Large-scale structure in the Southern Sky Redshift Survey

NASA Technical Reports Server (NTRS)

Park, Changbom; Gott, J. R., III; Da Costa, L. N.

1992-01-01

The power spectrum from the Southern Sky Redshift Survey and the CfA samples are measured in order to explore the amplitude of fluctuation in the galaxy density. At lambda of less than or equal to 30/h Mpc the observed power spectrum is quite consistent with the standard CDM model. At larger scales the data indicate an excess of power over the standard CDM model. The observed power spectrum from these optical galaxy samples is in good agreement with that drawn from the sparsely sampled IRAS galaxies. The shape of the power spectrum is also studied by examining the relation between the genus per unit volume and the smoothing length. It is found that, over Gaussian smoothing scales from 6 to 14/h Mpc, the power spectrum has a slope of about -1. The topology of the galaxy density field is studied by measuring the shift of the genus curve from the Gaussian case. Over all smoothing scales studied, the observed genus curves are consistent with a random phase distribution of the galaxy density field, as predicted by the inflationary scenarios.

The Southern Argentina Agile Meteor Radar Orbital System (SAAMER-OS): An Initial Sporadic Meteoroid Orbital Survey in the Southern Sky

NASA Technical Reports Server (NTRS)

Janches, D.; Close, S.; Hormaechea, J. L.; Swarnalingam, N.; Murphy, A.; O'Connor, D.; Vandepeer, B.; Fuller, B.; Fritts, D. C.; Brunini, C.

2015-01-01

We present an initial survey in the southern sky of the sporadic meteoroid orbital environment obtained with the Southern Argentina Agile MEteor Radar (SAAMER) Orbital System (OS), in which over three-quarters of a million orbits of dust particles were determined from 2012 January through 2015 April. SAAMER-OS is located at the southernmost tip of Argentina and is currently the only operational radar with orbit determination capability providing continuous observations of the southern hemisphere. Distributions of the observed meteoroid speed, radiant, and heliocentric orbital parameters are presented, as well as those corrected by the observational biases associated with the SAAMER-OS operating parameters. The results are compared with those reported by three previous surveys performed with the Harvard Radio Meteor Project, the Advanced Meteor Orbit Radar, and the Canadian Meteor Orbit Radar, and they are in agreement with these previous studies. Weighted distributions for meteoroids above the thresholds for meteor trail electron line density, meteoroid mass, and meteoroid kinetic energy are also considered. Finally, the minimum line density and kinetic energy weighting factors are found to be very suitable for meteoroid applications. The outcomes of this work show that, given SAAMERs location, the system is ideal for providing crucial data to continuously study the South Toroidal and South Apex sporadic meteoroid apparent sources.

THE SOUTHERN ARGENTINA AGILE METEOR RADAR ORBITAL SYSTEM (SAAMER-OS): AN INITIAL SPORADIC METEOROID ORBITAL SURVEY IN THE SOUTHERN SKY

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

Janches, D.; Swarnalingam, N.; Close, S.

2015-08-10

We present an initial survey in the southern sky of the sporadic meteoroid orbital environment obtained with the Southern Argentina Agile MEteor Radar (SAAMER) Orbital System (OS), in which over three-quarters of a million orbits of dust particles were determined from 2012 January through 2015 April. SAAMER-OS is located at the southernmost tip of Argentina and is currently the only operational radar with orbit determination capability providing continuous observations of the southern hemisphere. Distributions of the observed meteoroid speed, radiant, and heliocentric orbital parameters are presented, as well as those corrected by the observational biases associated with the SAAMER-OS operatingmore » parameters. The results are compared with those reported by three previous surveys performed with the Harvard Radio Meteor Project, the Advanced Meteor Orbit Radar, and the Canadian Meteor Orbit Radar, and they are in agreement with these previous studies. Weighted distributions for meteoroids above the thresholds for meteor trail electron line density, meteoroid mass, and meteoroid kinetic energy are also considered. Finally, the minimum line density and kinetic energy weighting factors are found to be very suitable for meteroid applications. The outcomes of this work show that, given SAAMER’s location, the system is ideal for providing crucial data to continuously study the South Toroidal and South Apex sporadic meteoroid apparent sources.« less

Promoting Dark Sky Protection in Chile: the Gabriel Mistral IDA Dark Sky Sanctuary and Other AURA Initiatives

NASA Astrophysics Data System (ADS)

Smith, R. Chris; Smith, Malcolm; Pompea, Stephen; Sanhueza, Pedro; AURA-Chile EPO Team

2018-01-01

For over 20 years, AURA has been leading efforts promoting the protection of dark skies in northern Chile. Efforts began in the early 1990s at AURA's Cerro Tololo Inter-American Observatory (CTIO), working in collaboration with other international observatories in Chile including Las Campanas Observatory (LCO) and the European Southern Observatory (ESO). CTIO also partnered with local communities, for example supporting Vicuña's effort to establish the first municipal observatory in Chile. Today we have developed a multifaceted effort of dark sky protection, including proactive government relations at national and local levels, a strong educational and public outreach program, and a program of highlighting international recognition of the dark skies through the IDA Dark Sky Places program. Work on international recognition has included the declaration of the Gabriel Mistral IDA Dark Sky Sanctuary, the first such IDA sanctuary in the world.

The Infrared Sky: A Survey of Surveys

DTIC Science & Technology

1988-02-01

that thme IT instru- c’Orr.Sponding spectral types. Thus, Hall (1961) recog- went would be imore productive iii thme Southern Henii- milted relati~el...the southern sky began in February 1967 unider AFCHL Iroam thevir % isual appearanice", A comiclusion concurrently sponsorship but unusually poor...survey is theonly exteisive iear-infrared diechnations between - 330 and - 469; the most southerly Southern Hemisphere survey to date with published re

Explorers of the Southern Sky

NASA Astrophysics Data System (ADS)

Haynes, Raymond; Haynes, Roslynn D.; Malin, David; McGee, Richard

2010-08-01

Preface; Acknowledgements; 1. Dreaming the stars; 2. Sailing south for a new sky; 3. Astronomy in Sydney town; 4. The struggle for independence; 5. A bid for fame; 6. For love of the subject; 7. Astronomy on a national basis; 8. From swords to ploughshares; 9. Radio astronomy and the big telescopes; 10. Entrepreneurs in astronomy; 11. The advantage of latitude; 12. The high-energy frontier; 13. Diversity through innovation; 14. Optical astronomy goes high tech; 15. A telescope as wide as a continent; Glossary of abbreviations; Glossary of scientific and technical words; Bibliography; Index of names and dates; Subject index.

Lightcurve Analysis of Minor Planets Observed at the Oakley Southern Sky Observatory: 2016 October - 2017 March

NASA Astrophysics Data System (ADS)

Ditteon, Richard; Adam, Andre; Doyel, Michael; Gibson, Jared; Lee, Stephanie; Linville, Dylan; Michalik, Danielle; Turner, Rhiannon; Washburn, Kyle

2018-01-01

From 2016 October 28 to 2017 March 9, CCD images were taken with the goal of analyzing the photometric data on 34 minor planets: 393 Lampetia, 395 Delia, 838 Seraphina, 874 Rotraut, 1114 Lorraine, 1128 Astrid, 1465 Autonoma, 1529 Oterma, 1722 Goffin, 1773 Rumpelstilz, 1903 Adzhimushkaj, 2685 Masursky, 2916 Voronveliya, 2928 Epstein, 2973 Paola, 3032 Evans, 3104 Durer, 3224 Irkutsk, 3532 Tracie, 3569 Kumon, 4112 Hrabal, 4512 Sinuhe, 4695 Mediolanum, 4945 Ikenozenni, 5240 Kwasan, 5625 Jamesferguson, 6199 Yoshiokayayoi, 7001 Noether, 11127 Hagi, 11441 Anadiego, 15267 Kolyma, (18429) 1994 AO1, (24814) 1994 VW1, and (326683) 2002 WP.

Some non-atlas work at ESO Sky Atlas Laboratory.

NASA Astrophysics Data System (ADS)

Madsen, C.

The ESO Sky Atlas Laboratory (SAL) was set up in 1972 with the aim of producing the ESO Quick Blue Survey and later the joint ESO/SERC Survey of the Southern Sky. With the establishment of a Scientific Group, it became apparent that ESO had additional photographic needs, the fullfilment of which was also entrusted to SAL. Thus, in the course of the years, the "Photographic Section" evolved as a subdivision of the Sky Atlas Laboratory.

GASS: the Parkes Galactic all-sky survey. II. Stray-radiation correction and second data release

NASA Astrophysics Data System (ADS)

Kalberla, P. M. W.; McClure-Griffiths, N. M.; Pisano, D. J.; Calabretta, M. R.; Ford, H. Alyson; Lockman, F. J.; Staveley-Smith, L.; Kerp, J.; Winkel, B.; Murphy, T.; Newton-McGee, K.

2010-10-01

Context. The Parkes Galactic all-sky survey (GASS) is a survey of Galactic atomic hydrogen (H i) emission in the southern sky observed with the Parkes 64-m Radio Telescope. The first data release was published by McClure-Griffiths et al. (2009). Aims: We remove instrumental effects that affect the GASS and present the second data release. Methods: We calculate the stray-radiation by convolving the all-sky response of the Parkes antenna with the brightness temperature distribution from the Leiden/Argentine/Bonn (LAB) all sky 21-cm line survey, with major contributions from the 30-m dish of the Instituto Argentino de Radioastronomía (IAR) in the southern sky. Remaining instrumental baselines are corrected using the LAB data for a first guess of emission-free baseline regions. Radio frequency interference is removed by median filtering. Results: After applying these corrections to the GASS we find an excellent agreement with the Leiden/Argentine/Bonn (LAB) survey. The GASS is the highest spatial resolution, most sensitive, and is currently the most accurate H i survey of the Galactic H i emission in the southern sky. We provide a web interface for generation and download of FITS cubes.

Nightscape Photography Reclaims the Natural Sky

NASA Astrophysics Data System (ADS)

Tafreshi, Babak

2015-08-01

Nightscape photos and timelapse videos, where the Earth & sky are framed together with an astronomical purpose, support the dark skies activities by improving public awareness. TWAN or The World at Night program (www.twanight.org) presents the world's best collection of such landscape astrophotos and aims to introduce the night sky as a part of nature, an essential element of our living environment besides being the astronomers lab. The nightscape images also present views of our civilizations landmarks, both natural and historic sites, against the night-time backdrop of stars, planets, and celestial events. In this context TWAN is a bridge between art, science and culture.TWAN images contribute to programs such as the Dark Sky Parks by the International Dark Sky Association or Starlight reserves by assisting local efforts in better illustrating their dark skies and by producing stunning images that not only educate the local people on their night sky heritage also communicate with the governments that are responsible to support the dark sky area.Since 2009 TWAN organizes the world's largest annual photo contest on nightscape imaging, in collaboration with the Dark Skies Awareness, National Optical Astronomy Observatory, and Astronomers Without Borders. The International Earth & Sky Photo Contest promotes the photography that documents the beauty of natural skies against the problem of light pollution. In 2014 the entries received from about 50 countries and the contest result news was widely published in the most popular sources internationally.*Babak A. Tafreshi is a photographer and science communicator. He is the creator of The World At Night program, and a contributing photographer to the National Geographic, Sky&Telescope magazine, and the European Southern Observatory. http://twanight.org/tafreshi

The Status of the NASA All Sky Fireball Network

NASA Technical Reports Server (NTRS)

Cooke, William J.; Moser, Danielle E.

2011-01-01

Established by the NASA Meteoroid Environment Office, the NASA All Sky Fireball Network consists of 6 meteor video cameras in the southern United States, with plans to expand to 15 cameras by 2013. As of mid-2011, the network had detected 1796 multi-station meteors, including meteors from 43 different meteor showers. The current status of the NASA All Sky Fireball Network is described, alongside preliminary results.

Absolute parameters of eclipsing binaries in Southern Hemisphere sky - II: QY Tel

NASA Astrophysics Data System (ADS)

Erdem, A.; Sürgit, D.; Engelbrecht, C. A.; van Heerden, H. P.; Manick, R.

2016-11-01

This paper presents the first analysis of spectroscopic and photometric observations of the neglected southern eclipsing binary star, QY Tel. Spectroscopic observations were carried out at the South African Astronomical Observatory in 2013. New radial velocity curves from this study and V light curves from the All Sky Automated Survey were solved simultaneously using modern light and radial velocity curve synthesis methods. The final model describes QY Tel as a detached binary star where both component stars fill at least half of their Roche limiting lobes. The masses and radii were found to be 1.32 (± 0.06) M⊙, 1.74 (± 0.15) R⊙ and 1.44 (± 0.09) M⊙, 2.70 (± 0.16) R⊙ for the primary and secondary components of the system, respectively. The distance to QY Tel was calculated as 365 (± 40) pc, taking into account interstellar extinction. The evolution case of QY Tel is also examined. Both components of the system are evolved main-sequence stars with an age of approximately 3.2 Gy, when compared to Geneva theoretical evolution models.

C-BASS: The C-Band All Sky Survey

NASA Astrophysics Data System (ADS)

Pearson, Timothy J.; C-BASS Collaboration

2016-06-01

The C-Band All Sky Survey (C-BASS) is a project to image the whole sky at a wavelength of 6 cm (frequency 5 GHz), measuring both the brightness and the polarization of the sky. Correlation polarimeters are mounted on two separate telescopes, one at the Owens Valley Observatory (OVRO) in California and another in South Africa, allowing C-BASS to map the whole sky. The OVRO instrument has completed observations for the northern part of the survey. We are working on final calibration of intensity and polarization. The southern instrument has recently started observations for the southern part of the survey from its site at Klerefontein near Carnarvon in South Africa. The principal aim of C-BASS is to allow the subtraction of polarized Galactic synchrotron emission from the data produced by CMB polarization experiments, such as WMAP, Planck, and dedicated B-mode polarization experiments. In addition it will contribute to studies of: (1) the local (< 1 kpc) Galactic magnetic field and cosmic-ray propagation; (2) the distribution of the anomalous dust emission, its origin and the physical processes that affect it; (3) modeling of Galactic total intensity emission, which may allow CMB experiments access to the currently inaccessible region close to the Galactic plane. Observations at many wavelengths from radio to infrared are needed to fully understand the foregrounds. At 5 GHz, C-BASS maps synchrotron polarization with minimal corruption by Faraday rotation, and complements the full-sky maps from WMAP and Planck. I will present the project status, show results of component separation in selected sky regions, and describe the northern survey data products.C-BASS (http://www.astro.caltech.edu/cbass/) is a collaborative project between the Universities of Oxford and Manchester in the UK, the California Institute of Technology (supported by the National Science Foundation and NASA) in the USA, the Hartebeesthoek Radio Astronomy Observatory (supported by the Square Kilometre

Absolute parameters of detached binaries in the southern sky - III: HO Tel

NASA Astrophysics Data System (ADS)

Sürgit, D.; Erdem, A.; Engelbrecht, C. A.; van Heerden, H. P.; Manick, R.

2017-07-01

We present the first radial velocity analysis of the southern eclipsing binary star HO Tel, based on spectra obtained at the South African Astronomical Observatory in 2013. The orbital solution of this neglected binary gave the quite large spectroscopic mass ratio of 0.921(±0.005). The V light curve from the All Sky Automated Survey (ASAS) and Walraven five-colour (WULBV) photometric light curves (Spoelstra and Van Houten 1972) were solved simultaneously using the Wilson-Devinney code supplemented by the Monte Carlo search method. The final photometric model describes HO Tel as a detached binary star where both component stars fill about three-quarters of their Roche limiting lobes. The masses and radii were found to be 1.88(±0.04) M⊙, 2.28(±0.15) R⊙ and 1.73(±0.04) M⊙, 2.08(±0.16) R⊙ for the primary and secondary components of the system, respectively. The distance to HO Tel was calculated as 282(±30) pc, taking into account interstellar extinction. The evolution case of HO Tel was also examined. Both components of the system are evolved main-sequence stars with an age of approximately 1.1 Gy, when compared to Geneva theoretical evolution models.

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.

Biasing and High-Order Statistics from the Southern-Sky Redshift Survey

NASA Astrophysics Data System (ADS)

Benoist, C.; Cappi, A.; da Costa, L. N.; Maurogordato, S.; Bouchet, F. R.; Schaeffer, R.

1999-04-01

We analyze different volume-limited samples extracted from the Southern-Sky Redshift Survey (SSRS2), using counts-in-cells to compute the count probability distribution function (CPDF). From the CPDF we derive volume-averaged correlation functions to fourth order and the normalized skewness and kurtosis S3=ξ3¯/ξ¯22 and S4=ξ4¯/ξ¯32. We find that the data satisfies the hierarchical relations in the range 0.3<~ξ2¯<~10. In this range we find S3 to be scale independent, with a value of ~1.8, in good agreement with the values measured from other optical redshift surveys probing different volumes, but significantly smaller than that inferred from the Automatic Plate Measuring Facility (APM) angular catalog. In addition, the measured values of S3 do not show a significant dependence on the luminosity of the galaxies considered. This result is supported by several tests of systematic errors that could affect our measures and estimates of the cosmic variance determined from mock catalogs extracted from N-body simulations. This result is in marked contrast to what would be expected from the strong dependence of the two-point correlation function on luminosity in the framework of a linear biasing model. We discuss the implications of our results and compare them to some recent models of the galaxy distribution that address the problem of bias.

2MASS - The 2 Micron All Sky Survey

NASA Technical Reports Server (NTRS)

Kleinmann, S. G.

1992-01-01

This paper describes a new sky survey to be carried out in three wavebands, J(1.25 m), H(1.65 m), and K(2.2 m). The limiting sensitivity of the survey, 10 sigma detection of point sources with K not greater than 14 mag, coupled with its all-sky coverage, were selected primarily to support studies of the large-scale structure of the Milky Way and the Local Universe. The survey requires construction of a pair of observing facilities, one each for the Northern and Southern Hemispheres. Operations are scheduled to begin in 1995. The data will begin becoming publicly available soon thereafter.

Exploring the Night Sky with Binoculars

NASA Astrophysics Data System (ADS)

Moore, Patrick

On a clear, starry night, the jewelled beauty and unimaginable immensity of our Universe is awe-inspiring. Star-gazing with binoculars is rewarding and may begin a lifelong hobby! Patrick Moore has painstakingly researched Exploring the Night Sky with Binoculars to describe how to use binoculars for astronomical observation. He explains basic astronomy and the selection of binoculars, then discusses the stars, clusters, nebulae and galaxies that await the observer. The sky seen from northern and southern hemispheres is charted season by season, with detailed maps of all the constellations. The reader can also observe the Sun, Moon, planets, comets and meteors. With many beautiful illustrations, this handbook will be helpful and encouraging to casual observers and those cultivating a more serious interest. The enjoyment of amateur astronomy is now available to everybody.

Flying between sky islands: the effect of naturally fragmented habitat on butterfly population structure.

PubMed

Sekar, Sandhya; Karanth, Praveen

2013-01-01

High elevation montane areas are called "sky islands" when they occur as a series of high mountains separated by lowland valleys. Different climatic conditions at high elevations makes sky islands a specialized type of habitat, rendering them naturally fragmented compared to more continuous habitat at lower elevations. Species in sky islands face unsuitable climate in the intervening valleys when moving from one montane area to another. The high elevation shola-grassland mosaic in the Western Ghats of southern India form one such sky island complex. The fragmented patches make this area ideal to study the effect of the spatial orientation of suitable habitat patches on population genetic structure of species found in these areas. Past studies have suggested that sky islands tend to have genetically structured populations, possibly due to reduced gene flow between montane areas. To test this hypothesis, we adopted the comparative approach. Using Amplified Fragment Length Polymorphisms, we compared population genetic structures of two closely related, similar sized butterfly species: Heteropsis oculus, a high elevation shola-grassland specialist restricted to the southern Western Ghats, and Mycalesis patnia, found more continuously distributed in lower elevations. In all analyses, as per expectation the sky island specialist H. oculus exhibited a greater degree of population genetic structure than M. patnia, implying a difference in geneflow. This difference in geneflow in turn appears to be due to the natural fragmentation of the sky island complexes. Detailed analysis of a subset of H. oculus samples from one sky island complex (the Anamalais) showed a surprising genetic break. A possible reason for this break could be unsuitable conditions of higher temperature and lower rainfall in the intervening valley region. Thus, sky island species are not only restricted by lack of habitat continuity between montane areas, but also by the nature of the intervening habitat.

