Spartan-202 Space Shuttle mission, is described. This camera is intended to obtain FUV wide-field imagery of stars and extended celestial objects, including diffuse nebulae and nearby galaxies. The observations will support the HST by providing FUV photometry of calibration objects. The Mark II camera is an electrographic Schmidt camera with an aperture of 15 cm, a focal length of 30.5 cm, and sensitivity in the 1230-1600 A wavelength range.

  3. DWARF IRREGULAR GALAXY LEO A: SUPRIME-CAM WIDE-FIELD STELLAR PHOTOMETRY

    SciTech Connect

    Stonkutė, Rima; Narbutis, Donatas; Vansevičius, Vladas; Arimoto, Nobuo; Hasegawa, Takashi; Tamura, Naoyuki

    2014-10-01

    We have surveyed a complete extent of Leo A—an apparently isolated gas-rich low-mass dwarf irregular galaxy in the Local Group. The B, V, and I passband CCD images (typical seeing ∼0.''8) were obtained with the Subaru Telescope equipped with the Suprime-Cam mosaic camera. The wide-field (20' × 24') photometry catalog of 38,856 objects (V ∼ 16-26 mag) is presented. This survey is also intended to serve as ''a finding chart'' for future imaging and spectroscopic observation programs of Leo A.

  4. Association of Lp-PLA2 Mass and Aysmptomatic Intracranial and Extracranial Arterial Stenosis in Hypertension Patients

    PubMed Central

    Wang, Yan; Zhang, Jin; Qian, Yuesheng; Tang, Xiaofeng; Ling, Huawei; Chen, Kemin; Gao, Pingjin; Zhu, Dingliang

    2015-01-01

    Background and Purpose Intracranial arterial stenosis (ICAS) is a common cause of ischemic stroke in Asians, whereas whites tend to have more extracranial lesions. Lipoprotein-associated phospholipase A2 (Lp-PLA2) has been associated with ischemic stroke by a large amount of work. However, there are few studies focusing on the relationship of Lp-PLA2 and asymptomatic ICAS or extracranial arterial stenosis (ECAS). Wehereby sought to explore the relationship of Lp-PLA2 and ICAS, ECAS and concurrent stenosis in stroke-free hypertensive patients in Chinese population. Methods All the subjects were evaluated for the presence and severity of ICAS and ECAS through computerized tomographic angiography (CTA) covered the whole brain down to the level of aortic arch. Lp-PLA2 mass was measured by enzyme linked immunoassay. The association of Lp-PLA2 and vascular stenosis was analyzed through multivariate logistic regression. Results Among 414 participants, 163 (39.4%) had no ICAS or ECAS, 63 (15.2%) had ECAS only, 111 (26.8%) had ICAS only and 77 (18.6%) had concurrent extraintracranial stenosis. Lp-PLA2 mass was significantly associated with isolated ICAS (OR: 2.3; 95% CI: 1.14-4.64), and concurrent stenosis (OR: 3.93; 95% CI: 1.62-9.51), but was not related to isolated ECAS (OR: 1.54; 95% CI: 0.68-3.48). Lp-PLA2 mass was also associated with moderate to severe ICAS no matter how was the ECAS. Moreover, patients with higher Lp-PLA2 mass showed more sever ICAS and had more intracranial arterial lesions. Conclusion This study revealed the association of Lp-PLA2 mass with ICAS in stroke-free hypertensive patients in Chinese population. The further long-term cohort study was warranted to elucidate the concrete effect of Lp-PLA2 on the asymptomatic ICAS. PMID:26098634

  5. WISE TF: A MID-INFRARED, 3.4 {mu}m EXTENSION OF THE TULLY-FISHER RELATION USING WISE PHOTOMETRY

    SciTech Connect

    Lagattuta, David J.; Mould, Jeremy R.; Staveley-Smith, Lister; Hong Tao; Springob, Christopher M.; Masters, Karen L.; Koribalski, Baerbel S.; Jones, D. Heath

    2013-07-10

    We present a mid-infrared Tully-Fisher (TF) relation using photometry from the 3.4 {mu}m W1 band of the Wide-field Infrared Survey Explorer (WISE) satellite. The WISE TF relation is formed from 568 galaxies taken from the all-sky 2MASS Tully-Fisher (2MTF) galaxy catalog, spanning a range of environments including field, group, and cluster galaxies. This constitutes the largest mid-infrared TF relation constructed to date. After applying a number of corrections to galaxy magnitudes and line widths, we measure a master TF relation given by M{sub corr} = -22.24 - 10.05[log (W{sub corr}) - 2.5], with an average dispersion of {sigma}{sub WISE} = 0.686 mag. There is some tension between WISE TF and a preliminary 3.6 {mu}m relation, which has a shallower slope and almost no intrinsic dispersion. However, our results agree well with a more recent relation constructed from a large sample of cluster galaxies. We additionally compare WISE TF to the near-infrared 2MTF template relations, finding a good agreement between the TF parameters and total dispersions of WISE TF and the 2MTF K-band template. This fact, coupled with typical galaxy colors of (K - W1) {approx} 0, suggests that these two bands are tracing similar stellar populations, including the older, centrally-located stars in the galactic bulge which can (for galaxies with a prominent bulge) dominate the light profile.

  6. Simple Photometry

    ERIC Educational Resources Information Center

    Mills, Allan

    2012-01-01

    Details are given of a visual photometer based on Joly's paraffin block apparatus of 1888. It is readily constructed from a couple of ordinary candles and a piece of aluminum foil, but enables two luminous sources to be compared to plus or minus 15-20%; this is much better than the eye alone can do. (Contains 1 figure.)

  7. The Sloan Digital Sky Survey-II: Photometry and Supernova Ia Light Curves from the 2005 Data

    SciTech Connect

    Holtzman, Jon A.; Marriner, John; Kessler, Richard; Sako, Masao; Dilday, Ben; Frieman, Joshua A.; Schneider, Donald P.; Bassett, Bruce; Becker, Andrew; Cinabro, David; DeJongh, Fritz; Depoy, Darren L.; Doi, Mamoru; Garnavich, Peter M.; Hogan, Craig J.; Jha, Saurabh; Konishi, Kohki; Lampeitl, Hubert; Marshall, Jennifer L.; McGinnis, David; Miknaitis, Gajus; /KICP, Chicago /Portsmouth U., ICG /Ohio State U., Dept. Astron. /Baltimore, Space Telescope Sci. /Johns Hopkins U. /Rochester Inst. Tech. /KIPAC, Menlo Park /Portsmouth U., ICG /Tokyo U., Inst. Astron. /South African Astron. Observ. /Cape Town U. /Tokyo U., ICRR /KIPAC, Menlo Park

    2010-08-26

    We present ugriz light curves for 146 spectroscopically confirmed or spectroscopically probable Type Ia supernovae from the 2005 season of the SDSS-II Supernova survey. The light curves have been constructed using a photometric technique that we call scene modeling, which is described in detail here; the major feature is that supernova brightnesses are extracted from a stack of images without spatial resampling or convolution of the image data. This procedure produces accurate photometry along with accurate estimates of the statistical uncertainty, and can be used to derive photometry taken with multiple telescopes. We discuss various tests of this technique that demonstrate its capabilities. We also describe the methodology used for the calibration of the photometry, and present calibrated magnitudes and fluxes for all of the spectroscopic SNe Ia from the 2005 season.

  8. VizieR Online Data Catalog: 1889-2015 photometry of Stingray nebula (Schaefer+, 2015)

    NASA Astrophysics Data System (ADS)

    Schaefer, B. E.; Edwards, Z. I.

    2016-02-01

    To get broad-band magnitudes for the Stingray, we have pulled from a wide variety of sources --the Harvard photographic plate collection from 1889 to 1989, the visual magnitude estimates of Albert Jones as archived by the American Association of Variable Star Observers (AAVSO) from 1994 to 2007, the All Sky Automated Survey (ASAS) from 2001 to 2009, the AAVSO telescopes going into the AAVSO Photometric All-sky Survey (APASS) from 2011 to 2015, plus our own photometry from CCD images with DECam on the Cerro Tololo 4-m Blanco telescope from 2014. We have added 15 mag from the literature or derived by us from the literature, all on six nights from 1969 to 1996. At our request, A. Henden has put the Stingray in the queue for time series photometry on the 0.61-m Optical Craftsmen Telescope at the Mount John Observatory in New Zealand. The 1-minute CCD integrations were through a Johnson V filter on the nights of 2015 March 23, 26, and 27. (1 data file).

  9. New Horizons disk-integrated approach photometry of Pluto and Charon

    NASA Astrophysics Data System (ADS)

    Zangari, Amanda M.; Buie, Marc W.; Buratti, Bonnie J.; Verbiscer, Anne J.; Howett, C. J. A.; Weaver, H. A.; Olkin, Catherine B.; Ennico, Kimberly; Young, Leslie A.; Stern, S. A.

    2015-11-01

    Approach and cruise observations of Pluto and Charon by NASA's New Horizons LOng Range Reconnaissance Imager ("LORRI") allow monitoring of Pluto not only at phase angles beyond Earth's 2 degree limit, but present a near constant sub-observer latitude of 43 degrees. However, the creation of light curves and solar phase curves of the pair prove to be an interesting challenge. Early images of the pair from July 2013 are barely resolved and have low signal, while later images show the pair clearly resolved and at sufficient resolution. Just at the Pluto approaches the signal level and image quality of prior HST images, surface features become resolved, rendering disk integrated photometry increasingly difficult and inaccurate, with the largest discrepancies found at longitudes which show the intersection of features informally named Tombaugh Regio ("the heart") and Cthulhu Macula ("the whale"). Now, post flyby, accurate knowledge of the radius and the shapes of surface features and their patterns of dark and light, allow for the creation of custom PSFs created from flyby maps. Using these maps, we present disk-integrated approach photometry, a solar phase curve and estimate Hapke parameters, taking into account the sub-observer position.This work was supported by the NASA New Horizons Project.

  10. ASTEROIDS IN GALEX: NEAR-ULTRAVIOLET PHOTOMETRY OF THE MAJOR TAXONOMIC GROUPS

    SciTech Connect

    Waszczak, Adam; Kulkarni, Shrinivas R.; Ofek, Eran O.

    2015-08-10

    We present ultraviolet (UV) photometry (near-UV (NUV) band, 180–280 nm) of 405 asteroids observed serendipitously by GALEX from 2003 to 2012. All asteroids in this sample were detected by GALEX at least twice. Unambiguous visible-color-based taxonomic labels (C type versus S type) exist for 315 of these asteroids; of these, thermal-infrared-based diameters are available for 245. We derive NUV − V color using two independent models to predict the visual magnitude V at each NUV-detection epoch. Both V models produce NUV − V distributions in which the S types are redder than C types with more than 8σ confidence. This confirms that the S types’ redder spectral slopes in the visible remain redder than the C types’ into the NUV, this redness being consistent with absorption by silica-containing rocks. The GALEX asteroid data confirm earlier results from the International Ultraviolet Explorer, which two decades ago produced the only other sizeable set of UV asteroid photometry. The GALEX-derived NUV − V data also agree with previously published Hubble Space Telescope (HST) UV observations of asteroids 21 Lutetia and 1 Ceres. Both the HST and GALEX data indicate that NUV band is less useful than u band for distinguishing subgroups within the greater population of visible-color-defined C types (notably, M types and G types)

  11. HERSCHEL FAR-INFRARED AND SUBMILLIMETER PHOTOMETRY FOR THE KINGFISH SAMPLE OF NEARBY GALAXIES

    SciTech Connect

    Dale, D. A.; Aniano, G.; Draine, B. T.; Engelbracht, C. W.; Hinz, J. L.; Montiel, E. J.; Krause, O.; Groves, B. A.; Roussel, H.; Appleton, P. N.; Armus, L.; Beirao, P.; Bolatto, A. D.; Brandl, B. R.; Calzetti, D.; Crocker, A. F.; Croxall, K. V.; Galametz, M.; Gordon, K. D.; Hao, C.-N.; and others

    2012-01-20

    New far-infrared and submillimeter photometry from the Herschel Space Observatory is presented for 61 nearby galaxies from the Key Insights on Nearby Galaxies: A Far-Infrared Survey with Herschel (KINGFISH) sample. The spatially integrated fluxes are largely consistent with expectations based on Spitzer far-infrared photometry and extrapolations to longer wavelengths using popular dust emission models. Dwarf irregular galaxies are notable exceptions, as already noted by other authors, as their 500 {mu}m emission shows evidence for a submillimeter excess. In addition, the fraction of dust heating attributed to intense radiation fields associated with photodissociation regions is found to be (21 {+-} 4)% larger when Herschel data are included in the analysis. Dust masses obtained from the dust emission models of Draine and Li are found to be on average nearly a factor of two higher than those based on single-temperature modified blackbodies, as single blackbody curves do not capture the full range of dust temperatures inherent to any galaxy. The discrepancy is largest for galaxies exhibiting the coolest far-infrared colors.

  12. Additional UBVRI and JHKL photometry of T Tauri stars in the Taurus region

    NASA Astrophysics Data System (ADS)

    Rydgren, A. E.; Vrba, F. J.

    1983-07-01

    We present nearly simultaneous UB VRI and JHKL photometry for 21 T Tauri stars in the Taurus region and three stars in northern Orion. Some nonsimultaneous UBVRJ and JHKL photometry of T Tauri stars in the Taurus and NGC 2264 regions is also given. These new data reinforce the conclusion from Rydgren, Schmelz, and Vrba (1982) that the T Tauri loci in the (J - H, H - K) and (H - K, K - L) diagrams are relatively narrow, implying a limited range in maximum temperature for the associated circumstellar dust. From an analysis of the available data for five actively variable T Tauri stars we find that (1) the slopes d (B - V )/d V and d (V - I)/dV differ significantly between stars, (2) the j - H, H - K, and K - L colors tend to become larger when the star is fainter at V, and (3) the amplitude of variations at L is much smaller than the amplitude at V. The resulting constraints on models for T Tauri variability are considered.

  13. VizieR Online Data Catalog: Far UV Stellar Photometry (Schmidt+ 1995)

    NASA Astrophysics Data System (ADS)

    Schmidt, E. G.; Carruthers, G. R.

    1995-07-01

    Far-ultraviolet photometry for 741 objects in a field in Sagittarius centered near M8 and 541 objects in a field centered near zeta Scorpii is presented. These data were extracted from electrographic images obtained with two cameras during a shuttle flight in 1991 April/May. The cameras provided band passes with lambda_eff = 1375 A and lambda_eff = 1781 A. Synthetic colors show that these bands are sensitive to effective temperature for hot stars. Our measurements were placed on a quantitative far-ultraviolet magnitude scale by convolving the spectra of stars observed by IUE with our cameras' spectral response functions. Fifty-eight percent of the ultraviolet objects were identified with visible stars using the SIMBAD database while another 40% of the objects are blends of early type stars too close together to separate with our resolution. Our photometry is compared with that from the TD-1, OAO 2, and ANS satellites and the S201 (Apollo 16) far-ultraviolet camera and found to agree at the level of a few tenths of a magnitude. Unlike previous studies, almost half of the identified visual counterparts to the ultraviolet objects are early B stars. A plot of distance modulus against ultraviolet color excess reveals a significant population of stars with strong ultraviolet excesses. (2 data files).

  14. ANALYSIS OF KEPLER'S SHORT-CADENCE PHOTOMETRY FOR TrES-2b

    SciTech Connect

    Kipping, David; Bakos, Gaspar

    2011-05-20

    We present an analysis of 18 short-cadence (SC) transit light curves of TrES-2b using quarter 0 (Q0) and quarter 1 (Q1) from the Kepler Mission. The photometry is of unprecedented precision, 237 ppm minute{sup -1}, allowing for the most accurate determination of the transit parameters yet obtained for this system. Global fits of the transit photometry, radial velocities, and known transit times are used to obtain a self-consistent set of refined parameters for this system, including updated stellar and planetary parameters. Special attention is paid to fitting for limb darkening and eccentricity. We place an upper limit on the occultation depth to be <72.9 ppm to 3{sigma} confidence, indicating TrES-2b has the lowest determined geometric albedo for an exoplanet, of A{sub g} < 0.146. We also produce a transit timing analysis using Kepler's SC data and demonstrate exceptional timing precision at the level of a few seconds for each transit event. With 18 fully sampled transits at such high precision, we are able to produce stringent constraints on the presence of perturbing planets, Trojans, and extrasolar moons. We introduce the novel use of control data to identify phasing effects. We also exclude the previously proposed hypotheses of short-period transit time variation and additional transits but find that the hypothesis of long-term inclination change is neither supported nor refuted by our analysis.

  15. THE CHANDRA SURVEY OF THE COSMOS FIELD. II. SOURCE DETECTION AND PHOTOMETRY

    SciTech Connect

    Puccetti, S.; Vignali, C.; Cappelluti, N.; Brunner, H.; Brusa, M.; Fruscione, A.; Finoguenov, A.; Fiore, F.; Zamorani, G.; Gilli, R.; Comastri, A.; Aldcroft, T. L.; Elvis, M.; Civano, F.; Miyaji, T.; Damiani, F.; Koekemoer, A. M.; Mainieri, V.

    2009-12-01

    The Chandra COSMOS Survey (C-COSMOS) is a large, 1.8 Ms, Chandra program that covers the central contiguous {approx}0.92 deg{sup 2} of the COSMOS field. C-COSMOS is the result of a complex tiling, with every position being observed in up to six overlapping pointings (four overlapping pointings in most of the central {approx}0.45 deg{sup 2} area with the best exposure, and two overlapping pointings in most of the surrounding area, covering an additional {approx}0.47 deg{sup 2}). Therefore, the full exploitation of the C-COSMOS data requires a dedicated and accurate analysis focused on three main issues: (1) maximizing the sensitivity when the point-spread function (PSF) changes strongly among different observations of the same source (from {approx}1 arcsec up to {approx}10 arcsec half-power radius); (2) resolving close pairs; and (3) obtaining the best source localization and count rate. We present here our treatment of four key analysis items: source detection, localization, photometry, and survey sensitivity. Our final procedure consists of a two step procedure: (1) a wavelet detection algorithm to find source candidates and (2) a maximum likelihood PSF fitting algorithm to evaluate the source count rates and the probability that each source candidate is a fluctuation of the background. We discuss the main characteristics of this procedure, which was the result of detailed comparisons between different detection algorithms and photometry tools, calibrated with extensive and dedicated simulations.

  16. Lightcurve, Color and Phase Function Photometry of the OSIRIS-REx Target Asteroid (101955) Bennu

    NASA Astrophysics Data System (ADS)

    Hergenrother, Carl W.; Nolan, Michael C.; Binzel, Richard P.; Cloutis, Edward A.; Barucci, Maria Antonietta; Michel, Patrick; Scheeres, Daniel J.; d'Aubigny, Christian Drouet; Lazzaro, Daniela; Pinilla-Alonso, Noemi; Campins, Humberto; Licandro, Javier; Clark, Beth E.; Rizk, Bashar; Beshore, Edward C.; Lauretta, Dante S.

