Observation of Planetary Motion Using a Digital Camera

ERIC Educational Resources Information Center

Meyn, Jan-Peter

2008-01-01

A digital SLR camera with a standard lens (50 mm focal length, f/1.4) on a fixed tripod is used to obtain photographs of the sky which contain stars up to 8[superscript m] apparent magnitude. The angle of view is large enough to ensure visual identification of the photograph with a large sky region in a stellar map. The resolution is sufficient to…

Digital Access to a Sky Century at Harvard: Initial Photometry and Astrometry

NASA Astrophysics Data System (ADS)

Laycock, S.; Tang, S.; Grindlay, J.; Los, E.; Simcoe, R.; Mink, D.

2010-10-01

Digital Access to a Sky Century at Harvard (DASCH) is a project to digitize the collection of ~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.

Infrared Sky Imager (IRSI) Instrument Handbook

DOE Office of Scientific and Technical Information (OSTI.GOV)

Morris, Victor R.

2016-04-01

The Infrared Sky Imager (IRSI) deployed at the Atmospheric Radiation Measurement (ARM) Climate Research Facility is a Solmirus Corp. All Sky Infrared Visible Analyzer. The IRSI is an automatic, continuously operating, digital imaging and software system designed to capture hemispheric sky images and provide time series retrievals of fractional sky cover during both the day and night. The instrument provides diurnal, radiometrically calibrated sky imagery in the mid-infrared atmospheric window and imagery in the visible wavelengths for cloud retrievals during daylight hours. The software automatically identifies cloudy and clear regions at user-defined intervals and calculates fractional sky cover, providing amore » real-time display of sky conditions.« less

Extraction of memory colors for preferred color correction in digital TVs

NASA Astrophysics Data System (ADS)

Ryu, Byong Tae; Yeom, Jee Young; Kim, Choon-Woo; Ahn, Ji-Young; Kang, Dong-Woo; Shin, Hyun-Ho

2009-01-01

Subjective image quality is one of the most important performance indicators for digital TVs. In order to improve subjective image quality, preferred color correction is often employed. More specifically, areas of memory colors such as skin, grass, and sky are modified to generate pleasing impression to viewers. Before applying the preferred color correction, tendency of preference for memory colors should be identified. It is often accomplished by off-line human visual tests. Areas containing the memory colors should be extracted then color correction is applied to the extracted areas. These processes should be performed on-line. This paper presents a new method for area extraction of three types of memory colors. Performance of the proposed method is evaluated by calculating the correct and false detection ratios. Experimental results indicate that proposed method outperform previous methods proposed for the memory color extraction.

A CATALOG OF BULGE+DISK DECOMPOSITIONS AND UPDATED PHOTOMETRY FOR 1.12 MILLION GALAXIES IN THE SLOAN DIGITAL SKY SURVEY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Simard, Luc; McConnachie, Alan W.; Trevor Mendel, J.

We perform two-dimensional, point-spread-function-convolved, bulge+disk decompositions in the g and r bandpasses on a sample of 1,123,718 galaxies from the Legacy area of the Sloan Digital Sky Survey Data Release Seven. Four different decomposition procedures are investigated which make improvements to sky background determinations and object deblending over the standard SDSS procedures that lead to more robust structural parameters and integrated galaxy magnitudes and colors, especially in crowded environments. We use a set of science-based quality assurance metrics, namely, the disk luminosity-size relation, the galaxy color-magnitude diagram, and the galaxy central (fiber) colors to show the robustness of our structuralmore » parameters. The best procedure utilizes simultaneous, two-bandpass decompositions. Bulge and disk photometric errors remain below 0.1 mag down to bulge and disk magnitudes of g {approx_equal} 19 and r {approx_equal} 18.5. We also use and compare three different galaxy fitting models: a pure Sersic model, an n{sub b} = 4 bulge + disk model, and a Sersic (free n{sub b}) bulge + disk model. The most appropriate model for a given galaxy is determined by the F-test probability. All three catalogs of measured structural parameters, rest-frame magnitudes, and colors are publicly released here. These catalogs should provide an extensive comparison set for a wide range of observational and theoretical studies of galaxies.« less

Maximizing the Performance of Automated Low Cost All-sky Cameras

NASA Technical Reports Server (NTRS)

Bettonvil, F.

2011-01-01

Thanks to the wide spread of digital camera technology in the consumer market, a steady increase in the number of active All-sky camera has be noticed European wide. In this paper I look into the details of such All-sky systems and try to optimize the performance in terms of accuracy of the astrometry, the velocity determination and photometry. Having autonomous operation in mind, suggestions are done for the optimal low cost All-sky camera.

Mining the SDSS SkyServer SQL queries log

NASA Astrophysics Data System (ADS)

Hirota, Vitor M.; Santos, Rafael; Raddick, Jordan; Thakar, Ani

2016-05-01

SkyServer, the Internet portal for the Sloan Digital Sky Survey (SDSS) astronomic catalog, provides a set of tools that allows data access for astronomers and scientific education. One of SkyServer data access interfaces allows users to enter ad-hoc SQL statements to query the catalog. SkyServer also presents some template queries that can be used as basis for more complex queries. This interface has logged over 330 million queries submitted since 2001. It is expected that analysis of this data can be used to investigate usage patterns, identify potential new classes of queries, find similar queries, etc. and to shed some light on how users interact with the Sloan Digital Sky Survey data and how scientists have adopted the new paradigm of e-Science, which could in turn lead to enhancements on the user interfaces and experience in general. In this paper we review some approaches to SQL query mining, apply the traditional techniques used in the literature and present lessons learned, namely, that the general text mining approach for feature extraction and clustering does not seem to be adequate for this type of data, and, most importantly, we find that this type of analysis can result in very different queries being clustered together.

New High Proper Motion Stars from the Digitized Sky Survey. II. Northern Stars with 0.5" yr-1 < μ < 2.0" yr-1 at High Galactic Latitudes

NASA Astrophysics Data System (ADS)

Lépine, Sébastien; Shara, Michael M.; Rich, R. Michael

2003-08-01

In a continuation of our systematic search for high proper motion stars in the Digitized Sky Survey, we have completed the analysis of northern sky fields at Galactic latitudes above 25°. With the help of our SUPERBLINK software, a powerful automated blink comparator developed by us, we have identified 1146 stars in the magnitude range 8

The SuperCOSMOS all-sky galaxy catalogue

NASA Astrophysics Data System (ADS)

Peacock, J. A.; Hambly, N. C.; Bilicki, M.; MacGillivray, H. T.; Miller, L.; Read, M. A.; Tritton, S. B.

2016-10-01

We describe the construction of an all-sky galaxy catalogue, using SuperCOSMOS scans of Schmidt photographic plates from the UK Schmidt Telescope and Second Palomar Observatory Sky Survey. The photographic photometry is calibrated using Sloan Digital Sky Survey data, with results that are linear to 2 per cent or better. All-sky photometric uniformity is achieved by matching plate overlaps and also by requiring homogeneity in optical-to-2MASS colours, yielding zero-points that are uniform to 0.03 mag or better. The typical AB depths achieved are BJ < 21, RF < 19.5 and IN < 18.5, with little difference between hemispheres. In practice, the IN plates are shallower than the BJ and RF plates, so for most purposes we advocate the use of a catalogue selected in these two latter bands. At high Galactic latitudes, this catalogue is approximately 90 per cent complete with 5 per cent stellar contamination; we quantify how the quality degrades towards the Galactic plane. At low latitudes, there are many spurious galaxy candidates resulting from stellar blends: these approximately match the surface density of true galaxies at |b| = 30°. Above this latitude, the catalogue limited in BJ and RF contains in total about 20 million galaxy candidates, of which 75 per cent are real. This contamination can be removed, and the sky coverage extended, by matching with additional data sets. This SuperCOSMOS catalogue has been matched with 2MASS and with WISE, yielding quasi-all-sky samples of respectively 1.5 million and 18.5 million galaxies, to median redshifts of 0.08 and 0.20. This legacy data set thus continues to offer a valuable resource for large-angle cosmological investigations.

A high performance cost-effective digital complex correlator for an X-band polarimetry survey.

PubMed

Bergano, Miguel; Rocha, Armando; Cupido, Luís; Barbosa, Domingos; Villela, Thyrso; Boas, José Vilas; Rocha, Graça; Smoot, George F

2016-01-01

The detailed knowledge of the Milky Way radio emission is important to characterize galactic foregrounds masking extragalactic and cosmological signals. The update of the global sky models describing radio emissions over a very large spectral band requires high sensitivity experiments capable of observing large sky areas with long integration times. Here, we present the design of a new 10 GHz (X-band) polarimeter digital back-end to map the polarization components of the galactic synchrotron radiation field of the Northern Hemisphere sky. The design follows the digital processing trends in radio astronomy and implements a large bandwidth (1 GHz) digital complex cross-correlator to extract the Stokes parameters of the incoming synchrotron radiation field. The hardware constraints cover the implemented VLSI hardware description language code and the preliminary results. The implementation is based on the simultaneous digitized acquisition of the Cartesian components of the two linear receiver polarization channels. The design strategy involves a double data rate acquisition of the ADC interleaved parallel bus, and field programmable gate array device programming at the register transfer mode. The digital core of the back-end is capable of processing 32 Gbps and is built around an Altera field programmable gate array clocked at 250 MHz, 1 GSps analog to digital converters and a clock generator. The control of the field programmable gate array internal signal delays and a convenient use of its phase locked loops provide the timing requirements to achieve the target bandwidths and sensitivity. This solution is convenient for radio astronomy experiments requiring large bandwidth, high functionality, high volume availability and low cost. Of particular interest, this correlator was developed for the Galactic Emission Mapping project and is suitable for large sky area polarization continuum surveys. The solutions may also be adapted to be used at signal processing subsystem levels for large projects like the square kilometer array testbeds.

Automatic Rotational Sky Quality Meter (R-SQM) Design and Software for Astronomical Observatories

NASA Astrophysics Data System (ADS)

Dogan, E.; Ozbaldan, E. E.; Shameoni, Niaei M.; Yesilyaprak, C.

2016-12-01

We have presented the new design of Sky Quality Meter (SQM) device that is an automatic rotational model of sky quality meter (R-SQM) carried out by DAG (Eastern Anatolia Observatory) Technical Team. R-SQM is required for determining the long-term changes of sky quality of an astronomical observatory and consists of four SQM devices mounted on a rotating shaft with different angles for scanning all sky. This system is controlled by a Raspberry Pi control card and a step motor with its driver and a special software.

SDSS-IV eBOSS emission-line galaxy pilot survey

DOE PAGES

Comparat, J.; Delubac, T.; Jouvel, S.; ...

2016-08-09

The Sloan Digital Sky Survey IV extended Baryonic Oscillation Spectroscopic Survey (SDSS-IV/eBOSS) will observe 195,000 emission-line galaxies (ELGs) to measure the Baryonic Acoustic Oscillation standard ruler (BAO) at redshift 0.9. To test different ELG selection algorithms, 9,000 spectra were observed with the SDSS spectrograph as a pilot survey based on data from several imaging surveys. First, using visual inspection and redshift quality flags, we show that the automated spectroscopic redshifts assigned by the pipeline meet the quality requirements for a reliable BAO measurement. We also show the correlations between sky emission, signal-to-noise ratio in the emission lines, and redshift error.more » Then we provide a detailed description of each target selection algorithm we tested and compare them with the requirements of the eBOSS experiment. As a result, we provide reliable redshift distributions for the different target selection schemes we tested. Lastly, we determine an target selection algorithms that is best suited to be applied on DECam photometry because they fulfill the eBOSS survey efficiency requirements.« less

SkICAT: A cataloging and analysis tool for wide field imaging surveys

NASA Technical Reports Server (NTRS)

Weir, N.; Fayyad, U. M.; Djorgovski, S. G.; Roden, J.

1992-01-01

We describe an integrated system, SkICAT (Sky Image Cataloging and Analysis Tool), for the automated reduction and analysis of the Palomar Observatory-ST ScI Digitized Sky Survey. The Survey will consist of the complete digitization of the photographic Second Palomar Observatory Sky Survey (POSS-II) in three bands, comprising nearly three Terabytes of pixel data. SkICAT applies a combination of existing packages, including FOCAS for basic image detection and measurement and SAS for database management, as well as custom software, to the task of managing this wealth of data. One of the most novel aspects of the system is its method of object classification. Using state-of-theart machine learning classification techniques (GID3* and O-BTree), we have developed a powerful method for automatically distinguishing point sources from non-point sources and artifacts, achieving comparably accurate discrimination a full magnitude fainter than in previous Schmidt plate surveys. The learning algorithms produce decision trees for classification by examining instances of objects classified by eye on both plate and higher quality CCD data. The same techniques will be applied to perform higher-level object classification (e.g., of galaxy morphology) in the near future. Another key feature of the system is the facility to integrate the catalogs from multiple plates (and portions thereof) to construct a single catalog of uniform calibration and quality down to the faintest limits of the survey. SkICAT also provides a variety of data analysis and exploration tools for the scientific utilization of the resulting catalogs. We include initial results of applying this system to measure the counts and distribution of galaxies in two bands down to Bj is approximately 21 mag over an approximate 70 square degree multi-plate field from POSS-II. SkICAT is constructed in a modular and general fashion and should be readily adaptable to other large-scale imaging surveys.

Day/night whole sky imagers for 24-h cloud and sky assessment: history and overview.

PubMed

Shields, Janet E; Karr, Monette E; Johnson, Richard W; Burden, Art R

2013-03-10

A family of fully automated digital whole sky imagers (WSIs) has been developed at the Marine Physical Laboratory over many years, for a variety of research and military applications. The most advanced of these, the day/night whole sky imagers (D/N WSIs), acquire digital imagery of the full sky down to the horizon under all conditions from full sunlight to starlight. Cloud algorithms process the imagery to automatically detect the locations of cloud for both day and night. The instruments can provide absolute radiance distribution over the full radiance range from starlight through daylight. The WSIs were fielded in 1984, followed by the D/N WSIs in 1992. These many years of experience and development have resulted in very capable instruments and algorithms that remain unique. This article discusses the history of the development of the D/N WSIs, system design, algorithms, and data products. The paper cites many reports with more detailed technical documentation. Further details of calibration, day and night algorithms, and cloud free line-of-sight results will be discussed in future articles.

Dark Skies are a Universal Resource: IYA Programs on Dark Skies Awareness

NASA Astrophysics Data System (ADS)

Walker, Constance E.; Bueter, C.; Pompea, S. M.; Berglund, K.; Mann, T.; Gay, P.; Crelin, B.; Collins, D.; Sparks, R.

2008-05-01

The loss of a dark night sky as a natural resource is a growing concern. It impacts not only astronomical research, but also health, ecology, safety, economics and energy conservation. Because of its relevance, "Dark Skies” is a theme of the US Node for the International Year of Astronomy (IYA). Its goal is to raise public awareness of the impact of artificial lighting on local environments by getting people involved in a variety of dark skies-related programs. To reach this goal, the ASP session will immerse participants in hands-on, minds-on activities, events and resources on dark skies awareness. These include a planetarium show on DVD, podcasting, social networking, a digital photography contest, The Great Switch Out, Earth Hour, National Dark Skies Week, a traveling exhibit, a 6-minute video tutorial, Dark Skies Teaching Sites, Astronomy Nights in the (National) Parks, Sidewalk Astronomy Nights, and unaided-eye and digital-meter star counting programs like GLOBE at Night. The ASP "Dark Skies” session is offered to provide IYA dark skies-related programs to a variety of attendees. Participants include professional or amateur astronomers, education and public outreach professionals, science center/museum/planetarium staff and educators who want to lead activities involving dark skies awareness in conjunction with IYA. During the session, each participant will be given a package of educational materials on the various dark skies programs. We will provide the "know-how” and the means for session attendees to become community leaders in promoting these dark skies programs as public events at their home institutions during IYA. Participants will be able to jump-start their education programs through the use of well-developed instructional materials and kits sent later if they commit to leading IYA dark skies activities. For more information about the IYA Dark Skies theme, visit http://astronomy2009.us/darkskies/.

The GLOBE at Night Campaign: Promoting Dark Skies Awareness Beyond IYA2009

NASA Astrophysics Data System (ADS)

Walker, Constance E.

2010-01-01

One of the most productive programs in the IYA2009 Dark Skies Awareness Cornerstone Project has been GLOBE at Night. The GLOBE at Night program has endeavored to promote social awareness of the dark sky by getting the general public to measure light pollution and submit results on-line. During IYA2009 alone, over 15,700 measurements from 70 countries were contributed during the 2-week campaign period. That amount is twice the number of measurements on average from previous years. The GLOBE at Night website explains clearly the simple-to-participate-in 5 step program and offers background information and interactive games on key concepts. The program has been expanded to include trainings of the general public, but especially educators in schools, museums and science centers, in unique ways. Education kits for Dark Skies Awareness have been distributed at these training workshops. The kit includes material for a light shielding demonstration, a digital Sky Quality Meter and Dark Skies Ranger Activities. The activities are on how unshielded light wastes energy, how light pollution affects wildlife and how you can participate in a citizen-science star-hunt like GLOBE at Night. In addition, projects are being developed for what to do with the data once it is taken. There were particularly spirited and creative GLOBE at Night campaigns around the world in 2009. One such "poster child” was carried out by 6500 students in northern Indiana. The students produced 3,391 GLOBE at Night measurements. To visualize the magnitudes of dark sky lost to light pollution, these students removed over 12,000 of the 35,000 stacked LEGO blocks that represented an ideal night sky across the school district. The presentation will provide an update with lessons learned, describe how people can become involved and take a look ahead at the program's sustainability. For further information, visit www.globe.gov/globeatnight.

Searching for white dwarfs candidates in Sloan Digital Sky Survey Data

NASA Astrophysics Data System (ADS)

Należyty, Mirosław; Majczyna, Agnieszka; Ciechanowska, Anna; Madej, Jerzy

2009-06-01

Large amount of observational spectroscopic data are recently available from different observational projects, like Sloan Digital Sky Survey. It's become more urgent to identify white dwarfs stars based on data itself i.e. without modelling white dwarf atmospheres. In particular, existing methods of white dwarfs identification presented in Kleinman et al. (2004) and in Eisenstein et al. (2006) did not allow to find all the white dwarfs in examined data. We intend to test various criteria of searching for white dwarf candidates, based on photometric and spectral features.

Additional Ultracool White Dwarfs Found In The Sloan Digital Sky Survey

DTIC Science & Technology

2008-05-20

Anderson,4 Patrick B . Hall,5 Jeffrey A. Munn,1 James Liebert,6 Gillian R. Knapp,7 D. Bizyaev,8 E. Malanushenko,8 V. Malanushenko,8 K . Pan,8 Donald P...ADDITIONAL ULTRACOOL WHITE DWARFS FOUND IN THE SLOAN DIGITAL SKY SURVEY Hugh C. Harris,1 Evalyn Gates,2 Geza Gyuk,2,3 Mark Subbarao ,2,3 Scott F...effective temperature of roughly 4000 K , the density of gas in the photosphere increases to a point where models of the atmosphere must include effects not

Dark Skies Ahead? Activities to Raise Awareness during the International Year of Astronomy

NASA Astrophysics Data System (ADS)

Walker, Constance E.; Isbell, D.; Pompea, S.

2007-12-01

"Dark Skies as a Universal Resource” is one of 7 themes targeted for the International Year of Astronomy in 2009. The theme's goal is to raise public awareness of the impact of artificial lighting on local environments and the ongoing loss of a dark night sky as a natural resource for much of the world's population. To reach this goal, activities are being developed which highlight dark skies preservation issues 1) through new technology (e.g., programs at planetaria, blogging, podcasting); 2) at events such as star parties and observatory open houses; 3) in arts, entertainment and storytelling (e.g., art competitions, documentaries, lectures, native American traditions); 4) through unaided-eye and digital-meter star count programs involving citizen-scientists; and 5) by relating them to public health, economic issues, ecological consequences, energy conservation, safety and security. A centerpiece of the Dark Skies theme is the unaided-eye and digital-meter versions of the GLOBE at Night program. The unaided-eye version directs citizen-scientists on how to observe and record the brightness of the night sky by matching its appearance toward the constellation of Orion with one of 7 stellar maps of different limiting magnitudes. For the "digital” version, low-cost meters are used by citizen-scientists to measure the integrated sky brightness. Data sets and maps of both versions are supplied on-line for further capstone activities. In the presentation, we will outline the activities being developed as well as plans for funding, implementation, marketing and the connections to the global cornerstone IYA project, "Dark Skies Awareness".

``Dark Skies are a Universal Resource'' Programs Planned for the International Year of Astronomy

NASA Astrophysics Data System (ADS)

Walker, C. E.; Berglund, K.; Bueter, C.; Crelin, B.; Duriscoe, D.; Moore, C.; Gauthier, A.; Gay, P. L.; Foster, T.; Heatherly, S. A.; Maddalena, R.; Mann, T.; Patten, K.; Pompea, S. M.; Sparks, R.; Schaaf, F.; Simmons, M.; Smith, C.; Smith, M.; Tafreshi, B.

2008-11-01

In an effort to help more people appreciate the ongoing loss of a dark night sky for much of the world's population and to raise public knowledge about diverse impacts of excess artificial lighting on local environments, the International Year of Astronomy's Dark Skies Working Group has established six ``Dark Skies'' programs and six ``Dark Skies'' resources. The Dark Skies programs include GLOBE at Night (with Earth Hour), Astronomy Nights in the [National] Parks, Dark Skies Discovery Sites, Quiet Skies, Good Neighbor Lighting, and a digital photography contest. Resources include the light education toolkit, the ``Let There Be Night'' DVD and planetarium program, the 6-minute video, online interactions like Second Life, podcasts, and traveling exhibits. The programs and resources are summarized here, as they were in a poster for the June 2008 ASP/AAS conference. For more information on these programs and resources, visit http://astronomy2009.us/darkskies/.

Imaging spectropolarimetry of cloudy skies

NASA Astrophysics Data System (ADS)

Pust, Nathan; Shaw, Joseph A.

2006-05-01

The polarization state of atmospheric radiance varies with cloudiness and cloud type. We have developed a dual-field-of-view imaging spectro-polarimeter for measuring atmospheric polarization in five spectral bands from 450 to 700 nm. This instrument improves the acquisition time of past full-sky digital camera designs to 400 ms using liquid crystal variable retarders (LCVRs). The system can be used to measure polarization with either fisheye or telephoto optics, allowing studies of all-sky and target polarization. We present and describe measurements of sky polarization with clear and variably cloudy sky conditions. In clear skies, we observe a slight upward trend of the degree of polarization with wavelength, in agreement with previous observations. Presence of clouds generally reduces both cloudy sky and surrounding clear sky degree of polarization. The polarization measured from a cloud often reflects only the Rayleigh scattering between the instrument and the cloud, but some of our recent data shows partially polarized cloud scattering.

Effects Of Light Pollution On The Movements Of Leptonycteris Curasoae Yerbabuenae In The Tucson Area

NASA Astrophysics Data System (ADS)

Barringer, Daniel; Walker, C.

2011-01-01

We used data from the GLOBE at Night project and telemetry tracking data of lesser long-nosed bats obtained by the Arizona Game and Fish Department to study the effects of light pollution on the flight paths of the bats between their day roosts and night foraging areas around the city of Tucson, AZ. With the visual limiting magnitude data from GLOBE at Night, we ran a compositional analysis with respect to the bats’ flight paths to determine whether the bats were selecting for or against flight through regions of particular night sky brightness levels. We found that the bats selected for the regions in which the limiting sky magnitudes fell between the ranges of 2.8-3.0 to 3.6-3.8 and 4.4-4.6 to 5.0-5.2, suggesting that the lesser long-nosed bat can tolerate a fair degree of urbanization. We also compared this result to contour maps created with digital Sky Quality Meter data. In this presentation, we present the results from our compositional analysis with respect to the habits of the lesser long-nosed bat. For more information, please visit www.globeatnight.org.

The Fifth Data Release of the Sloan Digital Sky Survey

DTIC Science & Technology

2007-10-01

Gilmore,10 Karl Glazebrook,8 Jim Gray,24 Eva K . Grebel,25 James E. Gunn,5 Ernst de Haas,5 Patrick B . Hall,26 Michael Harvanek,4 Suzanne L. Hawley,2...THE FIFTH DATA RELEASE OF THE SLOAN DIGITAL SKY SURVEY Jennifer K . Adelman-McCarthy,1 Marcel A. Agüeros,2 Sahar S. Allam,1,3 Kurt S. J. Anderson,4...Scott F. Anderson,2 James Annis,1 Neta A. Bahcall,5 Coryn A. L. Bailer-Jones,6 Ivan K . Baldry,7,8 J. C. Barentine,4 Timothy C. Beers,9 V. Belokurov,10

THE SLOAN DIGITAL SKY SURVEY STRIPE 82 IMAGING DATA: DEPTH-OPTIMIZED CO-ADDS OVER 300 deg{sup 2} IN FIVE FILTERS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jiang, Linhua; Fan, Xiaohui; McGreer, Ian D.

We present and release co-added images of the Sloan Digital Sky Survey (SDSS) Stripe 82. Stripe 82 covers an area of ∼300 deg{sup 2} on the celestial equator, and has been repeatedly scanned 70-90 times in the ugriz bands by the SDSS imaging survey. By making use of all available data in the SDSS archive, our co-added images are optimized for depth. Input single-epoch frames were properly processed and weighted based on seeing, sky transparency, and background noise before co-addition. The resultant products are co-added science images and their associated weight images that record relative weights at individual pixels. Themore » depths of the co-adds, measured as the 5σ detection limits of the aperture (3.''2 diameter) magnitudes for point sources, are roughly 23.9, 25.1, 24.6, 24.1, and 22.8 AB magnitudes in the five bands, respectively. They are 1.9-2.2 mag deeper than the best SDSS single-epoch data. The co-added images have good image quality, with an average point-spread function FWHM of ∼1'' in the r, i, and z bands. We also release object catalogs that were made with SExtractor. These co-added products have many potential uses for studies of galaxies, quasars, and Galactic structure. We further present and release near-IR J-band images that cover ∼90 deg{sup 2} of Stripe 82. These images were obtained using the NEWFIRM camera on the NOAO 4 m Mayall telescope, and have a depth of about 20.0-20.5 Vega magnitudes (also 5σ detection limits for point sources)« less

The Sloan Digital Sky Survey Stripe 82 Imaging Data: Depth-Optimized Co-adds Over 300 deg$^2$ in Five Filters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jiang, Linhua; Fan, Xiaohui; Bian, Fuyan

We present and release co-added images of the Sloan Digital Sky Survey (SDSS) Stripe 82. Stripe 82 covers an area of ~300 deg(2) on the celestial equator, and has been repeatedly scanned 70-90 times in the ugriz bands by the SDSS imaging survey. By making use of all available data in the SDSS archive, our co-added images are optimized for depth. Input single-epoch frames were properly processed and weighted based on seeing, sky transparency, and background noise before co-addition. The resultant products are co-added science images and their associated weight images that record relative weights at individual pixels. The depths of themore » co-adds, measured as the 5σ detection limits of the aperture (3.''2 diameter) magnitudes for point sources, are roughly 23.9, 25.1, 24.6, 24.1, and 22.8 AB magnitudes in the five bands, respectively. They are 1.9-2.2 mag deeper than the best SDSS single-epoch data. The co-added images have good image quality, with an average point-spread function FWHM of ~1'' in the r, i, and z bands. We also release object catalogs that were made with SExtractor. These co-added products have many potential uses for studies of galaxies, quasars, and Galactic structure. We further present and release near-IR J-band images that cover ~90 deg(2) of Stripe 82. These images were obtained using the NEWFIRM camera on the NOAO 4 m Mayall telescope, and have a depth of about 20.0-20.5 Vega magnitudes (also 5σ detection limits for point sources).« less

Morning twilight measured at Bandung and Jombang

NASA Astrophysics Data System (ADS)

Arumaningtyas, Eka Puspita; Raharto, Moedji; Herdiwijaya, Dhani

2012-06-01

Twilight divided into three categories namely, astronomical twilight, nautical twilight, and civil twilight. The three types of twilight can occur either in the evening or early morning. According to the U.S. Naval Observatory the three types distinguished by the depression (altitude of the sun below the horizon) for the evening or the morning twilight, -180, -120, and -60. Sky brightness measurements usually intended to determine the quality of the sky at some observation site or to determine the quality of the atmosphere by light pollution. Sky brightness data could be use for practical purposes such as to determine prayer times (Morning Prayer). This study describes the measurement of sky brightness using a light meter Sky Quality Meter. The measurements indicate the presence of different values and patterns in the twilight sky brightness. This variability highly determined by the weather conditions. Sky brightness shows a constant value shortly after the evening astronomical twilight and before morning astronomical twilight. Before the evening astronomical twilight and after morning astronomical twilight sky brightness showing continue changing.

Sloan Digital Sky Survey III photometric quasar clustering: Probing the initial conditions of the Universe

DOE PAGES

Ho, Shirley; Agarwal, Nishant; Myers, Adam D.; ...

2015-05-22

Here, the Sloan Digital Sky Survey has surveyed 14,555 square degrees of the sky, and delivered over a trillion pixels of imaging data. We present the large-scale clustering of 1.6 million quasars between z=0.5 and z=2.5 that have been classified from this imaging, representing the highest density of quasars ever studied for clustering measurements. This data set spans 0~ 11,00 square degrees and probes a volume of 80 h –3 Gpc 3. In principle, such a large volume and medium density of tracers should facilitate high-precision cosmological constraints. We measure the angular clustering of photometrically classified quasars using an optimalmore » quadratic estimator in four redshift slices with an accuracy of ~ 25% over a bin width of δ l ~ 10–15 on scales corresponding to matter-radiation equality and larger (0ℓ ~ 2–3).« less

The SkyMapper Transient Survey

NASA Astrophysics Data System (ADS)

Scalzo, R. A.; Yuan, F.; Childress, M. J.; Möller, A.; Schmidt, B. P.; Tucker, B. E.; Zhang, B. R.; Onken, C. A.; Wolf, C.; Astier, P.; Betoule, M.; Regnault, N.

2017-07-01

The SkyMapper 1.3 m telescope at Siding Spring Observatory has now begun regular operations. Alongside the Southern Sky Survey, a comprehensive digital survey of the entire southern sky, SkyMapper will carry out a search for supernovae and other transients. The search strategy, covering a total footprint area of 2 000 deg2 with a cadence of ⩽5 d, is optimised for discovery and follow-up of low-redshift type Ia supernovae to constrain cosmic expansion and peculiar velocities. We describe the search operations and infrastructure, including a parallelised software pipeline to discover variable objects in difference imaging; simulations of the performance of the survey over its lifetime; public access to discovered transients; and some first results from the Science Verification data.

Analysing baryon acoustic oscillations in sparse spectroscopic samples via cross-correlation with dense photometry

NASA Astrophysics Data System (ADS)

Patej, A.; Eisenstein, D. J.

2018-07-01

We develop a formalism for measuring the cosmological distance scale from baryon acoustic oscillations (BAO) using the cross-correlation of a sparse redshift survey with a denser photometric sample. This reduces the shot noise that would otherwise affect the autocorrelation of the sparse spectroscopic map. As a proof of principle, we make the first on-sky application of this method to a sparse sample defined as the z > 0.6 tail of the Sloan Digital Sky Survey's (SDSS) BOSS/CMASS sample of galaxies and a dense photometric sample from SDSS DR9. We find a 2.8σ preference for the BAO peak in the cross-correlation at an effective z = 0.64, from which we measure the angular diameter distance DM(z = 0.64) = (2418 ± 73 Mpc)(rs/rs, fid). Accordingly, we expect that using this method to combine sparse spectroscopy with the deep, high-quality imaging that is just now becoming available will enable higher precision BAO measurements than possible with the spectroscopy alone.

Analyzing Baryon Acoustic Oscillations in Sparse Spectroscopic Samples via Cross-Correlation with Dense Photometry

NASA Astrophysics Data System (ADS)

Patej, Anna; Eisenstein, Daniel J.

2018-04-01

We develop a formalism for measuring the cosmological distance scale from baryon acoustic oscillations (BAO) using the cross-correlation of a sparse redshift survey with a denser photometric sample. This reduces the shot noise that would otherwise affect the auto-correlation of the sparse spectroscopic map. As a proof of principle, we make the first on-sky application of this method to a sparse sample defined as the z > 0.6 tail of the Sloan Digital Sky Survey's (SDSS) BOSS/CMASS sample of galaxies and a dense photometric sample from SDSS DR9. We find a 2.8σ preference for the BAO peak in the cross-correlation at an effective z = 0.64, from which we measure the angular diameter distance DM(z = 0.64) = (2418 ± 73 Mpc)(rs/rs, fid). Accordingly, we expect that using this method to combine sparse spectroscopy with the deep, high quality imaging that is just now becoming available will enable higher precision BAO measurements than possible with the spectroscopy alone.

Transformations between the 2MASS, SDSS, and BV I photometric systems for late-type giants

NASA Astrophysics Data System (ADS)

Yaz, E.; Bilir, S.; Karaali, S.; Ak, S.; Coşkunoğlu, B.; Cabrera-Lavers, A.

2010-08-01

We present colour transformations from Two Micron All Sky Survey (2MASS) photometric system to Johnson-Cousins system and to Sloan Digital Sky Survey (SDSS) system for late-type giants and vice versa. The giant star sample was formed using surface gravity constraints ({2 < log g ≤ 3}) to Cayrel de Strobel et al.' s (2001) spectroscopic catalogue. 2MASS, SDSS and Johnson-Cousins photometric data was taken from \\cite{Cu03}, \\cite{Ofek08}, and \\cite{vanLeeuwen2007}, respectively. The final sample was refined applying the following steps: (1) the data were dereddened, (2) the sample stars selected are of the highest photometric quality. We give two-colour dependent transformations as a function of metallicity as well as independent of metallicity. The transformations provide absolute magnitudes and distance determinations which can be used in space density evaluations at relatively short distances where some or all of the SDSS magnitudes of late-type giants are saturated.

Light-pollution measurement with the Wide-field all-sky image analyzing monitoring system

NASA Astrophysics Data System (ADS)

Vítek, S.

2017-07-01

The purpose of this experiment was to measure light pollution in the capital of Czech Republic, Prague. As a measuring instrument is used calibrated consumer level digital single reflex camera with IR cut filter, therefore, the paper reports results of measuring and monitoring of the light pollution in the wavelength range of 390 - 700 nm, which most affects visual range astronomy. Combining frames of different exposure times made with a digital camera coupled with fish-eye lens allow to create high dynamic range images, contain meaningful values, so such a system can provide absolute values of the sky brightness.

Setting up the Sloan Digital Sky Survey Standard Star Network: The Starware

NASA Astrophysics Data System (ADS)

Smith, J. A.; Tucker, D. L.; Brinkmann, J.; Annis, J.; Briggs, J. W.; Doi, M.; Fukugita, M.; Gunn, J. E.; Hamabe, M.; Ichikawa, S.; Ichikawa, T.; Kent, S.; McKay, T. A.; McMillan, R.; Merrelli, A.; Newberg, H. J.; Richmond, M. W.; Watanabe, M.

1998-12-01

The Sloan Digital Sky Survey (SDSS) has achieved first light. Though still in the engineering shakedown year, the image quality of some of these early runs is useable for science results. Although similar to the Thuan-Gunn ugriz system, the SDSS u'g'r'i'z' system has wider effective bandwidths and covers almost the entire spectrum from the 3000 Angstroms/ to 11 000 Angstroms. This is a new photometric system; therefore, calibration of a network of primary standard stars is needed before the survey science results can be interpreted properly. Beginning in earnest in March 1998, we started the calibration observations to define the SDSS u'g'r'i'z' standard star system using the 40-inch Ritchey-Chretien telescope at the United States Naval Observatory's Flagstaff, Arizona Station. As described in the paper announcing the system [Fukugita et al. 1996], the zeropoints for each of the five filters will be set by the metal-poor F subdwarfs BD+17:4708, BD+26:2606 & BD+21:0607. In this paper, we describe the rest of the stars being considered as potential standards to define this new system, changes from the preliminary list presented last year [Smith et al. 1998], and give some early (NOT YET OFFICIAL) results. Descriptions of the reduction software (D.L. Tucker et al.) and the hardware used to obtain these observations (J. Brinkmann et al.) are described in companion posters.

A simplified model of all-sky artificial sky glow derived from VIIRS Day/Night band data

NASA Astrophysics Data System (ADS)

Duriscoe, Dan M.; Anderson, Sharolyn J.; Luginbuhl, Christian B.; Baugh, Kimberly E.

2018-07-01

We present a simplified method using geographic analysis tools to predict the average artificial luminance over the hemisphere of the night sky, expressed as a ratio to the natural condition. The VIIRS Day/Night Band upward radiance data from the Suomi NPP orbiting satellite was used for input to the model. The method is based upon a relation between sky glow brightness and the distance from the observer to the source of upward radiance. This relationship was developed using a Garstang radiative transfer model with Day/Night Band data as input, then refined and calibrated with ground-based all-sky V-band photometric data taken under cloudless and low atmospheric aerosol conditions. An excellent correlation was found between observed sky quality and the predicted values from the remotely sensed data. Thematic maps of large regions of the earth showing predicted artificial V-band sky brightness may be quickly generated with modest computing resources. We have found a fast and accurate method based on previous work to model all-sky quality. We provide limitations to this method. The proposed model meets requirements needed by decision makers and land managers of an easy to interpret and understand metric of sky quality.

ASERA: A spectrum eye recognition assistant for quasar spectra

NASA Astrophysics Data System (ADS)

Yuan, Hailong; Zhang, Haotong; Zhang, Yanxia; Lei, Yajuan; Dong, Yiqiao; Zhao, Yongheng

2013-11-01

Spectral type recognition is an important and fundamental step of large sky survey projects in the data reduction for further scientific research, like parameter measurement and statistic work. It tends out to be a huge job to manually inspect the low quality spectra produced from the massive spectroscopic survey, where the automatic pipeline may not provide confident type classification results. In order to improve the efficiency and effectiveness of spectral classification, we develop a semi-automated toolkit named ASERA, ASpectrum Eye Recognition Assistant. The main purpose of ASERA is to help the user in quasar spectral recognition and redshift measurement. Furthermore it can also be used to recognize various types of spectra of stars, galaxies and AGNs (Active Galactic Nucleus). It is an interactive software allowing the user to visualize observed spectra, superimpose template spectra from the Sloan Digital Sky Survey (SDSS), and interactively access related spectral line information. It is an efficient and user-friendly toolkit for the accurate classification of spectra observed by LAMOST (the Large Sky Area Multi-object Fiber Spectroscopic Telescope). The toolkit is available in two modes: a Java standalone application and a Java applet. ASERA has a few functions, such as wavelength and flux scale setting, zoom in and out, redshift estimation, spectral line identification, which helps user to improve the spectral classification accuracy especially for low quality spectra and reduce the labor of eyeball check. The function and performance of this tool is displayed through the recognition of several quasar spectra and a late type stellar spectrum from the LAMOST Pilot survey. Its future expansion capabilities are discussed.

What Colour Is a Shadow?

ERIC Educational Resources Information Center

Hughes, S. W.

2009-01-01

What colour is a shadow? Black, grey, or some other colour? This article describes how to use a digital camera to test the hypothesis that a shadow under a clear blue sky has a blue tint. A white sheet of A4 paper was photographed in full sunlight and in shadow under a clear blue sky. The images were analysed using a shareware program called…

Fermilab Education: Data-based Investigations

Science.gov Websites

Cosmic Rays Study cosmic rays with data from classrooom cosmic ray detectors. CMS e-Lab Study CMS Data using the CMS e-Lab from I2U2. LIGO Study seismic activity with data from LIGO (Laser Interferometer data from D0 - an example of conservation of momentum. Sky Server Study data from the Sloan Digital Sky

Automated Meteor Detection by All-Sky Digital Camera Systems

NASA Astrophysics Data System (ADS)

Suk, Tomáš; Šimberová, Stanislava

2017-12-01

We have developed a set of methods to detect meteor light traces captured by all-sky CCD cameras. Operating at small automatic observatories (stations), these cameras create a network spread over a large territory. Image data coming from these stations are merged in one central node. Since a vast amount of data is collected by the stations in a single night, robotic storage and analysis are essential to processing. The proposed methodology is adapted to data from a network of automatic stations equipped with digital fish-eye cameras and includes data capturing, preparation, pre-processing, analysis, and finally recognition of objects in time sequences. In our experiments we utilized real observed data from two stations.

Digital Image Compression Using Artificial Neural Networks

NASA Technical Reports Server (NTRS)

Serra-Ricart, M.; Garrido, L.; Gaitan, V.; Aloy, A.

1993-01-01

The problem of storing, transmitting, and manipulating digital images is considered. Because of the file sizes involved, large amounts of digitized image information are becoming common in modern projects. Our goal is to described an image compression transform coder based on artificial neural networks techniques (NNCTC). A comparison of the compression results obtained from digital astronomical images by the NNCTC and the method used in the compression of the digitized sky survey from the Space Telescope Science Institute based on the H-transform is performed in order to assess the reliability of the NNCTC.

Data Processing Factory for the Sloan Digital Sky Survey

NASA Astrophysics Data System (ADS)

Stoughton, Christopher; Adelman, Jennifer; Annis, James T.; Hendry, John; Inkmann, John; Jester, Sebastian; Kent, Steven M.; Kuropatkin, Nickolai; Lee, Brian; Lin, Huan; Peoples, John, Jr.; Sparks, Robert; Tucker, Douglas; Vanden Berk, Dan; Yanny, Brian; Yocum, Dan

2002-12-01

The Sloan Digital Sky Survey (SDSS) data handling presents two challenges: large data volume and timely production of spectroscopic plates from imaging data. A data processing factory, using technologies both old and new, handles this flow. Distribution to end users is via disk farms, to serve corrected images and calibrated spectra, and a database, to efficiently process catalog queries. For distribution of modest amounts of data from Apache Point Observatory to Fermilab, scripts use rsync to update files, while larger data transfers are accomplished by shipping magnetic tapes commercially. All data processing pipelines are wrapped in scripts to address consecutive phases: preparation, submission, checking, and quality control. We constructed the factory by chaining these pipelines together while using an operational database to hold processed imaging catalogs. The science database catalogs all imaging and spectroscopic object, with pointers to the various external files associated with them. Diverse computing systems address particular processing phases. UNIX computers handle tape reading and writing, as well as calibration steps that require access to a large amount of data with relatively modest computational demands. Commodity CPUs process steps that require access to a limited amount of data with more demanding computations requirements. Disk servers optimized for cost per Gbyte serve terabytes of processed data, while servers optimized for disk read speed run SQLServer software to process queries on the catalogs. This factory produced data for the SDSS Early Data Release in June 2001, and it is currently producing Data Release One, scheduled for January 2003.

The Sixth Data Release of the Sloan Digital Sky Survey

NASA Astrophysics Data System (ADS)

Adelman-McCarthy, Jennifer K.; Agüeros, Marcel A.; Allam, Sahar S.; Allende Prieto, Carlos; Anderson, Kurt S. J.; Anderson, Scott F.; Annis, James; Bahcall, Neta A.; Bailer-Jones, C. A. L.; Baldry, Ivan K.; Barentine, J. C.; Bassett, Bruce A.; Becker, Andrew C.; Beers, Timothy C.; Bell, Eric F.; Berlind, Andreas A.; Bernardi, Mariangela; Blanton, Michael R.; Bochanski, John J.; Boroski, William N.; Brinchmann, Jarle; Brinkmann, J.; Brunner, Robert J.; Budavári, Tamás; Carliles, Samuel; Carr, Michael A.; Castander, Francisco J.; Cinabro, David; Cool, R. J.; Covey, Kevin R.; Csabai, István; Cunha, Carlos E.; Davenport, James R. A.; Dilday, Ben; Doi, Mamoru; Eisenstein, Daniel J.; Evans, Michael L.; Fan, Xiaohui; Finkbeiner, Douglas P.; Friedman, Scott D.; Frieman, Joshua A.; Fukugita, Masataka; Gänsicke, Boris T.; Gates, Evalyn; Gillespie, Bruce; Glazebrook, Karl; Gray, Jim; Grebel, Eva K.; Gunn, James E.; Gurbani, Vijay K.; Hall, Patrick B.; Harding, Paul; Harvanek, Michael; Hawley, Suzanne L.; Hayes, Jeffrey; Heckman, Timothy M.; Hendry, John S.; Hindsley, Robert B.; Hirata, Christopher M.; Hogan, Craig J.; Hogg, David W.; Hyde, Joseph B.; Ichikawa, Shin-ichi; Ivezić, Željko; Jester, Sebastian; Johnson, Jennifer A.; Jorgensen, Anders M.; Jurić, Mario; Kent, Stephen M.; Kessler, R.; Kleinman, S. J.; Knapp, G. R.; Kron, Richard G.; Krzesinski, Jurek; Kuropatkin, Nikolay; Lamb, Donald Q.; Lampeitl, Hubert; Lebedeva, Svetlana; Lee, Young Sun; French Leger, R.; Lépine, Sébastien; Lima, Marcos; Lin, Huan; Long, Daniel C.; Loomis, Craig P.; Loveday, Jon; Lupton, Robert H.; Malanushenko, Olena; Malanushenko, Viktor; Mandelbaum, Rachel; Margon, Bruce; Marriner, John P.; Martínez-Delgado, David; Matsubara, Takahiko; McGehee, Peregrine M.; McKay, Timothy A.; Meiksin, Avery; Morrison, Heather L.; Munn, Jeffrey A.; Nakajima, Reiko; Neilsen, Eric H., Jr.; Newberg, Heidi Jo; Nichol, Robert C.; Nicinski, Tom; Nieto-Santisteban, Maria; Nitta, Atsuko; Okamura, Sadanori; Owen, Russell; Oyaizu, Hiroaki; Padmanabhan, Nikhil; Pan, Kaike; Park, Changbom; Peoples, John, Jr.; Pier, Jeffrey R.; Pope, Adrian C.; Purger, Norbert; Raddick, M. Jordan; Re Fiorentin, Paola; Richards, Gordon T.; Richmond, Michael W.; Riess, Adam G.; Rix, Hans-Walter; Rockosi, Constance M.; Sako, Masao; Schlegel, David J.; Schneider, Donald P.; Schreiber, Matthias R.; Schwope, Axel D.; Seljak, Uroš; Sesar, Branimir; Sheldon, Erin; Shimasaku, Kazu; Sivarani, Thirupathi; Allyn Smith, J.; Snedden, Stephanie A.; Steinmetz, Matthias; Strauss, Michael A.; SubbaRao, Mark; Suto, Yasushi; Szalay, Alexander S.; Szapudi, István; Szkody, Paula; Tegmark, Max; Thakar, Aniruddha R.; Tremonti, Christy A.; Tucker, Douglas L.; Uomoto, Alan; Vanden Berk, Daniel E.; Vandenberg, Jan; Vidrih, S.; Vogeley, Michael S.; Voges, Wolfgang; Vogt, Nicole P.; Wadadekar, Yogesh; Weinberg, David H.; West, Andrew A.; White, Simon D. M.; Wilhite, Brian C.; Yanny, Brian; Yocum, D. R.; York, Donald G.; Zehavi, Idit; Zucker, Daniel B.

2008-04-01

This paper describes the Sixth Data Release of the Sloan Digital Sky Survey. With this data release, the imaging of the northern Galactic cap is now complete. The survey contains images and parameters of roughly 287 million objects over 9583 deg2, including scans over a large range of Galactic latitudes and longitudes. The survey also includes 1.27 million spectra of stars, galaxies, quasars, and blank sky (for sky subtraction) selected over 7425 deg2. This release includes much more stellar spectroscopy than was available in previous data releases and also includes detailed estimates of stellar temperatures, gravities, and metallicities. The results of improved photometric calibration are now available, with uncertainties of roughly 1% in g, r, i, and z, and 2% in u, substantially better than the uncertainties in previous data releases. The spectra in this data release have improved wavelength and flux calibration, especially in the extreme blue and extreme red, leading to the qualitatively better determination of stellar types and radial velocities. The spectrophotometric fluxes are now tied to point-spread function magnitudes of stars rather than fiber magnitudes. This gives more robust results in the presence of seeing variations, but also implies a change in the spectrophotometric scale, which is now brighter by roughly 0.35 mag. Systematic errors in the velocity dispersions of galaxies have been fixed, and the results of two independent codes for determining spectral classifications and redshifts are made available. Additional spectral outputs are made available, including calibrated spectra from individual 15 minute exposures and the sky spectrum subtracted from each exposure. We also quantify a recently recognized underestimation of the brightnesses of galaxies of large angular extent due to poor sky subtraction; the bias can exceed 0.2 mag for galaxies brighter than r = 14 mag.

VizieR Online Data Catalog: WISE All-Sky Data Release (Cutri+ 2012)

NASA Astrophysics Data System (ADS)

Cutri, R. M.; et al.

2012-04-01

The Wide-field Infrared Survey Explorer (WISE; see Wright et al. 2010AJ....140.1868W) is a NASA Medium Class Explorer mission that conducted a digital imaging survey of the entire sky in the 3.4, 4.6, 12 and 22um mid-infrared bandpasses (hereafter W1, W2, W3 and W4). WISE will produce and release to the world astronomical and educational communities and general public a digital Image Atlas covering the sky in the four survey bands, and a reliable Source Catalog containing accurate photometry and astrometry for over 300 million objects. The WISE Catalog and Atlas will enable a broad variety of research efforts ranging from the search for the closest stars and brown dwarfs to the most luminous galaxies in the Universe. WISE science data products will serve as an important reference data set for planning observations and interpreting data obtained with future ground and space-borne observatories, such as JWST. WISE was launched on 2009-12-14 from Vandenberg SLC2W. (1 data file).

Dark Skies Awareness Programs for the International Year of Astronomy

NASA Astrophysics Data System (ADS)

Walker, C. E.; Pompea, S. M.

2008-12-01

The loss of a dark night sky as a natural resource is a growing concern. It impacts not only astronomical research, but also our environment in terms of ecology, health, safety, economics and energy conservation. For this reason, "Dark Skies are a Universal Resource" is a cornerstone project for the U.S. International Year of Astronomy (IYA) program in 2009. Its goal is to raise public awareness of the impact of artificial lighting on local environments by getting people involved in a variety of dark skies-related programs. These programs focus on citizen-scientist sky-brightness monitoring programs, a planetarium show, podcasting, social networking, a digital photography contest, the Good Neighbor Lighting Program, Earth Hour, National Dark Skies Week, a traveling exhibit, a video tutorial, Dark Skies Discovery Sites, Astronomy Nights in the (National) Parks, Sidewalk Astronomy, and a Quiet Skies program. Many similar programs are available internationally through the "Dark Skies Awareness" Global Cornerstone Project. Working groups for both the national and international dark skies cornerstone projects are being chaired by the National Optical Astronomy Observatory (NOAO). The presenters from NOAO will provide the "know-how" and the means for session participants to become community advocates in promoting Dark Skies programs as public events at their home institutions. Participants will be able to get information on jump-starting their education programs through the use of well-developed instructional materials and kits. For more information, visit http://astronomy2009.us/darkskies/ and http://www.darkskiesawareness.org/.

Preferred color correction for digital LCD TVs

NASA Astrophysics Data System (ADS)

Kim, Kyoung Tae; Kim, Choon-Woo; Ahn, Ji-Young; Kang, Dong-Woo; Shin, Hyun-Ho

2009-01-01

Instead of colorimetirc color reproduction, preferred color correction is applied for digital TVs to improve subjective image quality. First step of the preferred color correction is to survey the preferred color coordinates of memory colors. This can be achieved by the off-line human visual tests. Next step is to extract pixels of memory colors representing skin, grass and sky. For the detected pixels, colors are shifted towards the desired coordinates identified in advance. This correction process may result in undesirable contours on the boundaries between the corrected and un-corrected areas. For digital TV applications, the process of extraction and correction should be applied in every frame of the moving images. This paper presents a preferred color correction method in LCH color space. Values of chroma and hue are corrected independently. Undesirable contours on the boundaries of correction are minimized. The proposed method change the coordinates of memory color pixels towards the target color coordinates. Amount of correction is determined based on the averaged coordinate of the extracted pixels. The proposed method maintains the relative color difference within memory color areas. Performance of the proposed method is evaluated using the paired comparison. Results of experiments indicate that the proposed method can reproduce perceptually pleasing images to viewers.

Can We Build an Open-Science Model to Fund Young, Risky, Blue-Sky Research? First Insights into Funding Geoscientists Via Thinkable.Org

NASA Astrophysics Data System (ADS)

McNeil, B.

2014-12-01

Some of the biggest discoveries and advances in geoscience research have come from purely curiosity-driven, blue-sky research. Marine biologist Osamu Shimomura's discovery of Green-Fluorecent Protein (GFP) in the 1960s during his postdoc is just one example, which came about through his interest and pursuit of how certain jellyfish bioluminescence. His discovery would eventually revolutionise medicine, culminating in a Nobel Prize in Chemistry in 2008. Despite the known importance of "blue-sky" research that doesn't have immediate commercial or social applications, it continues to struggle for funding from both government and industry. Success rates for young scientists also continue to decline within the government competitive granting models due to the importance of track records, yet history tells us that young scientists tend to come up with science's greatest discoveries. The digital age however, gives us a new opportunity to create an alternative and sustainable funding model for young, risky, blue-sky science that tends not to be supported by governments and industry anymore. Here I will discuss how new digital platforms empower researchers and organisations to showcase their research using video, allowing wider community engagment and funding that can be used to directly support young, risky, blue-sky research that is so important to the future of science. I will then talk about recent experience with this model from some ocean researchers who used a new platform called thinkable.org to showcase and raise funding via the public.

Design of the Digital Sky Survey DA and online system: A case history in the use of computer aided tools for data acquisition system design

NASA Astrophysics Data System (ADS)

Petravick, D.; Berman, E.; Nicinski, T.; Rechenmacher, R.; Oleynik, G.; Pordes, R.; Stoughton, C.

1991-06-01

As part of its expanding Astrophysics program, Fermilab is participating in the Digital Sky Survey (DSS). Fermilab is part of a collaboration involving University of Chicago, Princeton University, and the Institute of Advanced Studies (at Princeton). The DSS main results will be a photometric imaging survey and a redshift survey of galaxies and color-selected quasars over pi steradians of the Northern Galactic Cap. This paper focuses on our use of Computer Aided Software Engineering (CASE) in specifying the data system for DSS. Extensions to standard methodologies were necessary to compensate for tool shortcomings and to improve communication amongst the collaboration members. One such important extension was the incorporation of CASE information into the specification document.

Exploring the Digital Universe with Europe's Astrophysical Virtual Observatory

NASA Astrophysics Data System (ADS)

2001-12-01

N° 73-2001 - Paris, 5 December 2001 The aim of AVO is to give astronomers instant access to the vast databanks now being built up by the world's observatories and forming what is in effect a "digital sky". Using AVO astronomers will be able, for example, to retrieve the elusive traces of the passage of an asteroid as it passes the Earth and so predict its future path and perhaps warn of a possible impact. When a giant star comes to the end of its life in a cataclysmic explosion called a supernova, they will be able to access the digital sky and pinpoint the star shortly before it exploded, adding invaluable data to the study of the evolution of stars. Modern observatories observe the sky continuously and data accumulates remorselessly in the digital archives. The growth rate is impressive and many hundreds of terabytes of data -corresponding to many thousands of billions of pixels - are already available to scientists. The real sky is being digitally reconstructed in the databanks. The volume and complexity of data and information available to astronomers are overwhelming. Hence the problem of how astronomers can possibly manage, distribute and analyse this great wealth of data. The Astrophysical Virtual Observatory will enable them to meet the challenge and "put the Universe online". AVO is a three-year project, funded by the European Commission under its Research and Technological Development (RTD) scheme, to design and implement a virtual observatory for the European astronomical community. The Commission has awarded a contract valued at EUR 4m for the project, starting on 15 November. AVO will provide software tools to enable astronomers to access the multi-wavelength data archives over the Internet and so give them the capability to resolve fundamental questions about the Universe by probing the digital sky. Equivalent searches of the "real" sky would, in comparison, both be prohibitively costly and take far too long. Towards a Global Virtual Observatory The need for virtual observatories has also been recognised by other astronomical communities. The National Science Foundation in the USA has awarded $10 million (EUR 11.4 m) for a National Virtual Observatory (NVO). The AVO project team has formed a close alliance with the NVO and both teams have representatives on each other's committees. It is clear to the NVO and AVO communities that there are no intrinsic boundaries to the virtual observatory concept and that all astronomers should be working towards a truly global virtual observatory that will enable new science to be carried out on the wealth of astronomical data held in the growing number of first-class international astronomical archives. AVO involves six partner organisations led by the European Southern Observatory (ESO) in Munich. The other partner organisations are the European Space Agency (ESA), the United Kingdom's ASTROGRID consortium, the CNRS-supported Centre de Données Astronomiques de Strasbourg (CDS) at the University Louis Pasteur in Strasbourg, the CNRS-supported TERAPIX astronomical data centre at the Institut d'Astrophysique in Paris and the Jodrell Bank Observatory at the University of Manchester. Note for editors A 13-minute background video (broadcast PAL) is available from ESO PR and the Hubble European Space Agency Information Centre (addresses below). It will also be transmitted via satellite on Wednesday 12 December 2001 from 12:00 to 12:15 CET on the ESA TV Service: http://television.esa.int

Astronomy Meets the Environmental Sciences: Using GLOBE at Night Data

NASA Astrophysics Data System (ADS)

Barringer, D.; Walker, C. E.; Pompea, S. M.; Sparks, R. T.

2011-09-01

The GLOBE at Night database now contains over 52,000 observations from the five annual two-week campaigns. It can be used as a resource to explore various issues related to light pollution and our environment. Students can compare data over time to look for changes and trends. For example, they can compare the data to population density or with nighttime photography and spectroscopy of lights. The data can be used in a lighting survey, to search for dark sky oases or to monitor ordinance compliance. Students can study effects of light pollution on animals, plants, human health, safety, security, energy consumption, and cost. As an example, we used data from the GLOBE at Night project and telemetry tracking data of lesser long-nosed bats obtained by the Arizona Game and Fish Department to study the effects of light pollution on the flight paths of the bats between their day roosts and night foraging areas around the city of Tucson, AZ. With the visual limiting magnitude data from GLOBE at Night, we ran a compositional analysis with respect to the bats' flight paths to determine whether the bats were selecting for or against flight through regions of particular night sky brightness levels. We found that the bats selected for the regions in which the limiting sky magnitudes fell between the ranges of 2.8-3.0 to 3.6-3.8 and 4.4-4.6 to 5.0-5.2, suggesting that the lesser long-nosed bat can tolerate a fair degree of urbanization. We also compared this result to contour maps created with digital Sky Quality Meter (http://www.unihedron.com) data.

Distribution to the Astronomy Community of the Compressed Digitized Sky Survey

NASA Astrophysics Data System (ADS)

Postman, Marc

1996-03-01

The Space Telescope Science Institute has compressed an all-sky collection of ground-based images and has printed the data on a two volume, 102 CD-ROM disc set. The first part of the survey (containing images of the southern sky) was published in May 1994. The second volume (containing images of the northern sky) was published in January 1995. Software which manages the image retrieval is included with each volume. The Astronomical Society of the Pacific (ASP) is handling the distribution of the lOx compressed data and has sold 310 sets as of October 1996. ASP is also handling the distribution of the recently published 100x version of the northern sky survey which is publicly available at a low cost. The target markets for the 100x compressed data set are the amateur astronomy community, educational institutions, and the general public. During the next year, we plan to publish the first version of a photometric calibration database which will allow users of the compressed sky survey to determine the brightness of stars in the images.

Passive optical sensing of atmospheric polarization for GPS denied operations

NASA Astrophysics Data System (ADS)

Aycock, Todd; Lompado, Art; Wolz, Troy; Chenault, David

2016-05-01

There is a rapidly growing need for position, navigation, and timing (PNT) capability that remains effective when GPS is degraded or denied. Naturally occurring sky polarization was used as long ago as the Vikings for navigation purposes. With current polarimetric sensors, the additional polarization information measured by these sensors can be used to increase the accuracy and the availability of this technique. The Sky Polarization Azimuth Sensing System (SkyPASS) sensor measures this naturally occurring sky polarization to give absolute heading information to less than 0.1° and offers significant performance enhancement over digital compasses and sun sensors. SkyPASS has been under development for some time for terrestrial applications, but use above the atmosphere may be possible and the performance specifications and SWAP are attractive for use as an additional pose sensor on a satellite. In this paper, we will describe the phenomenology, the sensor performance, and the latest test results of terrestrial SkyPASS; we will also discuss the potential for use above the atmosphere and the expected benefits and limitations.

Distribution to the Astronomy Community of the Compressed Digitized Sky Survey

NASA Technical Reports Server (NTRS)

Postman, Marc

1996-01-01

The Space Telescope Science Institute has compressed an all-sky collection of ground-based images and has printed the data on a two volume, 102 CD-ROM disc set. The first part of the survey (containing images of the southern sky) was published in May 1994. The second volume (containing images of the northern sky) was published in January 1995. Software which manages the image retrieval is included with each volume. The Astronomical Society of the Pacific (ASP) is handling the distribution of the lOx compressed data and has sold 310 sets as of October 1996. ASP is also handling the distribution of the recently published 100x version of the northern sky survey which is publicly available at a low cost. The target markets for the 100x compressed data set are the amateur astronomy community, educational institutions, and the general public. During the next year, we plan to publish the first version of a photometric calibration database which will allow users of the compressed sky survey to determine the brightness of stars in the images.

"Let There Be Night" Advocates Dark Skies

NASA Astrophysics Data System (ADS)

Bueter, Chuck

2008-05-01

Let There Be Night is an interactive planetarium program that supports a community-wide experiment to quantify local sky glow. In the planetarium, visitors will experience three aspects of light pollution--glare, sky glow, and light trespass--and decide whether and how to confront dark sky issues. Planetarians can select optional recorded stories and lessons to complement live demonstrations or star talks. As a companion experiment, students in grades 3-8 from one school district will then submit their backyard observations of Orion's limiting magnitude to the 2009 Globe at Night star hunt while small student teams concurrently quantify sky glow from each schoolyard with hand-held meters. After mapping their results and having classroom discussions, students will present their findings to the School Board. Material compiled and created for the program will be available for other dark sky advocates at www.LetThereBeNight.com, while large digital files will be distributed on disk through two planetarium associations. A 2008 Toyota TAPESTRY grant has enticed significant professional support, additional funding, and in-kind contributions.

A Nearby Old Halo White Dwarf Candidate from the Sloan Digital Sky Survey

DTIC Science & Technology

2008-07-01

Mi- cron All Sky Survey ( 2MASS ; Skrutskie et al. 2006) within 2′′ of the expected position of J1102+4113 at that epoch. To measure the flux in this...feature, we retrieved the 2MASS Atlas images covering this object, measured 3′′ radius aperture magnitudes 78 H A L L E T A L . V ol.136 Table 1...POSS2 50094.9138 . . . . . . . . . 18.41 . . . . . . . . . . . . . . . . . . 2MASS 50912.8346

More Observations in Schools for Promoting Astronomy and Sky Protection

NASA Astrophysics Data System (ADS)

Ros, Rosa M.

2015-03-01

In astronomy it is important to promote observation and the quality of the sky is essential for a good observation impact. It is important that children have a nice memory of their observations in a non-polluted sky. Using students as agents of change it is possible to promote good practice for sky protection in society.

Dark Skies Preservation through Responsible Lighting: the IYL2015 Quality Lighting Kit

NASA Astrophysics Data System (ADS)

Walker, Constance E.

2015-01-01

Poor quality lighting not only impedes astronomy research, but creates safety issues, affects human circadian sensitivities, disrupts ecosystems, and wastes more than a few billion dollars/year of energy in the USA alone. The United Nations-sanctioned the International Year of Light in 2015 (IYL2015) is providing an opportunity to increase public awareness of dark skies preservation, quality lighting and energy conservation. The Education and Public Outreach (EPO) group at the National Optical Astronomy Observatory (NOAO) has received a small grant through the International Astronomical Union (IAU) to produce official 'Quality Lighting Teaching Kits' for the IYL2015 cornerstone theme, 'Cosmic Light'. These kits will emphasize the use of proper optical design in achieving quality lighting that promotes both energy efficiency and energy conservation of an endangered natural resource, our dark skies. The concepts and practice of 'quality lighting' will be explored through demonstrations, hands-on/minds-on activities, formative assessment probes, and engineering design projects that explore basic principles of optics and the physics of light. The impact of the kits will be amplified by providing professional development using tutorial videos created at NOAO and conducting question and answer sessions via Google+ Hangouts for the outreach volunteers. The quality lighting education program will leverage NOAO EPO's work in the last ten years on lighting and optics education (e.g., the IAU 'Dark Skies Africa', APS 'Dark Skies Yuma' and 'Hands-On Optics' programs). NOAO's partners are CIE (International Commission on Illumination), IDA (International Dark-Sky Association) and SPIE (International Society for Optics and Photonics), as well as the IAU Office of Astronomy for Development, Galileo Teacher Training Program, Universe Awareness, and Global Hands-on Universe. Their networks will disseminate the program and kits to formal and informal audiences worldwide. The impact sought is a change in knowledge, attitude, and behavior in each community by learning how to light responsibly, improving the quality of life in 'illuminating' ways.

Our Light or Starlight? Citizen Science, Public Involvement and You

NASA Astrophysics Data System (ADS)

Walker, Constance E.