CHEMICAL EVOLUTION OF RED MSX SOURCES IN THE SOUTHERN SKY

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

Yu, Naiping; Xu, Jinlong

Red Midcourse Space Experiment ( MSX ) Sources (RMSs) are regarded as excellent candidates of massive star-forming regions. In order to characterize the chemical properties of massive star formation, we made a systematic study of 87 RMSs in the southern sky, using archival data taken from the Atacama Pathfinder Experiment Telescope Large Area Survey of the Galaxy (ATLASGAL), the Australia Telescope Compact Array, and the Millimetre Astronomy Legacy Team Survey at 90 GHz (MALT90). According to previous multiwavelength observations, our sample could be divided into two groups: massive young stellar objects and H ii regions. Combined with the MALT90 data,more » we calculated the column densities of N{sub 2}H{sup +}, C{sub 2}H, HC{sub 3}N, and HNC and found that they are not much different from previous studies made in other massive star-forming regions. However, their abundances are relatively low compared to infrared dark clouds (IRDCs). The abundances of N{sub 2}H{sup +} and HNC in our sample are at least 1 mag lower than those found in IRDCs, indicating chemical depletions in the relatively hot gas. Besides, the fractional abundances of N{sub 2}H{sup +}, C{sub 2}H, and HC{sub 3}N seem to decrease as a function of their Lyman continuum fluxes (N {sub L}), indicating that these molecules could be destroyed by UV photons when H ii regions have formed inside. We also find that the C{sub 2}H abundance decreases faster than HC{sub 3}N with respect to N{sub L}. The abundance of HNC has a tight correlation with that of N{sub 2}H{sup +}, indicating that it may be also preferentially formed in cold gas. We regard our RMSs as being in a relatively late evolutionary stage of massive star formation.« less

Chemical Evolution of Red MSX Sources in the Southern Sky

NASA Astrophysics Data System (ADS)

Yu, Naiping; Xu, Jinlong

2016-12-01

Red Midcourse Space Experiment (MSX) Sources (RMSs) are regarded as excellent candidates of massive star-forming regions. In order to characterize the chemical properties of massive star formation, we made a systematic study of 87 RMSs in the southern sky, using archival data taken from the Atacama Pathfinder Experiment Telescope Large Area Survey of the Galaxy (ATLASGAL), the Australia Telescope Compact Array, and the Millimetre Astronomy Legacy Team Survey at 90 GHz (MALT90). According to previous multiwavelength observations, our sample could be divided into two groups: massive young stellar objects and H II regions. Combined with the MALT90 data, we calculated the column densities of N2H+, C2H, HC3N, and HNC and found that they are not much different from previous studies made in other massive star-forming regions. However, their abundances are relatively low compared to infrared dark clouds (IRDCs). The abundances of N2H+ and HNC in our sample are at least 1 mag lower than those found in IRDCs, indicating chemical depletions in the relatively hot gas. Besides, the fractional abundances of N2H+, C2H, and HC3N seem to decrease as a function of their Lyman continuum fluxes (N L ), indicating that these molecules could be destroyed by UV photons when H II regions have formed inside. We also find that the C2H abundance decreases faster than HC3N with respect to N L . The abundance of HNC has a tight correlation with that of N2H+, indicating that it may be also preferentially formed in cold gas. We regard our RMSs as being in a relatively late evolutionary stage of massive star formation.

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.

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.

Deepest Wide-Field Colour Image in the Southern Sky

NASA Astrophysics Data System (ADS)

2003-01-01

LA SILLA CAMERA OBSERVES CHANDRA DEEP FIELD SOUTH ESO PR Photo 02a/03 ESO PR Photo 02a/03 [Preview - JPEG: 400 x 437 pix - 95k] [Normal - JPEG: 800 x 873 pix - 904k] [HiRes - JPEG: 4000 x 4366 pix - 23.1M] Caption : PR Photo 02a/03 shows a three-colour composite image of the Chandra Deep Field South (CDF-S) , obtained with the Wide Field Imager (WFI) camera on the 2.2-m MPG/ESO telescope at the ESO La Silla Observatory (Chile). It was produced by the combination of about 450 images with a total exposure time of nearly 50 hours. The field measures 36 x 34 arcmin 2 ; North is up and East is left. Technical information is available below. The combined efforts of three European teams of astronomers, targeting the same sky field in the southern constellation Fornax (The Oven) have enabled them to construct a very deep, true-colour image - opening an exceptionally clear view towards the distant universe . The image ( PR Photo 02a/03 ) covers an area somewhat larger than the full moon. It displays more than 100,000 galaxies, several thousand stars and hundreds of quasars. It is based on images with a total exposure time of nearly 50 hours, collected under good observing conditions with the Wide Field Imager (WFI) on the MPG/ESO 2.2m telescope at the ESO La Silla Observatory (Chile) - many of them extracted from the ESO Science Data Archive . The position of this southern sky field was chosen by Riccardo Giacconi (Nobel Laureate in Physics 2002) at a time when he was Director General of ESO, together with Piero Rosati (ESO). It was selected as a sky region towards which the NASA Chandra X-ray satellite observatory , launched in July 1999, would be pointed while carrying out a very long exposure (lasting a total of 1 million seconds, or 278 hours) in order to detect the faintest possible X-ray sources. The field is now known as the Chandra Deep Field South (CDF-S) . The new WFI photo of CDF-S does not reach quite as deep as the available images of the "Hubble Deep Fields

Islands in the Sky: Ecophysiological Cloud-Vegetation Linkages in Southern Appalachian Mountain Cloud Forests

NASA Astrophysics Data System (ADS)

Reinhardt, K.; Emanuel, R. E.; Johnson, D. M.

2013-12-01

Mountain cloud forest (MCF) ecosystems are characterized by a high frequency of cloud fog, with vegetation enshrouded in fog. The altitudinal boundaries of cloud-fog zones co-occur with conspicuous, sharp vegetation ecotones between MCF- and non-MCF-vegetation. This suggests linkages between cloud-fog and vegetation physiology and ecosystem functioning. However, very few studies have provided a mechanistic explanation for the sharp changes in vegetation communities, or how (if) cloud-fog and vegetation are linked. We investigated ecophysiological linkages between clouds and trees in Southern Appalachian spruce-fir MCF. These refugial forests occur in only six mountain-top, sky-island populations, and are immersed in clouds on up to 80% of all growing season days. Our fundamental research questions was: How are cloud-fog and cloud-forest trees linked? We measured microclimate and physiology of canopy tree species across a range of sky conditions (cloud immersed, partly cloudy, sunny). Measurements included: 1) sunlight intensity and spectral quality; 2) carbon gain and photosynthetic capacity at leaf (gas exchange) and ecosystem (eddy covariance) scales; and 3) relative limitations to carbon gain (biochemical, stomatal, hydraulic). RESULTS: 1) Midday sunlight intensity ranged from very dark (<30 μmol m-2 s-1, under cloud-immersed conditions) to very bright (>2500 μmol m-2 s-1), and was highly variable on minute-to-minute timescales whenever clouds were present in the sky. Clouds and cloud-fog increased the proportion of blue-light wavelengths 5-15% compared to sunny conditions, and altered blue:red and red:far red ratios, both of which have been shown to strongly affect stomatal functioning. 2) Cloud-fog resulted in ~50% decreased carbon gain at leaf and ecosystem scales, due to sunlight levels below photosynthetic light-saturation-points. However, greenhouse studies and light-response-curve analyses demonstrated that MCF tree species have low light

Google Sky: A Digital View of the Night Sky

NASA Astrophysics Data System (ADS)

Connolly, A. Scranton, R.; Ornduff, T.

2008-11-01

From its inception Astronomy has been a visual science, from careful observations of the sky using the naked eye, to the use of telescopes and photographs to map the distribution of stars and galaxies, to the current era of digital cameras that can image the sky over many decades of the electromagnetic spectrum. Sky in Google Earth (http://earth.google.com) and Google Sky (http://www.google.com/sky) continue this tradition, providing an intuitive visual interface to some of the largest astronomical imaging surveys of the sky. Streaming multi-color imagery, catalogs, time domain data, as well as annotating interesting astronomical sources and events with placemarks, podcasts and videos, Sky provides a panchromatic view of the universe accessible to anyone with a computer. Beyond a simple exploration of the sky Google Sky enables users to create and share content with others around the world. With an open interface available on Linux, Mac OS X and Windows, and translations of the content into over 20 different languages we present Sky as the embodiment of a virtual telescope for discovery and sharing the excitement of astronomy and science as a whole.

The GMRT High Resolution Southern Sky Survey for Pulsars and Transients. I. Survey Description and Initial Discoveries

NASA Astrophysics Data System (ADS)

Bhattacharyya, B.; Cooper, S.; Malenta, M.; Roy, J.; Chengalur, J.; Keith, M.; Kudale, S.; McLaughlin, M.; Ransom, S. M.; Ray, P. S.; Stappers, B. W.

2016-02-01

We are conducting a survey for pulsars and transients using the Giant Metrewave Radio Telescope (GMRT). The GMRT High Resolution Southern Sky (GHRSS) survey is an off-Galactic plane (| b| > 5) survey in the declination range -40° to -54° at 322 MHz. With the high time (up to 30.72 μs) and frequency (up to 0.016275 MHz) resolution observing modes, the 5σ detection limit is 0.5 mJy for a 2 ms pulsar with a 10% duty cycle at 322 MHz. The total GHRSS sky coverage of 2866 deg2 will result from 1953 pointings, each covering 1.8 deg2. The 10σ detection limit for a 5 ms transient burst is 1.6 Jy for the GHRSS survey. In addition, the GHRSS survey can reveal transient events like rotating radio transients or fast radio bursts. With 35% of the survey completed (I.e., 1000 deg2), we report the discovery of 10 pulsars, 1 of which is a millisecond pulsar (MSP), which is among the highest pulsar per square degree discovery rates for any off-Galactic plane survey. We re-detected 23 known in-beam pulsars. Utilizing the imaging capability of the GMRT, we also localized four of the GHRSS pulsars (including the MSP) in the gated image plane within ±10″. We demonstrated rapid convergence in pulsar timing with a more precise position than is possible with single-dish discoveries. We also show that we can localize the brightest transient sources with simultaneously obtained lower time resolution imaging data, demonstrating a technique that may have application in the Square Kilometre Array.

HIGH-VELOCITY CLOUDS IN THE GALACTIC ALL SKY SURVEY. I. CATALOG

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

Moss, V. A.; Kummerfeld, J. K.; McClure-Griffiths, N. M.

2013-11-01

We present a catalog of high-velocity clouds (HVCs) from the Galactic All Sky Survey (GASS) of southern sky neutral hydrogen, which has 57 mK sensitivity and 1 km s{sup –1} velocity resolution and was obtained with the Parkes Telescope. Our catalog has been derived from the stray-radiation-corrected second release of GASS. We describe the data and our method of identifying HVCs and analyze the overall properties of the GASS population. We catalog a total of 1693 HVCs at declinations <0°, including 1111 positive velocity HVCs and 582 negative velocity HVCs. Our catalog also includes 295 anomalous velocity clouds (AVCs). Themore » cloud line-widths of our HVC population have a median FWHM of ∼19 km s{sup –1}, which is lower than that found in previous surveys. The completeness of our catalog is above 95% based on comparison with the HIPASS catalog of HVCs upon which we improve by an order of magnitude in spectral resolution. We find 758 new HVCs and AVCs with no HIPASS counterpart. The GASS catalog will shed unprecedented light on the distribution and kinematic structure of southern sky HVCs, as well as delve further into the cloud populations that make up the anomalous velocity gas of the Milky Way.« 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).

RELEVANT ASPECTS OF MEDIUM-SCALE TIDs RELATED WITH MIDLATITUDES SPREAD- F OBSERVED BY ALL-SKY IMAGING SYSTEM IN THE SOUTHERN HEMISPHERE OVER TWO FULL SOLAR CYCLES

NASA Astrophysics Data System (ADS)

Pimenta, A. A.

2009-12-01

Using ground-based measurements we investigate the occurrence of medium-scale TIDs (MSTIDs) in the OI 630 nm nightglow emission all-sky images in the Brazilian low latitudes region related with midlatitude Spread F, during over two full solar cycles. The OI 630 nm images obtained during these periods show thermospheric dark band structures (MSTIDs) in low latitudes region propagating from southeast to northwest. These dark patches moved with average speed of about 50-200 m/s. Only during low solar activity period (LSA), ascending solar activity period (ASA) and descending solar activity period the DBS occurrences were observed in the OI630 nm nightglow emission all-sky images. However, during high solar activity (HAS) we didn’t observe the DBS in the all-sky images. In addition, ionospheric data over two stations in Brazil, one at the magnetic equator (São Luís) and the other close to the southern crest of the equatorial ionization anomaly (Cachoeira Paulista) were used to study this kind of structures during high and low solar activity periods. It should be pointed out that these thermospheric/ionospheric events are not related to geomagnetic disturbed conditions. In this work, we present and discuss this phenomenon in the Brazilian sector over two full solar cycles under different solar activity conditions. A possible mechanism for generation of these dark band structures is presented.

Man-made Star Shines in the Southern Sky

NASA Astrophysics Data System (ADS)

2006-02-01

Scientists celebrate another major milestone at Cerro Paranal in Chile, home of ESO's Very Large Telescope array. Thanks to their dedicated efforts, they were able to create the first artificial star in the Southern Hemisphere, allowing astronomers to study the Universe in the finest detail. This artificial laser guide star makes it possible to apply adaptive optics systems, that counteract the blurring effect of the atmosphere, almost anywhere in the sky. ESO PR Photo 07a/06 ESO PR Photo 07a/06 First Light of the VLT Laser Guide Star On 28 January 2006, at 23:07 local time, a laser beam of several watts was launched from Yepun, the fourth 8.2m Unit Telescope of the Very Large Telescope, producing an artificial star, 90 km up in the atmosphere. Despite this star being about 20 times fainter than the faintest star that can be seen with the unaided eye, it is bright enough for the adaptive optics to measure and correct the atmosphere's blurring effect. The event was greeted with much enthusiasm and happiness by the people in the control room of one of the most advanced astronomical facilities in the world. It was the culmination of five years of collaborative work by a team of scientists and engineers from ESO and the Max Planck Institutes for Extraterrestrial Physics in Garching and for Astronomy in Heidelberg, Germany. After more than one month of integration on site with the invaluable support of the Paranal Observatory staff, the VLT Laser Guide Star Facility saw First Light and propagated into the sky a 50cm wide, vivid, beautifully yellow beam. ESO PR Photo 07b/06 ESO PR Photo 07b/06 An Artificial Star Above Paranal "This event tonight marks the beginning of the Laser Guide Star Adaptive Optics era for ESO's present and future telescopes", said Domenico Bonaccini Calia, Head of the Laser Guide Star group at ESO and LGSF Project Manager. Normally, the achievable image sharpness of a ground-based telescope is limited by the effect of atmospheric turbulence. This

yourSky: Custom Sky-Image Mosaics via the Internet

NASA Technical Reports Server (NTRS)

Jacob, Joseph

2003-01-01

yourSky (http://yourSky.jpl.nasa.gov) is a computer program that supplies custom astronomical image mosaics of sky regions specified by requesters using client computers connected to the Internet. [yourSky is an upgraded version of the software reported in Software for Generating Mosaics of Astronomical Images (NPO-21121), NASA Tech Briefs, Vol. 25, No. 4 (April 2001), page 16a.] A requester no longer has to engage in the tedious process of determining what subset of images is needed, nor even to know how the images are indexed in image archives. Instead, in response to a requester s specification of the size and location of the sky area, (and optionally of the desired set and type of data, resolution, coordinate system, projection, and image format), yourSky automatically retrieves the component image data from archives totaling tens of terabytes stored on computer tape and disk drives at multiple sites and assembles the component images into a mosaic image by use of a high-performance parallel code. yourSky runs on the server computer where the mosaics are assembled. Because yourSky includes a Web-interface component, no special client software is needed: ordinary Web browser software is sufficient.

GT-10 - EARTH SKY - SOUTHERN HALF OF FORMOSA

NASA Image and Video Library

1966-08-01

S66-45868 (18-21 July 1966) --- Southern half of the island of Taiwan (Formosa) as seen from the Gemini-10 spacecraft. Taken with a J.A. Maurer 70mm camera, using Eastman Kodak, Ektachrome, MS (S.O. 217) color film. Photo credit: NASA

Gamma-sky.net: Portal to the gamma-ray sky

NASA Astrophysics Data System (ADS)

Voruganti, Arjun; Deil, Christoph; Donath, Axel; King, Johannes

2017-01-01

http://gamma-sky.net is a novel interactive website designed for exploring the gamma-ray sky. The Map View portion of the site is powered by the Aladin Lite sky atlas, providing a scalable survey image tesselated onto a three-dimensional sphere. The map allows for interactive pan and zoom navigation as well as search queries by sky position or object name. The default image overlay shows the gamma-ray sky observed by the Fermi-LAT gamma-ray space telescope. Other survey images (e.g. Planck microwave images in low/high frequency bands, ROSAT X-ray image) are available for comparison with the gamma-ray data. Sources from major gamma-ray source catalogs of interest (Fermi-LAT 2FHL, 3FGL and a TeV source catalog) are overlaid over the sky map as markers. Clicking on a given source shows basic information in a popup, and detailed pages for every source are available via the Catalog View component of the website, including information such as source classification, spectrum and light-curve plots, and literature references. We intend for gamma-sky.net to be applicable for both professional astronomers as well as the general public. The website started in early June 2016 and is being developed as an open-source, open data project on GitHub (https://github.com/gammapy/gamma-sky). We plan to extend it to display more gamma-ray and multi-wavelength data. Feedback and contributions are very welcome!

Digital all-sky polarization imaging of partly cloudy skies.

PubMed

Pust, Nathan J; Shaw, Joseph A

2008-12-01

Clouds reduce the degree of linear polarization (DOLP) of skylight relative to that of a clear sky. Even thin subvisual clouds in the "twilight zone" between clouds and aerosols produce a drop in skylight DOLP long before clouds become visible in the sky. In contrast, the angle of polarization (AOP) of light scattered by a cloud in a partly cloudy sky remains the same as in the clear sky for most cases. In unique instances, though, select clouds display AOP signatures that are oriented 90 degrees from the clear-sky AOP. For these clouds, scattered light oriented parallel to the scattering plane dominates the perpendicularly polarized Rayleigh-scattered light between the instrument and the cloud. For liquid clouds, this effect may assist cloud particle size identification because it occurs only over a relatively limited range of particle radii that will scatter parallel polarized light. Images are shown from a digital all-sky-polarization imager to illustrate these effects. Images are also shown that provide validation of previously published theories for weak (approximately 2%) polarization parallel to the scattering plane for a 22 degrees halo.

A partial list of southern clusters of galaxies

NASA Technical Reports Server (NTRS)

Quintana, H.; White, R. A.

1990-01-01

An inspection of 34 SRC/ESO J southern sky fields is the basis of the present list of clusters of galaxies and their approximate classifications in terms of cluster concentration, defined independently of richness and shape-symmetry. Where possible, an estimate of the cluster morphological population is provided. The Bautz-Morgan classification was applied using a strict comparison with clusters on the Palomar Sky Survey. Magnitudes were estimated on the basis of galaxies with photoelectric or photographic magnitudes.

Four faint T dwarfs from the UKIRT Infrared Deep Sky Survey (UKIDSS) Southern Stripe

NASA Astrophysics Data System (ADS)

Chiu, Kuenley; Liu, Michael C.; Jiang, Linhua; Allers, Katelyn N.; Stark, Daniel P.; Bunker, Andrew; Fan, Xiaohui; Glazebrook, Karl; Dupuy, Trent J.

2008-03-01

We present the optical and near-infrared photometry and spectroscopy of four faint T dwarfs newly discovered from the UKIDSS first data release. The sample, drawn from an imaged area of ~136 deg2 to a depth of Y = 19.9 (5σ, Vega), is located in the Sloan Digital Sky Survey (SDSS) Southern Equatorial Stripe, a region of significant future deep imaging potential. We detail the selection and followup of these objects, three of which are spectroscopically confirmed brown dwarfs ranging from type T2.5 to T7.5, and one is photometrically identified as early T. Their magnitudes range from Y = 19.01 to 19.88 with derived distances from 34 to 98 pc, making these among the coldest and faintest brown dwarfs known. The T7.5 dwarf appears to be single based on 0.05-arcsec images from Keck laser guide star adaptive optics. The sample brings the total number of T dwarfs found or confirmed by UKIDSS data in this region to nine, and we discuss the projected numbers of dwarfs in the future survey data. We estimate that ~240 early and late T dwarfs are discoverable in the UKIDSS Large Area Survey (LAS) data, falling significantly short of published model projections and suggesting that initial mass functions and/or birth rates may be at the low end of possible models. Thus, deeper optical data have good potential to exploit the UKIDSS survey depth more fully, but may still find the potential Y dwarf sample to be extremely rare.

Physiological, anatomical, and ecological characteristics of southern live oak

Treesearch

Yadong Qi; Jammie Favorite; Kit L. Chin; Ying Xiao

2006-01-01

Gas exchanges of sun-exposed and shaded leaves of southern live oak (Quercus virginiana Mill.) were studied monthly from May to September, 2000. Six healthy live oak trees with d.b.h. ranging from 21 to 148 cm on Southern University’s campus in Baton Rouge, LA, were selected for the study. Instantaneous gas exchanges were measured during clear sky...