    2013-09-01

    The NASA OSIRIS-REx mission will retrieve a sample of the carbonaceous near-Earth Asteroid (101955) Bennu and return it to Earth in 2023. Photometry in the Eight Color Asteroid Survey (ECAS) filter system and Johnson-Cousins V and R filters were conducted during the two most recent apparitions in 2005/2006 and 2011/2012. Lightcurve observations over the nights of September 14-17, 2005 yielded a synodic rotation period of 4.2905 ± 0.0065 h, which is consistent with the results of Nolan et al. (2013). ECAS color measurements made during the same nights confirm the B-type classification of Clark et al. (Clark, B.E., Binzel, R.P., Howell, E.S., Cloutis, E.A., Ockert-Bell, M., Christensen, P., Barucci, M.A., DeMeo, F., Lauretta, D.S., Connolly, H., Soderberg, A., Hergenrother, C., Lim, L., Emery, J., Mueller, M. [2011]. Icarus 216, 462-475). A search for the 0.7 μm hydration feature using the method of Vilas (Vilas, F. [1994]. Icarus 111, 456-467) did not reveal its presence. Photometry was obtained over a range of phase angles from 15° to 96° between 2005 and 2012. The resulting phase function slope of 0.040 magnitudes per degree is consistent with the phase slopes of other low albedo near-Earth asteroids (Belskaya, I.N., Shevchenko, V.G. [2000]. Icarus 147, 94-105).

  17. Probing the physics of bright supernovae with high-cadence photometry

    NASA Astrophysics Data System (ADS)

    Bonanos, Alceste; Boumis, Panos

    2016-06-01

    We propose high-cadence photometry as a tool to probe the physics of both thermonuclear and core-collapse supernova explosions. We demonstrate the idea by conducting high-cadence monitoring of theoptical light curve of the nearby, Type Ia SN 2014J in M82. B and V-band photometry on days 15‑18 after tmax(B) was obtained with a cadence of 2 min per band, using the 2.3 m Aristarchos telescope, at Helmos Observatory, Greece. The data reveal evidence for rapid variability at the 0.02‑0.05 mag level on timescales of 15‑60 min on all four nights. The rapid variability could be due to one or a combination of the following scenarios: the clumpiness of the ejecta, their interaction with circumstellar material, the asymmetry of the explosion, or the mechanism causing the secondary maximum in the near-infrared lightcurve. We present our plans to use the new Prime Focus Instrument with its fast-frame sCMOS cameras on the Kryoneri 1.2 m telescope in Greece, constructed as part of ESA's lunar monitoring project NELIOTA, to systematically monitor bright supernovae for rapid variability.

  18. VizieR Online Data Catalog: IC 4651 uvby photometry (Meibom, 2000)

    NASA Astrophysics Data System (ADS)

    Meibom, S.

    2000-08-01

    New accurate CCD photometry in the u, v, b and y bands of the Stroemgren system filters has been obtained for 17640 stars to approximately. V=20mag in a approximately 21' x 21' field centered on the intermediate-age open cluster IC 4651. The observations was obtained with the Danish 1.5-m telescope at the European Southern Observatory, La Silla, Chile. Table 1 contains information about the Date, Night, Filter, Exposure time, Airmass, CCD rotation angle, and RA- , DE-offsets for all 89 frames. Table 2 gives cross-references between the MEI-system (this paper) and the Lindoff (1972A&AS....7..231L, IC 4651 NNN), Eggen (1971ApJ...166...87E, Cl* IC 4651 Egg NN), Anthony-Twarog & Twarog (1987AJ.....94.1222A, Cl* IC 4651 AT 1-NNN, Cl* IC 4651 AT 2-NN), and Anthony-Twarog et al. (1988AJ.....95.1453A, Cl* IC 4651 AMC I-NNN, Cl* IC 4651 AMC NNNN) identification numbers. Table 3 is the final catalogue of the new Stroemgren uvby photometry, ordered by MEI identification number. For each star, it gives the MEI number, Global CCD x- and y-coordinates, J2000 coordinates , the new y, b, v, and u magnitudes on the standard system, number of detections of the individual stars, and their mean errors. (3 data files).

  19. BVRI CCD-Photometry of comparison stars in the fields of galaxies with active nuclei. V

    NASA Astrophysics Data System (ADS)

    Doroshenko, V. T.; Sergeev, S. G.; Efimov, Yu. S.; Borman, G. A.; Okhmat, D. N.; Pulatova, N. G.; Nazarov, S. V.

    2013-09-01

    Observations of 79 comparison stars in the fields of seven Seyfert galaxies (Akn 79, Mrk 374, Mrk 382, Mrk 478, Mrk 493, Mrk 618, and Mrk 1513) and a single quasar (CTA 102) are reported. The observations were made with CCD photometry in the B, V, R, and I bands. The stellar magnitudes of these stars in the V band range from 12m.9 to 18m.4. The typical photometric uncertainties for magnitude 15 stars are 0m.008, 0m.011, 0m.009 and 0m.015 in the BVRI bands, respectively. For most of these stars the B, V, R, and I magnitudes have not been known previously. A variable star with brightness variations over a period of P = 0.1705 d was found in the field of the galaxy Mrk 478 and the sampled stars in the field of the galaxy Mrk 1513 include a variable with a period of P = 0.2211 d. These stars may be type W UMa contact binary systems with orbital periods of 0.341 and 0.4422 d, respectively. Finding charts for the comparison stars are included. These results can be used for differential photometry of the AGNs.

  20. Recovering Astrophysical Signals of Background Variable Sources in Kepler Data by Means of Custom Aperture Photometry

    NASA Astrophysics Data System (ADS)

    Bowers, Rebecca Lyn; Pepper, Joshua; Prsa, Andrej

    2016-01-01

    Originally designed for exoplanet discovery, the NASA Kepler mission conducted long-baseline observations of hundreds of thousands of stars, providing a wealth of high-precision photometric data useful for a wide variety of scientific investigations (multiple stellar systems, long-period variables, asteroseismology, etc.). By examining astrophysical targets in the Kepler data set and performing pixel-level data analysis and custom aperture photometry, we seek to identify contaminating astrophysical sources of variability. We are using our own customized suite of Python programs to perform photometry, visualization, data reduction, and differential image analysis, all of which will aid us in determining whether the variability identified in the released Kepler light curves is a result of true variation in the target stars (i.e. eclipsing binaries, pulsating variables, etc.) or if the photometric signals have been contaminated by the presence of background astrophysical sources. In the case of the latter, we obtain optimized light curves for the background variables using the custom apertures.

  1. RGB color photometry of the solar corona from total solar eclipses

    NASA Astrophysics Data System (ADS)

    Shopov, Y. Y.; Varonov, A.; Stoykova, D. A.

    2016-02-01

    In the following article we present some of our results from observations of two total solar eclipses (TSE). By combining appropriate photographic equipment and post-processing techniques we show that numerous solar phenomena can be captured in details during TSE. We use color slide RGB photometry technique to visualize invisible regions of the solar corona and to highlight some of the solar phenomena that are very difficult for observation by Earth-based observatories. In fact it reveals more details of the far solar corona than any original image taken from ground-based observations. RGB photometry visualizes different components of the solar corona in one image, which is impossible using conventional observations. This makes it valuable tool for studies of the solar corona. Here we first observe peculiar near infrared emission regions around the upper part of the solar limb during the 1999 TSE. So far its origin is unknown and they need further studies including observations during other solar eclipses. Our observational experiment was designed for other purposes and their registration was completely unexpected.

  2. The Very Low Albedo of an Extrasolar Planet: MOST Space-based Photometry of HD 209458

    NASA Astrophysics Data System (ADS)

    Rowe, Jason F.; Matthews, Jaymie M.; Seager, Sara; Miller-Ricci, Eliza; Sasselov, Dimitar; Kuschnig, Rainer; Guenther, David B.; Moffat, Anthony F. J.; Rucinski, Slavek M.; Walker, Gordon A. H.; Weiss, Werner W.

    2008-12-01

    Measuring the albedo of an extrasolar planet provides insight into its atmospheric composition and its global thermal properties, including heat dissipation and weather patterns. Such a measurement requires very precise photometry of a transiting system, fully sampling many phases of the secondary eclipse. Space-based optical photometry of the transiting system HD 209458 from the MOST (Microvariablity and Oscillations of Stars) satellite, spanning 14 and 44 days in 2004 and 2005, respectively, allows us to set a sensitive limit on the optical eclipse of the hot exosolar giant planet in this system. Our best fit to the observations yields a flux ratio of the planet and star of 7 +/- 9 ppm (parts per million), which corresponds to a geometric albedo through the MOST bandpass (400-700 nm) of Ag = 0.038 +/- 0.045. This gives a 1 σ upper limit of 0.08 for the geometric albedo and a 3 σ upper limit of 0.17. HD 209458b is significantly less reflective than Jupiter (for which Ag would be about 0.5). This low geometric albedo rules out the presence of bright reflective clouds in this exoplanet's atmosphere. We determine refined parameters for the star and exoplanet in the HD 209458 system based on a model fit to the MOST light curve. MOST is a Canadian Space Agency mission, operated jointly by Dynacon, Inc., and the Universities of Toronto and British Columbia, with assistance from the University of Vienna.

  3. Pulsations of the Oe Star ζ Ophiuchi from MOST Satellite Photometry and Ground-based Spectroscopy

    NASA Astrophysics Data System (ADS)

    Walker, G. A. H.; Kuschnig, R.; Matthews, J. M.; Reegen, P.; Kallinger, T.; Kambe, E.; Saio, H.; Harmanec, P.; Guenther, D. B.; Moffat, A. F. J.; Rucinski, S. M.; Sasselov, D.; Weiss, W. W.; Bohlender, D. A.; Božić, H.; Hashimoto, O.; Koubský, P.; Mann, R.; Ruždjak, D.; Škoda, P.; Šlechta, M.; Sudar, D.; Wolf, M.; Yang, S.

    2005-04-01

    Twenty-four days of highly precise Microvariability and Oscillations of Stars (MOST) satellite photometry obtained in mid-2004 of the rapidly rotating O9.5 V star ζ Oph have yielded at least a dozen significant oscillation frequencies between 1 and 10 cycles day-1, clearly indicating its relationship to β Cephei variables. Eight periods were found in He I λ4922 and Hβ line profile variations (LPV) of which six coincide with those from the MOST photometry. This unique photometric and spectroscopic detection of radial and nonradial pulsations leads to a plausible model in which high l-modes are excited when their frequencies in the corotating frame are similar to those of low-order radial modes. We propose that the dominant photometric 4.6 hr period (f1) corresponds to a radial first overtone excited by the κ-mechanism associated with the Fe opacity bump. No unambiguous rotational period can be identified in either the light curve or the LPV. A Canadian Space Agency mission, jointly operated by Dynacon Inc., the University of Toronto Institute of Aerospace Studies, and the University of British Columbia with the assistance of the University of Vienna.

  4. Spitzer IRAC mid-infrared photometry of 500-750 brown dwarf

    SciTech Connect

    Saumon, Didier; Leggett, Sandy K; Albert, Loic; Artigau, Etienne; Burningham, Ben; Delfosse, Xavier; Delorme, Philippe; Forveille, Thierry; Lucas, Philip W; Marley, Mark S; Pinfield, David J; Reyle, Celine; Smart, Richard L; Warren, Stephen J

    2010-10-26

    Mid-infrared data, including Spitzer warm-IRAC [3.6] and [4.5] photometry, is critical for understanding the cold population of brown dwarfs now being found, objects which have more in common with planets than stars. As effective temperature (T{sub eff}) drops from 800K to 400K, the fraction of flux emitted beyond 3 {mu}m increases rapidly, from about 40% to > 75%. This rapid increase makes a color like H-[4.5] a very sensitive temperature indicator, and it can be combined with a gravity- and metallicity-sensitive color like H-K to constrain all three of these fundamental properties, which in turn gives us mass and age for these slowly cooling objects. Determination of mid-infrared color trends also allows better exploitation of the WISE mission by the community. We use new Spitzer Cycle 6 IRAC photometry, together with published data, to present trends of color with type for L0 to T10 dwarfs. We also use the atmospheric and evolutionary models of Saumon and Marley to investigate the masses and ages of 13 very late-type T dwarfs, which have H-[4.5] > 3.2 and T{sub eff} {approx} 500K to 750K.

  5. WIDE-FIELD MULTIBAND PHOTOMETRY OF GLOBULAR CLUSTER SYSTEMS IN THE FORNAX GALAXY CLUSTER

    SciTech Connect

    Kim, Hak-Sub; Yoon, Suk-Jin; Chung, Chul; Lee, Sang-Yoon; Lee, Young-Wook; Sohn, Sangmo Tony; Kim, Sang Chul; Kim, Eunhyeuk

    2013-01-20

    We present wide-field multiband photometry of globular cluster (GC) systems in NGC 1399, NGC 1404, and NGC 1387 located in the central region of the Fornax galaxy cluster. Observation was carried out through U, B, V, and I bands, which marks one of the widest and deepest U-band studies on extragalactic GC systems. The present U-band photometry enables us to significantly reduce the contamination by a factor of two for faint sources (V {sub 0} {approx} 23.5). The main results based on some 2000 GC candidates around NGC 1399, NGC 1404, and NGC 1387 are as follows: (1) the GC system in each galaxy exhibits bimodal color distributions in all colors examined, but the shape of color histograms varies systematically depending on colors; (2) NGC 1399 shows that the mean colors of both blue and red GCs become bluer with increasing galactocentric radius; (3) NGC 1399 shows overabundance of GCs in the directions of NGC 1404 and NGC 1387, indicating their ongoing interactions; and (4) NGC 1399 also exhibits a {approx}0.'5 offset between the center of the inner GC distribution and the galaxy's optical center, suggesting that NGC 1399 is not yet dynamically relaxed and may be undergoing merger events.

  6. T-PHOT: PSF-matched, prior-based, multiwavelength extragalactic deconfusion photometry

    NASA Astrophysics Data System (ADS)

    Merlin, E.; Fontana, A.; Ferguson, H. C.; Dunlop, J. S.; Elbaz, D.; Bourne, N.; Bruce, V. A.; Buitrago, F.; Castellano, M.; Schreiber, C.; Grazian, A.; McLure, R. J.; Okumura, K.; Shu, X.; Wang, T.; Amorín, R.; Boutsia, K.; Cappelluti, N.; Comastri, A.; Derriere, S.; Faber, S. M.; Santini, P.

    2016-09-01

    T-PHOT extracts accurate photometry from low-resolution images of extragalactic fields, where the blending of sources can be a serious problem for accurate and unbiased measurement of fluxes and colors. It gathers data from a high-resolution image of a region of the sky and uses the source positions and morphologies to obtain priors for the photometric analysis of the lower resolution image of the same field. T-PHOT handles different types of datasets as input priors, including a list of objects that will be used to obtain cutouts from the real high-resolution image, a set of analytical models (as .fits stamps), and a list of unresolved, point-like sources, useful for example for far-infrared wavelength domains. T-PHOT yields accurate estimations of fluxes within the intrinsic uncertainties of the method when systematic errors are taken into account (which can be done using a flagging code given in the output), and handles multiwavelength optical to far-infrared image photometry. T-PHOT was developed as part of the ASTRODEEP project (www.astrodeep.eu).

  7. A laboratory module on radiometry, photometry and colorimetry for an undergraduate optics course

    NASA Astrophysics Data System (ADS)

    Polak, Robert D.

    2014-07-01

    The bachelor's degree in Physics at Loyola University Chicago requires both an upper-division course in Optics as well as a companion Optics Laboratory course. Recently, the laboratory course has undergone dramatic changes. Traditional weekly laboratories have been replaced with three laboratory modules, where students focus on a single topic over several weeks after which the students submit a laboratory report written in the style of a journal article following American Institute of Physics style manual. With this method, students are able to gain a deeper understanding of the specific topic areas of radiometry, photometry and colorimetry, lens design and aberrations, and polarization and interference while using industry-standard equipment and simulation software. In particular, this work will provide the details of the laboratory module on radiometry, photometry and colorimetry where students use a photoradiometer and integrating sphere to characterize the optical properties of an LCD monitor, light bulb and a fiber optic light source calculating properties such as luminous flux, luminous intensity, luminance, CIE color coordinates, NTSC ratio, color temperature and luminous efficacy.

  8. THE MASSIVE STAR POPULATION IN M101. III. SPECTRA AND PHOTOMETRY OF THE LUMINOUS AND VARIABLE STARS

    SciTech Connect

    Grammer, Skyler H.; Humphreys, Roberta M.; Gerke, Jill E-mail: roberta@umn.edu

    2015-05-15

    We discuss moderate-resolution spectra, multicolor photometry, and light curves of 31 of the most luminous stars and variables in the giant spiral M101. The majority are intermediate A- to F-type supergiants. We present new photometry and light curves for three known “irregular blue variables,” V2, V4, and V9, and identify a new candidate. Their spectra and variability confirm that they are luminous blue variable (LBV) candidates and V9 may be in an LBV-like maximum light state or eruption.

  9. IDENTIFICATION OF A WIDE, LOW-MASS MULTIPLE SYSTEM CONTAINING THE BROWN DWARF 2MASS J0850359+105716

    SciTech Connect

    Faherty, Jacqueline K.; Burgasser, Adam J.; Bochanski, John J.; Looper, Dagny L.; West, Andrew A.; Van der Bliek, Nicole S.

    2011-03-15

    We report our discovery of NLTT 20346 as an M5+M6 companion system to the tight binary (or triple) L dwarf 2MASS J0850359+105716. This nearby ({approx}31 pc), widely separated ({approx}7700 AU) quadruple system was identified through a cross-match of proper motion catalogs. Follow-up imaging and spectroscopy of NLTT 20346 revealed it to be a magnetically active M5+M6 binary with components separated by {approx}2'' (50-80 AU). Optical spectroscopy of the components shows only moderate H{alpha} emission corresponding to a statistical age of {approx}5-7 Gyr for both M dwarfs. However, NLTT 20346 is associated with the XMM-Newton source J085018.9+105644, and based on X-ray activity the age of NLTT 20346 is between 250 and 450 Myr. Strong Li absorption in the optical spectrum of 2MASS J0850+1057 indicates an upper age limit of 0.8-1.5 Gyr, favoring the younger age for the primary. Using evolutionary models in combination with an adopted system age of 0.25-1.5 Gyr indicates a total mass for 2MASS J0850+1057 of 0.07 {+-} 0.02 M{sub sun}, if it is a binary. NLTT 20346/2MASS J0850+1057 joins a growing list of hierarchical systems containing brown dwarf binaries and is among the lowest binding energy associations found in the field. Formation simulations via gravitational fragmentation of massive extended disks have successfully produced a specific analog to this system.