2010-10-01

With half of the world's population now living in cities, many urban dwellers have never experienced the wonderment of pristinely dark skies and maybe never will. Light pollution is obscuring people's long-standing natural heritage to view stars. The GLOBE at Night program (www.globeatnight.org) is an international citizen-science campaign to raise public awareness of the impact of light pollution by encouraging everyone everywhere to measure local levels of night sky brightness and contribute observations online to a world map. In the last 5 years, GLOBE at Night has been the most productive public light pollution monitoring campaign, collecting over 52,000 observations in a two-week period annually. This year, during the moonless two weeks in March, the campaign set a record high of over 17,800 measurements from people in 86 countries. Foundational resources are available to facilitate the public's participation in promoting dark skies awareness. The GLOBE at Night website explains clearly the simple-to-participate-in 5 step program and offers background information and interactive games on key concepts. The program has been expanded to include trainings of the general public, but especially educators in schools, museums and science centers, in unique ways. Education kits for dark skies awareness have been distributed at the training workshops. The kit includes material for a light shielding demonstration, a digital Sky Quality Meter and ``Dark Skies Rangers'' activities. The activities are on how unshielded light wastes energy, how light pollution affects wildlife and how you can participate in a citizen-science star-hunt like GLOBE at Night. In addition, projects are being developed for what to do with the data once it is taken. The GLOBE at Night data from different years can be compared to look for trends over time or with population density maps. The data can also be used to search for dark sky oases or to monitor lighting ordinance compliance. Most recently the data has been compared with telemetry of the Lesser Long-Nose Bat near Tucson, Arizona to examine whether or not the bats are preferentially staying in darker areas. The presentation will highlight the education and outreach value of the program's resources and outcomes in communicating awareness with the public and attracting young people to study science.

GLOBE at Night: Raising Public Awareness and Involvement through Citizen Science

NASA Astrophysics Data System (ADS)

Walker, C. E.; Pompea, S. M.; Sparks, R. T.

2010-12-01

With half of the world’s population now living in cities, many urban dwellers have never experienced the wonderment of pristinely dark skies and maybe never will. Light pollution is obscuring people’s long-standing natural heritage to view stars. The GLOBE at Night program (www.globeatnight.org) is an international citizen-science campaign to raise public awareness of the impact of light pollution by encouraging everyone everywhere to measure local levels of night sky brightness and contribute observations online to a world map. In the last 5 years, GLOBE at Night has been the most productive public light pollution monitoring campaign, collecting over 52,000 observations in a two-week period annually. This year, during the moonless two weeks in March, the campaign set a record high of over 17,800 measurements from people in 86 countries. Foundational resources are available to facilitate the public’s participation in promoting dark skies awareness. The GLOBE at Night website explains clearly the simple-to-participate-in 5 step program and offers background information and interactive games on key concepts. The program has been expanded to include trainings of the general public, but especially educators in schools, museums and science centers, in unique ways. Education kits for dark skies awareness have been distributed at the training workshops. The kit includes material for a light shielding demonstration, a digital Sky Quality Meter and “Dark Skies Rangers” activities. The activities are on how unshielded light wastes energy, how light pollution affects wildlife and how you can participate in a citizen-science star-hunt like GLOBE at Night. In addition, projects are being developed for what to do with the data once it is taken. The GLOBE at Night data from different years can be compared to look for trends over time or with population density maps. The data can also be used to search for dark sky oases or to monitor lighting ordinance compliance. Most recently the data has been compared with telemetry of the Lesser Long-Nose Bat near Tucson, Arizona to examine whether or not the bats are preferentially staying in darker areas. The presentation will highlight the education and outreach value of the program’s resources and outcomes in communicating awareness with the public and attracting young people to study science.

Molecular hydrogen absorption systems in Sloan Digital Sky Survey

NASA Astrophysics Data System (ADS)

Balashev, S. A.; Klimenko, V. V.; Ivanchik, A. V.; Varshalovich, D. A.; Petitjean, P.; Noterdaeme, P.

2014-05-01

We present a systematic search for molecular hydrogen absorption systems at high redshift in quasar spectra from the Sloan Digital Sky Survey (SDSS)-II Data Release 7 and SDSS-III Data Release 9. We have selected candidates using a modified profile fitting technique taking into account that the Lyα forest can effectively mimic H2 absorption systems at the resolution of SDSS data. To estimate the confidence level of the detections, we use two methods: a Monte Carlo sampling and an analysis of control samples. The analysis of control samples allows us to define regions of the spectral quality parameter space where H2 absorption systems can be confidently identified. We find that H2 absorption systems with column densities log NH2 > 19 can be detected in only less than 3 per cent of SDSS quasar spectra. We estimate the upper limit on the detection rate of saturated H2 absorption systems (NH2 > 19) in damped Lyα (DLA) systems to be about 7 per cent. We provide a sample of 23 confident H2 absorption system candidates that would be interesting to follow up with high-resolution spectrographs. There is a 1σ r - i colour excess and non-significant AV extinction excess in quasar spectra with an H2 candidate compared to standard DLA-bearing quasar spectra. The equivalent widths of C II, Si II and Al III (but not Fe II) absorptions associated with H2 candidate DLAs are larger compared to standard DLAs. This is probably related to a larger spread in velocity of the absorption lines in the H2-bearing sample.

NIXNOX project: Sites in Spain where citizens can enjoy dark starry skies

NASA Astrophysics Data System (ADS)

Zamorano, J.; de Miguel, A. Sánchez; Alfaro, E.; Martínez-Delgado, D.; Ocaña, F.; Castaño, J. Gómez; Nievas, M.

2015-03-01

The NIXNOX project, sponsored by the Spanish Astronomical Society, is a Pro-Am collaboration with the aim of finding sites with dark skies. All sky data of the night sky brightness is being obtained by amateur astronomers with Sky Quality Meter (SQM) photometers. We are not looking for remote locations because the places should be easily accessible by people with children. Our goal is to motivate citizens to observe the night sky. NIXNOX will provide information to answer the question: where can I go to observe the stars with my family?

[Galaxy/quasar classification based on nearest neighbor method].

PubMed

Li, Xiang-Ru; Lu, Yu; Zhou, Jian-Ming; Wang, Yong-Jun

2011-09-01

With the wide application of high-quality CCD in celestial spectrum imagery and the implementation of many large sky survey programs (e. g., Sloan Digital Sky Survey (SDSS), Two-degree-Field Galaxy Redshift Survey (2dF), Spectroscopic Survey Telescope (SST), Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) program and Large Synoptic Survey Telescope (LSST) program, etc.), celestial observational data are coming into the world like torrential rain. Therefore, to utilize them effectively and fully, research on automated processing methods for celestial data is imperative. In the present work, we investigated how to recognizing galaxies and quasars from spectra based on nearest neighbor method. Galaxies and quasars are extragalactic objects, they are far away from earth, and their spectra are usually contaminated by various noise. Therefore, it is a typical problem to recognize these two types of spectra in automatic spectra classification. Furthermore, the utilized method, nearest neighbor, is one of the most typical, classic, mature algorithms in pattern recognition and data mining, and often is used as a benchmark in developing novel algorithm. For applicability in practice, it is shown that the recognition ratio of nearest neighbor method (NN) is comparable to the best results reported in the literature based on more complicated methods, and the superiority of NN is that this method does not need to be trained, which is useful in incremental learning and parallel computation in mass spectral data processing. In conclusion, the results in this work are helpful for studying galaxies and quasars spectra classification.

VizieR Online Data Catalog: Abundances of LAMOST giants from APOGEE DR12 (Ho+, 2017)

NASA Astrophysics Data System (ADS)

Ho, A. Y. Q.; Ness, M. K.; Hogg, D. W.; Rix, H.-W.; Liu, C.; Yang, F.; Zhang, Y.; Hou, Y.; Wang, Y.

2017-09-01

The Large sky Area Multi-Object Spectroscopic Telescope (LAMOST) is a low-resolution (R~1800) optical (3650-9000Å) spectroscopic survey. APOGEE is a high-resolution (R~22500), high-S/N (S/N~100), H-band (15200-16900Å) spectroscopic survey, part of the Sloan Digital Sky Survey III. Observations are conducted using a 300 fiber spectrograph on the 2.5m Sloan Telescope at the Apache Point Observatory (APO) in Sunspot, New Mexico (USA). (1 data file).

Horizon Brightness Revisited: Measurements and a Model of Clear-Sky Radiances

DTIC Science & Technology

1994-07-20

Clear daytime skies persistently display a subtle local maximum of radiance near the astronomical horizon. Spectroradiometry and digital image analysis confirm this maximum’s reality, and they show that its angular width and elevation vary with solar elevation, azimuth relative to the Sun, and aerosol optical depth. Many existing models of atmospheric scattering do not generate this near-horizon radiance maximum, but a simple second-order scattering model does, and it reproduces many of the maximum’s details.

After the Explosion: Investigating Supernova Sites

NASA Image and Video Library

2015-03-26

A new study analyzes several sites where dead stars once exploded. The explosions, called Type Ia supernovae, occurred within galaxies, six of which are shown in these images from the Sloan Digital Sky Survey.

Using Neural Networks to Classify Digitized Images of Galaxies

NASA Astrophysics Data System (ADS)

Goderya, S. N.; McGuire, P. C.

2000-12-01

Automated classification of Galaxies into Hubble types is of paramount importance to study the large scale structure of the Universe, particularly as survey projects like the Sloan Digital Sky Survey complete their data acquisition of one million galaxies. At present it is not possible to find robust and efficient artificial intelligence based galaxy classifiers. In this study we will summarize progress made in the development of automated galaxy classifiers using neural networks as machine learning tools. We explore the Bayesian linear algorithm, the higher order probabilistic network, the multilayer perceptron neural network and Support Vector Machine Classifier. The performance of any machine classifier is dependant on the quality of the parameters that characterize the different groups of galaxies. Our effort is to develop geometric and invariant moment based parameters as input to the machine classifiers instead of the raw pixel data. Such an approach reduces the dimensionality of the classifier considerably, and removes the effects of scaling and rotation, and makes it easier to solve for the unknown parameters in the galaxy classifier. To judge the quality of training and classification we develop the concept of Mathews coefficients for the galaxy classification community. Mathews coefficients are single numbers that quantify classifier performance even with unequal prior probabilities of the classes.

Continuing Long Term Optical and Infrared Reverberation Mapping of 17 Sloan Digital Sky Survey Quasars

NASA Astrophysics Data System (ADS)

Gorjian, Varoujan; Barth, Aaron; Brandt, Niel; Dawson, Kyle; Green, Paul; Ho, Luis; Horne, Keith; Jiang, Linhua; McGreer, Ian; Schneider, Donald; Shen, Yue; Tao, Charling

2018-05-01

Previous Spitzer reverberation monitoring projects searching for UV/optical light absorbed and re-emitted in the IR by dust have been limited to low luminosity active galactic nuclei (AGN) that could potentially show reverberation within a single cycle ( 1 year). Cycle 11-12's two year baseline allowed for the reverberation mapping of 17 high-luminosity quasars from the Sloan Digital Sky Survey Reverberation Mapping project. We continued this monitoring in Cycle 13 and now propose to extend this program in Cycle 14. By combining ground-based monitoring from Pan-STARRS, CFHT, and Steward Observatory telescopes with Spitzer data we have for the first time detected dust reverberation in quasars. By continuing observations with this unqiue combination of resources we should detect reverberation in more objects and reduce the uncertainties for the remaining sources.

SAGITTARIUS STREAM THREE-DIMENSIONAL KINEMATICS FROM SLOAN DIGITAL SKY SURVEY STRIPE 82

DOE Office of Scientific and Technical Information (OSTI.GOV)

Koposov, Sergey E.; Belokurov, Vasily; Evans, N. Wyn

2013-04-01

Using multi-epoch observations of the Stripe 82 region from the Sloan Digital Sky Survey (SDSS), we measure precise statistical proper motions of the stars in the Sagittarius (Sgr) stellar stream. The multi-band photometry and SDSS radial velocities allow us to efficiently select Sgr members and thus enhance the proper-motion precision to {approx}0.1 mas yr{sup -1}. We measure separately the proper motion of a photometrically selected sample of the main-sequence turn-off stars, as well as spectroscopically selected Sgr giants. The data allow us to determine the proper motion separately for the two Sgr streams in the south found in Koposov etmore » al. Together with the precise velocities from SDSS, our proper motions provide exquisite constraints of the three-dimensional motions of the stars in the Sgr streams.« less

A method for selecting M dwarfs with an increased likelihood of unresolved ultracool companionship

NASA Astrophysics Data System (ADS)

Cook, N. J.; Pinfield, D. J.; Marocco, F.; Burningham, B.; Jones, H. R. A.; Frith, J.; Zhong, J.; Luo, A. L.; Qi, Z. X.; Lucas, P. W.; Gromadzki, M.; Day-Jones, A. C.; Kurtev, R. G.; Guo, Y. X.; Wang, Y. F.; Bai, Y.; Yi, Z. P.; Smart, R. L.

2016-04-01

Locating ultracool companions to M dwarfs is important for constraining low-mass formation models, the measurement of substellar dynamical masses and radii, and for testing ultracool evolutionary models. We present an optimized method for identifying M dwarfs which may have unresolved ultracool companions. We construct a catalogue of 440 694 M dwarf candidates, from Wide-Field Infrared Survey Explorer, Two Micron All-Sky Survey and Sloan Digital Sky Survey, based on optical- and near-infrared colours and reduced proper motion. With strict reddening, photometric and quality constraints we isolate a subsample of 36 898 M dwarfs and search for possible mid-infrared M dwarf + ultracool dwarf candidates by comparing M dwarfs which have similar optical/near-infrared colours (chosen for their sensitivity to effective temperature and metallicity). We present 1082 M dwarf + ultracool dwarf candidates for follow-up. Using simulated ultracool dwarf companions to M dwarfs, we estimate that the occurrence of unresolved ultracool companions amongst our M dwarf + ultracool dwarf candidates should be at least four times the average for our full M dwarf catalogue. We discuss possible contamination and bias and predict yields of candidates based on our simulations.

On the limitations of statistical absorption studies with the Sloan Digital Sky Surveys I-III

NASA Astrophysics Data System (ADS)

Lan, Ting-Wen; Ménard, Brice; Baron, Dalya; Johnson, Sean; Poznanski, Dovi; Prochaska, J. Xavier; O'Meara, John M.

2018-07-01

We investigate the limitations of statistical absorption measurements with the Sloan Digital Sky Survey (SDSS) optical spectroscopic surveys. We show that changes in the data reduction strategy throughout different data releases have led to a better accuracy at long wavelengths, in particular for sky line subtraction, but a degradation at short wavelengths with the emergence of systematic spectral features with an amplitude of about 1 per cent. We show that these features originate from inaccuracy in the fitting of modelled F-star spectra used for flux calibration. The best-fitting models for those stars are found to systematically overestimate the strength of metal lines and underestimate that of Lithium. We also identify the existence of artefacts due to masking and interpolation procedures at the wavelengths of the hydrogen Balmer series leading to the existence of artificial Balmer α absorption in all SDSS optical spectra. All these effects occur in the rest frame of the standard stars and therefore present Galactic longitude variations due to the rotation of the Galaxy. We demonstrate that the detection of certain weak absorption lines reported in the literature is solely due to calibration effects. Finally, we discuss new strategies to mitigate these issues.

Color Separation of Galaxy Types in the Sloan Digital Sky Survey Imaging Data

NASA Astrophysics Data System (ADS)

Strateva, Iskra; Ivezić, Željko; Knapp, Gillian R.; Narayanan, Vijay K.; Strauss, Michael A.; Gunn, James E.; Lupton, Robert H.; Schlegel, David; Bahcall, Neta A.; Brinkmann, Jon; Brunner, Robert J.; Budavári, Tamás; Csabai, István; Castander, Francisco Javier; Doi, Mamoru; Fukugita, Masataka; Győry, Zsuzsanna; Hamabe, Masaru; Hennessy, Greg; Ichikawa, Takashi; Kunszt, Peter Z.; Lamb, Don Q.; McKay, Timothy A.; Okamura, Sadanori; Racusin, Judith; Sekiguchi, Maki; Schneider, Donald P.; Shimasaku, Kazuhiro; York, Donald

2001-10-01

We study the optical colors of 147,920 galaxies brighter than g*=21, observed in five bands by the Sloan Digital Sky Survey (SDSS) over ~100 deg2 of high Galactic latitude sky along the celestial equator. The distribution of galaxies in the g*-r* versus u*-g* color-color diagram is strongly bimodal, with an optimal color separator of u*-r*=2.22. We use visual morphology and spectral classification of subsamples of 287 and 500 galaxies, respectively, to show that the two peaks correspond roughly to early- (E, S0, and Sa) and late-type (Sb, Sc, and Irr) galaxies, as expected from their different stellar populations. We also find that the colors of galaxies are correlated with their radial profiles, as measured by the concentration index and by the likelihoods of exponential and de Vaucouleurs' profile fits. While it is well known that late-type galaxies are bluer than early-type galaxies, this is the first detection of a local minimum in their color distribution. In all SDSS bands, the counts versus apparent magnitude relations for the two color types are significantly different and demonstrate that the fraction of blue galaxies increases toward the faint end.

The Pan-STARRS1 Small Area Survey 2

NASA Astrophysics Data System (ADS)

Metcalfe, N.; Farrow, D. J.; Cole, S.; Draper, P. W.; Norberg, P.; Burgett, W. S.; Chambers, K. C.; Denneau, L.; Flewelling, H.; Kaiser, N.; Kudritzki, R.; Magnier, E. A.; Morgan, J. S.; Price, P. A.; Sweeney, W.; Tonry, J. L.; Wainscoat, R. J.; Waters, C.

2013-11-01

The Panoramic Survey Telescope and Rapid Response System 1 (Pan-STARRS1) survey is acquiring multi-epoch imaging in five bands (gP1, rP1, iP1, zP1, yP1) over the entire sky north of declination -30° (the 3π survey). In 2011 July a test area of about 70 deg2 was observed to the expected final depth of the main survey. In this, the first of a series of papers targeting the galaxy count and clustering properties of the combined multi-epoch test area data, we present a detailed investigation into the depth of the survey and the reliability of the Pan-STARRS1 analysis software. We show that the Pan-STARRS1 reduction software can recover the properties of fake sources, and show good agreement between the magnitudes measured by Pan-STARRS1 and those from Sloan Digital Sky Survey. We also examine the number of false detections apparent in the Pan-STARRS1 data. Our comparisons show that the test area survey is somewhat deeper than the Sloan Digital Sky Survey in all bands, and, in particular, the z band approaches the depth of the stacked Sloan Stripe 82 data.

Characterizing Sky Spectra Using SDSS BOSS Data

NASA Astrophysics Data System (ADS)

Florez, Lina Maria; Strauss, Michael A.

2018-01-01

In the optical/near-infrared spectra gathered by a ground-based telescope observing very faint sources, the strengths of the emission lines due to the Earth’s atmosphere can be many times larger than the fluxes of the sources we are interested in. Thus the limiting factor in faint-object spectroscopy is the degree to which systematics in the sky subtraction can be minimized. Longwards of 6000 Angstroms, the night-sky spectrum is dominated by multiple vibrational/rotational transitions of the OH radical from our upper atmosphere. While the wavelengths of these lines are the same in each sky spectrum, their relative strengths vary considerably as a function of time and position on the sky. The better we can model their strengths, the better we can hope to subtract them off. We expect that the strength of lines from common upper energy levels will be correlated with one another. We used flux-calibrated sky spectra from the Sloan Digital Sky Survey Baryon Oscillation Spectroscopic Survey (SDSS BOSS) to explore these correlations. Our aim is to use these correlations for creating improved sky subtraction algorithms for the Prime Focus Spectrograph (PFS) on the 8.2-meter Subaru Telescope. When PFS starts gathering data in 2019, it will be the most powerful multi-object spectrograph in the world. Since PFS will be gathering data on sources as faint as 24th magnitude and fainter, it's of upmost importance to be able to accurately measure and subtract sky spectra from the data that we receive.

Airborne geophysical surveys conducted in western Nebraska, 2010: contractor reports and data

USGS Publications Warehouse

,

2014-01-01

This report contains three contractor reports and data files for an airborne electromagnetic survey flown from June 28 to July 7, 2010. The first report; “SkyTEM Survey: Nebraska, USA, Data” describes data aquisition and processing from a time-domain electromagnetic and magnetic survey performed by SkyTEM Canada, Inc. (the North American SkyTEM subsidiary), in western Nebraska, USA. Digital data for this report are given in Appendix 1. The airborne geophysical data from the SkyTEM survey subsequently were processed and inverted by Aarhus Geophysics ApS, Aarhus, Denmark, to produce resistivity depth sections along each flight line. The result of that processing is described in two reports presented in Appendix 2, “Processing and inversion of SkyTEM data from USGS Area UTM–13” and “Processing and inversion of SkyTEM data from USGS Area UTM–14.” Funding for these surveys was provided by the North Platte Natural Resources District, the South Platte Natural Resources District, and the Twin Platte Natural Resources District, in Scottsbluff, Sidney, and North Platte, Nebraska, respectively. Any additional information concerning the geophysical data may be obtained from the U.S. Geological Survey Crustal Geophysics and Geochemistry Science Center, Denver Colorado.

THE BLUE TIP OF THE STELLAR LOCUS: MEASURING REDDENING WITH THE SLOAN DIGITAL SKY SURVEY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schlafly, Edward F.; Finkbeiner, Douglas P.; Juric, Mario

2010-12-10

We present measurements of reddening due to dust using the colors of stars in the Sloan Digital Sky Survey (SDSS). We measure the color of main-sequence turnoff stars by finding the 'blue tip' of the stellar locus: the prominent blue edge in the distribution of stellar colors. The method is sensitive to color changes of order 18, 12, 7, and 8 mmag of reddening in the colors u - g, g - r, r - i, and i - z, respectively, in regions measuring 90' by 14'. We present maps of the blue tip colors in each of these bandsmore » over the entire SDSS footprint, including the new dusty southern Galactic cap data provided by the SDSS-III. The results disfavor the best-fit O'Donnell and Cardelli et al. reddening laws, but are described well by a Fitzpatrick reddening law with R{sub V} = 3.1. The Schlegel et al. (SFD) dust map is found to trace the dust well, but overestimates reddening by factors of 1.4, 1.0, 1.2, and 1.4 in u - g, g - r, r - i, and i - z largely due to the adopted reddening law. In select dusty regions of the sky, we find evidence for problems in the SFD temperature correction. A dust map normalization difference of 15% between the Galactic north and south sky may be due to these dust temperature errors.« less

Analysis of web-related threats in ten years of logs from a scientific portal

NASA Astrophysics Data System (ADS)

Santos, Rafael D. C.; Grégio, André R. A.; Raddick, Jordan; Vattki, Vamsi; Szalay, Alex

2012-06-01

SkyServer is an Internet portal to data from the Sloan Digital Sky Survey, the largest online archive of astronomy data in the world. provides free access to hundreds of millions of celestial objects for science, education and outreach purposes. Logs of accesses to SkyServer comprise around 930 million hits, 140 million web services accesses and 170 million SQL submitted queries, collected over the past 10 years. These logs also contain indications of compromise attempts on the servers. In this paper, we show some threats that were detected in ten years of stored logs, and compare them with known threats in those years. Also, we present an analysis of the evolution of those threats over these years.

A wide-band, high-resolution spectrum analyzer

NASA Technical Reports Server (NTRS)

Wilck, H. C.; Quirk, M. P.; Grimm, M. J.

1985-01-01

A million-channel, 20 MHz-bandwidth, digital spectrum analyzer under evelopment for use in the SETI Sky Survey and other applications in the Deep Space Network is described. The analyzer digitizes an analog input, performs a 2(20)-point Radix-2, Fast Fourier Transform, accumulates the output power, and normalizes the output to remove frequency-dependent gain. The effective speed of the real-time hardware is 2.2 GigaFLOPS.

DASCH to Measure (and preserve) the Harvard Plates: Opening the ˜100-year Time Domain Astronomy Window

NASA Astrophysics Data System (ADS)

Grindlay, J.; Tang, S.; Simcoe, R.; Laycock, S.; Los, E.; Mink, D.; Doane, A.; Champine, G.

2009-08-01

The temporal Universe is now possible to study on previously inaccessible timescales of days to decades, over a full century, with the planned full-digitization of the Harvard plate collection. The Digital Access to a Sky Century @ Harvard (DASCH) project has developed the world's highest-speed precision plate scanner and the required software to digitize the ˜500,000 glass photographic plates (mostly 20 x 25~cm) that record images of the full sky taken by some 20 telescopes in both hemispheres over the period 1880 - 1985. These provide ˜500-1000 measures of any object brighter than the plate limit (typically B ˜14 - 17) with photometric accuracy from the digital image typically Δm ˜0.10 - 0.15 mag, with the presently developed photometry pipeline and spatially-dependent calibration (using the Hubble Guide Star Catalog) for each plate. We provide an overview of DASCH, the processing, and example light curves that illustrate the power of this unique dataset and resource. Production scanning and serving on-line the entire ˜1 PB database (both images and derived light curves) on spinning disk could be completed within ˜3 - 5 y after funding (for scanner operations and database construction) is obtained.

All Sky Cloud Coverage Monitoring for SONG-China Project

NASA Astrophysics Data System (ADS)

Tian, J. F.; Deng, L. C.; Yan, Z. Z.; Wang, K.; Wu, Y.

2016-05-01

In order to monitor the cloud distributions at Qinghai station, a site selected for SONG (Stellar Observations Network Group)-China node, the design of the proto-type of all sky camera (ASC) applied in Xinglong station is adopted. Both hardware and software improvements have been made in order to be more precise and deliver quantitative measurements. The ARM (Advanced Reduced Instruction Set Computer Machine) MCU (Microcontroller Unit) instead of PC is used to control the upgraded version of ASC. A much higher reliability has been realized in the current scheme. Independent of the positions of the Sun and Moon, the weather conditions are constantly changing, therefore it is difficult to get proper exposure parameters using only the temporal information of the major light sources. A realistic exposure parameters for the ASC can actually be defined using a real-time sky brightness monitor that is also installed at the same site. The night sky brightness value is a very sensitive function of the cloud coverage, and can be accurately measured by the sky quality monitor. We study the correlation between the exposure parameter and night sky brightness value, and give the mathematical relation. The images of the all sky camera are inserted into database directly. All sky quality images are archived in FITS format which can be used for further analysis.

ULTRAVIOLET EXTINCTION AT HIGH GALACTIC LATITUDES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Peek, J. E. G.; Schiminovich, David, E-mail: jegpeek@gmail.com

In order to study the properties and effects of high Galactic latitude dust, we present an analysis of 373,303 galaxies selected from the Galaxy Evolution Explorer All-Sky Survey and Wide-field Infrared Explorer All-Sky Data Release. By examining the variation in aggregate ultraviolet colors and number density of these galaxies, we measure the extinction curve at high latitude. We additionally consider a population of spectroscopically selected galaxies from the Sloan Digital Sky Survey to measure extinction in the optical. We find that dust at high latitude is neither quantitatively nor qualitatively consistent with standard reddening laws. Extinction in the FUV andmore » NUV is {approx}10% and {approx}35% higher than expected, with significant variation across the sky. We find that no single R{sub V} parameter fits both the optical and ultraviolet extinction at high latitude, and that while both show detectable variation across the sky, these variations are not related. We propose that the overall trends we detect likely stem from an increase in very small silicate grains in the interstellar medium.« less

Weak gravitational lensing analysis of Sloan Digital Sky Survey data

NASA Astrophysics Data System (ADS)

Mandelbaum, Rachel

Weak gravitational lensing, the distortion of images of distant galaxies due to gravitational deflection of light by more nearby masses, is a powerful tool that can address a wide variety of problems in astrophysics and cosmology. Observation of weak lensing requires large amounts of data since it can only be measured as an average over millions of galaxy shapes. This thesis focuses on lensing-related science that can be addressed using data from the Sloan Digital Sky Survey (SDSS), an excellent source of high-quality data. First, we discuss technical issues related to observing lensing in the data, with a description of our Reglens pipeline and constraints on systematic errors in current data. This is followed by a comparison of an analytical model known as the halo model (which can be used to relate the observed lensing signal to properties of the lens galaxies) against the lensing signal in N-body simulations. After these preliminaries, we address several very different science questions using our reductions of the SDSS data. The first is the question of intrinsic alignments of galaxies (alignments of galaxies on the sky due to local structure), which may be a contaminant for future lensing surveys that seek to determine the cosmological model to high precision. Second, we use a halo model analysis of the lensing signal to determine the relationship between galaxy luminosity, stellar mass, and halo mass, and to measure satellite fractions, all of which can help distinguish between models of galaxy formation. The third application we consider is methodology for the detection of dark matter halo ellipticity, including a first attempt at detecting it with SDSS lensing data, these results may be used to distinguish between cosmological models and learn more about galaxy intrinsic alignments. Finally, we measure the matter distributions around Luminous Red Galaxies (LRGs), which not only teaches us about the properties of these galaxies, but also gives us information that may constrain the underlying cosmological model. The results of this study are consistent with commonly accepted cosmological models.

A Flight Through the Universe, by the Sloan Digital Sky Survey

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aragon, Miguel; Subbarao, Mark; Szalay, Alex

This animated flight through the universe was made by Miguel Aragon of Johns Hopkins University with Mark Subbarao of the Adler Planetarium and Alex Szalay of Johns Hopkins. There are close to 400,000 galaxies in the animation, with images of the actual galaxies in these positions (or in some cases their near cousins in type) derived from the Sloan Digital Sky Survey (SDSS) Data Release 7. Vast as this slice of the universe seems, its most distant reach is to redshift 0.1, corresponding to roughly 1.3 billion light years from Earth. SDSS Data Release 9 from the Baryon Oscillation Spectroscopicmore » Survey (BOSS), led by Berkeley Lab scientists, includes spectroscopic data for well over half a million galaxies at redshifts up to 0.8 -- roughly 7 billion light years distant -- and over a hundred thousand quasars to redshift 3.0 and beyond.« less

Hypercalibration: A Pan-STARRS1-Based Recalibration of the Sloan Digital Sky Survey Photometry

DOE PAGES

Finkbeiner, Douglas P.; Schlafly, Edward F.; Schlegel, David J.; ...

2016-05-05

In this paper, 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 onmore » photometric deviations co-temporal in SDSS bands. Finally, 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.« less

On the Photometric Calibration of FORS2 and the Sloan Digital Sky Survey

NASA Astrophysics Data System (ADS)

Bramich, D.; Moehler, S.; Coccato, L.; Freudling, W.; Garcia-Dabó, C. E.; Müller, P.; Saviane, I.

2012-09-01

An accurate absolute calibration of photometric data to place them on a standard magnitude scale is very important for many science goals. Absolute calibration requires the observation of photometric standard stars and analysis of the observations with an appropriate photometric model including all relevant effects. In the FORS Absolute Photometry (FAP) project, we have developed a standard star observing strategy and modelling procedure that enables calibration of science target photometry to better than 3% accuracy on photometrically stable nights given sufficient signal-to-noise. In the application of this photometric modelling to large photometric databases, we have investigated the Sloan Digital Sky Survey (SDSS) and found systematic trends in the published photometric data. The amplitudes of these trends are similar to the reported typical precision (˜1% and ˜2%) of the SDSS photometry in the griz- and u-bands, respectively.

Photometric Assessment of Night Sky Quality over Chaco Culture National Historical Park

NASA Astrophysics Data System (ADS)

Hung, Li-Wei; Duriscoe, Dan M.; White, Jeremy M.; Meadows, Bob; Anderson, Sharolyn J.

2018-06-01

The US National Park Service (NPS) characterizes night sky conditions over Chaco Culture National Historical Park using measurements in the park and satellite data. The park is located near the geographic center of the San Juan Basin of northwestern New Mexico and the adjacent Four Corners state. In the park, we capture a series of night sky images in V-band using our mobile camera system on nine nights from 2001 to 2016 at four sites. We perform absolute photometric calibration and determine the image placement to obtain multiple 45-million-pixel mosaic images of the entire night sky. We also model the regional night sky conditions in and around the park based on 2016 VIIRS satellite data. The average zenith brightness is 21.5 mag/arcsec2, and the whole sky is only ~16% brighter than the natural conditions. The faintest stars visible to naked eyes have magnitude of approximately 7.0, reaching the sensitivity limit of human eyes. The main impacts to Chaco’s night sky quality are the light domes from Albuquerque, Rio Rancho, Farmington, Bloomfield, Gallup, Santa Fe, Grants, and Crown Point. A few of these light domes exceed the natural brightness of the Milky Way. Additionally, glare sources from oil and gas development sites are visible along the north and east horizons. Overall, the night sky quality at Chaco Culture National Historical Park is very good. The park preserves to a large extent the natural illumination cycles, providing a refuge for crepuscular and nocturnal species. During clear and dark nights, visitors have an opportunity to see the Milky Way from nearly horizon to horizon, complete constellations, and faint astronomical objects and natural sources of light such as the Andromeda Galaxy, zodiacal light, and airglow.

BAO Plate Archive Project

NASA Astrophysics Data System (ADS)

Mickaelian, A. M.; Gigoyan, K. S.; Gyulzadyan, M. V.; Paronyan, G. M.; Abrahamyan, H. V.; Andreasyan, H. R.; Azatyan, N. M.; Kostandyan, G. R.; Samsonyan, A. L.; Mikayelyan, G. A.; Farmanyan, S. V.; Harutyunyan, V. L.

2017-12-01

We present the Byurakan Astrophysical Observatory (BAO) Plate Archive Project that is aimed at digitization, extraction and analysis of archival data and building an electronic database and interactive sky map. BAO Plate Archive consists of 37,500 photographic plates and films, obtained with 2.6m telescope, 1m and 0.5m Schmidt telescopes and other smaller ones during 1947-1991. The famous Markarian Survey (or the First Byurakan Survey, FBS) 2000 plates were digitized in 2002-2005 and the Digitized FBS (DFBS, www.aras.am/Dfbs/dfbs.html) was created. New science projects have been conducted based on this low-dispersion spectroscopic material. Several other smaller digitization projects have been carried out as well, such as part of Second Byurakan Survey (SBS) plates, photographic chain plates in Coma, where the blazar ON 231 is located and 2.6m film spectra of FBS Blue Stellar Objects. However, most of the plates and films are not digitized. In 2015, we have started a project on the whole BAO Plate Archive digitization, creation of electronic database and its scientific usage. Armenian Virtual Observatory (ArVO, www.aras.am/Arvo/arvo.htm) database will accommodate all new data. The project runs in collaboration with the Armenian Institute of Informatics and Automation Problems (IIAP) and will continues during 4 years in 2015-2018. The final result will be an Electronic Database and online Interactive Sky map to be used for further research projects. ArVO will provide all standards and tools for efficient usage of the scientific output and its integration in international databases.

Commentary: Learning About the Sky Through Simulations. Chapter 34

NASA Technical Reports Server (NTRS)

Way, Michael J.

2012-01-01

The Large Synoptic Survey Telescope (LSST) simulator being built by Andy Connolly and collaborators is an impressive undertaking and should make working with LSST in the beginning stages far more easy than it was initially with the Sloan Digital Sky Survey (SDSS). However, I would like to focus on an equally important problem that has not yet been discussed here, but in the coming years the community will need to address-can we deal with the flood of data from LSST and will we need to rethink the way we work?

Advances in a study of sky quality for astronomical observations in Colombia

NASA Astrophysics Data System (ADS)

González-Díaz, D.; Pinzón, G.

2015-10-01

The aim of this study is to determine the sky quality in Colombia for astronomical observations in the optic. About 10,000 images in infrared (6.7 mu m and 10.7 mu m) were analyzed from the GOES meteorological satellites in three night times taken during a period of five years (2008 to 2014). A novel methodology was followed to determine how clear or covered was the sky in a given image. Meteorological data also were used from the weather stations network of the national meteorological institute, IDEAM. A correlation between threshold temperature and altitude was found for a historical data series of about 30 years. The results of the average percentage of nights with clear skies per year or clear sky fraction (CSF) were validated with the reports on the number of hours of astronomical observation from the logbooks of Llano del Hato Observatory in Merida-Venezuela, obtaining a cumulative percentage difference during the five years less than 10%. Annual cloud covering was computed over the whole country and it was classified the nights as clear or usable based on the definition of a quality factor.

Design of a Teacher Professional Development Program for International Collaborative Astronomy Research in Chile

NASA Astrophysics Data System (ADS)

Pompea, S. M.; Seguel, J.; Sparks, R.; Opazo, L.; Walker, C. E.

2011-12-01

We have designed (but not yet implemented) a program where five US teachers will team with five Chilean teachers to conduct high-quality astronomical research in Chile that can be brought back to their classrooms and shared with their students. This project will introduce US teachers to four research projects at the Observatorio Cruz del Sur, one the largest municipal observatories in South America. The program would operate over the course of a year or more, with a month of observing and conducting research in Chile. The observatory is located in the small town of Combarbalá (Limari Province, IV Región de Coquimbo) in a region rich in archeological, historical, and cultural heritage. Teachers will use high-sensitivity digital detectors to take data through telescopes and with cameras as part of four research projects- light pollution research, digital photography of dark large areas of the sky using wide angle cameras, asteroid photometry, and exoplanet photometric studies. The project partners the National Optical Astronomy Observatory (Tucson, Arizona and La Serena, Chile), the Municipality of the town of Combarbalá, the National Observatory of Chile/University of Chile, and REUNA, an internet communication alliance that serves Chilean universities and observatories. Since the US teachers will have their astronomy classes running while they are in Chile, the teachers will be communicating with their classes on a regular basis. The teachers will also be providing long-term access to southern sky data for other teachers and students in the US while establishing the basis for long-term collaborative research. We expect the program to establish long-term international research collaborations among US and Chilean teachers and students.

North America Nebula in Different Lights

NASA Image and Video Library

2011-02-10

This view of the North America nebula combines both visible and infrared light observations, taken by the Digitized Sky Survey and NASA Spitzer Space Telescope. Clusters of young stars about one million years old can be found throughout the image.

VizieR Online Data Catalog: Carbon-enhanced metal-poor stars sample (Caffau+, 2018)

NASA Astrophysics Data System (ADS)

Caffau, E.; Gallagher, A. J.; Bonifacio, P.; Spite, M.; Duffau, S.; Spite, F.; Monaco, L.; Sbordone, L.

2018-06-01

We selected a sample of turn-off stars from the Sloan Digital Sky Survey (SDSS York et al. 2000AJ....120.1579Y; Yanny et al. 2009, Cat. J/AJ/137/4377) that were bright enough (g<17) to allow us to secure a reasonable spectrum quality in a single observing block of 1h. The FORS spectra have been observed in service mode during the ESO Programme 099.D-0791, between 01/04/2017 and 16/08/2017. The GMOS spectra were acquired in service mode on the nights of 21/07/2017 and 25/07/2017. Table 1 lists the stars we examined here, along with their coordinates, g-mag, and metallicities derived from Fe abundances computed using SDSS and FORS/GMOS spectra. (2 data files).

From Sky to Archive: Long Term Management of Sky Survey Data

NASA Astrophysics Data System (ADS)

Darch, Peter T.; Sands, Ashley E.; Borgman, Christine; Golshan, Milena S.; Traweek, Sharon

2017-01-01

Sky survey data may remain scientifically valuable long beyond the end of a survey’s operational period, both for continuing inquiry and for calibrating and testing instruments for subsequent generations of surveys. Astronomy infrastructure has many stakeholders, including those concerned with data management. Research libraries are increasingly partnering with scholars to sustain access to data.The Sloan Digital Sky Survey (SDSS) was among the first major scientific projects to partner with libraries in this way, embarking on a data transfer process with two university libraries. We report on a qualitative case study of this process.Ideally, long-term sustainability of sky survey data would be a key part of planning and construction, but rarely does this occur. Teams are under pressure to deliver a project on time and on budget that produces high-quality data during its operational period, leaving few resources available to plan long-term data management. The difficulty of planning is further compounded by the complexity of predicting circumstances and needs of the astronomy community in future decades. SDSS team members regarded libraries, long-lived institutions concerned with access to scholarship, as a potential solution to long-term data sustainability.As the SDSS data transfer was the first of this scale attempted - 160 TB of data - astronomers and library staff were faced with scoping the range of activities involved. They spent two years planning this five-year process. While successful overall as demonstration projects, the libraries encountered many obstacles. We found all parties experienced difficulty in articulating their notions of “scientific data,” “archiving,” “serving,” and “providing access” to the datasets. Activities and interpretations of the data transfer process varied by institutional motivations for participation and by available infrastructure. We conclude several, rather than a single, “library solutions” for long-term data management should be considered. Life cycle models popular in the library community are insufficient to conceptualize data management at this scale. We also identify institutional and policy challenges for curating large scientific datasets.

Atmospheric ozone and colors of the Antarctic twilight sky.

PubMed

Lee, Raymond L; Meyer, Wolfgang; Hoeppe, Götz

2011-10-01

Zenith skylight is often distinctly blue during clear civil twilights, and much of this color is due to preferential absorption at longer wavelengths by ozone's Chappuis bands. Because stratospheric ozone is greatly depleted in the austral spring, such decreases could plausibly make Antarctic twilight colors less blue then, including at the zenith. So for several months in 2005, we took digital images of twilight zenith and antisolar skies at Antarctica's Georg von Neumayer Station. Our colorimetric analysis of these images shows only weak correlations between ozone concentration and twilight colors. We also used a spectroradiometer at a midlatitude site to measure zenith twilight spectra and colors. At both locations, spectral extinction by aerosols seems as important as ozone absorption in explaining colors seen throughout the twilight sky.

SED16 autonomous star tracker night sky testing

NASA Astrophysics Data System (ADS)

Foisneau, Thierry; Piriou, Véronique; Perrimon, Nicolas; Jacob, Philippe; Blarre, Ludovic; Vilaire, Didier

2017-11-01

The SED16 is an autonomous multi-missions star tracker which delivers three axis satellite attitude in an inertial reference frame and the satellite angular velocity with no prior information. The qualification process of this star sensor includes five validation steps using optical star simulator, digitized image simulator and a night sky tests setup. The night sky testing was the final step of the qualification process during which all the functions of the star tracker were used in almost nominal conditions : Autonomous Acquisition of the attitude, Autonomous Tracking of ten stars. These tests were performed in Calern in the premises of the OCA (Observatoire de la Cote d'Azur). The test set-up and the test results are described after a brief review of the sensor main characteristics and qualification process.

Flying across Galaxy Clusters with Google Earth: additional imagery from SDSS co-added data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hao, Jiangang; Annis, James; /Fermilab

2010-10-01

Galaxy clusters are spectacular. We provide a Google Earth compatible imagery for the deep co-added images from the Sloan Digital Sky Survey and make it a tool for examing galaxy clusters. Google Earth (in sky mode) provides a highly interactive environment for visualizing the sky. By encoding the galaxy cluster information into a kml/kmz file, one can use Google Earth as a tool for examining galaxy clusters and fly across them freely. However, the resolution of the images provided by Google Earth is not very high. This is partially because the major imagery google earth used is from Sloan Digitalmore » Sky Survey (SDSS) (SDSS collaboration 2000) and the resolutions have been reduced to speed up the web transferring. To have higher resolution images, you need to add your own images in a way that Google Earth can understand. The SDSS co-added data are the co-addition of {approx}100 scans of images from SDSS stripe 82 (Annis et al. 2010). It provides the deepest images based on SDSS and reach as deep as about redshift 1.0. Based on the co-added images, we created color images in a way as described by Lupton et al. (2004) and convert the color images to Google Earth compatible images using wcs2kml (Brewer et al. 2007). The images are stored at a public server at Fermi National Accelerator Laboratory and can be accessed by the public. To view those images in Google Earth, you need to download a kmz file, which contains the links to the color images, and then open the kmz file with your Google Earth. To meet different needs for resolutions, we provide three kmz files corresponding to low, medium and high resolution images. We recommend the high resolution one as long as you have a broadband Internet connection, though you should choose to download any of them, depending on your own needs and Internet speed. After you open the downloaded kmz file with Google Earth (in sky mode), it takes about 5 minutes (depending on your Internet connection and the resolution of images you want) to get some initial images loaded. Then, additional images corresponding to the region you are browsing will be loaded automatically. So far, you have access to all the co-added images. But you still do not have the galaxy cluster position information to look at. In order to see the galaxy clusters, you need to download another kmz file that tell Google Earth where to find the galaxy clusters in the co-added data region. We provide a kmz file for a few galaxy clusters in the stripe 82 region and you can download and open it with Google Earth. In the SDSS co-added region (stripe 82 region), the imagery from Google Earth itself is from the Digitized Sky Survey (2007), which is in very poor quality. In Figure1 and Figure2, we show screenshots of a cluster with and without the new co-added imagery in Google Earth. Much more details have been revealed with the deep images.« less

Dark Skies Awareness Programs for the U.S. International Year of Astronomy

NASA Astrophysics Data System (ADS)

Walker, Constance E.; U. S. IYA Dark Skies Working Group

2009-01-01

The loss of a dark night sky as a natural resource is a growing concern. It impacts not only astronomical research, but also our ecology, health, safety, economics and energy conservation. For this reason, "Dark Skies are a Universal Resource” is one of seven primary themes of the U.S. International Year of Astronomy program in 2009. Its goal is to raise public awareness of the impact of artificial lighting on local environments by getting people involved in a variety of dark skies-related programs. To reach this goal, activities have been developed that: 1) Teach about dark skies using new technology (e.g., an activity-based planetarium show on DVD, podcasting, social networking, Second Life) 2) Provide thematic events on light pollution at star parties and observatory open houses (Dark Skies Discovery Sites, Astronomy Nights in the (National) Parks, Sidewalk Astronomy Nights) 3) Organize an event in the arts (e.g., a photography contest) 4) Involve citizen-scientists in unaided-eye and digital-meter star counting programs, as well as RFI monitoring (e.g., GLOBE at Night and Quiet Skies) and 5) Raise awareness about the link between light pollution and public health, economic issues, ecological consequences, energy conservation, safety and security (e.g., the Dark Skies Toolkit, Good Neighbor Lighting, Earth Hour, National Dark Skies Week, traveling exhibits and a 6-minute video tutorial). To deliver these programs, strategic networks have been established with astronomy clubs (ASP's Night Sky Network's astronomy clubs and the Astronomical League), science and nature centers (Astronomy from the Ground Up and the Association of Science and Technology), educational programs (Project ASTRO and GLOBE) and the International Dark-sky Association. The poster will describe the "know-how” and the means for people to become community advocates in promoting Dark Skies programs as public events at their home institutions. For more information, visit http://astronomy2009.us/darkskies/.

Methods in Astronomical Image Processing

NASA Astrophysics Data System (ADS)

Jörsäter, S.

A Brief Introductory Note History of Astronomical Imaging Astronomical Image Data Images in Various Formats Digitized Image Data Digital Image Data Philosophy of Astronomical Image Processing Properties of Digital Astronomical Images Human Image Processing Astronomical vs. Computer Science Image Processing Basic Tools of Astronomical Image Processing Display Applications Calibration of Intensity Scales Calibration of Length Scales Image Re-shaping Feature Enhancement Noise Suppression Noise and Error Analysis Image Processing Packages: Design of AIPS and MIDAS AIPS MIDAS Reduction of CCD Data Bias Subtraction Clipping Preflash Subtraction Dark Subtraction Flat Fielding Sky Subtraction Extinction Correction Deconvolution Methods Rebinning/Combining Summary and Prospects for the Future

A catalogue of clusters of galaxies identified from all sky surveys of 2MASS, WISE, and SuperCOSMOS

NASA Astrophysics Data System (ADS)

Wen, Z. L.; Han, J. L.; Yang, F.

2018-03-01

We identify 47 600 clusters of galaxies from photometric data of Two Micron All Sky Survey (2MASS), Wide-field Infrared Survey Explorer (WISE), and SuperCOSMOS, among which 26 125 clusters are recognized for the first time and mostly in the sky outside the Sloan Digital Sky Survey (SDSS) area. About 90 per cent of massive clusters of M500 > 3 × 1014 M⊙ in the redshift range of 0.025 < z < 0.3 have been detected from such survey data, and the detection rate drops down to 50 per cent for clusters with a mass of M500 ˜ 1 × 1014 M⊙. Monte Carlo simulations show that the false detection rate for the whole cluster sample is less than 5 per cent. By cross-matching with ROSAT and XMM-Newton sources, we get 779 new X-ray cluster candidates which have X-ray counterparts within a projected offset of 0.2 Mpc.

Stereoscopic determination of all-sky altitude map of aurora using two ground-based Nikon DSLR cameras

NASA Astrophysics Data System (ADS)

Kataoka, R.; Miyoshi, Y.; Shigematsu, K.; Hampton, D.; Mori, Y.; Kubo, T.; Yamashita, A.; Tanaka, M.; Takahei, T.; Nakai, T.; Miyahara, H.; Shiokawa, K.

2013-09-01

A new stereoscopic measurement technique is developed to obtain an all-sky altitude map of aurora using two ground-based digital single-lens reflex (DSLR) cameras. Two identical full-color all-sky cameras were set with an 8 km separation across the Chatanika area in Alaska (Poker Flat Research Range and Aurora Borealis Lodge) to find localized emission height with the maximum correlation of the apparent patterns in the localized pixels applying a method of the geographical coordinate transform. It is found that a typical ray structure of discrete aurora shows the broad altitude distribution above 100 km, while a typical patchy structure of pulsating aurora shows the narrow altitude distribution of less than 100 km. Because of its portability and low cost of the DSLR camera systems, the new technique may open a unique opportunity not only for scientists but also for night-sky photographers to complementarily attend the aurora science to potentially form a dense observation network.

Karhunen-Loeve Estimation of the Power Spectrum Parameters from the Angular Distribution of Galaxies in Early Sloan Digital Sky Survey Data

NASA Technical Reports Server (NTRS)

Szalay, Alexander S.; Jain, Bhuvnesh; Matsubara, Takahiko; Scranton, Ryan; Vogeley, Michael S.; Connolly, Andrew; Dodelson, Scott; Eisenstein, Daniel; Frieman, Joshua A.; Gunn, James E.

2003-01-01

We present measurements of parameters of the three-dimensional power spectrum of galaxy clustering from 222 square degrees of early imaging data in the Sloan Digital Sky Survey (SDSS). The projected galaxy distribution on the sky is expanded over a set of Karhunen-Loeve (KL) eigenfunctions, which optimize the signal-to-noise ratio in our analysis. A maximum likelihood analysis is used to estimate parameters that set the shape and amplitude of the three-dimensional power spectrum of galaxies in the SDSS magnitude-limited sample with r* less than 21. Our best estimates are gamma = 0.188 +/- 0.04 and sigma(sub 8L) = 0.915 +/- 0.06 (statistical errors only), for a flat universe with a cosmological constant. We demonstrate that our measurements contain signal from scales at or beyond the peak of the three-dimensional power spectrum. We discuss how the results scale with systematic uncertainties, like the radial selection function. We find that the central values satisfy the analytically estimated scaling relation. We have also explored the effects of evolutionary corrections, various truncations of the KL basis, seeing, sample size, and limiting magnitude. We find that the impact of most of these uncertainties stay within the 2 sigma uncertainties of our fiducial result.

The Quality Lighting Teaching Kit: Educating the Public about the Dark Side of IYL2015

NASA Astrophysics Data System (ADS)

Walker, Constance Elaine; Pompea, Stephen M.; Levy, Rebecca

2015-08-01

The UN-sanctioned International Year of Light in 2015 (IYL2015) is providing an opportunity to increase public awareness of dark skies preservation, quality lighting and energy conservation. The Education and Public Outreach (EPO) group at the U.S. National Optical Astronomy Observatory (NOAO) has received a grant through the IAU to produce official “Quality Lighting Teaching Kits” for the IYL2015 cornerstone theme, “Cosmic Light”. These kits will emphasize the use of proper optical design in achieving quality lighting that promotes both energy efficiency and energy conservation of an endangered natural resource: our dark skies. Poor quality lighting not only impedes astronomy research, but creates safety issues, affects human circadian sensitivities, disrupts ecosystems, and wastes billions of dollars/year in energy consumption and carbon emissions.The concepts and practices of “quality lighting” will be explored through problem-based learning (e.g., engineering design), hands-on/minds-on activities, demonstrations, and formative and summative assessment probes. The impact of the kits will be amplified by providing professional development using tutorial videos created at NOAO and conducting question and answer sessions via Google+ Hangouts for program participants. The Quality Lighting Teaching Kit will leverage ten years of work by NOAO’s EPO team in developing programs on lighting and optics education (e.g., the NSF-funded “Hands on Optics”, IAU “Dark Skies Africa” and Arizona Public Service Foundation’s “Dark Skies Yuma” programs).NOAO’s partners are the International Society for Optics and Photonics (SPIE), International Commission on Illumination (CIE), International Dark-Sky Association (IDA), and IAU Office of Astronomy for Development, with sponsorship from the IAU and The Optical Society (OSA). Along with astronomy education centers (NUCLIO and Universe Awareness), the networks will disseminate kits to formal and informal audiences worldwide. The impact sought is a change in knowledge, attitude, and behavior in each community by learning how to light responsibly, improving the quality of life in “illuminating” ways.

Anomalous Arms

NASA Image and Video Library

2007-12-18

This composite image is of spiral galaxy M106 NGC 4258; optical data from the Digitized Sky Survey is yellow, radio data from the Very Large Array is purple, X-ray data from Chandra is blue, and infrared data from the Spitzer Space Telescope is red.

Teach Astronomy: An Online Resource for Introductory Astronomy Courses and Informal Learners

NASA Astrophysics Data System (ADS)

Austin, Carmen; Impey, C. D.; Hardegree-Ullman, K.; Patikkal, A.; Ganesan, N.

2013-01-01

Teach Astronomy (www.teachastronomy.com) is a new, free online resource—a teaching tool for non-science major astronomy courses and a reference guide for lifelong learners interested in the subject. Digital content available includes: a comprehensive introductory astronomy textbook by Chris Impey, Wikipedia astronomy articles, images from Astronomy Picture of the Day archives and AstroPix database, two to three minute topical video clips by Chris Impey, podcasts from 365 Days of Astronomy archives, and an RSS feed of astronomy news from Science Daily. Teach Astronomy features an original technology called the Wikimap to cluster, display, and navigate site search results. Motivation behind the development of Teach Astronomy includes steep increases in textbook prices, the rapid adoption by students and the public of digital resources, and the modern capabilities of digital technology. Recent additions to Teach Astronomy include: AstroPix images—from some of the most advanced observatories and complete with metadata, mobile device functionality, links to WikiSky where users can see the location of astronomical objects in the sky, and end of chapter textbook review questions. Next in line for development are assignments for classroom use. We present suggestions for utilizing the rich content and features of the web site.

DESCQA: Synthetic Sky Catalog Validation Framework

NASA Astrophysics Data System (ADS)

Mao, Yao-Yuan; Uram, Thomas D.; Zhou, Rongpu; Kovacs, Eve; Ricker, Paul M.; Kalmbach, J. Bryce; Padilla, Nelson; Lanusse, François; Zu, Ying; Tenneti, Ananth; Vikraman, Vinu; DeRose, Joseph

2018-04-01

The DESCQA framework provides rigorous validation protocols for assessing the quality of high-quality simulated sky catalogs in a straightforward and comprehensive way. DESCQA enables the inspection, validation, and comparison of an inhomogeneous set of synthetic catalogs via the provision of a common interface within an automated framework. An interactive web interface is also available at portal.nersc.gov/project/lsst/descqa.

An Automatic System for Global Monitoring of ELF and VLF Radio Noise Phenomena.

DTIC Science & Technology

1985-06-01

second low-jitter synchronization signal is also provided for precise triggering of analog-to- digital conversion samples. Both the clock and the...building in 1985 are two riometers (30 MHz and 51.4 MHz), a 3-axis fluxgate magnetometer , a 3-axis micropulsation magnetometer , an all-sky camera, and...of these filters 1s continuously sampled by a computerized recording system, and statistical averages are computed on-site and recorded on digital tape

BlueSky Cloud - rapid infrastructure capacity using Amazon's Cloud for wildfire emergency response

NASA Astrophysics Data System (ADS)

Haderman, M.; Larkin, N. K.; Beach, M.; Cavallaro, A. M.; Stilley, J. C.; DeWinter, J. L.; Craig, K. J.; Raffuse, S. M.

2013-12-01

During peak fire season in the United States, many large wildfires often burn simultaneously across the country. Smoke from these fires can produce air quality emergencies. It is vital that incident commanders, air quality agencies, and public health officials have smoke impact information at their fingertips for evaluating where fires and smoke are and where the smoke will go next. To address the need for this kind of information, the U.S. Forest Service AirFire Team created the BlueSky Framework, a modeling system that predicts concentrations of particle pollution from wildfires. During emergency response, decision makers use BlueSky predictions to make public outreach and evacuation decisions. The models used in BlueSky predictions are computationally intensive, and the peak fire season requires significantly more computer resources than off-peak times. Purchasing enough hardware to run the number of BlueSky Framework runs that are needed during fire season is expensive and leaves idle servers running the majority of the year. The AirFire Team and STI developed BlueSky Cloud to take advantage of Amazon's virtual servers hosted in the cloud. With BlueSky Cloud, as demand increases and decreases, servers can be easily spun up and spun down at a minimal cost. Moving standard BlueSky Framework runs into the Amazon Cloud made it possible for the AirFire Team to rapidly increase the number of BlueSky Framework instances that could be run simultaneously without the costs associated with purchasing and managing servers. In this presentation, we provide an overview of the features of BlueSky Cloud, describe how the system uses Amazon Cloud, and discuss the costs and benefits of moving from privately hosted servers to a cloud-based infrastructure.

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

DTIC Science & Technology

2014-03-20

reserved. Printed in the U.S.A. CHARACTERIZATION OF THE PRAESEPE STAR CLUSTER BY PHOTOMETRY AND PROPER MOTIONS WITH 2MASS , PPMXL, AND Pan-STARRS P. F. Wang1... 2MASS ) and the Sloan Digital Sky Survey (SDSS) data, covering a sky area of 100 deg2, Adams et al. (2002) extended the lower main sequence to 0.1M, and...incompleteness is caused by the detection limits of USNO-B1 and 2MASS . Recently, Khalaj & Baumgardt (2013) used SDSS and PPMXL data to characterize

Eye on the Sky

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johnson, Spencer

Every night in a remote clearing called Fenton Hill high in the Jemez Mountains of central New Mexico, a bank of robotically controlled telescopes tilt their lenses to the sky for another round of observation through digital imaging. Los Alamos National Laboratory’s Thinking Telescopes project is watching for celestial transients including high-power cosmic flashes called blazars, and like all science, it can be messy work. But for a graduate student at the Lab taking a year’s break between master’s and Ph.D. studies, working with these state-of-the-art autonomous telescopes that can make fundamental discoveries feels light years beyond the classroom.

Detection of Galaxy Cluster Motions with the Kinematic Sunyaev-Zel'dovich Effect

NASA Technical Reports Server (NTRS)

Hand, Nick; Addison, Graeme E.; Aubourg, Eric; Battaglia, Nick; Battistelli, Elia S.; Bizyaev, Dmitry; Bond, J. Richard; Brewington, Howard; Brinkmann, Jon; Brown, Benjamin R.;

There Are (super)Giants in the Sky: Searching for Misidentified Massive Stars in Algorithmically-Selected Quasar Catalogs

NASA Astrophysics Data System (ADS)

Dorn-Wallenstein, Trevor Z.; Levesque, Emily

2017-11-01

Thanks to incredible advances in instrumentation, surveys like the Sloan Digital Sky Survey have been able to find and catalog billions of objects, ranging from local M dwarfs to distant quasars. Machine learning algorithms have greatly aided in the effort to classify these objects; however, there are regimes where these algorithms fail, where interesting oddities may be found. We present here an X-ray bright quasar misidentified as a red supergiant/X-ray binary, and a subsequent search of the SDSS quasar catalog for X-ray bright stars misidentified as quasars.

Computer analysis of digital sky surveys using citizen science and manual classification

NASA Astrophysics Data System (ADS)

Kuminski, Evan; Shamir, Lior

2015-01-01

As current and future digital sky surveys such as SDSS, LSST, DES, Pan-STARRS and Gaia create increasingly massive databases containing millions of galaxies, there is a growing need to be able to efficiently analyze these data. An effective way to do this is through manual analysis, however, this may be insufficient considering the extremely vast pipelines of astronomical images generated by the present and future surveys. Some efforts have been made to use citizen science to classify galaxies by their morphology on a larger scale than individual or small groups of scientists can. While these citizen science efforts such as Zooniverse have helped obtain reasonably accurate morphological information about large numbers of galaxies, they cannot scale to provide complete analysis of billions of galaxy images that will be collected by future ventures such as LSST. Since current forms of manual classification cannot scale to the masses of data collected by digital sky surveys, it is clear that in order to keep up with the growing databases some form of automation of the data analysis will be required, and will work either independently or in combination with human analysis such as citizen science. Here we describe a computer vision method that can automatically analyze galaxy images and deduce galaxy morphology. Experiments using Galaxy Zoo 2 data show that the performance of the method increases as the degree of agreement between the citizen scientists gets higher, providing a cleaner dataset. For several morphological features, such as the spirality of the galaxy, the algorithm agreed with the citizen scientists on around 95% of the samples. However, the method failed to analyze some of the morphological features such as the number of spiral arms, and provided accuracy of just ~36%.

A billion stars, a few million galaxies

NASA Astrophysics Data System (ADS)

Humphreys, Roberta M.; Thurmes, Peter M.

1994-05-01

The creation of an all-sky computerized astronomical catalog is discussed. The data source for the catalog was the first National Geographic Society-Palomar Observatory Sky Survey (POSS 1). Most of the plates produced in POSS 1 with the Oschin 48-inch Schmidt telescope were recently scanned by a team of astronomers using an automated plate scanner (APS) which is a high-speed laser scanner designed specifically to digitized information on astronomical photographs. To access the cataloged information easily, a specialized database program called StarBase was written. The expected size of the complete database (the catalog of objects plus the pixel data for the detected images) is 400 gigabytes. Scanning of 644 pairs of blue and red plates, covering the entire sky except for the crowded region within 20 deg of the galactic plane, has been completed. been completed.

Digital Earth Watch: Investigating the World with Digital Cameras

NASA Astrophysics Data System (ADS)

Gould, A. D.; Schloss, A. L.; Beaudry, J.; Pickle, J.

2015-12-01

Every digital camera including the smart phone camera can be a scientific tool. Pictures contain millions of color intensity measurements organized spatially allowing us to measure properties of objects in the images. This presentation will demonstrate how digital pictures can be used for a variety of studies with a special emphasis on using repeat digital photographs to study change-over-time in outdoor settings with a Picture Post. Demonstrations will include using inexpensive color filters to take pictures that enhance features in images such as unhealthy leaves on plants, or clouds in the sky. Software available at no cost from the Digital Earth Watch (DEW) website that lets students explore light, color and pixels, manipulate color in images and make measurements, will be demonstrated. DEW and Picture Post were developed with support from NASA. Please visit our websites: DEW: http://dew.globalsystemsscience.orgPicture Post: http://picturepost.unh.edu

Discovery of three strongly lensed quasars in the Sloan Digital Sky Survey

NASA Astrophysics Data System (ADS)

Williams, P. R.; Agnello, A.; Treu, T.; Abramson, L. E.; Anguita, T.; Apostolovski, Y.; Chen, G. C.-F.; Fassnacht, C. D.; Hsueh, J. W.; Lemaux, B. C.; Motta, V.; Oldham, L.; Rojas, K.; Rusu, C. E.; Shajib, A. J.; Wang, X.

2018-06-01

We present the discovery of three quasar lenses in the Sloan Digital Sky Survey, selected using two novel photometry-based selection techniques. The J0941+0518 system, with two point sources separated by 5.46 arcsec on either side of a galaxy, has source and lens redshifts 1.54 and 0.343. Images of J2257+2349 show two point sources separated by 1.67 arcsec on either side of an E/S0 galaxy. The extracted spectra show two images of the same quasar at zs = 2.10. SDSS J1640+1045 has two quasar spectra at zs = 1.70 and fits to the SDSS and Pan-STARRS images confirm the presence of a galaxy between the two point sources. We observed 56 photometrically selected lens candidates in this follow-up campaign, confirming three new lenses, re-discovering one known lens, and ruling out 36 candidates, with 16 still inconclusive. This initial campaign demonstrates the power of purely photometric selection techniques in finding lensed quasars.