Dark Sky Protection and Education - Izera Dark Sky Park

NASA Astrophysics Data System (ADS)

Berlicki, Arkadiusz; Kolomanski, Sylwester; Mrozek, Tomasz; Zakowicz, Grzegorz

2015-08-01

Darkness of the night sky is a natural component of our environment and should be protected against negative effects of human activities. The night darkness is necessary for balanced life of plants, animals and people. Unfortunately, development of human civilization and technology has led to the substantial increase of the night-sky brightness and to situation where nights are no more dark in many areas of the World. This phenomenon is called "light pollution" and it can be rank among such problems as chemical pollution of air, water and soil. Besides the environment, the light pollution can also affect e.g. the scientific activities of astronomers - many observatories built in the past began to be located within the glow of city lights making the night observations difficult, or even impossible.In order to protect the natural darkness of nights many so-called "dark sky parks" were established, where the darkness is preserved, similar to typical nature reserves. The role of these parks is not only conservation but also education, supporting to make society aware of how serious the problem of the light pollution is.History of the dark sky areas in Europe began on November 4, 2009 in Jizerka - a small village situated in the Izera Mountains, when Izera Dark Sky Park (IDSP) was established - it was the first transboundary dark sky park in the World. The idea of establishing that dark sky park in the Izera Mountains originated from a need to give to the society in Poland and Czech Republic the knowledge about the light pollution. Izera Dark Sky Park is a part of the astro-tourism project "Astro Izery" that combines tourist attraction of Izera Valley and astronomical education under the wonderful starry Izera sky. Besides the IDSP, the project Astro Izery consists of the set of simple astronomical instruments (gnomon, sundial), natural educational trail "Solar System Model", and astronomical events for the public. In addition, twice a year we organize a 3-4 days

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/.

A large-format imager for the SkyMapper Survey Telescope

NASA Astrophysics Data System (ADS)

Granlund, A.; Conroy, P. G.; Keller, S. C.; Oates, A. P.; Schmidt, B.; Waterson, M. F.; Kowald, E.; Dawson, M. I.

2006-06-01

The Research School of Astronomy and Astrophysics (RSAA) of the Australian National University (ANU) at Mt Stromlo Observatory is developing a wide-field Cassegrain Imager for the new 1.3m SkyMapper Survey Telescope under construction for Siding Spring Observatory, NSW, Australia. The Imager features a fast-readout, low-noise 268 Million pixel CCD mosaic that provides a 5.7 square degree field of view. Given the close relative sizes of the telescope and Imager, the work is proceeding in close collaboration with the telescope's manufacturer, Electro Optics Systems Pty Ltd (Canberra, Australia). The design of the SkyMapper Imager focal plane is based on E2V (Chelmsford, UK) deep depletion CCDs. These devices have 2048 x 4096 15 micron pixels, and provide a 91% filling factor in our mosaic configuration of 4 x 8 chips. In addition, the devices have excellent quantum efficiency from 300nm-950nm, near perfect cosmetics, and low-read noise, making them well suited to the all-sky ultraviolet through near-IR Southern Sky Survey to be conducted by the telescope. The array will be controlled using modified versions of the new IOTA controllers being developed for Pan-STARRS by Onaka and Tonry et al. These controllers provide a cost effective, low-volume, high speed solution for our detector read-out requirements. The system will have an integrated 6-filter exchanger, and Shack-Hartmann optics, and will be cooled by closed-cycle helium coolers. This paper will present the specifications, and opto-mechanical and detector control design of the SkyMapper Imager, including the test results of the detector characterisation and manufacturing progress.

The interactive sky: a browsable allsky image

NASA Astrophysics Data System (ADS)

Tancredi, Gonzalo; Da Rosa, Fernando; Roland, Santiago; Almenares, Luciano; Gomez, Fernando

2015-08-01

We are conducting a project to make available panoramas of the night sky of the southern hemisphere, based on a mosaic of hundred of photographs. Each allsky panorama is a giant image composed by hundreds of high-resolution photos taken in the course of one night. The panoramas are accessible with a web-browser and the public is able to zoom on them and to see the sky with better quality than the naked eye. We are preparing 4 sets of panoramas corresponding to the four seasons.The individual images are taken with a 16 Mpixels DLSR camera with a 50 mm lens mounted on a Gigapan EPIC robotic camera mounts. These devices and a autoguiding telescope are mounted in a equatorial telescope mount, which allows us to have exposure of several tens seconds. The images are then processed and stitched to create the gigantic panorama, with typical weight of several GBytes.The limiting magnitude is V~8. The panoramas include more than 50 times more stars those detected with the naked eye.In addition to the allsky panoramas, we embedded higher resolution images of specific regions of interest such as: emission nebulae and dark, open and globular clusters and galaxies; which can be zoomed.The photographs have been acquiring since December 2014 in a dark place with low light pollution in the countryside of Uruguay; which allows us to achieve deep sky objects.These panoramas will be available on a website and can be accessed with any browser.This tool will be available for teaching purposes, astronomy popularization or introductory research. Teacher guides will be developed for educational activities at different educational levels.While there are similar projects like Google Sky, the methodology used to generate the giant panoramas allows a much more realistic view, with a background of continuous sky without sharp edges. Furthermore, while the planetarium software is based on drawings of the stars, our panoramas are based on real images.This is the first project with these

Ancient geographical gaps and paleo-climate shape the phylogeography of an endemic bird in the sky islands of southern India.

PubMed

Robin, V V; Sinha, Anindya; Ramakrishnan, Uma

2010-10-13

Sky islands, formed by the highest reaches of mountain tracts physically isolated from one another, represent one of the biodiversity-rich regions of the world. Comparative studies of geographically isolated populations on such islands can provide valuable insights into the biogeography and evolution of species on these islands. The Western Ghats mountains of southern India form a sky island system, where the relationship between the island structure and the evolution of its species remains virtually unknown despite a few population genetic studies. We investigated how ancient geographic gaps and glacial cycles have partitioned genetic variation in modern populations of a threatened endemic bird, the White-bellied Shortwing Brachypteryx major, across the montane Shola forests on these islands and also inferred its evolutionary history. We used bayesian and maximum likelihood-based phylogenetic and population-genetic analyses on data from three mitochondrial markers and one nuclear marker (totally 2594 bp) obtained from 33 White-bellied Shortwing individuals across five islands. Genetic differentiation between populations of the species correlated with the locations of deep valleys in the Western Ghats but not with geographical distance between these populations. All populations revealed demographic histories consistent with population founding and expansion during the Last Glacial Maximum. Given the level of genetic differentiation north and south of the Palghat Gap, we suggest that these populations be considered two different taxonomic species. Our results show that the physiography and paleo-climate of this region historically resulted in multiple glacial refugia that may have subsequently driven the evolutionary history and current population structure of this bird. The first avian genetic study from this biodiversity hotspot, our results provide insights into processes that may have impacted the speciation and evolution of the endemic fauna of this region.

The Southern HII Region Discovery Survey: The Bright Catalog

NASA Astrophysics Data System (ADS)

Wenger, Trey V.; Dickey, John M.; Jordan, Christopher H.; Balser, Dana; Armentrout, William Paul; Anderson, Loren; Bania, Thomas; Dawson, Joanne; McClure-Griffiths, Naomi M.; Shea, Jeanine

2018-01-01

HII regions, the zones of ionized gas surrounding recently formed high-mass stars, are the archetypical tracers of Galactic structure. The census of Galactic HII regions in the Southern sky is vastly incomplete due to a lack of sensitive radio recombination line (RRL) surveys. The Southern HII Region Discovery Survey (SHRDS) is a 900-hour Australia Telescope Compact Array cm-wavelength RRL and continuum emission survey of hundreds of third and fourth quadrant Galactic HII region candidates. These candidates are identified in the Widefield Infrared Survey Explorer (WISE) Catalog of Galactic HII Regions based on coincident 10 micron (WISE) and 20 cm (Southern Galactic Plane Survey) emission. The SHRDS is an extension of HII Region Discovery Surveys in the Northern sky with the Green Bank Telescope and Arecibo Telescope which discovered ~800 new HII regions. In the first 500 hours of the SHRDS, we targeted the 249 brightest HII region candidates and 33 previously known HII regions. We discuss the data reduction, analysis, and preliminary results from this first stage of the survey.

For Spacious Skies Activity Guide. An Interdisciplinary Approach to the Sky.

ERIC Educational Resources Information Center

Ward, C. Whitney; Borden, Jack

Despite the fact that the sky is the most dominant feature of our surroundings, it plays the role of an unseen background for may objects. It is the intent of this guide to bring about an awareness of the sky to young people. Topics for activities include: (1) "Sky Awareness"; (2) "Compass"; (3) "Hand Lens"; (4) "Prism"; (5) "Binoculars"; (6)…

PePSS - A portable sky scanner for measuring extremely low night-sky brightness

NASA Astrophysics Data System (ADS)

Kocifaj, Miroslav; Kómar, Ladislav; Kundracik, František

2018-05-01

A new portable sky scanner designed for low-light-level detection at night is developed and employed in night sky brightness measurements in a rural region. The fast readout, adjustable sensitivity and linear response guaranteed in 5-6 orders of magnitude makes the device well suited for narrow-band photometry in both dark areas and bright urban and suburban environments. Quasi-monochromatic night-sky brightness data are advantageous in the accurate characterization of spectral power distribution of scattered and emitted light and, also allows for the possibility to retrieve light output patterns from whole-city light sources. The sky scanner can operate in both night and day regimes, taking advantage of the complementarity of both radiance data types. Due to its inherent very high sensitivity the photomultiplier tube could be used in night sky radiometry, while the spectrometer-equipped system component capable of detecting elevated intensities is used in daylight monitoring. Daylight is a source of information on atmospheric optical properties that in turn are necessary in processing night sky radiances. We believe that the sky scanner has the potential to revolutionize night-sky monitoring systems.

Bernhard Schmidt and the Schmidt Telescope for Mapping the Sky

NASA Astrophysics Data System (ADS)

Wolfschmidt, G.

Bernhard Voldemar Schmidt (1879--1935) was born in Estonia. He ran an optical workshop in Mittweida, Saxonia, between 1901 and 1927. Astronomers appreciated the quality of his telescopes. Starting in 1925, working freelance in Hamburg Observatory, he developed a short focal length optical system with a large field of view. He succeeded in inventing the ``Schmidt Telescope'' in 1930, which allows the imaging a large field of the sky without any distortions. Shortly after Schmidt's death, the director of the observatory published details on the invention and production of the Schmidt Telescope. After World War II, Schmidt telescopes have been widely used. The first large Schmidt telescope was built in 1948, the ``Big Schmidt'' (126 cm), Mount Palomar, USA. Schmidt telescopes are also important tools for cosmology. The result of the Palomar Observatory Sky Surveys (1949--1958, 1985--1999) is a data base of about 20 million galaxies and over 100 million stars, supplemented in 1971 by the ESO Schmidt for the southern sky. Also high resolution spectrometers can be fitted to the Schmidt telescope. The 80 cm Schmidt telescope of Hamburg Observatory, planned since 1936, finished 1955, is on Calar Alto, Spain, since 1975. Combined with two objective prisms, it was used for a Quasar survey project.

Sky Detection in Hazy Image.

PubMed

Song, Yingchao; Luo, Haibo; Ma, Junkai; Hui, Bin; Chang, Zheng

2018-04-01

Sky detection plays an essential role in various computer vision applications. Most existing sky detection approaches, being trained on ideal dataset, may lose efficacy when facing unfavorable conditions like the effects of weather and lighting conditions. In this paper, a novel algorithm for sky detection in hazy images is proposed from the perspective of probing the density of haze. We address the problem by an image segmentation and a region-level classification. To characterize the sky of hazy scenes, we unprecedentedly introduce several haze-relevant features that reflect the perceptual hazy density and the scene depth. Based on these features, the sky is separated by two imbalance SVM classifiers and a similarity measurement. Moreover, a sky dataset (named HazySky) with 500 annotated hazy images is built for model training and performance evaluation. To evaluate the performance of our method, we conducted extensive experiments both on our HazySky dataset and the SkyFinder dataset. The results demonstrate that our method performs better on the detection accuracy than previous methods, not only under hazy scenes, but also under other weather conditions.

Sky Detection in Hazy Image

PubMed Central

Song, Yingchao; Luo, Haibo; Ma, Junkai; Hui, Bin; Chang, Zheng

2018-01-01

Sky detection plays an essential role in various computer vision applications. Most existing sky detection approaches, being trained on ideal dataset, may lose efficacy when facing unfavorable conditions like the effects of weather and lighting conditions. In this paper, a novel algorithm for sky detection in hazy images is proposed from the perspective of probing the density of haze. We address the problem by an image segmentation and a region-level classification. To characterize the sky of hazy scenes, we unprecedentedly introduce several haze-relevant features that reflect the perceptual hazy density and the scene depth. Based on these features, the sky is separated by two imbalance SVM classifiers and a similarity measurement. Moreover, a sky dataset (named HazySky) with 500 annotated hazy images is built for model training and performance evaluation. To evaluate the performance of our method, we conducted extensive experiments both on our HazySky dataset and the SkyFinder dataset. The results demonstrate that our method performs better on the detection accuracy than previous methods, not only under hazy scenes, but also under other weather conditions. PMID:29614778

Early German plans for southern observatories

NASA Astrophysics Data System (ADS)

Wolfschmidt, G.

2002-07-01

As early as the 18th and 19th centuries, French and English observers were active in South Africa. Around the beginning of the 20th century, Heidelberg and Potsdam astronomers proposed a southern observatory. Then Göttingen astronomers suggested building an observatory in Windhoek for photographing the sky and measuring the solar constant. In 1910 Karl Schwarzschild (1873-1916), after a visit to observatories in the United States, pointed out the usefulness of an observatory in South West Africa, in a climate superior to that in Germany, giving German astronomers access to the southern sky. Seeing tests were begun in 1910 by Potsdam astronomers, but WW I stopped the plans. In 1928 Erwin Finlay-Freundlich (1885-1964), inspired by the Hamburg astronomer Walter Baade (1893-1960), worked out a detailed plan for a southern observatory with a reflecting telescope, spectrographs and an astrograph with an objective prism. Paul Guthnick (1879-1947), director of the Berlin observatory, in cooperation with APO Potsdam and Hamburg, made a site survey to Africa in 1929 and found the conditions in Windhoek to be ideal. Observations were started in the 1930s by Berlin and Breslau astronomers, but were stopped by WW II. In the 1950s, astronomers from Hamburg and The Netherlands renewed the discussion in the framework of European cooperation, and this led to the founding of ESO in 1963.

For Spacious Skies: A Teacher's Guide. An Interdisciplinary Approach to the Sky.

ERIC Educational Resources Information Center

For Spacious Skies, Inc., Lexington, MA.

Despite the fact that the sky is the most dominant feature of our surroundings, it plays the role of an unseen background for many objects. It is the intent of this guide to bring about an awareness of the sky to young people. Topics for activities include: (1) "Sky Awareness"; (2) "Compass"; (3) "Hand Lens"; (4)…

CFHT's SkyProbe: a real-time sky-transparency monitor

NASA Astrophysics Data System (ADS)

Cuillandre, Jean-Charles; Magnier, Eugene A.; Isani, Sidik; Sabin, Daniel; Knight, Wiley; Kras, Simon; Lai, Kamson

2002-12-01

We have developed a system at the Canada-France-Hawaii Telescope (CFHT), SkyProbe, which allows for the direct measurement of the true attenuation by clouds once per minute, within a percent, directly on the field pointed by the telescope. It has been possible to make this system relatively inexpensively due to the low-cost CCD cameras from the amateur market. A crucial addition to this hardware is the quite recent availability of a full-sky photometry catalog at the appropriate depth: the Tycho catalog, from the Hipparcos mission. The central element is the automatic data analysis pipeline developed at CFHT, Elixir, for the improved operation of the CFHT wide-field imagers, CFH12K and MegaCam. SkyProbe"s FITS images are processed in real-time and the pipeline output (a zero point attenuation) provides the current sky transmission to the observers and helps immediate decision making. These measurements are also attached to the archived data, adding a key criteria for future use by other astronomers.

STRUCTURE IN THE ROTATION MEASURE SKY

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

Stil, J. M.; Taylor, A. R.; Sunstrum, C.

2011-01-01

An analysis of structure in rotation measure (RM) across the sky based on the RM catalog of Taylor et al. is presented. Several resolved RM structures are identified with structure in the local interstellar medium, including radio loops I, II, and III, the Gum nebula, and the Orion-Eridanus superbubble. Structure functions (SFs) of RM are presented for selected areas, and maps of SF amplitude and slope across the sky are compared with H{alpha} intensity and diffuse polarized intensity. RM variance on an angular scale of 1{sup 0} is correlated with length of the line of sight through the Galaxy, withmore » a contribution from local structures. The slope of the SFs is less concentrated to the Galactic plane and less correlated with length of the line of sight through the Galaxy, suggesting a more local origin for RM structure on angular scales {approx}10{sup 0}. The RM variance is a factor of {approx}2 higher toward the South Galactic Pole than toward the North Galactic Pole, reflecting a more wide-spread asymmetry between the northern and southern Galactic hemispheres. Depolarization of diffuse Galactic synchrotron emission at latitudes <30{sup 0} can be explained largely by Faraday dispersion related to small-scale variance in RM, but the errors allow a significant contribution from differential Faraday rotation along the line of sight.« less

View of Comet Siding Spring from Southern Hemisphere Artist Concept

NASA Image and Video Library

2014-10-09

Comet Siding Spring will have a close approach to Mars on Oct. 19, 2014. This artist concept shows people in the Southern Hemisphere where to look for Mars in the night sky. Mars and the comet may be visible with binoculars.

Early star catalogues of the southern sky. De Houtman, Kepler (second and third classes), and Halley

NASA Astrophysics Data System (ADS)

Verbunt, F.; van Gent, R. H.

2011-06-01

De Houtman in 1603, Kepler in 1627 and Halley in 1679 published the earliest modern catalogues of the southern sky. We provide machine-readable versions of these catalogues, make some comparisons between them, and briefly discuss their accuracy on the basis of comparison with data from the modern Hipparcos Catalogue. We also compare our results for De Houtman with those by Knobel in 1917 finding good overall agreement. About half of the ~ 200 new stars (with respect to Ptolemaios) added by De Houtman are in twelve new constellations, half in old constellations like Centaurus, Lupus and Argo. The right ascensions and declinations given by De Houtman have error distributions with widths of about 40', the longitudes and latitudes given by Kepler have error distributions with widths of about 45'. Halley improves on this by more than an order of magnitude to widths of about 3', and all entries in his catalogue can be identified. The measurement errors of Halley are due to a systematic deviation of his sextant (increasing with angle to 2' at 60°) and random errors of 0.7 arcmin. The position errors in the catalogue of Halley are dominated by the position errors in the reference stars, which he took from Brahe. The full Tables Houtman, Classis, Aliter and Halley (see Tables 6, 7, 8) are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/530/A93

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.

Sky coverage modeling for the whole sky for laser guide star multiconjugate adaptive optics.

PubMed

Wang, Lianqi; Andersen, David; Ellerbroek, Brent

2012-06-01

The scientific productivity of laser guide star adaptive optics systems strongly depends on the sky coverage, which describes the probability of finding natural guide stars for the tip/tilt wavefront sensor(s) to achieve a certain performance. Knowledge of the sky coverage is also important for astronomers planning their observations. In this paper, we present an efficient method to compute the sky coverage for the laser guide star multiconjugate adaptive optics system, the Narrow Field Infrared Adaptive Optics System (NFIRAOS), being designed for the Thirty Meter Telescope project. We show that NFIRAOS can achieve more than 70% sky coverage over most of the accessible sky with the requirement of 191 nm total rms wavefront.

On-sky demonstration of matched filters for wavefront measurements using ELT-scale elongated laser guide stars

NASA Astrophysics Data System (ADS)

Basden, A. G.; Bardou, L.; Bonaccini Calia, D.; Buey, T.; Centrone, M.; Chemla, F.; Gach, J. L.; Gendron, E.; Gratadour, D.; Guidolin, I.; Jenkins, D. R.; Marchetti, E.; Morris, T. J.; Myers, R. M.; Osborn, J.; Reeves, A. P.; Reyes, M.; Rousset, G.; Lombardi, G.; Townson, M. J.; Vidal, F.