  10. REVIEW ARTICLE: Photometry, radiometry and 'the candela': evolution in the classical and quantum world

    NASA Astrophysics Data System (ADS)

    Zwinkels, Joanne C.; Ikonen, Erkki; Fox, Nigel P.; Ulm, Gerhard; Rastello, Maria Luisa

    2010-10-01

    The metrological fields of photometry and radiometry and their associated units are closely linked through the current definition of the base unit of luminous intensity—the candela. These fields are important to a wide range of applications requiring precise and accurate measurements of electromagnetic radiation and, in particular, the amount of radiant energy (light) that is perceived by the human eye. The candela has been one of the base units since the inception of the International System of Units (SI) and is the only base unit that quantifies a fundamental biological process—human vision. This photobiological process spans an enormous dynamic range of light levels from a few-photon interaction involved in triggering the vision mechanism to a level of more than 1015 photons per second that is accommodated by the visual response under bright daylight conditions. This position paper, prepared by members of the Task Group on the SI of the Consultative Committee for Photometry and Radiometry Strategic Planning Working Group (CCPR WG-SP), reviews the evolution of these fields of optical radiation measurements and their consequent impact on definitions and realization of the candela. Over the past several decades, there have been significant developments in sources, detectors, measuring instruments and techniques, that have improved the measurement of photometric and radiometric quantities for classical applications in lighting design, manufacturing and quality control processes involving optical sources, detectors and materials. These improved realizations largely underpin the present (1979) definition of the candela. There is no consensus on whether this radiant-based definition fully satisfies the current and projected needs of the optical radiation community. There is also no consensus on whether a reformulation of the definition of the candela in terms of photon flux will be applicable to the lighting community. However, there have been significant recent

  11. Multicolor photometry of the merging galaxy cluster A2319: Dynamics and star formation properties

    SciTech Connect

    Yan, Peng-Fei; Yuan, Qi-Rong; Zhang, Li; Zhou, Xu E-mail: yuanqirong@njnu.edu.cn

    2014-05-01

    Asymmetric X-ray emission and a powerful cluster-scale radio halo indicate that A2319 is a merging cluster of galaxies. This paper presents our multicolor photometry for A2319 with 15 optical intermediate filters in the Beijing-Arizona-Taiwan-Connecticut (BATC) system. There are 142 galaxies with known spectroscopic redshifts within the viewing field of 58' × 58' centered on this rich cluster, including 128 member galaxies (called sample I). A large velocity dispersion in the rest frame, 1622{sub −70}{sup +91} km s{sup –1}, suggests merger dynamics in A2319. The contour map of projected density and localized velocity structure confirm the so-called A2319B substructure, at ∼10' northwest to the main concentration A2319A. The spectral energy distributions (SEDs) of more than 30,000 sources are obtained in our BATC photometry down to V ∼ 20 mag. A u-band (∼3551 Å) image with better seeing and spatial resolution, obtained with the Bok 2.3 m telescope at Kitt Peak, is taken to make star-galaxy separation and distinguish the overlapping contamination in the BATC aperture photometry. With color-color diagrams and photometric redshift technique, 233 galaxies brighter than h {sub BATC} = 19.0 are newly selected as member candidates after an exclusion of false candidates with contaminated BATC SEDs by eyeball-checking the u-band Bok image. The early-type galaxies are found to follow a tight color-magnitude correlation. Based on sample I and the enlarged sample of member galaxies (called sample II), subcluster A2319B is confirmed. The star formation properties of cluster galaxies are derived with the evolutionary synthesis model, PEGASE, assuming a Salpeter initial mass function and an exponentially decreasing star formation rate (SFR). A strong environmental effect on star formation histories is found in the manner that galaxies in the sparse regions have various star formation histories, while galaxies in the dense regions are found to have shorter SFR time

  12. Accurate PSF-matched photometry for the J-PAS survey

    NASA Astrophysics Data System (ADS)

    Jimenez-Teja, Yolanda; Benitez, Txitxo; Dupke, Renato a.

    2015-08-01

    The Javalambre-PAU Astrophysical Survey (J-PAS) is expected to map 8,600 squared-degrees of the sky using 54 narrow and 5 broad band filters. Carried out by a Spanish-Brazilian consortium, the main goal of this survey is to measure Baryon Acoustic Oscillations (BAOs) with photometric redshifts. The expectation is measuring these photometric redshifts with a precision of dz/(1 + z) ~ 0.003 for 100 million galaxies and a few millions of quasars, and reaching an accuracy of dz/(1 + z) ~ 0.01 for other 300 million galaxies. With these numbers, it will be possible to determine w in the Dark Energy (DE) equation of state with an accuracy of < 4%. To achieve such precision and measure the radial BAOs, not only an advanced technical setup but also special data processing tools are required. These tools must be accurate as well as suitable to be implemented in fully automated and computationally efficient algorithms.The factor that most influences the photometric redshift precision is the quality of the photometry. For that reason we have developed a new technique based on the Chebyshev-Fourier bases (CHEFs, Jiménez-Teja & Benítez 2012, ApJ, 745, 150) to obtain a highly precise multicolor photometry without PSF consideration, thus saving a considerable amount of time and circumventing severe problems such as the PSF variability across the images. The CHEFs are a set of mathematical orthonormal bases with different scale and resolution levels, originally designed to fit the surface light distribution of galaxies. They have proved to be able to model any kind of morphology, including spirals, highly elliptical, or irregular galaxies, including isophotal twists and fine substructure. They also fit high signal-to-noise images, lensing arcs and stars with great accuracy. We can calculate optimal, unbiased, total magnitudes directly through these CHEFs models and, thus, colors without needing the PSF.We compare our photometry with widely-used codes such as SExtractor (Bertin

  13. NEAR-INFRARED PHOTOMETRY OF Y DWARFS: LOW AMMONIA ABUNDANCE AND THE ONSET OF WATER CLOUDS

    SciTech Connect

    Leggett, S. K.; Morley, Caroline V.; Marley, M. S.; Saumon, D.

    2015-01-20

    We present new near-infrared photometry for seven late-type T dwarfs and nine Y-type dwarfs, and lower limit magnitudes for a tenth Y dwarf, obtained at Gemini Observatory. We also present a reanalysis of H-band imaging data from the Keck Observatory Archive, for an 11th Y dwarf. These data are combined with earlier MKO-system photometry, Spitzer and WISE mid-infrared photometry, and available trigonometric parallaxes, to create a sample of late-type brown dwarfs that includes 10 T9-T9.5 dwarfs or dwarf systems, and 16 Y dwarfs. We compare the data to our models, which include updated H{sub 2} and NH{sub 3} opacity, as well as low-temperature condensate clouds. The models qualitatively reproduce the trends seen in the observed colors; however, there are discrepancies of around a factor of two in flux for the Y0-Y1 dwarfs, with T {sub eff} ≈ 350-400 K. At T {sub eff} ∼ 400 K, the problems could be addressed by significantly reducing the NH{sub 3} absorption, for example by halving the abundance of NH{sub 3} possibly by vertical mixing. At T {sub eff} ∼ 350 K, the discrepancy may be resolved by incorporating thick water clouds. The onset of these clouds might occur over a narrow range in T {sub eff}, as indicated by the observed small change in 5 μm flux over a large change in J – W2 color. Of the known Y dwarfs, the reddest in J –W2 are WISEP J182831.08+265037.8 and WISE J085510.83–071442.5. We interpret the former as a pair of identical 300-350 K dwarfs, and the latter as a 250 K dwarf. If these objects are ∼3 Gyr old, their masses are ∼10 and ∼5 Jupiter-masses, respectively.

  14. VizieR Online Data Catalog: VRI photometry in NGC 7129 (Dahm+, 2015)

    NASA Astrophysics Data System (ADS)

    Dahm, S. E.; Hillenbrand, L. A.

    2015-06-01

    Three epochs of optical imaging data were obtained of the NGC 7129 region between 1993 and 1999. The first and most extensive survey consisted of VRCIC-band CCD imaging obtained using the T2KA CCD at the Kitt Peak National Observatory (KPNO) 0.9m telescope in 1993 June by LAH and S. Strom. The T2KA detector is a 2048*2048 CCD with 24μm pixels yielding a platescale of 0.69pixel-1. The complete list of all ~2500 sources from the T2KA CCD imaging survey of NGC 7129 including J2000 coordinates, optical (V, V-RC, and RC-IC) photometry, and associated photometric errors is provided in Table 4. The second epoch of RCIC-band photometry was obtained using the Low Resolution Imaging Spectrograph (LRIS) on Keck II in 1999 June by LAH. Finally BVRCIC photometry of the NGC 7129 region was obtained in 1999 October at the f/10 focus of the University of Hawaii (UH) 2.2m telescope on Mauna Kea by G. H. Herbig. The detector was a Tektronix 2048*2048 CCD with 24μm pixels. The field was imaged in all filters during photometric conditions and in average seeing conditions for Mauna Kea, 0.75". The plate scale was 0.22pixel-1, and the imaged field was approximately 7.5'*7.5' in area. The Hα emission survey of NGC 7129 was carried out on 10 October 2003 by SED using the Wide-Field Grism Spectrograph (WFGS) installed at the f/10 Cassegrain focus of the University of Hawaii 2.2m telescope. A 420 line mm-1 grism blazed at 6400Å yielded a dispersion of 3.85Å/pixel. The narrowband Hα filter isolated a region of the first-order spectra between ~6300 and 6750Å. The WFGS imaged upon the central 1024*1024 pixels of a Tektronix 2048*2048 pixel CCD, yielding a nominal field of view ~5.5'*5.5'. The WFGS survey covered a region of about 150 arcmin2, roughly centered upon LkHα 234. Low-dispersion spectra were obtained using HYDRA on WIYN in 1993 and the RC Spectrograph on the Mayall 4m telescope in 1994 by LAH. (4 data files).

  15. A catalog of K giants at the South Galactic Pole - Broadband and DDO photometry and radial velocities

    NASA Astrophysics Data System (ADS)

    Flynn, C.; Freeman, K. C.

    1993-03-01

    We describe a sample of K giants at the South Galactic Pole, selected to examine the chemical and kinematical properties of stars perpendicular to the galactic plane and to measure the local column density of the disk. We report velocities, abundances, absolute magnitudes, and broadband BV photometry for over 500 giants.

  16. New BVI {sub C} photometry of low-mass pleiades stars: Exploring the effects of rotation on broadband colors

    SciTech Connect

    Kamai, Brittany L.; Stassun, Keivan G.; Vrba, Frederick J.; Stauffer, John R.

    2014-08-01

    We present new BVI{sub C} photometry for 350 Pleiades proper motion members with 9 < V ≲ 17. Importantly, our new catalog includes a large number of K- and early M-type stars, roughly doubling the number of low-mass stars with well-calibrated Johnson/Cousins photometry in this benchmark cluster. We combine our new photometry with existing photometry from the literature to define a purely empirical isochrone at Pleiades age (≈100 Myr) extending from V = 9 to 17. We use the empirical isochrone to identify 48 new probable binaries and 14 likely nonmembers. The photometrically identified single stars are compared against their expected positions in the color-magnitude diagram (CMD). At 100 Myr, the mid K and early M stars are predicted to lie above the zero-age main sequence (ZAMS) having not yet reached the ZAMS. We find in the B – V versus V CMD that mid K and early M dwarfs are instead displaced below (or blueward of) the ZAMS. Using the stars' previously reported rotation periods, we find a highly statistically significant correlation between rotation period and CMD displacement, in the sense that the more rapidly rotating stars have the largest displacements in the B – V CMD.

  17. VizieR Online Data Catalog: UBVI CCD photometry of Carina region stars (Molina-Lera+, 2016)

    NASA Astrophysics Data System (ADS)

    Molina-Lera, J. A.; Baume, G.; Gamen, R.; Costa, E.; Carraro, G.

    2016-08-01

    Photometric parameters for 62730 stars in the carina region covering 6 stellar clusters (NGC 3752, Trumpler 18, NGC 3590, Hogg 10, 11 and 12) and the surrounding field. The photometry was secured in March 2006 and March 2009 with the Y4KCAM camera attached to the Cerro Tololo Inter American Observatory (CTIO, Chile) 1.0-m telescope. (1 data file).

  18. Photometric calibration of NGS/POSS and ESO/SRC plates using the NOAO PDS measuring engine. I - Stellar photometry

    NASA Technical Reports Server (NTRS)

    Cutri, Roc M.; Low, Frank J.; Marvel, Kevin B.

    1992-01-01

    The PDS/Monet measuring engine at the National Optical Astronomy Observatory was used to obtain photometry of nearly 10,000 stars on the NGS/POSS and 2000 stars on the ESO/SRC Survey glass plates. These measurements have been used to show that global transformation functions exist that allow calibration of stellar photometry from any blue or red plate to equivalent Johnson B and Cousins R photoelectric magnitudes. The four transformation functions appropriate for the POSS O and E and ESO/SRC J and R plates were characterized, and it was found that, within the measurement uncertainties, they vary from plate to plate only by photometric zero-point offsets. A method is described to correct for the zero-point shifts and to obtain calibrated B and R photometry of stellar sources to an average accuracy of 0.3-0.4 mag within the range R between values of 8 and 19.5 for red plates in both surveys, B between values of 9 and 20.5 on POSS blue plates, and B between values of 10 and 20.5 on ESO/SRC blue plates. This calibration procedure makes it possible to obtain rapid photometry of very large numbers of stellar sources.

  19. Karl Schwarzschild's investigations of `out-of-focus photometry' between 1897 and 1899 at Kuffner Observatory in Vienna

    NASA Astrophysics Data System (ADS)

    Habison, Peter

    From 1897 to 1899 Karl Schwarzschild worked at the Kuffner Observatory in Vienna. During these years he developed new measuring techniques in the field of photographic photometry, where he studied particularly the quantitative determination of the departure from the reciprocity law during photographic exposure. This paper concentrates on Schwarzschild's early work in this field and gives an overview of his important Viennese years.

  20. The study of comets, part 1. [conference on photometry and spectrum analysis of Kohoutek comet and comet tails

    NASA Technical Reports Server (NTRS)

    Donn, B. (Editor); Mumma, M. J. (Editor); Jackson, W. M. (Editor); Ahearn, M. (Editor); Harrington, R. (Editor)

    1976-01-01

    Papers are presented dealing with observations of comets. Topic discussed include: photometry, polarimetry, and astrometry of comets; detection of water and molecular transitions in comets; ion motions in comet tails; determination of comet brightness and luminosity; and evolution of cometary orbits. Emphasis is placed on analysis of observations of comet Kohoutek.

  1. Developments of Si-PIN detectors for Continuous Spectro-photometry of Black Holes (CSPOB)

    SciTech Connect

    Bhoumik, Debashis; Mondal, Shyamal; Chakrabarti, S. K.

    2008-10-08

    The goal of the proposed small-satellite mission named Continuous Spectro-Photometry of Black holes (CSPOB) is to observe a given galactic black hole candidate for several months continuously or almost continuously. In the former case, two identical satellites are required, while one satellite is sufficient if we employ one satellite. Such an observation from 0.5keV to 30keV should answer several questions regarding the spectral and timing properties of accretion processes. In particular, on the origin of the sub-Keplerian component of the accretion flow which is observed in many black hole candidates. We present preliminary results on the development of X-ray detectors based on Hamamatsu made Si-PIN Photodiodes at our laboratory.

  2. VizieR Online Data Catalog: uvbyCaHβ photometry of NGC 752 (Twarog+, 2015)

    NASA Astrophysics Data System (ADS)

    Twarog, B. A.; Anthony-Twarog, B. J.; Deliyannis, C. P.; Thomas, D. T.

    2016-04-01

    Intermediate and narrow-band images of NGC752 were obtained using the WIYN 0.9m telescope during three observing runs in 2010 November, 2012 November and 2013 December. For the first two observing runs, the S2KB CCD was used at the f/7.5 focus of the telescope for a 20'*20' field with 0.6'' pixels. All seven filters were from the 3''*3'' filter set owned jointly by the University of Kansas and Mt. Laguna Observatory. For the 2013 December run, the telescope was equipped with the Half-Degree-Imager (HDI), a 4K*4K chip with a 29'*29' field with 0.43'' pixels. The seven filters were from the extended Stromgren set recently acquired for specific use with the HDI. Final photometry on the uvbyCaHβ system can be found in Table4. (1 data file).

  3. CCD Photometry of Six Asteroids from the Universidad de Monterry Observatory

    NASA Astrophysics Data System (ADS)

    Sada, Pedro V.

    2008-09-01

    CCD photometry of six asteroids was obtained at the Universidad de Monterrey Observatory during January and February 2008. The resulting synodic rotation periods and amplitudes are as follows: 1292 Luce, 6.9541 ± 0.0002 h, 0.20 ± 0.01 mag; 1303 Luthera, 5.878 ± 0.003 h, 0.08 ± 0.01 mag; 1900 Katyusha, 9.4999 ± 0.0001 h, 0.72 ± 0.02 mag, 2807 Karl Marx, 8.842 ± 0.001 h, 0.40 ± 0.05 mag; 3409 Abramov, 7.791 ± 0.002 h, 0.55 ± 0.02 mag; and 9117 Aude, 2.8156 ± 0.0001 h, 0.20 ± 0.01 mag.

  4. A Search for Planetary Transits of the Star HD 187123 by Spot Filter CCD Differential Photometry

    NASA Technical Reports Server (NTRS)

    Castellano, T.; DeVincenzi, D. (Technical Monitor)

    2000-01-01

    A novel method for performing high precision, time series CCD differential photometry of bright stars using a spot filter, is demonstrated. Results for several nights of observing of the 51 Pegasi b-type planet bearing star HD 187123 are presented. Photometric precision of 0.0015 - 0.0023 magnitudes is achieved. No transits are observed at the epochs predicted from the radial velocity observation. If the planet orbiting HD 187123 at 0.0415 AU is an inflated Jupiter similar in radius to HD 209458b it would have been detected at the greater than 6(sigma), level if the orbital inclination is near 90 degrees and at the greater than 3(sigma), level if the orbital inclination is as small as 82.7 degrees.

  5. Propensity of lignin to associate: light scattering photometry study with native lignins.

    PubMed

    Contreras, Sofía; Gaspar, Armindo R; Guerra, Anderson; Lucia, Lucian A; Argyropoulos, Dimitris S

    2008-12-01

    Many studies of lignins in solution invoke association and aggregation phenomena to explain their solution behavior (e.g., reprecipitation onto pulp fibers, condensation, etc.). Following their colloidal (apparent) molecular weights in solution as a function of time allows us to explore observable dissociation phenomena. These measurements were carried out using multiple angle laser light scattering (MALLS) photometry in the static mode. The challenges and opportunities of measuring the specific refractive index increment (dn/dC) of lignin solutions and determining the kinetics of the dissociation process were thus investigated. Hardwood and softwood representative lignins were isolated, and method for their full dissolution in THF was further developed, which then lead to accurate dn/dC values being obtained as a function of time. When coupled to additional work using light scattering static measurements and Zimm plots for the same solutions, this effort offers insight into the aggregation and ensuing dissociative events that operate within the lignin macromolecules.