A SURVEY OF CN AND CH VARIATIONS IN GALACTIC GLOBULAR CLUSTERS FROM SLOAN DIGITAL SKY SURVEY SPECTROSCOPY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smolinski, Jason P.; Beers, Timothy C.; Lee, Young Sun

We present a homogeneous survey of the CN and CH band strengths in eight Galactic globular clusters observed during the course of the Sloan Extension for Galactic Understanding and Exploration sub-survey of the Sloan Digital Sky Survey. We confirm the existence of a bimodal CN distribution among red giant branch (RGB) stars in all of the clusters with metallicity greater than [Fe/H] = -1.7; the lowest metallicity cluster with an observed CN bimodality is M53, with [Fe/H] {approx_equal} -2.1. There is also some evidence for individual CN groups on the subgiant branches of M92, M2, and M13, and on themore » RGBs of M92 and NGC 5053. Finally, we quantify the correlation between overall cluster metallicity and the slope of the CN band strength-luminosity plot as a means of further demonstrating the level of CN enrichment in cluster giants. Our results agree well with previous studies reported in the literature.« less

TWO NEW HALO DEBRIS STREAMS IN THE SLOAN DIGITAL SKY SURVEY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grillmair, C. J., E-mail: carl@ipac.caltech.edu

2014-07-20

Using photometry from Data Release 10 of the northern footprint of the Sloan Digital Sky Survey, we detect two new stellar streams with lengths of between 25° and 50°. The streams, which we designate Hermus and Hyllus, are at distances of between 15 and 23 kpc from the Sun and pass primarily through Hercules and Corona Borealis. Stars in the streams appear to be metal-poor, with [Fe/H] ∼ – 2.3, though we cannot rule out metallicities as high as [Fe/H] = –1.2. While Hermus passes within 1° (in projection) of the globular cluster NGC 6229, a roughly one magnitude difference in distancemore » modulus, combined with no signs of connecting with NGC 6229's Roche lobe, argue against any physical association between the two. Though the two streams almost certainly had different progenitors, similarities in preliminary orbit estimates suggest that those progenitors may themselves have been a product of a single accretion event.« less

A NEAR-INFRARED SPECTROSCOPIC SURVEY OF COOL WHITE DWARFS IN THE SLOAN DIGITAL SKY SURVEY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kilic, Mukremin; Kowalski, Piotr M.; Von Hippel, Ted

2009-07-15

We present near-infrared photometric observations of 15 and spectroscopic observations of 38 cool white dwarfs (WDs). This is the largest near-infrared spectroscopic survey of cool WDs to date. Combining the Sloan Digital Sky Survey photometry and our near-infrared data, we perform a detailed model atmosphere analysis. The spectral energy distributions of our objects are explained fairly well by model atmospheres with temperatures ranging from 6300 K down to 4200 K. Two WDs show significant absorption in the infrared, and are best explained with mixed H/He atmosphere models. Based on the up-to-date model atmosphere calculations by Kowalski and Saumon, we findmore » that the majority of the stars in our sample have hydrogen-rich atmospheres. We do not find any pure helium atmosphere WDs below 5000 K, and we find a trend of increasing hydrogen to helium ratio with decreasing temperature. These findings present an important challenge to understanding the spectral evolution of WDs.« less

VizieR Online Data Catalog: Northern Sky Variability Survey (Wozniak+, 2004)

NASA Astrophysics Data System (ADS)

Wozniak, P. R.; Vestrand, W. T.; Akerlof, C. W.; Balsano, R.; Bloch, J.; Casperson, D.; Fletcher, S.; Gisler, G.; Kehoe, R.; Kinemuchi, K.; Lee, B. C.; Marshall, S.; McGowan, K. E.; McKay, T. A.; Rykoff, E. S.; Smith, D. A.; Szymanski, J.; Wren, J.

2004-11-01

The Northern Sky Variability Survey (NSVS) is a temporal record of the sky over the optical magnitude range from 8 to 15.5. It was conducted in the course of the first-generation Robotic Optical Transient Search Experiment (ROTSE-I) using a robotic system of four comounted unfiltered telephoto lenses equipped with CCD cameras. The survey was conducted from Los Alamos, New Mexico, and primarily covers the entire northern sky. Some data in southern fields between declinations 0{deg} and -38{deg} are also available, although with fewer epochs and noticeably lesser quality. The NSVS contains light curves for approximately 14 million objects. With a 1-yr baseline and typically 100-500 measurements per object, the NSVS is the most extensive record of stellar variability across the bright sky available today. In a median field, bright unsaturated stars attain a point-to-point photometric scatter of ~0.02mag and position errors within 2. At Galactic latitudes |b|<20{deg}, the data quality is limited by severe blending due to the ~14" pixel size. We present basic characteristics of the data set and describe data collection, analysis, and distribution. All NSVS photometric measurements are available for on-line public access from the Sky Database for Objects in Time-Domain (SkyDOT) at Los Alamos National Laboratory. Copies of the full survey photometry may also be requested on tape. (7 data files).

Streaming Multiframe Deconvolutions on GPUs

NASA Astrophysics Data System (ADS)

Lee, M. A.; Budavári, T.

2015-09-01

Atmospheric turbulence distorts all ground-based observations, which is especially detrimental to faint detections. The point spread function (PSF) defining this blur is unknown for each exposure and varies significantly over time, making image analysis difficult. Lucky imaging and traditional co-adding throws away lots of information. We developed blind deconvolution algorithms that can simultaneously obtain robust solutions for the background image and all the PSFs. It is done in a streaming setting, which makes it practical for large number of big images. We implemented a new tool that runs of GPUs and achieves exceptional running times that can scale to the new time-domain surveys. Our code can quickly and effectively recover high-resolution images exceeding the quality of traditional co-adds. We demonstrate the power of the method on the repeated exposures in the Sloan Digital Sky Survey's Stripe 82.

Stability of the nine sky quality meters in the Dutch night sky brightness monitoring network.

PubMed

den Outer, Peter; Lolkema, Dorien; Haaima, Marty; van der Hoff, Rene; Spoelstra, Henk; Schmidt, Wim

2015-04-22

In the context of monitoring abundance of artificial light at night, the year-to-year stability of Sky Quality Meters (SQMs) is investigated by analysing intercalibrations derived from two measurement campaigns that were held in 2011 and 2012. An intercalibration comprises a light sensitivity factor and an offset for each SQM. The campaigns were concerned with monitoring measurements, each lasting one month. Nine SQMs, together forming the Night Sky Brightness Monitoring network (MHN) in The Netherlands, were involved in both campaigns. The stability of the intercalibration of these instruments leads to a year-to-year uncertainty (standard deviation) of 5% in the measured median luminance occurring at the MHN monitoring locations. For the 10-percentiles and 90-percentiles, we find 8% and 4%, respectively. This means that, for urban and industrial areas, changes in the sky brightness larger than 5% become detectable. Rural and nature areas require an 8%-9% change of the median luminance to be detectable. The light sensitivety agrees within 8% for the whole group of SQMs.

Assessing the urban solar energy resource potential of Davao City, Philippines, using LiDAR Digital Surface Model (DSM) and GRASS GIS

NASA Astrophysics Data System (ADS)

Teves, Justine; Sola, Eula Fae; Pintor, Ben Hur; Ang, Ma. Rosario Concepcion

2016-10-01

Solar energy is emerging as one of the top options for renewable energy sources in the Philippines, with largescale solar photovoltaic (PV) farms being built all over the country. Solar energy resource in the urban environment has great potential in making a city self-sustaining, but has not been fully explored for the country. In order to represent its potential, reliable resource assessment should be done. This study aims to assess the available solar energy resource in Davao City, a trade and commerce hub in southern Philippines. The functions of GRASS GIS, specifically the r.sun module, in modelling incoming solar radiation is discussed, along with the use of a one-meter LiDAR Digital Surface Model (DSM) and Linke Turbidity coefficients as inputs. The average Julian day of each month was used to compute the Global Horizontal Irradiation (GHI) values under clear-sky or cloudless conditions. To account for the effects of the clouds in the study area, the clear-sky indices (Kc) were computed using data from solar recording stations of the Bureau of Soils and Water Management (BSWM) found within and around the region. These were multiplied to the modelled clear-sky GHI rasters to get the real-sky GHI. The results show that the city's average GHI potential ranges from 2693.79 Wh/m2 and 4453.13 Wh/m2. Average values are particularly higher around the months of March and April, while lower values are seen in the months of November and January. Areas with higher potential are seen in the southern portion of the city, consistent in built-up areas.

Evaluation of the night sky quality at El Leoncito and LEO++ in Argentina

NASA Astrophysics Data System (ADS)

Aubé, Martin; García, Beatriz; Fortin, Nicolas; Turcotte, Sara; Mancilla, Alexis; Maya, Javier

2015-08-01

Light pollution is a growing concern at many levels, but especially for the astronomical community. Artificial lighting veil celestial objects and disturbs the measurement of night time atmospheric phenomena. This is what motivates our sky brightness measurement experiment in Argentina. Our goal was to determine the quality of two Argentinian observation sites: LEO++ and El Leoncito. Both sites were candidates to host the Cherenkov Telescope Array (CTA). This project consists of an arrangement of many telescopes that can measure high-energy gamma ray emissions via their Cherenkov radiation produced when entering the earth's atmosphere. Even if the two argentinian sites has been excluded from the final CTA site competition, they are still of great interest for other astronomical projects. Especially the El Leoncito site which already hots the CASLEO astronomical complex. In this presentation, we describe the measurement methods used to determine the sky quality. We compared our results with different renowned astronomical sites (Kitt Peak, Arizona, USA, and Mont-Mégantic, Canada). Amongst our results, we found that LEO++ is a high quality site, however there are a lot of aerosols that can interfere with the measurements. El Leoncito shows very low sky brightness levels, which are optimal for low light level detection.

Dark Skies are a Universal Resource: Programs Planned for the International Year of Astronomy

NASA Astrophysics Data System (ADS)

Walker, Constance E.; US IYA Dark Skies Working Group

2008-05-01

The dark night sky is a natural resource that is being lost by much of the world's population. This loss is a growing, serious issue that impacts not only astronomical research, but also human health, ecology, safety, economics and energy conservation. One of the themes of the US Node targeted for the International Year of Astronomy (IYA) is "Dark Skies are a Universal Resource". The goal is to raise public awareness of the impact of artificial lighting on local environments by getting people involved locally in a variety of dark skies-related events. To reach this goal, activities are being developed that: 1) Teach about dark skies using new technology (e.g., an activity-based planetarium show on DVD, podcasting, social networking) 2) Provide thematic events on light pollution at star parties and observatory open houses (Dark Skies Teaching Sites, Astronomy Nights in the (National) Parks, Sidewalk Astronomy Nights) 3) Organize events in the arts (e.g., a photography contest) 4) Involve citizen-scientists in unaided-eye and digital-meter star counting programs (e.g., GLOBE at Night, "How Many Stars?” and the Great World Wide Star Count) and 5) Raise awareness about the link between light pollution and public health, economic issues, ecological consequences, energy conservation, safety and security (e.g., The Great Switch Out, Earth Hour, National Dark Skies Week, traveling exhibits and a 6-minute video tutorial on lighting issues). To deliver these programs, strategic networks have been established with the ASP's Night Sky Network's astronomy clubs, Astronomy from the Ground Up's science and nature centers and the Project and Family ASTRO programs, as well as the International Dark-Sky Association, GLOBE and the Astronomical League, among others. The poster presentation will outline the activities being developed, the plans for funding, implementation, marketing and the connections to the global cornerstone IYA project, "Dark Skies Awareness".

Positions and proper motions of dwarf carbon stars

NASA Technical Reports Server (NTRS)

Deutsch, Eric W.

1994-01-01

Recent-epochs positions and proper motions of nine dwarf carbon star candidates are presented along with finding charts for each object. Measurements are obtained from digitized Palomar Observatory Sky Survey (POSS) and Quik V plate archives at the Space Telescope Science Institute, and from recent CCD images.

Observations of temporal change of nighttime cloud cover from Himawari 8 and ground-based sky camera over Chiba, Japan

NASA Astrophysics Data System (ADS)

Lagrosas, N.; Gacal, G. F. B.; Kuze, H.

2017-12-01

Detection of nighttime cloud from Himawari 8 is implemented using the difference of digital numbers from bands 13 (10.4µm) and 7 (3.9µm). The digital number difference of -1.39x104 can be used as a threshold to separate clouds from clear sky conditions. To look at observations from the ground over Chiba, a digital camera (Canon Powershot A2300) is used to take images of the sky every 5 minutes at an exposure time of 5s at the Center for Environmental Remote Sensing, Chiba University. From these images, cloud cover values are obtained using threshold algorithm (Gacal, et al, 2016). Ten minute nighttime cloud cover values from these two datasets are compared and analyzed from 29 May to 05 June 2017 (20:00-03:00 JST). When compared with lidar data, the camera can detect thick high level clouds up to 10km. The results show that during clear sky conditions (02-03 June), both camera and satellite cloud cover values show 0% cloud cover. During cloudy conditions (05-06 June), the camera shows almost 100% cloud cover while satellite cloud cover values range from 60 to 100%. These low values can be attributed to the presence of low-level thin clouds ( 2km above the ground) as observed from National Institute for Environmental Studies lidar located inside Chiba University. This difference of cloud cover values shows that the camera can produce accurate cloud cover values of low level clouds that are sometimes not detected by satellites. The opposite occurs when high level clouds are present (01-02 June). Derived satellite cloud cover shows almost 100% during the whole night while ground-based camera shows cloud cover values that range from 10 to 100% during the same time interval. The fluctuating values can be attributed to the presence of thin clouds located at around 6km from the ground and the presence of low level clouds ( 1km). Since the camera relies on the reflected city lights, it is possible that the high level thin clouds are not observed by the camera but is observed by the satellite. Also, this condition constitutes layers of clouds that are not observed by each camera. The results of this study show that one instrument can be used to correct each other to provide better cloud cover values. These corrections is dependent on the height and thickness of the clouds. No correction is necessary when the sky is clear.

Angle of sky light polarization derived from digital images of the sky under various conditions.

PubMed

Zhang, Wenjing; Cao, Yu; Zhang, Xuanzhe; Yang, Yi; Ning, Yu

2017-01-20

Skylight polarization is used for navigation by some birds and insects. Skylight polarization also has potential for human navigation applications. Its advantages include relative immunity from interference and the absence of error accumulation over time. However, there are presently few examples of practical applications for polarization navigation technology. The main reason is its weak robustness during cloudy weather conditions. In this paper, the real-time measurement of the sky light polarization pattern across the sky has been achieved with a wide field of view camera. The images were processed under a new reference coordinate system to clearly display the symmetrical distribution of angle of polarization with respect to the solar meridian. A new algorithm for the extraction of the image axis of symmetry is proposed, in which the real-time azimuth angle between the camera and the solar meridian is accurately calculated. Our experimental results under different weather conditions show that polarization navigation has high accuracy, is strongly robust, and performs well during fog and haze, clouds, and strong sunlight.

Alaskan Auroral All-Sky Images on the World Wide Web

NASA Technical Reports Server (NTRS)

Stenbaek-Nielsen, H. C.

1997-01-01

In response to a 1995 NASA SPDS announcement of support for preservation and distribution of important data sets online, the Geophysical Institute, University of Alaska Fairbanks, Alaska, proposed to provide World Wide Web access to the Poker Flat Auroral All-sky Camera images in real time. The Poker auroral all-sky camera is located in the Davis Science Operation Center at Poker Flat Rocket Range about 30 miles north-east of Fairbanks, Alaska, and is connected, through a microwave link, with the Geophysical Institute where we maintain the data base linked to the Web. To protect the low light-level all-sky TV camera from damage due to excessive light, we only operate during the winter season when the moon is down. The camera and data acquisition is now fully computer controlled. Digital images are transmitted each minute to the Web linked data base where the data are available in a number of different presentations: (1) Individual JPEG compressed images (1 minute resolution); (2) Time lapse MPEG movie of the stored images; and (3) A meridional plot of the entire night activity.

Impact of Orientation on the Vitamin D Weighted Exposure of a Human in an Urban Environment.

PubMed

Schrempf, Michael; Thuns, Nadine; Lange, Kezia; Seckmeyer, Gunther

2017-08-16

The vitamin D₃-weighted UV exposure of a human with vertical posture was calculated for urban locations to investigate the impact of orientation and obstructions on the exposure. Human exposure was calculated by using the 3D geometry of a human and integrating the radiance, i.e., the radiant energy from the direct solar beam and the diffuse sky radiation from different incident and azimuth angles. Obstructions of the sky are derived from hemispherical images, which are recorded by a digital camera with a fisheye lens. Due to the low reflectivity of most surfaces in the UV range, the radiance from obstructed sky regions was neglected. For spring equinox (21 March), the exposure of a human model with winter clothing in an environment where obstructions cover 40% of the sky varies by up to 25%, depending on the orientation of the human model to the sun. The calculation of the accumulated vitamin D₃-weighted exposure of a human with winter clothing walking during lunch break shows that human exposure is reduced by the obstruction of buildings and vegetation by 40%.

The Astronomical Photographic Data Archive

NASA Astrophysics Data System (ADS)

Cline, J. Donald; Barker, T.; Castelaz, M.

2010-01-01

Pisgah Astronomical Research Institute is the home of the Astronomical Photographic Data Archive (APDA), a national effort to preserve, archive, and digitize astronomical photographic plate collections. APDA was formed in 2007 and presently holds more than 100,000 plates and films from more than a dozen observatory collections. While the photographic data pre-dates modern observational data taken with electronic instruments, it is nevertheless of extremely high quality. When one considers 100,000 plates and films in the APDA collection, some with 100's or 1000's of objects per plate, and plates taken over 100 years the value of the data in APDA becomes apparent. In addition to the astronomical photographic data collections, APDA also possesses two high precision glass plate measuring machines, GAMMA I and GAMMA II that were built for NASA and the Space Telescope Science Institute. The measuring machines were used by a team of scientists under the leadership of the late Dr. Barry Lasker to develop the Guide Star Catalog and Digitized Sky Survey that guide and direct the Hubble Space Telescope. We will describe the current set of collections, plans for the measuring machines, and the efforts that have been made to assure preservation of plate collections.

Spatial Model of Sky Brightness Magnitude in Langkawi Island, Malaysia

NASA Astrophysics Data System (ADS)

Redzuan Tahar, Mohammad; Kamarudin, Farahana; Umar, Roslan; Khairul Amri Kamarudin, Mohd; Sabri, Nor Hazmin; Ahmad, Karzaman; Rahim, Sobri Abdul; Sharul Aikal Baharim, Mohd

2017-03-01

Sky brightness is an essential topic in the field of astronomy, especially for optical astronomical observations that need very clear and dark sky conditions. This study presents the spatial model of sky brightness magnitude in Langkawi Island, Malaysia. Two types of Sky Quality Meter (SQM) manufactured by Unihedron are used to measure the sky brightness on a moonless night (or when the Moon is below the horizon), when the sky is cloudless and the locations are at least 100 m from the nearest light source. The selected locations are marked by their GPS coordinates. The sky brightness data obtained in this study were interpolated and analyzed using a Geographic Information System (GIS), thus producing a spatial model of sky brightness that clearly shows the dark and bright sky areas in Langkawi Island. Surprisingly, our results show the existence of a few dark sites nearby areas of high human activity. The sky brightness of 21.45 mag arcsec{}-2 in the Johnson-Cousins V-band, as the average of sky brightness equivalent to 2.8 × {10}-4{cd} {{{m}}}-2 over the entire island, is an indication that the island is, overall, still relatively dark. However, the amount of development taking place might reduce the number in the near future as the island is famous as a holiday destination.

South Galactic Cap u-band Sky Survey (SCUSS): Data Release

NASA Astrophysics Data System (ADS)

Zou, Hu; Zhou, Xu; Jiang, Zhaoji; Peng, Xiyan; Fan, Dongwei; Fan, Xiaohui; Fan, Zhou; He, Boliang; Jing, Yipeng; Lesser, Michael; Li, Cheng; Ma, Jun; Nie, Jundan; Shen, Shiyin; Wang, Jiali; Wu, Zhenyu; Zhang, Tianmeng; Zhou, Zhimin

2016-02-01

The South Galactic Cap u-band Sky Survey (SCUSS) is a deep u-band imaging survey in the south Galactic cap using the 2.3 m Bok telescope. The survey observations were completed at the end of 2013, covering an area of about 5000 square degrees. We release the data in the region with an area of about 4000 deg2 that is mostly covered by the Sloan digital sky survey. The data products contain calibrated single-epoch images, stacked images, photometric catalogs, and a catalog of star proper motions derived by Peng et al. The median seeing and magnitude limit (5σ) are about 2.″0 and 23.2 mag, respectively. There are about 8 million objects having measurements of absolute proper motions. All the data and related documentations can be accessed through the SCUSS data release website http://batc.bao.ac.cn/Uband/data.html.

Target Selection for the SDSS-IV APOGEE-2 Survey

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zasowski, G.; Cohen, R. E.; Carlberg, J. K.

APOGEE-2 is a high-resolution, near-infrared spectroscopic survey observing ∼3 × 10{sup 5} stars across the entire sky. It is the successor to APOGEE and is part of the Sloan Digital Sky Survey IV (SDSS-IV). APOGEE-2 is expanding on APOGEE’s goals of addressing critical questions of stellar astrophysics, stellar populations, and Galactic chemodynamical evolution using (1) an enhanced set of target types and (2) a second spectrograph at Las Campanas Observatory in Chile. APOGEE-2 is targeting red giant branch and red clump stars, RR Lyrae, low-mass dwarf stars, young stellar objects, and numerous other Milky Way and Local Group sources across the entiremore » sky from both hemispheres. In this paper, we describe the APOGEE-2 observational design, target selection catalogs and algorithms, and the targeting-related documentation included in the SDSS data releases.« less

Lens and Camera Arrays for Sky Surveys and Space Surveillance

NASA Astrophysics Data System (ADS)

Ackermann, M.; Cox, D.; McGraw, J.; Zimmer, P.

2016-09-01

In recent years, a number of sky survey projects have chosen to use arrays of commercial cameras coupled with commercial photographic lenses to enable low-cost, wide-area observation. Projects such as SuperWASP, FAVOR, RAPTOR, Lotis, PANOPTES, and DragonFly rely on multiple cameras with commercial lenses to image wide areas of the sky each night. The sensors are usually commercial astronomical charge coupled devices (CCDs) or digital single reflex (DSLR) cameras, while the lenses are large-aperture, highend consumer items intended for general photography. While much of this equipment is very capable and relatively inexpensive, this approach comes with a number of significant limitations that reduce sensitivity and overall utility of the image data. The most frequently encountered limitations include lens vignetting, narrow spectral bandpass, and a relatively large point spread function. Understanding these limits helps to assess the utility of the data, and identify areas where advanced optical designs could significantly improve survey performance.

Global Sky Model (GSM): A Model of Diffuse Galactic Radio Emission from 10 MHz to 100 GHz

NASA Astrophysics Data System (ADS)

de Oliveira-Costa, Angelica; Tegmark, Max; Gaensler, B. M.; Jonas, Justin; Landecker, T. L.; Reich, Patricia

2010-11-01

Understanding diffuse Galactic radio emission is interesting both in its own right and for minimizing foreground contamination of cosmological measurements. Cosmic Microwave Background experiments have focused on frequencies > 10 GHz, whereas 21 cm tomography of the high redshift universe will mainly focus on < 0.2 GHz, for which less is currently known about Galactic emission. Motivated by this, we present a global sky model derived from all publicly available total power large-area radio surveys, digitized with optical character recognition when necessary and compiled into a uniform format, as well as the new Villa Elisa data extending the 1.4 GHz map to the entire sky. We quantify statistical and systematic uncertainties in these surveys by comparing them with various global multi-frequency model fits. We find that a principal component based model with only three components can fit the 11 most accurate data sets (at 10, 22, 45 & 408 MHz and 1.4, 2.3, 23, 33, 41, 61, 94 GHz) to an accuracy around 1%-10% depending on frequency and sky region. The data compilation and software returning a predicted all-sky map at any frequency from 10 MHz to 100 GHz are publicly available at the link below.

Modelling Digital Thunder

ERIC Educational Resources Information Center

Blanco, Francesco; La Rocca, Paola; Petta, Catia; Riggi, Francesco

2009-01-01

An educational model simulation of the sound produced by lightning in the sky has been employed to demonstrate realistic signatures of thunder and its connection to the particular structure of the lightning channel. Algorithms used in the past have been revisited and implemented, making use of current computer techniques. The basic properties of…

Elementary Student Knowledge Gains in the Digital Portable Planetarium

ERIC Educational Resources Information Center

Carsten-Conner, Laura D.; Larson, Angela M.; Arseneau, Jennifer; Herrick, Robert R.

2015-01-01

Immersive environments hold promise to provide unique and heightened sensory experiences that focus a learner's attention, and thus may be useful learning platforms. In particular, portable planetariums may be useful in advancing conceptual knowledge about the night sky, because they afford learners with Earth-based views of celestial motions,…

Northern Sky Variability Survey: Public Data Release

NASA Astrophysics Data System (ADS)

Woźniak, P. R.; Vestrand, W. T.; Akerlof, C. W.; Balsano, R.; Bloch, J.; Casperson, D.; Fletcher, S.; Gisler, G.; Kehoe, R.; Kinemuchi, K.; Lee, B. C.; Marshall, S.; McGowan, K. E.; McKay, T. A.; Rykoff, E. S.; Smith, D. A.; Szymanski, J.; Wren, J.

2004-04-01

The Northern Sky Variability Survey (NSVS) is a temporal record of the sky over the optical magnitude range from 8 to 15.5. It was conducted in the course of the first-generation Robotic Optical Transient Search Experiment (ROTSE-I) using a robotic system of four comounted unfiltered telephoto lenses equipped with CCD cameras. The survey was conducted from Los Alamos, New Mexico, and primarily covers the entire northern sky. Some data in southern fields between declinations 0° and -38° are also available, although with fewer epochs and noticeably lesser quality. The NSVS contains light curves for approximately 14 million objects. With a 1 yr baseline and typically 100-500 measurements per object, the NSVS is the most extensive record of stellar variability across the bright sky available today. In a median field, bright unsaturated stars attain a point-to-point photometric scatter of ~0.02 mag and position errors within 2". At Galactic latitudes |b|<20deg, the data quality is limited by severe blending due to the ~14" pixel size. We present basic characteristics of the data set and describe data collection, analysis, and distribution. All NSVS photometric measurements are available for on-line public access from the Sky Database for Objects in Time-Domain (SkyDOT) at Los Alamos National Laboratory. Copies of the full survey photometry may also be requested on tape. Based on observations obtained with the ROTSE-I robotic telescope, which was operated at Los Alamos National Laboratory.

Sky Quality Meter measurements in a colour-changing world

NASA Astrophysics Data System (ADS)

Sánchez de Miguel, A.; Aubé, M.; Zamorano, J.; Kocifaj, M.; Roby, J.; Tapia, C.

2017-05-01

The Sky Quality Meter (SQM) has become the most common device used to track the evolution of the brightness of the sky from polluted regions to first-class astronomical observatories. A vast database of SQM measurements already exists for many places in the world. Unfortunately, the SQM operates over a wide spectral band and its spectral response interacts with the sky's spectrum in a complex manner. This is why the optical signals are difficult to interpret when the data are recorded in regions with different sources of artificial light. The brightness of the night sky is linked in a complex way to ground-based light emissions, while taking into account atmospheric-induced optical distortion as well as spectral transformation from the underlying ground surfaces. While the spectral modulation of the sky's radiance has been recognized, it still remains poorly characterized and quantified. The impact of the SQM's spectral characteristics on sky-brightness measurements is analysed here for different light sources, including low- and high-pressure sodium lamps, PC-amber and white LEDs, metal halide and mercury lamps. We show that a routine conversion of radiance to magnitude is difficult, or rather impossible, because the average wavelength depends on actual atmospheric and environment conditions, the spectrum of the source and device-specific properties. We correlate SQM readings with both the Johnson astronomical photometry bands and the human system of visual perception, assuming different lighting technologies. These findings have direct implications for the processing of SQM data and for their improvement and/or remediation.

GLOBE at Night: a Worldwide Citizen-Science Program to Increase Awareness of Light Pollution by Measuring Night Sky Brightness

NASA Astrophysics Data System (ADS)

Walker, C. E.; Pompea, S. M.

2011-12-01

The emphasis in the international citizen-science, star-hunting campaign, GLOBE at Night, is in bringing awareness to the public on issues of light pollution. Light pollution threatens not only observatory sites and our "right to starlight", but can affect energy consumption, wildlife and health. GLOBE at Night has successfully reached a few 100,000 citizen-scientists. What has contributed to its success? Foundational resources are available to facilitate the public's participation in promoting dark skies awareness. The GLOBE at Night website explains clearly the simple-to-participate-in 5 step program and offers background information and interactive games on key concepts. To promote the campaign via popular social media, GLOBE at Night created Facebook and Twitter pages. The program has been expanded to include trainings of the general public, but especially educators in schools, museums and science centers, in unique ways. Education kits for dark skies awareness have been distributed at the training workshops. The kit includes material for a light shielding demonstration, a digital Sky Quality Meter and "Dark Skies Rangers" activities. The activities are on how unshielded light wastes energy, how light pollution affects wildlife and how one can participate in a citizen-science star-hunt like GLOBE at Night. To increase participation in the 2011 campaign, children and adults submitted their sky brightness measurements in real time with smart phones or tablets using the web application at www.globeatnight.org/webapp/. With smart phones and tablets, the location, date and time register automatically. For those without smart mobile devices, user-friendly tools on the GLOBE at Night report page were reconfigured to determine latitude and longitude more easily and accurately. As a proto-type for taking multiple measurements, people in Tucson found it easy to adopt a street and take measurements every mile for the length of the street. The grid of measurements canvassed the town, allowing for comparisons of light levels over time (hours, days, years) or searching for dark sky oases or light polluted areas. The increase to 2 campaigns in 2011 re-enforces these studies. The intent is to offer the program year-round for seasonal studies. The data can also be used to compare with datasets on wildlife, health, and energy consumption. Recently, NOAO and the Arizona Game and Fish Department have started a project with GLOBE at Night data and bat telemetry to examine a dark skies corridor in Tucson where the endangered bats fly. In addition, a 2nd new Web application (www.globeatnight.org/mapapp/) allows for mapping GLOBE at Night data points within a specified distance around a city or an area of choice. The resulting maps are bookmarkable and shareable. The presentation will highlight the education and outreach value of the program's resources and outcomes, lessons learned, successes and pitfalls in communicating awareness with the public and attracting young people to study science.

Crystal gazing. Part 2: Implications of advanced in digital data storage technology

NASA Technical Reports Server (NTRS)

Wells, D. C.

1984-01-01

During the next 5-10 years it is likely that the bit density available in digital mass storage systems (magnetic tapes, optical and magnetic disks) will be increased to such an extent that it will greatly exceed that of the conventional photographic emulsions like IIIaJ which are used in astronomy. These developments imply that it will soon be advantageous for astronomers to use microdensitometers to completely digitize all photographic plates soon after they are developed. Distribution of digital copies of sky surveys and the contents of plate vaults will probably become feasible within ten years. Copies of other astronomical archieves (e.g., Space Telescope) could also be distributed with the same techniques. The implications for designers of future microdensitometers are: (1) there will be a continuing need for precision digitization of large-format photographic imagery, and (2) that the need for real-time analysis of the output of microdensitometers will decrease.

SDSS-IV MaNGA IFS GALAXY SURVEY—SURVEY DESIGN, EXECUTION, AND INITIAL DATA QUALITY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yan, Renbin; Zhang, Kai; Bundy, Kevin

The MaNGA Survey (Mapping Nearby Galaxies at Apache Point Observatory) is one of three core programs in the Sloan Digital Sky Survey IV. It is obtaining integral field spectroscopy for 10,000 nearby galaxies at a spectral resolution of R  ∼ 2000 from 3622 to 10354 Å. The design of the survey is driven by a set of science requirements on the precision of estimates of the following properties: star formation rate surface density, gas metallicity, stellar population age, metallicity, and abundance ratio, and their gradients; stellar and gas kinematics; and enclosed gravitational mass as a function of radius. We describe how thesemore » science requirements set the depth of the observations and dictate sample selection. The majority of targeted galaxies are selected to ensure uniform spatial coverage in units of effective radius (R{sub e}) while maximizing spatial resolution. About two-thirds of the sample is covered out to 1.5 R{sub e} (Primary sample), and one-third of the sample is covered to 2.5 R{sub e} (Secondary sample). We describe the survey execution with details that would be useful in the design of similar future surveys. We also present statistics on the achieved data quality, specifically the point-spread function, sampling uniformity, spectral resolution, sky subtraction, and flux calibration. For our Primary sample, the median r -band signal-to-noise ratio is ∼70 per 1.4 Å pixel for spectra stacked between 1 R{sub e} and 1.5 R{sub e}. Measurements of various galaxy properties from the first-year data show that we are meeting or exceeding the defined requirements for the majority of our science goals.« less

SDSS-IV MaNGA IFS Galaxy Survey—Survey Design, Execution, and Initial Data Quality

NASA Astrophysics Data System (ADS)

Yan, Renbin; Bundy, Kevin; Law, David R.; Bershady, Matthew A.; Andrews, Brett; Cherinka, Brian; Diamond-Stanic, Aleksandar M.; Drory, Niv; MacDonald, Nicholas; Sánchez-Gallego, José R.; Thomas, Daniel; Wake, David A.; Weijmans, Anne-Marie; Westfall, Kyle B.; Zhang, Kai; Aragón-Salamanca, Alfonso; Belfiore, Francesco; Bizyaev, Dmitry; Blanc, Guillermo A.; Blanton, Michael R.; Brownstein, Joel; Cappellari, Michele; D'Souza, Richard; Emsellem, Eric; Fu, Hai; Gaulme, Patrick; Graham, Mark T.; Goddard, Daniel; Gunn, James E.; Harding, Paul; Jones, Amy; Kinemuchi, Karen; Li, Cheng; Li, Hongyu; Maiolino, Roberto; Mao, Shude; Maraston, Claudia; Masters, Karen; Merrifield, Michael R.; Oravetz, Daniel; Pan, Kaike; Parejko, John K.; Sanchez, Sebastian F.; Schlegel, David; Simmons, Audrey; Thanjavur, Karun; Tinker, Jeremy; Tremonti, Christy; van den Bosch, Remco; Zheng, Zheng

2016-12-01

The MaNGA Survey (Mapping Nearby Galaxies at Apache Point Observatory) is one of three core programs in the Sloan Digital Sky Survey IV. It is obtaining integral field spectroscopy for 10,000 nearby galaxies at a spectral resolution of R ˜ 2000 from 3622 to 10354 Å. The design of the survey is driven by a set of science requirements on the precision of estimates of the following properties: star formation rate surface density, gas metallicity, stellar population age, metallicity, and abundance ratio, and their gradients; stellar and gas kinematics; and enclosed gravitational mass as a function of radius. We describe how these science requirements set the depth of the observations and dictate sample selection. The majority of targeted galaxies are selected to ensure uniform spatial coverage in units of effective radius (R e ) while maximizing spatial resolution. About two-thirds of the sample is covered out to 1.5R e (Primary sample), and one-third of the sample is covered to 2.5R e (Secondary sample). We describe the survey execution with details that would be useful in the design of similar future surveys. We also present statistics on the achieved data quality, specifically the point-spread function, sampling uniformity, spectral resolution, sky subtraction, and flux calibration. For our Primary sample, the median r-band signal-to-noise ratio is ˜70 per 1.4 Å pixel for spectra stacked between 1R e and 1.5R e . Measurements of various galaxy properties from the first-year data show that we are meeting or exceeding the defined requirements for the majority of our science goals.

The ugrizYJHK luminosity distributions and densities from the combined MGC, SDSS and UKIDSS LAS data sets

NASA Astrophysics Data System (ADS)

Hill, David T.; Driver, Simon P.; Cameron, Ewan; Cross, Nicholas; Liske, Jochen; Robotham, Aaron

2010-05-01

We combine data from the Millennium Galaxy Catalogue, Sloan Digital Sky Survey and UKIRT Infrared Deep Sky Survey Large Area Survey to produce ugrizYJHK luminosity functions and densities from within a common, low-redshift volume (z < 0.1, ~ 71000h-31 Mpc3 for L* systems) with 100 per cent spectroscopic completeness. In the optical the fitted Schechter functions are comparable in shape to those previously reported values but with higher normalizations (typically 0, 30, 20, 15, 5 per cent higher φ* values in u, g, r, i, z, respectively, over those reported by the SDSS team). We attribute these to differences in the redshift ranges probed, incompleteness and adopted normalization methods. In the near-IR (NIR) we find significantly different Schechter function parameters (mainly in the M* values) to those previously reported and attribute this to the improvement in the quality of the imaging data over previous studies. This is the first homogeneous measurement of the extragalactic luminosity density which fully samples both the optical and NIR regimes. Unlike previous compilations that have noted a discontinuity between the optical and NIR regimes our homogeneous data set shows a smooth cosmic spectral energy distribution (CSED). After correcting for dust attenuation we compare our CSED to the expected values based on recent constraints on the cosmic star formation history and the initial mass function.

The BlueSky Smoke Modeling Framework: Recent Developments

NASA Astrophysics Data System (ADS)

Sullivan, D. C.; Larkin, N.; Raffuse, S. M.; Strand, T.; ONeill, S. M.; Leung, F. T.; Qu, J. J.; Hao, X.

2012-12-01

BlueSky systems—a set of decision support tools including SmartFire and the BlueSky Framework—aid public policy decision makers and scientific researchers in evaluating the air quality impacts of fires. Smoke and fire managers use BlueSky systems in decisions about prescribed burns and wildland firefighting. Air quality agencies use BlueSky systems to support decisions related to air quality regulations. We will discuss a range of recent improvements to the BlueSky systems, as well as examples of applications and future plans. BlueSky systems have the flexibility to accept basic fire information from virtually any source and can reconcile multiple information sources so that duplication of fire records is eliminated. BlueSky systems currently apply information from (1) the National Oceanic and Atmospheric Administration's (NOAA) Hazard Mapping System (HMS), which represents remotely sensed data from the Moderate Resolution Imaging Spectroradiometer (MODIS), Advanced Very High Resolution Radiometer (AVHRR), and Geostationary Operational Environmental Satellites (GOES); (2) the Monitoring Trends in Burn Severity (MTBS) interagency project, which derives fire perimeters from Landsat 30-meter burn scars; (3) the Geospatial Multi-Agency Coordination Group (GeoMAC), which produces helicopter-flown burn perimeters; and (4) ground-based fire reports, such as the ICS-209 reports managed by the National Wildfire Coordinating Group. Efforts are currently underway to streamline the use of additional ground-based systems, such as states' prescribed burn databases. BlueSky systems were recently modified to address known uncertainties in smoke modeling associated with (1) estimates of biomass consumption derived from sparse fuel moisture data, and (2) models of plume injection heights. Additional sources of remotely sensed data are being applied to address these issues as follows: - The National Aeronautics and Space Administration's (NASA) Tropical Rainfall Measuring Mission (TRMM) Multi-satellite Precipitation Analysis Real-Time (TMPA-RT) data set is being used to improve dead fuel moisture estimates. - EastFire live fuel moisture estimates, which are derived from NASA's MODIS direct broadcast, are being used to improve live fuel moisture estimates. - NASA's Multi-angle Imaging Spectroradiometer (MISR) stereo heights are being used to improve estimates of plume injection heights. Further, the Fire Location and Modeling of Burning Emissions (FLAMBÉ) model was incorporated into the BlueSky Framework as an alternative means of calculating fire emissions. FLAMBÉ directly estimates emissions on the basis of fire detections and radiance measures from NASA's MODIS and NOAA's GOES satellites. (The authors gratefully acknowledge NASA's Applied Sciences Program [Grant Nos. NN506AB52A and NNX09AV76G)], the USDA Forest Service, and the Joint Fire Science Program for their support.)

Time Domain Astronomy with the Harvard Plates: from Cepheids to DASCH

NASA Astrophysics Data System (ADS)

Grindlay, Jonathan E.

2014-06-01

The ~500,000 Harvard glass plate photographic negatives are the world’s largest and most complete (full sky; 107y time span) database for Time Domain Astronomy (TDA) on days-months-decades to century timescales. With plate fields of view ranging from 3o - 30o exposed quasi-randomly full sky from 1885 - 1992, any object is observed ~1000 - 3000 times, with limiting magnitudes ranging from B =12-18. I briefly review some of the colorful history of this massive plate-taking project and a few of the pivotal discoveries (e.g. the “Leavitt Law” for the Cepheid Period-Luminosity relation) made by visual studies of the plates by the true TDA pioneers, the likely <300 different visual users of the plates. I then describe our Digital Access to a Sky Century @ Harvard (DASCH) project to fully digitize and reduce this wealth of data 1 Pb) and provide it on spinning disk to the full astronomical community and public. Using the full-sky APASS catalog giving BVR magnitudes (for V ~9-17) as well as GSC2.3.2 for both fainter and brighter stars, DASCH does spatially resolved (0.25o -0.6o bins) photometric calibrations to derive B magnitudes with rm 0.1mag over the full plate and over the (typically) ~6-8 different principal plate series (telescopes and plate scales) covering any given object, along with ~0.3-1 arcsec astrometry (depending on plate scale) for each stellar object averaged over ~1year. The high speed/precision scanner, plate processing, and analysis pipeline have now enabled the first data releases (DR1-DR3) of 12 to cover full sky and already enabled a wealth of new discoveries. I describe a few examples, such as: K2III giants with decadal variations; a new class of Symbiotic novae; ~50-100y recurrence times for black hole X-ray binary outbursts; and QPOs from 3C273. The DASCH data are increasingly available 15% now; 100% in 3.5y) for TDA on largely unexplored timescales. We are grateful to NSF for support with grants AST-0407380, AST-0909073 and AST-1313370.

Reconstruction of Sky Illumination Domes from Ground-Based Panoramas

NASA Astrophysics Data System (ADS)

Coubard, F.; Lelégard, L.; Brédif, M.; Paparoditis, N.; Briottet, X.

2012-07-01

The knowledge of the sky illumination is important for radiometric corrections and for computer graphics applications such as relighting or augmented reality. We propose an approach to compute environment maps, representing the sky radiance, from a set of ground-based images acquired by a panoramic acquisition system, for instance a mobile-mapping system. These images can be affected by important radiometric artifacts, such as bloom or overexposure. A Perez radiance model is estimated with the blue sky pixels of the images, and used to compute additive corrections in order to reduce these radiometric artifacts. The sky pixels are then aggregated in an environment map, which still suffers from discontinuities on stitching edges. The influence of the quality of estimated sky radiance on the simulated light signal is measured quantitatively on a simple synthetic urban scene; in our case, the maximal error for the total sensor radiance is about 10%.

A digital-receiver for the MurchisonWidefield Array

NASA Astrophysics Data System (ADS)

Prabu, Thiagaraj; Srivani, K. S.; Roshi, D. Anish; Kamini, P. A.; Madhavi, S.; Emrich, David; Crosse, Brian; Williams, Andrew J.; Waterson, Mark; Deshpande, Avinash A.; Shankar, N. Udaya; Subrahmanyan, Ravi; Briggs, Frank H.; Goeke, Robert F.; Tingay, Steven J.; Johnston-Hollitt, Melanie; R, Gopalakrishna M.; Morgan, Edward H.; Pathikulangara, Joseph; Bunton, John D.; Hampson, Grant; Williams, Christopher; Ord, Stephen M.; Wayth, Randall B.; Kumar, Deepak; Morales, Miguel F.; deSouza, Ludi; Kratzenberg, Eric; Pallot, D.; McWhirter, Russell; Hazelton, Bryna J.; Arcus, Wayne; Barnes, David G.; Bernardi, Gianni; Booler, T.; Bowman, Judd D.; Cappallo, Roger J.; Corey, Brian E.; Greenhill, Lincoln J.; Herne, David; Hewitt, Jacqueline N.; Kaplan, David L.; Kasper, Justin C.; Kincaid, Barton B.; Koenig, Ronald; Lonsdale, Colin J.; Lynch, Mervyn J.; Mitchell, Daniel A.; Oberoi, Divya; Remillard, Ronald A.; Rogers, Alan E.; Salah, Joseph E.; Sault, Robert J.; Stevens, Jamie B.; Tremblay, S.; Webster, Rachel L.; Whitney, Alan R.; Wyithe, Stuart B.

2015-03-01

An FPGA-based digital-receiver has been developed for a low-frequency imaging radio interferometer, the Murchison Widefield Array (MWA). The MWA, located at the Murchison Radio-astronomy Observatory (MRO) in Western Australia, consists of 128 dual-polarized aperture-array elements (tiles) operating between 80 and 300 MHz, with a total processed bandwidth of 30.72 MHz for each polarization. Radio-frequency signals from the tiles are amplified and band limited using analog signal conditioning units; sampled and channelized by digital-receivers. The signals from eight tiles are processed by a single digital-receiver, thus requiring 16 digital-receivers for the MWA. The main function of the digital-receivers is to digitize the broad-band signals from each tile, channelize them to form the sky-band, and transport it through optical fibers to a centrally located correlator for further processing. The digital-receiver firmware also implements functions to measure the signal power, perform power equalization across the band, detect interference-like events, and invoke diagnostic modes. The digital-receiver is controlled by high-level programs running on a single-board-computer. This paper presents the digital-receiver design, implementation, current status, and plans for future enhancements.

Image digitising and analysis of outflows from young stars

NASA Astrophysics Data System (ADS)

Zealey, W. J.; Mader, S. L.

1997-08-01

We present IIIaJ, IIIaF and IVN band images of Herbig-Haro objects digitised from the ESO/SERC Southern Sky Survey plates. These form part of a digital image database of southern HH objects, which allows the identification of emission and reflection nebulosity and the location of the obscured sources of outflows.

A green flash from the Moon; BOSS measures the distant universe in 3D; Cuts in Parliament; When asteroids collide; SpaceX to beat China

NASA Astrophysics Data System (ADS)

2011-06-01

The biggest 3D map of the distant universe, based on the intergalactic hydrogen distribution as well as on the distribution of visible galaxies, has been produced by the Sloan Digital Sky Survey (SDSS-III).

RUNAWAY M DWARF CANDIDATES FROM THE SLOAN DIGITAL SKY SURVEY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Favia, Andrej; West, Andrew A.; Theissen, Christopher A., E-mail: andrej.favia@umit.maine.edu

2015-11-01

We present a sample of 20 runaway M dwarf candidates (RdMs) within 1 kpc of the Sun whose Galactocentric (GC) velocities exceed 400 km s{sup −1}. The candidates were selected from the Sloan Digital Sky Survey (SDSS) DR7 M Dwarf Catalog of West et al. Our RdMs have SDSS+USNO-B proper motions that are consistent with those recorded in the PPMXL, LSPM, and combined Wide-field Infrared Survey Explorer +SDSS+Two-micron All-sky Survey catalogs. Sixteen RdMs are classified as dwarfs, while the remaining four RdMs are subdwarfs. We model the Galactic potential using a bulge-disk-halo profile. Our fastest RdM, with a GC velocitymore » of 658.5 ± 236.9 km s{sup −1}, is a possible hypervelocity candidate, as it is unbound in 77% of our simulations. About half of our RdMs have kinematics that are consistent with ejection from the Galactic center. Seven of our RdMs have kinematics consistent with an ejection scenario from M31 or M32 to within 2 σ , although our distance-limited survey makes such a realization unlikely. No more than four of our RdMs may have originated from the Leo stream. We propose that to within measurement errors, most of our bound RdMs are likely disk runaways or halo objects, and may have been accelerated through a series of multi-body interactions within the Galactic disk or possibly supernovae explosions.« less

Taking the Observatory to the Astronomer

NASA Astrophysics Data System (ADS)

Bisque, T. M.

1997-05-01

Since 1992, Software Bisque's Remote Astronomy Software has been used by the Mt. Wilson Institute to allow interactive control of a 24" telescope and digital camera via modem. Software Bisque now introduces a comparable, relatively low-cost observatory system that allows powerful, yet "user-friendly" telescope and CCD camera control via the Internet. Utilizing software developed for the Windows 95/NT operating systems, the system offers point-and-click access to comprehensive celestial databases, extremely accurate telescope pointing, rapid download of digital CCD images by one or many users and flexible image processing software for data reduction and analysis. Our presentation will describe how the power of the personal computer has been leveraged to provide professional-level tools to the amateur astronomer, and include a description of this system's software and hardware components. The system software includes TheSky Astronomy Software?, CCDSoft CCD Astronomy Software?, TPoint Telescope Pointing Analysis System? software, Orchestrate? and, optionally, the RealSky CDs. The system hardware includes the Paramount GT-1100? Robotic Telescope Mount, as well as third party CCD cameras, focusers and optical tube assemblies.

Discovery of four doubly imaged quasar lenses from the Sloan digital sky survey

DOE Office of Scientific and Technical Information (OSTI.GOV)

Inada, Naohisa; Oguri, Masamune; Rusu, Cristian E.

2014-06-01

We report the discovery of four doubly imaged quasar lenses. All the four systems are selected as lensed quasar candidates from the Sloan Digital Sky Survey data. We confirm their lensing hypothesis with additional imaging and spectroscopic follow-up observations. The discovered lenses are SDSS J0743+2457 with the source redshift z{sub s} = 2.165, the lens redshift z{sub l} = 0.381, and the image separation θ = 1.''034, SDSS J1128+2402 with z{sub s} = 1.608 and θ = 0.''844, SDSS J1405+0959 with z{sub s} = 1.810, z{sub l} ≈ 0.66, and θ = 1.''978, and SDSS J1515+1511 with z{sub s} =more » 2.054, z{sub l} = 0.742, and θ = 1.''989. It is difficult to estimate the lens redshift of SDSS J1128+2402 from the current data. Two of the four systems (SDSS J1405+0959 and SDSS J1515+1511) are included in our final statistical lens sample to derive constraints on dark energy and the evolution of massive galaxies.« less

Improved Photometry for the DASCH Pipeline

NASA Astrophysics Data System (ADS)

Tang, Sumin; Grindlay, Jonathan; Los, Edward; Servillat, Mathieu

2013-07-01

The Digital Access to a Sky Century@Harvard (DASCH) project is digitizing the ˜500,000 glass plate images obtained (full sky) by the Harvard College Observatory from 1885 to 1992. Astrometry and photometry for each resolved object are derived with photometric rms values of ˜0.15 mag for the initial photometry analysis pipeline. Here we describe new developments for DASCH photometry, applied to the Kepler field, that have yielded further improvements, including better identification of image blends and plate defects by measuring image profiles and astrometric deviations. A local calibration procedure using nearby stars in a similar magnitude range as the program star (similar to what has been done for visual photometry from the plates) yields additional improvement for a net photometric rms of ˜0.1 mag. We also describe statistical measures of light curves that are now used in the DASCH pipeline processing to identify new variables autonomously. The DASCH photometry methods described here are used in the pipeline processing for the data releases of DASCH data,5 as well as for a forthcoming paper on the long-term variables discovered by DASCH in the Kepler field.

VizieR Online Data Catalog: WISE Preliminary Data Release (Cutri+ 2011)

NASA Astrophysics Data System (ADS)

Cutri, R. M.; et al.

2012-01-01

The Wide-field Infrared Survey Explorer (WISE; see Wright et al. 2010AJ....140.1868W) is a NASA Medium Class Explorer mission that conducted a digital imaging survey of the entire sky in the 3.4, 4.6, 12 and 22um mid-infrared bandpasses (hereafter W1, W2, W3 and W4). WISE will produce and release to the world astronomical and educational communities and general public a digital Image Atlas covering the sky in the four survey bands, and a reliable Source Catalog containing accurate photometry and astrometry for over 300 million objects. The WISE Catalog and Atlas will enable a broad variety of research efforts ranging from the search for the closest stars and brown dwarfs to the most luminous galaxies in the Universe. WISE science data products will serve as an important reference data set for planning observations and interpreting data obtained with future ground and space-borne observatories, such as JWST. WISE was launched on 2009-12-14 from Vandenberg SLC2W. (1 data file).

APOGEE cryostat design

NASA Astrophysics Data System (ADS)

Blank, Basil; Henderson, Chuck; Wilson, John C.; Hearty, Fred R.; Skrutskie, Michael F.; O'Brien, Thomas P.; Majewski, Steven R.; Schiavon, Ricardo; Maseman, Paul; Brunner, Sophia; Burton, Adam; Walker, Eric

2010-07-01

The Apache Point Observatory Galactic Evolution Experiment (APOGEE) is a survey of all Galactic stellar populations that will employ an R=30,000 spectrograph operating in the near-infrared (1.5-1.7μm) wavelength range. The fiber-fed spectrograph is housed in a large (1.4m x 2.3m x 1.3m) stainless steel cryostat or Dewar that is LN2-cooled and will be located in a building near the 2.5m Sloan Digital Sky Survey (SDSS) telescope to which it will be coupled. The choice of shell material and configuration was an optimization among optics packaging, weight, strength, external dimensions, rigging and transportation, the available integration and testing room, and the ultimate instrument room at APO. Internals are fabricated of more traditional 6061-T6 aluminum which is well proven in cryogenic applications. An active thermal shield with MLI blanketing yields an extremely low thermal load of 45-50 watts for this ~3000 liter instrument. Cryostat design details are discussed with applicable constraints and trade decisions. APOGEE is one of four experiments that are part of Sloan Digital Sky Survey III (SDSS-III).

The Locus of Stars, Galaxies, and QSOs. in SDSS Filters

NASA Astrophysics Data System (ADS)

Newberg, H.; Richards, G.; Lenz, D.; Fan, X.; Richmond, M.; Yanny, B.

1997-12-01

We present a catalog of over 2000 stars, QSOs, and galaxies in five optical passbands (u*, g*, r*, i*, and z*) that will be used by the Sloan Digital Sky Survey. The sources are brighter than 19.5 in r* (which is similar to Gunn r), and were selected from 15 fields covering half a square degree; about half of the objects have a measured u* flux. The statistical error in the photometry is typically a few percent. The systematic error is less than about 10 percent. The data was obtained on the USNO 1-m in Flagstaff, Arizona. The positions of the stars in color space are compared with Kurucz model stars, and show quite good agreement. The stellar locus, as well as the Kurucz model fits, show that the locus is shaped like a ribbon winding through color-color-color space, as discovered by Newberg and Yanny (1997). The catalog will be used to tune selection algorithms that will select spectroscopic targets from the phometric data produced by the Sloan Digital Sky Survey.

A Search for Nontoroidal Topological Lensing in the Sloan Digital Sky Survey Quasar Catalog

NASA Astrophysics Data System (ADS)

Fujii, Hirokazu; Yoshii, Yuzuru

2013-08-01

Flat space models with multiply connected topology, which have compact dimensions, are tested against the distribution of high-redshift (z >= 4) quasars of the Sloan Digital Sky Survey (SDSS). When the compact dimensions are smaller in size than the observed universe, topological lensing occurs, in which multiple images of single objects (ghost images) are observed. We improve on the recently introduced method to identify ghost images by means of four-point statistics. Our method is valid for any of the 17 multiply connected flat models, including nontoroidal ones that are compacted by screw motions or glide reflection. Applying the method to the data revealed one possible case of topological lensing caused by sixth-turn screw motion, however, it is consistent with the simply connected model by this test alone. Moreover, simulations suggest that we cannot exclude the other space models despite the absence of their signatures. This uncertainty mainly originates from the patchy coverage of SDSS in the south Galactic cap, and this situation will be improved by future wide-field spectroscopic surveys.

GALAXY ZOO MORPHOLOGY AND PHOTOMETRIC REDSHIFTS IN THE SLOAN DIGITAL SKY SURVEY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Way, M. J.

It has recently been demonstrated that one can accurately derive galaxy morphology from particular primary and secondary isophotal shape estimates in the Sloan Digital Sky Survey (SDSS) imaging catalog. This was accomplished by applying Machine Learning techniques to the Galaxy Zoo morphology catalog. Using the broad bandpass photometry of the SDSS in combination with precise knowledge of galaxy morphology should help in estimating more accurate photometric redshifts for galaxies. Using the Galaxy Zoo separation for spirals and ellipticals in combination with SDSS photometry we attempt to calculate photometric redshifts. In the best case we find that the root-mean-square error formore » luminous red galaxies classified as ellipticals is as low as 0.0118. Given these promising results we believe better photometric redshift estimates for all galaxies in the SDSS ({approx}350 million) will be feasible if researchers can also leverage their derived morphologies via Machine Learning. These initial results look to be promising for those interested in estimating weak lensing, baryonic acoustic oscillation, and other fields dependent upon accurate photometric redshifts.« less

ELUCID - Exploring the Local Universe with ReConstructed Initial Density Field III: Constrained Simulation in the SDSS Volume

NASA Astrophysics Data System (ADS)

Wang, Huiyuan; Mo, H. J.; Yang, Xiaohu; Zhang, Youcai; Shi, JingJing; Jing, Y. P.; Liu, Chengze; Li, Shijie; Kang, Xi; Gao, Yang

2016-11-01

A method we developed recently for the reconstruction of the initial density field in the nearby universe is applied to the Sloan Digital Sky Survey Data Release 7. A high-resolution N-body constrained simulation (CS) of the reconstructed initial conditions, with 30723 particles evolved in a 500 {h}-1 {Mpc} box, is carried out and analyzed in terms of the statistical properties of the final density field and its relation with the distribution of Sloan Digital Sky Survey galaxies. We find that the statistical properties of the cosmic web and the halo populations are accurately reproduced in the CS. The galaxy density field is strongly correlated with the CS density field, with a bias that depends on both galaxy luminosity and color. Our further investigations show that the CS provides robust quantities describing the environments within which the observed galaxies and galaxy systems reside. Cosmic variance is greatly reduced in the CS so that the statistical uncertainties can be controlled effectively, even for samples of small volumes.

The Missing Link: Early Methane ("T") Dwarfs in the Sloan Digital Sky Survey.

PubMed

Leggett; Geballe; Fan; Schneider; Gunn; Lupton; Knapp; Strauss; McDaniel; Golimowski; Henry; Peng; Tsvetanov; Uomoto; Zheng; Hill; Ramsey; Anderson; Annis; Bahcall; Brinkmann; Chen; Csabai; Fukugita; Hennessy; Hindsley; Ivezic; Lamb; Munn; Pier; Schlegel; Smith; Stoughton; Thakar; York

2000-06-10

We report the discovery of three cool brown dwarfs that fall in the effective temperature gap between the latest L dwarfs currently known, with no methane absorption bands in the 1-2.5 µm range, and the previously known methane (T) dwarfs, whose spectra are dominated by methane and water. The newly discovered objects were detected as very red objects in the Sloan Digital Sky Survey imaging data and have JHK colors between the red L dwarfs and the blue Gl 229B-like T dwarfs. They show both CO and CH(4) absorption in their near-infrared spectra in addition to H(2)O, with weaker CH(4) absorption features in the H and K bands than those in all other methane dwarfs reported to date. Due to the presence of CH(4) in these bands, we propose that these objects are early T dwarfs. The three form part of the brown dwarf spectral sequence and fill in the large gap in the overall spectral sequence from the hottest main-sequence stars to the coolest methane dwarfs currently known.

Polarization patterns of the twilight sky

NASA Astrophysics Data System (ADS)

Cronin, Thomas W.; Warrant, Eric J.; Greiner, Birgit

2005-08-01

Although natural light sources produce depolarized light, patterns of partially linearly polarized light appear in the sky due to scattering from air molecules, dust, and aerosols. Many animals, including bees and ants, orient themselves to patterns of polarization that are present in daytime skies, when the intensity is high and skylight polarization is strong and predictable. The halicitid bee Megalopta genalis inhabits rainforests in Central America. Unlike typical bees, it forages before sunrise and after sunset, when light intensities under the forest canopy are very low, and must find its way to food sources and return to its nest in visually challenging circumstances. An important cue for the orientation could be patterns of polarization in the twilight sky. Therefore, we used a calibrated digital camera to image skylight polarization in an overhead patch of sky, 87.6° across, before dawn on Barro Colorado Island in Panama, where the bees are found. We simultaneously measured the spectral properties of polarized light in a cloudless patch of sky 15° across centered on the zenith. We also performed full-sky imaging of polarization before dawn and after dusk on Lizard Island in Australia, another tropical island. During twilight, celestial polarized light occurs in a wide band stretching perpendicular to the location of the hidden sun and reaching typical degrees of polarization near 80% at wavelengths >600 nm. This pattern appears about 45 minutes before local sunrise or disappears 45 minutes after local sunset (about 20 minutes after the onset of astronomical twilight at dawn, or before its end at dusk) and extends with little change through the entire twilight period. Such a strong and reliable orientation cue could be used for flight orientation by any animal with polarization sensitivity that navigates during twilight.

[The backgroud sky subtraction around [OIII] line in LAMOST QSO spectra].

PubMed

Shi, Zhi-Xin; Comte, Georges; Luo, A-Li; Tu, Liang-Ping; Zhao, Yong-Heng; Wu, Fu-Chao

2014-11-01

At present, most sky-subtraction methods focus on the full spectrum, not the particular location, especially for the backgroud sky around [OIII] line which is very important to low redshift quasars. A new method to precisely subtract sky lines in local region is proposed in the present paper, which sloves the problem that the width of Hβ-[OIII] line is effected by the backgroud sky subtraction. The exprimental results show that, for different redshift quasars, the spectral quality has been significantly improved using our method relative to the original batch program by LAMOST. It provides a complementary solution for the small part of LAMOST spectra which are not well handled by LAMOST 2D pipeline. Meanwhile, This method has been used in searching for candidates of double-peaked Active Galactic Nuclei.

A Survey of z ~ 6 Quasars in the Sloan Digital Sky Survey Deep Stripe. I. A Flux-Limited Sample at zAB < 21

NASA Astrophysics Data System (ADS)

Jiang, Linhua; Fan, Xiaohui; Annis, James; Becker, Robert H.; White, Richard L.; Chiu, Kuenley; Lin, Huan; Lupton, Robert H.; Richards, Gordon T.; Strauss, Michael A.; Jester, Sebastian; Schneider, Donald P.

2008-03-01

We present the discovery of five quasars at z ~ 6 selected from 260 deg2 of the Sloan Digital Sky Survey (SDSS) southern survey, a deep imaging survey obtained by repeatedly scanning a stripe along the celestial equator. The five quasars with 20 < zAB < 21 are 1-2 magnitudes fainter than the luminous z ~ 6 quasars discovered in the SDSS main survey. One of them was independently discovered by the UKIRT Infrared Deep Sky Survey. These quasars, combined with another z ~ 6 quasar known in this region, make a complete flux-limited quasar sample at zAB < 21. The sample spans the redshift range 5.85 <= z <= 6.12 and the luminosity range -26.5 <= M 1450 <= -25.4 (H 0 = 70 km s-1 Mpc-1, Ω m = 0.3, and ΩΛ = 0.7). We use the 1/Va method to determine that the comoving quasar spatial density at langzrang = 6.0 and langM 1450rang = -25.8 is (5.0 ± 2.1) × 10-9 Mpc-3 mag-1. We model the bright-end quasar luminosity function (QLF) at z ~ 6 as a power law Φ(L 1450) vprop L β 1450. The slope β calculated from a combination of our sample and the luminous SDSS quasar sample is -3.1 ± 0.4, significantly steeper than the slope of the QLF at z ~ 4. Based on the derived QLF, we find that the quasar/active galactic nucleus (AGN) population cannot provide enough photons to ionize the intergalactic medium (IGM) at z ~ 6 unless the IGM is very homogeneous and the luminosity (L*1450) at which the QLF power law breaks is very low. Based on observations obtained with the Sloan Digital Sky Survey, which is owned and operated by the Astrophysical Research Consortium; the MMT Observatory, a joint facility of the University of Arizona and the Smithsonian Institution; the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile; the W.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration, and was made possible by the generous financial support of the W.M. Keck Foundation.

Exploring the Variable Sky with Linear. 1. Photometric Recalibration with the Sloan Digital Sky Survey

DTIC Science & Technology

2011-12-01

encoded as a 64-bit integer number theta_2massd Distance in arcsec from the 2MASS source J 2MASS J-band magnitude JErr 2MASS J-band magnitude error H... 2MASS H-band magnitude HErr 2MASS H-band magnitude error K 2MASS K-band magnitude KErr 2MASS K-band magnitude error jh 2MASS J−H color (corrected for...extinction, j − h = (J − 0.327rExt) − (H − 0.209rExt)) hk 2MASS H−K color (corrected for extinction, h− k = (H − 0.209rExt) − (K − 0.133rExt)) jk

ASERA: A Spectrum Eye Recognition Assistant

NASA Astrophysics Data System (ADS)

Yuan, Hailong; Zhang, Haotong; Zhang, Yanxia; Lei, Yajuan; Dong, Yiqiao; Zhao, Yongheng

2018-04-01

ASERA, ASpectrum Eye Recognition Assistant, aids in quasar spectral recognition and redshift measurement and can also be used to recognize various types of spectra of stars, galaxies and AGNs (Active Galactic Nucleus). This interactive software allows users to visualize observed spectra, superimpose template spectra from the Sloan Digital Sky Survey (SDSS), and interactively access related spectral line information. ASERA is an efficient and user-friendly semi-automated toolkit for the accurate classification of spectra observed by LAMOST (the Large Sky Area Multi-object Fiber Spectroscopic Telescope) and is available as a standalone Java application and as a Java applet. The software offers several functions, including wavelength and flux scale settings, zoom in and out, redshift estimation, and spectral line identification.

Impact of Orientation on the Vitamin D Weighted Exposure of a Human in an Urban Environment

PubMed Central

Schrempf, Michael; Thuns, Nadine; Lange, Kezia

2017-01-01

The vitamin D3-weighted UV exposure of a human with vertical posture was calculated for urban locations to investigate the impact of orientation and obstructions on the exposure. Human exposure was calculated by using the 3D geometry of a human and integrating the radiance, i.e., the radiant energy from the direct solar beam and the diffuse sky radiation from different incident and azimuth angles. Obstructions of the sky are derived from hemispherical images, which are recorded by a digital camera with a fisheye lens. Due to the low reflectivity of most surfaces in the UV range, the radiance from obstructed sky regions was neglected. For spring equinox (21 March), the exposure of a human model with winter clothing in an environment where obstructions cover 40% of the sky varies by up to 25%, depending on the orientation of the human model to the sun. The calculation of the accumulated vitamin D3-weighted exposure of a human with winter clothing walking during lunch break shows that human exposure is reduced by the obstruction of buildings and vegetation by 40%. PMID:28813022

Galaxy Number Counts from the Sloan Digital Sky Survey Commissioning Data

NASA Astrophysics Data System (ADS)

Yasuda, Naoki; Fukugita, Masataka; Narayanan, Vijay K.; Lupton, Robert H.; Strateva, Iskra; Strauss, Michael A.; Ivezić, Željko; Kim, Rita S. J.; Hogg, David W.; Weinberg, David H.; Shimasaku, Kazuhiro; Loveday, Jon; Annis, James; Bahcall, Neta A.; Blanton, Michael; Brinkmann, Jon; Brunner, Robert J.; Connolly, Andrew J.; Csabai, István; Doi, Mamoru; Hamabe, Masaru; Ichikawa, Shin-Ichi; Ichikawa, Takashi; Johnston, David E.; Knapp, G. R.; Kunszt, Peter Z.; Lamb, D. Q.; McKay, Timothy A.; Munn, Jeffrey A.; Nichol, Robert C.; Okamura, Sadanori; Schneider, Donald P.; Szokoly, Gyula P.; Vogeley, Michael S.; Watanabe, Masaru; York, Donald G.