2017-04-01

The performance of adaptive optics systems is partially dependent on the algorithms used within the real-time control system to compute wavefront slope measurements. We demonstrate the use of a matched filter algorithm for the processing of elongated laser guide star (LGS) Shack-Hartmann images, using the CANARY adaptive optics instrument on the 4.2 m William Herschel Telescope and the European Southern Observatory Wendelstein LGS Unit placed 40 m away. This algorithm has been selected for use with the forthcoming Thirty Meter Telescope, but until now had not been demonstrated on-sky. From the results of a first observing run, we show that the use of matched filtering improves our adaptive optics system performance, with increases in on-sky H-band Strehl measured up to about a factor of 1.1 with respect to a conventional centre of gravity approach. We describe the algorithm used, and the methods that we implemented to enable on-sky demonstration.

SkyMapper Filter Set: Design and Fabrication of Large-Scale Optical Filters

NASA Astrophysics Data System (ADS)

Bessell, Michael; Bloxham, Gabe; Schmidt, Brian; Keller, Stefan; Tisserand, Patrick; Francis, Paul

2011-07-01

The SkyMapper Southern Sky Survey will be conducted from Siding Spring Observatory with u, v, g, r, i, and z filters that comprise glued glass combination filters with dimensions of 309 × 309 × 15 mm. In this article we discuss the rationale for our bandpasses and physical characteristics of the filter set. The u, v, g, and z filters are entirely glass filters, which provide highly uniform bandpasses across the complete filter aperture. The i filter uses glass with a short-wave pass coating, and the r filter is a complete dielectric filter. We describe the process by which the filters were constructed, including the processes used to obtain uniform dielectric coatings and optimized narrowband antireflection coatings, as well as the technique of gluing the large glass pieces together after coating using UV transparent epoxy cement. The measured passbands, including extinction and CCD QE, are presented.

Dark Skies are a Universal Resource. So are Quiet Skies!

NASA Astrophysics Data System (ADS)

Maddalena, Ronald J.; Heatherly, S.

2008-05-01

You've just purchased your first telescope. But where to set it up? Certainly not a WalMart parking lot. Too much light pollution! In the same way that man-made light obscures our night sky and blinds ground-based optical telescopes, man-made radio signals blind radio telescopes as well. NRAO developed the Quiet Skies project to increase awareness of radio frequency interference (RFI) and radio astronomy in general by engaging students in local studies of RFI. To do that we created a sensitive detector which measures RFI. We produced 20 of these, and assembled kits containing detectors and supplementary materials for loan to schools. Students conduct experiments to measure the properties of RFI in their area, and input their measurements into a web-based data base. The Quiet Skies project is a perfect complement to the IYA Dark Skies Awareness initiative. We hope to place 500 Quiet Skies detectors into the field through outreach to museums and schools around the world. Should we be successful, we will sustain this global initiative via a continuing loan program. One day we hope to have a publicly generated image of the Earth which shows RFI much as the Earth at Night image illustrates light pollution. The poster will present the components of the project in detail, including our plans for IYA, and various low-cost alternative strategies for introducing RFI and radio astronomy to the public. We will share the results of some of the experiments already being performed by high school students. Development of the Quiet Skies project was funded by a NASA IDEAS grant. The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.

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

The Sky This Week, 2016 April 26 - May 3 - Naval Oceanography Portal

Science.gov Websites

the week coursing through the summer Milky Way, skirting the southern reaches of the ecliptic in the morning sky. Last Quarter occurs on the 29th at 11:29 pm Eastern Daylight Time. As Luna wanes through her begins on the 29th and lasts through May 8th. This month's target constellation is Leo, the Lion, which

Explorers of the Southern Sky: A History of Australian Astronomy

NASA Astrophysics Data System (ADS)

Haynes, Raymond; Haynes, Roslynn D.; Malin, David; McGee, Richard

1996-06-01

This well-illustrated volume is the most comprehensive account of Australian astronomy to date. It is both an indispensable reference book on the history of astronomy in Australia, and a highly readable study of a scientific discipline in the context of emerging nationhood. It covers not only the science, but the individuals involved and the social and economic climate in which they worked. Starting from the ancient Aboriginal beliefs about the Sky World - the earliest known astronomy, anywhere in the world - we are led through to the most exciting high-tech current and projected research being carried out at Australia's world-class national astronomy facilities, and by groups in Australian universities. All branches of astronomy are covered - optical, infrared, X-ray, gamma-ray, microwave, gravitational wave and theoretical - including the contribution of amateur astronomers. The non-technical language, many illustrations, and explanatory figures, ensure that this guide will appeal to a wide range of readers - including professional astronomers, historians of science, students, amateur astronomers and general readers.

Early German Plans for a Southern Observatory

NASA Astrophysics Data System (ADS)

Wolfschmidt, Gudrun

As early as the 18th and 19th centuries, French and English observers were active in South Africa. Around the beginning of the 20th century the Heidelberg astronomer Max Wolf (1863-1932) proposed a southern observatory. In 1907 Hermann Carl Vogel (1841-1907), director of the Astrophysical Observatory Potsdam, suggested a southern station in Spain. His ideas for building an observatory in Windhuk for photographing the sky and measuring the solar constant were taken over by the Göttingen astronomers. In 1910 Karl Schwarzschild (1873-1916), after having visited the observatories in America, pointed out the usefulness of an observatory in South West Africa, where it would have better weather than in Germany and also give access to the southern sky. Seeing tests were begun in 1910 by Potsdam astronomers, but WW I stopped the plans. In 1928 Erwin Finlay-Freundlich (1885-1964), inspired by the Hamburg astronomer Walter Baade (1893-1960), worked out a detailed plan for a southern observatory with a reflecting telescope, spectrographs and an astrograph with an objective prism. Paul Guthnick (1879-1947), director of the Berlin observatory, in cooperation with APO Potsdam and Hamburg, made a site survey to Africa in 1929 and found the conditions in Windhuk to be ideal. Observations were started in the 1930s by Berlin and Breslau astronomers, but were stopped by WW II. In the 1950s, astronomers from Hamburg and The Netherlands renewed the discussion in the framework of European cooperation, and this led to the founding of ESO in 1963, as is well described by Blaauw (1991). Blaauw, Adriaan: ESO's Early History. The European Southern Observatory from Concept to Reality. Garching bei München: ESO 1991.

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.

Under Summer Skies

ERIC Educational Resources Information Center

Texley, Juliana

2009-01-01

There's no better way to celebrate 2009, the International Year of Astronomy, than by curling up with a good book under summer skies. To every civilization, in every age, the skies inspired imagination and scientific inquiry. There's no better place to start your summer reading than under their influence. Here are a few selections identified by…

SNAPshot observations of the largest sample of lensed candidates in the Equatorial and Southern Sky identified with Herschel

NASA Astrophysics Data System (ADS)

Marchetti, Lucia

2017-08-01

We propose WFC3/IR F110W Snapshot observations of 200 gravitational lensing systems selected using Herschel submm data taken in all the major Herschel extragalactic surveys (over 850 square degrees). This proposal aims to build upon the successful results of our cycle-19 snapshot (ID:12488) to complete the study of the brightest lensed galaxies ever discovered by Herschel in the Equatorial and Southern Sky. Our successful submm-based selection method identifies lensing events at much higher redshift than any other optical-based selection and is independent of the nature of the magnifier. With these data we will (1) characterize the morphology of the lenses and thus statistically determine what populations are responsible for the gravitational optical depth of the Universe, (2) make accurate fits to the lens light profiles disentangling the foreground lenses from the background sources (3) constrain (and in some cases directly detect) the rest-frame optical emission from the background sources providing estimates of the background source extinction, (4) identify the most extreme star-forming galaxies and rare lensing configurations in the Universe providing the best candidates for future ALMA follow-up, (5) measure the evolution of both the lens mass-density profile, constraing their assembly history, and the lens IMF. This HST program is well-timed with our on-going large spectroscopic program with SALT (3-year program, started in late 2015). This synergy guarantees the timely spectroscopic characterization of our targets securing a long-lasting legacy for this program.

A Remotely Operated Observatory for Minor Planet Photometry

NASA Astrophysics Data System (ADS)

Ditteon, Richard

2008-05-01

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

Sky Subtraction with Fiber-Fed Spectrograph

NASA Astrophysics Data System (ADS)

Rodrigues, Myriam

2017-09-01

"Historically, fiber-fed spectrographs had been deemed inadequate for the observation of faint targets, mainly because of the difficulty to achieve high accuracy on the sky subtraction. The impossibility to sample the sky in the immediate vicinity of the target in fiber instruments has led to a commonly held view that a multi-object fibre spectrograph cannot achieve an accurate sky subtraction under 1% contrary to their slit counterpart. The next generation of multi-objects spectrograph at the VLT (MOONS) and the planed MOS for the E-ELT (MOSAIC) are fiber-fed instruments, and are aimed to observed targets fainter than the sky continuum level. In this talk, I will present the state-of-art on sky subtraction strategies and data reduction algorithm specifically developed for fiber-fed spectrographs. I will also present the main results of an observational campaign to better characterise the sky spatial and temporal variations ( in particular the continuum and faint sky lines)."

Adnyamathanha Night Skies

NASA Astrophysics Data System (ADS)

Curnow, Paul

2009-06-01

Aboriginal Australians have been viewing the night skies of Australia for some 45,000 years and possibly much longer. During this time they have been able to develop a complex knowledge of the night sky, the terrestrial environment in addition to seasonal changes. However, few of us in contemporary society have an in-depth knowledge of the nightly waltz of stars above.

Far infrared all-sky survey

NASA Technical Reports Server (NTRS)

Richards, Paul L.

1991-01-01

An all-sky survey at submillimeter waves is examined. Far-infrared all-sky surveys were performed using high-thoroughput bolometric detectors from a one-meter balloon telescope. Based on the large-bodied experience obtained with the original all-sky survey telescope, a number of radically different approaches were implemented. Continued balloon measurements of the spectrum of the cosmic microwave background were performed.

All-Sky Infrared Survey

NASA Image and Video Library

2009-11-17

This infrared view of the whole sky highlights the flat plane of our Milky Way galaxy line across middle of image. NASA WISE, will take a similar infrared census of the whole sky, only with much improved resolution and sensitivity.

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.

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.

A molecular line study towards massive extended green object clumps in the southern sky: chemical properties

NASA Astrophysics Data System (ADS)

Yu, Naiping; Wang, Jun-Jie

2015-08-01

We present a molecular line study towards 31 extended green object (EGO) clumps in the southern sky using data from MALT90 (Millimetre Astronomy Legacy Team 90 GHz). According to previous multiwavelength observations, we divide our sample into two groups: massive young stellar objects (MYSOs) and H II regions. The most detected lines are N2H+ (J = 1 - 0), HCO+ (J = 1 - 0), HNC (J = 1 - 0), HCN (J = 1 - 0), HC3N (J = 10 - 9), H13CO+ (J = 1 - 0), C2H (N = 1 - 0) and SiO (J = 2 - 1), indicating that most EGOs are indeed associated with dense clumps and recent outflow activities. The velocity widths of the N2H+ (J = 1 - 0), H13CO+ (J = 1 - 0), C2H (N = 1 - 0) and HC3N (J = 10 - 9) lines are comparable to each other in MYSOs. However, in H II regions the velocity widths of the N2H+ (J = 1 - 0) and C2H (N = 1 - 0) lines tend to be narrower than those of H13CO+ (J = 1 - 0) and HC3N (J = 10 - 9). Our results seem to support that N2H+ and C2H emissions mainly come from the gas inside quiescent clumps. In addition, we also find that the [N2H+]/[H13CO+] and [C2H]/[H13CO+] relative abundance ratios decrease from MYSOs to H II regions. These results suggest depletion of N2H+ and C2H in the late stages of massive-star formation, probably caused by the formation of H II regions inside. N2H+ and C2H might be used as chemical clocks for massive-star formation by comparing with other molecules such as H13CO+ and HC3N.

Anisotropy in the all-sky distribution of galaxy morphological types

NASA Astrophysics Data System (ADS)

Javanmardi, Behnam; Kroupa, Pavel

2017-01-01

We present the first study of the isotropy of the all-sky distribution of morphological types of galaxies in the Local Universe out to around 200 Mpc using more than 60 000 galaxies from the HyperLeda database. We use a hemispherical comparison method where the sky is divided into two opposite hemispheres and the abundance distribution of the morphological types, T, are compared using the Kolmogorov-Smirnov (KS) test. By pointing the axis of symmetry of the hemisphere pairs to different directions in the sky, the KS statistic as a function of sky coordinates is obtained. For three samples of galaxies within around 100, 150, and 200 Mpc, we find a significant hemispherical asymmetry with a vanishingly small chance of occurring in an isotropic distribution. Astonishingly, regardless of this extreme significance, the observed hemispherical asymmetry for the three distance ranges is aligned with the celestial equator at the 97.1-99.8% confidence level and with the ecliptic at 94.6-97.6%, estimated using a Monte Carlo analysis. Shifting T values randomly within their uncertainties has a negligible effect on this result. When a magnitude limit of B ≤ 15 mag is applied to these samples, the galaxies within 100 Mpc show no significant anisotropy after randomization of T. However, the direction of the asymmetry in the samples within 150 and 200 Mpc and the same magnitude limit is found to be within an angular separation of 32 degrees from (l,b) = (123.7,24.6) with a 97.2% and 99.9% confidence level, respectively. This direction is only 2.6 degrees away from the celestial north pole. Unless the Local Universe has a significant anisotropic distribution of galaxy morphologies aligned with the orientation or the orbit of the Earth (which would be a challenge for the Cosmological Principle), our results show that there seems to be a systematic bias in the classification of galaxy morphological types between the data from the northern and the southern equatorial sky. Further

Uncertainties of parameterized surface downward clear-sky shortwave and all-sky longwave radiation.

NASA Astrophysics Data System (ADS)

Gubler, S.; Gruber, S.; Purves, R. S.

2012-06-01

As many environmental models rely on simulating the energy balance at the Earth's surface based on parameterized radiative fluxes, knowledge of the inherent model uncertainties is important. In this study we evaluate one parameterization of clear-sky direct, diffuse and global shortwave downward radiation (SDR) and diverse parameterizations of clear-sky and all-sky longwave downward radiation (LDR). In a first step, SDR is estimated based on measured input variables and estimated atmospheric parameters for hourly time steps during the years 1996 to 2008. Model behaviour is validated using the high quality measurements of six Alpine Surface Radiation Budget (ASRB) stations in Switzerland covering different elevations, and measurements of the Swiss Alpine Climate Radiation Monitoring network (SACRaM) in Payerne. In a next step, twelve clear-sky LDR parameterizations are calibrated using the ASRB measurements. One of the best performing parameterizations is elected to estimate all-sky LDR, where cloud transmissivity is estimated using measured and modeled global SDR during daytime. In a last step, the performance of several interpolation methods is evaluated to determine the cloud transmissivity in the night. We show that clear-sky direct, diffuse and global SDR is adequately represented by the model when using measurements of the atmospheric parameters precipitable water and aerosol content at Payerne. If the atmospheric parameters are estimated and used as a fix value, the relative mean bias deviance (MBD) and the relative root mean squared deviance (RMSD) of the clear-sky global SDR scatter between between -2 and 5%, and 7 and 13% within the six locations. The small errors in clear-sky global SDR can be attributed to compensating effects of modeled direct and diffuse SDR since an overestimation of aerosol content in the atmosphere results in underestimating the direct, but overestimating the diffuse SDR. Calibration of LDR parameterizations to local conditions

"Dark Skies, Bright Kids" - First Year Of Outreach In Rural Virginia

NASA Astrophysics Data System (ADS)

Ries, Paul; Johnson, K.; Zasowski, G.; Beaton, R.; Carlberg, J.; Czekala, I.; de Messieres, G.; Drosback, M.; Gugliucci, N.; Jackson, L.; Lynch, R.; Romero, C.; Sivakoff, G.; Whelan, D.; Wong, A.

2010-10-01

Dark Skies, Bright Kids (DSBK) is an educational/public outreach program at the University of Virginia directed primarily towards rural elementary school students in grades 3-5. The program, which is run by a diverse community of volunteers (faculty, postdocs, grad students, and undergrads), targets schools in the rural areas surrounding UVa in southern Albemarle County. While these schools are privileged with remarkably dark skies, these same schools are also home to an economically under-privileged and educationally under-served population. DSBK seeks to use those dark skies, among other resources, to create excitement and interest in science and engineering as part of a weekly after-school program. A typical afternoon consists of 1.5-2.5 hours of science activities specifically centered around space and astronomy. Each week has a theme (e.g., rockets, invisible light) and we incorporate a mix of activities on that theme, such as hands-on experiments, stories, games, and creative play. We also encourage family involvement, so that the parents are actively involved in their children's education. Every other week, we hold a family observing night, so both the students and their parents can learn about the night sky together. The program lasts for one semester at each school, and we have just completed our second semester of work. Each new semester brings on new challenges, but also new lessons to make our program better in future semesters. Our group actively writes and then rewrites our own lesson plans as we learn what works best with the students. We are now in the process of putting our lesson plans online so other groups can take advantage of what we have learned and apply this program at other schools. On the web: http://www.astro.virginia.edu/dsbk/

"Dark Skies, Bright Kids" -- Astronomy Education and Outreach in Rural Virginia

NASA Astrophysics Data System (ADS)

Zasowski, Gail; Johnson, K.; Beaton, R.; Carlberg, J.; Czekala, I.; de Messieres, G.; Drosback, M.; Filipetti, C.; Gugliucci, N.; Hoeft, A.; Jackson, L.; Lynch, R.; Romero, C.; Sivakoff, G.; Whelan, D.; Wong, A.

2010-01-01

In the hills of central Virginia, the extraordinarily dark nighttime skies of southern Albemarle County provide a natural outdoor classroom for local science education. Until recently, this rural area lacked the financial and educational support to take full advantage of this rare and valuable natural resource. With funds provided by the NSF, a team of volunteers from the University of Virginia introduced a new program this fall called "Dark Skies - Bright Kids," which promotes science education at the elementary school level through a wide range of activities. The program volunteers (comprising undergraduate and graduate students, postdocs, and faculty) have sought to develop a coherent schedule of fun and educational activities throughout the semester, with emphases on hands-on learning and critical thinking. For example, students learn about the constellations by making star-wheels, about rocketry by building and launching rockets, and about comets by assembling miniature analogs. Additional activities include stories about the scientific and cultural history of astronomy, visits by professional astronomers and popular book authors, and astronomy-themed exercises in art, music, and physical education. These projects are designed to make astronomy, and by extension all science, accessible and appealing to each student. Family involvement is important in any educational environment, particularly at the elementary school level. To include the students' families and the larger community in "Dark Skies," we hold weekly telescope observing sessions at the school. Here, all interested parties can come together to hear what the students are learning and view astronomical objects through a small telescope. We hope that this well-received program will soon expand to other disadvantaged schools in the area. The "Dark Skies" team is proud and excited to have an impact on the scientific literacy of the students in these starry-skied communities!

Dark Skies as a Universal Resource: Citizen Scientists Measuring Sky Brightness

NASA Astrophysics Data System (ADS)

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

2007-12-01

The international star-hunting event known as GLOBE at Night returned March 8-21, 2007 in two flavors: the classic GLOBE at Night activity incorporating unaided-eye observations which debuted last year, and a new effort to obtain precise measurements of urban dark skies using digital sky-brightness meters. Both flavors of the program were designed to aid in heightening the awareness about 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 make possible the digital GLOBE at Night program, NSF funded 135 low-cost, digital sky-quality meter (manufactured by Unihedron). With these, citizen-scientists took direct measurements of the integrated sky brightness across a wide swath of night sky. Along with related materials developed by the National Optical Astronomy Observatory (NOAO), the meters were distributed to citizen-scientists in 21 U.S. states plus Washington DC, and in 5 other countries, including Chile, where NOAO has a major observatory. The citizen- scientists were selected from teachers, their students, astronomers at mountain-top observatories, International Dark-Sky Association members and staff from 19 small science centers. Most sites had a coordinator, who instructed local educators in the proper use of the meters and develop a plan to share them as widely as possible during the 2-week window. The local teams pooled their data for regional analysis and in some cases shared the results with their schools and local policymakers. Building upon the worldwide participation sparked by the first GLOBE at Night campaign in March 2006, the observations this year approached 8500 (from 60 countries), 85% higher than the number from last year. The success of GLOBE at Night 2007 is a major step toward the International Year of Astronomy in 2009, when one goal is to make the digital data collection into a worldwide activity. In this presentation, we will outline

Light pollution: Assessment of sky glow on two dark sky regions of Portugal.