  6. Macular pigment density and distribution: comparison of fundus autofluorescence with minimum motion photometry.

    PubMed

    Robson, Anthony G; Moreland, Jack D; Pauleikhoff, Daniel; Morrissey, Tony; Holder, Graham E; Fitzke, Fred W; Bird, Alan C; van Kuijk, Frederik J G M

    2003-07-01

    Macular pigment (MP) distribution profiles were measured for 18 subjects using a Moreland anomaloscope modified for motion photometry. The total amount of MP within the central 7 degrees was estimated from the distribution profile by numerical integration. Fundus autofluorescence images were obtained for eight of these subjects using a scanning laser ophthalmoscope. Peak optical density of MP increased with the total amount present, but the correlation was weakened by inter-subject differences in MP distribution. The mean MP distribution derived from mean grey-scale profiles of fundus autofluorescence images correlated closely with that obtained psychophysically (r=0.96). Autofluorescence imaging provides a fast non-invasive method for assessing MP in vivo.

  7. Faint quasi-stellar-object candidates in selected areas 28 and 68 identified from multicolor photometry

    SciTech Connect

    Shields, J.C.; Koo, D.C.; Kron, R.C.; California Univ., Berkeley; Lick Observatory, Santa Cruz, CA; Yerkes Observatory, Williams Bay, WI )

    1989-04-01

    Forty-five QSO candidates over a total area of 0.53 square degree in two fields at high Galactic latitudes have been identified. These candidates reached B of about 21.5 for field Lynx.3 in SA 28 and B of about 22 for field SA68.2, and were selected from a subset of objects in catalogs generated from multicolor photometry (UBV) of deep Kitt Peak 4-m plates with limits of B of about 24. This subset consists of all objects which appeared stellar-like in size but which did not have the UBV colors of common Galactic stars. Besides several probable high-redshift QSOs, this study yields faint QSO counts consistent with those from other surveys, and thus provides further support to models that include mainly the luminosity evolution of QSOs. 29 refs.

  8. Confirmation and Photometry of Five Optical Nova Candidates in M81

    NASA Astrophysics Data System (ADS)

    Hornoch, K.; Fohring, D.; Karjalainen, R.

    2012-01-01

    We report confirmation of five nova candidates in M81 discovered on 2012 Jan. 9.102 UT (ATEL #3871). On Jan. 21.196 UT we obtained four 400-s narrow-band H-alpha CCD frames with the 2.5-m Isaac Newton Telescope + WFC at La Palma under ~1.5" seeing. The single frames were co-added and the co-added image was used for confirmation of the nova candidates and the photometry. The candidates (except PNV J09553792+6902498, which is visible at the limit) are well visible on the co-added image as well as nova PNV J09553266+6906072 (ATEL #3735, #3770, and #3871) and PNV J09553281+6902028 (ATEL #3867).

  9. Photometry of Pluto-Charon mutual events and Hirayama family asteroids

    NASA Technical Reports Server (NTRS)

    Binzel, Richard P.

    1991-01-01

    During 1985 to 1990, nature provided earth bound astronomers with a once-per-century opportunity to observe occultation and transit phenomena between Pluto and its satellite, Charon. Ground based observations of these events are now being used to derive physical parameters for the Pluto-Charon system to a precision that is unlikely to be improved upon until in situ spacecraft observations are obtained. This program supports analysis of photometry observations from McDonald Observatory, a critical location in the International Pluto Campaign network. Knowledge of the diameters, masses, densities, and compositions derived from these observations will augment the understanding of Pluto's origin and its context within the problem of solar system formation.

  10. Optical Photometry of the Double-lined Cataclysmic Variable Phoenix 1

    NASA Astrophysics Data System (ADS)

    Hoard, D. W.; Wachter, S.; Kim-Quijano, Jessica

    2001-04-01

    We have obtained 7 nights of time-resolved VI photometry of the double-lined cataclysmic variable Phoenix 1. We detect two candidate orbital periods, 0.1344 day and 0.2683 day. The former, which would correspond to a single modulation caused by viewing the irradiated face of the secondary star, is the less favored choice based on the folded light curves. The latter, which would correspond to a double modulation with unequal minima depths caused by ellipsoidal variation of the secondary star, is inconsistent with the observed late spectral type (M2-5) of the secondary star. However, we discuss some recent results from the literature that may make it possible to reconcile the longer orbital period and later spectral type. Some ambiguity remains as to which of these two periods is the true orbital period.

  11. Improvements to photometry. Part 1: Better estimation of derivatives in extinction and transformation equations

    NASA Technical Reports Server (NTRS)

    Young, Andrew T.

    1988-01-01

    Atmospheric extinction in wideband photometry is examined both analytically and through numerical simulations. If the derivatives that appear in the Stromgren-King theory are estimated carefully, it appears that wideband measurements can be transformed to outside the atmosphere with errors no greater than a millimagnitude. A numerical analysis approach is used to estimate derivatives of both the stellar and atmospheric extinction spectra, avoiding previous assumptions that the extinction follows a power law. However, it is essential to satify the requirements of the sampling theorem to keep aliasing errors small. Typically, this means that band separations cannot exceed half of the full width at half-peak response. Further work is needed to examine higher order effects, which may well be significant.

  12. Minor planets and related objects. IX - Photometry and polarimetry of /1685/ Toro.

    NASA Technical Reports Server (NTRS)

    Dunlap, J. L.; Gehrels, T.; Howes, M. L.

    1973-01-01

    UBV photometry, lightcurves, a polarization-phase relation, and rotational polarization curves of Toro were obtained, June-August 1972. The average colors are B-V = 0.87 and U-B = 0.47 mag, showing some reddening with phase. The geometric albedo of Toro in the B filter is 0.14 which corresponds to an effective mean radius of 2.2 km plus or minus 0.4 (p.e.). The rotational polarization curves indicate that the lightcurves are mostly due to shape, but some albedo variation over the surface is detected as well. The shape is elongated, and probably irregular, with a cross-sectional area ratio of about 3.2, the maximum effective radius is 2.8 km and the minimum, 1.6 km.

  13. Ultraviolet Imaging Telescope photometry of massive stars - The OB association NGC 206 in M31

    NASA Technical Reports Server (NTRS)

    Hill, Jesse K.; Pfarr, Barbara B.; Bohlin, Ralph C.; Isensee, Joan E.; O'Connell, Robert W.; Neff, Susan G.; Roberts, Morton S.; Smith, Andrew M.; Stecher, Theodore P.

    1992-01-01

    The Ultraviolet Imaging Telescope (UIT) obtained UV images of the giant M31 OB association NGC 206. Magnitudes in bands at 1520 and 2490 A were obtained for 30 massive stars, which demonstrate the effectiveness of UIT for photometry of moderately crowded hot stars to V about 21. The UV colors and magnitudes observed for stars in NGC 206 place them in the region of the color magnitude diagram occupied by evolutionary models for 30-60 solar mass stars, after correcting for extinction. The brighter stars are systematically redder than the fainter stars, indicating that they are supergiants of age about 4 Myr, while the fainter, bluer stars are nearer age zero. The relative numbers of probable supergiants measured by us and the number of probable main-sequence O stars measured from optical images are in agreement with the relative lifetimes. Calculated UIT colors are presented for a library of standard star spectra constructed from IUE and ground-based observations.

  14. BVRI CCD photometry of the metal-poor globular cluster NGC 4372

    SciTech Connect

    Alcaino, G.; Liller, W.; Alvarado, F.; Wenderoth, E. )

    1991-07-01

    BVRI CCD photometry is presented in two overlapping fields in the metal-poor globular cluster NGC 4372. The observations extend approximately 2 mag below the main-sequence turnoff to V about 21. By comparing the color-magnitude diagram (CMD) with those of clusters with similar metallicities, it is found that E(B-V) = 0.50 {plus minus} 0.03, and (m-M)v = 14.75 {plus minus} 0.06. Comparison with theoretical isochrones leads to a value E(B-V) = 0.53 {plus minus} 0.03. Comparison of the CMD with that of bright stars published by other authors yields a value for Delta V(TO-HB) = 3.3 {plus minus} 0.3. The weighted mean value of the age of the cluster, derived from the four colors, is 15 {plus minus} 4 Gyr (estimated external uncertainty). 17 refs.

  15. Uvby-beta photometry of visual double stars - Absolute magnitudes of intrinsically bright stars

    NASA Astrophysics Data System (ADS)

    Olsen, E. H.

    1982-05-01

    Individual absolute visual magnitudes M(v) are derived for intrinsically bright stars and evolved stars. The results are collected for 106 objects believed to be members of binary systems. uvby-beta photometry was empirically calibrated in terms of M(v) for main sequence stars and photoelectrically determined apparent magnitudes. The derived M(v) values are not significantly different from those stated in the Wilson catalogue (1976). Binary systems with main sequence primaries and secondary components off the main sequence were also investigated. Several systems in which at least one component may be in the pre-main sequence contraction stage are pointed out. A wide variety of comments and derived data are given individually for 136 double stars, including metallicities, distance moduli, and masses.

  16. VizieR Online Data Catalog: Velocities and photometry in Trumpler 20 (Donati+, 2014)

    NASA Astrophysics Data System (ADS)

    Donati, P.; Gaudin, Cantat; Bragaglia, A.; Friel, E.; Magrini, L.; Smiljanic, R.; Vallenari, A.; Tosi, M.; Sordo, R.; Tautvaisiene, G.; Blanco-Cuaresma, S.; Costado, M. T.; Geisler, D.; Klutsch, A.; Mowlavi, N.; Munoz, C.; San, Roman I.; Zaggia, S.; Gilmore, G.; Randich, S.; Bensby, T.; Flaccomio, E.; Koposov, S. E.; Korn, A. J.; Pancino, E.; Recio-Blanco, A.; Franciosini, E.; de Laverny, P.; Lewis, J.; Morbidelli, L.; Prisinzano, L.; Sacco, G.; Worley, C. C.; Hourihane, A.; Jofre, P.; Lardo, C.; Maiorca, E.

    2013-11-01

    We combined high quality photometry available in literature (Carraro et al., 2010AJ....140..954C, hereafter C10, and Platais et al., 2008, Cat. J/MNRAS/391/1482, hereafter P08) and the spectroscopic observations of the Gaia-ESO Survey to reevaluate the parameters of the open cluster Trumpler 20. 1370 star spectra, taken with UVES and GIRAFFE spectrograph at VLT/UT2, of both main sequence and red clump stars were exploited to estimate the radial velocity distribution of the cluster stars and select the most probable cluster members. 13 red clump stars observed with UVES were used to determine the cluster metallicity. With the improved information on metallicity and membership we used the photometric catalogues to estimate age, distance and average galactic reddening by means of the isochrone fitting method. We estimated the differential reddening on the cluster face and found to play a not negligible role on the CMD morphology. (2 data files).

  17. Finding year-long activity cycles in ground-based and space-borne photometry

    NASA Astrophysics Data System (ADS)

    Vida, Krisztián; Oláh, Katalin; Szabó, Róbert

    2015-08-01

    Using long­term ground­based photometry of fast­rotating M­-dwarfs (EY Dra, V405 And, GSC 3377­0296 and V374 Peg), all with rotational periods near 0.5 day, but with different internal structures, we found activity cycles in the form of long-­term brightness changes, on the time scales of about one year. Using the cycling stars as templates, we searched for similar, fast rotating (P < 1d), active, late­-type targets in the Kepler Input Catalogue. Analysing the light curves of these 39 stars, we found hints of 300­-900 day­-long cycles in 9 cases detecting small variations in the rotation periods caused by differential rotation and the changing spot emergence latitudes over the cycle (i.e., the butterfly diagram).

  18. Starspots and active regions on IN Com: UBVRI photometry and linear polarization

    NASA Astrophysics Data System (ADS)

    Alekseev, I. Yu.; Kozlova, O. V.

    2014-06-01

    The activity of the variable star IN Com is considered using the latest multicolor UBVRI photometry and linear polarimetric observations carried out during a decade. The photometric variability of the star is fully described using the zonal spottedness model developed at the Crimean Astrophysical Observatory (CrAO). Spotted regions cover up to 22% of the total stellar surface, with the difference in temperatures between the quiet photosphere and the spot umbra being 600 K. The spots are located at middle and low latitudes (40°-55°). The intrinsic broad-band linear polarization of IN Com and its rotational modulation in the U band due to local magnetic fields at the most spotted (active) stellar longitudes were detected for the first time.

  19. Radius constraints from high-speed photometry of 20 low-mass white dwarf binaries

    SciTech Connect

    Hermes, J. J.; Brown, Warren R.; Kilic, Mukremin; Gianninas, A.; Chote, Paul; Sullivan, D. J.; Winget, D. E.; Bell, Keaton J.; Falcon, R. E.; Winget, K. I.; Harrold, Samuel T.; Montgomery, M. H.; Mason, Paul A.

    2014-09-01

    We carry out high-speed photometry on 20 of the shortest-period, detached white dwarf binaries known and discover systems with eclipses, ellipsoidal variations (due to tidal deformations of the visible white dwarf), and Doppler beaming. All of the binaries contain low-mass white dwarfs with orbital periods of less than four hr. Our observations identify the first eight tidally distorted white dwarfs, four of which are reported for the first time here. We use these observations to place empirical constraints on the mass-radius relationship for extremely low-mass (≤0.30 M {sub ☉}) white dwarfs. We also detect Doppler beaming in several of these binaries, which confirms their high-amplitude radial-velocity variability. All of these systems are strong sources of gravitational radiation, and long-term monitoring of those that display ellipsoidal variations can be used to detect spin-up of the tidal bulge due to orbital decay.

  20. PHOTOMETRY OF VARIABLE STARS FROM DOME A, ANTARCTICA: RESULTS FROM THE 2010 OBSERVING SEASON

    SciTech Connect

    Wang, Lingzhi; Zhu, Zonghong; Macri, Lucas M.; Wang, Lifan; Ashley, Michael C. B.; Lawrence, Jon S.; Luong-Van, Daniel; Storey, John W. V.; Cui, Xiangqun; Feng, Long-Long; Gong, Xuefei; Liu, Qiang; Shang, Zhaohui; Yang, Huigen; Yang, Ji; Yuan, Xiangyan; Zhou, Xu; Zhu, Zhenxi; Pennypacker, Carl R.; York, Donald G.

    2013-12-01

    We present results from a season of observations with the Chinese Small Telescope ARray, obtained over 183 days of the 2010 Antarctic winter. We carried out high-cadence time-series aperture photometry of 9125 stars with i ∼< 15.3 mag located in a 23 deg{sup 2} region centered on the south celestial pole. We identified 188 variable stars, including 67 new objects relative to our 2008 observations, thanks to broader synoptic coverage, a deeper magnitude limit, and a larger field of view. We used the photometric data set to derive site statistics from Dome A. Based on two years of observations, we find that extinction due to clouds at this site is less than 0.1 and 0.4 mag during 45% and 75% of the dark time, respectively.

  1. Radiative transfer in the surfaces of atmosphereless bodies. III - Interpretation of lunar photometry

    NASA Technical Reports Server (NTRS)

    Lumme, K.; Irvine, W. M.

    1982-01-01

    Narrowband and UBV photoelectric phase curves of the entire lunar disk and surface photometry of some craters have been interpreted using a newly developed generalized radiative transfer theory for planetary regoliths. The data are well fitted by the theory, yielding information on both macroscopic and microscopic lunar properties. Derived values for the integrated disk geometric albedo are considerably higher than quoted previously, because of the present inclusion of an accurately determined opposition effect. The mean surface roughness, defined as the ratio of the height to the radius of a typical irregularity, is found to be 0.9 + or - 0.1, or somewhat less than the mean value of 1.2 obtained for the asteroids. From the phase curves, wavelength-dependent values of the single scattering albedo and the Henyey-Greenstein asymmetry factor for the average surface particle are derived.

  2. Multiwavelength photometry of thermochromic indicator solutions for temperature determination in multicuvettes.

    PubMed

    Schilling, K; Cumme, G A; Hoffmann-Blume, E; Hoppe, H; Horn, A

    1993-02-01

    If buffer/indicator systems are used as optical thermometers in multicuvettes, the temperature resolution is limited by errors of optical measurements produced mainly by variations of pathlength and blank transmittance of the wells. Theoretical and practical approaches show that, in multicuvettes, a between-well temperature resolution of < 0.05 degrees C can be achieved by multiwavelength photometry with use of the Tris/cresol red indicator system. Using up to three absorbances (A0, A1, A2) measured in the same well at different wavelengths for calculation of differences, quotients, and quotients of differences, we found the optimum temperature signal to be In(A1/A2), with equal-ranking absorbances changing with temperature in opposite directions. We have used the method successfully to measure the temperature profiles and temporal dynamics of temperatures at all positions in two types of multicuvettes under controlled conditions, or not controlled thermostatically.

  3. Imaging and photometry of comet C/1999 S4 (LINEAR) before perihelion and after breakup.

    PubMed

    Farnham, T L; Schleicher, D G; Woodney, L M; Birch, P V; Eberhardy, C A; Levy, L

    2001-05-18

    We analyzed photometric measurements and images of comet C/LINEAR before perihelion and after its breakup. Results from our photometry data include a lower limit of 0.44 kilometer for the radius of the nucleus before breakup, and a determination that it was depleted in carbon-chain molecules relative to most other comets. Our imaging and modeling results, which include a constraint on the rotational state of the nucleus, indicate that the disintegration likely started on 18 or 19 July 2000. The total mass detectable in the dust tail after the breakup was 3 x 10(8) kilograms, comparable to one of the fragments in the Hubble Space Telescope images; we therefore infer that most of the comet's original mass is hidden in remnants between 1 millimeter and 50 meters in diameter. PMID:11359005

  4. Photometric flats: an essential ingredient for photometry with wide-field imagers

    NASA Astrophysics Data System (ADS)

    Selman, Fernando J.

    2004-09-01

    We discuss the challenges to photometry introduced by internal redistribution of light in wide-field imaging cameras with focal-reducers. We have developed a simple least-squares procedure which can be used to determine the zero-point variations across the field. The method uses three orthogonally offseted images of a reasonably dense stellar field, plus an image containing at least three standard stars scattered across the field. The method, which does not require rotating the instrument, have been applied to correct data from the Wide Field Imager at La Silla. It has been shown to reduce a 12% center-to-edge gradient down to a ~2% rms variation accross the field. A new method which can be used with data taken during non-photometric nights is also presented.