2001-09-01

We present bright galaxy number counts in five broad bands (u', g', r', i', z') from imaging data taken during the commissioning phase of the Sloan Digital Sky Survey (SDSS). The counts are derived from two independent stripes of imaging scans along the celestial equator, one each toward the northern and the southern Galactic cap, covering about 230 and 210 deg2, respectively. A careful study is made to verify the reliability of the photometric catalog. For galaxies brighter than r*=16, the catalog produced by automated software is examined against eye inspection of all objects. Statistically meaningful results on the galaxy counts are obtained in the magnitude range 12<=r*<=21, using a sample of 900,000 galaxies. The counts from the two stripes differ by about 30% at magnitudes brighter than r*=15.5, consistent with a local 2 σ fluctuation due to large-scale structure in the galaxy distribution. The shape of the number counts-magnitude relation brighter than r*=16 is well characterized by N~100.6m, the relation expected for a homogeneous galaxy distribution in a ``Euclidean'' universe. In the magnitude range 16

Two More Candidate AM Canum Venaticorum (am CVn) Binaries from the Sloan Digital Sky Survey

NASA Astrophysics Data System (ADS)

Anderson, Scott F.; Becker, Andrew C.; Haggard, Daryl; Prieto, Jose Luis; Knapp, Gillian R.; Sako, Masao; Halford, Kelly E.; Jha, Saurabh; Martin, Blake; Holtzman, Jon; Frieman, Joshua A.; Garnavich, Peter M.; Hayward, Suzanne; Ivezić, Željko; Mukadam, Anjum S.; Sesar, Branimir; Szkody, Paula; Malanushenko, Viktor; Richmond, Michael W.; Schneider, Donald P.; York, Donald G.

2008-06-01

AM CVn systems are a select group of ultracompact binaries with the shortest orbital periods of any known binary subclass; mass transfer is likely from a low-mass (partially-)degenerate secondary onto a white dwarf primary, driven by gravitational radiation. In the past few years, the Sloan Digital Sky Survey (SDSS) has provided five new AM CVns. Here we report on two further candidates selected from more recent SDSS data. SDSS J1208+3550 is similar to the earlier SDSS discoveries, recognized as an AM CVn via its distinctive spectrum which is dominated by helium emission. From the expanded SDSS Data Release 6 (DR6) spectroscopic area, we provide an updated surface density estimate for such AM CVns of order 10-3.1-10-2.5 deg-2 for 15 < g < 20.5. In addition, we present another new candidate AM CVn, SDSS J2047+0008, which was discovered in the course of follow-up of SDSS-II supernova candidates. It shows nova-like outbursts in multi-epoch imaging data; in contrast to the other SDSS AM CVn discoveries, its (outburst) spectrum is dominated by helium absorption lines, reminiscent of KL Dra, and 2003aw. The variability selection of SDSS J2047+0008 from the 300 deg2 of SDSS Stripe 82 presages further AM CVn discoveries in future deep, multicolor, and time-domain surveys such as the Large Synoptic Survey Telescope (LSST). The new additions bring the total SDSS yield to seven AM CVns thus far, a substantial contribution to this rare subclass, versus the dozen previously known. Includes optical observations obtained with the Sloan Digital Sky Survey I and II and the Apache Point Observatory (APO) 3.5 m telescope which is owned and operated by the Astrophysical Research Consortium (ARC), and the WIYN Observatory which is a joint facility of the University of Wisconsin, Indiana University, Yale University, and NOAO.

A Search for Low Surface Brightness Galaxies in the Ultraviolet with GALEX

NASA Astrophysics Data System (ADS)

Wyder, Ted K.; GALEX Science Team

2006-12-01

Low surface brightness (LSB) galaxies have traditionally been difficult to detect at visible wavelengths due to their low contrast with the night sky and their low numbers per deg2. We describe a new search for LSB galaxies using UV images from the Galaxy Evolution Explorer (GALEX) satellite. The images are from the GALEX Medium Imaging Survey targeting mainly areas of the sky within the Sloan Digital Sky Survey (SDSS) footprint. Due to the UV sky background at high Galactic latitudes reaching levels of only approximately 28 mag arcsec-2 as well as the relatively large sky coverage from GALEX, we can potentially search for LSB galaxies that would be difficult to detect optically.After first convolving the images with a suitable kernel, we select a diameter limited set of objects which we then inspect manually in order to remove image artifacts and other spurious detections. Red galaxies that have high optical surface brightness can be identified using either the ratio of far-UV to near-UV flux or via comparison to SDSS images. We quantify our selection limits using a set of artificial galaxy tests. Our goal is to find blue, ultra-LSB galaxies that would be virtually undetectable in large optical imaging surveys. GALEX is a NASA Small Explorer, launched in April 2003. We gratefully acknowledge NASA's support for construction, operation, and science analysis for the GALEX mission.

Recent Local and State Action in Arizona to Maintain Sky Quality

NASA Astrophysics Data System (ADS)

Hall, Jeffrey C.; Shankland, P. D.; Green, R. F.; Jannuzi, B.

2014-01-01

The large number of observatories in Arizona has led to the development of a number of lighting control ordinances around the state, some quite strict. Several factors are now contributing to an increased need for active effort at the local, County, and State levels in maintaining the quality of these codes; these factors include an expansion of competing interests in the state, the increasing use of LED lighting, and the potential for major new investments through projects such as the Cherenkov Telescope Array (CTA) and enhancements to the Navy Precision Optical Interferometer. I will review recent strategies Arizona's observatories have used to effect maintenance of ordinances and preserve sky quality; cases include (1) a statewide effort in 2012 to curb a proliferation of electronic billboards and (2) engagement of a broad group of local, County, and State officials, as well as individuals from the private sector, in support of projects like CTA, including awareness of and support for dark-sky preservation.

Zonal drift velocities of the ionospheric plasma bubbles over brazilian region using oi630nm airglow digital images

NASA Astrophysics Data System (ADS)

Arruda, D. C. S.; Sobral, J. H. A.; Abdu, M. A.; Castilho, V. M.; Takahashi, H.

The zonal drift velocities of the ionospheric plasma bubbles over the Brazilian region are analyzed in this study that is based on OI630nm airglow digital images. These digital images were obtained by an all-sky imager system between October 1998 and August 2000, at Cachoeira Paulista (22.5°S, 45°W), a low latitude region. In this period, 138 nights of OI 630 nm airglow experiments were carried out of which 30 nights detected the ionospheric plasma bubbles. These 30 nights correspond to magnetically quiet days (ΣK_P<24+) and were grouped according approximately to their season. KEY WORDS: Imager System, Ionospheric Plasma Bubbles, Zonal drift velocities, OI630nm.

The History of the CONCAM Project: All Sky Monitors in the Digital Age

NASA Astrophysics Data System (ADS)

Nemiroff, Robert; Shamir, Lior; Pereira, Wellesley

2018-01-01

The CONtinuous CAMera (CONCAM) project, which ran from 2000 to (about) 2008, consisted of real-time, Internet-connected, fisheye cameras located at major astronomical observatories. At its peak, eleven CONCAMs around the globe monitored most of the night sky, most of the time. Initially designed to search for transients and stellar variability, CONCAMs gained initial notoriety as cloud monitors. As such, CONCAMs made -- and its successors continue to make -- ground-based astronomy more efficient. The original, compact, fisheye-observatory-in-a-suitcase design underwent several iterations, starting with CONCAM0 and with the last version dubbed CONCAM3. Although the CONCAM project itself concluded after centralized funding diminished, today more locally-operated, commercially-designed, CONCAM-like devices operate than ever before. It has even been shown that modern smartphones can operate in a CONCAM-like mode. It is speculated that the re-instatement of better global coordination of current wide-angle sky monitors could lead to better variability monitoring of the brightest stars and transients.

Seeing Beyond the Naked Eye in a Planetarium

NASA Astrophysics Data System (ADS)

Fairall, A.

2005-12-01

I have a philosophy that the traditional naked-eye sky, as usually shown in planetariums, should only be an introductory step in portraying the Universe. Consequently, over the years I have produced 'inter alia' various versions of an enhanced Milky Way (the latest based on Axel Mellenger's panorama), the extragalactic sky and the radio sky for projection on planetarium domes. I also put together a three-dimensional planetarium show-the audience being equipped with ChromDepth(tm) spectacles- which stepped from the Solar System to the cosmic microwave background. The advent of digital technology now makes all this much easier. Currently, Labyrinth, a visualization program developed in-house, serves much the same function as the Hayden Planetarium's Partiview, but also permits rendering and fl y-throughs of large-scale structures. It allows viewers to explore local cosmography. Labyrinth can produce images that operate with the 3-D spectacles; we have also produced a version of Partiview that does the same.

The Moon as a Tiny Bright Disc: Insights From Observations in the Planetarium.

PubMed

Carbon, Claus-Christian

2015-01-01

Despite a relatively constant visual angle, the size of the moon appears very variable, mostly depending on elevation and context factors--the so-called moon illusion. As our perceptual experience of the size of the moon is clearly limited to the perceptual sphere of the sky, however, we do not know whether the typical perception of the moon at its zenith reflects a veridical interpretation of its visual angle of only 0.5 degrees. When testing the moon illusion in a large-scale planetarium, we observed two important things: (a) variation in perceptual size was no longer apparent, and (b) the moon looked very much smaller than in any viewing condition in the real sky--even when comparing it at its zenith. A closer inspection of the control console of the planetarium revealed that classic-analog as well as updated-digital planetariums use projections of the moon with strongly increased sizes to compensate for the loss of a natural view of the moon in the artificial dome of the sky.

Dark Sky Collaborators: Arizona (AZ) Observatories, Communities, and Businesses

NASA Astrophysics Data System (ADS)

Del Castillo, Elizabeth Alvarez; Corbally, Christopher; Falco, Emilio E.; Green, Richard F.; Hall, Jeffrey C.; Williams, G. Grant

2015-03-01

With outdoor lighting ordinances in Arizona first in place around observatories in 1958 and 1972, then throughout the state since 1986, Arizonans have extensive experience working with communities and businesses to preserve our dark skies. Though communities are committed to the astronomy sector in our state, astronomers must collaborate with other stakeholders to implement solutions. Ongoing education and public outreach is necessary to enable ordinance updates as technology changes. Despite significant population increases, sky brightness measurements over the last 20 years show that ordinance updates are worth our efforts as we seek to maintain high quality skies around our observatories. Collaborations are being forged and actions taken to promote astronomy for the longer term in Arizona.

Identification of stars and digital version of the catalogue of 1958 by Brodskaya and Shajn

NASA Astrophysics Data System (ADS)

Gorbunov, M. A.; Shlyapnikov, A. A.

2017-12-01

The following topics are considered: the identification of objects on search maps, the determination of their coordinates at the epoch of 2000, and converting the published version of the catalogue of 1958 by Brodskaya and Shajn into a machine-readable format. The statistics for photometric and spectral data from the original catalogue is presented. A digital version of the catalogue is described, as well as its presentation in HTML, VOTable and AJS formats and the basic principles of work in the interactive application of International Virtual Observatory - the Aladin Sky Atlas.

Dark Clouds and Deadly Skies: Assessing the Strategic Effectiveness of Using Remotely Piloted Aircraft Outside of Designated Combat Zones

DTIC Science & Technology

2015-06-01

embassy bombings in Kenya and Tanzania that killed 225 people. An Islamist spokesman claimed that many nomadic tribesmen, including children, were...remained in the single digits . In September of 2011, Press TV, which is an Iranian news organization, claimed that there had been over 80 drone strikes

SDSS Masterclass

Science.gov Websites

systems puts your robotics skills to the test. Questions: Contact Carol Angarola, 630-840-3929 or canga the Sloan Digital Sky Survey make a comprehensive map of the Universe. The Galaxy Zoo we created is a measure their properties to help researchers around the world understand what makes galaxies tick. Robots

A Hot White Dwarf Luminosity Function from the Sloan Digital Sky Survey

DTIC Science & Technology

2009-01-01

Berro, E., Torres, S., & Catalan, S. 2008, ApJ, 682, L109 Ivezic, Z., Lupton, R. H., Schlegel, D., et al. 2004, Astron. Nachrichten , 325, 583...et al. 2002, AJ, 123, 485 Tucker, D., Kent, S., Richmond, M. W., et al. 2006, Astron. Nachrichten , 327, 821 Vennes, S. 1999, ApJ, 525, 995 Vennes, S

A Detailed Model Atmosphere Analysis of Cool White Dwarfs in the Sloan Digital Sky Survey

DTIC Science & Technology

2010-09-01

Road, Flagstaff, AZ 86001, USA 6 Department of Astronomy, 1 University Station C1400, Austin, TX 78712, USA 7 Kavli Institute for Cosmological Physics...with the Leggett et al. (1998) result, but the lack of infrared photometry prevented Harris et al. (2006) from a definite conclusion about the implied

Galaxy Zoo: Exploring the Motivations of Citizen Science Volunteers

ERIC Educational Resources Information Center

Raddick, M. Jordan; Bracey, Georgia; Gay, Pamela L.; Lintott, Chris J.; Murray, Phil; Schawinski, Kevin; Szalay, Alexander S.; Vandenberg, Jan

2010-01-01

The Galaxy Zoo citizen science website invites anyone with an Internet connection to participate in research by classifying galaxies from the Sloan Digital Sky Survey. As of April 2009, more than 200,000 volunteers have made more than 100 million galaxy classifications. In this article, we present results of a pilot study into the motivations and…

Evolution of the Air Toxics under the Big Sky Program

ERIC Educational Resources Information Center

Marra, Nancy; Vanek, Diana; Hester, Carolyn; Holian, Andrij; Ward, Tony; Adams, Earle; Knuth, Randy

2011-01-01

As a yearlong exploration of air quality and its relation to respiratory health, the "Air Toxics Under the Big Sky" program offers opportunities for students to learn and apply science process skills through self-designed inquiry-based research projects conducted within their communities. The program follows a systematic scope and sequence…

Solar Resource Assessment with Sky Imagery and a Virtual Testbed for Sky Imager Solar Forecasting

NASA Astrophysics Data System (ADS)

Kurtz, Benjamin Bernard

In recent years, ground-based sky imagers have emerged as a promising tool for forecasting solar energy on short time scales (0 to 30 minutes ahead). Following the development of sky imager hardware and algorithms at UC San Diego, we present three new or improved algorithms for sky imager forecasting and forecast evaluation. First, we present an algorithm for measuring irradiance with a sky imager. Sky imager forecasts are often used in conjunction with other instruments for measuring irradiance, so this has the potential to decrease instrumentation costs and logistical complexity. In particular, the forecast algorithm itself often relies on knowledge of the current irradiance which can now be provided directly from the sky images. Irradiance measurements are accurate to within about 10%. Second, we demonstrate a virtual sky imager testbed that can be used for validating and enhancing the forecast algorithm. The testbed uses high-quality (but slow) simulations to produce virtual clouds and sky images. Because virtual cloud locations are known, much more advanced validation procedures are possible with the virtual testbed than with measured data. In this way, we are able to determine that camera geometry and non-uniform evolution of the cloud field are the two largest sources of forecast error. Finally, with the assistance of the virtual sky imager testbed, we develop improvements to the cloud advection model used for forecasting. The new advection schemes are 10-20% better at short time horizons.

Affordable Digital Planetariums with WorldWide Telescope

NASA Astrophysics Data System (ADS)

Rosenfield, P.; Connolly, A.; Fay, J.; Sayres, C.; Tofflemire, B.

2011-09-01

Digital planetariums can provide a broader range of educational experiences than the more classical planetariums that use star-balls. This is because of their ability to project images, content from current research, and the 3-D distribution of the stars and galaxies. While there are hundreds of planetariums in the country, the reason that few of these are fully digital is the cost. In collaboration with Microsoft Research (MSR), we have developed a way to digitize existing planetariums for approximately $40,000 using freely available software. We describe here how off the shelf equipment, together with a WorldWide Telescope client, can provide a rich and truly interactive experience. This will enable students and the public to pan though multi-wavelength full-sky scientific data sets, explore 3-D visualizations of our Solar System (including trajectories of millions of minor planets), near-by stars, and the SDSS galaxy catalog.

Aerosol Properties Derived from Airborne Sky Radiance and Direct Beam Measurements in Recent NASA and DoE Field Campaigns

NASA Technical Reports Server (NTRS)

Redemann, J.; Flynn, C. J.; Shinozuka, Y.; Russell, P. B.; Kacenelenbogen, M.; Segal-Rosenheimer, M.; Livingston, J. M.; Schmid, B.; Dunagan, S. E.; Johnson, R. R.;

Generation of complete source samples from the Slew Survey

NASA Technical Reports Server (NTRS)

Schachter, Jonathan

1992-01-01

The Einstein Slew Survey consists of 819 bright X-ray sources, of which 636 (or 78 percent) are identified with counterparts in standard catalogs. We argue for the importance of bright X-ray surveys, and compare the slew results to the ROSAT all-sky survey. Also, we discuss statistical techniques for minimizing confusion in arcminute error circles in digitized data. We describe the 238 Slew Survey AGN, clusters, and BL Lac objects identified to date and their implications for logN-logS and source evolution studies. Also given is a catalog of 1075 sources detected in the Einstein Imaging Proportional Counter (IPC) Slew Survey of the X-ray sky. Five hundred fifty-four of these sources were not previously known as X-ray sources.

Mapping the Heavens: Probing Cosmology with Large Surveys

ScienceCinema

Frieman, Joshua [Fermilab

2017-12-09

This talk will provide an overview of recent and on-going sky surveys, focusing on their implications for cosmology. I will place particular emphasis on the Sloan Digital Sky Survey, the most ambitious mapping of the Universe yet undertaken, showing a virtual fly-through of the survey that reveals the large-scale structure of the galaxy distribution. Recent measurements of this large-scale structure, in combination with observations of the cosmic microwave background, have provided independent evidence for a Universe dominated by dark matter and dark energy as well as insights into how galaxies and larger-scale structures formed. Future planned surveys will build on these foundations to probe the history of the cosmic expansion--and thereby the dark energy--with greater precision.

A SURVEY FOR NEW MEMBERS OF THE TAURUS STAR-FORMING REGION WITH THE SLOAN DIGITAL SKY SURVEY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Luhman, K. L.; Mamajek, E. E.; Shukla, S. J.

Previous studies have found that ∼1 deg{sup 2} fields surrounding the stellar aggregates in the Taurus star-forming region exhibit a surplus of solar-mass stars relative to denser clusters like IC 348 and the Orion Nebula Cluster. To test whether this difference reflects mass segregation in Taurus or a variation in the initial mass function, we have performed a survey for members of Taurus across a large field (∼40 deg{sup 2}) that was imaged by the Sloan Digital Sky Survey (SDSS). We obtained optical and near-infrared spectra of candidate members identified with those images and the Two Micron All Sky Survey, as wellmore » as miscellaneous candidates that were selected with several other diagnostics of membership. We have classified 22 of the candidates as new members of Taurus, which includes one of the coolest known members (M9.75). Our updated census of members within the SDSS field shows a surplus of solar-mass stars relative to clusters, although it is less pronounced than in the smaller fields toward the stellar aggregates that were surveyed for previously measured mass functions in Taurus. In addition to spectra of our new members, we include in our study near-IR spectra of roughly half of the known members of Taurus, which are used to refine their spectral types and extinctions. We also present an updated set of near-IR standard spectra for classifying young stars and brown dwarfs at M and L types.« less

Goals and strategies in the global control design of the OAJ Robotic Observatory

NASA Astrophysics Data System (ADS)

Yanes-Díaz, A.; Rueda-Teruel, S.; Antón, J. L.; Rueda-Teruel, F.; Moles, M.; Cenarro, A. J.; Marín-Franch, A.; Ederoclite, A.; Gruel, N.; Varela, J.; Cristóbal-Hornillos, D.; Chueca, S.; Díaz-Martín, M. C.; Guillén, L.; Luis-Simoes, R.; Maícas, N.; Lamadrid, J. L.; López-Sainz, A.; Hernández-Fuertes, J.; Valdivielso, L.; Mendes de Oliveira, C.; Penteado, P.; Schoenell, W.; Kanaan, A.

2012-09-01

There are many ways to solve the challenging problem of making a high performance robotic observatory from scratch. The Observatorio Astrofísico de Javalambre (OAJ) is a new astronomical facility located in the Sierra de Javalambre (Teruel, Spain) whose primary role will be to conduct all-sky astronomical surveys. The OAJ control system has been designed from a global point of view including astronomical subsystems as well as infrastructures and other facilities. Three main factors have been considered in the design of a global control system for the robotic OAJ: quality, reliability and efficiency. We propose CIA (Control Integrated Architecture) design and OEE (Overall Equipment Effectiveness) as a key performance indicator in order to improve operation processes, minimizing resources and obtaining high cost reduction whilst maintaining quality requirements. The OAJ subsystems considered for the control integrated architecture are the following: two wide-field telescopes and their instrumentation, active optics subsystems, facilities for sky quality monitoring (seeing, extinction, sky background, sky brightness, cloud distribution, meteorological station), domes and several infrastructure facilities such as water supply, glycol water, water treatment plant, air conditioning, compressed air, LN2 plant, illumination, surveillance, access control, fire suppression, electrical generators, electrical distribution, electrical consumption, communication network, Uninterruptible Power Supply and two main control rooms, one at the OAJ and the other remotely located in Teruel, 40km from the observatory, connected through a microwave radio-link. This paper presents the OAJ strategy in control design to achieve maximum quality efficiency for the observatory processes and operations, giving practical examples of our approach.

The Impact of Assimilation of GPM Clear Sky Radiance on HWRF Hurricane Track and Intensity Forecasts

NASA Astrophysics Data System (ADS)

Yu, C. L.; Pu, Z.

2016-12-01

The impact of GPM microwave imager (GMI) clear sky radiances on hurricane forecasting is examined by ingesting GMI level 1C recalibrated brightness temperature into the NCEP Gridpoint Statistical Interpolation (GSI)- based ensemble-variational hybrid data assimilation system for the operational Hurricane Weather Research and Forecast (HWRF) system. The GMI clear sky radiances are compared with the Community Radiative Transfer Model (CRTM) simulated radiances to closely study the quality of the radiance observations. The quality check result indicates the presence of bias in various channels. A static bias correction scheme, in which the appropriate bias correction coefficients for GMI data is evaluated by applying regression method on a sufficiently large sample of data representative to the observational bias in the regions of concern, is used to correct the observational bias in GMI clear sky radiances. Forecast results with and without assimilation of GMI radiance are compared using hurricane cases from recent hurricane seasons (e.g., Hurricane Joaquin in 2015). Diagnoses of data assimilation results show that the bias correction coefficients obtained from the regression method can correct the inherent biases in GMI radiance data, significantly reducing observational residuals. The removal of biases also allows more data to pass GSI quality control and hence to be assimilated into the model. Forecast results for hurricane Joaquin demonstrates that the quality of analysis from the data assimilation is sensitive to the bias correction, with positive impacts on the hurricane track forecast when systematic biases are removed from the radiance data. Details will be presented at the symposium.

Cool White Dwarfs Found in the UKIRT Infrared Deep Sky Survey

NASA Astrophysics Data System (ADS)

Leggett, S. K.; Lodieu, N.; Tremblay, P.-E.; Bergeron, P.; Nitta, A.

2011-07-01

We present the results of a search for cool white dwarfs in the United Kingdom InfraRed Telescope (UKIRT) Infrared Deep Sky Survey (UKIDSS) Large Area Survey (LAS). The UKIDSS LAS photometry was paired with the Sloan Digital Sky Survey to identify cool hydrogen-rich white dwarf candidates by their neutral optical colors and blue near-infrared colors, as well as faint reduced proper motion magnitudes. Optical spectroscopy was obtained at Gemini Observatory and showed the majority of the candidates to be newly identified cool degenerates, with a small number of G- to K-type (sub)dwarf contaminants. Our initial search of 280 deg2 of sky resulted in seven new white dwarfs with effective temperature T eff ≈ 6000 K. The current follow-up of 1400 deg2 of sky has produced 13 new white dwarfs. Model fits to the photometry show that seven of the newly identified white dwarfs have 4120 K <=T eff <= 4480 K, and cooling ages between 7.3 Gyr and 8.7 Gyr; they have 40 km s-1 <= v tan <= 85 km s-1 and are likely to be thick disk 10-11 Gyr-old objects. The other half of the sample has 4610 K <=T eff <= 5260 K, cooling ages between 4.3 Gyr and 6.9 Gyr, and 60 km s-1 <= v tan <= 100 km s-1. These are either thin disk remnants with unusually high velocities, or lower-mass remnants of thick disk or halo late-F or G stars.

The Citizen-Scientist as Data Collector: GLOBE at Night, Part 2

NASA Astrophysics Data System (ADS)

Walker, C. E.; Pompea, S. M.; Ward, D.; Henderson, S.; Meymaris, K.; Gallagher, S.; Salisbury, D.

2006-12-01

An innovative program to realize light pollution education on two continents via Internet 2-based videoconferencing was begun 4 years ago by the National Optical Astronomy Observatory. Bilingual science teachers and their students in Arizona and Chile recorded the brightness of the night sky by matching its appearance toward the constellation Orion with one of 6 stellar maps of limiting magnitude. Students from both hemispheres would report their findings via videoconferences. In the last year the program has evolved in collaboration with UCAR and other partners into an international, user-friendly, web-based science event open to anyone in the world, known as GLOBE at Night. GLOBE at Night uses the same design to observe and record the visible stars toward Orion, as a means of measuring light pollution in a given location. The inaugural event occurred over 11 nights last March, when 18,000 citizen- scientists made over 4,500 observations from 96 countries. Analysis of the GLOBE at Night data set found that the brighter skies corresponded to areas with higher population density, and that most observations were taken in a location with some light pollution. The data also tended to confirm that satellite data is reliable in assessing light pollution. This session will describe our program to incorporate more technology into the GLOBE at Night program. Citizen-scientists will use sky quality meters (visible light photometers), calibrated digital photography, and GPS as a means to measure and map more accurately the brightness of the sky at selected urban and rural sites. This extension of the program is designed to aid further in teaching about the impact of artificial lighting on local environments and the ongoing loss of a dark night sky as a natural resource. We will also describe how detailed maps of selected urban areas can be used to assess lighting design, safety considerations and energy usage. Given the widespread interest in the inaugural GLOBE at Night event, the GLOBE at Night team is eager to offer it again from March 8-21, 2007. For more information, see www.globe.gov/GaN or contact globeatnight@globe.gov or outreach@noao.edu. GLOBE at Night is a collaboration between The GLOBE Program, the National Optical Astronomy Observatory (NOAO), Centro de Apoyo a la Didactica de la Astronomia (CADIAS), Windows to the Universe, and Environmental Systems Research Institute, Inc. (ESRI). NOAO is operated by the Association of Universities for Research in Astronomy (AURA), Inc. under cooperative agreement with the National Science Foundation.

Modeling The Atmosphere In The Era Of Big Data From Extremely Wide Field-Of-View Telescopes

NASA Astrophysics Data System (ADS)

Gonzalez Quiles, Junellie; Nordin, Jakob

2018-01-01

Surveys like the Sloan Digital Sky Survey (SDSS), Pan-STARRS and the Palomar Transient Factory Survey (PTF) receive large amounts of data, which need to be processed and calibrated in order to correct for various factors. One of the limiting factors in obtaining high quality data is the atmosphere, and it is therefore essential to find the appropriate calibration for the atmospheric extinction. It is to be expected that a physical atmospheric model, compared to a photometric calibration used currently by PTF, is more effective in calibrating for the atmospheric extinction due to its ability to account for rapid atmospheric fluctuation and objects of different colors. We focused on creating tools to model the atmospheric extinction for the upcoming Zwicky Transient Factory Survey (ZTF). In order to model the atmosphere, we created a program that combines input data and catalogue values, and efficiently handles them. Then, using PTF data and the SDSS catalogue, we created several models to fit the data, and tested the quality of the fits by chi-square minimization. This will allow us to optimize atmospheric extinction for the upcoming ZTF in the near future.

unWISE: Unblurred Coadds of the WISE Imaging

NASA Astrophysics Data System (ADS)

Lang, Dustin

2014-05-01

The Wide-field Infrared Survey Explorer (WISE) satellite observed the full sky in four mid-infrared bands in the 2.8-28 μm range. The primary mission was completed in 2010. The WISE team has done a superb job of producing a series of high-quality, well-documented, complete data releases in a timely manner. However, the "Atlas Image" coadds that are part of the recent AllWISE and previous data releases were intentionally blurred. Convolving the images by the point-spread function while coadding results in "matched-filtered" images that are close to optimal for detecting isolated point sources. But these matched-filtered images are sub-optimal or inappropriate for other purposes. For example, we are photometering the WISE images at the locations of sources detected in the Sloan Digital Sky Survey through forward modeling, and this blurring decreases the available signal-to-noise by effectively broadening the point-spread function. This paper presents a new set of coadds of the WISE images that have not been blurred. These images retain the intrinsic resolution of the data and are appropriate for photometry preserving the available signal-to-noise. Users should be cautioned, however, that the W3- and W4-band coadds contain artifacts around large, bright structures (large galaxies, dusty nebulae, etc.); eliminating these artifacts is the subject of ongoing work. These new coadds, and the code used to produce them, are publicly available at http://unwise.me.

Introducing the Virtual Astronomy Multimedia Project

NASA Astrophysics Data System (ADS)

Wyatt, Ryan; Christensen, L. L.; Gauthier, A.; Hurt, R.

2008-05-01

The goal of the Virtual Astronomy Multimedia Project (VAMP) is to promote and vastly multiply the use of astronomy multimedia resources—from images and illustrations to animations, movies, and podcasts—and enable innovative future exploitation of a wide variety of outreach media by systematically linking resource archives worldwide. High-quality astronomical images, accompanied by rich caption and background information, abound on the web and yet prove notoriously difficult to locate efficiently using existing search tools. The Virtual Astronomy Multimedia Project offers a solution via the Astronomy Visualization Metadata (AVM) standard. Due to roll out in time for IYA2009, VAMP manages the design, implementation, and dissemination of the AVM standard for the education and public outreach astronomical imagery that observatories publish. VAMP will support implementations in World Wide Telescope, Google Sky, Portal to the Universe, and 365 Days of Astronomy, as well as Uniview and DigitalSky software designed specifically for planetariums. The VAMP workshop will introduce the AVM standard and describe its features, highlighting sample image tagging processes using diverse tools—the critical first step in getting media into VAMP. Participants with laptops will have an opportunity to experiment first hand, and workshop organizers will update a web page with system requirements and software options in advance of the conference (see http://virtualastronomy.org/ASP2008/ for links to resources). The workshop will also engage participants in a discussion and review of the innovative AVM image hierarchy taxonomy, which will soon be extended to other types of media.

Using machine learning techniques to automate sky survey catalog generation

NASA Technical Reports Server (NTRS)

Fayyad, Usama M.; Roden, J. C.; Doyle, R. J.; Weir, Nicholas; Djorgovski, S. G.

1993-01-01

We describe the application of machine classification techniques to the development of an automated tool for the reduction of a large scientific data set. The 2nd Palomar Observatory Sky Survey provides comprehensive photographic coverage of the northern celestial hemisphere. The photographic plates are being digitized into images containing on the order of 10(exp 7) galaxies and 10(exp 8) stars. Since the size of this data set precludes manual analysis and classification of objects, our approach is to develop a software system which integrates independently developed techniques for image processing and data classification. Image processing routines are applied to identify and measure features of sky objects. Selected features are used to determine the classification of each object. GID3* and O-BTree, two inductive learning techniques, are used to automatically learn classification decision trees from examples. We describe the techniques used, the details of our specific application, and the initial encouraging results which indicate that our approach is well-suited to the problem. The benefits of the approach are increased data reduction throughput, consistency of classification, and the automated derivation of classification rules that will form an objective, examinable basis for classifying sky objects. Furthermore, astronomers will be freed from the tedium of an intensely visual task to pursue more challenging analysis and interpretation problems given automatically cataloged data.

Characterization of Light at Night Data from Select SkyGlowNet Nodes

NASA Astrophysics Data System (ADS)

Flurchick, K. M.; Deal, S.; Foster, C.

2013-05-01

Internet-enabled sky brightness meters (iSBMs) that continuously record and log sky brightness at the zenith have been installed at the prototype nodes of a network called SkyGlowNet. Also logged are time and weather information. These data are polled at a user-defined frequency, typically about every 45 seconds. Although the SkyGlowNetdata are used for various professional scientific studies, they are also useful for independent student research projects. In this case, the data are uploaded to the SkyGlowNetwebsite, initially to a proprietary area where the data for each institution are embargoed for one or two semesters as students conduct research projects with their data. When released from embargo, the data are moved to another area where they can be accessed by all SkyGlowNet participants. In this paper, we describe a student project in which the data collected at two SkyGlowNet sites are characterized. The data streams are parsed into homogenous segments and statistical tools are employed to describe variations observed in the data values. We demonstrate how to differentiate between natural phenomena and the effects of artificial lighting on the brightness of the night sky. In our poster we show how these effects compare between sites as separate as Arizona and North Carolina. We also have experimented with the development of statistical metrics that are used to help categorize sky brightness on select nights, and can nearly automatically provide a characterization of the quality of the night sky for astronomical purposes.

Accuracy and precision of two indirect methods for estimating canopy fuels

Treesearch

Abran Steele-Feldman; Elizabeth Reinhardt; Russell A. Parsons

2006-01-01

We compared the accuracy and precision of digital hemispherical photography and the LI-COR LAI-2000 plant canopy analyzer as predictors of canopy fuels. We collected data on 12 plots in western Montana under a variety of lighting and sky conditions, and used a variety of processing methods to compute estimates. Repeated measurements from each method displayed...

A quantitative topographic analysis of the Sky Islands: a closer examination of the topography-biodiversity relationship in the Madrean Archipelago

Treesearch

David Coblentz; Kurt H. Riitters

2005-01-01

The relationship between topography and biodiversity is well documented in the Madrean Archipelago. However, despite this recognition, most biogeographical studies concerning the role of topography have relied primarily on a qualitative description of the landscape. Using an algorithm that operates on a high-resolution digital elevation model we present a quantitative...

Nebula observations. Catalogues and archive of photoplates

NASA Astrophysics Data System (ADS)

Shlyapnikov, A. A.; Smirnova, M. A.; Elizarova, N. V.

2017-12-01

A process of data systematization based on "Academician G.A. Shajn's Plan" for studying the Galaxy structure related to nebula observations is considered. The creation of digital versions of catalogues of observations and publications is described, as well as their presentation in HTML, VOTable and AJS formats and basic principles of work in the interactive application of International Virtual Observatory the Aladin Sky Atlas.

Understanding Product Attachment and Expected Product Lifetime by Extending Technology Acceptance Model (TAM) with Product Personalization and Innovation Diffusion Theory (IDT)

ERIC Educational Resources Information Center

Yun, Younghwa

2013-01-01

Identifying and understanding consumers is fundamental, especially for quickly spreading new products. In recent years, the popularity of digital gadgets has sky rocketed; however, there has also been a growing tendency of relative obsolescence--replacement of a product regardless of the demise of its perfect functioning. Therefore, a question is…

The Sixth Data Release of the Sloan Digital Sky Survey

DTIC Science & Technology

2008-04-01

Jurek Krzesinski,6,48 Nikolay Kuropatkin,1 Donald Q. Lamb,25,46 Hubert Lampeitl,29 Svetlana Lebedeva,1 Young Sun Lee,15 R. French Leger,1 Sébastien...Lépine,49 Marcos Lima,27,26 Huan Lin,1 Daniel C. Long,6 Craig P. Loomis,9 Jon Loveday,50 Robert H. Lupton,9 Olena Malanushenko,6 Viktor Malanushenko,6

The Moon and Mars in August

NASA Astrophysics Data System (ADS)

Paice, P.

2003-10-01

The naked-eye view of the full Moon and Mars together was captured by Peter Paice, Belfast, on 2003 August 12/13 at midnight UT using an Olympus 730 Ultra Zoom digital camera, with no additional processing applied. In a partly cloudy sky, the secret was to wait until clouds partly occluded the power of the Moon, and Mars was in a clear patch.

An Interpretive Study of Meanings Citizen Scientists Make When Participating in Galaxy Zoo

ERIC Educational Resources Information Center

Mankowski, Trent A.; Slater, Stephanie J.; Slater, Timothy F.

2011-01-01

A particularly successful effort to engage the public in science has been to move the nearly countless galaxies imaged by the Sloan Digital Sky Survey to citizen scientists in a project known widely as Galaxy Zoo (URL; http://www.galaxyzoo.org). By examining the motivations, methods and appeal of Galaxy Zoo to the participating public, other…

The Sloan Digital Sky Survey Reverberation Mapping Project: The C IV Blueshift, Its Variability, and Its Dependence Upon Quasar Properties

NASA Astrophysics Data System (ADS)

Sun, Mouyuan; Xue, Yongquan; Richards, Gordon T.; Trump, Jonathan R.; Shen, Yue; Brandt, W. N.; Schneider, D. P.

2018-02-01

We use the multi-epoch spectra of 362 quasars from the Sloan Digital Sky Survey Reverberation Mapping project to investigate the dependence of the blueshift of C IV relative to Mg II on quasar properties. We confirm that high-blueshift sources tend to have low C IV equivalent widths (EWs), and that the low-EW sources span a range of blueshift. Other high-ionization lines, such as He II, also show similar blueshift properties. The ratio of the line width (measured as both the full width at half maximum and the velocity dispersion) of C IV to that of Mg II increases with blueshift. Quasar variability enhances the connection between the C IV blueshift and quasar properties (e.g., EW). The variability of the Mg II line center (i.e., the wavelength that bisects the cumulative line flux) increases with blueshift. In contrast, the C IV line center shows weaker variability at the extreme blueshifts. Quasars with the high-blueshift C IV lines tend to have less variable continuum emission, when controlling for EW, luminosity, and redshift. Our results support the scenario that high-blueshift sources tend to have large Eddington ratios.

RELATIVE ORIENTATION OF PAIRS OF SPIRAL GALAXIES IN THE SLOAN DIGITAL SKY SURVEY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Buxton, Jesse; Ryden, Barbara S., E-mail: buxton.45@osu.edu, E-mail: ryden@astronomy.ohio-state.edu

2012-09-10

From our study of binary spiral galaxies in the Sloan Digital Sky Survey Data Release 6, we find that the relative orientation of disks in binary spiral galaxies is consistent with their being drawn from a random distribution of orientations. For 747 isolated pairs of luminous disk galaxies, the distribution of {phi}, the angle between the major axes of the galaxy images, is consistent with a uniform distribution on the interval [0 Degree-Sign , 90 Degree-Sign ]. With the assumption that the disk galaxies are oblate spheroids, we can compute cos {beta}, where {beta} is the angle between the rotationmore » axes of the disks. In the case that one galaxy in the binary is face-on or edge-on, the tilt ambiguity is resolved, and cos {beta} can be computed unambiguously. For 94 isolated pairs with at least one face-on member, and for 171 isolated pairs with at least one edge-on member, the distribution of cos {beta} is statistically consistent with the distribution of cos i for isolated disk galaxies. This result is consistent with random orientations of the disks within pairs.« less

Red Misfits in the Sloan Digital Sky Survey: properties of star-forming red galaxies

NASA Astrophysics Data System (ADS)

Evans, Fraser A.; Parker, Laura C.; Roberts, Ian D.

2018-06-01

We study Red Misfits, a population of red, star-forming galaxies in the local Universe. We classify galaxies based on inclination-corrected optical colours and specific star formation rates derived from the Sloan Digital Sky Survey Data Release 7. Although the majority of blue galaxies are star-forming and most red galaxies exhibit little to no ongoing star formation, a small but significant population of galaxies (˜11 per cent at all stellar masses) are classified as red in colour yet actively star-forming. We explore a number of properties of these galaxies and demonstrate that Red Misfits are not simply dusty or highly inclined blue cloud galaxies or quiescent red galaxies with poorly constrained star formation. The proportion of Red Misfits is nearly independent of environment, and this population exhibits both intermediate morphologies and an enhanced likelihood of hosting an active galactic nucleus. We conclude that Red Misfits are a transition population, gradually quenching on their way to the red sequence and this quenching is dominated by internal processes rather than environmentally driven processes. We discuss the connection between Red Misfits and other transition galaxy populations, namely S0s, red spirals, and green valley galaxies.

Learning to Work with Databases in Astronomy: Quantitative Analysis of Science Educators' and Students' Pre-/Post-Tests

NASA Astrophysics Data System (ADS)

Schwortz, Andria C.; Burrows, Andrea C.; Myers, Adam D.

2015-01-01

Astronomy is increasingly moving towards working with large databases, from the state-of-the-art Sloan Digital Sky Survey Data Release 10, to the historical Digital Access to a Sky Century at Harvard. Non-astronomy fields as well tend to work with large datasets, be it in the form of warehouse inventory, health trends, or the stock market. However very few fields explicitly teach students the necessary skills to analyze such data. The authors studied a matched set of 37 participants working with 200-entry databases in astronomy using Google Spreadsheets, with limited information about a random set of quasars drawn from SDSS DR5. Here the authors present the quantitative results from an eight question pre-/post-test, with questions designed to span Bloom's taxonomy, on both the topics of the skills of using spreadsheets, and the content of quasars. Participants included both Astro 101 summer students and professionals including in-service K-12 teachers and science communicators. All groups showed statistically significant gains (as per Hake, 1998), with the greatest difference between women's gains of 0.196 and men's of 0.480.

Ultracool dwarf benchmarks with Gaia primaries

NASA Astrophysics Data System (ADS)

Marocco, F.; Pinfield, D. J.; Cook, N. J.; Zapatero Osorio, M. R.; Montes, D.; Caballero, J. A.; Gálvez-Ortiz, M. C.; Gromadzki, M.; Jones, H. R. A.; Kurtev, R.; Smart, R. L.; Zhang, Z.; Cabrera Lavers, A. L.; García Álvarez, D.; Qi, Z. X.; Rickard, M. J.; Dover, L.

2017-10-01

We explore the potential of Gaia for the field of benchmark ultracool/brown dwarf companions, and present the results of an initial search for metal-rich/metal-poor systems. A simulated population of resolved ultracool dwarf companions to Gaia primary stars is generated and assessed. Of the order of ˜24 000 companions should be identifiable outside of the Galactic plane (|b| > 10 deg) with large-scale ground- and space-based surveys including late M, L, T and Y types. Our simulated companion parameter space covers 0.02 ≤ M/M⊙ ≤ 0.1, 0.1 ≤ age/Gyr ≤ 14 and -2.5 ≤ [Fe/H] ≤ 0.5, with systems required to have a false alarm probability <10-4, based on projected separation and expected constraints on common distance, common proper motion and/or common radial velocity. Within this bulk population, we identify smaller target subsets of rarer systems whose collective properties still span the full parameter space of the population, as well as systems containing primary stars that are good age calibrators. Our simulation analysis leads to a series of recommendations for candidate selection and observational follow-up that could identify ˜500 diverse Gaia benchmarks. As a test of the veracity of our methodology and simulations, our initial search uses UKIRT Infrared Deep Sky Survey and Sloan Digital Sky Survey to select secondaries, with the parameters of primaries taken from Tycho-2, Radial Velocity Experiment, Large sky Area Multi-Object fibre Spectroscopic Telescope and Tycho-Gaia Astrometric Solution. We identify and follow up 13 new benchmarks. These include M8-L2 companions, with metallicity constraints ranging in quality, but robust in the range -0.39 ≤ [Fe/H] ≤ +0.36, and with projected physical separation in the range 0.6 < s/kau < 76. Going forward, Gaia offers a very high yield of benchmark systems, from which diverse subsamples may be able to calibrate a range of foundational ultracool/sub-stellar theory and observation.

Synthesis of optical polarization signatures of military aircraft

NASA Astrophysics Data System (ADS)

Egan, Walter G.; Duggin, Michael J.

2002-01-01

Focal plane wide band IR imagery will be compared with visual wide band focal plane digital imagery of a camouflaged B-52 bomber. Extreme enhancement is possible using digital polarized imagery. The experimental observations will be compared to theoretical calculations and modeling result of both specular and shadowed areas to allow extrapolations to the synthesis of the optical polarization signatures of other aircraft. The relationship of both the specular and the shadowed areas to surface structure, orientation, specularlity, roughness, shadowing and the complex index of refraction will be illustrated. The imagery was obtained in two plane-polarized directions. Many aircraft locations were measured as well as sky background.

Scanning the Heavens

NASA Astrophysics Data System (ADS)

Hayes, Brian

1994-12-01

Gleaning further clues to the structure of the universe will require larger data samples. To that end, a major new survey of the skies called the Sloan Digital Star Survey (SDSS), is in preparation. It will catalog some 50 million galaxies and about 70 million stars. A new 2.5 meter telescope to be erected at Apache Point Observatory in New Mexico will be dedicated to the survey. The telescope is not the key innovation that will make the survey possible. The crucial factor is the technology for digitally recording large numbers of images and spectra and for automating the analysis, recognition, and classification of those images and spectra. The methods to be used are discussed.

A wideband, high-resolution spectrum analyzer

NASA Technical Reports Server (NTRS)

Quirk, M. P.; Wilck, H. C.; Garyantes, M. F.; Grimm, M. J.

1988-01-01

A two-million-channel, 40 MHz bandwidth, digital spectrum analyzer under development at the Jet Propulsion Laboratory is described. The analyzer system will serve as a prototype processor for the sky survey portion of NASA's Search for Extraterrestrial Intelligence program and for other applications in the Deep Space Network. The analyzer digitizes an analog input, performs a 2 (sup 21) point Discrete Fourier Transform, accumulates the output power, normalizes the output to remove frequency-dependent gain, and automates simple signal detection algorithms. Due to its built-in frequency-domain processing functions and configuration flexibility, the analyzer is a very powerful tool for real-time signal analysis.

A wide-band high-resolution spectrum analyzer

NASA Technical Reports Server (NTRS)

Quirk, Maureen P.; Garyantes, Michael F.; Wilck, Helmut C.; Grimm, Michael J.

1988-01-01

A two-million-channel, 40 MHz bandwidth, digital spectrum analyzer under development at the Jet Propulsion Laboratory is described. The analyzer system will serve as a prototype processor for the sky survey portion of NASA's Search for Extraterrestrial Intelligence program and for other applications in the Deep Space Network. The analyzer digitizes an analog input, performs a 2 (sup 21) point Discrete Fourier Transform, accumulates the output power, normalizes the output to remove frequency-dependent gain, and automates simple detection algorithms. Due to its built-in frequency-domain processing functions and configuration flexibility, the analyzer is a very powerful tool for real-time signal analysis.

A wide-band high-resolution spectrum analyzer.

PubMed

Quirk, M P; Garyantes, M F; Wilck, H C; Grimm, M J

1988-12-01

This paper describes a two-million-channel 40-MHz-bandwidth, digital spectrum analyzer under development at the Jet Propulsion Laboratory. The analyzer system will serve as a prototype processor for the sky survey portion of NASA's Search for Extraterrestrial Intelligence program and for other applications in the Deep Space Network. The analyzer digitizes an analog input, performs a 2(21)-point, Discrete Fourier Transform, accumulates the output power, normalizes the output to remove frequency-dependent gain, and automates simple signal detection algorithms. Due to its built-in frequency-domain processing functions and configuration flexibility, the analyzer is a very powerful tool for real-time signal analysis and detection.

Dark-Skies Awareness

NASA Astrophysics Data System (ADS)

Walker, Constance E.

2009-05-01

The arc of the Milky Way seen from a truly dark location is part of our planet's natural heritage. More than one fifth of the world population, two thirds of the United States population and one half of the European Union population have already lost naked eye visibility of the Milky Way. This loss, caused by light pollution, is a serious and growing issue that impacts astronomical research, the economy, ecology, energy conservation, human health, public safety and our shared ability to see the night sky. For this reason, "Dark Skies” is a cornerstone project of the International Year of Astronomy. Its goal is to raise public awareness of the impact of artificial lighting on local environments by getting people worldwide involved in a variety of programs that: 1. Teach about dark skies using new technology (e.g., an activity-based planetarium show on DVD, podcasting, social networking on Facebook and MySpace, a Second Life presence) 2. Provide thematic events on light pollution at star parties and observatory open houses (Dark Skies Discovery Sites, Nights in the (National) Parks, Sidewalk Astronomy) 3. Organize events in the arts (e.g., a photography contest) 4. Involve citizen-scientists in naked-eye and digital-meter star hunting programs (e.g., GLOBE at Night, "How Many Stars?", the Great World Wide Star Count and the radio frequency interference equivalent: "Quiet Skies") and 5. Raise awareness about the link between light pollution and public health, economic issues, ecological consequences, energy conservation, safety and security, and astronomy (e.g., The Starlight Initiative, World Night in Defense of Starlight, International Dark Sky Week, International Dark-Sky Communities, Earth Hour, The Great Switch Out, a traveling exhibit, downloadable posters and brochures). The presentation will provide an update, describe how people can become involved and take a look ahead at the program's sustainability. For more information, visit www.darkskiesawareness.org.

Dark Skies Awareness Programs for the International Year of Astronomy

NASA Astrophysics Data System (ADS)

Walker, Constance E.; US IYA Dark Skies Working Group

2009-05-01

The arc of the Milky Way seen from a truly dark location is part of our planet's cultural and natural heritage. More than 1/5 of the world population, 2/3 of the United States population and 1/2 of the European Union population have already lost naked-eye visibility of the Milky Way. This loss, caused by light pollution, is a serious and growing issue that impacts astronomical research, the economy, ecology, energy conservation, human health, public safety and our shared ability to see the night sky. For this reason, "Dark Skies” is a cornerstone project of the International Year of Astronomy. Its goal is to raise public awareness of the impact of artificial lighting on local environments by getting people worldwide involved in a variety of programs that: 1) Teach about dark skies using new technology (e.g., an activity-based planetarium show on DVD, podcasting, social networking on Facebook and MySpace, a Second Life presence) 2) Provide thematic events on light pollution at star parties and observatory open houses (Dark Skies Discovery Sites, Nights in the (National) Parks, Sidewalk Astronomy) 3) Organize events in the arts (e.g., a photography contest) 4) Involve citizen-scientists in naked-eye and digital-meter star hunting programs (e.g., GLOBE at Night, "How Many Stars?", the Great World Wide Star Count and the radio frequency interference equivalent: "Quiet Skies") and 5) Raise awareness about the link between light pollution and public health, economic issues, ecological consequences, energy conservation, safety and security, and astronomy (e.g., The Starlight Initiative, World Night in Defense of Starlight, International Dark Sky Week, International Dark-Sky Communities, Earth Hour, The Great Switch Out, a traveling exhibit, downloadable posters and brochures). The poster will provide an update, describe how people can continue to participate, and take a look ahead at the program's sustainability. For more information, visit www.darkskiesawareness.org.

Can You See the Stars? Citizen-Science Programs to Measure Night Sky Brightness

NASA Astrophysics Data System (ADS)

Walker, Constance E.

2009-05-01

For the IYA2009 Dark Skies Awareness Cornerstone Project, partners in dark-sky, astronomy and environmental education are promoting three citizen-scientist programs that measure light pollution at local levels worldwide. These programs take the form of "star hunts", providing people with fun and direct ways to acquire heightened awareness about light pollution through first-hand observations of the night sky. Together the programs are spanning the entire IYA, namely: GLOBE at Night in March, Great World Wide Star Count in October, and How Many Stars during the rest of the year. Citizen-scientists - students, educators, amateur astronomers and the general public - measure the darkness of their local skies and contribute observations online to a world map. Anyone anywhere anytime can look within particular constellations for the faintest stars and match them to one of seven star maps. For more precise measurements, digital sky-brightness meters can be used. Measurements, along with the measurement location, time, and date, are submitted online, and within a few days to weeks a world map showing results is available. These measurements can be compared with data from previous years, as well as with satellite data, population densities, and electrical power-usage maps. Measurements are available online via Google Earth or other tools and as downloadable datasets. Data from multiple locations in one city or region are especially interesting, and can be used as the basis of a class project or science fair experiment, or even to inform the development of public policy. In the last few years these programs successfully conducted campaigns in which more than 35,000 observations were submitted from over 100 countries. The presentation will provide an update, describe how people can become involved and take a look ahead at the program's sustainability. For further information about these and other Dark Skies Awareness programs, please visit www.darkskiesawareness.org.

Stellar and planetary remnants in digital sky surveys

NASA Astrophysics Data System (ADS)

Girven, Jonathan

Large scale digital sky surveys have produced an unprecedented volume of uniform data covering both vast proportions of the sky and a wide range of wavelength, from the ultraviolet to the near-infrared. The challenge facing astronomers today is how to use this multitude of information to extract trends, outliers and and rare objects. For example, a large sample of single white dwarf stars has the potential to probe the Galaxy through the luminosity function. The aim of this work was to study stellar and planetary remnants in these surveys. In the last few decades, it has been shown that a handful of white dwarfs have remnants of planetary systems around them, in the form of a dusty disc. These are currently providing the best constraints on the composition of extra-solar planetary systems. Finding significant numbers of dusty discs is only possible in large scale digital sky surveys. I ultilised the SDSS DR7 and colour-colour diagrams to and DA white dwarfs from optical photometry. This nearly doubled the number of spectroscopically confirmed DA white dwarfs in the SDSS compared with DR4 [Eisenstein et al., 2006], and introduced nearly 10; 000 photometric-only DA white dwarf candidates. I further cross-matched our white dwarf catalogue with UKIDSS LAS DR8 to carry out the currently largest and deepest untargeted search for low-mass companions to, and dust discs around, DA white dwarfs. Simultaneously, I analyzed Spitzer observations of 15 white dwarfs with metal-polluted atmospheres, all but one having helium-dominated atmospheres. Three of these stars were found to have an infrared excess consistent with a dusty disc. I used the total sample to estimate a typical disc lifetime of log[tdisc(yr)] = 5:6+1:1, which is compatible with the relatively large range estimated from different theoretical models. Subdwarf population synthesis models predicted a vast population of subdwarfs with F to K-type companions, produced in the effcient RLOF formation channel. I used a cross-match of ultraviolet, optical and infrared surveys to search for this unseen population. I select a complementary sample to those found from radial velocity surveys, offering direct tests of binary evolution pathways. Finally, I present a method to use common proper motion white dwarf pairs to constrain the initial-final mass relation, which is extremely uncertain at low masses. In the example I show, one of the stars is a magnetic white dwarf with B ' 6 MG, making this a rare and intriguing system from a magnetic white dwarf formation point of view.

"Air Toxics under the Big Sky": Examining the Effectiveness of Authentic Scientific Research on High School Students' Science Skills and Interest

ERIC Educational Resources Information Center

Ward, Tony J.; Delaloye, Naomi; Adams, Earle Raymond; Ware, Desirae; Vanek, Diana; Knuth, Randy; Hester, Carolyn Laurie; Marra, Nancy Noel; Holian, Andrij

2016-01-01

"Air Toxics Under the Big Sky" is an environmental science outreach/education program that incorporates the Next Generation Science Standards (NGSS) 8 Practices with the goal of promoting knowledge and understanding of authentic scientific research in high school classrooms through air quality research. This research explored: (1)…

No sign (yet) of intergalactic globular clusters in the Local Group

NASA Astrophysics Data System (ADS)

Mackey, A. D.; Beasley, M. A.; Leaman, R.

2016-07-01

We present Gemini Multi-Object Spectrograph (GMOS) imaging of 12 candidate intergalactic globular clusters (IGCs) in the Local Group, identified in a recent survey of the Sloan Digital Sky Survey (SDSS) footprint by di Tullio Zinn & Zinn. Our image quality is sufficiently high, at ˜0.4-0.7 arcsec, that we are able to unambiguously classify all 12 targets as distant galaxies. To reinforce this conclusion we use GMOS images of globular clusters in the M31 halo, taken under very similar conditions, to show that any genuine clusters in the putative IGC sample would be straightforward to distinguish. Based on the stated sensitivity of the di Tullio Zinn & Zinn search algorithm, we conclude that there cannot be a significant number of IGCs with MV ≤ -6 lying unseen in the SDSS area if their properties mirror those of globular clusters in the outskirts of M31 - even a population of 4 would have only a ≈1 per cent chance of non-detection.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tweed, Dylan; Yang, Xiaohu; Li, Shijie

The ELUCID project aims to build a series of realistic cosmological simulations that reproduce the spatial and mass distributions of the galaxies as observed in the Sloan Digital Sky Survey. This requires powerful reconstruction techniques to create constrained initial conditions (ICs). We test the reconstruction method by applying it to several N -body simulations. We use two medium-resolution simulations, which each produced three additional constrained N -body simulations. We compare the resulting friend-of-friend catalogs by using the particle indexes as tracers, and quantify the quality of the reconstruction by varying the main smoothing parameter. The cross-identification method we use provesmore » to be efficient, and the results suggest that the most massive reconstructed halos are effectively traced from the same Lagrangian regions in the ICs. A preliminary time-dependence analysis indicates that high-mass-end halos converge only at a redshift close to the reconstruction redshift. This suggests that, for earlier snapshots, only collections of progenitors may be effectively cross-identified.« less

A satellite AOT derived from the ground sky transmittance measurements

NASA Astrophysics Data System (ADS)

Lim, H. S.; MatJafri, M. Z.; Abdullah, K.; Tan, K. C.; Wong, C. J.; Saleh, N. Mohd.

2008-10-01

The optical properties of aerosols such as smoke from burning vary due to aging processes and these particles reach larger sizes at high concentrations. The objectives of this study are to develop and evaluate an algorithm for estimating atmospheric optical thickness from Landsat TM image. This study measured the sky transmittance at the ground using a handheld spectroradiometer in a wide wavelength spectrum to retrieve atmospheric optical thickness. The in situ measurement of atmospheric transmittance data were collected simultaneously with the acquisition of remotely sensed satellite data. The digital numbers for the three visible bands corresponding to the in situ locations were extracted and then converted into reflectance values. The reflectance measured from the satellite was subtracted by the amount given by the surface reflectance to obtain the atmospheric reflectance. These atmospheric reflectance values were used for calibration of the AOT algorithm. This study developed an empirical method to estimate the AOT values from the sky transmittance values. Finally, a AOT map was generated using the proposed algorithm and colour-coded for visual interpretation.

Physical association and periodicity in quasar families with SDSS and 2MRS

NASA Astrophysics Data System (ADS)

Fulton, C. C.; Arp, H. C.; Hartnett, J. G.

2018-07-01

We have used the Sloan Digital Sky Survey (SDSS) data release 7 (DR7) and the 2MASS (Two Micron All Sky Survey) Redshift Survey (2MRS) Ks ≤11.75 mag data release to test for physical association of candidate companion quasars with putative parent galaxies by virtue of Karlsson periodicity in quasar redshifts. We conducted this analysis using the quasar family detection algorithm described in Fulton and Arp (Astrophys. J. 754:134, 2012) and used therein to analyze the 2dF Galaxy Redshift Survey (2dFGRS) and the 2dF Quasar Redshift Survey (2QZ). The SDSS and 2MRS data sets confirm the 2dF results and allow us to examine additional object behaviors also at high significance.

Radiometry simulation within the end-to-end simulation tool SENSOR

NASA Astrophysics Data System (ADS)

Wiest, Lorenz; Boerner, Anko

2001-02-01

12 An end-to-end simulation is a valuable tool for sensor system design, development, optimization, testing, and calibration. This contribution describes the radiometry module of the end-to-end simulation tool SENSOR. It features MODTRAN 4.0-based look up tables in conjunction with a cache-based multilinear interpolation algorithm to speed up radiometry calculations. It employs a linear reflectance parameterization to reduce look up table size, considers effects due to the topology of a digital elevation model (surface slope, sky view factor) and uses a reflectance class feature map to assign Lambertian and BRDF reflectance properties to the digital elevation model. The overall consistency of the radiometry part is demonstrated by good agreement between ATCOR 4-retrieved reflectance spectra of a simulated digital image cube and the original reflectance spectra used to simulate this image data cube.

Astronomy Podcasting: A Low-Cost Tool for Affecting Attitudes in Diverse Audiences

ERIC Educational Resources Information Center

Gay, Pamela L.; Price, Aaron; Searle, Travis

2007-01-01

Communications and mainstream media are entering a new age of on-demand content. As digital video recorders, like TiVo, change how we watch television, podcasts are taking the spoken word in its own on-demand direction. Astronomy podcasts allow listeners to get up-to-date content on a variety of topics ranging from what's in the sky to what's in…

The Second Data Release of the Sloan Digital Sky Survey

DTIC Science & Technology

2004-07-01

Bernardi,11 Michael R. Blanton,10 John J. Bochanski, Jr.,3 William N. Boroski,2 John W. Briggs ,8 J. Brinkmann,5 Robert J. Brunner,12 Tamás Budavári,7...Walter A. Siegmund,49 Nicole M. Silvestri,3 J. Allyn Smith,29, 50 Vernesa Smolčić,48 Stephanie A. Snedden,5 Albert Stebbins,2 Chris Stoughton,2

Measuring the Apparent Size of the Moon with a Digital Camera

ERIC Educational Resources Information Center

Ellery, Adam; Hughes, Stephen

2012-01-01

The Moon appears to be much larger closer to the horizon than when higher in the sky. This is called the "Moon illusion" since the observed size of the Moon is not actually larger when the Moon is just above the horizon. This paper describes a technique for verifying that the observed size of the Moon is not larger on the horizon. The technique…

Preliminary Parallaxes of 40 L and T Dwarfs from the US Naval Observatory Infrared Astronometry Program

NASA Technical Reports Server (NTRS)

Vrba, F. J.; Henden, A. A.; Liginbuhl, C. B.; Guetter, H. H.; Munn, J. A.

2004-01-01

We present preliminary trigonometric parallaxes and proper motions for 22 L dwarfs and 18 T dwarfs measured using the ASTROCAM infrared imager on the US naval Observatory (USNO) 1.55 m Strand Astrometric Reflector. The results presented here are based on observations obtained between 2000 September and 2002 November; about half of the objects have an observational time baseline of t 1:3 yr and half t 2:0 yr. Despite these short time baselines, the astrometric quality is sufficient to produce significant new results, especially for the nearer T dwarfs. Seven objects are in common with the USNO optical CCD parallax program for quality control and seven in common with the European Southern Observatory 3.5 m New Technology Telescope parallax program. We compare astrometric quality with both of these programs. Relative to absolute parallax corrections are made by employing Two Micron All Sky Survey and/or Sloan Digital Sky Survey photometry for reference-frame stars. We combine USNO infrared and optical parallaxes with the best available California Institute of Technology (CIT) system photometry to determine MJ , MH, and MK values for 37 L dwarfs between spectral types L0 and L8 and 19 T dwarfs between spectral types T0.5 and T8 and present selected absolute magnitude versus spectral type and color diagrams, based on these results. Luminosities and temperatures are estimated for these objects. Of special interest are the distances of several objects that are at or near the L-T dwarf boundary so that this important transition can be better understood. The previously reported early to mid T dwarf luminosity excess is clearly confirmed and found to be present at J, H, and K. The large number of objects that populate this luminosity-excess region indicate that it cannot be due entirely to selection effects. The T dwarf sequence is extended to MJ 16:9 by 2MASS J041519 0935, which, at d 5:74 pc, is found to be the lluminous LOG (L=L )pa

Light pollution: measuring and modelling skyglow. An application in two Portuguese reserves

NASA Astrophysics Data System (ADS)

Lima, Raul Cerveira Pinto Sousa

Outdoors human-made lighting at night causes sky glow, one of the effects of light pollution. Sky glow is rising with the growth of world population. Urban inhabitants are increasingly deprived from a starry sky. However, since light propagates to regions far from where it is produced, light pollution spreads to places where few or none artificial light at night existed, disturbing the quality of the night sky. In this work we assess for the first time the sky brightness of two regions in Portugal, the Peneda-Geres National Park, and the recently created Starlight Reserve Dark Sky® Alqueva. We used a portable unit, a Unihedron Sky Quality Meter-L (SQM-L), to measure the luminance of the night sky. We also tested the SQM-L in a laboratory to a more thorough analysis of the device, and to check the effect of polarization on the unit, suggested by our observations and other users. Our results suggest that the SQM-L is not affected by any measurable effect of polarization, but some guidelines to use the SQM-L in the field are provided based on our work. The data from the field measurement was used to compare to one light pollution propagation model (Kocifaj, 2007), using VIIRS DNB satellite upwards radiance as input to the model. The results obtained from the model are favourably compared to the field measurements. We proceeded to a set of tests with the model to find the best fit. Our best results were achieved by analysing the data by night rather than the global set of data. Our first results were used to apply to the classification of the region of Alqueva to a Starlight Tourism Destination. That classification was attained during the course of this work (December 2011). A guideline on the Peneda-Geres National Park was also implemented after our first results were provided. We believe we have achieved a set of results in a set of parallel issues all related to light pollution that we hope may contribute to the current knowledge on this area of research.