PubMed

Lima, Raul Cerveira; Pinto da Cunha, José; Peixinho, Nuno

2016-01-01

Artificial light at night (ALAN), producing light pollution (LP), is not a matter restricted to astronomy anymore. Light is part of modern societies and, as a consequence, the natural cycle day-night (bright-dark) has been interrupted in a large segment of the global population. There is increasing evidence that exposure to certain types of light at night and beyond threshold levels may produce hazardous effects to humans and the environment. The concept of "dark skies reserves" is a step forward in order to preserve the night sky and a means of enhancing public awareness of the problem of spread of light pollution worldwide. The aim of this study was to assess the skyglow at two sites in Portugal, the Peneda-Gerês National Park (PNPG) and the region now known as Dark Sky Alqueva Reserve. The latter site was classified as a "Starlight Tourism Destination" by the Starlight Foundation (the first in the world to achieve this classification) following a series of night sky measurements in situ described herein. The measurements at PNPG also contributed to the new set of regulations concerning light pollution at this national park. This study presents the first in situ systematic measurements of night sky brightness, showing that at the two sites the skies are mostly in levels 3 to 4 of the Bortle 9-level scale (with level 1 being the best achievable). The results indicate that the sources of light pollution and skyglow can be attributed predominantly to contamination from nearby urban regions.

Chapter 28: Theory SkyNode

NASA Astrophysics Data System (ADS)

Wagner, R.; Norman, M. L.

Here we present a working example of a Basic SkyNode serving theoretical data. The data is taken from the Simulated Cluster Archive (SCA), a set of simulated X-ray clusters, where each cluster was computed using four different physics models. The LCA Theory SkyNode (LCATheory) tables contain columns of the integrated physical properties of the clusters at various redshifts. The ease of setting up a Theory SkyNode is an important result, because it represents a clear way to present theory data to the Virtual Observatory. Also, our Theory SkyNode provides a prototype for additional simulated object catalogs, which will be created from other simulations by our group, and hopefully others.

The Color of the Sky

NASA Astrophysics Data System (ADS)

Zagury, Frederic

2012-10-01

The color of the sky in day-time and at twilight is studied by means of spectroscopy, which provides an unambiguous way to understand and quantify why a sky is blue, pink, or red. The colors a daylight sky can take primarily owe to Rayleigh extinction and ozone absorption. Spectra of the sky illuminated by the sun can generally be represented by a generic analytical expression which involves the Rayleigh function R ≈ 1/λ^4 e(?a/λ^4), ozone absorption, and, to a lesser extend, aerosol extinction. This study is based on a representative sample of spectra selected from a few hundred observations taken in different places, times, and dates, with a portable fiber spectrometer.

Education for Life in the Sky.

ERIC Educational Resources Information Center

Roth, Charles E.

1981-01-01

The need to educate people about the sky as both a psychological and physical environment is discussed, including a formal curriculum schema (sky as habitat, sky as transport, influence on culture) and informal curriculum, with such topics as recreation, pollution, mythology, and clouds. (DC)

MSDS sky reference and preamplifier study

NASA Technical Reports Server (NTRS)

Larsen, L.; Stewart, S.; Lambeck, P.

1974-01-01

The major goals in re-designing the Multispectral Scanner and Data System (MSDS) sky reference are: (1) to remove the sun-elevation angle and aircraft-attitude angle dependence from the solar-sky illumination measurement, and (2) to obtain data on the optical state of the atmosphere. The present sky reference is dependent on solar elevation and provides essentially no information on important atmospheric parameters. Two sky reference designs were tested. One system is built around a hyperbolic mirror and the reflection approach. A second approach to a sky reference utilizes a fish-eye lens to obtain a 180 deg field of view. A detailed re-design of the present sky reference around the fish-eye approach, even with its limitations, is recommended for the MSDS system. A preamplifier study was undertaken to find ways of improving the noise-equivalent reflectance by reducing the noise level for silicon detector channels on the MSDS.

Measuring night sky brightness: methods and challenges

NASA Astrophysics Data System (ADS)

Hänel, Andreas; Posch, Thomas; Ribas, Salvador J.; Aubé, Martin; Duriscoe, Dan; Jechow, Andreas; Kollath, Zoltán; Lolkema, Dorien E.; Moore, Chadwick; Schmidt, Norbert; Spoelstra, Henk; Wuchterl, Günther; Kyba, Christopher C. M.

2018-01-01

Measuring the brightness of the night sky has become an increasingly important topic in recent years, as artificial lights and their scattering by the Earth's atmosphere continue spreading around the globe. Several instruments and techniques have been developed for this task. We give an overview of these, and discuss their strengths and limitations. The different quantities that can and should be derived when measuring the night sky brightness are discussed, as well as the procedures that have been and still need to be defined in this context. We conclude that in many situations, calibrated consumer digital cameras with fisheye lenses provide the best relation between ease-of-use and wealth of obtainable information on the night sky. While they do not obtain full spectral information, they are able to sample the complete sky in a period of minutes, with colour information in three bands. This is important, as given the current global changes in lamp spectra, changes in sky radiance observed only with single band devices may lead to incorrect conclusions regarding long term changes in sky brightness. The acquisition of all-sky information is desirable, as zenith-only information does not provide an adequate characterization of a site. Nevertheless, zenith-only single-band one-channel devices such as the "Sky Quality Meter" continue to be a viable option for long-term studies of night sky brightness and for studies conducted from a moving platform. Accurate interpretation of such data requires some understanding of the colour composition of the sky light. We recommend supplementing long-term time series derived with such devices with periodic all-sky sampling by a calibrated camera system and calibrated luxmeters or luminance meters.

Dark Skies Rangers - Fighting light pollution and simulating dark skies

NASA Astrophysics Data System (ADS)

Doran, Rosa; Correia, Nelson; Guerra, Rita; Costa, Ana

2015-03-01

Dark Skies Rangers is an awareness program aimed at students of all ages to stimulate them to make an audit of light pollution in their school/district. The young light pollution fighters evaluate the level of light pollution, how much energy is being wasted, and produce a report to be delivered to the local authorities. They are also advised to promote a light pollution awareness campaign to the local community targeting not only the dark skies but also other implications such as effects in our health, to the flora and fauna, etc.

Hunting Mirages in the Southern Sky

NASA Astrophysics Data System (ADS)

1996-02-01

Another Gravitational Lens Candidate Identified at ESO One more cosmic mirage has been found with the ESO 3.5-metre New Technology Telescope (NTT). It consists of two images of the same quasar, seen very close to each other in the southern constellation of Hydra (The Water-Snake). Ever since the exciting discovery of the first cosmic mirage was made seventeen years ago, astronomers have been asking how common this strange phenomenon really is. In most cases we see more than one image of the same celestial object. This effect is due to the bending and focusing of light from distant objects when it passes through the strong gravitational fields of massive galaxies on its way to us. However, from here on the opinions of the specialists diverge. While some believe that this is a very rare event, others disagree and some have even been suggesting that a substantial fraction of the very faint images seen on long exposure photos obtained with large astronomical telescopes may in fact be caused by this effect. If so, they would not be `real'. Is it thus conceivable that the distant Universe is just a great mirror cabinet? There is only one way to answer this important question - more and better observations must be obtained. It is in the course of these investigations that the new discovery was made by a group of three European astronomers [1]. Cosmic mirages are caused by gravitational lenses The physical principle behind a cosmic mirage is known since 1916 as a consequence of Einstein's General Relativity Theory. The gravitational field of a massive object curves the local geometry of the Universe, so light rays passing close to the object are also curved (in the same way as a `straight line' on the surface of the Earth is necessarily curved because of the curvature of the Earth's surface). This effect was first observed by astronomers in 1919 during a total solar eclipse. Accurate positional measurements of stars seen in the dark sky near the eclipsed Sun indicated an

Fireballs in the Sky

NASA Astrophysics Data System (ADS)

Day, B. H.; Bland, P.

2016-12-01

Fireballs in the Sky is an innovative Australian citizen science program that connects the public with the research of the Desert Fireball Network (DFN). This research aims to understand the early workings of the solar system, and Fireballs in the Sky invites people around the world to learn about this science, contributing fireball sightings via a user-friendly app. To date, more than 23,000 people have downloaded the app world-wide and participated in planetary science. The Fireballs in the Sky app allows users to get involved with the Desert Fireball Network research, supplementing DFN observations and providing enhanced coverage by reporting their own meteor sightings to DFN scientists. Fireballs in the Sky reports are used to track the trajectories of meteors - from their orbit in space to where they might have landed on Earth. Led by Phil Bland at Curtin University in Australia, the Desert Fireball Network (DFN) uses automated observatories across Australia to triangulate trajectories of meteorites entering the atmosphere, determine pre-entry orbits, and pinpoint their fall positions. Each observatory is an autonomous intelligent imaging system, taking 1000×36Megapixel all-sky images throughout the night, using neural network algorithms to recognize events. They are capable of operating for 12 months in a harsh environment, and store all imagery collected. We developed a completely automated software pipeline for data reduction, and built a supercomputer database for storage, allowing us to process our entire archive. The DFN currently stands at 50 stations distributed across the Australian continent, covering an area of 2.5 million km^2. Working with DFN's partners at NASA's Solar System Exploration Research Virtual Institute, the team is expanding the network beyond Australia to locations around the world. Fireballs in the Sky allows a growing public base to learn about and participate in this exciting research.

UCAC1: New Proper Motions for 27 Million Stars on the Southern Hemisphere

NASA Astrophysics Data System (ADS)

Zacharias, N.; Monet, S. Urban D. G.; Platais, I.; Wycoff, G. L.; Zacharias, M. I.; Rafferty, T. J.

The big impact of UCAC on galactic kinematics and dynamics studies will be outlined. The USNO CCD Astrograph (UCA) started an astrometric sky survey in February 1998 at Cerro Tololo, Chile. By January 2000 about 90% of the Southern Hemisphere has been observed and full sky coverage is expected by early 2003. In addition, calibration fields around extragalactic reference frame sources and selected open clusters are observed frequently. The UCAC project is a huge dedicated astrometric survey similar to the AGK2 and AGK3 projects but vastly exceeding those with respect to higher accuracy, limiting magnitude (16th) and full sky coverage. A first catalog (UCAC1) is being published in early 2000 for 27 million stars. Stars in the range of 9 to 14th magnitude have a positional precision of 20 mas. The UCAC1 will utilize positions from the USNO A2.0 catalog for determining proper motions, which are expected to be about 8 mas/yr for this initial release. Higher precision proper motions, expected to be in the 3 to 4 mas/yr range, will be derived utilizing a variety of early epoch data, including re-measuring of the Southern Proper Motion (SPM) survey first epoch plates.

Network based sky Brightness Monitor

NASA Astrophysics Data System (ADS)

McKenna, Dan; Pulvermacher, R.; Davis, D. R.

2009-01-01

We have developed and are currently testing an autonomous 2 channel photometer designed to measure the night sky brightness in the visual wavelengths over a multi-year campaign. The photometer uses a robust silicon sensor filtered with Hoya CM500 glass. The Sky brightness is measured every minute at two elevation angles typically zenith and 20 degrees to monitor brightness and transparency. The Sky Brightness monitor consists of two units, the remote photometer and a network interface. Currently these devices use 2.4 Ghz transceivers with a free space range of 100 meters. The remote unit is battery powered with day time recharging using a solar panel. Data received by the network interface transmits data via standard POP Email protocol. A second version is under development for radio sensitive areas using an optical fiber for data transmission. We will present the current comparison with the National Park Service sky monitoring camera. We will also discuss the calibration methods used for standardization and temperature compensation. This system is expected to be deployed in the next year and be operated by the International Dark Sky Association SKYMONITOR project.

Sky-plane discovery rates for Near Earth Object discoveries from Pan-STARRS1 - implications for future search strategies

NASA Astrophysics Data System (ADS)

Wainscoat, Richard J.; Chambers, Kenneth C.; Chastel, Serge; Denneau, Larry; Lilly Schunova, Eva; Micheli, Marco; Weryk, Robert J.

2016-10-01

The Pan-STARRS1 telescope has been spending most of its time for the last 2.5 years searching the sky for Near Earth Objects (NEOs). The surveyed area covers the entire northern sky and extends south to -49 degrees declination. Because Pan-STARRS1 has a large field-of-view, it has been able survey large areas of the sky, and we are now able to examine NEO discovery rates relative to ecliptic latitude.Most contemporary searches, including Pan-STARRS1, have been spending large amounts of their observing time during the dark moon period searching for NEOs close to the ecliptic. The rationale for this is that many objects have low inclination, and all objects in orbit around the Sun must cross the ecliptic. New search capabilities are now available, including Pan-STARRS2, and the upgraded camera in Catalina Sky Survey's G96 telescope. These allow NEO searches to be conducted over wider areas of the sky, and to extend further from the ecliptic.We have examined the discovery rates relative to location on the sky for new NEOs from Pan-STARRS1, and find that the new NEO discoveries are less concentrated on the ecliptic than might be expected. This finding also holds for larger objects. The southern sky has proven to be very productive in new NEO discoveries - this is a direct consequence of the major NEO surveys being located in the northern hemisphere.Our preliminary findings suggest that NEO searches should extend to at least 30 degrees from the ecliptic during the more sensitive dark moon period. At least 6,000 deg2 should therefore be searched each lunation. This is possible with the newly augmented NEO search assets, and repeat coverage will be needed in order to recover most of the NEO candidates found. However, weather challenges will likely make full and repeated coverage of such a large area of sky difficult to achieve. Some simple coordination between observing sites will likely lead to improvement in efficiency.

Shared Skies Partnership: A Dual-Site All-Sky Live Remote Observing Initiative for Research and Education

NASA Astrophysics Data System (ADS)

Kielkopf, John F.; Hart, R.; Carter, B.; Collins, K. A.; Brown, C.; Hay, J.; Hons, A.; Marsden, S.

2014-01-01

The University of Southern Queensland's Mt. Kent Observatory in Queensland, Australia, and the University of Louisville's Moore Observatory in Kentucky, USA, are collaborating in the development of live remote observing for research, student training, and education. With a focus on flexible operation assisted by semi-autonomous controllers, rather than completely robotic data acquisition, the partnership provides interactive hands-on experience to students at all levels, optimized performance based on real-time observations, and flexible scheduling for transient events and targets of opportunity. Two sites on opposites sides of the globe cover the entire sky, and for equatorial regions allow nearly continuous coverage. The facilites include 0.5-m corrected Dall-Kirkham (CDK) telescopes at both sites, a 0.6 m Ritchie-Chretien telescope at Moore, and a new Nasmyth design 0.7-meter CDK at Mt. Kent instrumented for milli-magnitude precision photometry and wide field imaging, with spectrographs under development. We will describe the operational and data acquisition software, recent research results, and how remote access is being made available to students and observers.

A Machine-Learning-Driven Sky Model.

PubMed

Satylmys, Pynar; Bashford-Rogers, Thomas; Chalmers, Alan; Debattista, Kurt

2017-01-01

Sky illumination is responsible for much of the lighting in a virtual environment. A machine-learning-based approach can compactly represent sky illumination from both existing analytic sky models and from captured environment maps. The proposed approach can approximate the captured lighting at a significantly reduced memory cost and enable smooth transitions of sky lighting to be created from a small set of environment maps captured at discrete times of day. The author's results demonstrate accuracy close to the ground truth for both analytical and capture-based methods. The approach has a low runtime overhead, so it can be used as a generic approach for both offline and real-time applications.

Aerosol optical depth under "clear" sky conditions derived from sea surface reflection of lidar signals.

PubMed

He, Min; Hu, Yongxiang; Huang, Jian Ping; Stamnes, Knut

2016-12-26

There are considerable demands for accurate atmospheric correction of satellite observations of the sea surface or subsurface signal. Surface and sub-surface reflection under "clear" atmospheric conditions can be used to study atmospheric correction for the simplest possible situation. Here "clear" sky means a cloud-free atmosphere with sufficiently small aerosol particles. The "clear" aerosol concept is defined according to the spectral dependence of the scattering cross section on particle size. A 5-year combined CALIPSO and AMSR-E data set was used to derive the aerosol optical depth (AOD) from the lidar signal reflected from the sea surface. Compared with the traditional lidar-retrieved AOD, which relies on lidar backscattering measurements and an assumed lidar ratio, the AOD retrieved through the surface reflectance method depends on both scattering and absorption because it is based on two-way attenuation of the lidar signal transmitted to and then reflected from the surface. The results show that the clear sky AOD derived from the surface signal agrees with the clear sky AOD available in the CALIPSO level 2 database in the westerly wind belt located in the southern hemisphere, but yields significantly higher aerosol loadings in the tropics and in the northern hemisphere.

Frequency of College Students' Night-Sky Watching Behaviors

ERIC Educational Resources Information Center

Kelly, William E.; Kelly, Kathryn E.; Batey, Jason

2006-01-01

College students (N = 112) completed the Noctcaelador Inventory, a measure of psychological attachment to the night-sky, and estimated various night-sky watching related activities: frequency and duration of night-sky watching, astro-tourism, ownership of night-sky viewing equipment, and attendance of observatories or planetariums. The results…

Infrared studies of the circumsolar and night sky, April 1968 - 30 November 1971

NASA Technical Reports Server (NTRS)

Peterson, A. W.

1972-01-01

A program is summarized of infrared studies of the circumsolar and night sky conducted between April, 1968, and November 30, 1971, at the University of New Mexico. In addition to observations performed at Capillo Peak Observatory in New Mexico, airborne observations from the Ames Research Center's CV990 were performed in 1968, and eclipses in Siberia (1968) and southern Mexico (1970) were observed. Two dual-channel filter photometers covering wavelengths in the 0.8 to 4.8 micron range were constructed for the aircraft and eclipse observations. A single channel differential photometer was constructed for daytime circumsolar observations. Two large-aperture (12 inch and 24 inch) photometers have been constructed for twilight and night sky photometry. Finally, a small spectrograph for eclipse work has been constructed. It has been used for airglow observations also. Other specialized instrumentation include a four-axis mounting for radial scanning with the eclipse photometers and a 14-inch diameter collimator for use with a black body in calibration of the photometers. The observations performed are included.

Discovery of the Most Ultra-Luminous QSO Using GAIA, SkyMapper, and WISE

NASA Astrophysics Data System (ADS)

Wolf, Christian; Bian, Fuyan; Onken, Christopher A.; Schmidt, Brian P.; Tisserand, Patrick; Alonzi, Noura; Hon, Wei Jeat; Tonry, John L.

2018-06-01

We report the discovery of the ultra-luminous quasi-stellar object SMSS J215728.21-360215.1 with magnitude z = 16.9 and W4 = 7.42 at redshift 4.75. Given absolute magnitudes of M145, AB = -29.3, M300, AB = -30.12, and logLbol/Lbol, ⊙ = 14.84, it is the quasi-stellar object with the highest unlensed UV-optical luminosity currently known in the Universe. It was found by combining proper-motion data from Gaia DR2 with photometry from SkyMapper DR1 and the Wide-field Infrared Survey Explorer. In the GAIA database, it is an isolated single source and thus unlikely to be strongly gravitationally lensed. It is also unlikely to be a beamed source as it is not discovered in the radio domain by either NRAO-VLA Sky Survey or Sydney University Molonglo Southern Survey. It is classed as a weak-emission-line quasi-stellar object and possesses broad absorption line features. A lightcurve from ATLAS spanning the time from 2015 October to 2017 December shows little sign of variability.

SkyNet: Modular nuclear reaction network library

NASA Astrophysics Data System (ADS)

Lippuner, Jonas; Roberts, Luke F.

2017-10-01

The general-purpose nuclear reaction network SkyNet evolves the abundances of nuclear species under the influence of nuclear reactions. SkyNet can be used to compute the nucleosynthesis evolution in all astrophysical scenarios where nucleosynthesis occurs. Any list of isotopes can be evolved and SkyNet supports various different types of nuclear reactions. SkyNet is modular, permitting new or existing physics, such as nuclear reactions or equations of state, to be easily added or modified.

SkyDOT: a publicly accessible variability database, containing multiple sky surveys and real-time data

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

Starr, D. L.; Wozniak, P. R.; Vestrand, W. T.