  5. CCD photometry of the globular cluster NGC 5897 - Morphology of the color-magnitude diagram

    NASA Technical Reports Server (NTRS)

    Sarajedini, Ata

    1992-01-01

    The paper presents CCD photometry in the B and V bands of the Galactic globular cluster NGC 5897. The color-magnitude diagram (CMD) obtained for this cluster is used to examine the properties of the cluster and to compare the NGC 5897 to the well-known globular cluster M3. It was found that the metallicity of the NGC 5897 is in the range of the metallicity of M3 and that the age of NGC 5897 is about 2 Gyr greater than that of M3. The CMD for NGC 5897 also reveals a significant population of blue straggler stars (BSS) more massive than the cluster subgiant branch stars. A pseudomain sequence is constructed for NGC 5897 and the previously studied (Sarajedini and Da Costa, 1991) global cluster 6101, which includes the BSS and extends to the faintest regions of the unevolved main sequence.

  6. Small-amplitude red variables in the AAVSO photoelectric photometry program: period analysis

    NASA Astrophysics Data System (ADS)

    Percy, John R.; Yu, Lawrence

    The AAVSO photoelectric photometry program was established about a decade ago by Janet A. Mattei and John R. Percy in order to obtain long-term, high-precision observations of variables which (at least on some time scales) show variations which are too small to be monitored effectively by visual techniques. As of 1992, the photoelectric archive contained over 7000 observations in total (Landis, Mattei, and Percy 1992, IBVS No, 3739). Most of the stars in the photoelectric program are red variables. With almost a decade of data on these stars, it is now possible to perform an effective period analysis. This we have done using a Fourier analysis program generously provided to the variable star community by Dr. E.P. Belserene. We report the results of the analysis here. Many of the stars show variability on two distinct time scales: tens of days (presumably due to pulsation) and hundreds of days (cause unknown).

  7. Local constraints on cosmic string loops from photometry and pulsar timing

    SciTech Connect

    Pshirkov, M. S.; Tuntsov, A. V.

    2010-04-15

    We constrain the cosmological density of cosmic string loops using two observational signatures--gravitational microlensing and the Kaiser-Stebbins effect. Photometry from RXTE and CoRoT space missions and pulsar timing from Parkes Pulsar Timing Array, Arecibo and Green Bank radio telescopes allow us to probe cosmic strings in a wide range of tensions G{mu}/c{sup 2}=10{sup -16} divide 10{sup -10}. We find that pulsar timing data provide the most stringent constraints on the abundance of light strings at the level {Omega}{sub s{approx}}10{sup -3}. Future observational facilities such as the Square Kilometer Array will allow one to improve these constraints by orders of magnitude.

  8. Infrared photometry of the 1982-4 eclipse of Epsilon Aurigae

    NASA Technical Reports Server (NTRS)

    Backman, D. E.

    1985-01-01

    The infrared photometry of epsilon Aur performed prior to and during the ingress phase of the recent eclipse allowed the first solid determination of the temperature of the secondary object. The eclipse depth was significantly less at lambda 5 micrometers than in the near-infrared. This is explained by a model of the secondary as an opaque and very cool object with a temperature of approx. 500 K. During eclipse, the secondary blocks approximately 45% of the near infrared radiation from the primary star. At the same time, the radiation from the secondary remains completely unobscured, resulting in a shallower light curve at longer wavelengths. This phenomenon is well known in the study of eclipsing binary stars; if the two stars have different colors, then the net color of the system changes during eclipse. In the case of epsilon Aur, the eclipsing object has a color deep in the infrared, so the effect is only noticeable there.

  9. Broad-Band Optical Photometry of the LMXB PSR J1023+0038

    NASA Astrophysics Data System (ADS)

    Gonzalez, Emmanuel; Mason, P. A.; Robinson, E. L.

    2013-01-01

    Optical observations of the low-mass X-ray binary PSR J1023+0038 are presented. CCD photometry was collected with 10s integrations using the Argos camera on the 2.1 m Otto Struve Telescope of McDonald Observatory. Data was obtained during seven nights in February 2011 and January 2012. The light curves are quite similar to those obtained in previous studies, allowing a systematic period study of new data combined with three epochs of published light curves, covering a span of 8 years. An unambiguous period of 0.1980962(4) days is derived. An O-C diagram of the residuals is constructed and does not clearly require a significant period change.

  10. VizieR Online Data Catalog: HST photometry of stars in HD 97950 (Pang+, 2016)

    NASA Astrophysics Data System (ADS)

    Pang, X.; Pasquali, A.; Grebel, E. K.

    2016-07-01

    The HD97950 cluster and its immediate surroundings in the giant HII region NGC3603 were observed with the Hubble Space Telescope (HST). The ultraviolet (UV) data were taken with the High Resolution Channel (HRC) of the Advanced Camera for Surveys (ACS) in 2005 (GO 10602, PI: Jesus Maiz Apellaniz) through the F220W, F250W, F330W, and F435W filters. The HRC is characterized by a spatial resolution of 0.03"/pixel and a field of view of 29''*25''. The optical observations were carried out with the Wide Field and Planetary Camera 2 (WFPC2) in two epochs: 1997 (GO 6763, PI: Laurent Drissen) and 2007 (GO 11193, PI: Wolfgang Brandner) through the F555W, F675W, and F814W filters. The Planetary Camera (PC) chip was centered on the cluster (0.045"/pixel, 40''*40'') for both programs. Pang et al. 2013 (cat. J/ApJ/764/73) reduced the two-epoch WFPC2 data and identified more than 400 member stars on the PC chip via relative proper motions. Of these member stars, 142 are in common between the HRC and PC images and thus have UV and optical photometry available (see Table1). Among the HD97950 cluster member stars determined from relative proper motions (Pang et al. 2013, cat. J/ApJ/764/73, Table2), there are five main-sequence (MS) stars located in the cluster with projected distances of r<0.7pc from the center, for which there are also spectral types available from Table3 of Melena et al. (2008AJ....135..878M). The photometry of these five MS stars is presented in Table2. The individual color excesses and extinctions of the member main sequence stars are listed in Table3. (3 data files).

  11. Wide-field photometry of the Galactic globular cluster M22

    NASA Astrophysics Data System (ADS)

    Monaco, L.; Pancino, E.; Ferraro, F. R.; Bellazzini, M.

    2004-04-01

    We present wide-field photometry of the Galactic globular cluster M22 in the B, V and I passbands for more than 186 000 stars. The study is complemented by the photometry in two narrow-band filters centred on Hα and the adjacent continuum, and by infrared J, H and K magnitudes derived from the Two-Micron All-Sky Survey for ~2000 stars. Profiting from this huge data base, we completely characterized the evolved stellar sequences of the cluster by determining a variety of photometric parameters, including new photometric estimates of the mean metallicity, reddening and distance to the cluster. In particular, from our multiwavelength analysis, we re-examined the long-standing metallicity spread problem in M22. According to our data set, we conclude that most of the observed width of the red giant branch must be due to differential reddening, which amounts to a maximum of ΔE(B-V) ~= 0.06, although the presence of a small metallicity spread cannot be completely ruled out. More specifically, the maximum metallicity spread allowed by our data is of the order of Δ[Fe/H]~= 0.1-0.2 dex, i.e. not much more than that allowed by the photometric errors. Finally, we identified most of the known variable stars and peculiar objects in our field of view. In particular, we have found additional evidence supporting previous optical identifications of the central star of the planetary nebula IRAS 18333-2357, which is associated with M22.

  12. Uvby-B Photometry of High Velocity Stars. Photometric Parallaxes and Preliminary Kinematic Results

    NASA Astrophysics Data System (ADS)

    Schuster, W. J.

    1990-11-01

    RESUMEN. Se han explorado dos metodos para la determinaci6n de paralajes fotometricos usando fotometrfa uv - . Estos metodos dependen de las relaciones estandar de Crawford (1975) y de Olsen (1984) y de colores y magnitudes sinteticas de VandenBerg y Bell (1985). Ambos metodos incluyen una correcci6n evolucionaria de forma f6c0. Se calculan las distancias para las 711 estrellas de alta velocidad y pobres en metales en el catalogo uvby-p de Schuster y Nissen (1988). Se comparan estas con las distancias de Sandage y Fouts (1987) y Laird, Carney y Latham (1988) para las estrellas en comtfin. Tambien son aplicables nuestros metodos a estrellas de paralaje. En general las comparaciones son satisfactorias y las sistematicas son despreciables o pequefias. Las distancias finales de nuestras 711 estrellas se aplican a un numero de problemas cinematicos. Se estudian algunos diagramas interesantes, tales como el diagrama de energia de Toomre y el diagrama V(rot) versus [Fe/H]. ABSTRACT Two methods for the determination of parallaxes using uvbyP photometry are being explored. These methods depend upon the standard relations of Crawford (1975) and of Olsen (1984) and upon synthetic colors and magnitudes of VandenBerg and Bell (1985). Both include an evolutionary correction of the form f6c0. Distances are calculated for the 711 high-velocity and metal-poor stars in the uvby-P catalogue of Schuster and Nissen (1988). These are compared to the distances of Sandage and Fouts (1987) and Laird, Carney, and Lathain (1988) for stars in common. Also our methods are applied to parallax stars. In general the comparisons are good with negligible or small systematic differences. The final distances of our 711 stars are applied to a number of kinematical problems. Several interesting diagrams are studied, sucl as Toomre energy diagram and the plot of V(rot) versus [Fe/H]. Key words: DISTANCES - PHOTOMETRY - STARS-POPULATION II

  13. How to measure metallicity from five-band photometry with supervised machine learning algorithms

    NASA Astrophysics Data System (ADS)

    Acquaviva, Viviana

    2016-02-01

    We demonstrate that it is possible to measure metallicity from the SDSS five-band photometry to better than 0.1 dex using supervised machine learning algorithms. Using spectroscopic estimates of metallicity as ground truth, we build, optimize and train several estimators to predict metallicity. We use the observed photometry, as well as derived quantities such as stellar mass and photometric redshift, as features, and we build two sample data sets at median redshifts of 0.103 and 0.218 and median r-band magnitude of 17.5 and 18.3, respectively. We find that ensemble methods, such as random forests of trees and extremely randomized trees and support vector machines all perform comparably well and can measure metallicity with a Root Mean Square Error (RMSE) of 0.081 and 0.090 for the two data sets when all objects are included. The fraction of outliers (objects for which |Ztrue - Zpred| > 0.2 dex) is 2.2 and 3.9 per cent, respectively and the RMSE decreases to 0.068 and 0.069 if those objects are excluded. Because of the ability of these algorithms to capture complex relationships between data and target, our technique performs better than previously proposed methods that sought to fit metallicity using an analytic fitting formula, and has 3× more constraining power than SED fitting-based methods. Additionally, this method is extremely forgiving of contamination in the training set, and can be used with very satisfactory results for sample sizes of a few hundred objects. We distribute all the routines to reproduce our results and apply them to other data sets.

  14. Macular pigment density measured by autofluorescence spectrometry: comparison with reflectometry and heterochromatic flicker photometry.

    PubMed

    Delori, F C; Goger, D G; Hammond, B R; Snodderly, D M; Burns, S A

    2001-06-01

    We present a technique for estimating the density of the human macular pigment noninvasively that takes advantage of the autofluorescence of lipofuscin, which is normally present in the human retinal pigment epithelium. By measuring the intensity of fluorescence at 710 nm, where macular pigment has essentially zero absorption, and stimulating the fluorescence with two wavelengths, one well absorbed by macular pigment and the other minimally absorbed by macular pigment, we can make accurate single-pass measurements of the macular pigment density. We used the technique to measure macular pigment density in a group of 159 subjects with normal retinal status ranging in age between 15 and 80 years. Average macular pigment density was 0.48 +/- 0.16 density unit (D.U.) for a 2 degrees -diameter test field. We show that these estimates are highly correlated with reflectometric (mean: 0.23 +/- 0.07 D.U.) and psychophysical (mean: 0.37 +/- 0.26 D.U.; obtained by heterochromatic flicker photometry) estimates of macular pigment in the same subjects, despite the fact that systematic differences in the estimated density exist between techniques. Repeat measurements over both short- and long-time intervals indicate that the autofluorescence technique is reproducible: The mean absolute difference between estimates was less than 0.05 D.U., superior to the reproducibility obtained by reflectometry and flicker photometry. To understand the systematic differences between density estimates obtained from the different methods, we analyzed the underlying assumptions of each technique. Specifically, we looked at the effect of self-screening by visual pigment, the effect of changes in optical property of the deeper retinal layers, including the role of retinal pigmented epithelium melanin, and the role of secondary fluorophores and reflectors in the anterior layers of the retina.

  15. PHOTOMETRY AND PHOTOMETRIC REDSHIFT CATALOGS FOR THE LOCKMAN HOLE DEEP FIELD

    SciTech Connect

    Fotopoulou, S.; Salvato, M.; Hasinger, G.; Rovilos, E.; Brusa, M.; Lutz, D.; Burwitz, V.; Egami, E.; Henry, J. P.; Huang, J. H.; Rigopoulou, D.; Vaccari, M.

    2012-01-01

    We present broadband photometry and photometric redshifts for 187,611 sources located in {approx}0.5 deg{sup 2} in the Lockman Hole area. The catalog includes 388 X-ray-detected sources identified with the very deep XMM-Newton observations available for an area of 0.2 deg{sup 2}. The source detection was performed on the R{sub c}-, z'-, and B-band images and the available photometry is spanning from the far-ultraviolet to the mid-infrared, reaching in the best-case scenario 21 bands. Astrometry corrections and photometric cross-calibrations over the entire data set allowed the computation of accurate photometric redshifts. Special treatment is undertaken for the X-ray sources, the majority of which are active galactic nuclei (AGNs). For normal galaxies, comparing the photometric redshifts to the 253 available spectroscopic redshifts, we achieve an accuracy of {sigma}{sub {Delta}z/(1+z)} = 0.036, with 12.6% outliers. For the X-ray-detected sources, compared to 115 spectroscopic redshifts, the accuracy is {sigma}{sub {Delta}z/(1+z)} = 0.069, with 18.3% outliers, where the outliers are defined as sources with |z{sub phot} - z{sub spec}| > 0.15 Multiplication-Sign (1 + z{sub spec}). These results are a significant improvement over the previously available photometric redshifts for normal galaxies in the Lockman Hole, while it is the first time that photometric redshifts are computed and made public for AGNs for this field.

  16. BVRI main-sequence photometry of the globular cluster M4

    SciTech Connect

    Alcaino, G.; Liller, W.

    1984-09-01

    We present BV and RI photographic photometry of 1421 and 189 stars, respectively, in the intermediate metallicity globular cluster M4 (NGC 6121). This investigation includes the first results of RI main-sequence photometry of a globular cluster. The use of longer wavelengths and longer color baselines provides the potential of improved isochrone fittings and underscores the urgent need for calculations of RI synthetic isochrones to be compared with observations. The Pickering-Racine wedge was used with the ESO 3.6 m telescope, the Las Campanas 2.5 m du Pont telescope, and the CTIO 1 m Yale telescope to extend the photoelectric limit from Vroughly-equal16.1 to Vroughly-equal19.1. We have determined the position of the main-sequence turnoff to lie at V = 16.6 +- 0.2 (m.e.) and B-V = 0.80 +- 0.03 (m.e.). A comparison of our BV observations with the CCD data of Richer and Fahlman shows excellent agreement: the two fifucial main sequences agree at all points to within 0.025 mag and, on average, to 0.013 mag. For the cluster we derive a distance modulus (m-M)/sub V/ = 12.52 +- 0.2 and reddening E(B-V) = 0.44 +- 0.03, results which confirm that at a distance of 2 kpc, M4 is the closest globular clusters to the Sun. Using the isochrones of VandenBerg, we deduce an age 13 +- 2 Gyr. As noted in several other investigations, there is a striking deficiency of stars in certain parts of the color-magnitude diagram; in M4 we find a pronounced gap over approx.0.6 mag at the base of the subgiant branch.

  17. Millimagnitude Optical Photometry for the Transiting Planetary Candidate OGLE-TR-109

    NASA Astrophysics Data System (ADS)

    Fernández, José Miguel; Minniti, Dante; Pietrzynski, Grzegorz; Gieren, Wolfgang; Ruíz, María Teresa; Zoccali, Manuela; Udalski, Andrzej; Szeifert, Thomas

    2006-08-01

    We present precise V-band photometry for the low-amplitude transit candidate star OGLE-TR-109. This is an extreme case among the transiting candidates found by the OGLE group because of the early spectral type of the star (F0 V), the low transit amplitude (AI=0.008 mag), and the very short period (P=0.58909 days) of the orbiting companion. Using difference image photometry, we are able to achieve millimagnitude errors in the individual data points. One transit of this star is well defined in our light curve. This confirms the OGLE detection and rules out the possibility of a false positive. The measurement of this transit allows us to refine the transit amplitude (AV=0.006+/-0.001 mag) and the ephemerides for this interesting system, as well as the radius of the possible orbiting companion (RP=0.90RJ+/-0.09RJ) and the inclination of the orbit (i=77deg+/-5deg). Two other transits observed at lower S/N confirm the period of this system measured by OGLE. There is no evidence for a blend of the F-type main-sequence star with a redder eclipsing binary or for secondary transits in the present observations. The absence of ellipsoidal modulation in the light curve of the primary rules out a low-mass star companion or brown dwarf with M>14MJ+/-8MJ. The remaining possibilities for OGLE-TR-109 are a blend between the F-type star and a binary with a bluer primary star, or a new transiting extrasolar planet. Based on observations collected with the Very Large Telescope at Paranal Observatory [ESO Program 075.C-0427(A), J. M. F. and D. M. visiting observers].

  18. Spin period and attitude of satellites and space debris measured by using photometry

    NASA Astrophysics Data System (ADS)

    Shakun, Leonid; Koshkin, Nikolay; Korobeynikova, Elena; Strakhova, Svetlana; Melikyants, Seda; Ryabov, Andrey

    2016-07-01

    Photometry is an essential method for studying of the properties of the proper rotation of satellites and space debris. The observation method with high time resolution is used in the Odessa astronomical observatory for observations of artificial satellites. This method provides the measuring of the orbital motion and the proper rotation of satellites. Worth note, that the time resolution of the light curve and the accuracy of positioning in time of the details in the light curve are more important for the interpretation of the brightness variations than the precise measuring of the brightness. The rapid photometry allows not only registering of the flashes caused by mirror surfaces of structure satellite elements but also determining the indicatrix of the corresponding structure satellite element. This principal change of the photometric quality allows significant improving the interpretation of the satellites' light curves. We obtained a large amount of the photometric observations sequences of the satellites with time resolution 0.02 sec on the 50 cm telescope during last 11 years. We used this data for determination of the rotational parameters of several space objects. We present the method and results of the data analysis for the inactive satellites such as Envisat, Cbers-2B, Topex and other. Each of them changes its rotational parameters in its own way. For some satellites, the rotation period increases, for other it decreases. The rotation axis also change their orientation in space. The obtained information about rotation characteristics can be used for the precise numerical models of the satellite orbital motion and for the future Active Debris Removal missions.

  19. High speed phase-resolved 2-d UBV photometry of the Crab pulsar

    NASA Astrophysics Data System (ADS)

    Golden, A.; Shearer, A.; Redfern, R. M.; Beskin, G. M.; Neizvestny, S. I.; Neustroev, V. V.; Plokhotnichenko, V. L.; Cullum, M.