A Full Year's Chandra Exposure on Sloan Digital Sky Survey Quasars from the Chandra Multiwavelength Project

NASA Astrophysics Data System (ADS)

Green, Paul J.; Aldcroft, T. L.; Richards, G. T.; Barkhouse, W. A.; Constantin, A.; Haggard, D.; Karovska, M.; Kim, D.-W.; Kim, M.; Vikhlinin, A.; Anderson, S. F.; Mossman, A.; Kashyap, V.; Myers, A. D.; Silverman, J. D.; Wilkes, B. J.; Tananbaum, H.

2009-01-01

We study the spectral energy distributions and evolution of a large sample of optically selected quasars from the Sloan Digital Sky Survey that were observed in 323 Chandra images analyzed by the Chandra Multiwavelength Project. Our highest-confidence matched sample includes 1135 X-ray detected quasars in the redshift range 0.2 < z < 5.4, representing some 36 Msec of effective exposure. We provide catalogs of QSO properties, and describe our novel method of calculating X-ray flux upper limits and effective sky coverage. Spectroscopic redshifts are available for about 1/3 of the detected sample; elsewhere, redshifts are estimated photometrically. We detect 56 QSOs with redshift z > 3, substantially expanding the known sample. We find no evidence for evolution out to z ~ 5 for either the X-ray photon index Γ or for the ratio of optical/UV to X-ray flux αox. About 10% of detected QSOs show best-fit intrinsic absorbing columns greater than 1022 cm-2, but the fraction might reach ~1/3 if most nondetections are absorbed. We confirm a significant correlation between αox and optical luminosity, but it flattens or disappears for fainter (MB gsim -23) active galactic nucleus (AGN) alone. We report significant hardening of Γ both toward higher X-ray luminosity, and for relatively X-ray loud quasars. These trends may represent a relative increase in nonthermal X-ray emission, and our findings thereby strengthen analogies between Galactic black hole binaries and AGN. For uniformly selected subsamples of narrow-line Seyfert 1s and narrow absorption line QSOs, we find no evidence for unusual distributions of either αox or Γ.

CosmoQuest: Virtual Star Parties as a Conduit to Citizen Science Research

NASA Astrophysics Data System (ADS)

Lewis, Scott; Gugliucci, N. E.; Gay, P. L.; Amateur Astronomer Team; Commentator Team

2013-01-01

CosmoQuest has created an environment that actively engages the public through online star parties while building a growing virtual research center that allows individuals anywhere in the world to participate in and contribute to scientific research. Utilizing the infrastructure of Google+ and YouTube, CosmoQuest has brought optical observational astronomy into homes across the world. Every week astronomers - amateur and professional - meet to share live sky images and to discuss the science behind their beauty during Virtual Star parties. A wide array of optics and digital detectors from varied locations collaborate in a fashion not possible in the standard public star party. Every viewer is able to virtually look through the imaging telescope simultaneously while the equipment owner doesn’t need to worry about accidental mishandling by the public. Digital cameras and CCDs also allow longer exposures of deep-sky objects, something not typical in a standard star party event. Our diversity of equipment - ranging from hand-guided Dobsonian telescopes to 16” Schmidt-Cassegrain telescopes on Paramounts - give viewers the opportunity to experience the sky through different systems. Additional Star Parties focus on special astronomical events, such as eclipses and transits. The annular eclipse of 20 May, 2012 brought together astronomers, space enthusiasts and a curious public into a Google+ Hangout On Air to celebrate the event while advocating safe observing methods and explaining the science behind the phenomenon. Public photos of the eclipse were shared live in the broadcast while video of the event was streamed for thousands of viewers to enjoy. Other special event star parties have focused on the Super Moon, Eros Opposition, and the Venus Transit. In this poster we review the technology behind star parties and the reach of these events.

Two-dimensional Topology of the Sloan Digital Sky Survey

NASA Astrophysics Data System (ADS)

Hoyle, Fiona; Vogeley, Michael S.; Gott, J. Richard, III; Blanton, Michael; Tegmark, Max; Weinberg, David H.; Bahcall, N.; Brinkmann, J.; York, D.

2002-12-01

We present the topology of a volume-limited sample of 11,884 galaxies, selected from an apparent magnitude limited sample of over 100,000 galaxies observed as part of the Sloan Digital Sky Survey (SDSS). The data currently cover three main regions on the sky: one in the Galactic north and one in the south, both at zero degrees declination, and one area in the north at higher declination. Each of these areas covers a wide range of survey longitude but a narrow range of survey latitude, allowing the two-dimensional genus to be measured. The genus curves of the SDSS subsamples are similar, after appropriately normalizing these measurements for the different areas. We sum the genus curves from the three areas to obtain the total genus curve of the SDSS. The total curve has a shape similar to the genus curve derived from mock catalogs drawn from the Hubble volume ΛCDM simulation and is similar to that of a Gaussian random field. Likewise, comparison with the genus of the Two-Degree Field Galaxy Redshift Survey, after normalization for the difference in area, reveals remarkable similarity in the topology of these samples. We test for the effects of galaxy-type segregation by splitting the SDSS data into thirds, based on the u*-r* colors of the galaxies, and measure the genus of the reddest and bluest subsamples. This red/blue split in u*-r* is essentially a split by morphology, as explained by Strateva and coworkers. We find that the genus curve for the reddest galaxies exhibits a ``meatball'' shift of the topology-reflecting the concentration of red galaxies in high-density regions-compared to the bluest galaxies and the full sample, in agreement with predictions from simulations.

DA white dwarfs in Sloan Digital Sky Survey Data Release 7 and a search for infrared excess emission

NASA Astrophysics Data System (ADS)

Girven, J.; Gänsicke, B. T.; Steeghs, D.; Koester, D.

2011-10-01

We present a method which uses colour-colour cuts on the Sloan Digital Sky Survey (SDSS) photometry to select white dwarfs with hydrogen-rich (DA) atmospheres without the recourse to spectroscopy. This method results in a sample of DA white dwarfs that is 95 per cent complete at an efficiency of returning a true DA white dwarf of 62 per cent. The approach was applied to SDSS Data Release 7 for objects with and without SDSS spectroscopy. This led to 4636 spectroscopicially confirmed DA white dwarfs with g≤ 19; a ˜70 per cent increase compared to Eisenstein et al.'s 2006 sample. Including the photometric-only objects, we estimate a factor of 3 increase in DA white dwarfs. We find that the SDSS spectroscopic follow-up is 44 per cent complete for DA white dwarfs with Teff≳ 8000 K. We further cross-correlated the SDSS sample with Data Release 8 of the UKIRT (United Kingdom Infrared Telescope) Infrared Deep Sky Survey (UKIDSS) Large Area Survey. The spectral energy distributions (SED) of both subsets, with and without SDSS spectroscopy, were fitted with white dwarf models to determine the fraction of DA white dwarfs with low-mass stellar companions or dusty debris discs via the detection of excess near-infrared emission. From the spectroscopic sample we find that 2.0 per cent of white dwarfs have an excess consistent with a brown dwarf type companion, with a firm lower limit of 0.8 per cent. From the white dwarfs with photometry only, we find that 1.8 per cent are candidates for having brown dwarf companions. Similarly, both samples show that ˜1 per cent of white dwarfs are candidates for having a dusty debris disc.

THE MULTI-OBJECT, FIBER-FED SPECTROGRAPHS FOR THE SLOAN DIGITAL SKY SURVEY AND THE BARYON OSCILLATION SPECTROSCOPIC SURVEY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smee, Stephen A.; Gunn, James E.; Uomoto, Alan

2013-07-12

We present the design and performance of the multi-object fiber spectrographs for the Sloan Digital Sky Survey (SDSS) and their upgrade for the Baryon Oscillation Spectroscopic Survey (BOSS). Originally commissioned in Fall 1999 on the 2.5-m aperture Sloan Telescope at Apache Point Observatory, the spectrographs produced more than 1.5 million spectra for the SDSS and SDSS-II surveys, enabling a wide variety of Galactic and extra-galactic science including the first observation of baryon acoustic oscillations in 2005. The spectrographs were upgraded in 2009 and are currently in use for BOSS, the flagship survey of the third-generation SDSS-III project. BOSS will measuremore » redshifts of 1.35 million massive galaxies to redshift 0.7 and Lyman-alpha absorption of 160,000 high redshift quasars over 10,000 square degrees of sky, making percent level measurements of the absolute cosmic distance scale of the Universe and placing tight constraints on the equation of state of dark energy. The twin multi-object fiber spectrographs utilize a simple optical layout with reflective collimators, gratings, all-refractive cameras, and state-of-the-art CCD detectors to produce hundreds of spectra simultaneously in two channels over a bandpass covering the near ultraviolet to the near infrared, with a resolving power R = \\lambda/FWHM ~ 2000. Building on proven heritage, the spectrographs were upgraded for BOSS with volume-phase holographic gratings and modern CCD detectors, improving the peak throughput by nearly a factor of two, extending the bandpass to cover 360 < \\lambda < 1000 nm, and increasing the number of fibers from 640 to 1000 per exposure. In this paper we describe the original SDSS spectrograph design and the upgrades implemented for BOSS, and document the predicted and measured performances.« less

The Eleventh and Twelfth Data Releases of the Sloan Digital Sky Survey: Final Data from SDSS-III

NASA Astrophysics Data System (ADS)

Alam, Shadab; Albareti, Franco D.; Allende Prieto, Carlos; Anders, F.; Anderson, Scott F.; Anderton, Timothy; Andrews, Brett H.; Armengaud, Eric; Aubourg, Éric; Bailey, Stephen; Basu, Sarbani; Bautista, Julian E.; Beaton, Rachael L.; Beers, Timothy C.; Bender, Chad F.; Berlind, Andreas A.; Beutler, Florian; Bhardwaj, Vaishali; Bird, Jonathan C.; Bizyaev, Dmitry; Blake, Cullen H.; Blanton, Michael R.; Blomqvist, Michael; Bochanski, John J.; Bolton, Adam S.; Bovy, Jo; Shelden Bradley, A.; Brandt, W. N.; Brauer, D. E.; Brinkmann, J.; Brown, Peter J.; Brownstein, Joel R.; Burden, Angela; Burtin, Etienne; Busca, Nicolás G.; Cai, Zheng; Capozzi, Diego; Carnero Rosell, Aurelio; Carr, Michael A.; Carrera, Ricardo; Chambers, K. C.; Chaplin, William James; Chen, Yen-Chi; Chiappini, Cristina; Chojnowski, S. Drew; Chuang, Chia-Hsun; Clerc, Nicolas; Comparat, Johan; Covey, Kevin; Croft, Rupert A. C.; Cuesta, Antonio J.; Cunha, Katia; da Costa, Luiz N.; Da Rio, Nicola; Davenport, James R. A.; Dawson, Kyle S.; De Lee, Nathan; Delubac, Timothée; Deshpande, Rohit; Dhital, Saurav; Dutra-Ferreira, Letícia; Dwelly, Tom; Ealet, Anne; Ebelke, Garrett L.; Edmondson, Edward M.; Eisenstein, Daniel J.; Ellsworth, Tristan; Elsworth, Yvonne; Epstein, Courtney R.; Eracleous, Michael; Escoffier, Stephanie; Esposito, Massimiliano; Evans, Michael L.; Fan, Xiaohui; Fernández-Alvar, Emma; Feuillet, Diane; Filiz Ak, Nurten; Finley, Hayley; Finoguenov, Alexis; Flaherty, Kevin; Fleming, Scott W.; Font-Ribera, Andreu; Foster, Jonathan; Frinchaboy, Peter M.; Galbraith-Frew, J. G.; García, Rafael A.; García-Hernández, D. A.; García Pérez, Ana E.; Gaulme, Patrick; Ge, Jian; Génova-Santos, R.; Georgakakis, A.; Ghezzi, Luan; Gillespie, Bruce A.; Girardi, Léo; Goddard, Daniel; Gontcho, Satya Gontcho A.; González Hernández, Jonay I.; Grebel, Eva K.; Green, Paul J.; Grieb, Jan Niklas; Grieves, Nolan; Gunn, James E.; Guo, Hong; Harding, Paul; Hasselquist, Sten; Hawley, Suzanne L.; Hayden, Michael; Hearty, Fred R.; Hekker, Saskia; Ho, Shirley; Hogg, David W.; Holley-Bockelmann, Kelly; Holtzman, Jon A.; Honscheid, Klaus; Huber, Daniel; Huehnerhoff, Joseph; Ivans, Inese I.; Jiang, Linhua; Johnson, Jennifer A.; Kinemuchi, Karen; Kirkby, David; Kitaura, Francisco; Klaene, Mark A.; Knapp, Gillian R.; Kneib, Jean-Paul; Koenig, Xavier P.; Lam, Charles R.; Lan, Ting-Wen; Lang, Dustin; Laurent, Pierre; Le Goff, Jean-Marc; Leauthaud, Alexie; Lee, Khee-Gan; Lee, Young Sun; Licquia, Timothy C.; Liu, Jian; Long, Daniel C.; López-Corredoira, Martín; Lorenzo-Oliveira, Diego; Lucatello, Sara; Lundgren, Britt; Lupton, Robert H.; Mack, Claude E., III; Mahadevan, Suvrath; Maia, Marcio A. G.; Majewski, Steven R.; Malanushenko, Elena; Malanushenko, Viktor; Manchado, A.; Manera, Marc; Mao, Qingqing; Maraston, Claudia; Marchwinski, Robert C.; Margala, Daniel; Martell, Sarah L.; Martig, Marie; Masters, Karen L.; Mathur, Savita; McBride, Cameron K.; McGehee, Peregrine M.; McGreer, Ian D.; McMahon, Richard G.; Ménard, Brice; Menzel, Marie-Luise; Merloni, Andrea; Mészáros, Szabolcs; Miller, Adam A.; Miralda-Escudé, Jordi; Miyatake, Hironao; Montero-Dorta, Antonio D.; More, Surhud; Morganson, Eric; Morice-Atkinson, Xan; Morrison, Heather L.; Mosser, Benôit; Muna, Demitri; Myers, Adam D.; Nandra, Kirpal; Newman, Jeffrey A.; Neyrinck, Mark; Nguyen, Duy Cuong; Nichol, Robert C.; Nidever, David L.; Noterdaeme, Pasquier; Nuza, Sebastián E.; O'Connell, Julia E.; O'Connell, Robert W.; O'Connell, Ross; Ogando, Ricardo L. C.; Olmstead, Matthew D.; Oravetz, Audrey E.; Oravetz, Daniel J.; Osumi, Keisuke; Owen, Russell; Padgett, Deborah L.; Padmanabhan, Nikhil; Paegert, Martin; Palanque-Delabrouille, Nathalie; Pan, Kaike; Parejko, John K.; Pâris, Isabelle; Park, Changbom; Pattarakijwanich, Petchara; Pellejero-Ibanez, M.; Pepper, Joshua; Percival, Will J.; Pérez-Fournon, Ismael; P´rez-Ra`fols, Ignasi; Petitjean, Patrick; Pieri, Matthew M.; Pinsonneault, Marc H.; Porto de Mello, Gustavo F.; Prada, Francisco; Prakash, Abhishek; Price-Whelan, Adrian M.; Protopapas, Pavlos; Raddick, M. Jordan; Rahman, Mubdi; Reid, Beth A.; Rich, James; Rix, Hans-Walter; Robin, Annie C.; Rockosi, Constance M.; Rodrigues, Thaíse S.; Rodríguez-Torres, Sergio; Roe, Natalie A.; Ross, Ashley J.; Ross, Nicholas P.; Rossi, Graziano; Ruan, John J.; Rubiño-Martín, J. A.; Rykoff, Eli S.; Salazar-Albornoz, Salvador; Salvato, Mara; Samushia, Lado; Sánchez, Ariel G.; Santiago, Basílio; Sayres, Conor; Schiavon, Ricardo P.; Schlegel, David J.; Schmidt, Sarah J.; Schneider, Donald P.; Schultheis, Mathias; Schwope, Axel D.; Scóccola, C. G.; Scott, Caroline; Sellgren, Kris; Seo, Hee-Jong; Serenelli, Aldo; Shane, Neville; Shen, Yue; Shetrone, Matthew; Shu, Yiping; Silva Aguirre, V.; Sivarani, Thirupathi; Skrutskie, M. F.; Slosar, Anže; Smith, Verne V.; Sobreira, Flávia; Souto, Diogo; Stassun, Keivan G.; Steinmetz, Matthias; Stello, Dennis; Strauss, Michael A.; Streblyanska, Alina; Suzuki, Nao; Swanson, Molly E. C.; Tan, Jonathan C.; Tayar, Jamie; Terrien, Ryan C.; Thakar, Aniruddha R.; Thomas, Daniel; Thomas, Neil; Thompson, Benjamin A.; Tinker, Jeremy L.; Tojeiro, Rita; Troup, Nicholas W.; Vargas-Magaña, Mariana; Vazquez, Jose A.; Verde, Licia; Viel, Matteo; Vogt, Nicole P.; Wake, David A.; Wang, Ji; Weaver, Benjamin A.; Weinberg, David H.; Weiner, Benjamin J.; White, Martin; Wilson, John C.; Wisniewski, John P.; Wood-Vasey, W. M.; Ye`che, Christophe; York, Donald G.; Zakamska, Nadia L.; Zamora, O.; Zasowski, Gail; Zehavi, Idit; Zhao, Gong-Bo; Zheng, Zheng; Zhou, Xu; Zhou, Zhimin; Zou, Hu; Zhu, Guangtun

2015-07-01

The third generation of the Sloan Digital Sky Survey (SDSS-III) took data from 2008 to 2014 using the original SDSS wide-field imager, the original and an upgraded multi-object fiber-fed optical spectrograph, a new near-infrared high-resolution spectrograph, and a novel optical interferometer. All of the data from SDSS-III are now made public. In particular, this paper describes Data Release 11 (DR11) including all data acquired through 2013 July, and Data Release 12 (DR12) adding data acquired through 2014 July (including all data included in previous data releases), marking the end of SDSS-III observing. Relative to our previous public release (DR10), DR12 adds one million new spectra of galaxies and quasars from the Baryon Oscillation Spectroscopic Survey (BOSS) over an additional 3000 deg2 of sky, more than triples the number of H-band spectra of stars as part of the Apache Point Observatory (APO) Galactic Evolution Experiment (APOGEE), and includes repeated accurate radial velocity measurements of 5500 stars from the Multi-object APO Radial Velocity Exoplanet Large-area Survey (MARVELS). The APOGEE outputs now include the measured abundances of 15 different elements for each star. In total, SDSS-III added 5200 deg2 of ugriz imaging; 155,520 spectra of 138,099 stars as part of the Sloan Exploration of Galactic Understanding and Evolution 2 (SEGUE-2) survey; 2,497,484 BOSS spectra of 1,372,737 galaxies, 294,512 quasars, and 247,216 stars over 9376 deg2; 618,080 APOGEE spectra of 156,593 stars; and 197,040 MARVELS spectra of 5513 stars. Since its first light in 1998, SDSS has imaged over 1/3 of the Celestial sphere in five bands and obtained over five million astronomical spectra.

Non-sky polarization-based dehazing algorithm for non-specular objects using polarization difference and global scene feature.

PubMed

Qu, Yufu; Zou, Zhaofan

2017-10-16

Photographic images taken in foggy or hazy weather (hazy images) exhibit poor visibility and detail because of scattering and attenuation of light caused by suspended particles, and therefore, image dehazing has attracted considerable research attention. The current polarization-based dehazing algorithms strongly rely on the presence of a "sky area", and thus, the selection of model parameters is susceptible to external interference of high-brightness objects and strong light sources. In addition, the noise of the restored image is large. In order to solve these problems, we propose a polarization-based dehazing algorithm that does not rely on the sky area ("non-sky"). First, a linear polarizer is used to collect three polarized images. The maximum- and minimum-intensity images are then obtained by calculation, assuming the polarization of light emanating from objects is negligible in most scenarios involving non-specular objects. Subsequently, the polarization difference of the two images is used to determine a sky area and calculate the infinite atmospheric light value. Next, using the global features of the image, and based on the assumption that the airlight and object radiance are irrelevant, the degree of polarization of the airlight (DPA) is calculated by solving for the optimal solution of the correlation coefficient equation between airlight and object radiance; the optimal solution is obtained by setting the right-hand side of the equation to zero. Then, the hazy image is subjected to dehazing. Subsequently, a filtering denoising algorithm, which combines the polarization difference information and block-matching and 3D (BM3D) filtering, is designed to filter the image smoothly. Our experimental results show that the proposed polarization-based dehazing algorithm does not depend on whether the image includes a sky area and does not require complex models. Moreover, the dehazing image except specular object scenarios is superior to those obtained by Tarel, Fattal, Ren, and Berman based on the criteria of no-reference quality assessment (NRQA), blind/referenceless image spatial quality evaluator (BRISQUE), blind anistropic quality index (AQI), and e.

Session 21.2 - Measurement of Light at Night

NASA Astrophysics Data System (ADS)

Wainscoat, Richard J.

2016-10-01

The introduction of the mercury vapor lamp for general lighting in the 1930s probably marked the beginning of significant light pollution. Lighting levels have increased slowly, year-to-year, with sky brightness levels increasing only slowly on timescales of a year; no measurement protocols or instruments existed to quantify this increase. However, on timescales of 10-20 years, or on generational timescales, the increases in night sky levels, particularly in urban areas, have been dramatic. Younger people speak with their parents or grandparents who remark how beautiful the sky used to be, and how many stars they could see when they when they were younger. Older people can themselves remember how many stars were visible in the sky when they were younger. Whole generations of children now grow up without ever seeing the Milky Way. Society has not had tools to easily measure sky brightness, and monitoring from space has only recently become available. A subtle increase of 10% sky brightness per year, for example, is not noticeable to the human eye on the time scale of a year, and has been tolerated by society. But such an increase compounds to an increase of a factor 2.6 in 10 years, 6.7 in 20 years, and a factor 45 in 40 years, corresponding to a dramatic increase in sky brightness, an almost complete loss in ability to see faint objects in the night sky, and rendering the sky unusable for most forms of astronomy. The most striking examples are the urban observatories found in many major cities that can no longer be used. Session 2 was primarily focused on measurement of light at night, with an emphasis on measurement of light pollution. It comprised of 6 papers that are summarized below. Over the last decade, our ability to measure light pollution has grown tremendously, and the instrumentation needed to produce reliable quantitative measurements has become much more affordable, and now includes consumer grade digital cameras and even smart phones. During this same time period, light pollution has continued to grow. The widespread changes from mostly high-pressure sodium lighting to LED lighting that are now occurring make continued monitoring and measurement of light pollution particularly important into the future. Complete presentations may be viewed at: http://www.noao.edu/education/IAUGA2015FM21

Cosmological N-body Simulation

NASA Astrophysics Data System (ADS)

Lake, George

1994-05-01

.90ex> }}} The ``N'' in N-body calculations has doubled every year for the last two decades. To continue this trend, the UW N-body group is working on algorithms for the fast evaluation of gravitational forces on parallel computers and establishing rigorous standards for the computations. In these algorithms, the computational cost per time step is ~ 10(3) pairwise forces per particle. A new adaptive time integrator enables us to perform high quality integrations that are fully temporally and spatially adaptive. SPH--smoothed particle hydrodynamics will be added to simulate the effects of dissipating gas and magnetic fields. The importance of these calculations is two-fold. First, they determine the nonlinear consequences of theories for the structure of the Universe. Second, they are essential for the interpretation of observations. Every galaxy has six coordinates of velocity and position. Observations determine two sky coordinates and a line of sight velocity that bundles universal expansion (distance) together with a random velocity created by the mass distribution. Simulations are needed to determine the underlying structure and masses. The importance of simulations has moved from ex post facto explanation to an integral part of planning large observational programs. I will show why high quality simulations with ``large N'' are essential to accomplish our scientific goals. This year, our simulations have N >~ 10(7) . This is sufficient to tackle some niche problems, but well short of our 5 year goal--simulating The Sloan Digital Sky Survey using a few Billion particles (a Teraflop-year simulation). Extrapolating past trends, we would have to ``wait'' 7 years for this hundred-fold improvement. Like past gains, significant changes in the computational methods are required for these advances. I will describe new algorithms, algorithmic hacks and a dedicated computer to perform Billion particle simulations. Finally, I will describe research that can be enabled by Petaflop computers. This research is supported by the NASA HPCC/ESS program.

LAMOST Spectrograph Response Curves: Stability and Application to Flux Calibration

NASA Astrophysics Data System (ADS)

Du, Bing; Luo, A.-Li; Kong, Xiao; Zhang, Jian-Nan; Guo, Yan-Xin; Cook, Neil James; Hou, Wen; Yang, Hai-Feng; Li, Yin-Bi; Song, Yi-Han; Chen, Jian-Jun; Zuo, Fang; Wu, Ke-Fei; Wang, Meng-Xin; Wu, Yue; Wang, You-Fen; Zhao, Yong-Heng

2016-12-01

The task of flux calibration for Large sky Area Multi-Object Spectroscopic Telescope (LAMOST) spectra is difficult due to many factors, such as the lack of standard stars, flat-fielding for large field of view, and variation of reddening between different stars, especially at low Galactic latitudes. Poor selection, bad spectral quality, or extinction uncertainty of standard stars not only might induce errors to the calculated spectral response curve (SRC) but also might lead to failures in producing final 1D spectra. In this paper, we inspected spectra with Galactic latitude | b| ≥slant 60^\\circ and reliable stellar parameters, determined through the LAMOST Stellar Parameter Pipeline (LASP), to study the stability of the spectrograph. To guarantee that the selected stars had been observed by each fiber, we selected 37,931 high-quality exposures of 29,000 stars from LAMOST DR2, and more than seven exposures for each fiber. We calculated the SRCs for each fiber for each exposure and calculated the statistics of SRCs for spectrographs with both the fiber variations and time variations. The result shows that the average response curve of each spectrograph (henceforth ASPSRC) is relatively stable, with statistical errors ≤10%. From the comparison between each ASPSRC and the SRCs for the same spectrograph obtained by the 2D pipeline, we find that the ASPSRCs are good enough to use for the calibration. The ASPSRCs have been applied to spectra that were abandoned by the LAMOST 2D pipeline due to the lack of standard stars, increasing the number of LAMOST spectra by 52,181 in DR2. Comparing those same targets with the Sloan Digital Sky Survey (SDSS), the relative flux differences between SDSS spectra and LAMOST spectra with the ASPSRC method are less than 10%, which underlines that the ASPSRC method is feasible for LAMOST flux calibration.

Quantifying and Reducing Light Pollution

NASA Astrophysics Data System (ADS)

Gokhale, Vayujeet; Caples, David; Goins, Jordan; Herdman, Ashley; Pankey, Steven; Wren, Emily

2018-06-01

We describe the current level of light pollution in and around Kirksville, Missouri and around Anderson Mesa near Flagstaff, Arizona. We quantify the amount of light that is projected up towards the sky, instead of the ground, using Unihedron sky quality meters installed at various locations. We also present results from DSLR photometry of several standard stars, and compare the photometric quality of the data collected at locations with varying levels of light pollution. Presently, light fixture shields and ‘warm-colored’ lights are being installed on Truman State University’s campus in order to reduce light pollution. We discuss the experimental procedure we use to test the effectiveness of the different light fixtures shields in a controlled setting inside the Del and Norma Robison Planetarium.Apart from negatively affecting the quality of the night sky for astronomers, light pollution adversely affects migratory patterns of some animals and sleep-patterns in humans, increases our carbon footprint, and wastes resources and money. This problem threatens to get particularly acute with the increasing use of outdoor LED lamps. We conclude with a call to action to all professional and amateur astronomers to act against the growing nuisance of light pollution.

New low noise CCD cameras for Pi-of-the-Sky project

NASA Astrophysics Data System (ADS)

Kasprowicz, G.; Czyrkowski, H.; Dabrowski, R.; Dominik, W.; Mankiewicz, L.; Pozniak, K.; Romaniuk, R.; Sitek, P.; Sokolowski, M.; Sulej, R.; Uzycki, J.; Wrochna, G.

2006-10-01

Modern research trends require observation of fainter and fainter astronomical objects on large areas of the sky. This implies usage of systems with high temporal and optical resolution with computer based data acquisition and processing. Therefore Charge Coupled Devices (CCD) became so popular. They offer quick picture conversion with much better quality than film based technologies. This work is theoretical and practical study of the CCD based picture acquisition system. The system was optimized for "Pi of The Sky" project. But it can be adapted to another professional astronomical researches. The work includes issue of picture conversion, signal acquisition, data transfer and mechanical construction of the device.

Retrieval of Garstang's emission function from all-sky camera images

NASA Astrophysics Data System (ADS)

Kocifaj, Miroslav; Solano Lamphar, Héctor Antonio; Kundracik, František

2015-10-01

The emission function from ground-based light sources predetermines the skyglow features to a large extent, while most mathematical models that are used to predict the night sky brightness require the information on this function. The radiant intensity distribution on a clear sky is experimentally determined as a function of zenith angle using the theoretical approach published only recently in MNRAS, 439, 3405-3413. We have made the experiments in two localities in Slovakia and Mexico by means of two digital single lens reflex professional cameras operating with different lenses that limit the system's field-of-view to either 180º or 167º. The purpose of using two cameras was to identify variances between two different apertures. Images are taken at different distances from an artificial light source (a city) with intention to determine the ratio of zenith radiance relative to horizontal irradiance. Subsequently, the information on the fraction of the light radiated directly into the upward hemisphere (F) is extracted. The results show that inexpensive devices can properly identify the upward emissions with adequate reliability as long as the clear sky radiance distribution is dominated by a largest ground-based light source. Highly unstable turbidity conditions can also make the parameter F difficult to find or even impossible to retrieve. The measurements at low elevation angles should be avoided due to a potentially parasitic effect of direct light emissions from luminaires surrounding the measuring site.

Lossy compression of weak lensing data

DOE PAGES

Vanderveld, R. Ali; Bernstein, Gary M.; Stoughton, Chris; ...

2011-07-12

Future orbiting observatories will survey large areas of sky in order to constrain the physics of dark matter and dark energy using weak gravitational lensing and other methods. Lossy compression of the resultant data will improve the cost and feasibility of transmitting the images through the space communication network. We evaluate the consequences of the lossy compression algorithm of Bernstein et al. (2010) for the high-precision measurement of weak-lensing galaxy ellipticities. This square-root algorithm compresses each pixel independently, and the information discarded is by construction less than the Poisson error from photon shot noise. For simulated space-based images (without cosmicmore » rays) digitized to the typical 16 bits per pixel, application of the lossy compression followed by image-wise lossless compression yields images with only 2.4 bits per pixel, a factor of 6.7 compression. We demonstrate that this compression introduces no bias in the sky background. The compression introduces a small amount of additional digitization noise to the images, and we demonstrate a corresponding small increase in ellipticity measurement noise. The ellipticity measurement method is biased by the addition of noise, so the additional digitization noise is expected to induce a multiplicative bias on the galaxies measured ellipticities. After correcting for this known noise-induced bias, we find a residual multiplicative ellipticity bias of m {approx} -4 x 10 -4. This bias is small when compared to the many other issues that precision weak lensing surveys must confront, and furthermore we expect it to be reduced further with better calibration of ellipticity measurement methods.« less

Stroop-like effects in a new-code learning task: A cognitive load theory perspective.

PubMed

Hazan-Liran, Batel; Miller, Paul

2017-09-01

To determine whether and how learning is biased by competing task-irrelevant information that creates extraneous cognitive load, we assessed the efficiency of university students with a learning paradigm in two experiments. The paradigm asked participants to learn associations between eight words and eight digits. We manipulated congruity of the digits' ink colour with the words' semantics. In Experiment 1 word stimuli were colour words (e.g., blue, yellow) and in Experiment 2 colour-related word concepts (e.g., sky, banana). Marked benefits and costs on learning due to variation in extraneous cognitive load originating from processing task-irrelevant information were evident. Implications for cognitive load theory and schooling are discussed.

IRAS sky survey atlas: Explanatory supplement

NASA Technical Reports Server (NTRS)

Wheelock, S. L.; Gautier, T. N.; Chillemi, J.; Kester, D.; Mccallon, H.; Oken, C.; White, J.; Gregorich, D.; Boulanger, F.; Good, J.

1994-01-01

This Explanatory Supplement accompanies the IRAS Sky Survey Atlas (ISSA) and the ISSA Reject Set. The first ISSA release in 1991 covers completely the high ecliptic latitude sky, absolute value of beta is greater than 50 deg, with some coverage down to the absolute value of beta approx. equal to 40 deg. The second ISSA release in 1992 covers ecliptic latitudes of 50 deg greater than the absolute value of beta greater than 20 deg, with some coverage down to the absolute value of beta approx. equal to 13 deg. The remaining fields covering latitudes within 20 deg of the ecliptic plane are of reduced quality compared to the rest of the ISSA fields and therefore are released as a separate IPAC product, the ISSA Reject Set. The reduced quality is due to contamination by zodiacal emission residuals. Special care should be taken when using the ISSA Reject images. In addition to information on the ISSA images, some information is provided in this Explanatory Supplement on the IRAS Zodiacal History File (ZOHF), Version 3.0, which was described in the December 1988 release memo. The data described in this Supplement are available at the National Space Science Data Center (NSSDC) at the Goddard Space Flight Center. The interested reader is referred to the NSSDC for access to the IRAS Sky Survey Atlas (ISSA).

The Third Data Release of the Sloan Digital Sky Survey

DTIC Science & Technology

2005-03-01

Astronomy, MSC 4500, New Mexico State University, P.O. Box 30001, Las Cruces, NM 88003. 6 Department of Astrophysical Sciences, Princeton University... Mexico Institute of Technology, 801 Leroy Place, Socorro, NM 87801. 14 Department of Astronomy, University of Illinois, 1002 West Green Street, Urbana...NJ 08544. 49 FNRS Institut d’Astronomie et d’Astrophysique, Université Libre de Bruxelles, CP. 226, Boulevard du Triomphe, B-1050 Bruxelles, Belgium

First Light for BOSS - A New Kind of Search for Dark Energy | Berkeley

Science.gov Websites

in the clumping of invisible dark matter. Comparing these scales at different eras makes it possible Web People Close About the Lab Leadership/Organization Calendar News Center Today At Berkeley Lab News Preuss, (510) 486-6249 On the night of September 14 the largest program in the Sloan Digital Sky Survey

An Alternative to EPA Method 9 -- Field Validation of the Digital Opacity Compliance System (DOCS)

DTIC Science & Technology

2005-03-15

at the completion of the Phase I and Phase II DOCS field demonstration. These included the following 1) anemometer, 2) sling psychrometer , 3) Abney...anemometer (Eastern Technical Associates, Inc.) Sky conditions Visual observation Relative Humidity Sling Psychrometer (Eastern Technical Associates...least have access to a range of climatic monitoring equipment including the following 1) anemometer, 2) sling psychrometer , 3) Abney Level (sun angle

Double Star Measurements at the Internationale Amateur Sternwarte (IAS) in Namibia in 2008 and 2009

NASA Astrophysics Data System (ADS)

Anton, Rainer

2010-04-01

A 40-cm-Cassegrain telescope in Namibia was used for observing double and multiple systems in the southern sky. Digital images were recorded with a CCD camera at high frame rates via a firewire interface directly in a computer. Measurements of 34 double and multiple systems are presented and compared with literature data. Some noteworthy objects are discussed in more detail.

Predicting the Quasar Photometric Reshift with the Sloan Digital Sky Survey Filter System

NASA Astrophysics Data System (ADS)

Laubacher, Emily M.; York, Donald G.

1999-10-01

Photometric data were obtained for a set of known quasars (QSOs) in five bands with the Sloan Digital Sky Survey (SDSS) filter system for the purpose of testing the ability of the SDSS system to accurately predict the photometric redshift of QSOs. The initial plot of the SDSS photometric redshift versus the measured redshift shows a good relationship, but a lot of scatter. A literature search was conducted on a selected sampling of 49 QSOs, 26 with redshift z <= 0.5 and 23 with 0.5 < z < 2.6, to confirm their accurate identifications as QSOs with their advertised redshifts. This search revealed 10 rejected QSOs which were not QSOs but rather Seyfert galaxies or Narrow Line Objects. Additionally, 11 QSOs were either Broad Absorption Line Systems or had spectra that were in some way incomplete, and therefore, their QSO identification could not be confirmed. The revised plot, with the rejected and unconfirmed QSOs removed, gives an excellent straight line with very little scatter. Although these results are preliminary and for only a small sampling of QSOs, they show that further study of the relationship is warranted and that eventually the SDSS method may be used to accurately predict the photometric redshift of QSOs.

A Deep Proper Motion Catalog Within the Sloan Digital Sky Survey Footprint. II. The White Dwarf Luminosity Function

NASA Astrophysics Data System (ADS)

Munn, Jeffrey A.; Harris, Hugh C.; von Hippel, Ted; Kilic, Mukremin; Liebert, James W.; Williams, Kurtis A.; DeGennaro, Steven; Jeffery, Elizabeth; Dame, Kyra; Gianninas, A.; Brown, Warren R.

2017-01-01

A catalog of 8472 white dwarf (WD) candidates is presented, selected using reduced proper motions from the deep proper motion catalog of Munn et al. Candidates are selected in the magnitude range 16< r< 21.5 over 980 square degrees, and 16< r< 21.3 over an additional 1276 square degrees, within the Sloan Digital Sky Survey (SDSS) imaging footprint. Distances, bolometric luminosities, and atmospheric compositions are derived by fitting SDSS ugriz photometry to pure hydrogen and helium model atmospheres (assuming surface gravities {log} {\\text{}}g=8). The disk white dwarf luminosity function (WDLF) is constructed using a sample of 2839 stars with 5.5< {M}{bol}< 17, with statistically significant numbers of stars cooler than the turnover in the luminosity function. The WDLF for the halo is also constructed, using a sample of 135 halo WDs with 5< {M}{bol}< 16. We find space densities of disk and halo WDs in the solar neighborhood of 5.5+/- 0.1× {10}-3 {{pc}}-3 and 3.5+/- 0.7× {10}-5 {{pc}}-3, respectively. We resolve the bump in the disk WDLF due to the onset of fully convective envelopes in WDs, and see indications of it in the halo WDLF as well.

MEASURING REDDENING WITH SLOAN DIGITAL SKY SURVEY STELLAR SPECTRA AND RECALIBRATING SFD

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schlafly, Edward F.; Finkbeiner, Douglas P.

2011-08-20

We present measurements of dust reddening using the colors of stars with spectra in the Sloan Digital Sky Survey. We measure reddening as the difference between the measured and predicted colors of a star, as derived from stellar parameters from the Sloan Extension for Galactic Understanding and Exploration Stellar Parameter Pipeline. We achieve uncertainties of 56, 34, 25, and 29 mmag in the colors u - g, g - r, r - i, and i - z, per star, though the uncertainty varies depending on the stellar type and the magnitude of the star. The spectrum-based reddening measurements confirm ourmore » earlier 'blue tip' reddening measurements, finding reddening coefficients different by -3%, 1%, 1%, and 2% in u - g, g - r, r - i, and i - z from those found by the blue tip method, after removing a 4% normalization difference. These results prefer an R{sub V} = 3.1 Fitzpatrick reddening law to O'Donnell or Cardelli et al. reddening laws. We provide a table of conversion coefficients from the Schlegel et al. (SFD) maps of E(B - V) to extinction in 88 bandpasses for four values of R{sub V} , using this reddening law and the 14% recalibration of SFD first reported by Schlafly et al. and confirmed in this work.« less

Validation of Observations Obtained with a Liquid Mirror Telescope by Comparison with Sloan Digital Sky Survey Observations

NASA Astrophysics Data System (ADS)

Borra, E. F.

2015-06-01

The results of a search for peculiar astronomical objects using very low resolution spectra obtained with the NASA Orbital Debris Observatory (NODO) 3 m diameter liquid mirror telescope (LMT) are compared with results of spectra obtained with the Sloan Digital Sky Survey (SDSS). The main purpose of this comparison is to verify whether observations taken with this novel type of telescope are reliable. This comparison is important because LMTs are an inexpensive novel type of telescope that is very useful for astronomical surveys, particularly surveys in the time domain, and validation of the data taken with an LMT by comparison with data from a classical telescope will validate their reliability. We start from a published data analysis that classified as peculiar only 206 of the 18,000 astronomical objects observed with the NODO LMT. A total of 29 of these 206 objects were found in the SDSS. The reliability of the NODO data can be seen through the results of the detailed analysis that, in practice, incorrectly identified less than 0.3% of the 18,000 spectra as peculiar objects, most likely because they are variable stars. We conclude that the LMT gave reliable observations, comparable to those that would have been obtained with a telescope using a glass mirror.

A Digital Backend for the Low Frequency All Sky Monitor

NASA Astrophysics Data System (ADS)

Dartez, L. P.

2014-04-01

The Low Frequency All Sky Monitor (LoFASM) is a distributed array of dipole antennas that are sensitive to radio frequencies from 10 to 88 MHz. The primary science goals of LoFASM are the detection and study of low-frequency radio transients, a high priority science goal as deemed by the National Research Council's decadal survey. LoFASM consists of antennas and front-end electronics that were originally developed for the Long Wavelength Array (LWA) by the U.S. Naval Research Lab, the University of New Mexico, Virginia Tech, and the Jet Propulsion Laboratory. LoFASM, funded by the U.S. Department of Defense, will initially consist of four stations, each consisting of 12 dual-polarization dipole antennas. In a single station, RF signals from each of the individual LoFASM dipoles are combined in phase in order to synthesize LoFASM's beam. The LoFASM RF signals are phased up so that the resulting beam is sensitive to radio emission that originates from the zenith and RF signals approaching from the horizon are attenuated. Digitally, this is achieved using a full Stokes 100MHz correlating spectrometer constructed using field programmable gate array (FPGA) technology. In this thesis I will describe the design and usage of the LoFASM Correlator.

The Discovery of a High-Redshift Quasar without Emission Lines from Sloan Digital Sky Survey Commissioning Data.

PubMed

Fan; Strauss; Gunn; Lupton; Carilli; Rupen; Schmidt; Moustakas; Davis; Annis; Bahcall; Brinkmann; Brunner; Csabai; Doi; Fukugita; Heckman; Hennessy; Hindsley; Ivezic; Knapp; Lamb; Munn; Pauls; Pier; Rockosi; Schneider; Szalay; Tucker; York

1999-12-01

We report observations of a luminous unresolved object at redshift z=4.62, with a featureless optical spectrum redward of the Lyalpha forest region, discovered from Sloan Digital Sky Survey commissioning data. The redshift is determined by the onset of the Lyalpha forest at lambda approximately 6800 Å and a Lyman limit system at lambda=5120 Å. A strong Lyalpha absorption system with weak metal absorption lines at z=4.58 is also identified in the spectrum. The object has a continuum absolute magnitude of -26.6 at 1450 Å in the rest frame (h0=0.5, q0=0.5) and therefore cannot be an ordinary galaxy. It shows no radio emission (the 3 sigma upper limit of its flux at 6 cm is 60 µJy), indicating a radio-to-optical flux ratio at least as small as that of the radio-weakest BL Lacertae objects known. It is also not linearly polarized to a 3 sigma upper limit of 4% in the observed I band. Therefore, it is either the most distant BL Lac object known to date, with very weak radio emission, or a new type of unbeamed quasar, whose broad emission line region is very weak or absent.

BOOK REVIEW: Treasure-Hunting in Astronomical Plate Archives.

NASA Astrophysics Data System (ADS)

Kroll, Peter; La Dous, Constanze; Brauer, Hans-Juergen; Sterken, C.

This book consists of the proceedings of a conference on the exploration of the invaluable scientific treasure present in astronomical plate archives worldwide. The book incorporates fifty scientific papers covering almost 250 pages. There are several most useful papers, such as, for example, an introduction to the world's large plate archives that serves the purpose of a guide for the beginning user of plate archives. It includes a very useful list of twelve mayor archives with many details on their advantages (completeness, number of plates, classification system and homogeneity of time coverage) and their limitations (plate quality, access, electronic catalogues, photographic services, limiting magnitudes, search software and cost to the user). Other topics cover available contemporary digitization machines, the applications of commercial flatbed scanners, technical aspects of plate consulting, astrophysical applications and astrometric uses, data reduction, data archiving and retrieval, and strategies to find astrophysically useful information on plates. The astrophysical coverage is very broad: from solar-system bodies to variable stars, sky surveys and sky patrols covering the galactic and extragalactic domain and even gravitational lensing. The book concludes by an illuminating paper on ALADIN, the reference tool for identification of astronomical sources. This work can be considered as a kind of field guide, and is recommended reading for anyone who wishes to undertake small- or large-scale consulting of photographic plate material. A shortcoming of the proceedings is the fact that very few papers have abstracts. BOOK REVIEW: Treasure-Hunting in Astronomical Plate Archives. Proceedings of the international workshop held at Sonneberg Observatory, March 4-6, 1999. Peter Kroll, Constanze la Dous and Hans-Juergen Brauer (Eds.)

IAU Working Group on Wide-Field Imaging.

NASA Astrophysics Data System (ADS)

MacGillivray, H. T.

1991-01-01

Contents: 1. Introduction - The IAU Working Group on Wide-Field Imaging (R. M. West). 2. Reports from the Sub-Sections of the Working Group - a. Sky surveys and patrols (R. M. West). b. Photographic techniques (D. F. Malin). c. Digitization techniques (H. T. MacGillivray). d. Archival and retrieval of wide-field data (B. Lasker). 3. Meeting of the Organising Committee (R. M. West). 4. Wide-field plate archives (M. Tsvetkov). 5. Reproduction of the Palomar Observatory Sky Surveys (R. J. Brucato). 6. Status of the St ScI scan-distribution program (B. Lasker). 7. Pixel addition - pushing Schmidt plates to B = 25 (M. R. S. Hawkins). 8. Photometry from Estar film (S. Phillipps, Q. Parker). 9. ASCHOT - Astrophysical Schmidt Orbital Telescope (H. Lorenz). 10. The Hitchhiker parallel CCD camera (J. Davies, M. Disney, S. Driver, I. Morgan, S. Phillipps).

QUEST1 Variability Survey. III. Light Curve Catalog Update

NASA Astrophysics Data System (ADS)

Rengstorf, A. W.; Thompson, D. L.; Mufson, S. L.; Andrews, P.; Honeycutt, R. K.; Vivas, A. K.; Abad, C.; Adams, B.; Bailyn, C.; Baltay, C.; Bongiovanni, A.; Briceño, C.; Bruzual, G.; Coppi, P.; Della Prugna, F.; Emmet, W.; Ferrín, I.; Fuenmayor, F.; Gebhard, M.; Hernández, J.; Magris, G.; Musser, J.; Naranjo, O.; Oemler, A.; Rosenzweig, P.; Sabbey, C. N.; Sánchez, Ge.; Sánchez, Gu.; Schaefer, B.; Schenner, H.; Sinnott, J.; Snyder, J. A.; Sofia, S.; Stock, J.; van Altena, W.

2009-03-01

This paper reports an update to the QUEST1 (QUasar Equatorial Survey Team, Phase 1) Variability Survey (QVS) light curve catalog, which links QVS instrumental magnitude light curves to Sloan Digital Sky Survey (SDSS) objects and photometry. In the time since the original QVS catalog release, the overlap between publicly available SDSS data and QVS data has increased by 8% in sky coverage and 16,728 in number of matched objects. The astrometric matching and the treatment of SDSS masks have been refined for the updated catalog. We report on these improvements and present multiple bandpass light curves, global variability information, and matched SDSS photometry for 214,941 QUEST1 objects. Based on observations obtained at the Llano del Hato National Astronomical Observatory, operated by the Centro de Investigaciones de Astronomía for the Ministerio de Ciencia y Tecnologia of Venezuela.

A search strategy for SETI - The search for extraterrestrial intelligence

NASA Technical Reports Server (NTRS)

Billingham, J.; Wolfe, J.; Edelson, R.; Gulkis, S.; Olsen, E.; Oliver, B.; Tarter, J.; Seeger, C.

1980-01-01

A search strategy is proposed for the detection of signals of extraterrestrial intelligent origin. It constitutes an exploration of a well defined volume of search space in the microwave region of the spectrum and envisages the use of a combination of sky survey and targeted star approaches. It is predicated on the use of existing antennas equipped with sophisticated multichannel spectrum analyzers and signal processing systems operating in the digital mode. The entire sky would be surveyed between 1 and 10 GHz with resolution bin widths down to 32 Hz. More than 700 nearby solar type stars and other selected interesting directions would be searched between 1 GHz and 3 GHz with bin widths down to 1 Hz. Particular emphasis would be placed on those solar type stars that are within 20 light years of earth.

Digital processing of radiographic images from PACS to publishing.

PubMed

Christian, M E; Davidson, H C; Wiggins, R H; Berges, G; Cannon, G; Jackson, G; Chapman, B; Harnsberger, H R

2001-03-01

Several studies have addressed the implications of filmless radiologic imaging on telemedicine, diagnostic ability, and electronic teaching files. However, many publishers still require authors to submit hard-copy images for publication of articles and textbooks. This study compares the quality digital images directly exported from picture archive and communications systems (PACS) to images digitized from radiographic film. The authors evaluated the quality of publication-grade glossy photographs produced from digital radiographic images using 3 different methods: (1) film images digitized using a desktop scanner and then printed, (2) digital images obtained directly from PACS then printed, and (3) digital images obtained from PACS and processed to improve sharpness prior to printing. Twenty images were printed using each of the 3 different methods and rated for quality by 7 radiologists. The results were analyzed for statistically significant differences among the image sets. Subjective evaluations of the filmless images found them to be of equal or better quality than the digitized images. Direct electronic transfer of PACS images reduces the number of steps involved in creating publication-quality images as well as providing the means to produce high-quality radiographic images in a digital environment.

Color correction optimization with hue regularization

NASA Astrophysics Data System (ADS)

Zhang, Heng; Liu, Huaping; Quan, Shuxue

2011-01-01

Previous work has suggested that observers are capable of judging the quality of an image without any knowledge of the original scene. When no reference is available, observers can extract the apparent objects in an image and compare them with the typical colors of similar objects recalled from their memories. Some generally agreed upon research results indicate that although perfect colorimetric rendering is not conspicuous and color errors can be well tolerated, the appropriate rendition of certain memory colors such as skin, grass, and sky is an important factor in the overall perceived image quality. These colors are appreciated in a fairly consistent manner and are memorized with slightly different hues and higher color saturation. The aim of color correction for a digital color pipeline is to transform the image data from a device dependent color space to a target color space, usually through a color correction matrix which in its most basic form is optimized through linear regressions between the two sets of data in two color spaces in the sense of minimized Euclidean color error. Unfortunately, this method could result in objectionable distortions if the color error biased certain colors undesirably. In this paper, we propose a color correction optimization method with preferred color reproduction in mind through hue regularization and present some experimental results.

Measuring the color and brightness of artificial sky glow from cities using an all-sky imaging system calibrated with astronomical methods in the Johnson-Cousins B and V photometric systems

NASA Astrophysics Data System (ADS)

Pipkin, Ashley; Duriscoe, Dan M.; Lughinbuhl, Christian

2017-01-01

Artificial light at night, when observed at some distance from a city, results in a dome of sky glow, brightest at the horizon. The spectral power distribution of electric light utilized will determine its color of the light dome and the amount of light will determine its brightness. Recent outdoor lighting technologies have included blue-rich light emitting diode (LED) sources that may increase the relative amount of blue to green light in sky glow compared to typical high pressure sodium (HPS) sources with warmer spectra. Measuring and monitoring this effect is important to the preservation of night sky visual quality as seen from undeveloped areas outside the city, such as parks or other protected areas, since the dark-adapted human eye is more sensitive to blue and green. We present a method using a wide field CCD camera which images the entire sky in both Johnson V and B photometric bands. Standard stars within the images are used for calibration. The resulting all-sky brightness maps, and a derived B-V color index map, provide a means to assess and track the impact of specific outdoor lighting practices. We also present example data from several cities, including Las Vegas, Nevada, Flagstaff, Arizona, and Cheyenne, Wyoming.

Planck 2015 results. X. Diffuse component separation: Foreground maps

NASA Astrophysics Data System (ADS)

Planck Collaboration; Adam, R.; Ade, P. A. R.; Aghanim, N.; Alves, M. I. R.; Arnaud, M.; Ashdown, M.; Aumont, J.; Baccigalupi, C.; Banday, A. J.; Barreiro, R. B.; Bartlett, J. G.; Bartolo, N.; Battaner, E.; Benabed, K.; Benoît, A.; Benoit-Lévy, A.; Bernard, J.-P.; Bersanelli, M.; Bielewicz, P.; Bock, J. J.; Bonaldi, A.; Bonavera, L.; Bond, J. R.; Borrill, J.; Bouchet, F. R.; Boulanger, F.; Bucher, M.; Burigana, C.; Butler, R. C.; Calabrese, E.; Cardoso, J.-F.; Catalano, A.; Challinor, A.; Chamballu, A.; Chary, R.-R.; Chiang, H. C.; Christensen, P. R.; Clements, D. L.; Colombi, S.; Colombo, L. P. L.; Combet, C.; Couchot, F.; Coulais, A.; Crill, B. P.; Curto, A.; Cuttaia, F.; Danese, L.; Davies, R. D.; Davis, R. J.; de Bernardis, P.; de Rosa, A.; de Zotti, G.; Delabrouille, J.; Désert, F.-X.; Dickinson, C.; Diego, J. M.; Dole, H.; Donzelli, S.; Doré, O.; Douspis, M.; Ducout, A.; Dupac, X.; Efstathiou, G.; Elsner, F.; Enßlin, T. A.; Eriksen, H. K.; Falgarone, E.; Fergusson, J.; Finelli, F.; Forni, O.; Frailis, M.; Fraisse, A. A.; Franceschi, E.; Frejsel, A.; Galeotta, S.; Galli, S.; Ganga, K.; Ghosh, T.; Giard, M.; Giraud-Héraud, Y.; Gjerløw, E.; González-Nuevo, J.; Górski, K. M.; Gratton, S.; Gregorio, A.; Gruppuso, A.; Gudmundsson, J. E.; Hansen, F. K.; Hanson, D.; Harrison, D. L.; Helou, G.; Henrot-Versillé, S.; Hernández-Monteagudo, C.; Herranz, D.; Hildebrandt, S. R.; Hivon, E.; Hobson, M.; Holmes, W. A.; Hornstrup, A.; Hovest, W.; Huffenberger, K. M.; Hurier, G.; Jaffe, A. H.; Jaffe, T. R.; Jones, W. C.; Juvela, M.; Keihänen, E.; Keskitalo, R.; Kisner, T. S.; Kneissl, R.; Knoche, J.; Kunz, M.; Kurki-Suonio, H.; Lagache, G.; Lähteenmäki, A.; Lamarre, J.-M.; Lasenby, A.; Lattanzi, M.; Lawrence, C. R.; Le Jeune, M.; Leahy, J. P.; Leonardi, R.; Lesgourgues, J.; Levrier, F.; Liguori, M.; Lilje, P. B.; Linden-Vørnle, M.; López-Caniego, M.; Lubin, P. M.; Macías-Pérez, J. F.; Maggio, G.; Maino, D.; Mandolesi, N.; Mangilli, A.; Maris, M.; Marshall, D. J.; Martin, P. G.; Martínez-González, E.; Masi, S.; Matarrese, S.; McGehee, P.; Meinhold, P. R.; Melchiorri, A.; Mendes, L.; Mennella, A.; Migliaccio, M.; Mitra, S.; Miville-Deschênes, M.-A.; Moneti, A.; Montier, L.; Morgante, G.; Mortlock, D.; Moss, A.; Munshi, D.; Murphy, J. A.; Naselsky, P.; Nati, F.; Natoli, P.; Netterfield, C. B.; Nørgaard-Nielsen, H. U.; Noviello, F.; Novikov, D.; Novikov, I.; Orlando, E.; Oxborrow, C. A.; Paci, F.; Pagano, L.; Pajot, F.; Paladini, R.; Paoletti, D.; Partridge, B.; Pasian, F.; Patanchon, G.; Pearson, T. J.; Perdereau, O.; Perotto, L.; Perrotta, F.; Pettorino, V.; Piacentini, F.; Piat, M.; Pierpaoli, E.; Pietrobon, D.; Plaszczynski, S.; Pointecouteau, E.; Polenta, G.; Pratt, G. W.; Prézeau, G.; Prunet, S.; Puget, J.-L.; Rachen, J. P.; Reach, W. T.; Rebolo, R.; Reinecke, M.; Remazeilles, M.; Renault, C.; Renzi, A.; Ristorcelli, I.; Rocha, G.; Rosset, C.; Rossetti, M.; Roudier, G.; Rubiño-Martín, J. A.; Rusholme, B.; Sandri, M.; Santos, D.; Savelainen, M.; Savini, G.; Scott, D.; Seiffert, M. D.; Shellard, E. P. S.; Spencer, L. D.; Stolyarov, V.; Stompor, R.; Strong, A. W.; Sudiwala, R.; Sunyaev, R.; Sutton, D.; Suur-Uski, A.-S.; Sygnet, J.-F.; Tauber, J. A.; Terenzi, L.; Toffolatti, L.; Tomasi, M.; Tristram, M.; Tucci, M.; Tuovinen, J.; Umana, G.; Valenziano, L.; Valiviita, J.; Van Tent, F.; Vielva, P.; Villa, F.; Wade, L. A.; Wandelt, B. D.; Wehus, I. K.; Wilkinson, A.; Yvon, D.; Zacchei, A.; Zonca, A.

2016-09-01

Planck has mapped the microwave sky in temperature over nine frequency bands between 30 and 857 GHz and in polarization over seven frequency bands between 30 and 353 GHz in polarization. In this paper we consider the problem of diffuse astrophysical component separation, and process these maps within a Bayesian framework to derive an internally consistent set of full-sky astrophysical component maps. Component separation dedicated to cosmic microwave background (CMB) reconstruction is described in a companion paper. For the temperature analysis, we combine the Planck observations with the 9-yr Wilkinson Microwave Anisotropy Probe (WMAP) sky maps and the Haslam et al. 408 MHz map, to derive a joint model of CMB, synchrotron, free-free, spinning dust, CO, line emission in the 94 and 100 GHz channels, and thermal dust emission. Full-sky maps are provided for each component, with an angular resolution varying between 7.´5 and 1deg. Global parameters (monopoles, dipoles, relative calibration, and bandpass errors) are fitted jointly with the sky model, and best-fit values are tabulated. For polarization, the model includes CMB, synchrotron, and thermal dust emission. These models provide excellent fits to the observed data, with rms temperature residuals smaller than 4μK over 93% of the sky for all Planck frequencies up to 353 GHz, and fractional errors smaller than 1% in the remaining 7% of the sky. The main limitations of the temperature model at the lower frequencies are internal degeneracies among the spinning dust, free-free, and synchrotron components; additional observations from external low-frequency experiments will be essential to break these degeneracies. The main limitations of the temperature model at the higher frequencies are uncertainties in the 545 and 857 GHz calibration and zero-points. For polarization, the main outstanding issues are instrumental systematics in the 100-353 GHz bands on large angular scales in the form of temperature-to-polarization leakage, uncertainties in the analogue-to-digital conversion, and corrections for the very long time constant of the bolometer detectors, all of which are expected to improve in the near future.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Adam, R.; Ade, P. A. R.; Aghanim, N.

We report that Planck has mapped the microwave sky in temperature over nine frequency bands between 30 and 857 GHz and in polarization over seven frequency bands between 30 and 353 GHz in polarization. In this paper we consider the problem of diffuse astrophysical component separation, and process these maps within a Bayesian framework to derive an internally consistent set of full-sky astrophysical component maps. Component separation dedicated to cosmic microwave background (CMB) reconstruction is described in a companion paper. For the temperature analysis, we combine the Planck observations with the 9-yr Wilkinson Microwave Anisotropy Probe (WMAP) sky maps andmore » the Haslam et al. 408 MHz map, to derive a joint model of CMB, synchrotron, free-free, spinning dust, CO, line emission in the 94 and 100 GHz channels, and thermal dust emission. Full-sky maps are provided for each component, with an angular resolution varying between 7.5 and 1deg. Global parameters (monopoles, dipoles, relative calibration, and bandpass errors) are fitted jointly with the sky model, and best-fit values are tabulated. For polarization, the model includes CMB, synchrotron, and thermal dust emission. These models provide excellent fits to the observed data, with rms temperature residuals smaller than 4μK over 93% of the sky for all Planck frequencies up to 353 GHz, and fractional errors smaller than 1% in the remaining 7% of the sky. The main limitations of the temperature model at the lower frequencies are internal degeneracies among the spinning dust, free-free, and synchrotron components; additional observations from external low-frequency experiments will be essential to break these degeneracies. The main limitations of the temperature model at the higher frequencies are uncertainties in the 545 and 857 GHz calibration and zero-points. For polarization, the main outstanding issues are instrumental systematics in the 100–353 GHz bands on large angular scales in the form of temperature-to-polarization leakage, uncertainties in the analogue-to-digital conversion, and corrections for the very long time constant of the bolometer detectors, all of which are expected to improve in the near future.« less

Planck 2015 results: X. Diffuse component separation: Foreground maps

DOE PAGES

Adam, R.; Ade, P. A. R.; Aghanim, N.; ...

2016-09-20

We report that Planck has mapped the microwave sky in temperature over nine frequency bands between 30 and 857 GHz and in polarization over seven frequency bands between 30 and 353 GHz in polarization. In this paper we consider the problem of diffuse astrophysical component separation, and process these maps within a Bayesian framework to derive an internally consistent set of full-sky astrophysical component maps. Component separation dedicated to cosmic microwave background (CMB) reconstruction is described in a companion paper. For the temperature analysis, we combine the Planck observations with the 9-yr Wilkinson Microwave Anisotropy Probe (WMAP) sky maps andmore » the Haslam et al. 408 MHz map, to derive a joint model of CMB, synchrotron, free-free, spinning dust, CO, line emission in the 94 and 100 GHz channels, and thermal dust emission. Full-sky maps are provided for each component, with an angular resolution varying between 7.5 and 1deg. Global parameters (monopoles, dipoles, relative calibration, and bandpass errors) are fitted jointly with the sky model, and best-fit values are tabulated. For polarization, the model includes CMB, synchrotron, and thermal dust emission. These models provide excellent fits to the observed data, with rms temperature residuals smaller than 4μK over 93% of the sky for all Planck frequencies up to 353 GHz, and fractional errors smaller than 1% in the remaining 7% of the sky. The main limitations of the temperature model at the lower frequencies are internal degeneracies among the spinning dust, free-free, and synchrotron components; additional observations from external low-frequency experiments will be essential to break these degeneracies. The main limitations of the temperature model at the higher frequencies are uncertainties in the 545 and 857 GHz calibration and zero-points. For polarization, the main outstanding issues are instrumental systematics in the 100–353 GHz bands on large angular scales in the form of temperature-to-polarization leakage, uncertainties in the analogue-to-digital conversion, and corrections for the very long time constant of the bolometer detectors, all of which are expected to improve in the near future.« less

VizieR Online Data Catalog: HerMES Large Mode Survey catalogue (Asboth+, 2016)

NASA Astrophysics Data System (ADS)

Asboth, V.; Conley, A.; Sayers, J.; Bethermin, M.; Chapman, S. C.; Clements, D. L.; Cooray, A.; Dannerbauer, H.; Farrah, D.; Glenn, J.; Golwala, S. R.; Halpern, M.; Ibar, E.; Ivison, R. J.; Maloney, P. R.; Marques-Chaves, R.; Martinez-Navajas, P. I.; Oliver, S. J.; Perez-Fournon, I.; Riechers, D. A.; Rowan-Robinson, M.; Scott, D.; Siegel, S. R.; Vieira, J. D.; Viero, M.; Wang, L.; Wardlow, J.; Wheeler, J.

2018-01-01

The HerMES Large Mode Survey (HeLMS) consists of a large area shallow observation of an equatorial field at wavelengths of 250, 350 and 500um, obtained using the SPIRE aboard the Herschel Space Observatory. HeLMS is an extension of HerMES (Oliver et al., 2012MNRAS.424.1614O, Cat. VIII/95 and VIII/103), a 'wedding cake' type survey containing small and deep maps and larger shallower observations of different fields. HeLMS covers about 302deg2 of the sky, making it the largest area observed in the HerMES. The HeLMS field spans 23h14m

Generative adversarial networks recover features in astrophysical images of galaxies beyond the deconvolution limit

NASA Astrophysics Data System (ADS)

Schawinski, Kevin; Zhang, Ce; Zhang, Hantian; Fowler, Lucas; Santhanam, Gokula Krishnan

2017-05-01

Observations of astrophysical objects such as galaxies are limited by various sources of random and systematic noise from the sky background, the optical system of the telescope and the detector used to record the data. Conventional deconvolution techniques are limited in their ability to recover features in imaging data by the Shannon-Nyquist sampling theorem. Here, we train a generative adversarial network (GAN) on a sample of 4550 images of nearby galaxies at 0.01 < z < 0.02 from the Sloan Digital Sky Survey and conduct 10× cross-validation to evaluate the results. We present a method using a GAN trained on galaxy images that can recover features from artificially degraded images with worse seeing and higher noise than the original with a performance that far exceeds simple deconvolution. The ability to better recover detailed features such as galaxy morphology from low signal to noise and low angular resolution imaging data significantly increases our ability to study existing data sets of astrophysical objects as well as future observations with observatories such as the Large Synoptic Sky Telescope (LSST) and the Hubble and James Webb space telescopes.

Tracking the dynamics of skyglow with differential photometry using a digital camera with fisheye lens

NASA Astrophysics Data System (ADS)

Jechow, Andreas; Ribas, Salvador J.; Domingo, Ramon Canal; Hölker, Franz; Kolláth, Zoltán; Kyba, Christopher C. M.