2002-01-01

SkyDOT (Sky Database for Objects in Time-Domain) is a Virtual Observatory currently comprised of data from the RAPTOR, ROTSE I, and OGLE I1 survey projects. This makes it a very large time domain database. In addition, the RAPTOR project provides SkyDOT with real-time variability data as well as stereoscopic information. With its web interface, we believe SkyDOT will be a very useful tool for both astronomers, and the public. Our main task has been to construct an efficient relational database containing all existing data, while handling a real-time inflow of data. We also provide a useful web interface allowing easymore » access to both astronomers and the public. Initially, this server will allow common searches, specific queries, and access to light curves. In the future we will include machine learning classification tools and access to spectral information.« less

VLITE Surveys the Sky: A 340 MHz Companion to the VLA Sky Survey (VLASS)

NASA Astrophysics Data System (ADS)

Peters, Wendy; Clarke, Tracy; Brisken, Walter; Cotton, William; Richards, Emily E.; Giacintucci, Simona; Kassim, Namir

2018-01-01

The VLA Low Band Ionosphere and Transient Experiment (VLITE; ) is a commensal observing system on the Karl G. Janksy Very Large Array (VLA) which was developed by the Naval Research Laboratory and NRAO. A 64 MHz sub-band from the prime focus 240-470 MHz dipoles is correlated during nearly all regular VLA observations. VLITE uses dedicated samplers and fibers, as well as a custom designed, real-time DiFX software correlator, and requires no additional resources from the VLA system running the primary science program. The experiment has been operating since November 2014 with 10 antennas; a recent expansion in summer 2017 increased that number to 16 and more than doubled the number of baselines.The VLA Sky Survey (VLASS; ), is an ongoing survey of the entire sky visible to the VLA at a frequency of 2-4 GHz. The observations are made using an "on-the-fly" (OTF) continuous RA scanning technique which fills in the sky by observing along rows of constant declination. VLITE breaks the data into 2-second integrations and correlates these at a central position every 1.5 degrees. All data for each correlator position is imaged separately, corrected and weighted by an appropriately elongated primary beam model, and then combined in the image plane to create a mosaic of the sky. A catalog of the sources is extracted to provide a 340 MHz sky model.We present preliminary images and catalogs from the 2017 VLASS observations which began in early September, 2017, and continued on a nearly daily basis throughout the fall. In addition to providing a unique sky model at 340 MHz, these data complement VLASS by providing spectral indices for all cataloged sources.

Daytime Water Detection Based on Sky Reflections

NASA Technical Reports Server (NTRS)

Rankin, Arturo; Matthies, Larry; Bellutta, Paolo

2011-01-01

A water body s surface can be modeled as a horizontal mirror. Water detection based on sky reflections and color variation are complementary. A reflection coefficient model suggests sky reflections dominate the color of water at ranges > 12 meters. Water detection based on sky reflections: (1) geometrically locates the pixel in the sky that is reflecting on a candidate water pixel on the ground (2) predicts if the ground pixel is water based on color similarity and local terrain features. Water detection has been integrated on XUVs.

The sky as a topic in science education

NASA Astrophysics Data System (ADS)

Galili, Igal; Weizman, Ayelet; Cohen, Ariel

2004-07-01

The concepts of sky and visibility distance, as perceived by different learners, are investigated for the first time as a subject of a science education research. Mental models of students with regard to the subject were elicited. They were interpreted in terms of two-level hierarchy: schemes and facets-of-knowledge (defined in the paper). Our results suggest that many students do not consider sky to be a scientific (physical) concept. The majority perceives the sky as having an oblate profile. Among the parameters that determine this profile were mentioned daytime, atmosphere, geometry of the situation, and weather conditions. The students hold two major explanatory views (schemes) with regard to the sky: the sky is the atmosphere and the sky is the appearance of space. With regard to the visibility distance, the two following schemes prevail: vision weakens with the distance and natural obstacles determine vision distance. No significant correlation was found between the views regarding the sky appearance and the vision distance. Students do not relate Moon illusion to the profile of sky or visibility distance. The notions of sky and visibility distance are argued for inclusion into science curriculum, and implications of the findings to a constructivist instruction of the considered concepts and phenomena are discussed.

Dark Skies, Bright Kids: Year 2

NASA Astrophysics Data System (ADS)

Carlberg, Joleen K.; Johnson, K.; Lynch, R.; Walker, L.; Beaton, R.; Corby, J.; de Messieres, G.; Drosback, M.; Gugliucci, N.; Jackson, L.; Kingery, A.; Layman, S.; Murphy, E.; Richardson, W.; Ries, P.; Romero, C.; Sivakoff, G.; Sokal, K.; Trammell, G.; Whelan, D.; Yang, A.; Zasowski, G.

2011-01-01

The Dark Skies, Bright Kids (DSBK) outreach program brings astronomy education into local elementary schools in central Virginia's Southern Albemarle County through an after-school club. Taking advantage of the unusually dark night skies in the rural countryside, DSBK targets economically disadvantaged schools that tend to be underserved due to their rural locale. The goals of DSBK are to foster children's natural curiosity, demonstrate that science is a fun and creative process, challenge students' conceptions of what a scientist is and does, and teach some basic astronomy. Furthermore, DSBK works to assimilate families into students' education by holding family observing nights at the school. Now in its third semester, DSBK has successfully run programs at two schools with very diverse student populations. Working with these students has helped us to revise our activities and to create new ones. A by-product of our work has been the development of lesson plans, complete with learning goals and detailed instructions, that we make publically available on our website. This year we are expanding our repertoire with our new planetarium, which allows us to visualize topics in novel ways and supplements family observing on cloudy nights. The DSBK volunteers have also created a bilingual astronomy artbook --- designed, written, and illustrated by UVa students --- that we will publish and distribute to elementary schools in Virginia. Our book debuted at the last AAS winter meeting, and since then it has been extensively revised and updated with input from many individuals, including parents, professional educators, and a children's book author. Because the club is currently limited to serving a few elementary schools, this book will be part of our efforts to broaden our impact by bringing astronomy to schools we cannot go to ourselves and reaching out to Spanish-speaking communities at the same time.

The Solar Neighborhood. XXVII. Discovery of New Proper Motion Stars with μ >= 0farcs18 yr-1 in the Southern Sky with 16.5 < R 59F <= 18.0

NASA Astrophysics Data System (ADS)

Boyd, Mark R.; Henry, Todd J.; Jao, Wei-Chun; Subasavage, John P.; Hambly, Nigel C.

2011-09-01

Here we present 1584 new southern proper motion systems with μ >= 0farcs18 yr-1 and 16.5 > R 59F >= 18.0. This search complements the six previous SuperCOSMOS-RECONS (SCR) proper motion searches of the southern sky for stars within the same proper motion range, but with R 59F <= 16.5. As in previous papers, we present distance estimates for these systems and find that three systems are estimated to be within 25 pc, including one, SCR 1546-5534, possibly within the RECONS 10 pc horizon at 6.7 pc, making it the second nearest discovery of the searches. We find 97 white dwarf candidates with distance estimates between 10 and 120 pc, as well as 557 cool subdwarf candidates. The subdwarfs found in this paper make up nearly half of the subdwarf systems reported from our SCR searches and are significantly redder than those discovered thus far. The SCR searches have now found 155 red dwarfs estimated to be within 25 pc, including 10 within 10 pc. In addition, 143 white dwarf candidates and 1155 cool subdwarf candidates have been discovered. The 1584 systems reported here augment the sample of 4724 systems previously discovered in our SCR searches and imply that additional systems fainter than R 59F = 18.0 are yet to be discovered.

Educating for the Preservation of Dark Skies

NASA Astrophysics Data System (ADS)

Preston, Sandra Lee; Cianciolo, Frank; Wetzel, Marc; Finkelstein, Keely; Wren, William; Nance, Craig

2015-08-01

The stars at night really are big and bright deep in the heart of Texas at the McDonald Observatory near Fort Davis, Texas. Each year 80,000 visitors from all over the world make the pilgrimage to the Observatory to attend one of the three-times-a-week star parties. Many experience, for the first time, the humbling, splendor of a truly dark night sky. Over the last several years, the Observatory has experienced dramatic increases in visitation demonstrating the public’s appetite for science education, in general, and interest in the night sky, in particular. This increasing interest in astronomy is, ironically, occurring at a time when most of humanity’s skies are becoming increasingly light-polluted frustrating this natural interest. Dark skies and knowledgeable education and outreach staff are an important resource in maintaining the public’s interest in astronomy, support for astronomical research, and local tourism.This year Observatory educators were inspired by the observance of the International Year of Light to promote healthy outdoor lighting through its popular Astronomy Day distance learning program. This program reaches tens of thousands of K-12 students in Texas and other states with a message of how they can take action to preserve dark skies. As well, more than a thousand Boy Scouts visiting during the summer months receive a special program, which includes activities focusing on good lighting practices, thereby earning them credits toward an astronomy badge.The Observatory also offers a half-a-dozen K-12 teacher professional development workshops onsite each year, which provide about 90 teachers with dark skies information, best-practice lighting demonstrations, and red flashlights. Multi-year workshops for National Park and State of Texas Parks personnel are offered on dark sky preservation and sky interpretation at McDonald and a Dark Skies fund for retrofitting lights in the surrounding area has been established. The Observatory also uses

Cloud fractions estimated from shipboard whole-sky camera and ceilometer observations between East Asia and Antarctica

NASA Astrophysics Data System (ADS)

Kuji, M.; Hagiwara, M.; Hori, M.; Shiobara, M.

2017-12-01

Shipboard observations on cloud fraction were carried out along the round research cruise between East Asia and Antarctica from November 2015 to Aril 2016 using a whole-sky camera and a ceilometer onboard Research Vessel (R/V) Shirase. We retrieved cloud fraction from the whole-sky camera based on the brightness and color of the images, while we estimated cloud fraction from the ceilometer as a cloud frequency of occurrence. As a result, the average cloud fractions over outward open ocean, sea ice region, and returning openocean were approximately 56% (60%), 44% (64%), and 67% (72%), respectively, with the whole-sky camera (ceilometer). The comparison of the daily-averaged cloud fractions from the whole-sky camera and the ceilometer, it is found that the correlation coefficient was 0.73 for the 129 match-up dataset between East Asia and Antarctica including sea ice region as well as open ocean. The results are qualitatively consistent between the two observations as a whole, but there exists some underestimation with the whole-sky camera compared to the ceilometer. One of the reasons is possibly that the imager is apt to dismiss an optically thinner clouds that can be detected by the ceilometer. On the other hand, the difference of their view angles between the imager and the ceilometer possibly affects the estimation. Therefore, it is necessary to elucidate the cloud properties with detailed match-up analyses in future. Another future task is to compare the cloud fractions with satellite observation such as MODIS cloud products. Shipboard observations in themselves are very valuable for the validation of products from satellite observation, because we do not necessarily have many validation sites over Southern Ocean and sea ice region in particular.

Maps of the Southern Millimeter-wave Sky from Combined 2500 deg$^2$ SPT-SZ and Planck Temperature Data

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

Chown, R.; et al.

We present three maps of the millimeter-wave sky created by combining data from the South Pole Telescope (SPT) and the Planck satellite. We use data from the SPT-SZ survey, a survey of 2540 deg$^2$ of the the sky with arcminute resolution in three bands centered at 95, 150, and 220 GHz, and the full-mission Planck temperature data in the 100, 143, and 217 GHz bands. A linear combination of the SPT-SZ and Planck data is computed in spherical harmonic space, with weights derived from the noise of both instruments. This weighting scheme results in Planck data providing most of themore » large-angular-scale information in the combined maps, with the smaller-scale information coming from SPT-SZ data. A number of tests have been done on the maps. We find their angular power spectra to agree very well with theoretically predicted spectra and previously published results.« less

Entire Sky

NASA Image and Video Library

1999-12-01

Aitoff projection of the three-color composite JHKs source count map of the entire sky, based on 95,851,173 stars with Ks 13.5. What appears most prominently are the Galactic plane and the Galactic bulge.

The Sky This Week - Naval Oceanography Portal

Science.gov Websites

section Advanced Search... Sections Home Time Earth Orientation Astronomy Meteorology Oceanography Ice You . Read More... The Sky This Week, 2018 April 17 - 24 Celebrate Dark-sky Week and Astronomy Day! Read More More... The Sky This Week, 2018 April 3 - 10 April is Astronomy Month...no fooling. Read More... The

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.

Where is the sky?

NASA Astrophysics Data System (ADS)

Cohen, Ariel; Galili, Igal

2001-02-01

This paper discusses the origin of the concept of sky. It is shown to emerge from one's experience of the visual perception of nonluminous objects observed in/through the atmosphere during the daytime. The physical concept of visibility in the atmospheric environment underpins the perception of a flattened sky dome constructed by our mind. In addition, the Moon illusion receives a plausible explanation and both topics become appropriate for a conceptually oriented introduction course in physics and/or astronomy.

Scanning sky monitor (SSM) onboard AstroSat

NASA Astrophysics Data System (ADS)

Ramadevi, M. C.; Seetha, S.; Bhattacharya, Dipankar; Ravishankar, B. T.; Sitaramamurthy, N.; Meena, G.; Sharma, M. Ramakrishna; Kulkarni, Ravi; Babu, V. Chandra; Kumar; Singh, Brajpal; Jain, Anand; Yadav, Reena; Vaishali, S.; Ashoka, B. N.; Agarwal, Anil; Balaji, K.; Nagesh, G.; Kumar, Manoj; Gaan, Dhruti Ranjan; Kulshresta, Prashanth; Agarwal, Pankaj; Sebastian, Mathew; Rajarajan, A.; Radhika, D.; Nandi, Anuj; Girish, V.; Agarwal, Vivek Kumar; Kushwaha, Ankur; Iyer, Nirmal Kumar

2017-10-01

Scanning Sky Monitor (SSM) onboard AstroSat is an Xray sky monitor in the soft X-ray band designed with a large field of view to detect and locate transient X-ray sources and alert the astronomical community about interesting phenomena in the X-ray sky. SSM comprises position sensitive proportional counters with 1D coded mask for imaging. There are three detector units mounted on a platform capable of rotation which helps covering about 50% of the sky in one full rotation. This paper discusses the elaborate details of the instrument and few immediate results from the instrument after launch.

Daytime sky polarization calibration limitations

NASA Astrophysics Data System (ADS)

Harrington, David M.; Kuhn, Jeffrey R.; Ariste, Arturo López

2017-01-01

The daytime sky has recently been demonstrated as a useful calibration tool for deriving polarization cross-talk properties of large astronomical telescopes. The Daniel K. Inouye Solar Telescope and other large telescopes under construction can benefit from precise polarimetric calibration of large mirrors. Several atmospheric phenomena and instrumental errors potentially limit the technique's accuracy. At the 3.67-m AEOS telescope on Haleakala, we performed a large observing campaign with the HiVIS spectropolarimeter to identify limitations and develop algorithms for extracting consistent calibrations. Effective sampling of the telescope optical configurations and filtering of data for several derived parameters provide robustness to the derived Mueller matrix calibrations. Second-order scattering models of the sky show that this method is relatively insensitive to multiple-scattering in the sky, provided calibration observations are done in regions of high polarization degree. The technique is also insensitive to assumptions about telescope-induced polarization, provided the mirror coatings are highly reflective. Zemax-derived polarization models show agreement between the functional dependence of polarization predictions and the corresponding on-sky calibrations.

SkyProbeBV: dual-color absolute sky transparency monitor to optimize science operations

NASA Astrophysics Data System (ADS)

Cuillandre, Jean-Charles; Magnier, Eugene; Sabin, Dan; Mahoney, Billy

2008-07-01

Mauna Kea (4200 m elevation, Hawaii) is known for its pristine seeing conditions, but sky transparency can be an issue for science operations: 25% of the nights are not photometric, a cloud coverage mostly due to high-altitude thin cirrus. The Canada-France-Hawaii Telescope (CFHT) is upgrading its real-time sky transparency monitor in the optical domain (V-band) into a dual-color system by adding a B-band channel and redesigning the entire optical and mechanical assembly. Since 2000, the original single-channel SkyProbe has gathered one exposure every minute during each observing night using a small CCD camera with a very wide field of view (35 sq. deg.) encompassing the region pointed by the telescope for science operations, and exposures long enough (30 seconds) to capture at least 100 stars of Hipparcos' Tychos catalog at high galactic latitudes (and up to 600 stars at low galactic latitudes). A key advantage of SkyProbe over direct thermal infrared imaging detection of clouds, is that it allows an accurate absolute measurement, within 5%, of the true atmospheric absorption by clouds affecting the data being gathered by the telescope's main science instrument. This system has proven crucial for decision making in the CFHT queued service observing (QSO), representing today 95% of the telescope time: science exposures taken in non-photometric conditions are automatically registered for being re-observed later on (at 1/10th of the original exposure time per pointing in the observed filters) to ensure a proper final absolute photometric calibration. If the absorption is too high, exposures can be repeated, or the observing can be done for a lower ranked science program. The new dual color system (simultaneous B & V bands) will allow a better characterization of the sky properties above Mauna Kea and should enable a better detection of the thinner cirrus (absorption down to 0.02 mag., i.e. 2%). SkyProbe is operated within the Elixir pipeline, a collection of tools

Custom Sky-Image Mosaics from NASA's Information Power Grid

NASA Technical Reports Server (NTRS)

Jacob, Joseph; Collier, James; Craymer, Loring; Curkendall, David

2005-01-01

yourSkyG is the second generation of the software described in yourSky: Custom Sky-Image Mosaics via the Internet (NPO-30556), NASA Tech Briefs, Vol. 27, No. 6 (June 2003), page 45. Like its predecessor, yourSkyG supplies custom astronomical image mosaics of sky regions specified by requesters using client computers connected to the Internet. Whereas yourSky constructs mosaics on a local multiprocessor system, yourSkyG performs the computations on NASA s Information Power Grid (IPG), which is capable of performing much larger mosaicking tasks. (The IPG is high-performance computation and data grid that integrates geographically distributed 18 NASA Tech Briefs, September 2005 computers, databases, and instruments.) A user of yourSkyG can specify parameters describing a mosaic to be constructed. yourSkyG then constructs the mosaic on the IPG and makes it available for downloading by the user. The complexities of determining which input images are required to construct a mosaic, retrieving the required input images from remote sky-survey archives, uploading the images to the computers on the IPG, performing the computations remotely on the Grid, and downloading the resulting mosaic from the Grid are all transparent to the user

The Python Sky Model: software for simulating the Galactic microwave sky

NASA Astrophysics Data System (ADS)

Thorne, B.; Dunkley, J.; Alonso, D.; Næss, S.

2017-08-01

We present a numerical code to simulate maps of Galactic emission in intensity and polarization at microwave frequencies, aiding in the design of cosmic microwave background experiments. This python code builds on existing efforts to simulate the sky by providing an easy-to-use interface and is based on publicly available data from the WMAP (Wilkinson Microwave Anisotropy Probe) and Planck satellite missions. We simulate synchrotron, thermal dust, free-free and anomalous microwave emission over the whole sky, in addition to the cosmic microwave background, and include a set of alternative prescriptions for the frequency dependence of each component, for example, polarized dust with multiple temperatures and a decorrelation of the signals with frequency, which introduce complexity that is consistent with current data. We also present a new prescription for adding small-scale realizations of these components at resolutions greater than current all-sky measurements. The usefulness of the code is demonstrated by forecasting the impact of varying foreground complexity on the recovered tensor-to-scalar ratio for the LiteBIRD satellite. The code is available at: https://github.com/bthorne93/PySM_public.

Dark Skies: Local Success, Global Challenge

NASA Astrophysics Data System (ADS)

Lockwood, G. W.

2009-01-01

The Flagstaff, Arizona 1987 lighting code reduced the growth rate of man-made sky glow by a third. Components of the code include requirements for full cutoff lighting, lumens per acre limits in radial zones around observatories, and use of low-pressure sodium monochromatic lighting for roadways and parking lots. Broad public acceptance of Flagstaff's lighting code demonstrates that dark sky preservation has significant appeal and few visibility or public safety negatives. An inventory by C. Luginbuhl et al. of the light output and shielding of a sampling of various zoning categories (municipal, commercial, apartments, single-family residences, roadways, sports facilities, industrial, etc.), extrapolated over the entire city, yields a total output of 139 million lumens. Commercial and industrial sources account for 62% of the total. Outdoor sports lighting increases the total by 24% on summer evenings. Flagstaff's per capita lumen output is 2.5 times greater than the nominal 1,000 lumens per capita assumed by R. Garstang in his early sky glow modeling work. We resolved the discrepancy with respect to Flagstaff's measured sky glow using an improved model that includes substantial near ground attenuation by foliage and structures. A 2008 university study shows that astronomy contributes $250M annually to Arizona's economy. Another study showed that the application of lighting codes throughout Arizona could reduce energy consumption significantly. An ongoing effort led by observatory directors statewide will encourage lighting controls in currently unregulated metropolitan areas whose growing sky glow threatens observatory facilities more than 100 miles away. The national press (New York Times, the New Yorker, the Economist, USA Today, etc.) have publicized dark sky issues but frequent repetition of the essential message and vigorous action will be required to steer society toward darker skies and less egregious waste.

Spectral and Spatial UV Sky Radiance Measurements at a Seaside Resort Under Clear Sky and Slightly Overcast Conditions.

PubMed

Sandmann, Henner; Stick, Carsten

2014-01-01

Spatial measurements of the diffusely scattered sky radiance at a seaside resort under clear sky and slightly overcast conditions have been used to calculate the sky radiance distribution across the upper hemisphere. The measurements were done in the summer season when solar UV radiation is highest. The selected wavelengths were 307, 350 and 550 nm representing the UVB, UVA and VIS band. Absolute values of radiance differ considerably between the wavelengths. Normalizing the measured values by use of direct solar radiance made the spatial distributions of unequal sky radiance comparable. The results convey a spatial impression of the different distributions of the radiance at the three wavelengths. Relative scattered radiance intensity is one order of magnitude greater in UVB than in VIS, whereas in UVA lies roughly in between. Under slightly overcast conditions scattered radiance is increased at all three wavelengths by about one order of magnitude. These measurements taken at the seaside underline the importance of diffuse scattered radiance. The effect of shading parts of the sky can be estimated from the distribution of sky radiance. This knowledge might be useful for sun seekers and in the treatment of people staying at the seaside for therapeutic purposes. © 2013 The American Society of Photobiology.