    2000-11-01

    We report a phase-resolved photometric and morphological analysis of UBV data of the Crab pulsar obtained with the 2-d TRIFFID high speed optical photometer mounted on the Russian 6m telescope. By being able to accurately isolate the pulsar from the nebular background at an unprecedented temporal resolution (1 μs), the various light curve components were accurately fluxed via phase-resolved photometry. Within the UBV range, our datasets are consistent with the existing trends reported elsewhere in the literature. In terms of flux and phase duration, both the peak Full Width Half Maxima and Half Width Half Maxima decrease as a function of photon energy. This is similarly the case for the flux associated with the bridge of emission. Power-law fits to the various light curve components are as follows; alpha = 0.07 +/- 0.19 (peak 1), alpha = -0.06 +/- 0.19 (peak 2) and alpha = -0.44 +/- 0.19 (bridge) - the uncertainty here being dominated by the integrated CCD photometry used to independently reference the TRIFFID data. Temporally, the main peaks are coincident to <= 10 μs although an accurate phase lag with respect to the radio main peak is compromised by radio timing uncertainties. The plateau on the Crab's main peak was definitively determined to be <= 55 μs in extent and may decrease as a function of photon energy. There is no evidence for non-stochastic activity over the light curves or within various phase regions, nor is there evidence of anything akin to the giant pulses noted in the radio. Finally, there is no evidence to support the existence of a reported 60 second modulation suggested to be as a consequence of free precession. Based on observations taken at SAO, Karachai-Cherkessia, Russia

  20. Vetting Kepler planet candidates in the sub-Jovian desert with multiband photometry

    NASA Astrophysics Data System (ADS)

    Colón, Knicole D.; Morehead, Robert C.; Ford, Eric B.

    2015-09-01

    We present new multiband transit photometry of three small (Rp ≲ 6 R⊕), short-period (P ≲ 6 d) Kepler planet candidates acquired with the Gran Telescopio Canarias. These observations supplement the results presented in Colón & Ford and Colón, Ford & Morehead, where we used multicolour transit photometry of five Kepler planet candidates to search for wavelength-dependent transit depths and either validate planet candidates or identify eclipsing binary false positives within our sample. In those previous studies, we provided evidence that three targets were false positives and two targets were planets. Here, we present observations that provide evidence supporting a planetary nature for Kepler Object of Interest (KOI) 439.01 and KOI 732.01, and we find that KOI 531.01, a 6 R⊕ planet candidate around an M dwarf, is likely a false positive. We also present a discussion of the purported `sub-Jovian desert' in the orbital period-planet radius plane, which cannot be easily explained by observational bias. Both KOI 439.01 and KOI 732.01 are likely planets located within the so-called desert and should be investigated with further follow-up observations. As only ˜30 of the ˜3600 currently active Kepler planet candidates are located within the sub-Jovian desert, it will be interesting to see if these candidates also survive the vetting process and fill in the gap in the period-radius plane. Confirming planets in this regime will be important for understanding planetary migration and evolution processes, and we urge additional follow-up observations of these planet candidates to confirm their nature.

  1. Mass accretion rates from multiband photometry in the Carina Nebula: the case of Trumpler 14

    NASA Astrophysics Data System (ADS)

    Beccari, G.; De Marchi, G.; Panagia, N.; Valenti, E.; Carraro, G.; Romaniello, M.; Zoccali, M.; Weidner, C.

    2015-01-01

    Context. We present a study of the mass accretion rates of pre-main sequence (PMS) stars in the cluster Trumpler 14 (Tr 14) in the Carina Nebula. Using optical multiband photometry we were able to identify 356 PMS stars showing Hα excess emission with equivalent width EW(Hα) > 20 Å. We interpret this observational feature as an indication that these objects are still actively accreting gas from their circumstellar medium. From a comparison of the HR diagram with PMS evolutionary models we derive ages and masses of the PMS stars. We find that most of the PMS objects are younger than 10 Myr with a median age of ~3 Myr. Surprisingly, we also find that ~20% of the mass accreting objects are older than 10 Myr. For each PMS star in Trumpler 14 we determine the mass accretion rate (Ṁacc) and discuss its dependence on mass and age. We finally combine the optical photometry with near-IR observations to build the spectral energy distribution (SED) for each PMS star in Tr 14. The analysis of the SEDs suggests the presence of transitional discs in which a large amount of gas is still present and sustains accretion onto the PMS object at ages older than 10 Myr. Our results, discussed in light of recent recent discoveries with Herschel of transitional discs containing a massive gas component around the relatively old PMS stars TW Hydrae, 49 Ceti, and HD 95086, support a new scenario n which old and evolved debris discs still host a significant amount of gas. Aims: Methods: Results:

  2. SWIFT/UVOT PHOTOMETRY OF THE PLANETARY NEBULA WeBo 1: UNMASKING A FAINT HOT COMPANION STAR

    SciTech Connect

    Siegel, Michael H.; Hoversten, Erik; Stark, Michele; Bond, Howard E.; Breeveld, Alice A. E-mail: hoversten@swift.psu.edu E-mail: bond@stsci.edu

    2012-08-15

    We present an analysis of over 150 ks of data on the planetary nebula WeBo 1 (PN G135.6+01.0) obtained with the Swift Ultraviolet Optical Telescope (UVOT). The central object of this nebula has previously been described as a late-type K giant barium star with a possible hot companion, most likely a young pre-white dwarf. UVOT photometry shows that while the optical photometry is consistent with a large cool object, the near-ultraviolet (NUV) photometry shows far more UV flux than could be produced by any late-type object. Using model stellar atmospheres and a comparison to UVOT photometry for the pre-white dwarf PG 1159-035, we find that the companion has a temperature of at least 40,000 K and a radius of, at most, 0.056 R{sub Sun }. While the temperature and radius are consistent with a hot compact stellar remnant, they are lower and larger, respectively, than expected for a typical young pre-white dwarf. This likely indicates a deficiency in the assumed UV extinction curve. We find that higher temperatures more consistent with expectations for a pre-white dwarf can be derived if the foreground dust has a strong 'blue bump' at 2175 A and a lower R{sub V}. Our results demonstrate the ability of Swift to both uncover and characterize hot hidden companion stars and to constrain the UV extinction properties of foreground dust based solely on UVOT photometry.

  3. SPATIALLY RESOLVED OBSERVATIONS OF THE BIPOLAR OPTICAL OUTFLOW FROM THE BROWN DWARF 2MASS J12073347-3932540

    SciTech Connect

    Whelan, E. T.; Ray, T. P.; Comeron, F.; Bacciotti, F.; Kavanagh, P. J.

    2012-12-20

    Studies of brown dwarf (BD) outflows provide information pertinent to questions on BD formation, as well as allowing outflow mechanisms to be investigated at the lowest masses. Here new observations of the bipolar outflow from the 24 M{sub JUP} BD 2MASS J12073347-3932540 are presented. The outflow was originally identified through the spectro-astrometric analysis of the [O I]{lambda}6300 emission line. Follow-up observations consisting of spectra and [S II], R-band and I-band images were obtained. The new spectra confirm the original results and are used to constrain the outflow position angle (P.A.) at {approx}65 Degree-Sign . The [O I]{lambda}6300 emission line region is spatially resolved and the outflow is detected in the [S II] images. The detection is firstly in the form of an elongation of the point-spread function (PSF) along the direction of the outflow P.A. Four faint knot-like features (labeled A-D) are also observed to the southwest of 2MASS J12073347-3932540 along the same P.A. suggested by the spectra and the elongation in the PSF. Interestingly, D, the feature furthest from the source, is bow shaped with the apex pointing away from 2MASS J12073347-3932540. A color-color analysis allows us to conclude that at least feature D is part of the outflow under investigation while A is likely a star or galaxy. Follow-up observations are needed to confirm the origin of B and C. This is a first for a BD, as BD optical outflows have to date only been detected using spectro-astrometry. This result also demonstrates for the first time that BD outflows can be collimated and episodic.

  4. A preliminary systematic search for red-clump stars in Galactic open clusters based on 2mass data

    NASA Astrophysics Data System (ADS)

    Zhang, Xi; Chen, Li; Li, Zhongmu

    2013-02-01

    Red-clump (RC) giants are intermediate-age, core-helium-burning stars. The RC can be used as a standard candle. In particular, the small variance of the RC's K-band intrinsic luminosity and its weak dependence on chemical composition and age make it an extremely useful distance indicator. In this paper, we use 2mass data to search for RC stars in a sample of 60 Galactic open clusters with known reddening, ages, and distances, and obtain an average value for the RC's absolute K s-band magnitude, M K s = -1.72 +/- 0.17 mag.

  5. The ability of intermediate-band Strömgren photometry to correctly identify dwarf, subgiant, and giant stars and provide stellar metallicities and surface gravities

    NASA Astrophysics Data System (ADS)

    Árnadóttir, A. S.; Feltzing, S.; Lundström, I.

    2010-10-01

    Context. Several large scale photometric and spectroscopic surveys are being undertaken to provide a more detailed picture of the Milky Way. Given the necessity of generalisation in the determination of, e.g., stellar parameters when tens and hundred of thousands of stars are considered it remains important to provide independent, detailed studies to verify the methods used in the surveys. Aims: Our first aim is to critically evaluate available calibrations for deriving [M/H] from Strömgren photometry. Secondly, we develop the standard sequences for dwarf stars to reflect their inherent metallicity dependence. Finally, we test how well metallicities derived from ugriz photometry reproduce metallicities derived from the well-tested system of Strömgren photometry. Methods: We evaluate available metallicity calibrations based on Strömgren uvby photometry for dwarf stars using a catalogue of stars with both uvby photometry and spectroscopically determined iron abundances ([Fe/H]). The catalogue was created for this project. Using this catalogue, we also evaluate available calibrations that determine log g. A larger catalogue, in which metallicity is determined directly from uvby photometry, is used to trace metallicity-dependent standard sequences for dwarf stars. We also perform comparisons, for both dwarf and giant stars, of metallicities derived from ugriz photometry with metallicities derived from Strömgren photometry. Results: We provide a homogenised catalogue of 451 dwarf stars with 0.3 < (b-y)0 < 1.0. All stars in the catalogue have uvby photometry and [Fe/H] determined from spectra with high resolution and high signal-to-noise ratios (S/N). Using this catalogue, we test how well various photometric metallicity calibrations reproduce the spectroscopically determined [Fe/H]. Using the preferred metallicity calibration for dwarf stars, we derive new standard sequences in the c1,0 versus (b-y)0 plane and in the c1,0 versus (v-y)0 plane for dwarf stars with 0

  6. The ASTRODEEP Frontier Fields catalogues. I. Multiwavelength photometry of Abell-2744 and MACS-J0416

    NASA Astrophysics Data System (ADS)

    Merlin, E.; Amorín, R.; Castellano, M.; Fontana, A.; Buitrago, F.; Dunlop, J. S.; Elbaz, D.; Boucaud, A.; Bourne, N.; Boutsia, K.; Brammer, G.; Bruce, V. A.; Capak, P.; Cappelluti, N.; Ciesla, L.; Comastri, A.; Cullen, F.; Derriere, S.; Faber, S. M.; Ferguson, H. C.; Giallongo, E.; Grazian, A.; Lotz, J.; Michałowski, M. J.; Paris, D.; Pentericci, L.; Pilo, S.; Santini, P.; Schreiber, C.; Shu, X.; Wang, T.

    2016-05-01

    Context. The Frontier Fields survey is a pioneering observational program aimed at collecting photometric data, both from space (Hubble Space Telescope and Spitzer Space Telescope) and from ground-based facilities (VLT Hawk-I), for six deep fields pointing at clusters of galaxies and six nearby deep parallel fields, in a wide range of passbands. The analysis of these data is a natural outcome of the Astrodeep project, an EU collaboration aimed at developing methods and tools for extragalactic photometry and creating valuable public photometric catalogues. Aims: We produce multiwavelength photometric catalogues (from B to 4.5 μm) for the first two of the Frontier Fields, Abell-2744 and MACS-J0416 (plus their parallel fields). Methods: To detect faint sources even in the central regions of the clusters, we develop a robust and repeatable procedure that uses the public codes Galapagos and Galfit to model and remove most of the light contribution from both the brightest cluster members, and the intra-cluster light. We perform the detection on the processed HST H160 image to obtain a pure H-selected sample, which is the primary catalogue that we publish. We also add a sample of sources which are undetected in the H160 image but appear on a stacked infrared image. Photometry on the other HST bands is obtained using SExtractor, again on processed images after the procedure for foreground light removal. Photometry on the Hawk-I and IRAC bands is obtained using our PSF-matching deconfusion code t-phot. A similar procedure, but without the need for the foreground light removal, is adopted for the Parallel fields. Results: The procedure of foreground light subtraction allows for the detection and the photometric measurements of ~2500 sources per field. We deliver and release complete photometric H-detected catalogues, with the addition of the complementary sample of infrared-detected sources. All objects have multiwavelength coverage including B to H HST bands, plus K

  7. VizieR Online Data Catalog: Optical and UV photometry of SN 2013dy (Zhai+, 2016)

    NASA Astrophysics Data System (ADS)

    Zhai, Q.; Zhang, J.-J.; Wang, X.-F.; Zhang, T.-M.; Liu, Z.-W.; Brown, P. J.; Huang, F.; Zhao, X.-L.; Chang, L.; Yi, W.-M.; Wang, C.-J.; Xin, Y.-X.; Wang, J.-G.; Lun, B.-L.; Zhang, X.-L.; Fan, Y.-F.; Zheng, X.-M.; Bai, J.-M.

    2016-08-01

    SN2013dy, an Type Ia supernova (SNIa), was discovered at roughly a magnitude of ~17.2mag on UT July 10.45 2013 (Universal Time) in an unfiltered image of the galaxy NGC7250 by the Lick observatory supernova search (Casper et al., 2013CBET.3588....1C). Our first observation of SN 2013dy is in spectroscopy on 2013 July 14 (Zhang & Wang 2013CBET.3394....1Z; 4.76days after the first light and published in Zheng et al. 2013ApJ...778L..15Z) with the Yunnan Faint Object Spectrograph and Camera (YFOSC) mounted at the Li-Jiang 2.4m Telescope (LJT) of Yunnan Observatories (YNAO), China. About two weeks later, we started to monitor this transient intensively at LJT in both ground-based UBVRI photometry and spectroscopy spanning from t~+0 to t~+180days. Ten local standard stars (see Table1 in the paper) in the field of SN2013dy are used to transform the instrumental magnitudes of SN2013dy to the standard Johnson UBV and Kron-Cousins RI system, as listed in Table2. Optical photometry data are also collected with the Tsinghua-NAOC 0.8m telescope (TNT) at Xing-Long Observation of National Astronomical Observatories (NAOC), China, from t~-2days to t~+150days. Additionally, three spectra were obtained at the Xing-Long 2.16 m telescope (hereafter XLT) with the Bei-Jing Faint Object Spectrograph and Camera (BFOSC). Furthermore, this target was also observed by the Ultra-Violet/Optical Telescope (UVOT) on board the Swift satellite. The Swift observatory began observing SN 2013dy on 2013 July 17.09, about 10days (t~-10days) before the B band maximum, and continued for approximately 26days (t~+15days). These photometric observations are performed in three UV filters (uvw2, uvm2, and uvw1) and three broadband optical filters (uu, bb, and vv). Table3 lists the final UVOT UV/optical magnitudes of SN2013dy. (2 data files).

  8. Messier 35 (NGC 2168) DANCe. I. Membership, proper motions, and multiwavelength photometry

    NASA Astrophysics Data System (ADS)

    Bouy, H.; Bertin, E.; Barrado, D.; Sarro, L. M.; Olivares, J.; Moraux, E.; Bouvier, J.; Cuillandre, J.-C.; Ribas, Á.; Beletsky, Y.

    2015-03-01

    Context. Messier 35 (NGC 2168) is an important young nearby cluster. Its age, richness and relative proximity make it an ideal target for stellar evolution studies. The Kepler K2 mission recently observed it and provided a high accuracy photometric time series of a large number of sources in this area of the sky. Identifying the cluster's members is therefore of high importance to optimize the interpretation and analysis of the Kepler K2 data. Aims: We aim to identify the cluster's members by deriving membership probabilities for the sources within 1° of the cluster's center, which is farther away than equivalent previous studies. Methods: We measure accurate proper motions and multiwavelength (optical and near-infrared) photometry using ground-based archival images of the cluster. We use these measurements to compute membership probabilities. The list of candidate members from the literature is used as a training set to identify the cluster's locus in a multidimensional space made of proper motions, luminosities, and colors. Results: The final catalog includes 338 892 sources with multiwavelength photometry. Approximately half (194 452) were detected at more than two epochs and we measured their proper motion and used it to derive membership probability. A total of 4349 candidate members with membership probabilities greater than 50% are found in this sample in the luminosity range between 10 mag and 22 mag. The slow proper motion of the cluster and the overlap of its sequence with the field and background sequences in almost all color-magnitude and color-color diagrams complicate the analysis and the contamination level is expected to be significant. Our study, nevertheless, provides a coherent and quantitative membership analysis of Messier 35 based on a large fraction of the best ground-based data sets obtained over the past 18 years. As such, it represents a valuable input for follow-up studies using, in particular, the Kepler K2 photometric time series

  9. Spectral properties of near-Earth and Mars-crossing asteroids using Sloan photometry

    NASA Astrophysics Data System (ADS)

    Carry, B.; Solano, E.; Eggl, S.; DeMeo, F. E.

    2016-04-01

    The nature and origin of the asteroids orbiting in near-Earth space, including those on a potentially hazardous trajectory, is of both scientific interest and practical importance. We aim here at determining the taxonomy of a large sample of near-Earth and Mars-crosser asteroids and analyze the distribution of these classes with orbit. We use this distribution to identify the source regions of near-Earth objects and to study the strength of planetary encounters to refresh asteroid surfaces. We measure the photometry of these asteroids over four filters at visible wavelengths on images taken by the Sloan Digital Sky Survey (SDSS). These colors are used to classify the asteroids into a taxonomy consistent with the widely used Bus-DeMeo taxonomy (DeMeo et al. [2009]. Icarus 202, 160-180) based on visible and near-infrared spectroscopy. We report here on the taxonomic classification of 206 near-Earth and 776 Mars-crosser asteroids determined from SDSS photometry, representing an increase of 40% and 663% of known taxonomy classifications in these populations. Using the source region mapper by Greenstreet et al. (Greenstreet, S., Ngo, H., Gladman, B. [2012]. Icarus, 217, 355-366), we compare for the first time the taxonomic distribution among near-Earth and main-belt asteroids of similar diameters. Both distributions agree at the few percent level for the inner part of the main belt and we confirm this region as a main source of near-Earth objects. The effect of planetary encounters on asteroid surfaces are also studied by developing a simple model of forces acting on a surface grain during planetary encounter, which provides the minimum distance at which a close approach should occur to trigger resurfacing events. By integrating numerically the orbit of the 519 S-type and 46 Q-type asteroids in our sample back in time for 500,000 years and monitoring their encounter distance with Venus, Earth, Mars, and Jupiter, we seek to understand the conditions for resurfacing

  10. AGES AND METALLICITIES OF CLUSTER GALAXIES IN A779 USING MODIFIED STROeMGREN PHOTOMETRY

    SciTech Connect

    Sreedhar, Yuvraj Harsha; Rakos, Karl D.; Hensler, Gerhard; Zeilinger, Werner W.; Odell, Andrew P.