2018-04-01

Artificial skyglow is dynamic due to changing atmospheric conditions and the switching on and off of artificial lights throughout the night. Street lights as well as the ornamental illumination of historical sites and buildings are sometimes switched off at a certain time to save energy. Ornamental lights in particular are often directed upwards, and can therefore have a major contribution towards brightening of the night sky. Here we use differential photometry to investigate the change in night sky brightness and illuminance during an automated regular switch-off of ornamental light in the town of Balaguer and an organized switch-off of all public lights in the village of Àger, both near Montsec Astronomical Park in Spain. The sites were observed during two nights with clear and cloudy conditions using a DSLR camera and a fisheye lens. A time series of images makes it possible to track changes in lighting conditions and sky brightness simultaneously. During the clear night, the ornamental lights in Balaguer contribute over 20% of the skyglow at zenith at the observational site. Furthermore, we are able to track very small changes in the ground illuminance on a cloudy night near Àger.

A Neural Network Based Intelligent Predictive Sensor for Cloudiness, Solar Radiation and Air Temperature

PubMed Central

Ferreira, Pedro M.; Gomes, João M.; Martins, Igor A. C.; Ruano, António E.

2012-01-01

Accurate measurements of global solar radiation and atmospheric temperature, as well as the availability of the predictions of their evolution over time, are important for different areas of applications, such as agriculture, renewable energy and energy management, or thermal comfort in buildings. For this reason, an intelligent, light-weight and portable sensor was developed, using artificial neural network models as the time-series predictor mechanisms. These have been identified with the aid of a procedure based on the multi-objective genetic algorithm. As cloudiness is the most significant factor affecting the solar radiation reaching a particular location on the Earth surface, it has great impact on the performance of predictive solar radiation models for that location. This work also represents one step towards the improvement of such models by using ground-to-sky hemispherical colour digital images as a means to estimate cloudiness by the fraction of visible sky corresponding to clouds and to clear sky. The implementation of predictive models in the prototype has been validated and the system is able to function reliably, providing measurements and four-hour forecasts of cloudiness, solar radiation and air temperature. PMID:23202230

The Large Sky Area Multi-Object Fibre Spectroscopic Telescope (LAMOST) Quasar Survey: Quasar Properties from Data Release Two and Three

NASA Astrophysics Data System (ADS)

Dong, X. Y.; Wu, Xue-Bing; Ai, Y. L.; Yang, J. Y.; Yang, Q.; Wang, F.; Zhang, Y. X.; Luo, A. L.; Xu, H.; Yuan, H. L.; Zhang, J. N.; Wang, M. X.; Wang, L. L.; Li, Y. B.; Zuo, F.; Hou, W.; Guo, Y. X.; Kong, X.; Chen, X. Y.; Wu, Y.; Yang, H. F.; Yang, M.

2018-05-01

This is the second installment for the Large Sky Area Multi-Object Fibre Spectroscopic Telescope (LAMOST) Quasar Survey, which includes quasars observed from 2013 September to 2015 June. There are 9024 confirmed quasars in DR2 and 10911 in DR3. After cross-match with the Sloan Digital Sky Survey (SDSS) quasar catalogs and NED, 12126 quasars are discovered independently. Among them, 2225 quasars were released by SDSS DR12 QSO catalog in 2014 after we finalized the survey candidates. 1801 sources were identified by SDSS DR14 as QSOs. The remaining 8100 quasars are considered as newly founded, and among them, 6887 quasars can be given reliable emission line measurements and the estimated black hole masses. Quasars found in LAMOST are mostly located at low-to-moderate redshifts, with a mean value of 1.5. The highest redshift observed in DR2 and DR3 is 5. We applied emission line measurements to Hα, Hβ, Mg II, and C IV. We deduced the monochromatic continuum luminosities using photometry data, and estimated the virial black hole masses for the newly discovered quasars. Results are compiled into a quasar catalog, which will be available online.

Night-sky brightness monitoring in Hong Kong: a city-wide light pollution assessment.

PubMed

Pun, Chun Shing Jason; So, Chu Wing

2012-04-01

Results of the first comprehensive light pollution survey in Hong Kong are presented. The night-sky brightness was measured and monitored around the city using a portable light-sensing device called the Sky Quality Meter over a 15-month period beginning in March 2008. A total of 1,957 data sets were taken at 199 distinct locations, including urban and rural sites covering all 18 Administrative Districts of Hong Kong. The survey shows that the environmental light pollution problem in Hong Kong is severe-the urban night skies (sky brightness at 15.0 mag arcsec(- 2)) are on average ~ 100 times brighter than at the darkest rural sites (20.1 mag arcsec(- 2)), indicating that the high lighting densities in the densely populated residential and commercial areas lead to light pollution. In the worst polluted urban location studied, the night-sky at 13.2 mag arcsec(- 2) can be over 500 times brighter than the darkest sites in Hong Kong. The observed night-sky brightness is found to be affected by human factors such as land utilization and population density of the observation sites, together with meteorological and/or environmental factors. Moreover, earlier night skies (at 9:30 p.m. local time) are generally brighter than later time (at 11:30 p.m.), which can be attributed to some public and commercial lightings being turned off later at night. On the other hand, no concrete relationship between the observed sky brightness and air pollutant concentrations could be established with the limited survey sampling. Results from this survey will serve as an important database for the public to assess whether new rules and regulations are necessary to control the use of outdoor lightings in Hong Kong.

Cosmic Light: Educating the Public about the Dark Side of IYL

NASA Astrophysics Data System (ADS)

Walker, Constance Elaine; Green, Richard F.

2015-08-01

A role of IAU Commission 50 (C50) on Protection of Existing and Potential Observatory Sites is to provide an interface to key international activities with potential impact on sites, as well as outdoor lighting design practices and public perception. The current prominent example is IAU’s interface to the International Year of Light (IYL), for which C50 proposed and initiated an IYL Working Group (WG) called Cosmic Light with strong overlap with its own Steering Committee, which was then formally established as an Executive Committee WG. The WG became the point of contact for the IYL organizers from the physics/photonics community, and solicited and selected proposals for IAU seed money for programs of international scope. The funded proposals were all de facto continuations of efforts initiated for the IYA. They include the Galileoscope; the “Light Beyond the Bulb” exhibit of images built on the heritage of “From the Earth to the Universe” and a group of “Dark Sky Awareness” educational materials, including a sky measuring app for iPhones, newly-designed Quality Lighting Teaching Kits, a powerful set of “DarkSky EDU” materials, and a Globe at Night program tuned to the IYL. A major criterion was sustainability - that the project would continue beyond the IYL itself, and have ongoing impact for astronomy and dark skies education and outreach.The WG also encouraged and endorsed strong national and regional outreach efforts and participated in the planning for the opening ceremonies and highly visible global activities such as Einstein’s birthday celebration (using hashtag #31415), Super Pi Day (14 March), International Night of Sky Glow Observations (14 March & 12 September), Earth Hour (28 March), International Dark-Sky Week (13-18 April), the Earth and Sky Photo Contest (due 22 April), Global Open Lab Days (9-25 May), the Eratosthenes Project 2015 (measurements 21 June & 21 September), 100 Hours of Light (25-28 September), the international Einstein centenary day for General Relativity and gravitation (25 November) and an XPhoton Challenge on quality lighting and dark skies preservation. Updates, future plans and a guide on participation will be given during the presentation. More information is at http://www.iau.org/iyl/.

Multiscale image processing and antiscatter grids in digital radiography.

PubMed

Lo, Winnie Y; Hornof, William J; Zwingenberger, Allison L; Robertson, Ian D

2009-01-01

Scatter radiation is a source of noise and results in decreased signal-to-noise ratio and thus decreased image quality in digital radiography. We determined subjectively whether a digitally processed image made without a grid would be of similar quality to an image made with a grid but without image processing. Additionally the effects of exposure dose and of a using a grid with digital radiography on overall image quality were studied. Thoracic and abdominal radiographs of five dogs of various sizes were made. Four acquisition techniques were included (1) with a grid, standard exposure dose, digital image processing; (2) without a grid, standard exposure dose, digital image processing; (3) without a grid, half the exposure dose, digital image processing; and (4) with a grid, standard exposure dose, no digital image processing (to mimic a film-screen radiograph). Full-size radiographs as well as magnified images of specific anatomic regions were generated. Nine reviewers rated the overall image quality subjectively using a five-point scale. All digitally processed radiographs had higher overall scores than nondigitally processed radiographs regardless of patient size, exposure dose, or use of a grid. The images made at half the exposure dose had a slightly lower quality than those made at full dose, but this was only statistically significant in magnified images. Using a grid with digital image processing led to a slight but statistically significant increase in overall quality when compared with digitally processed images made without a grid but whether this increase in quality is clinically significant is unknown.

MaNGA: Mapping Nearby Galaxies at Apache Point Observatory

NASA Astrophysics Data System (ADS)

Weijmans, A.-M.; MaNGA Team

2016-10-01

MaNGA (Mapping Nearby Galaxies at APO) is a galaxy integral-field spectroscopic survey within the fourth generation Sloan Digital Sky Survey (SDSS-IV). It will be mapping the composition and kinematics of gas and stars in 10,000 nearby galaxies, using 17 differently sized fiber bundles. MaNGA's goal is to provide new insights in galaxy formation and evolution, and to deliver a local benchmark for current and future high-redshift studies.

Galaxy M101

NASA Image and Video Library

2003-07-25

This three-color image of galaxy M101 was taken by NASA's Galaxy Evolution Explorer on June 20, 2003. The far ultraviolet emissions are shown in blue, the near ultraviolet emissions are green, and the red emissions, which were taken from NASA's Digital Sky Survey, represent visible light. This image combines short, medium, and long "exposure" pictures to best display the evolution of star formation in a spiral galaxy. http://photojournal.jpl.nasa.gov/catalog/PIA04630

Supernova SN 2014C Optical and X-Ray

NASA Image and Video Library

2017-01-24

This visible-light image from the Sloan Digital Sky Survey shows spiral galaxy NGC 7331, center, where astronomers observed the unusual supernova SN 2014C . The inset images are from NASA's Chandra X-ray Observatory, showing a small region of the galaxy before the supernova explosion (left) and after it (right). Red, green and blue colors are used for low, medium and high-energy X-rays, respectively. http://photojournal.jpl.nasa.gov/catalog/PIA21088

42 CFR 37.44 - Approval of radiographic facilities that use digital radiography systems.

Code of Federal Regulations, 2013 CFR

2013-10-01

... image acquisition, digitization, processing, compression, transmission, display, archiving, and... quality digital chest radiographs by submitting to NIOSH digital radiographic image files of a test object... digital radiographic image files from six or more sample chest radiographs that are of acceptable quality...

42 CFR 37.44 - Approval of radiographic facilities that use digital radiography systems.

Code of Federal Regulations, 2012 CFR

2012-10-01

... image acquisition, digitization, processing, compression, transmission, display, archiving, and... quality digital chest radiographs by submitting to NIOSH digital radiographic image files of a test object... digital radiographic image files from six or more sample chest radiographs that are of acceptable quality...

Discovery of Four Field Methane (T-Type) Dwarfs with the Two Micron All-Sky Survey

NASA Astrophysics Data System (ADS)

Burgasser, Adam J.; Kirkpatrick, J. Davy; Brown, Michael E.; Reid, I. Neill; Gizis, John E.; Dahn, Conard C.; Monet, David G.; Beichman, Charles A.; Liebert, James; Cutri, Roc M.; Skrutskie, Michael F.

1999-09-01

We report the discovery of four field methane (``T''-type) brown dwarfs using Two Micron All-Sky Survey (2MASS) data. One additional methane dwarf, previously discovered by the Sloan Digital Sky Survey, was also identified. Near-infrared spectra clearly show the 1.6 and 2.2 μm CH4 absorption bands characteristic of objects with Teff<~1300 K as well as broadened H2O bands at 1.4 and 1.9 μm. Comparing the spectra of these objects with that of Gl 229B, we propose that all new 2MASS T dwarfs are warmer than 950 K, in order from warmest to coolest: 2MASS J1217-03, 2MASS J1225-27, 2MASS J1047+21, and 2MASS J1237+65. Based on this preliminary sample, we find a warm T dwarf surface density of 0.0022 T dwarfs deg-2, or ~90 warm T dwarfs over the whole sky detectable to J<16. The resulting space density upper limit, 0.01 T dwarfs pc-3, is comparable to that of the first L dwarf sample from Kirkpatrick et al. Portions of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by generous financial support of the W. M. Keck Foundation.

Hunting the most distant stars in the Milky Way: methods and initial results

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bochanski, John J.; Willman, Beth; West, Andrew A.

2014-04-01

We present a new catalog of 404 M giant candidates found in the UKIRT Infrared Deep Sky Survey (UKIDSS). The 2400 deg{sup 2} available in the UKIDSS Large Area Survey Data Release 8 resolve M giants through a volume four times larger than that of the entire Two Micron All Sky Survey. Combining near-infrared photometry with optical photometry and proper motions from the Sloan Digital Sky Survey yields an M giant candidate catalog with less M dwarf and quasar contamination than previous searches for similarly distant M giants. Extensive follow-up spectroscopy of this sample will yield the first map ofmore » our Galaxy's outermost reaches over a large area of sky. Our initial spectroscopic follow-up of ∼30 bright candidates yielded the positive identification of five M giants at distances ∼20-90 kpc. Each of these confirmed M giants have positions and velocities consistent with the Sagittarius stream. The fainter M giant candidates in our sample have estimated photometric distances ∼200 kpc (assuming [Fe/H] = 0.0), but require further spectroscopic verification. The photometric distance estimates extend beyond the Milky Way's virial radius, and increase by ∼50% for each 0.5 dex decrease in assumed [Fe/H]. Given the number of M giant candidates, initial selection efficiency, and volume surveyed, we loosely estimate that at least one additional Sagittarius-like accretion event could have contributed to the hierarchical build-up of the Milky Way's outer halo.« less

Morphologies and ages of star cluster pairs and multiplets in the Small Magellanic Cloud

NASA Astrophysics Data System (ADS)

de Oliveira, M. R.; Dutra, C. M.; Bica, E.; Dottori, H.

2000-10-01

An isophotal atlas of 75 star cluster pairs and multiplets in the Small Magellanic Cloud is presented, comprising 176 objects. They are concentrated in the SMC main body. The isophotal contours were made from Digitized Sky Survey* images and showed relevant structural features possibly related to interactions in about 25% of the sample. Previous N-body simulations indicate that such shapes could be due to tidal tails, bridges or common envelopes. The diameter ratio between the members of a pair is preferentially in the range 1 - 2, with a peak at 1. The projected separation is in the range ~ 3 - 22 pc with a pronounced peak at ~ 13 pc. For 91 objects it was possible to derive ages from Colour-Magnitude Diagrams using the OGLE-II photometric survey. The cluster multiplets in general occur in OB stellar associations and/or HII region complexes. This indicates a common origin and suggests that multiplets coalesce into pairs or single clusters in a short time scale. Pairs in the SMC appear to be mostly coeval and consequently captures are a rare phenomenon. We find evidence that star cluster pairs and multiplets may have had an important role in the dynamical history of clusters presently seen as large single objects. The images in this study are based on photographic data obtained using the UK Schmidt Telescope, which was operated by the Royal Observatory Edinburgh, with funding from the UK Science and Engineering Research Council, until 1988 June, and thereafter by the Anglo-Australian Observatory. Original plate material is copyright by the Royal Observatory Edinburgh and the Anglo-Australian Observatory. The plates were processed into the present compressed digital form with their permission. The Digitized Sky Survey was produced at the Space Telescope Science Institute under US Government grant NAG W-2166.

Multivariate statistical analysis software technologies for astrophysical research involving large data bases

NASA Technical Reports Server (NTRS)

Djorgovski, S. George

1994-01-01

We developed a package to process and analyze the data from the digital version of the Second Palomar Sky Survey. This system, called SKICAT, incorporates the latest in machine learning and expert systems software technology, in order to classify the detected objects objectively and uniformly, and facilitate handling of the enormous data sets from digital sky surveys and other sources. The system provides a powerful, integrated environment for the manipulation and scientific investigation of catalogs from virtually any source. It serves three principal functions: image catalog construction, catalog management, and catalog analysis. Through use of the GID3* Decision Tree artificial induction software, SKICAT automates the process of classifying objects within CCD and digitized plate images. To exploit these catalogs, the system also provides tools to merge them into a large, complete database which may be easily queried and modified when new data or better methods of calibrating or classifying become available. The most innovative feature of SKICAT is the facility it provides to experiment with and apply the latest in machine learning technology to the tasks of catalog construction and analysis. SKICAT provides a unique environment for implementing these tools for any number of future scientific purposes. Initial scientific verification and performance tests have been made using galaxy counts and measurements of galaxy clustering from small subsets of the survey data, and a search for very high redshift quasars. All of the tests were successful, and produced new and interesting scientific results. Attachments to this report give detailed accounts of the technical aspects for multivariate statistical analysis of small and moderate-size data sets, called STATPROG. The package was tested extensively on a number of real scientific applications, and has produced real, published results.

The Sloan Digital Sky Survey Quasar Catalog: Fourteenth data release

NASA Astrophysics Data System (ADS)

Pâris, Isabelle; Petitjean, Patrick; Aubourg, Éric; Myers, Adam D.; Streblyanska, Alina; Lyke, Brad W.; Anderson, Scott F.; Armengaud, Éric; Bautista, Julian; Blanton, Michael R.; Blomqvist, Michael; Brinkmann, Jonathan; Brownstein, Joel R.; Brandt, William Nielsen; Burtin, Étienne; Dawson, Kyle; de la Torre, Sylvain; Georgakakis, Antonis; Gil-Marín, Héctor; Green, Paul J.; Hall, Patrick B.; Kneib, Jean-Paul; LaMassa, Stephanie M.; Le Goff, Jean-Marc; MacLeod, Chelsea; Mariappan, Vivek; McGreer, Ian D.; Merloni, Andrea; Noterdaeme, Pasquier; Palanque-Delabrouille, Nathalie; Percival, Will J.; Ross, Ashley J.; Rossi, Graziano; Schneider, Donald P.; Seo, Hee-Jong; Tojeiro, Rita; Weaver, Benjamin A.; Weijmans, Anne-Marie; Yèche, Christophe; Zarrouk, Pauline; Zhao, Gong-Bo

2018-05-01

We present the data release 14 Quasar catalog (DR14Q) from the extended Baryon Oscillation Spectroscopic Survey (eBOSS) of the Sloan Digital Sky Survey IV (SDSS-IV). This catalog includes all SDSS-IV/eBOSS objects that were spectroscopically targeted as quasar candidates and that are confirmed as quasars via a new automated procedure combined with a partial visual inspection of spectra, have luminosities Mi [z = 2] < -20.5 (in a Λ CDM cosmology with H0 = 70 km s-1 Mpc-1, Ω M =0.3, and Ω Λ = 0.7), and either display at least one emission line with a full width at half maximum larger than 500 km s-1 or, if not, have interesting/complex absorption features. The catalog also includes previously spectroscopically-confirmed quasars from SDSS-I, II, and III. The catalog contains 526 356 quasars (144 046 are new discoveries since the beginning of SDSS-IV) detected over 9376 deg2 (2044 deg2 having new spectroscopic data available) with robust identification and redshift measured by a combination of principal component eigenspectra. The catalog is estimated to have about 0.5% contamination. Redshifts are provided for the Mg II emission line. The catalog identifies 21 877 broad absorption line quasars and lists their characteristics. For each object, the catalog presents five-band (u, g, r, i, z) CCD-based photometry with typical accuracy of 0.03 mag. The catalog also contains X-ray, ultraviolet, near-infrared, and radio emission properties of the quasars, when available, from other large-area surveys. The calibrated digital spectra, covering the wavelength region 3610-10 140 Å at a spectral resolution in the range 1300 < R < 2500, can be retrieved from the SDSS Science Archiver Server. http://www.sdss.org/dr14/algorithms/qso_catalog

A Survey For TNOs Using the APS POSS I Database

NASA Astrophysics Data System (ADS)

Rhoads, E.

2005-05-01

The digitized first epoch Palomar Observatory Sky Survey (POSS I) was an ideal and unused archive for the purpose of data mining Trans-Neptunian Objects (TNOs). When accounting for overlap in TNO phase space and the area of the plates covered by stars and galaxies, the effective sky coverage area for this search was 4931 square degrees for Plutinos, and 4992 square degrees for classical TNOs. Using constraints based on the properties of known TNOs, computer codes were used to separate TNO candidates from millions of stars and galaxies. Lists of possible TNO, Centaur, and asteroid candidates were created. The results of this survey yielded 17 reliable TNOs and TNO candidates, including Pluto, Quaoar, and Varuna. In addition to the TNOs, 27 Centaur and 29 Asteroid candidates were found. The TNO Quaoar was pre-covered, and the Main Belt Asteroid (395) Delia was also recovered.

Cartography of Triangulum-Andromeda using SDSS stars

NASA Astrophysics Data System (ADS)

Perottoni, H. D.; Rocha-Pinto, H. J.; Girardi, L.; Balbinot, E.; Santiago, B. X.; Majewski, S. R.; Anders, F.; Da Costa, L.; Maia, M. A. G.

2018-01-01

The outer Galactic halo is home to a number of substructures which still have an uncertain origin, but most likely are remnants of former interactions between the Galaxy and its former satellites. Triangulum-Andromeda (TriAnd) is one of these halo substructures, found as an overdensity of Two Micron All Sky Survey (2MASS) M giants. We analysed the region of TriAnd using photometric data from the Ninth Data Release of Sloan Digital Sky Survey. By comparing the observations with simulations from the TRILEGAL Galactic model, we were able to identify and map several scattered overdensities of main-sequence stars that seem to be associated with TriAnd over a large area covering ∼500 deg2. One of these excesses may represent a new stellar overdensity. We also briefly discuss an alternative hypothesis, according to which TriAnd is one of the troughs of oscillation rings in the Galactic disc.

The Universe in Your City - Nineteen Capitals

NASA Astrophysics Data System (ADS)

Scarpa, D.; Más, A.

2010-10-01

The programme, The Universe in Your City - Nineteen Capitals, took us to each of Uruguay's nineteen provincial capitals. In each capital we erected our Kappa Crucis Digital Mobile Planetarium and were able to reach a wide range of children of school age, and especially children in "critical contexts" (i.e. socially and economically deprived children). We transported our equipment, together with the exhibition materials for the IYA2009 Cornerstone project, From Earth To The Universe - and set it up in open public spaces, staying in each location for one week and offering an average of nine daily 40-minute presentations. Each session featured information on Galileo Galilei's discoveries, the Uruguayan night sky and the cultural heritage provided by the sky. A record number of 46 428 people participated in the 884 sessions held between April and September; while many more simply visited the exhibition. This reflects the remarkable success of the project.

The Dynamic Radio Sky: Future Directions at cm/m-Wavelengths

NASA Astrophysics Data System (ADS)

Bower, Geoffrey C.; Cordes, J.; Croft, S.; Lazio, J.; Lorimer, D.; McLaughlin, M.

2009-01-01

The time domain of the radio wavelength sky has been only sparsely explored. Nevertheless, recent discoveries from limited surveys and serendipitous discoveries indicate that there is much to be found on timescales from nanoseconds to years and at wavelengths from meters to millimeters. These observations have revealed unexpected phenonmena such as rotating radio transients and coherent pulses from brown dwarfs. Additionally, archival studies have revealed an unknown class of radio transients without radio, optical, or high-energy hosts. The current generation of new meter- and centimeter-wave radio telescopes such as the MWA, LWA, PAPER, and ATA will exploit wide fields of view and flexible digital signal processing to systematically explore radio transient parameter space, as well as lay the scientific and technical foundation for the SKA. Known unknowns that will be the target of future transient surveys include orphan gamma-ray burst afterglows, radio supernovae, tidally-disrupted stars, flare stars, and magnetars.

Detection of massive tidal tails around the globular cluster Pal 5 with SDSS commissioning data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Odenkirchen, Michael; Grebel, Eva K.; Rockosi, Constance M.

2000-12-01

We report the discovery of two well-defined tidal tails emerging from the sparse remote globular cluster Palomar 5. These tails stretch out symmetrically to both sides of the cluster in the direction of constant Galactic latitude and subtend an angle of 2.6{sup o} on the sky. The tails have been detected in commissioning data of the Sloan Digital Sky Survey (SDSS), providing deep five-color photometry in a 2.5{sup o}-wide band along the equator. The stars in the tails make up a substantial part ({approx} 1/3) of the current total population of cluster stars in the magnitude interval 19.5 {le} i*more » {le} 22.0. This reveals that the cluster is subject to heavy mass loss. The orientation of the tails provides an important key for the determination of the cluster's Galactic orbit.« less

Developing Starlight connections with UNESCO sites through the Biosphere Smart

NASA Astrophysics Data System (ADS)

Marin, Cipriano

2015-08-01

The large number of UNESCO Sites around the world, in outstanding sites ranging from small islands to cities, makes it possible to build and share a comprehensive knowledge base on good practices and policies on the preservation of the night skies consistent with the protection of the associated scientific, natural and cultural values. In this context, the Starlight Initiative and other organizations such as IDA play a catalytic role in an essential international process to promote comprehensive, holistic approaches on dark sky preservation, astronomical observation, environmental protection, responsible lighting, sustainable energy, climate change and global sustainability.Many of these places have the potential to become models of excellence to foster the recovery of the dark skies and its defence against light pollution, included some case studies mentioned in the Portal to the Heritage of Astronomy.Fighting light pollution and recovering starry sky are already elements of a new emerging culture in biosphere reserves and world heritage sites committed to acting on climate change and sustainable development. Over thirty territories, including biosphere reserves and world heritage sites, have been developed successful initiatives to ensure night sky quality and promote sustainable lighting. Clear night skies also provide sustainable income opportunities as tourists and visitors are eagerly looking for sites with impressive night skies.Taking into account the high visibility and the ability of UNESCO sites to replicate network experiences, the Starlight Initiative has launched an action In cooperation with Biosphere Smart, aimed at promoting the Benchmark sites.Biosphere Smart is a global observatory created in partnership with UNESCO MaB Programme to share good practices, and experiences among UNESCO sites. The Benchmark sites window allows access to all the information of the most relevant astronomical heritage sites, dark sky protected areas and other places committed to the preservation of the values associated with the night sky. A new step ahead in our common task of protecting the starry skies at UNESCO sites.

The on-site quality-assurance system for Hyper Suprime-Cam: OSQAH

NASA Astrophysics Data System (ADS)

Furusawa, Hisanori; Koike, Michitaro; Takata, Tadafumi; Okura, Yuki; Miyatake, Hironao; Lupton, Robert H.; Bickerton, Steven; Price, Paul A.; Bosch, James; Yasuda, Naoki; Mineo, Sogo; Yamada, Yoshihiko; Miyazaki, Satoshi; Nakata, Fumiaki; Koshida, Shintaro; Komiyama, Yutaka; Utsumi, Yousuke; Kawanomoto, Satoshi; Jeschke, Eric; Noumaru, Junichi; Schubert, Kiaina; Iwata, Ikuru; Finet, Francois; Fujiyoshi, Takuya; Tajitsu, Akito; Terai, Tsuyoshi; Lee, Chien-Hsiu

2018-01-01

We have developed an automated quick data analysis system for data quality assurance (QA) for Hyper Suprime-Cam (HSC). The system was commissioned in 2012-2014, and has been offered for general observations, including the HSC Subaru Strategic Program, since 2014 March. The system provides observers with data quality information, such as seeing, sky background level, and sky transparency, based on quick analysis as data are acquired. Quick-look images and validation of image focus are also provided through an interactive web application. The system is responsible for the automatic extraction of QA information from acquired raw data into a database, to assist with observation planning, assess progress of all observing programs, and monitor long-term efficiency variations of the instrument and telescope. Enhancements of the system are being planned to facilitate final data analysis, to improve the HSC archive, and to provide legacy products for astronomical communities.

Analysis and Quality Assurance of the SKYMAP 4.0 Guidance and Tracking Star Catalog: The NASA SKY2000 Spacecraft Attitude Determination Star Catalog

NASA Technical Reports Server (NTRS)

Warren, Wayne H., Jr.

2001-01-01

An updated and improved NASA spacecraft attitude determination catalog, now called SKY2000, Version 3, has been prepared and quality assured. The highest priority goals were to replace the astrometric (positions and motions) and photometric (brightnesses and colors) data with the most recent and accurate data available. Quality assurance has been performed in a fairly straightforward manner, i.e., without extensive data checking and analysis, and many errors and Inconsistencies were corrected. Additional work should eventually be done on the variability and multiple-star data In the catalog, while certain other data can be significantly Improved. The current version of the catalog can be found at the GSFC Flight Dynamics website: http://cheli.gsfc.nasa.gov/dist/attitude/skymap.html. Supporting information and reference materials (published papers, format and data descriptions, etc.) can also be found at the website.

Explicit validation of a surface shortwave radiation balance model over snow-covered complex terrain

NASA Astrophysics Data System (ADS)

Helbig, N.; Löwe, H.; Mayer, B.; Lehning, M.

2010-09-01

A model that computes the surface radiation balance for all sky conditions in complex terrain is presented. The spatial distribution of direct and diffuse sky radiation is determined from observations of incident global radiation, air temperature, and relative humidity at a single measurement location. Incident radiation under cloudless sky is spatially derived from a parameterization of the atmospheric transmittance. Direct and diffuse sky radiation for all sky conditions are obtained by decomposing the measured global radiation value. Spatial incident radiation values under all atmospheric conditions are computed by adjusting the spatial radiation values obtained from the parametric model with the radiation components obtained from the decomposition model at the measurement site. Topographic influences such as shading are accounted for. The radiosity approach is used to compute anisotropic terrain reflected radiation. Validations of the shortwave radiation balance model are presented in detail for a day with cloudless sky. For a day with overcast sky a first validation is presented. Validation of a section of the horizon line as well as of individual radiation components is performed with high-quality measurements. A new measurement setup was designed to determine terrain reflected radiation. There is good agreement between the measurements and the modeled terrain reflected radiation values as well as with incident radiation values. A comparison of the model with a fully three-dimensional radiative transfer Monte Carlo model is presented. That validation reveals a good agreement between modeled radiation values.

ELUCID—Exploring the Local Universe with the reConstructed Initial Density Field. II. Reconstruction Diagnostics, Applied to Numerical Halo Catalogs

NASA Astrophysics Data System (ADS)

Tweed, Dylan; Yang, Xiaohu; Wang, Huiyuan; Cui, Weiguang; Zhang, Youcai; Li, Shijie; Jing, Y. P.; Mo, H. J.

2017-05-01

The ELUCID project aims to build a series of realistic cosmological simulations that reproduce the spatial and mass distributions of the galaxies as observed in the Sloan Digital Sky Survey. This requires powerful reconstruction techniques to create constrained initial conditions (ICs). We test the reconstruction method by applying it to several N-body simulations. We use two medium-resolution simulations, which each produced three additional constrained N-body simulations. We compare the resulting friend-of-friend catalogs by using the particle indexes as tracers, and quantify the quality of the reconstruction by varying the main smoothing parameter. The cross-identification method we use proves to be efficient, and the results suggest that the most massive reconstructed halos are effectively traced from the same Lagrangian regions in the ICs. A preliminary time-dependence analysis indicates that high-mass-end halos converge only at a redshift close to the reconstruction redshift. This suggests that, for earlier snapshots, only collections of progenitors may be effectively cross-identified.

Pluto Haze

NASA Image and Video Library

2015-09-10

Two different versions of an image of Pluto's haze layers, taken by New Horizons as it looked back at Pluto's dark side nearly 16 hours after close approach, from a distance of 480,000 miles (770,000 kilometers), at a phase angle of 166 degrees. Pluto's north is at the top, and the sun illuminates Pluto from the upper right. These images are much higher quality than the digitally compressed images of Pluto's haze downlinked and released shortly after the July 14 encounter, and allow many new details to be seen. The left version has had only minor processing, while the right version has been specially processed to reveal a large number of discrete haze layers in the atmosphere. In the left version, faint surface details on the narrow sunlit crescent are seen through the haze in the upper right of Pluto's disk, and subtle parallel streaks in the haze may be crepuscular rays- shadows cast on the haze by topography such as mountain ranges on Pluto, similar to the rays sometimes seen in the sky after the sun sets behind mountains on Earth. http://photojournal.jpl.nasa.gov/catalog/PIA19880

Pathfinder, Volume 7, Number 5, September/October 2009. Charting the Sea and Sky

DTIC Science & Technology

2009-10-01

During the six-month season, ski-equipped LC-130s, the polar version of the C-130 Hercules transport plane, flew more than 8.7 million pounds of...collaborate closely with the Space and Naval Warfare Systems Command (SPAWAR), Office of Polar Programs; the Federal Avia- tion Administration (FAA...only worldwide vector chart coverage. Recently, the Navy implemented polar navigation using NGA charts and is now capable of true worldwide digital

Making the most of missing values : object clustering with partial data in astronomy

NASA Technical Reports Server (NTRS)

Wagstaff, Kiri L.; Laidler, Victoria G.

2004-01-01

We demonstrate a clustering analysis algorithm, KSC, that a) uses all observed values and b) does not discard the partially observed objects. KSC uses soft constraints defined by the fully observed objects to assist in the grouping of objects with missing values. We present an analysis of objects taken from the Sloan Digital Sky Survey to demonstrate how imputing the values can be misleading and why the KSC approach can produce more appropriate results.

The Three-Dimensional Power Spectrum Of Galaxies from the Sloan Digital Sky Survey

DTIC Science & Technology

2004-05-10

aspects of the three-dimensional clustering of a much larger data set involving over 200,000 galaxies with redshifts. This paper is focused on measuring... papers , we will constrain galaxy bias empirically by using clustering measurements on smaller scales (e.g., I. Zehavi et al. 2004, in preparation...minimum-variance measurements in 22 k-bands of both the clustering power and its anisotropy due to redshift-space distortions, with narrow and well

The Eighth Data Release Of The Sloan Digital Sky Survey: First Data From SDSS-3

DTIC Science & Technology

2011-04-01

Sunspot, NM 88349, USA 14 Center for Cosmology and Particle Physics, New York University, 4 Washington Place, New York, NY 10003, USA 15 Department of...Park, PA 16802, USA 18 Institute of Cosmology and Gravitation (ICG), Dennis Sciama Building, Burnaby Road, University of Portsmouth, Portsmouth, PO1 3FX... Cosmology , Carnegie Mellon University, Pittsburgh, P.A. 15213, USA 26 Yale Center for Astronomy and Astrophysics, Yale University, New Haven, CT 06520

A model for a PC-based, universal-format, multimedia digitization system: moving beyond the scanner.

PubMed

McEachen, James C; Cusack, Thomas J; McEachen, John C

2003-08-01

Digitizing images for use in case presentations based on hardcopy films, slides, photographs, negatives, books, and videos can present a challenging task. Scanners and digital cameras have become standard tools of the trade. Unfortunately, use of these devices to digitize multiple images in many different media formats can be a time-consuming and in some cases unachievable process. The authors' goal was to create a PC-based solution for digitizing multiple media formats in a timely fashion while maintaining adequate image presentation quality. The authors' PC-based solution makes use of off-the-shelf hardware applications to include a digital document camera (DDC), VHS video player, and video-editing kit. With the assistance of five staff radiologists, the authors examined the quality of multiple image types digitized with this equipment. The authors also quantified the speed of digitization of various types of media using the DDC and video-editing kit. With regard to image quality, the five staff radiologists rated the digitized angiography, CT, and MR images as adequate to excellent for use in teaching files and case presentations. With regard to digitized plain films, the average rating was adequate. As for performance, the authors recognized a 68% improvement in the time required to digitize hardcopy films using the DDC instead of a professional quality scanner. The PC-based solution provides a means for digitizing multiple images from many different types of media in a timely fashion while maintaining adequate image presentation quality.

Photometric properties of intermediate-redshift Type Ia supernovae observed by the Sloan Digital Sky Survey-II Supernova Survey

DOE PAGES

Takanashi, N.; Doi, M.; Yasuda, N.; ...

2016-12-06

We have analyzed multi-band light curves of 328 intermediate redshift (0.05 <= z < 0.24) type Ia supernovae (SNe Ia) observed by the Sloan Digital Sky Survey-II Supernova Survey (SDSS-II SN Survey). The multi-band light curves were parameterized by using the Multi-band Stretch Method, which can simply parameterize light curve shapes and peak brightness without dust extinction models. We found that most of the SNe Ia which appeared in red host galaxies (u - r > 2.5) don't have a broad light curve width and the SNe Ia which appeared in blue host galaxies (u - r < 2.0) havemore » a variety of light curve widths. The Kolmogorov-Smirnov test shows that the colour distribution of SNe Ia appeared in red / blue host galaxies is different (significance level of 99.9%). We also investigate the extinction law of host galaxy dust. As a result, we find the value of Rv derived from SNe Ia with medium light curve width is consistent with the standard Galactic value. On the other hand, the value of Rv derived from SNe Ia that appeared in red host galaxies becomes significantly smaller. Furthermore, these results indicate that there may be two types of SNe Ia with different intrinsic colours, and they are obscured by host galaxy dust with two different properties.« less

Photometric properties of intermediate-redshift Type Ia supernovae observed by the Sloan Digital Sky Survey-II Supernova Survey

DOE Office of Scientific and Technical Information (OSTI.GOV)

Takanashi, N.; Doi, M.; Yasuda, N.

We have analyzed multi-band light curves of 328 intermediate redshift (0.05 <= z < 0.24) type Ia supernovae (SNe Ia) observed by the Sloan Digital Sky Survey-II Supernova Survey (SDSS-II SN Survey). The multi-band light curves were parameterized by using the Multi-band Stretch Method, which can simply parameterize light curve shapes and peak brightness without dust extinction models. We found that most of the SNe Ia which appeared in red host galaxies (u - r > 2.5) don't have a broad light curve width and the SNe Ia which appeared in blue host galaxies (u - r < 2.0) havemore » a variety of light curve widths. The Kolmogorov-Smirnov test shows that the colour distribution of SNe Ia appeared in red / blue host galaxies is different (significance level of 99.9%). We also investigate the extinction law of host galaxy dust. As a result, we find the value of Rv derived from SNe Ia with medium light curve width is consistent with the standard Galactic value. On the other hand, the value of Rv derived from SNe Ia that appeared in red host galaxies becomes significantly smaller. Furthermore, these results indicate that there may be two types of SNe Ia with different intrinsic colours, and they are obscured by host galaxy dust with two different properties.« less

The Ensemble Photometric Variability of Over 105 Quasars in the Dark Energy Camera Legacy Survey and the Sloan Digital Sky Survey

NASA Astrophysics Data System (ADS)

Li, Zefeng; McGreer, Ian D.; Wu, Xue-Bing; Fan, Xiaohui; Yang, Qian

2018-07-01

We present the ensemble variability analysis results of quasars using the Dark Energy Camera Legacy Survey (DECaLS) and the Sloan Digital Sky Survey (SDSS) quasar catalogs. Our data set includes 119,305 quasars with redshifts up to 4.89. Combining the two data sets provides a 15 year baseline and permits the analysis of the long timescale variability. Adopting a power-law form for the variability structure function, V=A{(t/1{years})}γ , we use the multidimensional parametric fitting to explore the relationships between the quasar variability amplitude and a wide variety of quasar properties, including redshift (positive), bolometric luminosity (negative), rest-frame wavelength (negative), and black hole mass (uncertain). We also find that γ can be also expressed as a function of redshift (negative), bolometric luminosity (positive), rest-frame wavelength (positive), and black hole mass (positive). Tests of the fitting significance with the bootstrap method show that, even with such a large quasar sample, some correlations are marginally significant. The typical value of γ for the entire data set is ≳0.25, consistent with the results in previous studies on both the quasar ensemble variability and the structure function. A significantly negative correlation between the variability amplitude and the Eddington ratio is found, which may be explained as an effect of accretion disk instability.

A New Approach to Galaxy Morphology. I. Analysis of the Sloan Digital Sky Survey Early Data Release

NASA Astrophysics Data System (ADS)

Abraham, Roberto G.; van den Bergh, Sidney; Nair, Preethi

2003-05-01

In this paper we present a new statistic for quantifying galaxy morphology based on measurements of the Gini coefficient of galaxy light distributions. This statistic is easy to measure and is commonly used in econometrics to measure how wealth is distributed in human populations. When applied to galaxy images, the Gini coefficient provides a quantitative measure of the inequality with which a galaxy's light is distributed among its constituent pixels. We measure the Gini coefficient of local galaxies in the Early Data Release of the Sloan Digital Sky Survey and demonstrate that this quantity is closely correlated with measurements of central concentration, but with significant scatter. This scatter is almost entirely due to variations in the mean surface brightness of galaxies. By exploring the distribution of galaxies in the three-dimensional parameter space defined by the Gini coefficient, central concentration, and mean surface brightness, we show that all nearby galaxies lie on a well-defined two-dimensional surface (a slightly warped plane) embedded within a three-dimensional parameter space. By associating each galaxy sample with the equation of this plane, we can encode the morphological composition of the entire SDSS g*-band sample using the following three numbers: {22.451, 5.366, 7.010}. The i*-band sample is encoded as {22.149, 5.373, and 7.627}.

Galaxies in the Illustris simulation as seen by the Sloan Digital Sky Survey - II. Size-luminosity relations and the deficit of bulge-dominated galaxies in Illustris at low mass

NASA Astrophysics Data System (ADS)

Bottrell, Connor; Torrey, Paul; Simard, Luc; Ellison, Sara L.

2017-05-01

The interpretive power of the newest generation of large-volume hydrodynamical simulations of galaxy formation rests upon their ability to reproduce the observed properties of galaxies. In this second paper in a series, we employ bulge+disc decompositions of realistic dust-free galaxy images from the Illustris simulation in a consistent comparison with galaxies from the Sloan Digital Sky Survey (SDSS). Examining the size-luminosity relations of each sample, we find that galaxies in Illustris are roughly twice as large and 0.7 mag brighter on average than galaxies in the SDSS. The trend of increasing slope and decreasing normalization of size-luminosity as a function of bulge fraction is qualitatively similar to observations. However, the size-luminosity relations of Illustris galaxies are quantitatively distinguished by higher normalizations and smaller slopes than for real galaxies. We show that this result is linked to a significant deficit of bulge-dominated galaxies in Illustris relative to the SDSS at stellar masses log M_{\\star }/M_{⊙}≲ 11. We investigate this deficit by comparing bulge fraction estimates derived from photometry and internal kinematics. We show that photometric bulge fractions are systematically lower than the kinematic fractions at low masses, but with increasingly good agreement as the stellar mass increases.

On Identifying Clusters Within the C-type Asteroids of the Sloan Digital Sky Survey

NASA Astrophysics Data System (ADS)

Poole, Renae; Ziffer, J.; Harvell, T.

2012-10-01

We applied AutoClass, a data mining technique based upon Bayesian Classification, to C-group asteroid colors in the Sloan Digital Sky Survey (SDSS). Previous taxonomic studies relied mostly on Principal Component Analysis (PCA) to differentiate asteroids within the C-group (e.g. B, G, F, Ch, Cg and Cb). AutoClass's advantage is that it calculates the most probable classification for us, removing the human factor from this part of the analysis. In our results, AutoClass divided the C-groups into two large classes and six smaller classes. The two large classes (n=4974 and 2033, respectively) display distinct regions with some overlap in color-vs-color plots. Each cluster's average spectrum is compared to 'typical' spectra of the C-group subtypes as defined by Tholen (1989) and each cluster's members are evaluated for consistency with previous taxonomies. Of the 117 asteroids classified as B-type in previous taxonomies, only 12 were found with SDSS colors that matched our criteria of having less than 0.1 magnitude error in u and 0.05 magnitude error in g, r, i, and z colors. Although this is a relatively small group, 11 of the 12 B-types were placed by AutoClass in the same cluster. By determining the C-group sub-classifications in the large SDSS database, this research furthers our understanding of the stratigraphy and composition of the main-belt.

Galaxy pairs in the Sloan Digital Sky Survey - XI. A new method for measuring the influence of the closest companion out to wide separations

NASA Astrophysics Data System (ADS)

Patton, David R.; Qamar, Farid D.; Ellison, Sara L.; Bluck, Asa F. L.; Simard, Luc; Mendel, J. Trevor; Moreno, Jorge; Torrey, Paul

2016-09-01

We describe a statistical approach for measuring the influence that a galaxy's closest companion has on the galaxy's properties out to arbitrarily wide separations. We begin by identifying the closest companion for every galaxy in a large spectroscopic sample of Sloan Digital Sky Survey galaxies. We then characterize the local environment of each galaxy by using the number of galaxies within 2 Mpc and by determining the isolation of the galaxy pair from other neighbouring galaxies. We introduce a sophisticated algorithm for creating a statistical control sample for each galaxy, matching on stellar mass, redshift, local density and isolation. Unlike traditional studies of close galaxy pairs, this approach is effective in a wide range of environments, regardless of how faraway the closest companion is (although a very distant closest companion is unlikely to have a measurable influence on the galaxy in question). We apply this methodology to measurements of galaxy asymmetry, and find that the presence of nearby companions drives a clear enhancement in galaxy asymmetries. The asymmetry excess peaks at the smallest projected separations (<10 kpc), where the mean asymmetry is enhanced by a factor of 2.0 ± 0.2. Enhancements in mean asymmetry decline as pair separation increases, but remain statistically significant (1σ-2σ) out to projected separations of at least 50 kpc.

C IV BROAD ABSORPTION LINE ACCELERATION IN SLOAN DIGITAL SKY SURVEY QUASARS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grier, C. J.; Brandt, W. N.; Trump, J. R.

2016-06-20

We present results from the largest systematic investigation of broad absorption line (BAL) acceleration to date. We use spectra of 140 quasars from three Sloan Digital Sky Survey programs to search for global velocity offsets in BALs over timescales of ≈2.5–5.5 years in the quasar rest frame. We carefully select acceleration candidates by requiring monolithic velocity shifts over the entire BAL trough, avoiding BALs with velocity shifts that might be caused by profile variability. The C iv BALs of two quasars show velocity shifts consistent with the expected signatures of BAL acceleration, and the BAL of one quasar shows amore » velocity-shift signature of deceleration. In our two acceleration candidates, we see evidence that the magnitude of the acceleration is not constant over time; the magnitudes of the change in acceleration for both acceleration candidates are difficult to produce with a standard disk-wind model or via geometric projection effects. We measure upper limits to acceleration and deceleration for 76 additional BAL troughs and find that the majority of BALs are stable to within about 3% of their mean velocities. The lack of widespread acceleration/deceleration could indicate that the gas producing most BALs is located at large radii from the central black hole and/or is not currently strongly interacting with ambient material within the host galaxy along our line of sight.« less

Enabling Astronony Research in High Schools with the START Collaboratory

NASA Astrophysics Data System (ADS)

Greenberg, G. J.; Pennypacker, C. R.

2005-12-01

The START Collaboratory is a three-year, NSF funded project to create a Web-based national astronomy research collaboratory for high school students that will bring authentic scientific research to classrooms across the country. The project brings together the resources and experience of Hands-On Universe at the University of California at Berkeley, the Sloan Digital Sky Survey / National Virtual Observatory at Johns Hopkins University and the Northwestern University Collaboratory Project. The START Collaboratory seamlessly integrates access to gigabytes of searchable data and images from the Sloan Digital Sky Survey and the NVO into Web-based research notebooks and research reports that can be shared and discussed online. Requests for observations can be made through the START Telescope Request Broker. These observations can be viewed with the START Web Visualization Tool for visualization and measurement of FITS files. The project has developed a set of research scenarios to introduce students to the resources and tools available through the START Collaboratory, and to provide a model for network-based collaboration that engages students, teachers and professional scientists. Great attention has been paid to ensuring that the research scenarios result in accurate and authentic research products that are of real interest to working astronomers. In this panel presentation, we will describe the educational benefits and opportunities being seen in pilot testing with teachers and students, and in preparations for a teacher professional development project with the Adler Planetarium.

Detecting effects of filaments on galaxy properties in the Sloan Digital Sky Survey III

NASA Astrophysics Data System (ADS)

Chen, Yen-Chi; Ho, Shirley; Mandelbaum, Rachel; Bahcall, Neta A.; Brownstein, Joel R.; Freeman, Peter E.; Genovese, Christopher R.; Schneider, Donald P.; Wasserman, Larry

2017-04-01

We study the effects of filaments on galaxy properties in the Sloan Digital Sky Survey (SDSS) Data Release 12 using filaments from the 'Cosmic Web Reconstruction' catalogue, a publicly available filament catalogue for SDSS. Since filaments are tracers of medium- to high-density regions, we expect that galaxy properties associated with the environment are dependent on the distance to the nearest filament. Our analysis demonstrates that a red galaxy or a high-mass galaxy tends to reside closer to filaments than a blue or low-mass galaxy. After adjusting the effect from stellar mass, on average, early-forming galaxies or large galaxies have a shorter distance to filaments than late-forming galaxies or small galaxies. For the main galaxy sample, all signals are very significant (>6σ). For the LOWZ and CMASS sample, the stellar mass and size are significant (>2σ). The filament effects we observe persist until z = 0.7 (the edge of the CMASS sample). Comparing our results to those using the galaxy distances from redMaPPer galaxy clusters as a reference, we find a similar result between filaments and clusters. Moreover, we find that the effect of clusters on the stellar mass of nearby galaxies depends on the galaxy's filamentary environment. Our findings illustrate the strong correlation of galaxy properties with proximity to density ridges, strongly supporting the claim that density ridges are good tracers of filaments.

Galaxy-scale Bars in Late-type Sloan Digital Sky Survey Galaxies Do Not Influence the Average Accretion Rates of Supermassive Black Holes

NASA Astrophysics Data System (ADS)

Goulding, A. D.; Matthaey, E.; Greene, J. E.; Hickox, R. C.; Alexander, D. M.; Forman, W. R.; Jones, C.; Lehmer, B. D.; Griffis, S.; Kanek, S.; Oulmakki, M.

2017-07-01

Galaxy-scale bars are expected to provide an effective means for driving material toward the central region in spiral galaxies, and possibly feeding supermassive black holes (BHs). Here we present a statistically complete study of the effect of bars on average BH accretion. From a well-selected sample of 50,794 spiral galaxies (with {M}* ˜ 0.2{--}30× {10}10 {M}⊙ ) extracted from the Sloan Digital Sky Survey Galaxy Zoo 2 project, we separate those sources considered to contain galaxy-scale bars from those that do not. Using archival data taken by the Chandra X-ray Observatory, we identify X-ray luminous ({L}{{X}}≳ {10}41 {erg} {{{s}}}-1) active galactic nuclei and perform an X-ray stacking analysis on the remaining X-ray undetected sources. Through X-ray stacking, we derive a time-averaged look at accretion for galaxies at fixed stellar mass and star-formation rate, finding that the average nuclear accretion rates of galaxies with bar structures are fully consistent with those lacking bars ({\\dot{M}}{acc}≈ 3× {10}-5 {M}⊙ yr-1). Hence, we robustly conclude that large-scale bars have little or no effect on the average growth of BHs in nearby (z< 0.15) galaxies over gigayear timescales.

The eleventh and twelfth data releases of the Sload Digital Sky Survey: final data from SDSS-III

DOE PAGES

Alam, S.; Slosar, A.; Albareti, F. D.; ...

2015-07-01

The third generation of the Sloan Digital Sky Survey (SDSS-III) took data from 2008 to 2014 using the original SDSS wide-field imager, the original and an upgraded multi-object fiber-fed optical spectrograph, a new near-infrared high-resolution spectrograph, and a novel optical interferometer. All of the data from SDSS-III are now made public. In particular, this paper describes Data Release 11 (DR11) including all data acquired through 2013 July, and Data Release 12 (DR12) adding data acquired through 2014 July (including all data included in previous data releases), marking the end of SDSS-III observing. Relative to our previous public release (DR10), DR12more » adds one million new spectra of galaxies and quasars from the Baryon Oscillation Spectroscopic Survey (BOSS) over an additional 3000 deg 2 of sky, more than triples the number of H-band spectra of stars as part of the Apache Point Observatory (APO) Galactic Evolution Experiment (APOGEE), and includes repeated accurate radial velocity measurements of 5500 stars from the Multi-object APO Radial Velocity Exoplanet Large-area Survey (MARVELS). The APOGEE outputs now include the measured abundances of 15 different elements for each star. In total, SDSS-III added 5200 deg 2 of ugriz imaging; 155,520 spectra of 138,099 stars as part of the Sloan Exploration of Galactic Understanding and Evolution 2 (SEGUE-2) survey; 2,497,484 BOSS spectra of 1,372,737 galaxies, 294,512 quasars, and 247,216 stars over 9376 deg 2; 618,080 APOGEE spectra of 156,593 stars; and 197,040 MARVELS spectra of 5513 stars. Since its first light in 1998, SDSS has imaged over 1/3 of the Celestial sphere in five bands and obtained over five million astronomical spectra.« less

Gargantuan Super Spiral Galaxies Loom Large in the Cosmos

NASA Image and Video Library

2016-03-17

In archived NASA data, researchers have discovered "super spiral" galaxies that dwarf our own spiral galaxy, the Milky Way, and compete in size and brightness with the largest galaxies in the universe. The unprecedented galaxies have long hidden in plain sight by mimicking the appearance of typical spirals. Three examples of super spirals are presented here in images taken by the Sloan Digital Sky Survey. The super spiral on the left (Figure 1), catalogued as 2MASX J08542169+0449308, contains two galactic nuclei, instead of just the usual one, and thus looks like two eggs frying in a pan. The central image (Figure 2) shows a super spiral designated 2MASX J16014061+2718161, and it also contains the double nuclei. On the right (Figure 3), a huge galaxy with the moniker SDSS J094700.08+254045.7 stands as one of the biggest and brightest super spirals. The mega-galaxy's starry disk and spiral arms stretch about 320,000 light-years across, or more than three times the breadth of the Milky Way. These double nuclei, which are known to result from the recent merger of two galaxies, could offer a vital hint about the potential origin of super spirals. Researchers speculate that a special merger involving two, gas-rich spiral galaxies could see their pooled gases settle down into a new, larger stellar disk -- presto, a super spiral. The super spirals were discovered using the NASA/IPAC Extragalactic Database, or NED, an online repository containing information on over 100 million galaxies. NED brings together a wealth of data from many different projects, including ultraviolet light observations from the Galaxy Evolution Explorer, visible light from Sloan Digital Sky Survey, infrared light from the 2-Micron All-Sky Survey, and links to data from other missions such as NASA's Spitzer Space Telescope and Wide-Field Infrared Survey Explorer, or WISE. http://photojournal.jpl.nasa.gov/catalog/PIA20064

The eleventh and twelfth data release of the Sloan Digital Sky Survey: Final data from SDSS-III

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alam, Shadab; Albareti, Franco D.; Prieto, Carlos Allende

2015-07-20

The third generation of the Sloan Digital Sky Survey (SDSS-III) took data from 2008 to 2014 using the original SDSS wide-field imager, the original and an upgraded multi-object fiber-fed optical spectrograph, a new near-infrared high-resolution spectrograph, and a novel optical interferometer. All of the data from SDSS-III are now made public. In particular, this paper describes Data Release 11 (DR11) including all data acquired through 2013 July, and Data Release 12 (DR12) adding data acquired through 2014 July (including all data included in previous data releases), marking the end of SDSS-III observing. Relative to our previous public release (DR10), DR12more » adds one million new spectra of galaxies and quasars from the Baryon Oscillation Spectroscopic Survey (BOSS) over an additional 3000 deg 2 of sky, more than triples the number of H-band spectra of stars as part of the Apache Point Observatory (APO) Galactic Evolution Experiment (APOGEE), and includes repeated accurate radial velocity measurements of 5500 stars from the Multi-object APO Radial Velocity Exoplanet Large-area Survey (MARVELS). The APOGEE outputs now include the measured abundances of 15 different elements for each star. In total, SDSS-III added 5200 deg 2 of ugriz imaging; 155,520 spectra of 138,099 stars as part of the Sloan Exploration of Galactic Understanding and Evolution 2 (SEGUE-2) survey; 2,497,484 BOSS spectra of 1,372,737 galaxies, 294,512 quasars, and 247,216 stars over 9376 deg 2; 618,080 APOGEE spectra of 156,593 stars; and 197,040 MARVELS spectra of 5513 stars. Since its first light in 1998, SDSS has imaged over 1/3 of the Celestial sphere in five bands and obtained over five million astronomical spectra.« less

THE ELEVENTH AND TWELFTH DATA RELEASES OF THE SLOAN DIGITAL SKY SURVEY: FINAL DATA FROM SDSS-III

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alam, Shadab; Albareti, Franco D.; Prieto, Carlos Allende

2015-07-15

The third generation of the Sloan Digital Sky Survey (SDSS-III) took data from 2008 to 2014 using the original SDSS wide-field imager, the original and an upgraded multi-object fiber-fed optical spectrograph, a new near-infrared high-resolution spectrograph, and a novel optical interferometer. All of the data from SDSS-III are now made public. In particular, this paper describes Data Release 11 (DR11) including all data acquired through 2013 July, and Data Release 12 (DR12) adding data acquired through 2014 July (including all data included in previous data releases), marking the end of SDSS-III observing. Relative to our previous public release (DR10), DR12more » adds one million new spectra of galaxies and quasars from the Baryon Oscillation Spectroscopic Survey (BOSS) over an additional 3000 deg{sup 2} of sky, more than triples the number of H-band spectra of stars as part of the Apache Point Observatory (APO) Galactic Evolution Experiment (APOGEE), and includes repeated accurate radial velocity measurements of 5500 stars from the Multi-object APO Radial Velocity Exoplanet Large-area Survey (MARVELS). The APOGEE outputs now include the measured abundances of 15 different elements for each star. In total, SDSS-III added 5200 deg{sup 2} of ugriz imaging; 155,520 spectra of 138,099 stars as part of the Sloan Exploration of Galactic Understanding and Evolution 2 (SEGUE-2) survey; 2,497,484 BOSS spectra of 1,372,737 galaxies, 294,512 quasars, and 247,216 stars over 9376 deg{sup 2}; 618,080 APOGEE spectra of 156,593 stars; and 197,040 MARVELS spectra of 5513 stars. Since its first light in 1998, SDSS has imaged over 1/3 of the Celestial sphere in five bands and obtained over five million astronomical spectra.« less

Color-Space Outliers in DPOSS: Quasars and Peculiar Objects

NASA Astrophysics Data System (ADS)

Djorgovski, S. G.; Gal, R. R.; Mahabal, A.; Brunner, R.; Castro, S. M.; Odewahn, S. C.; de Carvalho, R. R.; DPOSS Team

2000-12-01

The processing of DPOSS, a digital version of the POSS-II sky atlas, is now nearly complete. The resulting Palomar--Norris Sky Catalog (PNSC) is expected to contain > 5 x 107 galaxies and > 109 stars, including large numbers of quasars and other unresolved sources. For objects morphologically classified as stellar (i.e., PSF-like), colors and magnitudes provide the only additional source of discriminating information. We investigate the distribution of objects in the parameter space of (g-r) and (r-i) colors as a function of magnitude. Normal stars form a well-defined (temperature) sequence in this parameter space, and we explore the nature of the objects which deviate significantly from this stellar locus. The causes of the deviations include: non-thermal or peculiar spectra, interagalactic absorption (for high-z quasars), presence of strong emission lines in one or more of the bandpasses, or strong variability (because the plates are taken at widely separated epochs). In addition to minor contamination by misclassified compact galaxies, we find the following: (1) Quasars at z > 4; to date, ~ 100 of these objects have been found, and used for a variety of follow-up studies. They are made publicly available immediately after discovery, through http://astro.caltech.edu/ ~george/z4.qsos. (2) Type-2 quasars in the redshift interval z ~ 0.31 - 0.38. (3) Other quasars, starburst and emission-line galaxies, and emission-line stars. (4) Objects with highly peculiar spectra, some or all of which may be rare subtypes of BAL QSOs. (5) Highly variable stars and optical transients, some of which may be GRB ``orphan afterglows''. To date, systematic searches have been made only for (1) and (2); other types of objects were found serendipitously. However, we plan to explore systematically all of the statistically significant outliers in this parameter space. This illustrates the potential of large digital sky surveys for discovery of rare types of objects, both known (e.g., high-z quasars) and as yet unknown.

ISS images for Observatory protection

NASA Astrophysics Data System (ADS)

Sánchez de Miguel, Alejandro; Zamorano, Jaime

2015-08-01

Light pollution is the main factor of degradation of the astronomical quality of the sky along the history. Astronomical observatories have been monitoring how the brightness of the sky varies using photometric measures of the night sky brightness mainly at zenith. Since the sky brightness depends in other factors such as sky glow, aerosols, solar activity and the presence of celestial objects, the continuous increase of light pollution in these enclaves is difficult to trace except when it is too late.Using models of light dispersion on the atmosphere one can determine which light pollution sources are increasing the sky brightness at the observatories. The input satellite data has been provided by DMSP/OLS and SNPP/VIIRS. Unfortunately their panchromatic bands (color blinded) are not useful to detect in which extension the increase is due to the dramatic change produced by the irruption of LED technology in outdoor lighting. The only instrument in the space that is able to distinguish between the various lighting technologies are the DSLR cameras used by the astronauts onboard the ISS.Current status for some astronomical observatories that have been imaged from the ISS is presented. We are planning to send an official request to NASA with a plan to get images for the most important astronomical observatories. We ask support for this proposal by the astronomical community and especially by the US-based researchers.

Towards a Visual Quality Metric for Digital Video

NASA Technical Reports Server (NTRS)

Watson, Andrew B.

1998-01-01

The advent of widespread distribution of digital video creates a need for automated methods for evaluating visual quality of digital video. This is particularly so since most digital video is compressed using lossy methods, which involve the controlled introduction of potentially visible artifacts. Compounding the problem is the bursty nature of digital video, which requires adaptive bit allocation based on visual quality metrics. In previous work, we have developed visual quality metrics for evaluating, controlling, and optimizing the quality of compressed still images. These metrics incorporate simplified models of human visual sensitivity to spatial and chromatic visual signals. The challenge of video quality metrics is to extend these simplified models to temporal signals as well. In this presentation I will discuss a number of the issues that must be resolved in the design of effective video quality metrics. Among these are spatial, temporal, and chromatic sensitivity and their interactions, visual masking, and implementation complexity. I will also touch on the question of how to evaluate the performance of these metrics.

Automated Assessment of Visual Quality of Digital Video

NASA Technical Reports Server (NTRS)

Watson, Andrew B.; Ellis, Stephen R. (Technical Monitor)

1997-01-01

The advent of widespread distribution of digital video creates a need for automated methods for evaluating visual quality of digital video. This is particularly so since most digital video is compressed using lossy methods, which involve the controlled introduction of potentially visible artifacts. Compounding the problem is the bursty nature of digital video, which requires adaptive bit allocation based on visual quality metrics. In previous work, we have developed visual quality metrics for evaluating, controlling, and optimizing the quality of compressed still images[1-4]. These metrics incorporate simplified models of human visual sensitivity to spatial and chromatic visual signals. The challenge of video quality metrics is to extend these simplified models to temporal signals as well. In this presentation I will discuss a number of the issues that must be resolved in the design of effective video quality metrics. Among these are spatial, temporal, and chromatic sensitivity and their interactions, visual masking, and implementation complexity. I will also touch on the question of how to evaluate the performance of these metrics.

DESCQA: An Automated Validation Framework for Synthetic Sky Catalogs

NASA Astrophysics Data System (ADS)

Mao, Yao-Yuan; Kovacs, Eve; Heitmann, Katrin; Uram, Thomas D.; Benson, Andrew J.; Campbell, Duncan; Cora, Sofía A.; DeRose, Joseph; Di Matteo, Tiziana; Habib, Salman; Hearin, Andrew P.; Bryce Kalmbach, J.; Krughoff, K. Simon; Lanusse, François; Lukić, Zarija; Mandelbaum, Rachel; Newman, Jeffrey A.; Padilla, Nelson; Paillas, Enrique; Pope, Adrian; Ricker, Paul M.; Ruiz, Andrés N.; Tenneti, Ananth; Vega-Martínez, Cristian A.; Wechsler, Risa H.; Zhou, Rongpu; Zu, Ying; The LSST Dark Energy Science Collaboration

2018-02-01

The use of high-quality simulated sky catalogs is essential for the success of cosmological surveys. The catalogs have diverse applications, such as investigating signatures of fundamental physics in cosmological observables, understanding the effect of systematic uncertainties on measured signals and testing mitigation strategies for reducing these uncertainties, aiding analysis pipeline development and testing, and survey strategy optimization. The list of applications is growing with improvements in the quality of the catalogs and the details that they can provide. Given the importance of simulated catalogs, it is critical to provide rigorous validation protocols that enable both catalog providers and users to assess the quality of the catalogs in a straightforward and comprehensive way. For this purpose, we have developed the DESCQA framework for the Large Synoptic Survey Telescope Dark Energy Science Collaboration as well as for the broader community. The goal of DESCQA is to enable the inspection, validation, and comparison of an inhomogeneous set of synthetic catalogs via the provision of a common interface within an automated framework. In this paper, we present the design concept and first implementation of DESCQA. In order to establish and demonstrate its full functionality we use a set of interim catalogs and validation tests. We highlight several important aspects, both technical and scientific, that require thoughtful consideration when designing a validation framework, including validation metrics and how these metrics impose requirements on the synthetic sky catalogs.

Data to Pictures to Data: Outreach Imaging Software and Metadata

NASA Astrophysics Data System (ADS)

Levay, Z.