Angles in the Sky?

NASA Astrophysics Data System (ADS)

Behr, Bradford

2005-09-01

Tycho Brahe lived and worked in the late 1500s before the telescope was invented. He made highly accurate observations of the positions of planets, stars, and comets using large angle-measuring devices of his own design. You can use his techniques to observe the sky as well. For example, the degree, a common unit of measurement in astronomy, can be measured by holding your fist at arm's length up to the sky. Open your fist and observe the distance across the sky covered by the width of your pinky fingernail. That is, roughly, a degree! After some practice, and knowing that one degree equals four minutes, you can measure elapsed time by measuring the angle of the distance that the Moon appears to have moved and multiplying that number by four. You can also figure distances and sizes of things. These are not precise measurements, but rough estimates that can give you a "close-enough" answer.

Hartung's Astronomical Objects for Southern Telescopes

NASA Astrophysics Data System (ADS)

Malin, David; Frew, David J.

1995-10-01

Many of the most spectacular astronomical objects are found in the southern skies. With this up-to-date, superbly illustrated handbook, both the amateur with binoculars and the expert with a telescope can make discoveries about new and interesting objects. Professor E. J. Hartung first produced his comprehensive and highly respected guide in 1968. Now the book has been greatly expanded and thoroughly revised, enhancing its character as an indispensable information source. With over 150 illustrations, new material is included on constellations and celestial coordinate systems as well as more modern descriptions of stars, nebulae and galaxies. The authors have included a new "southern Messier" list of objects. The authors' passion for their subject make this a unique and inspirational book. Many of the beautiful photographs were taken by David Malin, the world's leading astronomical photographer. The result will fascinate active and armchair astronomers alike.

Planck View of the Whole Sky

NASA Image and Video Library

2010-07-06

This image of the microwave sky was synthesized using data spanning the range of light frequencies detected by ESA Planck. A vast portion of the sky is dominated by the diffuse emission from gas and dust in our Milky Way galaxy.

The Multi-site All-Sky CAmeRA (MASCARA). Finding transiting exoplanets around bright (mV < 8) stars

NASA Astrophysics Data System (ADS)

Talens, G. J. J.; Spronck, J. F. P.; Lesage, A.-L.; Otten, G. P. P. L.; Stuik, R.; Pollacco, D.; Snellen, I. A. G.

2017-05-01

This paper describes the design, operations, and performance of the Multi-site All-Sky CAmeRA (MASCARA). Its primary goal is to find new exoplanets transiting bright stars, 4 < mV < 8, by monitoring the full sky. MASCARA consists of one northern station on La Palma, Canary Islands (fully operational since February 2015), one southern station at La Silla Observatory, Chile (operational from early 2017), and a data centre at Leiden Observatory in the Netherlands. Both MASCARA stations are equipped with five interline CCD cameras using wide field lenses (24 mm focal length) with fixed pointings, which together provide coverage down to airmass 3 of the local sky. The interline CCD cameras allow for back-to-back exposures, taken at fixed sidereal times with exposure times of 6.4 sidereal seconds. The exposures are short enough that the motion of stars across the CCD does not exceed one pixel during an integration. Astrometry and photometry are performed on-site, after which the resulting light curves are transferred to Leiden for further analysis. The final MASCARA archive will contain light curves for 70 000 stars down to mV = 8.4, with a precision of 1.5% per 5 minutes at mV = 8.

Sky Sculpture.

ERIC Educational Resources Information Center

Woody, Howard

1980-01-01

Described is a five-day workshop in the new environmental art form of sky sculpture, which was presented at Wingfield High School in Jackson, Mississippi. Included are daily activities and the design considerations faced by students when planning their balloon creations for flight. (SJL)

Observations of southern emission-line stars

NASA Technical Reports Server (NTRS)

Henize, K. G.

1976-01-01

A catalog of 1929 stars showing H-alpha emission on photographic plates is presented which covers the entire southern sky south of declination -25 deg to a red limiting magnitude of about 11.0. The catalog provides previous designations of known emission-line stars equatorial (1900) and galactic coordinates, visual and photographic magnitudes, H-alpha emission parameters, spectral types, and notes on unusual spectral features. The objects listed include 16 M stars, 25 S stars, 37 carbon stars, 20 symbiotic stars, 40 confirmed or suspected T Tauri stars, 16 novae, 14 planetary nebulae, 11 P Cygni stars, 9 Bep stars, 87 confirmed or suspected Wolf-Rayet stars, and 26 'peculiar' stars. Two new T associations are discovered, one in Lupus and one in Chamaeleon. Objects with variations in continuum or H-alpha intensity are noted, and the distribution by spectral type is analyzed. It is found that the sky distribution of these emission-line stars shows significant concentrations in the region of the small Sagittarius cloud and in the Carina region.

An optical to IR sky brightness model for the LSST

NASA Astrophysics Data System (ADS)

Yoachim, Peter; Coughlin, Michael; Angeli, George Z.; Claver, Charles F.; Connolly, Andrew J.; Cook, Kem; Daniel, Scott; Ivezić, Željko; Jones, R. Lynne; Petry, Catherine; Reuter, Michael; Stubbs, Christopher; Xin, Bo

2016-07-01

To optimize the observing strategy of a large survey such as the LSST, one needs an accurate model of the night sky emission spectrum across a range of atmospheric conditions and from the near-UV to the near-IR. We have used the ESO SkyCalc Sky Model Calculator1, 2 to construct a library of template spectra for the Chilean night sky. The ESO model includes emission from the upper and lower atmosphere, scattered starlight, scattered moonlight, and zodiacal light. We have then extended the ESO templates with an empirical fit to the twilight sky emission as measured by a Canon all-sky camera installed at the LSST site. With the ESO templates and our twilight model we can quickly interpolate to any arbitrary sky position and date and return the full sky spectrum or surface brightness magnitudes in the LSST filter system. Comparing our model to all-sky observations, we find typical residual RMS values of +/-0.2-0.3 magnitudes per square arcsecond.

Infrared Sky Surveys

NASA Astrophysics Data System (ADS)

Price, Stephan D.

2009-02-01

A retrospective is given on infrared sky surveys from Thomas Edison’s proposal in the late 1870s to IRAS, the first sensitive mid- to far-infrared all-sky survey, and the mid-1990s experiments that filled in the IRAS deficiencies. The emerging technology for space-based surveys is highlighted, as is the prominent role the US Defense Department, particularly the Air Force, played in developing and applying detector and cryogenic sensor advances to early mid-infrared probe-rocket and satellite-based surveys. This technology was transitioned to the infrared astronomical community in relatively short order and was essential to the success of IRAS, COBE and ISO. Mention is made of several of the little known early observational programs that were superseded by more successful efforts.

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.

A serendipitous all sky survey for bright objects in the outer solar system

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

Brown, M. E.; Drake, A. J.; Djorgovski, S. G.

2015-02-01

We use seven year's worth of observations from the Catalina Sky Survey and the Siding Spring Survey covering most of the northern and southern hemisphere at galactic latitudes higher than 20° to search for serendipitously imaged moving objects in the outer solar system. These slowly moving objects would appear as stationary transients in these fast cadence asteroids surveys, so we develop methods to discover objects in the outer solar system using individual observations spaced by months, rather than spaced by hours, as is typically done. While we independently discover eight known bright objects in the outer solar system, the faintestmore » having V=19.8±0.1, no new objects are discovered. We find that the survey is nearly 100% efficient at detecting objects beyond 25 AU for V≲19.1 (V≲18.6 in the southern hemisphere) and that the probability that there is one or more remaining outer solar system object of this brightness left to be discovered in the unsurveyed regions of the galactic plane is approximately 32%.« less

"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.

Variability of adjacency effects in sky reflectance measurements.

PubMed

Groetsch, Philipp M M; Gege, Peter; Simis, Stefan G H; Eleveld, Marieke A; Peters, Steef W M

2017-09-01

Sky reflectance R sky (λ) is used to correct in situ reflectance measurements in the remote detection of water color. We analyzed the directional and spectral variability in R sky (λ) due to adjacency effects against an atmospheric radiance model. The analysis is based on one year of semi-continuous R sky (λ) observations that were recorded in two azimuth directions. Adjacency effects contributed to R sky (λ) dependence on season and viewing angle and predominantly in the near-infrared (NIR). For our test area, adjacency effects spectrally resembled a generic vegetation spectrum. The adjacency effect was weakly dependent on the magnitude of Rayleigh- and aerosol-scattered radiance. The reflectance differed between viewing directions 5.4±6.3% for adjacency effects and 21.0±19.8% for Rayleigh- and aerosol-scattered R sky (λ) in the NIR. Under which conditions in situ water reflectance observations require dedicated correction for adjacency effects is discussed. We provide an open source implementation of our method to aid identification of such conditions.

Spatiotemporal change of sky polarization during the total solar eclipse on 29 March 2006 in Turkey: polarization patterns of the eclipsed sky observed by full-sky imaging polarimetry.

PubMed

Sipocz, Brigitta; Hegedüs, Ramón; Kriska, György; Horváth, Gábor

2008-12-01

Using 180 degrees field-of-view (full-sky) imaging polarimetry, we measured the spatiotemporal change of the polarization of skylight during the total solar eclipse on 29 March 2006 in Turkey. We present our observations here on the temporal variation of the celestial patterns of the degree p and angle alpha of linear polarization of the eclipsed sky measured in the red (650 nm), green (550 nm), and blue (450 nm) parts of the spectrum. We also report on the temporal and spectral change of the positions of neutral (unpolarized, p = 0) points, and points with local minima or maxima of p of the eclipsed sky. Our results are compared with the observations performed by the same polarimetric technique during the total solar eclipse on 11 August 1999 in Hungary. Practically the same characteristics of celestial polarization were encountered during both eclipses. This shows that the observed polarization phenomena of the eclipsed sky may be general.

High-Resolution Spectroscopic Study of Extremely Metal-Poor Star Candidates from the SkyMapper Survey

NASA Astrophysics Data System (ADS)

Jacobson, Heather R.; Keller, Stefan; Frebel, Anna; Casey, Andrew R.; Asplund, Martin; Bessell, Michael S.; Da Costa, Gary S.; Lind, Karin; Marino, Anna F.; Norris, John E.; Peña, José M.; Schmidt, Brian P.; Tisserand, Patrick; Walsh, Jennifer M.; Yong, David; Yu, Qinsi

2015-07-01

The SkyMapper Southern Sky Survey is carrying out a search for the most metal-poor stars in the Galaxy. It identifies candidates by way of its unique filter set which allows for estimation of stellar atmospheric parameters. The set includes a narrow filter centered on the Ca ii K 3933 Å line, enabling a robust estimate of stellar metallicity. Promising candidates are then confirmed with spectroscopy. We present the analysis of Magellan Inamori Kyocera Echelle high-resolution spectroscopy of 122 metal-poor stars found by SkyMapper in the first two years of commissioning observations. Forty-one stars have [{Fe}/{{H}}]≤slant -3.0. Nine have [{Fe}/{{H}}]≤slant -3.5, with three at [{Fe}/{{H}}]∼ -4. A 1D LTE abundance analysis of the elements Li, C, Na, Mg, Al, Si, Ca, Sc, Ti, Cr, Mn, Co, Ni, Zn, Sr, Ba, and Eu shows these stars have [X/Fe] ratios typical of other halo stars. One star with low [X/Fe] values appears to be “Fe-enhanced,” while another star has an extremely large [Sr/Ba] ratio: \\gt 2. Only one other star is known to have a comparable value. Seven stars are “CEMP-no” stars ([{{C}}/{Fe}]\\gt 0.7, [{Ba}/{Fe}]\\lt 0). 21 stars exhibit mild r-process element enhancements (0.3≤slant [{Eu}/{Fe}]\\lt 1.0), while four stars have [{Eu}/{Fe}]≥slant 1.0. These results demonstrate the ability to identify extremely metal-poor stars from SkyMapper photometry, pointing to increased sample sizes and a better characterization of the metal-poor tail of the halo metallicity distribution function in the future. This paper includes data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile.

First photometric study of two southern eclipsing binaries IS Tel and DW Aps

NASA Astrophysics Data System (ADS)

Özer, S.; Sürgit, D.; Erdem, A.; Öztürk, O.

2017-02-01

The paper presents the first photometric analysis of two southern eclipsing binary stars, IS Tel and DW Aps. Their V light curves from the All Sky Automated Survey were modelled by using Wilson-Devinney method. The final models give these two Algol-like binary stars as having detached configurations. Absolute parameters of the components of the systems were also estimated.

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

Zernike analysis of all-sky night brightness maps.

PubMed

Bará, Salvador; Nievas, Miguel; Sánchez de Miguel, Alejandro; Zamorano, Jaime

2014-04-20

All-sky night brightness maps (calibrated images of the night sky with hemispherical field-of-view (FOV) taken at standard photometric bands) provide useful data to assess the light pollution levels at any ground site. We show that these maps can be efficiently described and analyzed using Zernike circle polynomials. The relevant image information can be compressed into a low-dimensional coefficients vector, giving an analytical expression for the sky brightness and alleviating the effects of noise. Moreover, the Zernike expansions allow us to quantify in a straightforward way the average and zenithal sky brightness and its variation across the FOV, providing a convenient framework to study the time course of these magnitudes. We apply this framework to analyze the results of a one-year campaign of night sky brightness measurements made at the UCM observatory in Madrid.

The New Progress of the Starry Sky Project of China

NASA Astrophysics Data System (ADS)

Wang, Xiaohua

2015-08-01

Since the 28th General Assembly of IAU, the SSPC team made new progress:1. Enhanced the function of the SSPC team-- Established the contact with IAU C50, IUCN Dark Skies Advisory Group, AWB and IDA,and undertakes the work of the IDA Beijing Chapter.-- Got supports from China’s National Astronomical Observatories, Beijing Planetarium, and Shanghai Science and Technology Museum.-- Signed cooperation agreements with Lighting Research Center, English Education Group and law Firm; formed the team force.2. Put forward a proposal to national top institutionThe SSPC submitted the first proposal about dark sky protection to the Chinese People’s Political Consultative Conference.3. Introduced the Criteria and Guideline of dark sky protectionThe SSPC team translated 8 documents of IDA, and provided a reference basis for Chinese dark sky protection.4. Actively establish dark sky places-- Plan a Dark Sky Reserve around Ali astronomical observatory (5,100m elevation) in Tibet. China’s Xinhua News Agency released the news.-- Combining with Hangcuo Lake, a National Natural Reserve and Scenic in Tibet, to plan and establish the Dark Sky Park.-- Cooperated with Shandong Longgang Tourism Group to construct the Dream Sky Theme Park in the suburbs of Jinan city.In the IYL 2015, the SSPC is getting further development:First, make dark sky protection enter National Ecological Strategy of “Beautiful China”. We call on: “Beautiful China” needs “Beautiful Night Sky” China should care the shared starry sky, and left this resource and heritage for children.Second, hold “Cosmic Light” exhibition in Shanghai Science and Technology Museum on August.Third, continue to establish Dark Sky Reserve, Park and Theme Park. We want to make these places become the bases of dark sky protection, astronomical education and ecological tourism, and develop into new cultural industry.Fourth, actively join international cooperation.Now, “Blue Sky, White Cloud and Starry Sky “have become

Tropospheric haze and colors of the clear daytime sky.

PubMed

Lee, Raymond L

2015-02-01

To casual observers, haze's visible effects on clear daytime skies may seem mundane: significant scattering by tropospheric aerosols visibly (1) reduces the luminance contrast of distant objects and (2) desaturates sky blueness. However, few published measurements of hazy-sky spectra and chromaticities exist to compare with these naked-eye observations. Hyperspectral imaging along sky meridians of clear and hazy skies at one inland and two coastal sites shows that they have characteristic colorimetric signatures of scattering and absorption by haze aerosols. In addition, a simple spectral transfer function and a second-order scattering model of skylight reveal the net spectral and colorimetric effects of haze.

Aquarius L-Band Radiometers Calibration Using Cold Sky Observations

NASA Technical Reports Server (NTRS)

Dinnat, Emmanuel P.; Le Vine, David M.; Piepmeier, Jeffrey R.; Brown, Shannon T.; Hong, Liang

2015-01-01

An important element in the calibration plan for the Aquarius radiometers is to look at the cold sky. This involves rotating the satellite 180 degrees from its nominal Earth viewing configuration to point the main beams at the celestial sky. At L-band, the cold sky provides a stable, well-characterized scene to be used as a calibration reference. This paper describes the cold sky calibration for Aquarius and how it is used as part of the absolute calibration. Cold sky observations helped establish the radiometer bias, by correcting for an error in the spillover lobe of the antenna pattern, and monitor the long-term radiometer drift.

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.

Evaluation of Clear Sky Models for Satellite-Based Irradiance Estimates

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

Sengupta, Manajit; Gotseff, Peter

2013-12-01

This report describes an intercomparison of three popular broadband clear sky solar irradiance model results with measured data, as well as satellite-based model clear sky results compared to measured clear sky data. The authors conclude that one of the popular clear sky models (the Bird clear sky model developed by Richard Bird and Roland Hulstrom) could serve as a more accurate replacement for current satellite-model clear sky estimations. Additionally, the analysis of the model results with respect to model input parameters indicates that rather than climatological, annual, or monthly mean input data, higher-time-resolution input parameters improve the general clear skymore » model performance.« less

Spectral karyotyping (SKY) in hematological neoplasia

NASA Astrophysics Data System (ADS)

Preiss, Birgitte S.; Pedersen, Rikke K.; Kerndrup, Gitte B.

2001-07-01

From November 1, 1997 till November 1, 2000 we have investigated 204 cases of acute myeloid leukemia (AML) (nequals95), acute lymphatic leukemia (ALL) (nequals40), myelodysplastic syndrome (MDS) (nequals11), chronic myeloid leukemia (CML) (nequals9), chronic lymphatic leukemia (CLL) (nequals4) and non-Hodgkin lymphoma (NHL) (nequals45) cytogenetically, using G-band analysis and spectral karyotyping (SKY). By SKY we were able to detect the abnormal clones in all cases but 9. In the G-band preparations these cases showed very few abnormal mitoses. The SKY either extended or confirmed the G-band findings in 94% of those with an abnormal karyotype. Cryptic translocations (translocations not suspected from the G-band karyotype) were found in 71 cases (26 AML, 9 ALL, 5 MDS, 2 CLL and 29 NHL). We find SKY a powerful adjuvant diagnostic tool that does not compromise one of the advantages of karyotyping techniques, the analysis of the entire genome which, in contrast to molecular biological techniques, still leave the possibility to get mroe answers than questions posed.

Educational Research and Evidence-Based Policy: The Mixed-Method Approach of the EPPE Project

ERIC Educational Resources Information Center

Siraj-Blatchford, I.

2006-01-01

In a review of the challenges to progress in providing social research evidence that might usefully inform policy, Oakley (2004) argues strongly that the "paradigm divide" between qualitative and quantitative research communities continues to constitute a major problem. Oakley refers to a number of recent critiques of what is seen as "misplaced…

THE FIRST COMBINED SEARCH FOR NEUTRINO POINT-SOURCES IN THE SOUTHERN HEMISPHERE WITH THE ANTARES AND ICECUBE NEUTRINO TELESCOPES

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

Adrián-Martínez, S.; Ardid, M.; Albert, A.

2016-05-20

We present the results of searches for point-like sources of neutrinos based on the first combined analysis of data from both the ANTARES and IceCube neutrino telescopes. The combination of both detectors, which differ in size and location, forms a window in the southern sky where the sensitivity to point sources improves by up to a factor of 2 compared with individual analyses. Using data recorded by ANTARES from 2007 to 2012, and by IceCube from 2008 to 2011, we search for sources of neutrino emission both across the southern sky and from a preselected list of candidate objects. Nomore » significant excess over background has been found in these searches, and flux upper limits for the candidate sources are presented for E {sup −2.5} and E {sup −2} power-law spectra with different energy cut-offs.« less

SKYMONITOR: A Global Network for Sky Brightness Measurements

NASA Astrophysics Data System (ADS)

Davis, Donald R.; Mckenna, D.; Pulvermacher, R.; Everett, M.