    2012-03-01

    In the quest for the formation and evolution of galaxy clusters, Rakos and co-workers introduced a spectrophotometric method using modified Stroemgren photometry, but with the considerable debate toward the project's abilities, we re-introduce the system by testing for the repeatability of the modified Stroemgren colors and compare them with the Stroemgren colors, and check for the reproducibility of the ages and metallicities (using the Principle Component Analysis (PCA) technique and the GALEV models) for the six common galaxies in all three A779 data sets. As a result, a fair agreement between two filter systems was found to produce similar colors (with a precision of 0.09 mag in (uz - vz), 0.02 mag in (bz - yz), and 0.03 mag in (vz - vz)) and the generated ages and metallicities are also similar (with an uncertainty of 0.36 Gyr and 0.04 dex from PCA and 0.44 Gyr and 0.2 dex using the GALEV models). We infer that the technique is able to relieve the age-metallicity degeneracy by separating the age effects from the metallicity effects, but it is still unable to completely eliminate it. We further extend this paper to re-study the evolution of galaxies in the low mass, dynamically poor A779 cluster (as it was not elaborately analyzed by Rakos and co-workers in their previous work) by correlating the luminosity (mass), density, and radial distance with the estimated age, metallicity, and the star formation history. Our results distinctly show the bimodality of the young, low-mass, metal-poor population with a mean age of 6.7 Gyr ({+-} 0.5 Gyr) and the old, high-mass, metal-rich galaxies with a mean age of 9 Gyr ({+-} 0.5 Gyr). The method also observes the color evolution of the blue cluster galaxies to red (Butcher-Oemler phenomenon), and the downsizing phenomenon. Our analysis shows that modified Stroemgren photometry is very well suited for studying low- and intermediate-z clusters, as it is capable of observing deeper with better spatial resolution at

  11. MAPPING THE STELLAR STRUCTURE OF THE MILKY WAY THICK DISK AND HALO USING SEGUE PHOTOMETRY

    SciTech Connect

    De Jong, Jelte T. A.; Rix, Hans-Walter; Martin, Nicolas F.; Yanny, Brian; Dolphin, Andrew E.; Beers, Timothy C.

    2010-05-01

    We map the stellar structure of the Galactic thick disk and halo by applying color-magnitude diagram (CMD) fitting to photometric data from the Sloan Extension for Galactic Understanding and Exploration (SEGUE) survey. The SEGUE imaging scans allow, for the first time, a comprehensive analysis of Milky Way structure at both high and low latitudes using uniform Sloan Digital Sky Survey photometry. Incorporating photometry of all relevant stars simultaneously, CMD fitting bypasses the need to choose single tracer populations. Using old stellar populations of differing metallicities as templates, we obtain a sparse three-dimensional map of the stellar mass distribution at |Z|>1 kpc. Fitting a smooth Milky Way model comprising exponential thin and thick disks and an axisymmetric power-law halo allows us to constrain the structural parameters of the thick disk and halo. The thick-disk scale height and length are well constrained at 0.75 {+-} 0.07 kpc and 4.1 {+-} 0.4 kpc, respectively. We find a stellar halo flattening within {approx}25 kpc of c/a = 0.88 {+-} 0.03 and a power-law index of 2.75 {+-} 0.07 (for 7 kpc {approx_lt}R{sub GC} {approx_lt} 30 kpc). The model fits yield thick-disk and stellar halo densities at the solar location of {rho}{sub thick,sun} = 10{sup -2.3{+-}0.1} M{sub sun} pc{sup -3} and {rho}{sub halo,sun} = 10{sup -4.20{+-}0.05} M{sub sun} pc{sup -3}, averaging over any substructures. Our analysis provides the first clear in situ evidence for a radial metallicity gradient in the Milky Way's stellar halo: within R {approx_lt} 15 kpc the stellar halo has a mean metallicity of [Fe/H] {approx_equal} -1.6, which shifts to [Fe/H] {approx_equal} -2.2 at larger radii, in line with the two-component halo deduced by Carollo et al. from a local kinematic analysis. Subtraction of the best-fit smooth and symmetric model from the overall density maps reveals a wealth of substructures at all latitudes, some attributable to known streams and overdensities, and some

  12. Photometric calibration of NGS/POSS and ESO/SRC plates using the NOAO PDS measuring engine. II - Surface photometry

    NASA Technical Reports Server (NTRS)

    Cutri, Roc M.; Low, Frank J.; Guhathakurta, Puragra

    1993-01-01

    In this paper we present a method to calibrate surface photometry of faint sources measured from direct photographic plates, such as those of the NGS/POSS and ESO/SRC Sky Survey. This calibration procedure does not require scanning sensitometer spots on the plates, but instead uses measurements of the brightness profiles of many faint stars of known brightness to fit a linearized approximation to the characteristic curve. The approximation is valid for only low- to medium-density emulsions, so this technique is appropriate only for relatively faint emission. Comparison between measurements of representative extended sources on the NGS/POSS and CCD images indicates that surface photometry can be obtained from the Sky Survey plates accurate to 0.1-0.3 mag in the range mu(B) between 23 and 27 and mu(R) between 22 and 26 mag/sq arcsec.

  13. DEEP K{sub s} -NEAR-INFRARED SURFACE PHOTOMETRY OF 80 DWARF IRREGULAR GALAXIES IN THE LOCAL VOLUME

    SciTech Connect

    Fingerhut, Robin L.; McCall, Marshall L.; Argote, Mauricio; Cluver, Michelle E.; Nishiyama, Shogo; Rekola, Rami T. F.; Richer, Michael G.; Vaduvescu, Ovidiu; Woudt, Patrick A. E-mail: mccall@yorku.c E-mail: mcluver@ipac.caltech.ed E-mail: rareko@utu.f E-mail: ovidiuv@ing.iac.e

    2010-06-10

    We present deep near-infrared (K{sub s}) images and surface photometry for 80 dwarf irregular galaxies (dIs) within {approx}5 Mpc of the Milky Way. The galaxy images were obtained at five different facilities between 2004 and 2006. The image reductions and surface photometry have been performed using methods specifically designed for isolating faint galaxies from the high and varying near-infrared sky level. Fifty-four of the 80 dIs have surface brightness profiles which could be fit to a hyperbolic-secant (sech) function, while the remaining profiles could be fit to the sum of a sech and a Gaussian function. From these fits, we have measured central surface brightnesses, scale lengths, and integrated magnitudes. This survey is part of a larger study of the connection between large-scale structure and the global properties of dIs, the hypothesized building-blocks of more massive galaxies.

  14. The VVV-SkZ Pipeline: How to Get Automatic PSF-Fitting Photometry from the VVV Survey

    NASA Astrophysics Data System (ADS)

    Mauro, F.; Bidin, C. M.; Chené, A.; Geisler, D.; Alonso-García, J.; Borissova, J.; Carraro, G.

    2015-05-01

    We present the VVV-SkZ_pipeline, a DAOPHOT-based pipeline created to perform PSF-fitting photometry of the “VISTA Variables in the Vía Láctea” (VVV) ESO Public Survey data. The pipeline avoids repetitive interaction by the user, but still retains all the benefits, power, and accuracy of the DAOPHOT suite. The pipeline provides an astrometrized photometric catalog in the regime where other techniques fail, for example, producing reliable results up to 2 magnitudes brighter than the saturation limit. It also produces deeper and more accurate photometry. These achievements allow the VVV-SkZ_pipeline to produce data well anchored to the selected standard photometric system and allows the study of important stellar phenomena (i.e., tip of the red giant branch stars, red giant branches, horizontal branch morphology, RR Lyrae stars), that may be beyond the reach using other methods of photometric reduction.

  15. Two MASS photometry of open star clusters: King 13 and Berkeley 53

    NASA Astrophysics Data System (ADS)

    Haroon, A. A.; Ismail, H. A.; Alnagahy, F. Y.

    2014-08-01

    In the present work, we used the near-infrared JHKs photometric data from the 2-Micron All Sky Survey (2MASS) to determine the morphological and photometric parameters for two rarely studied open star clusters; King 13 and Berkeley 53. Luminosity function, mass function and dynamical relaxation time have been determined for the two clusters. We estimated the distances of 2.11±0.25 Kpc and 3.51±0.21 Kpc for King 13 and Berkeley 53 respectively, and both clusters have the same age 1.00±0.12 Gyr at solar metallicity; z=0.019.

  16. VizieR Online Data Catalog: VISTA-VHS (MOVIS) minor planets NIR photometry (Popescu+, 2016)

    NASA Astrophysics Data System (ADS)

    Popescu, M.; Licandro, J.; Morate, D.; de, Leon J.; Nedelcu, D. A.; Rebolo, R.; McMahon, R. G.; Gonzalez-Solares, E.; Irwin, M.

    2016-05-01

    The retrieved photometric data is provided as a set of catalogs called MOVIS. These catalogs are obtained using a pipeline that finds the objects based on their ephemeris, retrieves the data by interfacing with VHS tables, removes the wrong associations, and do a post processing of the data (averaging, data combine, and colors computation). The correctness and reliability of the pipeline was assessed by analyzing the error distributions and by comparing the results with the 2MASS dataset. The results are reported in three catalogs: the detections catalog (MOVIS-D), the magnitudes catalog (MOVIS-M), and the colors catalog (MOVIS-C). (3 data files).

  17. 1988-1991 photometry of the chromospherically active double-lined binary system HD 163621 = V835 Herculis

    NASA Technical Reports Server (NTRS)

    Hall, Douglas; Henry, Gregory W.

    1994-01-01

    Photometry in V and B with a 16-inch automatic telescope from 1988 to 1991 confirms the synchronous rotation suspected earlier and reveals variability up to 0.1M in the B bandpass at one epoch. Five spots formed with lifetimes ranging from 0.15 to 0.77 years. As with other rapid rotators, the differential rotation coefficient (k = 0.03) is significantly smaller than that of the Sun (k = 0.19).

  18. VizieR Online Data Catalog: High-speed photometry obs. of WD 1145+017 syst. (Gansicke+, 2016)

    NASA Astrophysics Data System (ADS)

    Gansicke, B. T.; Aungwerojwit, A.; Marsh, T. R.; Dhillon, V. S.; Sahman, D. I.; Veras, D.; Farihi, J.; Chote, P.; Ashley, R.; Arjyotha, S.; Rattanasoon, S.; Littlefair, S. P.; Pollacco, D.; Burleigh, M. R.

    2016-05-01

    We obtained high-speed photometry with the frame-transfer camera ULTRASPEC mounted on the 2.4m Thai National Telescope (TNT) on Doi Inthanon over eleven nights in between 2015, November 28, and December 22. Additional observations were obtained on 2015, December 17, 23-25, using the Warwick 1m (W1m) telescope at the Roque de Los Muchachos Observatory on La Palma. (1 data file).

  19. Photometry, Astrometry, and Young Discoveries of Ultracool Dwarfs in the Pan-STARRS1 3π Survey

    NASA Astrophysics Data System (ADS)

    Best, William M. J.; Magnier, Eugene A.; Liu, Michael C.

    2016-01-01

    The Pan-STARRS1 3π Survey (PS1) has observed three-quarters of the sky in five optical bands (grizy) over multiple epochs spanning four years, creating an unprecedented resource for discovering and characterizing ultracool dwarfs. We present an analysis of the PS1 photometry and astrometry of all known L and T dwarfs. We will also highlight some especially interesting and serendipitous discoveries of young ultracool dwarfs.

  20. VizieR Online Data Catalog: Wide-field photometry of the GC Palomar 5 (Ibata+, 2016)

    NASA Astrophysics Data System (ADS)

    Ibata, R. A.; Lewis, G. F.; Martin, N. F.

    2016-05-01

    The primary source of photometry for this project was obtained with the MegaCam instrument at the 3.6m Canada-France-Hawaii Telescope (CFHT) during the 2006-2008 spring observing seasons. We also secured photometric observations of the cluster and its stream using the Mosaic II imager on the Mayall 4m Telescope at Kitt Peak National Observatory (KPNO) on 2010 June 4-8. (2 data files).

  1. Photoelectric photometry era at the Astronomical Institute of the Slovak Academy of Sciences II. Software and reduction techniques

    NASA Astrophysics Data System (ADS)

    Vaňko, M.; Komžík, R.; Kollár, V.; Sekeráš, M.

    2014-10-01

    We present a continuation of Paper9 I describing the photoelectric photometry at the Astronomical Institute of the Slovak Academy of Sciences at Tatranská Lomnica. In this article we show the observation principles and the basic ideas and philosophy of the photometer control software — the code UNIV, written by R. Komžík and V. Kollár, and used for the data resulting from observations.

  2. Accurate PSF-matched photometry and photometric redshifts for the extreme deep field with the Chebyshev-Fourier functions

    NASA Astrophysics Data System (ADS)

    Jiménez-Teja, Y.; Benítez, N.; Molino, A.; Fernandes, C. A. C.

    2015-10-01

    Photometric redshifts, which have become the cornerstone of several of the largest astronomical surveys like PanStarrs, DES, J-PAS and LSST, require precise measurements of galaxy photometry in different bands using a consistent physical aperture. This is not trivial, due to the variation in the shape and width of the point spread function (PSF) introduced by wavelength differences, instrument positions and atmospheric conditions. Current methods to correct for this effect rely on a detailed knowledge of PSF characteristics as a function of the survey coordinates, which can be difficult due to the relative paucity of stars tracking the PSF behaviour. Here we show that it is possible to measure accurate, consistent multicolour photometry without knowing the shape of the PSF. The Chebyshev-Fourier functions (CHEFs) can fit the observed profile of each object and produce high signal-to-noise integrated flux measurements unaffected by the PSF. These total fluxes, which encompass all the galaxy populations, are much more useful for galaxy evolution studies than aperture photometry. We compare the total magnitudes and colours obtained using our software to traditional photometry with SEXTRACTOR, using real data from the COSMOS survey and the Hubble Ultra-Deep Field (HUDF). We also apply the CHEF technique to the recently published eXtreme Deep Field (XDF) and compare the results to those from COLORPRO on the HUDF. We produce a photometric catalogue with 35 732 sources (10 823 with signal-to-noise ratio ≥5), reaching a photometric redshift precision of 2 per cent due to the extraordinary depth and wavelength coverage of the eXtreme Deep Field images.

  3. PHASE-RESOLVED INFRARED SPECTROSCOPY AND PHOTOMETRY OF V1500 CYGNI, AND A SEARCH FOR SIMILAR OLD CLASSICAL NOVAE

    SciTech Connect

    Harrison, Thomas E.; Campbell, Randy D.; Lyke, James E. E-mail: jlyke@keck.hawaii.edu

    2013-08-01

    We present phase-resolved near-infrared photometry and spectroscopy of the classical nova (CN) V1500 Cyg to explore whether cyclotron emission is present in this system. While the spectroscopy do not indicate the presence of discrete cyclotron harmonic emission, the light curves suggest that a sizable fraction of its near-infrared fluxes are due to this component. The light curves of V1500 Cyg appear to remain dominated by emission from the heated face of the secondary star in this system. We have used infrared spectroscopy and photometry to search for other potential magnetic systems among old CNe. We have found that the infrared light curves of V1974 Cyg superficially resemble those of V1500 Cyg, suggesting a highly irradiated companion. The old novae V446 Her and QV Vul have light curves with large amplitude variations like those seen in polars, suggesting they might have magnetic primaries. We extract photometry for 79 old novae from the Two Micron All Sky Survey Point Source Catalog and use those data to derive the mean, un-reddened infrared colors of quiescent novae. We also extract WISE data for these objects and find that 45 of them were detected. Surprisingly, a number of these systems were detected in the WISE 22 {mu}m band. While two of those objects produced significant dust shells (V705 Cas and V445 Pup), the others did not. It appears that line emission from their ionized ejected shells is the most likely explanation for those detections.

  4. Improved Constraints on Type Ia Supernova Host Galaxy Properties using Multi-Wavelength Photometry and their Correlations with Supernova Properties

    SciTech Connect

    Gupta, Ravi R.; D'Andrea, Chris B.; Sako, Masao; Conroy, Charlie; Smith, Mathew; Bassett, Bruce; Frieman, Joshua A.; Garnavich, Peter M.; Jha, Saurabh W.; Kessler, Richard; Lampeitl, Hubert; /Portsmouth U., ICG /Fermilab

    2011-07-01

    We improve estimates of the stellar mass and mass-weighted average age of Type Ia supernova (SN Ia) host galaxies by combining UV and near-IR photometry with optical photometry in our analysis. Using 206 SNe Ia drawn from the full three-year Sloan Digital Sky Survey (SDSS-II) Supernova Survey (median redshift of z {approx} 0.2) and multi-wavelength host-galaxy photometry from SDSS, the Galaxy Evolution Explorer, and the United Kingdom Infrared Telescope Infrared Deep Sky Survey, we present evidence of a correlation (1.9{sigma} confidence level) between the residuals of SNe Ia about the best-fit Hubble relation and the mass-weighted average age of their host galaxies. The trend is such that older galaxies host SNe Ia that are brighter than average after standard light-curve corrections are made. We also confirm, at the 3.0{sigma} level, the trend seen by previous studies that more massive galaxies often host brighter SNe Ia after light-curve correction.

  5. VizieR Online Data Catalog: CCD photometry of Pal 1 (Borissova+ 1995)

    NASA Astrophysics Data System (ADS)

    Borissova, J.; Spassova, N.

    1997-06-01

    A CCD photometry of the halo cluster Palomar 1 is presented in the Thuan-Gunn photometric system. The principal sequences of the color-magnitude diagrams are delineated in different spectral bands. The color- magnitude diagrams of the cluster show a well defined red horizontal branch, a subgiant branch and a main-sequence down to about two magnitudes below the main sequence turnoff. The giant branch is absent and the brightest stars are the horizontal branch stars. The age of the cluster determined by comparison with the isochrones of Bell & VandenBerg (1987ApJS...63..335B) is consistent with an age in the interval 12-14Gyr. A distance modulus of (m-M)g0=15.38+/-0.15 magnitude and E(g-r)=0.16 has been derived. An estimate of the cluster structural parameters such as core radius and concentration parameter gives rc=1.5pc and c=1.46. A mass estimate of 1.1x103M⊙ and a mass-to-light ratio of 1.79 have been obtained using King's (1966AJ.....71...64K) method. The morphology of color-magnitude diagrams allows Pal 1 to be interpreted as probably a globular cluster rather than an old open one. For a description of the uvgr photometric system, see e.g. (1 data file).