2011-07-01

A convergence between astronomy science and digital photography has enabled a steady stream of visually rich imagery from state-of-the-art data. The accessibility of hardware and software has facilitated an explosion of astronomical images for outreach, from space-based observatories, ground-based professional facilities and among the vibrant amateur astrophotography community. Producing imagery from science data involves a combination of custom software to understand FITS data (FITS Liberator), off-the-shelf, industry-standard software to composite multi-wavelength data and edit digital photographs (Adobe Photoshop), and application of photo/image-processing techniques. Some additional effort is needed to close the loop and enable this imagery to be conveniently available for various purposes beyond web and print publication. The metadata paradigms in digital photography are now complying with FITS and science software to carry information such as keyword tags and world coordinates, enabling these images to be usable in more sophisticated, imaginative ways exemplified by Sky in Google Earth and World Wide Telescope.

BAO plate archive digitization

NASA Astrophysics Data System (ADS)

Mickaelian, A. M.; Nikoghosyan, E. H.; Gigoyan, K. S.; Paronyan, G. M.; Abrahamyan, H. V.; Andreasyan, H. R.; Azatyan, N. M.; Kostandyan, G. R.; Khachatryan, K. G.; Vardanyan, A. V.; Gyulzadyan, M. V.; Mikayelyan, G. A.; Farmanyan, S. V.; Knyazyan, A. V.

Astronomical plate archives created on the basis of numerous observations at many observatories are important part of the astronomical heritage. Byurakan Astrophysical Observatory (BAO) plate archive consists of 37,000 photographic plates and films, obtained at 2.6m telescope, 1m and 0.5m Schmidt telescopes and other smaller ones during 1947-1991. In 2015, we have started a project on the whole BAO Plate Archive digitization, creation of electronic database and its scientific usage. A Science Program Board is created to evaluate the observing material, to investigate new possibilities and to propose new projects based on the combined usage of these observations together with other world databases. The Executing Team consists of 11 astronomers and 2 computer scientists and will use 2 EPSON Perfection V750 Pro scanners for the digitization. The project will run during 3 years in 2015-2017 and the final result will be an electronic database and online interactive sky map to be used for further research projects.

Galaxy Evolution Insights from Spectral Modeling of Large Data Sets from the Sloan Digital Sky Survey

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hoversten, Erik A.

This thesis centers on the use of spectral modeling techniques on data from the Sloan Digital Sky Survey (SDSS) to gain new insights into current questions in galaxy evolution. The SDSS provides a large, uniform, high quality data set which can be exploited in a number of ways. One avenue pursued here is to use the large sample size to measure precisely the mean properties of galaxies of increasingly narrow parameter ranges. The other route taken is to look for rare objects which open up for exploration new areas in galaxy parameter space. The crux of this thesis is revisitingmore » the classical Kennicutt method for inferring the stellar initial mass function (IMF) from the integrated light properties of galaxies. A large data set (~ 10 5 galaxies) from the SDSS DR4 is combined with more in-depth modeling and quantitative statistical analysis to search for systematic IMF variations as a function of galaxy luminosity. Galaxy Hα equivalent widths are compared to a broadband color index to constrain the IMF. It is found that for the sample as a whole the best fitting IMF power law slope above 0.5 M ⊙ is Γ = 1.5 ± 0.1 with the error dominated by systematics. Galaxies brighter than around M r,0.1 = -20 (including galaxies like the Milky Way which has M r,0.1 ~ -21) are well fit by a universal Γ ~ 1.4 IMF, similar to the classical Salpeter slope, and smooth, exponential star formation histories (SFH). Fainter galaxies prefer steeper IMFs and the quality of the fits reveal that for these galaxies a universal IMF with smooth SFHs is actually a poor assumption. Related projects are also pursued. A targeted photometric search is conducted for strongly lensed Lyman break galaxies (LBG) similar to MS1512-cB58. The evolution of the photometric selection technique is described as are the results of spectroscopic follow-up of the best targets. The serendipitous discovery of two interesting blue compact dwarf galaxies is reported. These galaxies were identified by their extremely weak (< 150) [N π] Γ6584 to Hα emission line ratios. Abundance analysis from emission line fluxes reveals that these galaxies have gas phase oxygen abundances 12 + log(O/H) ~ 7.7 to 7.9, not remarkably low, and near infrared imaging detects an old stellar population. However, the measured nitrogen to oxygen ratios log(N/O) < 1.7 are anomalously low for blue compact dwarf galaxies. These objects may be useful for understanding the chemical evolution of nitrogen.« less

Search for Variables in the Kepler Field on DASCH Plates

NASA Astrophysics Data System (ADS)

Tang, Sumin; Grindlay, J.; Los, E.; Servillat, M.

2011-01-01

The Digital Access to a Sky Century @ Harvard (DASCH) is a project to digitize the half a million glass photographic plates over the period 1880s-1980s. This 100 year coverage is a unique resource for studying temporal variations in the universe. Here we present our variable search algorithms and variable catalog in the Kepler fields based on 3000 scanned plates. We use the KIC spectral classifications to search for long-term variability of any main sequence stars, particularly M dwarfs. We apply a variability search technique developed for DASCH and set limits on the fraction of main sequence stars, by spectral type, which show detectable (>0.2mag) variability on timescales 10-100y. Such limits are of particular interest for M dwarfs given the recent discoveries of their planet systems.

The global blue-sky albedo change between 2000 - 2015 seen from MODIS

NASA Astrophysics Data System (ADS)

Chrysoulakis, N.; Mitraka, Z.; Gorelick, N.

2016-12-01

The land surface albedo is a critical physical variable, which influences the Earth's climate by affecting the energy budget and distribution in the Earth-atmosphere system. Blue-sky albedo estimates provide a quantitative means for better constraining global and regional scale climate models. The Moderate Resolution Imaging Spectroradiometer (MODIS) albedo product includes parameters for the estimation of both the directional-hemispherical surface reflectance (black-sky albedo) and the bi-hemispherical surface reflectance (white-sky albedo). This dataset was used here for the blue-sky albedo estimation over the globe on an 8-day basis at 0.5 km spatial resolution for the whole time period covered by MODIS acquisitions (i.e. 2000 until today). To estimate the blue-sky albedo, the fraction of the diffused radiation is needed, a function of the Aerosol Optical Thickness (AOT). Required AOT information was acquired from the MODIS AOT product at 1̊ × 1̊ spatial resolution. Since the blue-sky albedo depends on the solar zenith angle (SZA), the 8-day mean blue-sky albedo values were computed as averages of the corresponding values for the representative SZAs covering the 24-hour day. The estimated blue-sky albedo time series was analyzed to capture changes during the 15 period. All computation were performed using the Google Earth Engine (GEE). The GEE provided access to all the MODIS products needed for the analysis without the need of searching or downloading. Moreover, the combination of MODIS products in both temporal and spatial terms was fast and effecting using the GEE API (Application Program Interface). All the products covering the globe and for the time period of 15 years were processed via a single collection. Most importantly, GEE allowed for including the calculation of SZAs covering the 24-hour day which improves the quality of the overall product. The 8-day global products of land surface albedo are available through http://www.rslab.gr/downloads.html

COSMO-SkyMed and GIS applications

NASA Astrophysics Data System (ADS)

Milillo, Pietro; Sole, Aurelia; Serio, Carmine

2013-04-01

Geographic Information Systems (GIS) and Remote Sensing have become key technology tools for the collection, storage and analysis of spatially referenced data. Industries that utilise these spatial technologies include agriculture, forestry, mining, market research as well as the environmental analysis . Synthetic Aperture Radar (SAR) is a coherent active sensor operating in the microwave band which exploits relative motion between antenna and target in order to obtain a finer spatial resolution in the flight direction exploiting the Doppler effect. SAR have wide applications in Remote Sensing such as cartography, surface deformation detection, forest cover mapping, urban planning, disasters monitoring , surveillance etc… The utilization of satellite remote sensing and GIS technology for this applications has proven to be a powerful and effective tool for environmental monitoring. Remote sensing techniques are often less costly and time-consuming for large geographic areas compared to conventional methods, moreover GIS technology provides a flexible environment for, analyzing and displaying digital data from various sources necessary for classification, change detection and database development. The aim of this work si to illustrate the potential of COSMO-SkyMed data and SAR applications in a GIS environment, in particular a demostration of the operational use of COSMO-SkyMed SAR data and GIS in real cases will be provided for what concern DEM validation, river basin estimation, flood mapping and landslide monitoring.

Imaging and mapping the impact of clouds on skyglow with all-sky photometry.

PubMed

Jechow, Andreas; Kolláth, Zoltán; Ribas, Salvador J; Spoelstra, Henk; Hölker, Franz; Kyba, Christopher C M

2017-07-27

Artificial skyglow is constantly growing on a global scale, with potential ecological consequences ranging up to affecting biodiversity. To understand these consequences, worldwide mapping of skyglow for all weather conditions is urgently required. In particular, the amplification of skyglow by clouds needs to be studied, as clouds can extend the reach of skyglow into remote areas not affected by light pollution on clear nights. Here we use commercial digital single lens reflex cameras with fisheye lenses for all-sky photometry. We track the reach of skyglow from a peri-urban into a remote area on a clear and a partly cloudy night by performing transects from the Spanish town of Balaguer towards Montsec Astronomical Park. From one single all-sky image, we extract zenith luminance, horizontal and scalar illuminance. While zenith luminance reaches near-natural levels at 5 km distance from the town on the clear night, similar levels are only reached at 27 km on the partly cloudy night. Our results show the dramatic increase of the reach of skyglow even for moderate cloud coverage at this site. The powerful and easy-to-use method promises to be widely applicable for studies of ecological light pollution on a global scale also by non-specialists in photometry.

The Large Area KX Quasar Survey: Photometric Redshift Selection and the Complete Quasar Catalogue

NASA Astrophysics Data System (ADS)

Maddox, Natasha; Hewett, P. C.; Peroux, C.

2013-01-01

We have completed a large area, ˜600 square degree, spectroscopic survey for luminous quasars flux-limited in the K-band. The survey utilises the UKIRT Infrared Deep Sky Survey (UKIDSS) Large Area Survey (LAS) in regions of sky within the Sloan Digital Sky Survey (SDSS) footprint. We exploit the K-band excess (KX) of all quasars with respect to Galactic stars in combination with a custom-built photometric redshift/classification scheme to identify quasar candidates for spectroscopic follow-up observations. The survey is complete to K≤16.6, and includes >3200 known quasars from the SDSS, with more than 250 additional confirmed quasars from the KX-selection which eluded the SDSS quasar selection algorithm. The selection is >95% complete with respect to known SDSS quasars and >95% efficient, largely independent of redshift and magnitude. The KX-selected quasars will provide new constraints on the fraction of luminous quasars reddened by dust with E(B-V)≤0.5 mag. Several projects utilizing the KX quasars are ongoing, including a spectroscopic campaign searching for dusty quasar intervening absorption systems. The KX survey is a well-defined sample of quasars useful for investigating the properties of luminous quasars with intermediate levels of dust extinction either within their host galaxies or due to intervening absorption systems.

Properties of Spectrally Defined Red QSOs at z = 0.3–1.2

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tsai, A.-L.; Hwang, C.-Y., E-mail: altsai@astro.ncu.edu.tw, E-mail: hwangcy@astro.ncu.edu.tw

We investigated the properties of a sample of red Quasi-stellar Objects (QSOs) using optical, radio, and infrared data. These QSOs were selected from the Sloan Digital Sky Survey Data Release 7 quasar catalog. We only selected sources with sky coverage in the Very Large Array Faint Images of the Radio Sky at Twenty-centimeters survey, and searched for sources with Wide-field Infrared Survey Explorer counterparts. We defined the spectral color of the QSOs based on the flux ratio of the rest-frame 4000 to 3000 Å continuum emission to select red QSOs and typical QSOs. In accordance with this criterion, only QSOsmore » with redshifts between 0.3 and 1.2 could be selected. We found that red QSOs have stronger infrared emission than typical QSOs. We noted that the number ratios of red QSOs to typical QSOs decrease with increasing redshifts, although the number of typical QSOs increase with redshifts. Furthermore, at high redshifts, the luminosity distributions of typical QSOs and red QSOs seem to have similar peaks; however, at low redshifts, the luminosities of red QSOs seem to be lower than those of typical QSOs. These findings suggest that there might be at least two types of red QSOs in our QSO samples.« less

Cosmic Cinematography With the LSSTO

NASA Astrophysics Data System (ADS)

Liu, C. T.; Borne, K.; Stubbs, C.; Tyson, J. A.; LSSTO Collaboration

2001-12-01

The Large-Area Synoptic Survey Telescope Observatory (LSSTO; http://lssto.org) will be an 8.4-meter, 7 square-degree field telescope and camera, and will represent an increase in astronomical survey power more than 20-fold over any observatory now operating or under construction. Each night, LSSTO will image over 1400 square degrees of sky, to a depth of at least 24th magnitude, and make the data publicly available the next day. A co-added deep color image of 14,000 square degrees of the sky to 27th magnitude will also be available. The LSSTO database will be on spinning disks at various sites around the world. At 0.2 arcseconds per pixel, these data will represent unprecedented deep sky images which will follow celestial changes in time. We show some of the plans to broaden the scope of the LSSTO project to include small colleges, amateur astronomers, K-12 and general public astronomy consumers. These include [1] High definition video walls with data feeds of 1000 GB/sec; [2] 3-D virtual reality displays using both personal computers and massive projection systems such as the Hayden Planetarium Digital Dome; and [3] interactive data analysis and viewing in the time dimension, producing a true ``movie of the cosmos."

Wide Field Radio Transient Surveys

NASA Astrophysics Data System (ADS)

Bower, Geoffrey

2011-04-01

The time domain of the radio wavelength sky has been only sparsely explored. Nevertheless, serendipitous discovery and results from limited surveys indicate that there is much to be found on timescales from nanoseconds to years and at wavelengths from meters to millimeters. These observations have revealed unexpected phenomena such as rotating radio transients and coherent pulses from brown dwarfs. Additionally, archival studies have revealed an unknown class of radio transients without radio, optical, or high-energy hosts. The new generation of centimeter-wave radio telescopes such as the Allen Telescope Array (ATA) will exploit wide fields of view and flexible digital signal processing to systematically explore radio transient parameter space, as well as lay the scientific and technical foundation for the Square Kilometer Array. Known unknowns that will be the target of future transient surveys include orphan gamma-ray burst afterglows, radio supernovae, tidally-disrupted stars, flare stars, and magnetars. While probing the variable sky, these surveys will also provide unprecedented information on the static radio sky. I will present results from three large ATA surveys (the Fly's Eye survey, the ATA Twenty CM Survey (ATATS), and the Pi GHz Survey (PiGSS)) and several small ATA transient searches. Finally, I will discuss the landscape and opportunities for future instruments at centimeter wavelengths.

Frankenstein Galaxy

NASA Image and Video Library

2016-07-11

The galaxy UGC 1382 has been revealed to be far larger and stranger than previously thought. Astronomers relied on a combination of ground-based and space telescopes to uncover the true nature of this "Frankenstein galaxy." The composite image shows the same galaxy as viewed with different instruments. The component images are also available. In the image at left, UGC 1382 appears to be a simple elliptical galaxy, based on optical data from the Sloan Digital Sky Survey (SDSS). But spiral arms emerged when astronomers incorporated ultraviolet data from the Galaxy Evolution Explorer (GALEX) and deep optical data from SDSS, as seen in the middle image. Combining that with a view of low-density hydrogen gas (shown in green), detected at radio wavelengths by the Very Large Array, scientists discovered that UGC 1382 is a giant, and one of the largest isolated galaxies known. GALEX in particular was able detect very faint features because it operated from space, which is necessary for UV observations because ultraviolet light is absorbed by the Earth's atmosphere. Astronomers also used Stripe 82 of SDSS, a small region of sky where SDSS imaged the sky 80 times longer than the original standard SDSS survey. This enabled optical detection of much fainter features as well. http://photojournal.jpl.nasa.gov/catalog/PIA20695

Our Sky Now and Then: Searches for Lost Stars and Impossible Effects as Probes of Advanced Extraterrestrial Civilizations

NASA Astrophysics Data System (ADS)

Villarroel, Beatriz; Imaz, Inigo; Bergstedt, Josefine

2016-09-01

Searches for extraterrestrial intelligence using large survey data often look for possible signatures of astroengineering. We propose searching for physically impossible effects caused by highly advanced technology by carrying out a search for disappearing galaxies and Milky Way stars. We select ˜10 million objects from USNO-B1.0 with low proper motions (μ < 20 mas yr-1) imaged on the sky in two epochs. We search for objects not found at the expected positions in the Sloan Digital Sky Survey (SDSS) by visually examining images of ˜290,000 USNO-B1.0 objects with no counterpart in the SDSS. We identify some spurious targets in the USNO-B1.0. We find one candidate of interest for follow-up photometry, although it is very uncertain. If the candidate eventually is found, it defines the probability of observing a disappearing-object event in the last decade to less than one in one million in the given samples. Nevertheless, because the complete USNO-B1.0 data set is 100 times larger than any of our samples, we propose an easily accessible citizen science project in search of USNO-B1.0 objects that have disappeared from the SDSS.

The w-effect in interferometric imaging: from a fast sparse measurement operator to superresolution

NASA Astrophysics Data System (ADS)

Dabbech, A.; Wolz, L.; Pratley, L.; McEwen, J. D.; Wiaux, Y.

2017-11-01

Modern radio telescopes, such as the Square Kilometre Array, will probe the radio sky over large fields of view, which results in large w-modulations of the sky image. This effect complicates the relationship between the measured visibilities and the image under scrutiny. In algorithmic terms, it gives rise to massive memory and computational time requirements. Yet, it can be a blessing in terms of reconstruction quality of the sky image. In recent years, several works have shown that large w-modulations promote the spread spectrum effect. Within the compressive sensing framework, this effect increases the incoherence between the sensing basis and the sparsity basis of the signal to be recovered, leading to better estimation of the sky image. In this article, we revisit the w-projection approach using convex optimization in realistic settings, where the measurement operator couples the w-terms in Fourier and the de-gridding kernels. We provide sparse, thus fast, models of the Fourier part of the measurement operator through adaptive sparsification procedures. Consequently, memory requirements and computational cost are significantly alleviated at the expense of introducing errors on the radio interferometric data model. We present a first investigation of the impact of the sparse variants of the measurement operator on the image reconstruction quality. We finally analyse the interesting superresolution potential associated with the spread spectrum effect of the w-modulation, and showcase it through simulations. Our c++ code is available online on GitHub.

Light Pollution Surveys around the Seoul Capital Area: Results from 2009 and 2014

NASA Astrophysics Data System (ADS)

Yu, Jinhee; An, Sung-Ho; Bae, Hyun-Jin; Roh, Eunji; Chiang, Howoo; Kim, Jinhyub; Kim, Seongjoong; Park, Songyoun

2015-08-01

We conducted a series of light pollution surveys in the periods of 2009/2010 and 2014/2015 at ~130 sites within the Seoul Capital Area of South Korea. We quantitatively measured the night sky brightness in the unit of mag/arcsec2 with the ‘SQM (Sky Quality Meter)-L’ by considering the following conditions: 1) fully dark sky after astronomical twilight, 2) good weather with the cloud amount less than 10%, and 3) ensure no contaminations from nearby street lights to the measured value. We find that the night sky is getting darker from the center of Seoul to the outskirts of Gyeonggi-do by a factor of ~40. In both surveys, for example, the brightest site is Namsan Elementary School (Jung-gu, Seoul: 16.3 and 16.5 mag/arcsec2 in 2009/2010 and 2014/2015, respectively), located nearly at the middle of Seoul. Also, the darkest site is Goseong-ri (Gapyeong-gun, Gyeonggi-do: 20.1 and 20.6 mag/arcsec2 in 2009/2010 and 2014/2015, respectively), situated ~50 km northeast of the brightest site. In addition, the night sky brightness in 2014/2015 is on average darker by ~0.4 mag/arcsec2 compared to the brightness in 2009/2010, which indicates the reduced light pollution in the Seoul Capital Area. In this contribution, we will present the maps of the night sky brightness in the capital region of Korea from both surveys, and discuss the possible reasons for the changes in night sky brightness within 5 years.

CONCAM's Fuzzy-Logic All-Sky Star Recognition Algorithm

NASA Astrophysics Data System (ADS)

Shamir, L.; Nemiroff, R. J.

2004-05-01

One of the purposes of the global Night Sky Live (NSL) network of fisheye CONtinuous CAMeras (CONCAMs) is to monitor and archive the entire bright night sky, track stellar variability, and search for transients. The high quality of raw CONCAM data allows automation of stellar object recognition, although distortions of the fisheye lens and frequent slight shifts in CONCAM orientations can make even this seemingly simple task formidable. To meet this challenge, a fuzzy logic based algorithm has been developed that transforms (x,y) image coordinates in the CCD frame into fuzzy right ascension and declination coordinates for use in matching with star catalogs. Using a training set of reference stars, the algorithm statically builds the fuzzy logic model. At runtime, the algorithm searches for peaks, and then applies the fuzzy logic model to perform the coordinate transformation before choosing the optimal star catalog match. The present fuzzy-logic algorithm works much better than our first generation, straightforward coordinate transformation formula. Following this essential step, algorithms dealing with the higher level data products can then provide a stream of photometry for a few hundred stellar objects visible in the night sky. Accurate photometry further enables the computation of all-sky maps of skyglow and opacity, as well as a search for uncataloged transients. All information is stored in XML-like tagged ASCII files that are instantly copied to the public domain and available at http://NightSkyLive.net. Currently, the NSL software detects stars and creates all-sky image files from eight different locations around the globe every 3 minutes and 56 seconds.

Image Acquisition and Quality in Digital Radiography.

PubMed

Alexander, Shannon

2016-09-01

Medical imaging has undergone dramatic changes and technological breakthroughs since the introduction of digital radiography. This article presents information on the development of digital radiography and types of digital radiography systems. Aspects of image quality and radiation exposure control are highlighted as well. In addition, the article includes related workplace changes and medicolegal considerations in the digital radiography environment. ©2016 American Society of Radiologic Technologists.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cuoco, Alessandro; Regis, Marco; Fornengo, Nicolao

We compare the measured angular cross-correlation between the Fermi-Large Area Telescope γ-ray sky and catalogs of extragalactic objects with the expected signal induced by weakly interacting massive particle (WIMP) dark matter (DM). We include a detailed description of the contribution of astrophysical γ-ray emitters such as blazars, misaligned active galactic nucleus (AGN), and star-forming galaxies, and perform a global fit to the measured cross-correlation. Five catalogs are considered: Sloan Digital Sky Survey (SDSS)-DR6 quasars, Two Micron All Sky Survey galaxies, NRAO VLA Sky Survey radio galaxies, SDSS-DR8 Luminous Red Galaxies, and the SDSS-DR8 main galaxy sample. To model the cross-correlation signal,more » we use the halo occupation distribution formalism to estimate the number of galaxies of a given catalog in DM halos and their spatial correlation properties. We discuss uncertainties in the predicted cross-correlation signal arising from the DM clustering and WIMP microscopic properties, which set the DM γ-ray emission. The use of different catalogs probing objects at different redshifts significantly reduces, though not completely, the degeneracy among the different γ-ray components. We find that the presence of a significant WIMP DM signal is allowed by the data but not significantly preferred by the fit, although this is mainly due to a degeneracy with the misaligned AGN component. With modest substructure boost, the sensitivity of this method excludes thermal annihilation cross sections at 95% level for WIMP masses up to few tens of GeV. Constraining the low-redshift properties of astrophysical populations with future data will further improve the sensitivity to DM.« less

Development and implementation of an automated quantitative film digitizer quality control program

NASA Astrophysics Data System (ADS)

Fetterly, Kenneth A.; Avula, Ramesh T. V.; Hangiandreou, Nicholas J.

1999-05-01

A semi-automated, quantitative film digitizer quality control program that is based on the computer analysis of the image data from a single digitized test film was developed. This program includes measurements of the geometric accuracy, optical density performance, signal to noise ratio, and presampled modulation transfer function. The variability of the measurements was less than plus or minus 5%. Measurements were made on a group of two clinical and two laboratory laser film digitizers during a trial period of approximately four months. Quality control limits were established based on clinical necessity, vendor specifications and digitizer performance. During the trial period, one of the digitizers failed the performance requirements and was corrected by calibration.

Extragalactic counterparts to Einstein slew survey sources

NASA Technical Reports Server (NTRS)

Schachter, Jonathan F.; Elvis, Martin; Plummer, David; Remillard, Ron

1992-01-01

The Einstein slew survey consists of 819 bright X-ray sources, of which 636 (or 78 percent) are identified with counterparts in standard catalogs. The importance of bright X-ray surveys is stressed, and the slew survey is compared to the Rosat all sky survey. Statistical techniques for minimizing confusion in arcminute error circles in digitized data are discussed. The 238 slew survey active galactic nuclei, clusters, and BL Lacertae objects identified to date and their implications for logN-logS and source evolution studies are described.

Cosmic Sparklers

NASA Image and Video Library

2015-07-02

This new composite image of stellar cluster NGC 1333 combines X-rays from NASA's Chandra X-ray Observatory (pink); infrared data from NASA's Spitzer Space Telescope (red); and optical data from the Digitized Sky Survey and the National Optical Astronomical Observatories' Mayall 4-meter telescope on Kitt Peak near Tucson, Arizona. The Chandra data reveal 95 young stars glowing in X-ray light, 41 of which had not been seen previously using Spitzer because they lacked infrared emission from a surrounding disk. http://photojournal.jpl.nasa.gov/catalog/PIA19347

Spectral Classification of PSN J15381795+2544173

NASA Astrophysics Data System (ADS)

Silverman, J. M.; Cohen, D. P.; Filippenko, A. V.

2012-06-01

We report that inspection of a noisy CCD spectrum (range 340-1000 nm), obtained on June 27.3 UT with the Shane 3-m reflector (+ Kast spectrograph) at Lick Observatory, shows that PSN J15381795+2544173 (ATEL 4200) is a Type Ia supernova (SN Ia). After removal of the host-galaxy recession velocity of 26,952 km/s (Sloan Digital Sky Survey Data Release 6), we find the absorption minimum of the Si II 635.5-nm line to be blueshifted by about 11,700 km/s.

Modelling digital thunder

NASA Astrophysics Data System (ADS)

Blanco, Francesco; La Rocca, Paola; Petta, Catia; Riggi, Francesco

2009-01-01

An educational model simulation of the sound produced by lightning in the sky has been employed to demonstrate realistic signatures of thunder and its connection to the particular structure of the lightning channel. Algorithms used in the past have been revisited and implemented, making use of current computer techniques. The basic properties of the mathematical model, together with typical results and suggestions for additional developments are discussed. The paper is intended as a teaching aid for students and teachers in the context of introductory physics courses at university level.

Application of MIMO Techniques in sky-surface wave hybrid networking sea-state radar system

NASA Astrophysics Data System (ADS)

Zhang, L.; Wu, X.; Yue, X.; Liu, J.; Li, C.

2016-12-01

The sky-surface wave hybrid networking sea-state radar system contains of the sky wave transmission stations at different sites and several surface wave radar stations. The subject comes from the national 863 High-tech Project of China. The hybrid sky-surface wave system and the HF surface wave system work simultaneously and the HF surface wave radar (HFSWR) can work in multi-static and surface-wave networking mode. Compared with the single mode radar system, this system has advantages of better detection performance at the far ranges in ocean dynamics parameters inversion. We have applied multiple-input multiple-output(MIMO) techniques in this sea-state radar system. Based on the multiple channel and non-causal transmit beam-forming techniques, the MIMO radar architecture can reduce the size of the receiving antennas and simplify antenna installation. Besides, by efficiently utilizing the system's available degrees of freedom, it can provide a feasible approach for mitigating multipath effect and Doppler-spread clutter in Over-the-horizon Radar. In this radar, slow-time phase-coded MIMO method is used. The transmitting waveforms are phase-coded in slow-time so as to be orthogonal after Doppler processing at the receiver. So the MIMO method can be easily implemented without the need to modify the receiver hardware. After the radar system design, the MIMO experiments of this system have been completed by Wuhan University during 2015 and 2016. The experiment used Wuhan multi-channel ionospheric sounding system(WMISS) as sky-wave transmitting source and three dual-frequency HFSWR developed by the Oceanography Laboratory of Wuhan University. The transmitter system located at Chongyang with five element linear equi-spaced antenna array and Wuhan with one log-periodic antenna. The RF signals are generated by synchronized, but independent digital waveform generators - providing complete flexibility in element phase and amplitude control, and waveform type and parameters. The field experimental results show the presented method is effective. The echoes are obvious and distinguishable both in co-located MIMO mode and widely distributed MIMO mode. Key words: sky-surface wave hybrid networking; sea-state radar; MIMO; phase-coded

It’s about time: How do sky surveys manage uncertainty about scientific needs many years into the future

NASA Astrophysics Data System (ADS)

Darch, Peter T.; Sands, Ashley E.

2016-06-01

Sky surveys, such as the Sloan Digital Sky Survey (SDSS) and the Large Synoptic Survey Telescope (LSST), generate data on an unprecedented scale. While many scientific projects span a few years from conception to completion, sky surveys are typically on the scale of decades. This paper focuses on critical challenges arising from long timescales, and how sky surveys address these challenges.We present findings from a study of LSST, comprising interviews (n=58) and observation. Conceived in the 1990s, the LSST Corporation was formed in 2003, and construction began in 2014. LSST will commence data collection operations in 2022 for ten years.One challenge arising from this long timescale is uncertainty about future needs of the astronomers who will use these data many years hence. Sources of uncertainty include scientific questions to be posed, astronomical phenomena to be studied, and tools and practices these astronomers will have at their disposal. These uncertainties are magnified by the rapid technological and scientific developments anticipated between now and the start of LSST operations.LSST is implementing a range of strategies to address these challenges. Some strategies involve delaying resolution of uncertainty, placing this resolution in the hands of future data users. Other strategies aim to reduce uncertainty by shaping astronomers’ data analysis practices so that these practices will integrate well with LSST once operations begin.One approach that exemplifies both types of strategy is the decision to make LSST data management software open source, even now as it is being developed. This policy will enable future data users to adapt this software to evolving needs. In addition, LSST intends for astronomers to start using this software well in advance of 2022, thereby embedding LSST software and data analysis approaches in the practices of astronomers.These findings strengthen arguments for making the software supporting sky surveys available as open source. Such arguments usually focus on reuse potential of software, and enhancing replicability of analyses. In this case, however, open source software also promises to mitigate the critical challenge of anticipating the needs of future data users.

ISO9000 and the quality management system in the digital hospital.

PubMed

Liu, Yalan; Yao, Bin; Zhang, Zigang

2002-01-01

ISO9000 quality management system (ISO9000QMS) emphasize on the customer-oriented, managers' leadership and all staff's joining, adopt the process method and system management, spread the taking facts as a basis to make decision and improve consistently, and establish win-win relation with the suppliers. So, the digital hospital can adopt the ISO9000QMS. In order to establish the ISO9000QMS, the digital hospital should: (1) Design integrally, including analyzing the operation procedure, clarifying the job duties, setting up the spreading team and setting the quality policy and objectives: (2) Learning the ISO9000 quality standards; (3) Drawing up the documents, including the quality manual, program files and operation guiding files; (4) Training according the documents; (5) Executing the quality standard, including the service quality auditing, quality record auditing and quality system auditing; (6) Improving continually. With the establishment of ISO900QMS, the digital hospital can appraise more accurately, analyze quality matters statistically and avoid the interference of artificial factors.

Stars For Citizens With Urban Star Parks and Lighting Specialists

NASA Astrophysics Data System (ADS)

Grigore, Valentin

2015-08-01

General contextOne hundred years ago, almost nobody imagine a life without stars every night even in the urban areas. Now, to see a starry sky is a special event for urban citizens.It is possible to see the stars even inside cities? Yes, but for that we need star parks and lighting specialists as partners.Educational aspectThe citizens must be able to identify the planets, constellations and other celestial objects in their urban residence. This is part of a basic education. The number of the people living in the urban area who never see the main constellations or important stars increase every year. We must do something for our urban community.What is an urban star park?An urban public park where we can see the main constellations can be considered an urban star park. There can be organized a lot of activities as practical lessons of astronomy, star parties, etc.Classification of the urban star parksA proposal for classification of the urban star parks taking in consideration the quality of the sky and the number of the city inhabitants:Two categories:- city star parks for cities with < 100.000 inhabitants- metropolis star parks for cities with > 100.000 inhabitantsFive levels of quality:- 1* level = can see stars of at least 1 magnitude with the naked eyes- 2* level = at least 2 mag- 3* level = at least 3 mag- 4* level= at least 4 mag- 5* level = at least 5 magThe urban star urban park structure and lighting systemA possible structure of a urban star park and sky-friend lighting including non-electric illumination are descripted.The International Commission on IlluminationA description of this structure which has as members national commissions from all over the world.Dark-sky activists - lighting specialistsNational Commissions on Illumination organize courses of lighting specialist. Dark-sky activists can become lighting specialists. The author shows his experience in this aspect as a recent lighting specialist and his cooperation with the Romanian National Commission on Illumination working for a law of illumination in Romania and to implement the sky protection elements into the lighting specialist accreditation.

Clinical performance of a prototype flat-panel digital detector for general radiography

NASA Astrophysics Data System (ADS)

Huda, Walter; Scalzetti, Ernest M.; Roskopf, Marsha L.; Geiger, Robert

2001-08-01

Digital radiographs obtained using a prototype Digital Radiography System (Stingray) were compared with those obtained using conventional screen-film. Forty adult volunteers each had two identical radiographs taken at the same level of radiation exposure, one using screen-film and the other the digital detector. Each digital image was processed by hand to ensure that the printed quality was optimal. Ten radiologists compared the diagnostic image quality of the digital images with the corresponding film radiographs using a seven point ranking scheme.

The Digital Planetarium: A New Frontier of Public Outreach

NASA Astrophysics Data System (ADS)

Buick, David; Pailevanian, T.; Harootonian, S.; Garibyan, A.; Krestow, J.

2013-01-01

Inspiring youth to pursue the STEM fields is a vital aspect of modern society. Not only does a digital planetarium provide the catalyst to spark the minds of children, but to an assortment of age groups, in a variety of mediums. A digital planetarium is a versatile theatrical environment that can be used for a variety of purposes. The digital planetarium at Glendale Community College is the shining star of the campus. Its ability to satisfy the needs of multiple departments such as, the physical sciences, the biological sciences, the arts, and the foreign languages has become the sharpest tool for public outreach. In this poster we will be discussing the several uses of Glendale Community College’s digital planetarium as well as the programs used to implement them. The central functions of the digital planetarium includes: educational shows, college classes, and entertainment. Educational shows consist of visiting grade school groups, as well as afternoon shows about a specific astronomical topics, which are open to the public. The planetarium is also used to allow Glendale Community College students to see a visual representation of the current curriculum covered in their courses, such as astronomy, organic chemistry, and geology. The true ingenuity and flexibility of the planetarium is the software. Digital Sky allows for the projection of rendered of movies, 3D modeling and student art in the appropriate formats, onto the dome. The digital planetarium is a wonderful tool used to assist, reach out to and display the majesty and complexity of the sciences in an innovative and dynamic method.

The Universe Observing Center a modern center to teach and communicate astronomy

NASA Astrophysics Data System (ADS)

Ribas, Salvador J.

2011-06-01

The Universe Observing Center is one of the parts of the Parc Astronòmic Montsec (PAM). PAM is an initiative of the Catalan government, through the Consorci del Montsec (Montsec Consortium), to take advantage of the capabilities and potential of the Montsec region to develop scientific research, training and outreach activities, particularly in the field of Astronomy. The choice of the Montsec mountains to install the PAM was motivated by the magnificent conditions for observing the sky at night; the sky above Montsec is the best (natural sky free of light pollution) in Catalonia for astronomical observations. The PAM has two main parts: the Observatori Astronòmic del Montsec (OAdM) and the Universe Observing Center (COU). The OAdM is a professional observatory with an 80-cm catadioptric telescope (Joan Oró Telescope). This telescope is a robotic telescope that can be controlled from anywhere in the world via the Internet. The COU is a large multipurpose center which is intended to become an educational benchmark for teaching and communicate astronomy and other sciences in Catalonia. The management of the COU has three main goals: 1) Teach primary and secondary school students in our Educational Training Camp. 2) Teach university students housing the practical astronomy lectures of the universities. 3) Communicate astronomy to the general public. The COU comprises special areas for these purposes: the Telescopes Park with more than 20 telescopes, a coelostat for solar observations and two dome containing full-automated telescopes. The most special equipment is ``The Eye of Montsec'', with its 12m dome containing a multimedia digital planetarium and a platform for direct observation of the sky and the environment. During 2009 we expect around 10000 visitors in Montsec area to enjoy science with Montsec dark skies and an special natural environment.

Data annotation, recording and mapping system for the US open skies aircraft

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brown, B.W.; Goede, W.F.; Farmer, R.G.

1996-11-01

This paper discusses the system developed by Northrop Grumman for the Defense Nuclear Agency (DNA), US Air Force, and the On-Site Inspection Agency (OSIA) to comply with the data annotation and reporting provisions of the Open Skies Treaty. This system, called the Data Annotation, Recording and Mapping System (DARMS), has been installed on the US OC-135 and meets or exceeds all annotation requirements for the Open Skies Treaty. The Open Skies Treaty, which will enter into force in the near future, allows any of the 26 signatory countries to fly fixed wing aircraft with imaging sensors over any of themore » other treaty participants, upon very short notice, and with no restricted flight areas. Sensor types presently allowed by the treaty are: optical framing and panoramic film cameras; video cameras ranging from analog PAL color television cameras to the more sophisticated digital monochrome and color line scanning or framing cameras; infrared line scanners; and synthetic aperture radars. Each sensor type has specific performance parameters which are limited by the treaty, as well as specific annotation requirements which must be achieved upon full entry into force. DARMS supports U.S. compliance with the Opens Skies Treaty by means of three subsystems: the Data Annotation Subsytem (DAS), which annotates sensor media with data obtained from sensors and the aircraft`s avionics system; the Data Recording System (DRS), which records all sensor and flight events on magnetic media for later use in generating Treaty mandated mission reports; and the Dynamic Sensor Mapping Subsystem (DSMS), which provides observers and sensor operators with a real-time moving map displays of the progress of the mission, complete with instantaneous and cumulative sensor coverages. This paper will describe DARMS and its subsystems in greater detail, along with the supporting avionics sub-systems. 7 figs.« less

Globe At Night: A Dark-skies Awareness Campaign During The International Year Of Astronomy

NASA Astrophysics Data System (ADS)

Walker, Constance E.; Isbell, D.; Pompea, S. M.; Smith, D. A.; Baker, T.

2009-01-01

GLOBE at Night is an international citizen-science event encouraging everyone, scientists, non-scientists, students and the general public, to measure local levels of light pollution and contribute the observations online to a world map. This program is a centerpiece of the Dark Skies Awareness Global Cornerstone Project for the International Year of Astronomy (IYA) as well as the US IYA "Dark Skies are a Universal Resource” theme for 2009. Its goal is to raise public awareness of the impact of artificial lighting on local environments by getting people involved. Utilizing the international networks of its hosts, the GLOBE program at the National Optical Astronomy Observatory, the University Corporation for Atmospheric Research and the Environmental Systems Research Institute, along with the Astronomical Society of the Pacific, the Association of Science and Technology Centers, the Astronomical League and the International Dark-Sky Association, GLOBE at Night is able to engage people from around the world. Data collection and online reporting is simple and user-friendly. During a 13-day campaign in each spring, citizen-scientists take data on light pollution levels by comparing observations with stellar maps of limiting magnitudes toward the constellation, Orion. For more precise measurements, citizen-scientists use digital sky brightness meters. During the campaign period over the last 3 years, 20,000 measurements from 100 countries have been logged. The collected data is available online in a variety of formats and for comparison with data from previous years, Earth at Night satellite data and population density data. We will discuss how students and scientists worldwide can explore and analyze these results. We will provide the "know-how” and the means for session participants to become community advocates for GLOBE at Night in their hometowns. We will also discuss lessons learned, best practices and campaign plans during IYA (March 16-28, 2009). For more information, visit http://www.globe.gov/GaN/.

SOUTHERN COSMOLOGY SURVEY. III. QSOs FROM COMBINED GALEX AND OPTICAL PHOTOMETRY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jimenez, Raul; Verde, Licia; Spergel, David N.

2009-04-15

We present catalogs of QSO candidates selected using photometry from Galaxy Evolution Explorer (GALEX) combined with the Sloan Digital Sky Survey (SDSS) in the Stripe 82 region and Blanco Cosmology Survey (BCS) near declination -55 deg. The SDSS region contains {approx_equal}700 objects with magnitude i < 20 and {approx_equal}3600 objects with i < 21.5 in a {approx_equal}60 deg{sup 2} sky region, while the BCS region contains {approx_equal}280 objects with magnitude i < 20 and {approx}2000 objects with i < 21.5 for a 11 deg{sup 2} sky region that is being observed by three current microwave Sunyaev-Zeldovich surveys. Our QSO catalogmore » is the first one in the BCS region. Deep GALEX exposures ({approx}>2000 s in F {sub UV} and N {sub UV}, except in three fields) provide high signal-to-noise photometry in the GALEX bands (F {sub UV}, N {sub UV} < 24.5 mag). From this data, we select QSO candidates using only GALEX and optical r-band photometry, using the method given by Atlee and Gould. In the Stripe 82 field, 60% (30%) of the GALEX-selected QSOs with optical magnitude i < 20 (i < 21.5) also appear in the Richards et al. QSO catalog constructed using five-band optical SDSS photometry. Comparison with the same catalog by Richards et al. shows that the completeness of the sample is approximately 40% (25%). However, for regions of the sky with very low dust extinction, like the BCS 23-hr field and the Stripe 82 between 0{sup 0} and 10{sup 0} in R.A., our completeness is close to 95%, demonstrating that deep GALEX observations are almost as efficient as multiwavelength observations at finding QSOs. GALEX observations thus provide a viable alternate route to QSO catalogs in sky regions where u-band optical photometry is not available. The full catalog is available at http://www.ice.csic.es/personal/jimenez/PHOTOZ.« less

IAU Resolution 2009 B5 - Commission 50 Draft Action Plan - Presentation and Discussion

NASA Astrophysics Data System (ADS)

Green, R. F.

2015-03-01

IAU Resolution 2009 B5 calls on IAU members to protect the public's right to an unpolluted night sky as well as the astronomical quality of the sky around major research observatories. The multi-pronged approach of Commission 50 includes working with the lighting industry for appropriate products from the solid state revolution, arming astronomers with training and materials for presentation, selective endorsement of key protection issues, cooperation with several other IAU commissions for education and outreach, and provision of clear quantitative priorities for outdoor lighting standards.

ESO unveils an amazing, interactive, 360-degree panoramic view of the entire night sky

NASA Astrophysics Data System (ADS)

2009-09-01

The first of three images of ESO's GigaGalaxy Zoom project - a new magnificent 800-million-pixel panorama of the entire sky as seen from ESO's observing sites in Chile - has just been released online. The project allows stargazers to explore and experience the Universe as it is seen with the unaided eye from the darkest and best viewing locations in the world. This 360-degree panoramic image, covering the entire celestial sphere, reveals the cosmic landscape that surrounds our tiny blue planet. This gorgeous starscape serves as the first of three extremely high-resolution images featured in the GigaGalaxy Zoom project, launched by ESO within the framework of the International Year of Astronomy 2009 (IYA2009). GigaGalaxy Zoom features a web tool that allows users to take a breathtaking dive into our Milky Way. With this tool users can learn more about many different and exciting objects in the image, such as multicoloured nebulae and exploding stars, just by clicking on them. In this way, the project seeks to link the sky we can all see with the deep, "hidden" cosmos that astronomers study on a daily basis. The wonderful quality of the images is a testament to the splendour of the night sky at ESO's sites in Chile, which are the most productive astronomical observatories in the world. The plane of our Milky Way Galaxy, which we see edge-on from our perspective on Earth, cuts a luminous swath across the image. The projection used in GigaGalaxy Zoom place the viewer in front of our Galaxy with the Galactic Plane running horizontally through the image - almost as if we were looking at the Milky Way from the outside. From this vantage point, the general components of our spiral galaxy come clearly into view, including its disc, marbled with both dark and glowing nebulae, which harbours bright, young stars, as well as the Galaxy's central bulge and its satellite galaxies. The painstaking production of this image came about as a collaboration between ESO, the renowned French writer and astrophotographer Serge Brunier and his fellow Frenchman Frédéric Tapissier. Brunier spent several weeks during the period between August 2008 and February 2009 capturing the sky, mostly from ESO observatories at La Silla and Paranal in Chile. In order to cover the full Milky Way, Brunier also made a week-long trip to La Palma, one of the Canary Islands, to photograph the northern skies [1]. Once the raw photographs were in hand, image processing by Tapissier and ESO experts helped to convey accurately the night sky as our eyes behold it [2]. The resulting image, now available on GigaGalaxy Zoom, is composed of almost 300 fields each individually captured by Brunier four times, adding up to nearly 1200 photos that encompass the entire night sky. "I wanted to show a sky that everyone can relate to - with its constellations, its thousands of stars, with names familiar since childhood, its myths shared by all civilisations since Homo became Sapiens," says Brunier. "The image was therefore made as man sees it, with a regular digital camera under the dark skies in the Atacama Desert and on La Palma." As photographing extended over several months, objects from the Solar System came and went through the star fields, with bright planets such as Venus and Jupiter. A brilliant, emerald-green comet also flew by, although spotting it among a background of tens of millions of stars will be difficult (but rewarding). Overall, the creators of the GigaGalaxy Zoom project hope that these tremendous efforts in bringing the night sky as observed under the best conditions on the planet to stargazers everywhere will inspire awe for the beautiful, immense Universe that we live in. "The vision of the IYA2009 is to help people rediscover their place in the Universe through the day- and night-time sky, and this is exactly what the GigaGalaxy Zoom project is all about," says project coordinator Henri Boffin. The second dramatic GigaGalaxy Zoom image will be revealed next week, on 21 September 2009. Notes [1] During his quest, Brunier used a Nikon D3 digital camera. The apparent motion of the sky caused by Earth's rotation was corrected for using a small, precise equatorial mount moving in the opposite direction, which made a whole circle in 23 hours 56 minutes around the Earth's axis of rotation. Each photo required a six-minute exposure, for a total exposure time of more than 120 hours. [2] The data processing, using software called Autopano Pro Giga, took great care in respecting the colours and "texture" of the Milky Way. Frédéric Tapissier needed about 340 computing hours on a powerful PC to complete the task. More information As part of the IYA2009, ESO is participating in several remarkable outreach activities, in line with its world-leading rank in the field of astronomy. ESO is hosting the IYA2009 Secretariat for the International Astronomical Union, which coordinates the Year globally. ESO is one of the Organisational Associates of IYA2009, and was also closely involved in the resolution submitted to the United Nations (UN) by Italy, which led to the UN's 62nd General Assembly proclaiming 2009 the International Year of Astronomy. In addition to a wide array of activities planned both at the local and international level, ESO is leading three of the twelve global Cornerstone Projects. ESO, the European Southern Observatory, is the foremost intergovernmental astronomy organisation in Europe and the world's most productive astronomical observatory. It is supported by 14 countries: Austria, Belgium, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Portugal, Spain, Sweden, Switzerland and the United Kingdom. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world's most advanced visible-light astronomical observatory. ESO is the European partner of a revolutionary astronomical telescope ALMA, the largest astronomical project in existence. ESO is currently planning a 42-metre European Extremely Large optical/near-infrared Telescope, the E-ELT, which will become "the world's biggest eye on the sky". Serge Brunier is a French journalist, photographer and writer who specialises in popularising astronomy. He is a regular contributor to Science & Vie magazine, and to the France Info radio station. He has written numerous popular astronomy books, translated into over ten languages, and is a prize-winning photographer, who has captured images of solar eclipses from the most amazing places in the world. A life-long quest for the best skies in the world led him to Chile. This whole sky panorama was presented from 25 August till 13 September 2009 in the exhibition "Un ciel pour la planète" (A sky for the planet) in the Atrium of the Monte-Carlo Casino, Monaco. With a giant print of 12 times 6 metres, the exhibition was under the Patronage of The Prince Albert II of Monaco, and showed with images and videos the making of this unique ESO project.

The impact of European measures to reduce air pollutants on air quality, human health and climate

NASA Astrophysics Data System (ADS)

Turnock, S.; Butt, E. W.; Richardson, T.; Mann, G.; Forster, P.; Haywood, J. M.; Crippa, M.; Janssens-Maenhout, G. G. A.; Johnson, C.; Bellouin, N.; Spracklen, D. V.; Carslaw, K. S.; Reddington, C.

2015-12-01

European air quality legislation has reduced emissions of air pollutants across Europe since the 1970s, resulting in improved air quality and benefits to human health but also an unintended impact on regional climate. Here we used a coupled chemistry-climate model and a new policy relevant emission scenario to determine the impact of air pollutant emission reductions over Europe. The emission scenario shows that a combination of technological improvements and end-of-pipe abatement measures in the energy, industrial and road transport sectors reduced European emissions of sulphur dioxide, black carbon and organic carbon by 53%, 59% and 32% respectively. We estimate that these emission reductions decreased European annual mean concentrations of fine particulate matter (PM2.5) by 35%, sulphate by 44%, black carbon (BC) by 56% and particulate organic matter (POM) by 23%. The reduction in PM2.5 concentrations is calculated to have prevented 107,000 (40,000-172,000, 5-95% confidence intervals) premature deaths annually from cardiopulmonary disease and lung cancer across the EU member states. The decrease in aerosol concentrations caused a positive all-sky aerosol radiative forcing at the top of atmosphere over Europe of 2.3±0.06 W m-2 and a positive clear-sky forcing of 1.7±0.05 W m-2. Additionally, the amount of solar radiation incident at the surface over Europe increased by 3.3±0.07 W m-2 under all-sky and by 2.7±0.05 W m-2 under clear-sky conditions. Reductions in BC concentrations caused a 1 Wm-2 reduction in atmospheric absorption. We use an energy budget approximation to show that the aerosol induced radiative changes caused both temperature and precipitation to increase globally and over Europe. Our results show that the implementation of European legislation to reduce the emission of air pollutants has improved air quality and human health over Europe, as well as altered the regional radiative balance and climate.

A Catalog of Broad Absorption Line Quasars from the Sloan Digital Sky Survey Third Data Release

NASA Astrophysics Data System (ADS)

Trump, Jonathan R.; Hall, Patrick B.; Reichard, Timothy A.; Richards, Gordon T.; Schneider, Donald P.; Vanden Berk, Daniel E.; Knapp, Gillian R.; Anderson, Scott F.; Fan, Xiaohui; Brinkman, J.; Kleinman, S. J.; Nitta, Atsuko

2006-07-01

We present a total of 4784 unique broad absorption line quasars from the Sloan Digital Sky Survey Third Data Release. An automated algorithm was used to match a continuum to each quasar and to identify regions of flux at least 10% below the continuum over a velocity range of at least 1000 km s-1 in the C IV and Mg II absorption regions. The model continuum was selected as the best-fit match from a set of template quasar spectra binned in luminosity, emission line width, and redshift, with the power-law spectral index and amount of dust reddening as additional free parameters. We characterize our sample through the traditional ``balnicity'' index and a revised absorption index, as well as through parameters such as the width, outflow velocity, fractional depth, and number of troughs. From a sample of 16,883 quasars at 1.7<=z<=4.38, we identify 4386 (26.0%) quasars with broad C IV absorption, of which 1756 (10.4%) satisfy traditional selection criteria. From a sample of 34,973 quasars at 0.5<=z<=2.15, we identify 457 (1.31%) quasars with broad Mg II absorption, 191 (0.55%) of which satisfy traditional selection criteria. We also provide a supplementary list of 39 visually identified z>4.38 quasars with broad C IV absorption. We find that broad absorption line quasars may have broader emission lines on average than other quasars.

Sloan Digital Sky Survey IV: Mapping the Milky Way, nearby galaxies, and the distant universe

DOE Office of Scientific and Technical Information (OSTI.GOV)

Blanton, Michael R.; Bershady, Matthew A.; Abolfathi, Bela

Here, we describe the Sloan Digital Sky Survey IV (SDSS-IV), a project encompassing three major spectroscopic programs. The Apache Point Observatory Galactic Evolution Experiment 2 (APOGEE-2) is observing hundreds of thousands of Milky Way stars at high resolution and high signal-to-noise ratios in the near-infrared. The Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey is obtaining spatially resolved spectroscopy for thousands of nearby galaxies (medianmore » $$z\\sim 0.03$$). The extended Baryon Oscillation Spectroscopic Survey (eBOSS) is mapping the galaxy, quasar, and neutral gas distributions between $$z\\sim 0.6$$ and 3.5 to constrain cosmology using baryon acoustic oscillations, redshift space distortions, and the shape of the power spectrum. Within eBOSS, we are conducting two major subprograms: the SPectroscopic IDentification of eROSITA Sources (SPIDERS), investigating X-ray AGNs and galaxies in X-ray clusters, and the Time Domain Spectroscopic Survey (TDSS), obtaining spectra of variable sources. All programs use the 2.5 m Sloan Foundation Telescope at the Apache Point Observatory; observations there began in Summer 2014. APOGEE-2 also operates a second near-infrared spectrograph at the 2.5 m du Pont Telescope at Las Campanas Observatory, with observations beginning in early 2017. Observations at both facilities are scheduled to continue through 2020. In keeping with previous SDSS policy, SDSS-IV provides regularly scheduled public data releases; the first one, Data Release 13, was made available in 2016 July.« less

Sloan Digital Sky Survey IV: Mapping the Milky Way, nearby galaxies, and the distant universe

DOE PAGES

Blanton, Michael R.; Bershady, Matthew A.; Abolfathi, Bela; ...

2017-06-29

Here, we describe the Sloan Digital Sky Survey IV (SDSS-IV), a project encompassing three major spectroscopic programs. The Apache Point Observatory Galactic Evolution Experiment 2 (APOGEE-2) is observing hundreds of thousands of Milky Way stars at high resolution and high signal-to-noise ratios in the near-infrared. The Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey is obtaining spatially resolved spectroscopy for thousands of nearby galaxies (medianmore » $$z\\sim 0.03$$). The extended Baryon Oscillation Spectroscopic Survey (eBOSS) is mapping the galaxy, quasar, and neutral gas distributions between $$z\\sim 0.6$$ and 3.5 to constrain cosmology using baryon acoustic oscillations, redshift space distortions, and the shape of the power spectrum. Within eBOSS, we are conducting two major subprograms: the SPectroscopic IDentification of eROSITA Sources (SPIDERS), investigating X-ray AGNs and galaxies in X-ray clusters, and the Time Domain Spectroscopic Survey (TDSS), obtaining spectra of variable sources. All programs use the 2.5 m Sloan Foundation Telescope at the Apache Point Observatory; observations there began in Summer 2014. APOGEE-2 also operates a second near-infrared spectrograph at the 2.5 m du Pont Telescope at Las Campanas Observatory, with observations beginning in early 2017. Observations at both facilities are scheduled to continue through 2020. In keeping with previous SDSS policy, SDSS-IV provides regularly scheduled public data releases; the first one, Data Release 13, was made available in 2016 July.« less

A DATA-DRIVEN MODEL FOR SPECTRA: FINDING DOUBLE REDSHIFTS IN THE SLOAN DIGITAL SKY SURVEY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tsalmantza, P.; Hogg, David W., E-mail: vivitsal@mpia.de

2012-07-10

We present a data-driven method-heteroscedastic matrix factorization, a kind of probabilistic factor analysis-for modeling or performing dimensionality reduction on observed spectra or other high-dimensional data with known but non-uniform observational uncertainties. The method uses an iterative inverse-variance-weighted least-squares minimization procedure to generate a best set of basis functions. The method is similar to principal components analysis (PCA), but with the substantial advantage that it uses measurement uncertainties in a responsible way and accounts naturally for poorly measured and missing data; it models the variance in the noise-deconvolved data space. A regularization can be applied, in the form of a smoothnessmore » prior (inspired by Gaussian processes) or a non-negative constraint, without making the method prohibitively slow. Because the method optimizes a justified scalar (related to the likelihood), the basis provides a better fit to the data in a probabilistic sense than any PCA basis. We test the method on Sloan Digital Sky Survey (SDSS) spectra, concentrating on spectra known to contain two redshift components: these are spectra of gravitational lens candidates and massive black hole binaries. We apply a hypothesis test to compare one-redshift and two-redshift models for these spectra, utilizing the data-driven model trained on a random subset of all SDSS spectra. This test confirms 129 of the 131 lens candidates in our sample and all of the known binary candidates, and turns up very few false positives.« less

The Ninth Data Release of the Sloan Digital Sky Survey: First Spectroscopic Data from the SDSS-III Baryon Oscillation Spectroscopic Survey

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ahn, Christopher P.; Alexandroff, Rachael; Allende Prieto, Carlos

2012-11-19

The Sloan Digital Sky Survey III (SDSS-III) presents the first spectroscopic data from the Baryon Oscillation Spectroscopic Survey (BOSS). This ninth data release (DR9) of the SDSS project includes 535,995 new galaxy spectra (median z=0.52), 102,100 new quasar spectra (median z=2.32), and 90,897 new stellar spectra, along with the data presented in previous data releases. These spectra were obtained with the new BOSS spectrograph and were taken between 2009 December and 2011 July. In addition, the stellar parameters pipeline, which determines radial velocities, surface temperatures, surface gravities, and metallicities of stars, has been updated and refined with improvements in temperaturemore » estimates for stars with T_eff<5000 K and in metallicity estimates for stars with [Fe/H]>-0.5. DR9 includes new stellar parameters for all stars presented in DR8, including stars from SDSS-I and II, as well as those observed as part of the SDSS-III Sloan Extension for Galactic Understanding and Exploration-2 (SEGUE-2). The astrometry error introduced in the DR8 imaging catalogs has been corrected in the DR9 data products. The next data release for SDSS-III will be in Summer 2013, which will present the first data from the Apache Point Observatory Galactic Evolution Experiment (APOGEE) along with another year of data from BOSS, followed by the final SDSS-III data release in December 2014.« less

The SDSS-IV in 2015: Report of the Committee on the Participation of Women in the Sloan Digital Sky Survey

NASA Astrophysics Data System (ADS)

Diamond-Stanic, Aleksandar M.; Lucatello, Sara; Aragon-Salamanca, Alfonso; Cherinka, Brian; Cunha, Katia M. L.; Gillespie, Bruce Andrew; Hagen, Alex; Jones, Amy; Kinemuchi, Karen; Lundgren, Britt; Myers, Adam D.; Roman, Alexandre; Zasowski, Gail; SDSS-IV Collaboration

2016-01-01

Given that many astronomers now participate in large international scientific collaborations, it is important to examine whether these structures foster a healthy scientific climate that is inclusive and diverse. The Committee on the Participation of Women in the Sloan Digital Sky Survey (CPWS) was formed to evaluate the climate and demographics within the SDSS collaboration and to make recommendations for how best to establish the scientific and technical leadership team for SDSS-IV. Building on the work described in Lundgren et al. (2015), the CPWS conducted a demographic survey in Spring 2015 that included questions about career and leadership status, racial / ethnic identity, gender identity, identification with the LGBT community, disability, partnership status, and level of parental education. For example, 71% of survey respondents identify as male and 81% do not identify as a racial or ethnic minority at their current institution. This reflects the under-representation of women and men from minority groups (e.g., people of color in the United States) and women from majority groups (e.g., white women in the United States) in the field of astronomy. We have focused our analysis on the representation of scientists from these groups among the SDSS-IV leadership and the full collaboration. Our goal is to use these quantitative data to track the demographics of SDSS-IV membership and leadership over time as we work to assess and improve the climate of SDSS-IV.

Gamma-Ray-emitting Narrow-line Seyfert 1 Galaxies in the Sloan Digital Sky Survey

NASA Astrophysics Data System (ADS)

Paliya, Vaidehi S.; Ajello, M.; Rakshit, S.; Mandal, Amit Kumar; Stalin, C. S.; Kaur, A.; Hartmann, D.

2018-01-01

The detection of significant γ-ray emission from radio-loud narrow-line Seyfert 1 (NLSy1s) galaxies enables us to study jets in environments different than those in blazars. However, due to the small number of known γ-ray-emitting NLSy1 (γ-NLSy1) galaxies, a comprehensive study could not be performed. Here, we report the first detection of significant γ-ray emission from four active galactic nuclei (AGNs), recently classified as NLSy1 from their Sloan Digital Sky Survey (SDSS) optical spectrum. Three flat-spectrum radio quasars (FSRQs) present in the third Large Area Telescope AGN catalog (3LAC) are also found as γ-NLSy1 galaxies. Comparing the γ-ray properties of these objects with 3LAC blazars reveals their spectral shapes to be similar to FSRQs, however, with low γ-ray luminosity (≲1046–47 erg s‑1). In the Wide-field Infrared Survey Explorer color–color diagram, these objects occupy a region mainly populated by FSRQs. Using the H β emission line parameters, we find that on average γ-NLSy1 have smaller black hole masses than FSRQs at similar redshifts. In the low-resolution SDSS image of one of the γ-NLSy1 source, we find the evidence of an extended structure. We conclude by noting that overall many observational properties of γ-NLSy1 sources are similar to FSRQs, and therefore these objects could be their low black hole mass counterparts, as predicted in the literature.

Genus Topology of Structure in the Sloan Digital Sky Survey: Model Testing

NASA Astrophysics Data System (ADS)

Gott, J. Richard, III; Hambrick, D. Clay; Vogeley, Michael S.; Kim, Juhan; Park, Changbom; Choi, Yun-Young; Cen, Renyue; Ostriker, Jeremiah P.; Nagamine, Kentaro

2008-03-01

We measure the three-dimensional topology of large-scale structure in the Sloan Digital Sky Survey (SDSS). This allows the genus statistic to be measured with unprecedented statistical accuracy. The sample size is now sufficiently large to allow the topology to be an important tool for testing galaxy formation models. For comparison, we make mock SDSS samples using several state-of-the-art N-body simulations: the Millennium run of Springel et al. (10 billion particles), the Kim & Park CDM models (1.1 billion particles), and the Cen & Ostriker hydrodynamic code models (8.6 billion cell hydro mesh). Each of these simulations uses a different method for modeling galaxy formation. The SDSS data show a genus curve that is broadly characteristic of that produced by Gaussian random-phase initial conditions. Thus, the data strongly support the standard model of inflation where Gaussian random-phase initial conditions are produced by random quantum fluctuations in the early universe. But on top of this general shape there are measurable differences produced by nonlinear gravitational effects and biasing connected with galaxy formation. The N-body simulations have been tuned to reproduce the power spectrum and multiplicity function but not topology, so topology is an acid test for these models. The data show a "meatball" shift (only partly due to the Sloan Great Wall of galaxies) that differs at the 2.5 σ level from the results of the Millenium run and the Kim & Park dark halo models, even including the effects of cosmic variance.

Luminosity and redshift dependence of the covering factor of active galactic nuclei viewed with WISE and Sloan digital sky survey

DOE Office of Scientific and Technical Information (OSTI.GOV)

Toba, Y.; Matsuhara, H.; Oyabu, S.

2014-06-10

In this work, we investigate the dependence of the covering factor (CF) of active galactic nuclei (AGNs) on the mid-infrared (MIR) luminosity and the redshift. We constructed 12 and 22 μm luminosity functions (LFs) at 0.006 ≤z ≤ 0.3 using Wide-field Infrared Survey Explorer (WISE) data. Combining the WISE catalog with Sloan Digital Sky Survey (SDSS) spectroscopic data, we selected 223,982 galaxies at 12 μm and 25,721 galaxies at 22 μm for spectroscopic classification. We then identified 16,355 AGNs at 12 μm and 4683 AGNs at 22 μm by their optical emission lines and cataloged classifications in the SDSS. Followingmore » that, we estimated the CF as the fraction of Type 2 AGN in all AGNs whose MIR emissions are dominated by the active nucleus (not their host galaxies) based on their MIR colors. We found that the CF decreased with increasing MIR luminosity, regardless of the choice of Type 2 AGN classification criteria, and the CF did not change significantly with redshift for z ≤ 0.2. Furthermore, we carried out various tests to determine the influence of selection bias and confirmed that similar dependences exist, even when taking these uncertainties into account. The luminosity dependence of the CF can be explained by the receding torus model, but the 'modified' receding torus model gives a slightly better fit, as suggested by Simpson.« less

A high-resolution atlas of composite Sloan Digital Sky Survey galaxy spectra

NASA Astrophysics Data System (ADS)

Dobos, László; Csabai, István.; Yip, Ching-Wa; Budavári, Tamás.; Wild, Vivienne; Szalay, Alexander S.

2012-02-01

In this work we present an atlas of composite spectra of galaxies based on the data of the Sloan Digital Sky Survey Data Release 7 (SDSS DR7). Galaxies are classified by colour, nuclear activity and star formation activity to calculate average spectra of high signal-to-noise ratio (S/N) and resolution (? at Δλ= 1 Å), using an algorithm that is robust against outliers. Besides composite spectra, we also compute the first five principal components of the distributions in each galaxy class to characterize the nature of variations of individual spectra around the averages. The continua of the composite spectra are fitted with BC03 stellar population synthesis models to extend the wavelength coverage beyond the coverage of the SDSS spectrographs. Common derived parameters of the composites are also calculated: integrated colours in the most popular filter systems, line-strength measurements and continuum absorption indices (including Lick indices). These derived parameters are compared with the distributions of parameters of individual galaxies, and it is shown on many examples that the composites of the atlas cover much of the parameter space spanned by SDSS galaxies. By co-adding thousands of spectra, a total integration time of several months can be reached, which results in extremely low noise composites. The variations in redshift not only allow for extending the spectral coverage bluewards to the original wavelength limit of the SDSS spectrographs, but also make higher spectral resolution achievable. The composite spectrum atlas is available online at .

Sloan Digital Sky Survey IV: Mapping the Milky Way, Nearby Galaxies, and the Distant Universe

NASA Astrophysics Data System (ADS)

Blanton, Michael R.; Bershady, Matthew A.; Abolfathi, Bela; Albareti, Franco D.; Allende Prieto, Carlos; Almeida, Andres; Alonso-García, Javier; Anders, Friedrich; Anderson, Scott F.; Andrews, Brett; Aquino-Ortíz, Erik; Aragón-Salamanca, Alfonso; Argudo-Fernández, Maria; Armengaud, Eric; Aubourg, Eric; Avila-Reese, Vladimir; Badenes, Carles; Bailey, Stephen; Barger, Kathleen A.; Barrera-Ballesteros, Jorge; Bartosz, Curtis; Bates, Dominic; Baumgarten, Falk; Bautista, Julian; Beaton, Rachael; Beers, Timothy C.; Belfiore, Francesco; Bender, Chad F.; Berlind, Andreas A.; Bernardi, Mariangela; Beutler, Florian; Bird, Jonathan C.; Bizyaev, Dmitry; Blanc, Guillermo A.; Blomqvist, Michael; Bolton, Adam S.; Boquien, Médéric; Borissova, Jura; van den Bosch, Remco; Bovy, Jo; Brandt, William N.; Brinkmann, Jonathan; Brownstein, Joel R.; Bundy, Kevin; Burgasser, Adam J.; Burtin, Etienne; Busca, Nicolás G.; Cappellari, Michele; Delgado Carigi, Maria Leticia; Carlberg, Joleen K.; Carnero Rosell, Aurelio; Carrera, Ricardo; Chanover, Nancy J.; Cherinka, Brian; Cheung, Edmond; Gómez Maqueo Chew, Yilen; Chiappini, Cristina; Doohyun Choi, Peter; Chojnowski, Drew; Chuang, Chia-Hsun; Chung, Haeun; Cirolini, Rafael Fernando; Clerc, Nicolas; Cohen, Roger E.; Comparat, Johan; da Costa, Luiz; Cousinou, Marie-Claude; Covey, Kevin; Crane, Jeffrey D.; Croft, Rupert A. C.; Cruz-Gonzalez, Irene; Garrido Cuadra, Daniel; Cunha, Katia; Damke, Guillermo J.; Darling, Jeremy; Davies, Roger; Dawson, Kyle; de la Macorra, Axel; Dell'Agli, Flavia; De Lee, Nathan; Delubac, Timothée; Di Mille, Francesco; Diamond-Stanic, Aleks; Cano-Díaz, Mariana; Donor, John; Downes, Juan José; Drory, Niv; du Mas des Bourboux, Hélion; Duckworth, Christopher J.; Dwelly, Tom; Dyer, Jamie; Ebelke, Garrett; Eigenbrot, Arthur D.; Eisenstein, Daniel J.; Emsellem, Eric; Eracleous, Mike; Escoffier, Stephanie; Evans, Michael L.; Fan, Xiaohui; Fernández-Alvar, Emma; Fernandez-Trincado, J. G.; Feuillet, Diane K.; Finoguenov, Alexis; Fleming, Scott W.; Font-Ribera, Andreu; Fredrickson, Alexander; Freischlad, Gordon; Frinchaboy, Peter M.; Fuentes, Carla E.; Galbany, Lluís; Garcia-Dias, R.; García-Hernández, D. A.; Gaulme, Patrick; Geisler, Doug; Gelfand, Joseph D.; Gil-Marín, Héctor; Gillespie, Bruce A.; Goddard, Daniel; Gonzalez-Perez, Violeta; Grabowski, Kathleen; Green, Paul J.; Grier, Catherine J.; Gunn, James E.; Guo, Hong; Guy, Julien; Hagen, Alex; Hahn, ChangHoon; Hall, Matthew; Harding, Paul; Hasselquist, Sten; Hawley, Suzanne L.; Hearty, Fred; Gonzalez Hernández, Jonay I.; Ho, Shirley; Hogg, David W.; Holley-Bockelmann, Kelly; Holtzman, Jon A.; Holzer, Parker H.; Huehnerhoff, Joseph; Hutchinson, Timothy A.; Hwang, Ho Seong; Ibarra-Medel, Héctor J.; da Silva Ilha, Gabriele; Ivans, Inese I.; Ivory, KeShawn; Jackson, Kelly; Jensen, Trey W.; Johnson, Jennifer A.; Jones, Amy; Jönsson, Henrik; Jullo, Eric; Kamble, Vikrant; Kinemuchi, Karen; Kirkby, David; Kitaura, Francisco-Shu; Klaene, Mark; Knapp, Gillian R.; Kneib, Jean-Paul; Kollmeier, Juna A.; Lacerna, Ivan; Lane, Richard R.; Lang, Dustin; Law, David R.; Lazarz, Daniel; Lee, Youngbae; Le Goff, Jean-Marc; Liang, Fu-Heng; Li, Cheng; Li, Hongyu; Lian, Jianhui; Lima, Marcos; Lin, Lihwai; Lin, Yen-Ting; Bertran de Lis, Sara; Liu, Chao; de Icaza Lizaola, Miguel Angel C.; Long, Dan; Lucatello, Sara; Lundgren, Britt; MacDonald, Nicholas K.; Deconto Machado, Alice; MacLeod, Chelsea L.; Mahadevan, Suvrath; Geimba Maia, Marcio Antonio; Maiolino, Roberto; Majewski, Steven R.; Malanushenko, Elena; Malanushenko, Viktor; Manchado, Arturo; Mao, Shude; Maraston, Claudia; Marques-Chaves, Rui; Masseron, Thomas; Masters, Karen L.; McBride, Cameron K.; McDermid, Richard M.; McGrath, Brianne; McGreer, Ian D.; Medina Peña, Nicolás; Melendez, Matthew; Merloni, Andrea; Merrifield, Michael R.; Meszaros, Szabolcs; Meza, Andres; Minchev, Ivan; Minniti, Dante; Miyaji, Takamitsu; More, Surhud; Mulchaey, John; Müller-Sánchez, Francisco; Muna, Demitri; Munoz, Ricardo R.; Myers, Adam D.; Nair, Preethi; Nandra, Kirpal; Correa do Nascimento, Janaina; Negrete, Alenka; Ness, Melissa; Newman, Jeffrey A.; Nichol, Robert C.; Nidever, David L.; Nitschelm, Christian; Ntelis, Pierros; O'Connell, Julia E.; Oelkers, Ryan J.; Oravetz, Audrey; Oravetz, Daniel; Pace, Zach; Padilla, Nelson; Palanque-Delabrouille, Nathalie; Alonso Palicio, Pedro; Pan, Kaike; Parejko, John K.; Parikh, Taniya; Pâris, Isabelle; Park, Changbom; Patten, Alim Y.; Peirani, Sebastien; Pellejero-Ibanez, Marcos; Penny, Samantha; Percival, Will J.; Perez-Fournon, Ismael; Petitjean, Patrick; Pieri, Matthew M.; Pinsonneault, Marc; Pisani, Alice; Poleski, Radosław; Prada, Francisco; Prakash, Abhishek; Queiroz, Anna Bárbara de Andrade; Raddick, M. Jordan; Raichoor, Anand; Barboza Rembold, Sandro; Richstein, Hannah; Riffel, Rogemar A.; Riffel, Rogério; Rix, Hans-Walter; Robin, Annie C.; Rockosi, Constance M.; Rodríguez-Torres, Sergio; Roman-Lopes, A.; Román-Zúñiga, Carlos; Rosado, Margarita; Ross, Ashley J.; Rossi, Graziano; Ruan, John; Ruggeri, Rossana; Rykoff, Eli S.; Salazar-Albornoz, Salvador; Salvato, Mara; Sánchez, Ariel G.; Aguado, D. S.; Sánchez-Gallego, José R.; Santana, Felipe A.; Santiago, Basílio Xavier; Sayres, Conor; Schiavon, Ricardo P.; da Silva Schimoia, Jaderson; Schlafly, Edward F.; Schlegel, David J.; Schneider, Donald P.; Schultheis, Mathias; Schuster, William J.; Schwope, Axel; Seo, Hee-Jong; Shao, Zhengyi; Shen, Shiyin; Shetrone, Matthew; Shull, Michael; Simon, Joshua D.; Skinner, Danielle; Skrutskie, M. F.; Slosar, Anže; Smith, Verne V.; Sobeck, Jennifer S.; Sobreira, Flavia; Somers, Garrett; Souto, Diogo; Stark, David V.; Stassun, Keivan; Stauffer, Fritz; Steinmetz, Matthias; Storchi-Bergmann, Thaisa; Streblyanska, Alina; Stringfellow, Guy S.; Suárez, Genaro; Sun, Jing; Suzuki, Nao; Szigeti, Laszlo; Taghizadeh-Popp, Manuchehr; Tang, Baitian; Tao, Charling; Tayar, Jamie; Tembe, Mita; Teske, Johanna; Thakar, Aniruddha R.; Thomas, Daniel; Thompson, Benjamin A.; Tinker, Jeremy L.; Tissera, Patricia; Tojeiro, Rita; Hernandez Toledo, Hector; de la Torre, Sylvain; Tremonti, Christy; Troup, Nicholas W.; Valenzuela, Octavio; Martinez Valpuesta, Inma; Vargas-González, Jaime; Vargas-Magaña, Mariana; Vazquez, Jose Alberto; Villanova, Sandro; Vivek, M.; Vogt, Nicole; Wake, David; Walterbos, Rene; Wang, Yuting; Weaver, Benjamin Alan; Weijmans, Anne-Marie; Weinberg, David H.; Westfall, Kyle B.; Whelan, David G.; Wild, Vivienne; Wilson, John; Wood-Vasey, W. M.; Wylezalek, Dominika; Xiao, Ting; Yan, Renbin; Yang, Meng; Ybarra, Jason E.; Yèche, Christophe; Zakamska, Nadia; Zamora, Olga; Zarrouk, Pauline; Zasowski, Gail; Zhang, Kai; Zhao, Gong-Bo; Zheng, Zheng; Zheng, Zheng; Zhou, Xu; Zhou, Zhi-Min; Zhu, Guangtun B.; Zoccali, Manuela; Zou, Hu

2017-07-01

We describe the Sloan Digital Sky Survey IV (SDSS-IV), a project encompassing three major spectroscopic programs. The Apache Point Observatory Galactic Evolution Experiment 2 (APOGEE-2) is observing hundreds of thousands of Milky Way stars at high resolution and high signal-to-noise ratios in the near-infrared. The Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey is obtaining spatially resolved spectroscopy for thousands of nearby galaxies (median z˜ 0.03). The extended Baryon Oscillation Spectroscopic Survey (eBOSS) is mapping the galaxy, quasar, and neutral gas distributions between z˜ 0.6 and 3.5 to constrain cosmology using baryon acoustic oscillations, redshift space distortions, and the shape of the power spectrum. Within eBOSS, we are conducting two major subprograms: the SPectroscopic IDentification of eROSITA Sources (SPIDERS), investigating X-ray AGNs and galaxies in X-ray clusters, and the Time Domain Spectroscopic Survey (TDSS), obtaining spectra of variable sources. All programs use the 2.5 m Sloan Foundation Telescope at the Apache Point Observatory; observations there began in Summer 2014. APOGEE-2 also operates a second near-infrared spectrograph at the 2.5 m du Pont Telescope at Las Campanas Observatory, with observations beginning in early 2017. Observations at both facilities are scheduled to continue through 2020. In keeping with previous SDSS policy, SDSS-IV provides regularly scheduled public data releases; the first one, Data Release 13, was made available in 2016 July.

On the accurate estimation of gap fraction during daytime with digital cover photography

NASA Astrophysics Data System (ADS)

Hwang, Y. R.; Ryu, Y.; Kimm, H.; Macfarlane, C.; Lang, M.; Sonnentag, O.

2015-12-01

Digital cover photography (DCP) has emerged as an indirect method to obtain gap fraction accurately. Thus far, however, the intervention of subjectivity, such as determining the camera relative exposure value (REV) and threshold in the histogram, hindered computing accurate gap fraction. Here we propose a novel method that enables us to measure gap fraction accurately during daytime under various sky conditions by DCP. The novel method computes gap fraction using a single DCP unsaturated raw image which is corrected for scattering effects by canopies and a reconstructed sky image from the raw format image. To test the sensitivity of the novel method derived gap fraction to diverse REVs, solar zenith angles and canopy structures, we took photos in one hour interval between sunrise to midday under dense and sparse canopies with REV 0 to -5. The novel method showed little variation of gap fraction across different REVs in both dense and spares canopies across diverse range of solar zenith angles. The perforated panel experiment, which was used to test the accuracy of the estimated gap fraction, confirmed that the novel method resulted in the accurate and consistent gap fractions across different hole sizes, gap fractions and solar zenith angles. These findings highlight that the novel method opens new opportunities to estimate gap fraction accurately during daytime from sparse to dense canopies, which will be useful in monitoring LAI precisely and validating satellite remote sensing LAI products efficiently.

Photometric and Spectroscopic Footprint Corrections in the Sloan Digital Sky Survey’s 6th Data Release

NASA Astrophysics Data System (ADS)

Specian, Mike A.; Szalay, Alex S.

2016-04-01

We identify and correct numerous errors within the photometric and spectroscopic footprints (SFs) of the Sloan Digital Sky Survey’s (SDSS) 6th data release (DR6). Within the SDSS’s boundaries hundreds of millions of objects have been detected. Yet we present evidence that the boundaries themselves contain a significant number of mistakes that are being revealed for the first time within this paper. Left unaddressed, these can introduce systematic biases into galaxy clustering statistics. Using the DR6 Main Galaxy Sample (MGS) targets as tracers, we reveal inconsistencies between the photometric and SF definitions provided in the Catalog Archive Server (CAS), and the measurements of targets therein. First, we find that 19.7 deg2 of the DR6 photometric footprint are devoid of MGS targets. In volumes of radii 7 {h}-1 {Mpc}, this can cause errors in the expected number of galaxies to exceed 60%. Second, we identify seven areas that were erroneously included or excluded from the SF. Moreover, the tiling algorithm that positioned spectroscopic fibers during and between DRs caused many areas along the edge of the SF to be significantly undersampled relative to the footprint’s interior. Through our corrections, we increase the completeness 2.2% by trimming 3.6% of the area from the existing SF. The sum total of these efforts has generated the most accurate description of the SDSS DR6 footprints ever created.

The Tully-Fisher relation for 25 000 Sloan Digital Sky Survey galaxies as a function of environment

NASA Astrophysics Data System (ADS)

Mocz, P.; Green, A.; Malacari, M.; Glazebrook, K.

2012-09-01

We construct Tully-Fisher relationships (TFRs) in the u, g, r, i and z bands and stellar mass TFRs for a sample of 25 698 late spiral-type galaxies (with 0.045 < z < 0.085) from the Sloan Digital Sky Survey (SDSS) and study the effects of environment on the relation. We use SDSS-measured Balmer emission line widths, vFWHM, as a proxy for disc circular velocity, vcirc. A priori, it is not clear whether we can construct accurate TFRs given the small 3 arcsec diameter of the fibres used for SDSS spectroscopic measurements. However, we show by modelling the Hα emission profile as observed through a 3 arcsec aperture that for galaxies at appropriate redshifts (z > 0.045) the fibres sample enough of the disc to obtain a linear relationship between vFWHM and vcirc, allowing us to obtain a TFR and to investigate dependence on other variables. We also develop a methodology for distinguishing between astrophysical and sample bias in the fibre TFR trends. We observe the well-known steepening of the TFR in redder bands in our sample. We divide the sample of galaxies into four equal groups using projected neighbour density (Σ) quartiles and find no significant dependence on environment, extending previous work to a wider range of environments and a much larger sample. Having demonstrated that we can construct SDSS-based TFRs is very useful for future TFR studies because of the large sample size available in the SDSS.

A spectroscopic analysis of a sample of narrow-line Seyfert 1 galaxies selected from the Sloan Digital Sky Survey

NASA Astrophysics Data System (ADS)

Cracco, V.; Ciroi, S.; Berton, M.; Di Mille, F.; Foschini, L.; La Mura, G.; Rafanelli, P.

2016-10-01

We revisited the spectroscopic characteristics of narrow-line Seyfert 1 galaxies (NLS1s) by analysing a homogeneous sample of 296 NLS1s at redshift between 0.028 and 0.345, extracted from the Sloan Digital Sky Survey (SDSS-DR7) public archive. We confirm that NLS1s are mostly characterized by Balmer lines with Lorentzian profiles, lower black hole masses and higher Eddington ratios than classic broad-line Seyfert 1 (BLS1s), but they also appear to be active galactic nuclei (AGNs) contiguous with BLS1s and sharing with them common properties. Strong Fe II emission does not seem to be a distinctive property of NLS1s, as low values of Fe II/Hβ are equally observed in these AGNs. Our data indicate that Fe II and Ca II kinematics are consistent with the one of Hβ. On the contrary, O I λ8446 seems to be systematically narrower and it is likely emitted by gas of the broad-line region more distant from the ionizing source and showing different physical properties. Finally, almost all NLS1s of our sample show radial motions of the narrow-line region highly ionized gas. The mechanism responsible for this effect is not yet clear, but there are hints that very fast outflows require high continuum luminosities (>1044 erg s-1) or high Eddington ratios (log (Lbol/LEdd) > -0.1).

LED Street Lighting Solutions: Flagstaff, Arizona as a Case Study

NASA Astrophysics Data System (ADS)

Hall, Jeffrey C.

2018-01-01

Dark-sky protection in Flagstaff, Arizona extends back to 1958, with the first ordinance in the City banning advertising floodlights. The current ordinance, adopted in 1989, is comprehensive and has played a critical role in maintaining the quality of the night sky for astronomy, tourism, public enjoyment, and other purposes. Flagstaff, like many communities around the world, is now working on a transition from legacy bulb-based technology to LED for its outdoor lighting. The City, Lowell Observatory, the U. S. Naval Observatory, and the Flagstaff Dark Skies Coalition have been working intensively for two years to identify an LED-based street lighting solution that will preserve the City's dark skies while meeting municipal needs. We will soon be installing test fixtures for an innovative solution incorporating narrow-band amber LED and modest amounts of low-CCT white LED. In this talk, I will review the types of LEDs available for outdoor lighting and discuss the plans for Flagstaff's street lighting in the LED era, which we hope will be a model for communities worldwide.

Super-sample covariance approximations and partial sky coverage

NASA Astrophysics Data System (ADS)

Lacasa, Fabien; Lima, Marcos; Aguena, Michel

2018-04-01

Super-sample covariance (SSC) is the dominant source of statistical error on large scale structure (LSS) observables for both current and future galaxy surveys. In this work, we concentrate on the SSC of cluster counts, also known as sample variance, which is particularly useful for the self-calibration of the cluster observable-mass relation; our approach can similarly be applied to other observables, such as galaxy clustering and lensing shear. We first examined the accuracy of two analytical approximations proposed in the literature for the flat sky limit, finding that they are accurate at the 15% and 30-35% level, respectively, for covariances of counts in the same redshift bin. We then developed a harmonic expansion formalism that allows for the prediction of SSC in an arbitrary survey mask geometry, such as large sky areas of current and future surveys. We show analytically and numerically that this formalism recovers the full sky and flat sky limits present in the literature. We then present an efficient numerical implementation of the formalism, which allows fast and easy runs of covariance predictions when the survey mask is modified. We applied our method to a mask that is broadly similar to the Dark Energy Survey footprint, finding a non-negligible negative cross-z covariance, i.e. redshift bins are anti-correlated. We also examined the case of data removal from holes due to, for example bright stars, quality cuts, or systematic removals, and find that this does not have noticeable effects on the structure of the SSC matrix, only rescaling its amplitude by the effective survey area. These advances enable analytical covariances of LSS observables to be computed for current and future galaxy surveys, which cover large areas of the sky where the flat sky approximation fails.

Cost-effective handling of digital medical images in the telemedicine environment.

PubMed

Choong, Miew Keen; Logeswaran, Rajasvaran; Bister, Michel

2007-09-01

This paper concentrates on strategies for less costly handling of medical images. Aspects of digitization using conventional digital cameras, lossy compression with good diagnostic quality, and visualization through less costly monitors are discussed. For digitization of film-based media, subjective evaluation of the suitability of digital cameras as an alternative to the digitizer was undertaken. To save on storage, bandwidth and transmission time, the acceptable degree of compression with diagnostically no loss of important data was studied through randomized double-blind tests of the subjective image quality when compression noise was kept lower than the inherent noise. A diagnostic experiment was undertaken to evaluate normal low cost computer monitors as viable viewing displays for clinicians. The results show that conventional digital camera images of X-ray images were diagnostically similar to the expensive digitizer. Lossy compression, when used moderately with the imaging noise to compression noise ratio (ICR) greater than four, can bring about image improvement with better diagnostic quality than the original image. Statistical analysis shows that there is no diagnostic difference between expensive high quality monitors and conventional computer monitors. The results presented show good potential in implementing the proposed strategies to promote widespread cost-effective telemedicine and digital medical environments. 2006 Elsevier Ireland Ltd

A survey for TNOs using the APS POSS I database

NASA Astrophysics Data System (ADS)

Rhoads, E.; Humphries, R.; Woodward, C.; Larsen, J.

2004-12-01

The digitized first epoch Palomar Observatory Sky Survey (POSS I) is an ideal and unused archive for the purpose of data mining Trans-Neptunian Objects (TNOs). When accounting for overlap in TNO phase space and the area of the plates covered by stars and galaxies, the effective sky coverage area for this search was 4931 square degrees for Plutinos, and 4992 square degrees for classical TNOs. Using constraints based on the properties of known TNOs, computer codes were used to separate TNO candidates from millions of stars and galaxies. Lists of possible TNO, Centaur, and asteroid candidates were created. The results of this survey yielded 17 reliable TNOs and TNO candidates, including Pluto, Quaoar, and Varuna. In addition to the TNOs, 28 Centaur and 31 Asteroid candidates were found. The TNO Quaoar was pre-covered, and the Main Belt Asteroid (395) Delia was also recovered. I would like to thank the Minnesota Space Grant Consortium for helping to fund my research.

A Web-based Tool for SDSS and 2MASS Database Searches

NASA Astrophysics Data System (ADS)

Hendrickson, M. A.; Uomoto, A.; Golimowski, D. A.

We have developed a web site using HTML, Php, Python, and MySQL that extracts, processes, and displays data from the Sloan Digital Sky Survey (SDSS) and the Two-Micron All-Sky Survey (2MASS). The goal is to locate brown dwarf candidates in the SDSS database by looking at color cuts; however, this site could also be useful for targeted searches of other databases as well. MySQL databases are created from broad searches of SDSS and 2MASS data. Broad queries on the SDSS and 2MASS database servers are run weekly so that observers have the most up-to-date information from which to select candidates for observation. Observers can look at detailed information about specific objects including finding charts, images, and available spectra. In addition, updates from previous observations can be added by any collaborators; this format makes observational collaboration simple. Observers can also restrict the database search, just before or during an observing run, to select objects of special interest.

Rapid Damage Mapping for the 2015 M7.8 Gorkha Earthquake using Synthetic Aperture Radar Data from COSMO-SkyMed and ALOS-2 Satellites

NASA Astrophysics Data System (ADS)

Yun, S. H.; Hudnut, K. W.; Owen, S. E.; Webb, F.; Simons, M.; Macdonald, A.; Sacco, P.; Gurrola, E. M.; Manipon, G.; Liang, C.; Fielding, E. J.; Milillo, P.; Hua, H.; Coletta, A.

2015-12-01

The April 25, 2015 M7.8 Gorkha earthquake caused more than 8,000 fatalities and widespread building damage in central Nepal. Four days after the earthquake, the Italian Space Agency's (ASI's) COSMO-SkyMed Synthetic Aperture Radar (SAR) satellite acquired data over Kathmandu area. Nine days after the earthquake, the Japan Aerospace Exploration Agency's (JAXA's) ALOS-2 SAR satellite covered larger area. Using these radar observations, we rapidly produced damage proxy maps derived from temporal changes in Interferometric SAR (InSAR) coherence. These maps were qualitatively validated through comparison with independent damage analyses by National Geospatial-Intelligence Agency (NGA) and the UNITAR's (United Nations Institute for Training and Research's) Operational Satellite Applications Programme (UNOSAT), and based on our own visual inspection of DigitalGlobe's WorldView optical pre- vs. post-event imagery. Our maps were quickly released to responding agencies and the public, and used for damage assessment, determining inspection/imaging priorities, and reconnaissance fieldwork.

DESCQA: An Automated Validation Framework for Synthetic Sky Catalogs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mao, Yao-Yuan; Kovacs, Eve; Heitmann, Katrin

The use of high-quality simulated sky catalogs is essential for the success of cosmological surveys. The catalogs have diverse applications, such as investigating signatures of fundamental physics in cosmological observables, understanding the effect of systematic uncertainties on measured signals and testing mitigation strategies for reducing these uncertainties, aiding analysis pipeline development and testing, and survey strategy optimization. The list of applications is growing with improvements in the quality of the catalogs and the details that they can provide. Given the importance of simulated catalogs, it is critical to provide rigorous validation protocols that enable both catalog providers and users tomore » assess the quality of the catalogs in a straightforward and comprehensive way. For this purpose, we have developed the DESCQA framework for the Large Synoptic Survey Telescope Dark Energy Science Collaboration as well as for the broader community. The goal of DESCQA is to enable the inspection, validation, and comparison of an inhomogeneous set of synthetic catalogs via the provision of a common interface within an automated framework. Here in this paper, we present the design concept and first implementation of DESCQA. In order to establish and demonstrate its full functionality we use a set of interim catalogs and validation tests. We highlight several important aspects, both technical and scientific, that require thoughtful consideration when designing a validation framework, including validation metrics and how these metrics impose requirements on the synthetic sky catalogs.« less

DESCQA: An Automated Validation Framework for Synthetic Sky Catalogs

DOE PAGES

Mao, Yao-Yuan; Kovacs, Eve; Heitmann, Katrin; ...

2018-02-08

The use of high-quality simulated sky catalogs is essential for the success of cosmological surveys. The catalogs have diverse applications, such as investigating signatures of fundamental physics in cosmological observables, understanding the effect of systematic uncertainties on measured signals and testing mitigation strategies for reducing these uncertainties, aiding analysis pipeline development and testing, and survey strategy optimization. The list of applications is growing with improvements in the quality of the catalogs and the details that they can provide. Given the importance of simulated catalogs, it is critical to provide rigorous validation protocols that enable both catalog providers and users tomore » assess the quality of the catalogs in a straightforward and comprehensive way. For this purpose, we have developed the DESCQA framework for the Large Synoptic Survey Telescope Dark Energy Science Collaboration as well as for the broader community. The goal of DESCQA is to enable the inspection, validation, and comparison of an inhomogeneous set of synthetic catalogs via the provision of a common interface within an automated framework. Here in this paper, we present the design concept and first implementation of DESCQA. In order to establish and demonstrate its full functionality we use a set of interim catalogs and validation tests. We highlight several important aspects, both technical and scientific, that require thoughtful consideration when designing a validation framework, including validation metrics and how these metrics impose requirements on the synthetic sky catalogs.« less

Probing large-scale structure with large samples of X-ray selected AGN. I. Baryonic acoustic oscillations

NASA Astrophysics Data System (ADS)

Hütsi, Gert; Gilfanov, Marat; Kolodzig, Alexander; Sunyaev, Rashid

2014-12-01

We investigate the potential of large X-ray-selected AGN samples for detecting baryonic acoustic oscillations (BAO). Though AGN selection in X-ray band is very clean and efficient, it does not provide redshift information, and thus needs to be complemented with an optical follow-up. The main focus of this study is (i) to find the requirements needed for the quality of the optical follow-up and (ii) to formulate the optimal strategy of the X-ray survey, in order to detect the BAO. We demonstrate that redshift accuracy of σ0 = 10-2 at z = 1 and the catastrophic failure rate of ffail ≲ 30% are sufficient for a reliable detection of BAO in future X-ray surveys. Spectroscopic quality redshifts (σ0 = 10-3 and ffail ~ 0) will boost the confidence level of the BAO detection by a factor of ~2. For meaningful detection of BAO, X-ray surveys of moderate depth of Flim ~ few 10-15 erg s-1/cm2 covering sky area from a few hundred to ~ten thousand square degrees are required. The optimal strategy for the BAO detection does not necessarily require full sky coverage. For example, in a 1000 day-long survey by an eROSITA type telescope, an optimal strategy would be to survey a sky area of ~9000 deg2, yielding a ~16σ BAO detection. A similar detection will be achieved by ATHENA+ or WFXT class telescopes in a survey with a duration of 100 days, covering a similar sky area. XMM-Newton can achieve a marginal BAO detection in a 100-day survey covering ~400 deg2. These surveys would demand a moderate-to-high cost in terms the optical follow-ups, requiring determination of redshifts of ~105 (XMM-Newton) to ~3 × 106 objects (eROSITA, ATHENA+, and WFXT) in these sky areas.

Evaluation of image quality of digital photo documentation of female genital injuries following sexual assault.

PubMed

Ernst, E J; Speck, Patricia M; Fitzpatrick, Joyce J

2011-12-01

With the patient's consent, physical injuries sustained in a sexual assault are evaluated and treated by the sexual assault nurse examiner (SANE) and documented on preprinted traumagrams and with photographs. Digital imaging is now available to the SANE for documentation of sexual assault injuries, but studies of the image quality of forensic digital imaging of female genital injuries after sexual assault were not found in the literature. The Photo Documentation Image Quality Scoring System (PDIQSS) was developed to rate the image quality of digital photo documentation of female genital injuries after sexual assault. Three expert observers performed evaluations on 30 separate images at two points in time. An image quality score, the sum of eight integral technical and anatomical attributes on the PDIQSS, was obtained for each image. Individual image quality ratings, defined by rating image quality for each of the data, were also determined. The results demonstrated a high level of image quality and agreement when measured in all dimensions. For the SANE in clinical practice, the results of this study indicate that a high degree of agreement exists between expert observers when using the PDIQSS to rate image quality of individual digital photographs of female genital injuries after sexual assault. © 2011 International Association of Forensic Nurses.

76 FR 27973 - Approval and Promulgation of Air Quality Implementation Plans; State of Delaware; Regional Haze...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-05-13

... Ozone National Ambient Air Quality Standard (NAAQS) and the 1997 and 2006 fine particulate matter (PM 2... particle precursors react in the atmosphere to form fine particulate matter, which impairs visibility by... distance, in kilometers or miles, at which a dark object can be viewed against the sky. B. Background...

Current status of Polish Fireball Network

NASA Astrophysics Data System (ADS)

Wiśniewski, M.; Żołądek, P.; Olech, A.; Tyminski, Z.; Maciejewski, M.; Fietkiewicz, K.; Rudawska, R.; Gozdalski, M.; Gawroński, M. P.; Suchodolski, T.; Myszkiewicz, M.; Stolarz, M.; Polakowski, K.

2017-09-01

The Polish Fireball Network (PFN) is a project to monitor regularly the sky over Poland in order to detect bright fireballs. In 2016 the PFN consisted of 36 continuously active stations with 57 sensitive analogue video cameras and 7 high resolution digital cameras. In our observations we also use spectroscopic and radio techniques. A PyFN software package for trajectory and orbit determination was developed. The PFN project is an example of successful participation of amateur astronomers who can provide valuable scientific data. The network is coordinated by astronomers from Copernicus Astronomical Centre in Warsaw, Poland. In 2011-2015 the PFN cameras recorded 214,936 meteor events. Using the PFN data and the UFOOrbit software 34,609 trajectories and orbits were calculated. In the following years we are planning intensive modernization of the PFN network including installation of dozens of new digital cameras.

The element of naturalness when evaluating image quality of digital photo documentation after sexual assault.

PubMed

Ernst, E J; Speck, P M; Fitzpatrick, J J

2012-01-01

Digital photography is a valuable adjunct to document physical injuries after sexual assault. In order for a digital photograph to have high image quality, there must exist a high level of naturalness. Digital photo documentation has varying degrees of naturalness; however, for a photograph to be natural, specific technical elements for the viewer must be satisfied. No tool was available to rate the naturalness of digital photo documentation of female genital injuries after sexual assault. The Photo Documentation Image Quality Scoring System (PDIQSS) tool was developed to rate technical elements for naturalness. Using this tool, experts evaluated randomly selected digital photographs of female genital injuries captured following sexual assault. Naturalness of female genital injuries following sexual assault was demonstrated when measured in all dimensions.

Synthesis method from low-coherence digital holograms for improvement of image quality in holographic display.

PubMed

Mori, Yutaka; Nomura, Takanori

2013-06-01

In holographic displays, it is undesirable to observe the speckle noises with the reconstructed images. A method for improvement of reconstructed image quality by synthesizing low-coherence digital holograms is proposed. It is possible to obtain speckleless reconstruction of holograms due to low-coherence digital holography. An image sensor records low-coherence digital holograms, and the holograms are synthesized by computational calculation. Two approaches, the threshold-processing and the picking-a-peak methods, are proposed in order to reduce random noise of low-coherence digital holograms. The reconstructed image quality by the proposed methods is compared with the case of high-coherence digital holography. Quantitative evaluation is given to confirm the proposed methods. In addition, the visual evaluation by 15 people is also shown.

Toward a Serial International Approach of the High Mountain Observatories, within important Dark Sky Value

NASA Astrophysics Data System (ADS)

Cotte, Michel

2015-08-01

Practical approach of Dark Sky places as possible WH sites leads some of us to underline the exceptional role of high mountain observatories as “Windows to the Universe” for the Human being. Till today, such places keep very important dark sky properties and consequently important astronomical functions.We have to take count that quality of the sky at a given place and dark sky conservation policy is something very important, but not enough by itself to justify inscription on the WH List. It must be related to important cultural or/and natural value. That means presence of significant heritage features in the field of astronomy and science for listing as WH cultural property, or with other natural attributes of exceptional significance to be listed as WH natural property. Case of both natural and cultural WH high value place is also possible as “mixt WH site”.The Dark Sky place must also meet to a sufficient integrity/authenticity degree for the today tangible heritage of astronomy and to a very significant contribution to the international history of science and astronomy as intangible attribute of the place. That point must be demonstrated by a serious comparative analysis with similar places in the world and in the region. In case of serial nomination as examined there, each individual site must contribute significantly to the Outstanding Universal Value of the global series.First, we intend to give a short account of the today trend for a possible serial nomination of the most significant high mountain observatory keeping important heritage of their major periods for the sky observation (Western Europe, Chile, North America, etc.).Second, communication will present a case study with Pic du Midi in French Pyrenees, coming from the early origin of mountain scientific stations and observatories (end of 19th C) in Europe, with a long, continuous and important astronomical and scientific history till today with active programs of sky and atmosphere observations.

Low-cost conversion of the Polaroid MD-4 land camera to a digital gel documentation system.

PubMed

Porch, Timothy G; Erpelding, John E

2006-04-30

A simple, inexpensive design is presented for the rapid conversion of the popular MD-4 Polaroid land camera to a high quality digital gel documentation system. Images of ethidium bromide stained DNA gels captured using the digital system were compared to images captured on Polaroid instant film. Resolution and sensitivity were enhanced using the digital system. In addition to the low cost and superior image quality of the digital system, there is also the added convenience of real-time image viewing through the swivel LCD of the digital camera, wide flexibility of gel sizes, accurate automatic focusing, variable image resolution, and consistent ease of use and quality. Images can be directly imported to a computer by using the USB port on the digital camera, further enhancing the potential of the digital system for documentation, analysis, and archiving. The system is appropriate for use as a start-up gel documentation system and for routine gel analysis.

Quality aspects of digital radiography in general dental practice.

PubMed

Hellén-Halme, Kristina

2007-01-01

The number of dentists who have converted from conventional film radiography to digital radiography continues to grow. A digital system has numerous advantages, but there are also many new aspects to consider. The overall aim of this thesis was to study how digital radiography was used in general dental practices. The specific aims were to study how different factors affected image quality. To determine whether there were any differences in image quality between conventional film radiographs and digital radiographs, 4863 images (540 cases) were evaluated. The cases had been sent to the Swedish Dental Insurance Office for prior treatment approval. The image quality of digital radiographs was found to be significantly lower than that of film radiographs. This result led to a questionnaire study of dentists experienced in digital radiography. In 2003, a questionnaire was sent to the 139 general practice dentists who worked with digital radiography in Skine, Sweden; the response rate was 94%. Many general practice dentists had experienced several problems (65%), and less than half of the digital systems (40%) underwent some kind of quality control. One of the weaker links in the technical chain of digital radiography appeared to be the monitor. A field study to 19 dentists at their clinics found that the brightness and contrast settings of the monitors had to be adjusted to obtain the subjectively best image quality. The ambient light in the evaluation room was also found to affect the diagnostic outcome of low-contrast patterns in radiographs. To evaluate the effects of ambient light and technical adjustments of the monitor, a study using standardised set-ups was designed. Seven observers evaluated radiographs of 100 extracted human teeth for approximal caries under five different combinations of brightness and contrast settings on two different occasions with high and low ambient light levels in the evaluation room. The ability to diagnose carious lesions was found to be significantly better in a room with lower ambient light and on a monitor with well-adjusted brightness and contrast values than in a room with bright light and on an unadjusted monitor. In conclusion, many problems with dental digital radiography were identified. Knowledge of digital techniques and how to optimise each link in the system to maintain high radiographic quality at all times must be improved.

Full-sky Gravitational Lensing Simulation for Large-area Galaxy Surveys and Cosmic Microwave Background Experiments

NASA Astrophysics Data System (ADS)

Takahashi, Ryuichi; Hamana, Takashi; Shirasaki, Masato; Namikawa, Toshiya; Nishimichi, Takahiro; Osato, Ken; Shiroyama, Kosei

2017-11-01

We present 108 full-sky gravitational lensing simulation data sets generated by performing multiple-lens plane ray-tracing through high-resolution cosmological N-body simulations. The data sets include full-sky convergence and shear maps from redshifts z = 0.05 to 5.3 at intervals of 150 {h}-1{Mpc} comoving radial distance (corresponding to a redshift interval of {{Δ }}z≃ 0.05 at the nearby universe), enabling the construction of a mock shear catalog for an arbitrary source distribution up to z = 5.3. The dark matter halos are identified from the same N-body simulations with enough mass resolution to resolve the host halos of the Sloan Digital Sky Survey (SDSS) CMASS and luminous red galaxies (LRGs). Angular positions and redshifts of the halos are provided by a ray-tracing calculation, enabling the creation of a mock halo catalog to be used for galaxy-galaxy and cluster-galaxy lensing. The simulation also yields maps of gravitational lensing deflections for a source redshift at the last scattering surface, and we provide 108 realizations of lensed cosmic microwave background (CMB) maps in which the post-Born corrections caused by multiple light scattering are included. We present basic statistics of the simulation data, including the angular power spectra of cosmic shear, CMB temperature and polarization anisotropies, galaxy-galaxy lensing signals for halos, and their covariances. The angular power spectra of the cosmic shear and CMB anisotropies agree with theoretical predictions within 5% up to {\\ell }=3000 (or at an angular scale θ > 0.5 arcmin). The simulation data sets are generated primarily for the ongoing Subaru Hyper Suprime-Cam survey, but are freely available for download at http://cosmo.phys.hirosaki-u.ac.jp/takahasi/allsky_raytracing/.

Full-sky Gravitational Lensing Simulation for Large-area Galaxy Surveys and Cosmic Microwave Background Experiments

DOE PAGES

Takahashi, Ryuichi; Hamana, Takashi; Shirasaki, Masato; ...

2017-11-14

We present 108 full-sky gravitational lensing simulation data sets generated by performing multiple-lens plane ray-tracing through high-resolution cosmological N-body simulations. The data sets include full-sky convergence and shear maps from redshifts z = 0.05 to 5.3 at intervals ofmore » $$150\\,{h}^{-1}\\mathrm{Mpc}$$ comoving radial distance (corresponding to a redshift interval of $${\\rm{\\Delta }}z\\simeq 0.05$$ at the nearby universe), enabling the construction of a mock shear catalog for an arbitrary source distribution up to z = 5.3. The dark matter halos are identified from the same N-body simulations with enough mass resolution to resolve the host halos of the Sloan Digital Sky Survey (SDSS) CMASS and luminous red galaxies (LRGs). Angular positions and redshifts of the halos are provided by a ray-tracing calculation, enabling the creation of a mock halo catalog to be used for galaxy–galaxy and cluster–galaxy lensing. The simulation also yields maps of gravitational lensing deflections for a source redshift at the last scattering surface, and we provide 108 realizations of lensed cosmic microwave background (CMB) maps in which the post-Born corrections caused by multiple light scattering are included. We present basic statistics of the simulation data, including the angular power spectra of cosmic shear, CMB temperature and polarization anisotropies, galaxy–galaxy lensing signals for halos, and their covariances. The angular power spectra of the cosmic shear and CMB anisotropies agree with theoretical predictions within 5% up to $${\\ell }=3000$$ (or at an angular scale $$\\theta \\gt 0.5$$ arcmin). The simulation data sets are generated primarily for the ongoing Subaru Hyper Suprime-Cam survey, but are freely available for download at http://cosmo.phys.hirosaki-u.ac.jp/takahasi/allsky_raytracing/.« less

Full-sky Gravitational Lensing Simulation for Large-area Galaxy Surveys and Cosmic Microwave Background Experiments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Takahashi, Ryuichi; Hamana, Takashi; Shirasaki, Masato

We present 108 full-sky gravitational lensing simulation data sets generated by performing multiple-lens plane ray-tracing through high-resolution cosmological N-body simulations. The data sets include full-sky convergence and shear maps from redshifts z = 0.05 to 5.3 at intervals ofmore » $$150\\,{h}^{-1}\\mathrm{Mpc}$$ comoving radial distance (corresponding to a redshift interval of $${\\rm{\\Delta }}z\\simeq 0.05$$ at the nearby universe), enabling the construction of a mock shear catalog for an arbitrary source distribution up to z = 5.3. The dark matter halos are identified from the same N-body simulations with enough mass resolution to resolve the host halos of the Sloan Digital Sky Survey (SDSS) CMASS and luminous red galaxies (LRGs). Angular positions and redshifts of the halos are provided by a ray-tracing calculation, enabling the creation of a mock halo catalog to be used for galaxy–galaxy and cluster–galaxy lensing. The simulation also yields maps of gravitational lensing deflections for a source redshift at the last scattering surface, and we provide 108 realizations of lensed cosmic microwave background (CMB) maps in which the post-Born corrections caused by multiple light scattering are included. We present basic statistics of the simulation data, including the angular power spectra of cosmic shear, CMB temperature and polarization anisotropies, galaxy–galaxy lensing signals for halos, and their covariances. The angular power spectra of the cosmic shear and CMB anisotropies agree with theoretical predictions within 5% up to $${\\ell }=3000$$ (or at an angular scale $$\\theta \\gt 0.5$$ arcmin). The simulation data sets are generated primarily for the ongoing Subaru Hyper Suprime-Cam survey, but are freely available for download at http://cosmo.phys.hirosaki-u.ac.jp/takahasi/allsky_raytracing/.« less

GLOBE at Night: a Citizen-Science, Dark Skies Awareness Star Hunt during the International Year of Astronomy

NASA Astrophysics Data System (ADS)

Walker, C. E.; Pompea, S. M.

2008-12-01

GLOBE at Night is an international citizen-science event encouraging everyone, students, the general public, scientists and non-scientists, to measure local levels of light pollution and contribute observations online to a world map. This program is part of the Dark Skies Awareness Global Cornerstone Project for the International Year of Astronomy (IYA) in 2009. Its goal is to raise public awareness of the impact of artificial lighting on local environments by getting people involved. Utilizing the international networks of its hosts, the GLOBE program at UCAR and the National Optical Astronomy Observatory, as well as Astronomical Society of the Pacific, the Association of Science and Technology Centers, the Astronomical League and the International Dark-Sky Association, GLOBE at Night is able to engage people from around the world. Data collection and online reporting is simple and user-friendly. During a 13-day campaign in February or March, citizen-scientists take data on light pollution levels by comparing observations with stellar maps of limiting magnitudes toward the constellation, Orion. For more precise measurements, citizen-scientists use digital sky brightness meters. During the campaign period over the last 3 years, 20,000 measurements from 100 countries have been logged. The collected data is available online in a variety of formats and for comparison with data from previous years, Earth at Night satellite data and population density data. We will discuss how students and scientists worldwide can explore and analyze these results. We will provide the "know-how" and the means for session participants to become community advocates for GLOBE at Night in their hometowns. We will also discuss lessons learned, best practices and campaign plans during IYA (March 16-28, 2009). For more information, visit http://www.globe.gov/GaN/.

Dark Matter Searches in the Gamma-ray Extragalactic Background via Cross-correlations with Galaxy Catalogs

NASA Astrophysics Data System (ADS)

Cuoco, Alessandro; Xia, Jun-Qing; Regis, Marco; Branchini, Enzo; Fornengo, Nicolao; Viel, Matteo

2015-12-01

We compare the measured angular cross-correlation between the Fermi-Large Area Telescope γ-ray sky and catalogs of extragalactic objects with the expected signal induced by weakly interacting massive particle (WIMP) dark matter (DM). We include a detailed description of the contribution of astrophysical γ-ray emitters such as blazars, misaligned active galactic nucleus (AGN), and star-forming galaxies, and perform a global fit to the measured cross-correlation. Five catalogs are considered: Sloan Digital Sky Survey (SDSS)-DR6 quasars, Two Micron All Sky Survey galaxies, NRAO VLA Sky Survey radio galaxies, SDSS-DR8 Luminous Red Galaxies, and the SDSS-DR8 main galaxy sample. To model the cross-correlation signal, we use the halo occupation distribution formalism to estimate the number of galaxies of a given catalog in DM halos and their spatial correlation properties. We discuss uncertainties in the predicted cross-correlation signal arising from the DM clustering and WIMP microscopic properties, which set the DM γ-ray emission. The use of different catalogs probing objects at different redshifts significantly reduces, though not completely, the degeneracy among the different γ-ray components. We find that the presence of a significant WIMP DM signal is allowed by the data but not significantly preferred by the fit, although this is mainly due to a degeneracy with the misaligned AGN component. With modest substructure boost, the sensitivity of this method excludes thermal annihilation cross sections at 95% level for WIMP masses up to few tens of GeV. Constraining the low-redshift properties of astrophysical populations with future data will further improve the sensitivity to DM.

Wild Fire Emissions for the NOAA Operational HYSPLIT Smoke Model

NASA Astrophysics Data System (ADS)

Huang, H. C.; ONeill, S. M.; Ruminski, M.; Shafran, P.; McQueen, J.; DiMego, G.; Kondragunta, S.; Gorline, J.; Huang, J. P.; Stunder, B.; Stein, A. F.; Stajner, I.; Upadhayay, S.; Larkin, N. K.

2015-12-01

Particulate Matter (PM) generated from forest fires often lead to degraded visibility and unhealthy air quality in nearby and downstream areas. To provide near-real time PM information to the state and local agencies, the NOAA/National Weather Service (NWS) operational HYSPLIT (Hybrid Single Particle Lagrangian Integrated Trajectory Model) smoke modeling system (NWS/HYSPLIT smoke) provides the forecast of smoke concentration resulting from fire emissions driven by the NWS North American Model 12 km weather predictions. The NWS/HYSPLIT smoke incorporates the U.S. Forest Service BlueSky Smoke Modeling Framework (BlueSky) to provide smoke fire emissions along with the input fire locations from the NOAA National Environmental Satellite, Data, and Information Service (NESDIS)'s Hazard Mapping System fire and smoke detection system. Experienced analysts inspect satellite imagery from multiple sensors onboard geostationary and orbital satellites to identify the location, size and duration of smoke emissions for the model. NWS/HYSPLIT smoke is being updated to use a newer version of USFS BlueSky. The updated BlueSky incorporates the Fuel Characteristic Classification System version 2 (FCCS2) over the continental U.S. and Alaska. FCCS2 includes a more detailed description of fuel loadings with additional plant type categories. The updated BlueSky also utilizes an improved fuel consumption model and fire emission production system. For the period of August 2014 and June 2015, NWS/HYSPLIT smoke simulations show that fire smoke emissions with updated BlueSky are stronger than the current operational BlueSky in the Northwest U.S. For the same comparisons, weaker fire smoke emissions from the updated BlueSky were observed over the middle and eastern part of the U.S. A statistical evaluation of NWS/HYSPLIT smoke predicted total column concentration compared to NOAA NESDIS GOES EAST Aerosol Smoke Product retrievals is underway. Preliminary results show that using the newer version of BlueSky leads to improved performance of NWS/HYSPLIT-smoke for June 2015. These results are partially due to the default fuel loading selected for Canadian fires that lead to stronger fire emissions there. The use of more realistic Canadian fuel loading may improve NWS/HYSPLIT smoke forecast.

Effect of the position of the visible sky in determining the sky view factor on micrometeorological and human thermal comfort conditions in urban street canyons

NASA Astrophysics Data System (ADS)

Qaid, Adeb; Lamit, Hasanuddin Bin; Ossen, Dilshan Remaz; Rasidi, Mohd Hisyam

2018-02-01

Poor daytime and night-time micrometeorological conditions are issues that influence the quality of environmental conditions and can undermine a comfortable human lifestyle. The sky view factor (SVF) is one of the essential physical parameters used to assess the micrometeorological conditions and thermal comfort levels within city streets. The position of the visible sky relative to the path of the sun, in the cardinal and ordinal directions, has not been widely discerned as a parameter that could have an impact on the micrometeorological conditions of urban streets. To investigate this parameter, different urban streets that have a similar SVF value but diverse positions of visible sky were proposed in different street directions intersecting with the path of the sun, namely N-S, NE-SW and NW-SE. The effects of daytime and night-time micrometeorological variables and human thermal comfort variables on the street were investigated by applying ENVI-met V3.1 Beta software. The results show that the position of the visible sky has a greater influence on the street's meteorological and human thermal comfort conditions than the SVF value. It has the ability to maximise or minimise the mean radiation temperature (Tmrt, °C) and the physiological equivalent temperature (PET, °C) at street level. However, the visible sky positioned to the zenith in a NE-SW or N-S street direction and to the SW of a NW-SE street direction achieves the best daytime micrometeorological and thermal comfort conditions. Alternatively, the visible sky positioned to the NE for a NW-SE street direction, to the NW and the zenith for a NE-SW street direction and to the zenith for a N-S street direction reduces the night-time air temperature (Ta, °C). Therefore, SVF and the position of the visible sky relative to the sun's trajectory, in the cardinal and ordinal directions, must be considered during urban street planning to better understand the resultant micrometeorological and human thermal comfort conditions.

Systematic measurements of the night sky brightness at 26 locations in Eastern Austria

NASA Astrophysics Data System (ADS)

Posch, Thomas; Binder, Franz; Puschnig, Johannes

2018-05-01

We present an analysis of the zenithal night sky brightness (henceforth: NSB) measurements at 26 locations in Eastern Austria focussing on the years 2015-2016, both during clear and cloudy to overcast nights. All measurements have been performed with 'Sky Quality Meters' (SQMs). For some of the locations, simultaneous aerosol content measurements are available, such that we were able to find a correlation between light pollution and air pollution at those stations. For all locations, we examined the circalunar periodicity of the NSB, seasonal variations as well as long-term trends in the recorded light pollution. The latter task proved difficult, however, due to varying meteorological conditions, potential detector 'aging' and other effects. For several remote locations, a darkening of the overcast night sky by up to 1 magnitude is recorded - indicating a very low level of light pollution -, while for the majority of the examined locations, a brightening of the night sky by up to a factor of 15 occurs due to clouds. We present suitable ways to plot and analyze huge long-term NSB datasets, such as mean-NSB histograms, circalunar, annual ('hourglass') and cumulative ('jellyfish') plots. We show that five of the examined locations reach sufficiently low levels of light pollution - with NSB values down to 21.8 magSQM/arcsec2 - as to allow the establishment of dark sky reserves, even to the point of reaching the 'gold tier' defined by the International Dark Sky Association. Based on the 'hourglass' plots, we find a strong circalunar periodicity of the NSB in small towns and villages ( < 5.000 inhabitants), with amplitudes of up to 5 magnitudes. Using the 'jellyfish' plots, on the other hand, we demonstrate that the examined city skies brighten by up to 3 magnitudes under cloudy conditions, which strongly dominate in those cumulative data representations. Nocturnal gradients of the NSB of 0.0-0.14 magSQM/arcsec2/h are found. The long-term development of the night sky brightness was evaluated based on the 2012-17 data for one of our sites, possibly indicating a slight ( 2%) decrease of the mean zenithal NSB at the Vienna University Observatory.

Multivariate Statistical Analysis Software Technologies for Astrophysical Research Involving Large Data Bases

NASA Technical Reports Server (NTRS)

Djorgovski, S. G.

1994-01-01

We developed a package to process and analyze the data from the digital version of the Second Palomar Sky Survey. This system, called SKICAT, incorporates the latest in machine learning and expert systems software technology, in order to classify the detected objects objectively and uniformly, and facilitate handling of the enormous data sets from digital sky surveys and other sources. The system provides a powerful, integrated environment for the manipulation and scientific investigation of catalogs from virtually any source. It serves three principal functions: image catalog construction, catalog management, and catalog analysis. Through use of the GID3* Decision Tree artificial induction software, SKICAT automates the process of classifying objects within CCD and digitized plate images. To exploit these catalogs, the system also provides tools to merge them into a large, complex database which may be easily queried and modified when new data or better methods of calibrating or classifying become available. The most innovative feature of SKICAT is the facility it provides to experiment with and apply the latest in machine learning technology to the tasks of catalog construction and analysis. SKICAT provides a unique environment for implementing these tools for any number of future scientific purposes. Initial scientific verification and performance tests have been made using galaxy counts and measurements of galaxy clustering from small subsets of the survey data, and a search for very high redshift quasars. All of the tests were successful and produced new and interesting scientific results. Attachments to this report give detailed accounts of the technical aspects of the SKICAT system, and of some of the scientific results achieved to date. We also developed a user-friendly package for multivariate statistical analysis of small and moderate-size data sets, called STATPROG. The package was tested extensively on a number of real scientific applications and has produced real, published results.

Digital seismo-acoustic signal processing aboard a wireless sensor platform

NASA Astrophysics Data System (ADS)

Marcillo, O.; Johnson, J. B.; Lorincz, K.; Werner-Allen, G.; Welsh, M.

2006-12-01

We are developing a low power, low-cost wireless sensor array to conduct real-time signal processing of earthquakes at active volcanoes. The sensor array, which integrates data from both seismic and acoustic sensors, is based on Moteiv TMote Sky wireless sensor nodes (www.moteiv.com). The nodes feature a Texas Instruments MSP430 microcontroller, 48 Kbytes of program memory, 10 Kbytes of static RAM, 1 Mbyte of external flash memory, and a 2.4-GHz Chipcon CC2420 IEEE 802.15.4 radio. The TMote Sky is programmed in TinyOS. Basic signal processing occurs on an array of three peripheral sensor nodes. These nodes are tied into a dedicated GPS receiver node, which is focused on time synchronization, and a central communications node, which handles data integration and additional processing. The sensor nodes incorporate dual 12-bit digitizers sampling a seismic sensor and a pressure transducer at 100 samples per second. The wireless capabilities of the system allow flexible array geometry, with a maximum aperture of 200m. We have already developed the digital signal processing routines on board the Moteiv Tmote sensor nodes. The developed routines accomplish Real-time Seismic-Amplitude Measurement (RSAM), Seismic Spectral- Amplitude Measurement (SSAM), and a user-configured Short Term Averaging / Long Term Averaging (STA LTA ratio), which is used to calculate first arrivals. The processed data from individual nodes are transmitted back to a central node, where additional processing may be performed. Such processing will include back azimuth determination and other wave field analyses. Future on-board signal processing will focus on event characterization utilizing pattern recognition and spectral characterization. The processed data is intended as low bandwidth information which can be transmitted periodically and at low cost through satellite telemetry to a web server. The processing is limited by the computational capabilities (RAM, ROM) of the nodes. Nevertheless, we envision this product to be a useful tool for assessing the state of unrest at remote volcanoes.

A Galaxy Zoo - WorldWide Telescope Mashup: Expanding User Defined Exploration

NASA Astrophysics Data System (ADS)

Luebbert, Jarod; Sands, M.; Fay, J.; Smith, A.; Gay, P. L.; Galaxy Zoo Team

2010-01-01

We present a new way of exploring your favorite Galaxy Zoo galaxies within the context of the sky using Microsoft Research's WorldWide Telescope. Galaxy Zoo has a fantastic community that is eager to learn and contribute to science through morphological classifications of galaxies. WorldWide Telescope is an interactive observatory that allows users to explore the sky. WorldWide Telescope uses images from the world's best telescopes, including the galaxies of the Sloan Digital Sky Survey. WorldWide Telescope provides a fantastic sense of size and distance that is hard to experience in Galaxy Zoo. Creating tours from favorite galaxies directly from Galaxy Zoo aims to solve this dilemma.The incorporation of Galaxy Zoo and WorldWide telescope provides a great resource for users to learn more about the galaxies they are classifying. Users can now explore the areas around certain galaxies and view information about that location from within WorldWide Telescope. Not only does this encourage self-motivated research but after tours are created they can be shared with anyone. We hope this will help spread citizen science to different audiences via email, Facebook, and Twitter.Without the WorldWide Telescope team at Microsoft Research this project would not have been possible. Please go start exploring at http://wwt.galaxyzoo.org. This project was funded through the Microsoft Research Academic Program.

Instrumental Response Model and Detrending for the Dark Energy Camera

DOE PAGES

Bernstein, G. M.; Abbott, T. M. C.; Desai, S.; ...

2017-09-14

We describe the model for mapping from sky brightness to the digital output of the Dark Energy Camera (DECam) and the algorithms adopted by the Dark Energy Survey (DES) for inverting this model to obtain photometric measures of celestial objects from the raw camera output. This calibration aims for fluxes that are uniform across the camera field of view and across the full angular and temporal span of the DES observations, approaching the accuracy limits set by shot noise for the full dynamic range of DES observations. The DES pipeline incorporates several substantive advances over standard detrending techniques, including principal-components-based sky and fringe subtraction; correction of the "brighter-fatter" nonlinearity; use of internal consistency in on-sky observations to disentangle the influences of quantum efficiency, pixel-size variations, and scattered light in the dome flats; and pixel-by-pixel characterization of instrument spectral response, through combination of internal-consistency constraints with auxiliary calibration data. This article provides conceptual derivations of the detrending/calibration steps, and the procedures for obtaining the necessary calibration data. Other publications will describe the implementation of these concepts for the DES operational pipeline, the detailed methods, and the validation that the techniques can bring DECam photometry and astrometry withinmore » $$\\approx 2$$ mmag and $$\\approx 3$$ mas, respectively, of fundamental atmospheric and statistical limits. In conclusion, the DES techniques should be broadly applicable to wide-field imagers.« less

Instrumental Response Model and Detrending for the Dark Energy Camera

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bernstein, G. M.; Abbott, T. M. C.; Desai, S.

We describe the model for mapping from sky brightness to the digital output of the Dark Energy Camera (DECam) and the algorithms adopted by the Dark Energy Survey (DES) for inverting this model to obtain photometric measures of celestial objects from the raw camera output. This calibration aims for fluxes that are uniform across the camera field of view and across the full angular and temporal span of the DES observations, approaching the accuracy limits set by shot noise for the full dynamic range of DES observations. The DES pipeline incorporates several substantive advances over standard detrending techniques, including principal-components-based sky and fringe subtraction; correction of the "brighter-fatter" nonlinearity; use of internal consistency in on-sky observations to disentangle the influences of quantum efficiency, pixel-size variations, and scattered light in the dome flats; and pixel-by-pixel characterization of instrument spectral response, through combination of internal-consistency constraints with auxiliary calibration data. This article provides conceptual derivations of the detrending/calibration steps, and the procedures for obtaining the necessary calibration data. Other publications will describe the implementation of these concepts for the DES operational pipeline, the detailed methods, and the validation that the techniques can bring DECam photometry and astrometry withinmore » $$\\approx 2$$ mmag and $$\\approx 3$$ mas, respectively, of fundamental atmospheric and statistical limits. In conclusion, the DES techniques should be broadly applicable to wide-field imagers.« less

A Method for Assessing the Quality of Model-Based Estimates of Ground Temperature and Atmospheric Moisture Using Satellite Data

NASA Technical Reports Server (NTRS)

Wu, Man Li C.; Schubert, Siegfried; Lin, Ching I.; Stajner, Ivanka; Einaudi, Franco (Technical Monitor)

2000-01-01

A method is developed for validating model-based estimates of atmospheric moisture and ground temperature using satellite data. The approach relates errors in estimates of clear-sky longwave fluxes at the top of the Earth-atmosphere system to errors in geophysical parameters. The fluxes include clear-sky outgoing longwave radiation (CLR) and radiative flux in the window region between 8 and 12 microns (RadWn). The approach capitalizes on the availability of satellite estimates of CLR and RadWn and other auxiliary satellite data, and multiple global four-dimensional data assimilation (4-DDA) products. The basic methodology employs off-line forward radiative transfer calculations to generate synthetic clear-sky longwave fluxes from two different 4-DDA data sets. Simple linear regression is used to relate the clear-sky longwave flux discrepancies to discrepancies in ground temperature ((delta)T(sub g)) and broad-layer integrated atmospheric precipitable water ((delta)pw). The slopes of the regression lines define sensitivity parameters which can be exploited to help interpret mismatches between satellite observations and model-based estimates of clear-sky longwave fluxes. For illustration we analyze the discrepancies in the clear-sky longwave fluxes between an early implementation of the Goddard Earth Observing System Data Assimilation System (GEOS2) and a recent operational version of the European Centre for Medium-Range Weather Forecasts data assimilation system. The analysis of the synthetic clear-sky flux data shows that simple linear regression employing (delta)T(sub g)) and broad layer (delta)pw provides a good approximation to the full radiative transfer calculations, typically explaining more thin 90% of the 6 hourly variance in the flux differences. These simple regression relations can be inverted to "retrieve" the errors in the geophysical parameters, Uncertainties (normalized by standard deviation) in the monthly mean retrieved parameters range from 7% for (delta)T(sub g) to approx. 20% for the lower tropospheric moisture between 500 hPa and surface. The regression relationships developed from the synthetic flux data, together with CLR and RadWn observed with the Clouds and Earth Radiant Energy System instrument, ire used to assess the quality of the GEOS2 T(sub g) and pw. Results showed that the GEOS2 T(sub g) is too cold over land, and pw in upper layers is too high over the tropical oceans and too low in the lower atmosphere.

VizieR Online Data Catalog: MWSC IV. 63 new open clusters (Scholz+, 2015)

NASA Astrophysics Data System (ADS)

Scholz, R.-D.; Kharchenko, N. V.; Piskunov, A. E.; Roeser, S.; Schilbach, E.

2015-08-01

We first selected high-quality samples from the 2MAst and UCAC4 catalogues for comparison and verification of the proper motions. For 441 circular proper motion bins (radius 15mas/yr) within+/-50mas/yr, the sky outside a thin Galactic plane zone (|b|<5°) was binned in small areas ('sky pixels') of 0.25x0.25°2, Sky pixels with enhanced numbers of stars with a certain common proper motion in both catalogues were considered as cluster candidates. In total we discovered 692 density enhancements (regarded as cluster candidates). These candidates were cross-identified with known objects. Unidentified objects were passed through the standard MWSC pipeline (described in Kharchenko et al., 2012, Cat. J/A+A/543/A156) for verification, cluster membership construction and structure, kinematic and astrophysical parameter determination. The basic stellar data were taken from the all-sky catalogue 2MAst (2MASS with Astrometry), that was extracted from the all-sky catalogues PPMXL (Roeser et al. 2010, Cat.) and 2MASS (Cutri et al. 2003, Cat.). We found that 355 candidates coincide or overlap with known objects. From the remaining candidates, 270 could not be confirmed by the MWSC pipeline, whereas 63 were classified as real star clusters, for which we determined their basic cluster parameters. Around each confirmed object from our target list we defined a circular area with a radius of ra=r2+radd where r2 is an initial estimate of the cluster radius, and radd=0.3deg. In these areas we selected in 2MAst only those stars with flags Rflg (the 2nd triple of the flags in 2MASS) set to 1, 2, or 3 in each band, i.e. the stars with the best quality detections in photometric and astrometric data. The 63 sky areas with confirmed clusters contain about 0.49 mln 2MAst stars with best quality detections in photometric and astrometric data. We selected most probable members and determined - with a homogeneous method/pipeline - angular sizes of the main morphological parts, heliocentric distances, colour-excesses, mean proper motions, ages, tidal parameters. This work represents the second extension of the MWSC survey (Kharchenko et al. 2012, Cat. J/A+A/543/A156, 2013, Cat. J/A+A/558/A53), which had an original input list of 3784 targets. After the first extension by Schmeja et al. (2014, Cat. J/A+A/568/A51), who investigated 782 further candidates, we analysed 692 new candidates. We have adopted for them MWSC numbers starting with 4001. We present: The Catalogue of 63 new MWSC open clusters, which includes several files: Catalogue of cluster parameters (confirmed clusters only); Index of all 692 candidates; Notes for every item of the index list. Within each list the entries are ordered by the MWSC number. The Catalogues of the MWSC Stars in 63 circular sky areas with confirmed clusters. Files are ordered by MWSC number; inside each sky area the entries are ordered by Ks magnitudes. The Atlas of 63 new MWSC clusters diagrams. In the Atlas the Cluster pages are ordered by MWSC number. All the data are given in the same format as in the main MWSC catalogue (J/A+A/558/A53). (5 data files).