  6. Fast IR photometry of V404 Cyg in outburst with CIRCE/GTC

    NASA Astrophysics Data System (ADS)

    Dallilar, Yigit; Eikenberry, Stephen S.; Garner, Alan; Stelter, Richard D.; Gandhi, Poshak; Hardy, Liam K.; Dhillon, Vik S.; Littlefair, Stuart; Fender, Rob; Mooley, Kunal P.

    2016-01-01

    We used the fast photometry mode of the Canarias InfraRed Camera Experiment (CIRCE) on the 10.4-meter Gran Telescopio Canarias to observe V404 Cyg, a stellar mass black hole binary, on June 25th for about one and a half hour during its 2015 outburst. CIRCE provided 10Hz sampling in the Ks-band (2.2 microns) In addition, we obtained simultaneous multi wavelength data from our collaborators: three GHz radio bands from the AMI telescope and two optical bands (g'-r') from ULTRACAM on the William Herschel 4.2-meter telescope. We extract spectral indices from the three radio bands and an optical-to-infrared color index from infrared and optical lightcurves. With a positive and increasing radio spectral index, we have identified an infrared outburst about 30 minutes with a clear self absorbed synchrotron ejection event. We further investigate the correlation between spectral indexes and multi wavelength flux measurements to understand evolution of ejection event. We also report on very fast IR flares and their correlation with optical events.

  7. STELLAR POPULATION PROPERTIES AND EVOLUTION ANALYSIS OF NGC 628 WITH PANCHROMATIC PHOTOMETRY

    SciTech Connect

    Zou Hu; Zhang Wei; Yang Yanbin; Zhou Xu; Jiang Zhaoji; Ma Jun; Wu Zhenyu; Wu Jianghua; Zhang Tianmeng; Fan Zhou

    2011-07-15

    Panchromatic spectral energy distribution from the ultraviolet, optical to infrared photometry of NGC 628, combined with evolutionary stellar population synthesis, is used to derive the spatially resolved age, metallicity, and reddening maps. These parameter distributions show that the bulge of this galaxy is a disk-like pseudobulge, which has a Sersic index close to the exponential law, rich gas, and a young circumnuclear ring structure. We also discover that the disk has two distinct regions with different radial age and metallicity gradients. The inner region is older and has a much steeper age gradient than the outer region of the disk. Both these two regions and the central young structure can be seen in the radial profile of the optical color. Based on the age and reddening distributions, we conclude that the pseudobulge and disk are likely to have grown via secular evolution, which is the redistribution of mass and energy through the angular momentum transport caused by the non-axisymmetric potential of the spirals. However, possible gas accretion events could affect the outer region of the disk due to abundant H I gas accumulating in the outer disk.

  8. Combined analysis of intracellular calcium with dual excitation fluorescence photometry and imaging

    NASA Astrophysics Data System (ADS)

    Uttenweiler, Dietmar; Wojciechowski, Reinhold; Makabe, Makoto; Veigel, Claudia; Fink, Rainer H.

    1995-10-01

    We have developed an integrated microscopy system combining fast dual-excitation fluorescence photometry and digital image analysis with high spatial resolution, based mainly on standard components. With the combination of these well-established techniques in one setup it is possible to monitor intracellular calcium with both sufficiently high temporal and high spatial resolution on the same preparation for many biological applications. Our system consists of a commercially available dual-excitation photometric system, an attached ICCD camera, and a frame grabber board. With this integrated setup one can easily switch between the fast photometric mode and the imaging mode. We used the system to record Fura-2 calcium images (340/380 nm ratios), which were correlated with the faster spot measurements and were analyzed by means of image processing. As an example for its application we reconstructed caffeine-induced calcium transient released from the sarcoplasmic reticulum of isolated and permeabilized skeletal muscle fiber preparations. Such a combined technique will also be important for cellular studies using other fluorescence indicators. Additionally, the described system has an external trigger facility that enables combination with other cell physiological methods, e.g., electrophysiological techniques.

  9. Gemini/GMOS photometry of intermediate-age star clusters in the Large Magellanic Cloud

    NASA Astrophysics Data System (ADS)

    Piatti, Andrés E.; Keller, Stefan C.; Mackey, A. Dougal; Da Costa, Gary S.

    2014-10-01

    We present Gemini South GMOS g, i photometry of 14 intermediate-age Large Magellanic Cloud (LMC) star clusters, namely: NGC 2155, 2161, 2162, 2173, 2203, 2209, 2213, 2231, 2249, Hodge 6, SL 244, 505, 674, and 769, as part of a continuing project to investigate the extended main-sequence turn-off (EMSTO) phenomenon. Extensive artificial star tests were made over the observed field of view. These tests reveal the observed behaviour of photometric errors with magnitude and crowding. The cluster stellar density radial profiles were traced from star counts over the extent of the observed field. We adopt cluster radii and build colour-magnitude diagrams (CMDs) with cluster features clearly identified. We used the cluster (g, g - i) CMDs to estimate ages from the matching of theoretical isochrones. The studied LMC clusters are confirmed to be intermediate-age clusters, which range in age 9.10 < log(t) < 9.60. NGC 2162 and NGC 2249 look like new EMSTO candidates, in addition to NGC 2209, on the basis of having dual red clumps.

  10. DIGITAL ACCESS TO A SKY CENTURY AT HARVARD: INITIAL PHOTOMETRY AND ASTROMETRY

    SciTech Connect

    Laycock, S.; Tang, S.; Grindlay, J.; Los, E.; Simcoe, R.; Mink, D.

    2010-10-15

    Digital Access to a Sky Century at Harvard (DASCH) is a project to digitize the collection of {approx}500,000 glass photographic plates held at Harvard College Observatory. The collection spans the time period from 1880 to 1985, during which time every point on the sky was been observed from 500 to 1000 times. In this paper, we describe the DASCH commissioning run, during which we developed the data-reduction pipeline, characterized the plates and fine-tuned the digitizer's performance and operation. This initial run consisted of 500 plates taken from a variety of different plate series, all containing the open cluster Praeseppe (M44). We report that accurate photometry at the 0.1 mag level is possible on the majority of plates, and demonstrate century-long light curves of various types of variable stars in and around M44. DASCH will generate a public online archive of the entire plate collection, including images, source catalogs, and light curves for nearly all astronomical objects brighter than about 17th magnitude.

  11. The stellar content of central dominant galaxies. I. CCD surface photometry

    SciTech Connect

    Mackie, G.; Visvanathan, N.; Carter, D. Royal Greenwich Observatory, Santa Cruz de la Palma )

    1990-08-01

    UBVRI CCD surface photometry and color gradients are presented for 10 central dominant galaxies (CDGs), comprising gE, D, and cD morphological types and covering the range of Bautz-Morgan cluster types. The mean magnitude of the color gradients to a radius of 20 kpc is in agreement with those found in recent CCD studies of bright ellipticals in Virgo. The size of the gradients are consistent with N-body model predictions in which these galaxies are formed or enhanced by merger events. Parameters such as ellipticity, position angle of the major axis, and deviation from ellipticity for eight single-nucleus CDGs are also given. All galaxies show large changes in ellipticity and position angle with radius, and can be considered similar to Kormendy's T3 class of galaxies, in which tidal effects on isophotal structure are very probable. Three out of eight single-nucleus CDGs, NGC 1399, NGC 6876 and IC 1860, show evidence of isochromal flattening inside 10 kpc. Five (three boxy, two disk) out of the eight single-nucleus CDGs display nonelliptical isophotes. 111 refs.

  12. Opponent and nonopponent contributions to the zebrafish electroretinogram using heterochromatic flicker photometry.

    PubMed

    Patterson, W F; McDowell, A L; Hughes, A; Bilotta, J

    2002-05-01

    While some lower vertebrates, such as zebrafish, do not appear to possess anatomically separate pathways of processing visual information (such as M-pathways and P-pathways), it is believed that separate processing of the visual stimulus (such as luminance and chromatic processing) is a basic requirement of vertebrate vision. In this study, spectral sensitivity functions were obtained from electroretinogram responses to heterochromatic flicker photometry stimuli at several flicker rates, including a low flicker rate (2 Hz), in an attempt to predominantly stimulate chromatic processes and a high flicker rate (16 Hz), in an attempt to predominantly stimulate luminance processes. In addition, chromatic adaptation was used to isolate and examine the temporal properties of the different cone-type contributions to the electroretinogram response. Spectral sensitivity functions based on responses to heterochromatic stimuli of a low flicker rate appeared to receive both opponent and nonopponent contributions; however, when the stimulus flicker rate was high, spectral sensitivity appeared to be a function of only nonopponent mechanisms. Also, the differences in cone contributions to the spectral sensitivity functions across the different flicker rates appear to be related to the temporal properties of the cone contributions to the electroretinogram response.

  13. Ozone monitoring using differential optical absorption spectroscopy (DOAS) and UV photometry instruments in Sohar, Oman.

    PubMed

    Nawahda, Amin

    2015-08-01

    Ground level ozone (O3) concentrations were measured across Sohar highway in Oman during a four-month period from September to December 2014 by using an open-path deferential optical absorption spectroscopy (DOAS) instrument. The monthly average concentrations of O3 varied from 19.6 to 29.4 ppb. The measurements of O3 are compared with the measurements of a non-open-path UV photometry analyzer (UVP). The percent difference (PD) concept and linear regression methods were used to compare the readings of the two instruments. The findings show high correlation coefficients between the measurements of the DOAS and UVP instruments. The DOAS measurements of O3 are found to be less than those measured by the UVP instrument; the correlation coefficients between absolute PD values and meteorological parameters and PM2.5 were very low indicating a minor effect; therefore, titrations of O3 by traffic emissions and difference in elevation could be the reason for the difference in the measurements of the two instruments.

  14. Stimulus edge effects in the measurement of macular pigment using heterochromatic flicker photometry.

    PubMed

    Smollon, William E; Wooten, Billy R; Hammond, Billy R

    2015-11-01

    Heterochromatic flicker photometry (HFP) is the most common technique of measuring macular pigment optical density (MPOD). Some data strongly suggest that HFP samples MPOD specifically at the edge of center-fixated circular stimuli. Other data have led to the conclusion that HFP samples over the entire area of the stimulus. To resolve this disparity, MPOD was measured using HFP and a series of solid discs of varying radii (0.25 to 2.0 deg) and with thin annuli corresponding to the edge of those discs. MPOD assessed with the two methods yielded excellent correspondence and linearity: Y=0.01+0.98X , r=0.96. A second set of experiments showed that if a disc stimulus is adjusted for no-flicker (the standard procedure) and simply reduced in size, no flicker is observed despite the higher level of MPOD in the smaller area. Taken together, these results confirm that MPOD is determined at the edge of the measuring stimulus when using stimulus sizes in the range that is in dispute (up to a radius of 0.75 deg). The basis for this edge effect can be explained by quantitative differences in the spatial-temporal properties of the visual field as a function of angular distance from the fixation point.

  15. The far-infrared behaviour of Herbig Ae/Be discs: Herschel PACS photometry

    NASA Astrophysics Data System (ADS)

    Pascual, N.; Montesinos, B.; Meeus, G.; Marshall, J. P.; Mendigutía, I.; Sandell, G.

    2016-02-01

    Herbig Ae/Be objects are pre-main sequence stars surrounded by gas- and dust-rich circumstellar discs. These objects are in the throes of star and planet formation, and their characterisation informs us of the processes and outcomes of planet formation processes around intermediate mass stars. Here we analyse the spectral energy distributions of disc host stars observed by the Herschel open time key programme "Gas in Protoplanetary Systems". We present Herschel/PACS far-infrared imaging observations of 22 Herbig Ae/Bes and 5 debris discs, combined with ancillary photometry spanning ultraviolet to sub-millimetre wavelengths. From these measurements we determine the diagnostics of disc evolution, along with the total excess, in three regimes spanning near-, mid-, and far-infrared wavelengths. Using appropriate statistical tests, these diagnostics are examined for correlations. We find that the far-infrared flux, where the disc becomes optically thin, is correlated with the millimetre flux, which provides a measure of the total dust mass. The ratio of far-infrared to sub-millimetre flux is found to be greater for targets with discs that are brighter at millimetre wavelengths and that have steeper sub-millimetre slopes. Furthermore, discs with flared geometry have, on average, larger excesses than flat geometry discs. Finally, we estimate the extents of these discs (or provide upper limits) from the observations. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.

  16. Deep BV CCD Photometry of the Metal-Rich Globular Cluster M71

    NASA Astrophysics Data System (ADS)

    Yim, H.-S.; Chun, M.-S.; Byun, Y.-I.

    Deep BV photometry for about 15,000 stars in the globular cluster M71 has been obtained from the 2.2 m University Hawaii Telescope using 2k CCD. The frames cover a 7.5' times 7.5' region of the cluster center through 220'' (about 7 core radii). A complete color-magnitude diagram(CMD) from the upper red-giant branch to the lower main sequence(Vlimit ~22 approximately 5 mag below the main-sequence turnoff) has been constructed. From the fitting of the CMD fiducial sequence to the New Yale Isochrone and the similar metallicity globular cluster 47 Tuc, we estimated the absolute and relative ages of this ``disk population'' globluar cluster. A luminosity function to Mv ~8.3 for the cluster main-sequence has been derived. Applying several theoretical mass-luminosity relations, we derived mass function of M71. We discuss the implications of this on recent HST results about low mass main-sequence stars' lumisoty function and on dynamical evolution of the globular cluster.

  17. Investigating the dusty torus of Seyfert galaxies using SOFIA/FORCAST photometry

    NASA Astrophysics Data System (ADS)

    Fuller, L.; Lopez-Rodriguez, E.; Packham, C.; Ramos-Almeida, C.; Alonso-Herrero, A.; Levenson, N. A.; Radomski, J.; Ichikawa, K.; García-Bernete, I.; González-Martín, O.; Díaz-Santos, T.; Martínez-Paredes, M.

    2016-11-01

    We present 31.5 μm imaging photometry of 11 nearby Seyfert galaxies observed from the Stratospheric Observatory For Infrared Astronomy (SOFIA) using the Faint Object infraRed CAmera for the SOFIA Telescope (FORCAST). We tentatively detect extended 31 μm emission for the first time in our sample. In combination with this new data set, subarcsecond resolution 1-18 μm imaging and 7.5-13 μm spectroscopic observations were used to compute the nuclear spectral energy distribution (SED) of each galaxy. We found that the turnover of the torus emission does not occur at wavelengths ≤31.5 μm, which we interpret as a lower-limit for the wavelength of peak emission. We used CLUMPY torus models to fit the nuclear infrared (IR) SED and infer trends in the physical parameters of the AGN torus for the galaxies in the sample. Including the 31.5 μm nuclear flux in the SED (1) reduces the number of clumpy torus models compatible with the data, and (2) modifies the model output for the outer radial extent of the torus for 10 of the 11 objects. Specifically, six (60 per cent) objects show a decrease in radial extent while four (40 per cent) show an increase. We find torus outer radii ranging from <1 to 8.4 pc.

  18. Photometry of Pluto-Charon mutual events and Hirayama family asteroids

    NASA Technical Reports Server (NTRS)

    Binzel, Richard P.

    1988-01-01

    Once every 124 years, nature provides earth-bound astronomers with the opportunity to observe occultation and transit phenomena between Pluto and its satellite, Charon. Ground-based observations of these events will allow precise physical parameters for the Pluto-Charon system to be derived which are unlikely to be improved upon until in situ spacecraft observations are obtained. The proposed program will continue to support photometry observations from McDonald Observatory, a critical location in an international Pluto Campaign network. Knowledge of the diameters, masses, densities, and compositions derived from these observations will augment our understanding of Pluto's origin and its context within the problem of solar system formation. A second task will continue to research the evolutionary processes which have occurred in the asteroid belt by measuring the physical properties of specific Hirayama family members. Photoelectric lightcurve observations of Koronis and Themis family members will be used to investigate the individual catastrophic collision events which formed each family. By comparing these properties with results of laboratory and numerical experiments, the outcomes of catastrophic disruptions and collisional evolution may be more precisely determined.

  19. SECONDARY ECLIPSE PHOTOMETRY OF THE EXOPLANET WASP-5b WITH WARM SPITZER

    SciTech Connect

    Baskin, Nathaniel J.; Knutson, Heather A.; Desert, Jean-Michel; Burrows, Adam; Fortney, Jonathan J.; Laughlin, Gregory; Lewis, Nikole K.; Agol, Eric; Charbonneau, David; Cowan, Nicolas B.; Deming, Drake; Langton, Jonathan; Showman, Adam P.

    2013-08-20

    We present secondary eclipse photometry of the extrasolar planet WASP-5b taken in the 3.6 and 4.5 {mu}m bands with the Spitzer Space Telescope's Infrared Array Camera as part of the extended warm mission. By estimating the depth of the secondary eclipse in these two bands we can place constraints on the planet's atmospheric pressure-temperature profile and chemistry. We measure secondary eclipse depths of 0.197% {+-} 0.028% and 0.237% {+-} 0.024% in the 3.6 {mu}m and 4.5 {mu}m bands, respectively. For the case of a solar-composition atmosphere and chemistry in local thermal equilibrium, our observations are best matched by models showing a hot dayside and, depending on our choice of model, a weak thermal inversion or no inversion at all. We measure a mean offset from the predicted center of eclipse of 3.7 {+-} 1.8 minutes, corresponding to ecos {omega} = 0.0025 {+-} 0.0012 and consistent with a circular orbit. We conclude that the planet's orbit is unlikely to have been perturbed by interactions with another body in the system as claimed by Fukui et al.

  20. VizieR Online Data Catalog: Photometry and spectroscopy of stars in Cz 30 (Hayes+, 2015)

    NASA Astrophysics Data System (ADS)

    Hayes, C. R.; Friel, E. D.; Slack, T. J.; Boberg, O. M.

    2016-06-01

    Cz 30 was observed using the Wisconsin-Indiana-Yale-NOAO (WIYN) 0.9m telescope with the S2KB imager, a 2048*2048 pixel CCD, with a pixel scale of 0.6"/pixel providing a total field of view of 20.5'*20.5'. Observations were taken on 2012 February 17 in B, V, and I filters with a typical seeing of about 1.5" and the CCD centered near the cluster center. We present our set of photometry in Table3. Cz 30 was also observed with the Hydra multi-object fiber positioner and Bench Spectrograph on the Wisconsin-Indiana-Yale-NOAO (WIYN) 3.5m telescope. The cluster was observed on 2014 January 18 and 19 and February 14 (UT) in the echelle mode, giving a dispersion of 0.16Å/pixel and covering the range of ~6060-6380Å. Table4 gives the results of velocity determinations for stars in Cz 30. Table5 gives lines used along with the measured equivalent widths. We obtained [Fe/H] estimates for 10 stars, whose final atmospheric parameters and abundances are given in Table6. (4 data files).