2010-01-01

We are implementing a global network to measure sky brightness at dark-sky critical sites with the goal of creating a multi-decade database. The heart of this project is the Night Sky Brightness Monitor (NSBM), an autonomous 2 channel photometer which measures night sky brightness in the visual wavelengths (Mckenna et al, AAS 2009). Sky brightness is measured every minute at two elevation angles typically zenith and 20 degrees to monitor brightness and transparency. The NSBM consists of two parts, a remote unit and a base station with an internet connection. Currently these devices use 2.4 Ghz transceivers with a range of 100 meters. The remote unit is battery powered with daytime recharging using a solar panel. Data received by the base unit is transmitted via email protocol to IDA offices in Tucson where it will be collected, archived and made available to the user community via a web interface. Two other versions of the NSBM are under development: one for radio sensitive areas using an optical fiber link and the second that reads data directly to a laptop for sites without internet access. NSBM units are currently undergoing field testing at two observatories. With support from the National Science Foundation, we will construct and install a total of 10 units at astronomical observatories. With additional funding, we will locate additional units at other sites such as National Parks, dark-sky preserves and other sites where dark sky preservation is crucial. We will present the current comparison with the National Park Service sky monitoring camera. We anticipate that the SKYMONITOR network will be functioning by the end of 2010.

PySM: Python Sky Model

NASA Astrophysics Data System (ADS)

Thorne, Ben; Alonso, David; Naess, Sigurd; Dunkley, Jo

2017-04-01

PySM generates full-sky simulations of Galactic foregrounds in intensity and polarization relevant for CMB experiments. The components simulated are thermal dust, synchrotron, AME, free-free, and CMB at a given Nside, with an option to integrate over a top hat bandpass, to add white instrument noise, and to smooth with a given beam. PySM is based on the large-scale Galactic part of Planck Sky Model code and uses some of its inputs

Indoor calibration of Sky Quality Meters: Linearity, spectral responsivity and uncertainty analysis

NASA Astrophysics Data System (ADS)

Pravettoni, M.; Strepparava, D.; Cereghetti, N.; Klett, S.; Andretta, M.; Steiger, M.

2016-09-01

The indoor calibration of brightness sensors requires extremely low values of irradiance in the most accurate and reproducible way. In this work the testing equipment of an ISO 17025 accredited laboratory for electrical testing, qualification and type approval of solar photovoltaic modules was modified in order to test the linearity of the instruments from few mW/cm2 down to fractions of nW/cm2, corresponding to levels of simulated brightness from 6 to 19 mag/arcsec2. Sixteen Sky Quality Meter (SQM) produced by Unihedron, a Canadian manufacturer, were tested, also assessing the impact of the ageing of their protective glasses on the calibration coefficients and the drift of the instruments. The instruments are in operation on measurement points and observatories at different sites and altitudes in Southern Switzerland, within the framework of OASI, the Environmental Observatory of Southern Switzerland. The authors present the results of the calibration campaign: linearity; brightness calibration, with and without protective glasses; transmittance measurement of the glasses; and spectral responsivity of the devices. A detailed uncertainty analysis is also provided, according to the ISO 17025 standard.

An Innovative Collaboration on Dark Skies Education

NASA Astrophysics Data System (ADS)

Walker, Constance E.; Mayer, M.; EPO Students, NOAO

2011-01-01

Dark night skies are being lost all over the globe, and hundreds of millions of dollars of energy are being wasted in the process.. Improper lighting is the main cause of light pollution. Light pollution is a concern on many fronts, affecting safety, energy conservation, cost, human health, and wildlife. It also robs us of the beauty of viewing the night sky. In the U.S. alone, over half of the population cannot see the Milky Way from where they live. To help address this, the National Optical Astronomy Observatory Education and Public Outreach (NOAO EPO) staff created two programs: Dark Skies Rangers and GLOBE at Night. Through the two programs, students learn about the importance of dark skies and experience activities that illustrate proper lighting, light pollution's effects on wildlife and how to measure the darkness of their skies. To disseminate the programs locally in an appropriate yet innovative venue, NOAO partnered with the Cooper Center for Environmental Learning in Tucson, Arizona. Operated by the largest school district in Tucson and the University of Arizona College of Education, the Cooper Center educates thousands of students and educators each year about ecology, science, and the beauty and wonders of the Sonoran Desert. During the first academic year (2009-2010), we achieved our goal of reaching nearly 20 teachers in 40 classrooms of 1000 students. We gave two 3-hour teacher-training sessions and provided nineteen 2.5-hour on-site evening sessions on dark skies activities for the students of the teachers trained. One outcome of the program was the contribution of 1000 "GLOBE at Night 2010” night-sky brightness measurements by Tucson students. Training sessions at similar levels are continuing this year. The partnership, planning, lesson learned, and outcomes of NOAO's collaboration with the environmental center will be presented.

Moon night sky brightness simulation for the Xinglong station

NASA Astrophysics Data System (ADS)

Yao, Song; Zhang, Hao-Tong; Yuan, Hai-Long; Zhao, Yong-Heng; Dong, Yi-Qiao; Bai, Zhong-Rui; Deng, Li-Cai; Lei, Ya-Juan

2013-10-01

Using a sky brightness monitor at the Xinglong station of National Astronomical Observatories, Chinese Academy of Sciences, we collected data from 22 dark clear nights and 90 moon nights. We first measured the sky brightness variation with time for dark nights and found a clear correlation between sky brightness and human activity. Then with a modified sky brightness model of moon nights and data from these nights, we derived the typical value for several important parameters in the model. With these results, we calculated the sky brightness distribution under a given moon condition for the Xinglong station. Furthermore, we simulated the sky brightness distribution of a moon night for a telescope with a 5° field of view (such as LAMOST). These simulations will be helpful for determining the limiting magnitude and exposure time, as well as planning the survey for LAMOST during moon nights.

On-Orbit Sky Background Measurements with the FOS

NASA Technical Reports Server (NTRS)

Lyons, R. W.; Baity, W. A.; Beaver, E. A.; Cohen, R. D.; Junkkarinen, V. T.; Linsky, J. B.; Bohlin, R. C.

1993-01-01

Observations of the sky background obtained with the Faint Object Spectrograph during 1991-1992 are discussed. Sky light can be an important contributor to the observed count rate in several of the instrument configurations especially when large apertures are used. In general, the sky background is consistent with the pre-launch expectations and showed the expected effects of zodiacal light and diffuse galactic light. In addition to these sources, there is, particularly during the daytime, a highly variable airglow component which includes a number of emission lines. The sky background will have an impact on the reduction and possibly the interpretation of some spectra.

Photosynthetically active sunlight at high southern latitudes.

PubMed

Frederick, John E; Liao, Yixiang

2005-01-01

A network of scanning spectroradiometers has acquired a multiyear database of visible solar irradiance, covering wavelengths from 400 to 600 nm, at four sites in the high-latitude Southern Hemisphere, from 55 degrees S to 90 degrees S. Monthly irradiations computed from the hourly measurements reveal the character of the seasonal cycle and illustrate the role of cloudiness as functions of latitude. Near summer solstice, the combined influences of solar elevation and the duration of daylight would produce a monthly irradiation with little latitude dependence under clear skies. However, the attenuation associated with local cloudiness varies geographically, with the greatest effect at the most northern locations, Ushuaia, Argentina and Palmer Station on the Antarctic Peninsula. Near summer solstice, the South Pole experiences the largest monthly irradiation of the sites studied, where relatively clear skies contribute to this result. Scaling factors derived from radiative-transfer calculations combined with the measured 400-600 nm irradiances allow estimating irradiances integrated over the wavelength band 400-700 nm. This produces a climatology of photosynthetically active radiation for each month of the year at each site.

The Two Micron All Sky Survey

NASA Technical Reports Server (NTRS)

Kleinmann, S. G.; Lysaght, M. G.; Pughe, W. L.; Schneider, S. E.; Skrutskie, M. F.; Weinberg, M. D.; Price, S. D.; Matthews, K.; Soifer, B. T.; Huchra, J. P.

1994-01-01

The Two Micron All Sky Survey (2MASS) will provide a uniform survey of the entire sky at three near-infrared wavebands: J(lambda(sub eff) = 1.25 micrometers), H(lambda(sub eff) = 1.65 micrometers), and K(sub s)(lambda(sub eff) = 2.16 micrometers). A major goal of the survey is to probe large scale structures in the Milky Way and in the Local Universe, exploiting the relatively high transparency of the interstellar medium in the near-infrared, and the high near-infrared luminosities of evolved low- and intermediate-mass stars. A sensitive overview of the near-infrared sky is also an essential next step to maximize the gains achievable with infrared array technology. Our assessment of the astrophysical questions that might be addressed with these new arrays is currently limited by the very bright flux limit of the only preceding large scale near-infrared sky survey, the Two Micron Sky Survey carried out at Caltech in the late 1960's. Near-infrared instruments based on the new array technology have already obtained spectra of objects 1 million times fainter than the limit of the TMSS! This paper summarizes the essential parameters of the 2MASS project and the rationale behind those choices, and gives an overview of results obtained with a prototype camera that has been in operation since May 1992. We conclude with a list of expected data products and a statement of the data release policy.

Global horizontal irradiance clear sky models : implementation and analysis.

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

Stein, Joshua S.; Hansen, Clifford W.; Reno, Matthew J.

2012-03-01

Clear sky models estimate the terrestrial solar radiation under a cloudless sky as a function of the solar elevation angle, site altitude, aerosol concentration, water vapor, and various atmospheric conditions. This report provides an overview of a number of global horizontal irradiance (GHI) clear sky models from very simple to complex. Validation of clear-sky models requires comparison of model results to measured irradiance during clear-sky periods. To facilitate validation, we present a new algorithm for automatically identifying clear-sky periods in a time series of GHI measurements. We evaluate the performance of selected clear-sky models using measured data from 30 differentmore » sites, totaling about 300 site-years of data. We analyze the variation of these errors across time and location. In terms of error averaged over all locations and times, we found that complex models that correctly account for all the atmospheric parameters are slightly more accurate than other models, but, primarily at low elevations, comparable accuracy can be obtained from some simpler models. However, simpler models often exhibit errors that vary with time of day and season, whereas the errors for complex models vary less over time.« less

How the clear-sky angle of polarization pattern continues underneath clouds: full-sky measurements and implications for animal orientation.

PubMed

Pomozi, I; Horváth, G; Wehner, R

2001-09-01

One of the biologically most important parameters of the cloudy sky is the proportion P of the celestial polarization pattern available for use in animal navigation. We evaluated this parameter by measuring the polarization patterns of clear and cloudy skies using 180 degrees (full-sky) imaging polarimetry in the red (650 nm), green (550 nm) and blue (450 nm) ranges of the spectrum under clear and partly cloudy conditions. The resulting data were compared with the corresponding celestial polarization patterns calculated using the single-scattering Rayleigh model. We show convincingly that the pattern of the angle of polarization (e-vectors) in a clear sky continues underneath clouds if regions of the clouds and parts of the airspace between the clouds and the earth surface (being shady at the position of the observer) are directly lit by the sun. The scattering and polarization of direct sunlight on the cloud particles and in the air columns underneath the clouds result in the same e-vector pattern as that present in clear sky. This phenomenon can be exploited for animal navigation if the degree of polarization is higher than the perceptual threshold of the visual system, because the angle rather than the degree of polarization is the most important optical cue used in the polarization compass. Hence, the clouds reduce the extent of sky polarization pattern that is useful for animal orientation much less than has hitherto been assumed. We further demonstrate quantitatively that the shorter the wavelength, the greater the proportion of celestial polarization that can be used by animals under cloudy-sky conditions. As has already been suggested by others, this phenomenon may solve the ultraviolet paradox of polarization vision in insects such as hymenopterans and dipterans. The present study extends previous findings by using the technique of 180 degrees imaging polarimetry to measure and analyse celestial polarization patterns.

Touch the Cosmos: The 2012 International Earth and Sky Photo Contest

NASA Astrophysics Data System (ADS)

Walker, C. E.; Tafreshi, B.; Simmons, M.

2013-04-01

In April 2012, the National Optical Astronomy Observatory in partnership with The World At Night organized the Third International Earth and Sky Photo Contest on the importance of preserving dark skies for the Dark Skies Awareness theme of Global Astronomy Month. At the Fall 2012 ASP conference, a presentation on the Earth and Sky Photo Contest was made. The intended outcomes of the 10-minute oral talk were 1) to inspire visual learners to be more aware of the disappearing starry night sky due to light pollution, 2) to provide some basic understanding of what the issues are surrounding light pollution, 3) to provide incentive to get people to participate in the photo contest as a way of promoting dark skies awareness and 4) to provide a stepping stone to more active involvement in dark skies preservation. With more than half of the world's population in cities, Earth and Sky photos of dark, starry skies offer the next best thing to being there.

Tracing the properties of the Sagittarius stream across the sky with LAMOST spectra

NASA Astrophysics Data System (ADS)

Walder, Madison Victoria; Carlin, Jeffrey

2018-01-01

The Sagittarius dwarf galaxy is a satellite that is currently being consumed by the Milky Way’s gravity. Its disruption has created the most prominent and widely studied tidal stream in our halo which wraps around our Galaxy with its leading arm in the northern Galactic hemisphere and its trailing arm in the southern hemisphere. Using optical spectra collected by the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) survey, we identify stars that belong to the Sagittarius tidal stream based on their positions, distances, velocities, stellar parameters, and metallicities. We trace the velocity, metallicity, and distance of the Sagittarius stream over 200 degrees of its extent on the sky using a homogenous spectroscopic data set. In doing this, we will be able to trace the stream in regions where the disk of the Galaxy makes it difficult to distinguish Sagittarius members from the far more numerous foreground stars, and therefore use the entirety of the stream to deepen our understanding of tidal disruption. We use the spectroscopic metallicities from LAMOST to derive the metallicity as a function of position along the stream, providing an important probe of the ongoing process of tidal disruption, and a window into the stellar populations that made up the Sagittarius dwarf before its cannibalization by the Milky Way.

Armenian Names of Sky Constellations

NASA Astrophysics Data System (ADS)

Mickaelian, A. M.; Farmanyan, S. V.; Mikayelyan, A. A.

2016-12-01

The work is devoted to the correction and recovery of the Armenian names of the sky constellations, as they were forgotten or distorted during the Soviet years, mainly due to the translation from Russian. A total of 34 constellation names have been corrected. A brief overview of the history of the division of the sky into constellations and their naming is also given. At the end, the list of all 88 constellations is given with the names in Latin, English, Russian and Armenian.

Fading Skies

ERIC Educational Resources Information Center

Sio, Betsy Menson

2009-01-01

A sky fading from blue to white to red at the horizon, and water darkening from light to midnight blue. Strong diagonals slashing through the image, drawing a viewer's eyes deeper into the picture, and delicate trees poised to convey a sense of beauty. These are the fascinating strengths of the ukiyo-e woodblock prints of Japanese artist Ando…

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/.

The LWA1 Low Frequency Sky Survey

NASA Astrophysics Data System (ADS)

Dowell, Jayce; Taylor, Gregory B.; LWA Collaboration

2015-01-01

The LWA1 Low Frequency Sky Survey is a survey of the sky visible from the first station of the Long Wavelength Array (LWA1) across the frequency range of 35 to 80 MHz. The primary motivation behind this effort is to improve our understanding of the sky at these frequencies. In particular, an understanding of the low frequency foreground emission is necessary for work on detecting the epoch of reionization and the cosmic dark ages where the foreground signal dwarfs the expected redshifted HI signal by many orders of magnitude (Pritchard & Loeb 2012, Rep. Prog. Phys., 75, 086901). The leading model for the sky in the frequency range of 20 to 200 MHz is the Global Sky Model (GSM) by de Oliveria-Costas et al. (2008, MNRAS, 288, 247). This model is based upon a principle component analysis of 11 sky maps ranging in frequency from 10 MHz to 94 GHz. Of these 11 maps, only four are below 1 GHz; 10 MHz from Caswell (1976, MNRAS, 177, 601), 22 MHz from Roger et al. (1999, A&AS, 137, 7), 45 MHz from Alvarez et al. (1997, A&AS, 124, 315) and Maeda et al. (1999, A&AS, 140, 145), and 408 MHz from Haslam et al. (1982, A&AS, 47, 1). Thus, within this model, the region of interest to both cosmic dawn and the epoch of reionization is largely unconstrained based on the available survey data, and are also limited in terms of the spatial coverage and calibration. A self-consistent collection of maps is necessary for both our understanding of the sky and the removal of the foregrounds that mask the redshifted 21-cm signal.We present the current state of the survey and discuss the imaging and calibration challenges faced by dipole arrays that are capable of imaging nearly 2π steradians of sky simultaneously over a large fractional bandwidth.Construction of the LWA has been supported by the Office of Naval Research under Contract N00014-07-C-0147. Support for operations and continuing development of the LWA1 is provided by the National Science Foundation under grants AST-1139963 and AST

Dark Skies Rangers

NASA Astrophysics Data System (ADS)

Doran, Rosa

2015-08-01

Creating awareness about the importance of the protection of our dark skies is the main goal of the Dark Skies Rangers project, a joint effort from the NOAO and the Galileo Teacher Training Program. Hundreds of schools and thousands of students have been reached by this program. We will focus in particular on the experience being developed in Portugal where several municipalities have now received street light auditing produced by students with suggestions on how to enhance the energy efficiency of illumination of specific urban areas. In the International Year of Light we are investing our efforts in exporting the successful Portuguese experience to other countries. The recipe is simple: train teachers, engage students, foster the participation of local community and involve local authorities in the process. In this symposium we hope to draft the cookbook for the near future.

Daytime Sky Brightness Characterization for Persistent GEO SSA

NASA Astrophysics Data System (ADS)

Thomas, G.; Cobb, R. G.

Space Situational Awareness (SSA) is fundamental to operating in space. SSA for collision avoidance ensures safety of flight for both government and commercial spacecraft through persistent monitoring. A worldwide network of optical and radar sensors gather satellite ephemeris data from the nighttime sky. Current practice for daytime satellite tracking is limited exclusively to radar as the brightening daytime sky prevents the use of visible-band optical sensors. Radar coverage is not pervasive and results in significant daytime coverage gaps in SSA. To mitigate these gaps, optical telescopes equipped with sensors in the near-infrared band (0.75-0.9m) may be used. The diminished intensity of the background sky radiance in the near-infrared band may allow for daylight tracking further into the twilight hours. To determine the performance of a near-infrared sensor for daylight custody, the sky background radiance must first be characterized spectrally as a function of wavelength. Using a physics-based atmospheric model with access to near-real time weather, we developed a generalized model for the apparent sky brightness of the Geostationary satellite belt. The model results are then compared to measured data collected from Dayton, OH through various look and Sun angles for model validation and spectral sky radiance quantification in the visible and near-infrared bands.

The Catalina Sky Survey for Near-Earth Objects

NASA Astrophysics Data System (ADS)

Christensen, E.

The Catalina Sky Survey (CSS) specializes in the detection of the closest transients in our transient universe: near-Earth objects (NEOs). CSS is the leading NEO survey program since 2005, with a discovery rate of 500-600 NEOs per year. This rate is set to substantially increase starting in 2014 with the deployment of wider FOV cameras at both survey telescopes, while a proposed 3-telescope system in Chile would provide a new and significant capability in the Southern Hemisphere beginning as early as 2015. Elements contributing to the success of CSS may be applied to other surveys, and include 1) Real-time processing, identification, and reporting of interesting transients; 2) Human-assisted validation to ensure a clean transient stream that is efficient to the limits of the system (˜ 1σ); 3) an integrated follow-up capability to ensure threshold or high-priority transients are properly confirmed and followed up. Additionally, the open-source nature of the CSS data enables considerable secondary science (i.e. CRTS), and CSS continues to pursue collaborations to maximize the utility of the data.

The Solar Neighborhood. 35. Distances to 1404 M Dwarf Systems Within 25 PC in the Southern Sky

DTIC Science & Technology

2015-01-01

reference, and 2MASS JHKs magnitudes. The table is divided into the 1404 systems within 25 pc (top) and the 344 systems beyond 25 pc (bottom). A number in... 2MASS JHKs magnitudes, as discussed in Section 4.1. The plate R59F magnitude is the second, more recent R epoch measurement of the two available in...the SuperCOSMOS Sky Survey. The term ccddist is used to indicate a distance estimate that combines CCD VRI and 2MASS JHKs magnitudes, as discussed in

Sky type discrimination using a ground-based sun photometer

USGS Publications Warehouse

DeFelice, Thomas P.; Wylie, Bruce K.

2001-01-01

A 2-year feasibility study was conducted at the USGS EROS Data Center, South Dakota (43.733°N, 96.6167°W) to assess whether a four-band, ground-based, sun photometer could be used to discriminate sky types. The results indicate that unique spectral signatures do exist between sunny skies (including clear and hazy skies) and cirrus, and cirrostratus, altocumulus or fair-weather cumulus, and thin stratocumulus or altostratus, and fog/fractostratus skies. There were insufficient data points to represent other cloud types at a statistically significant level.

An Initial Meteoroid Stream Survey in the Southern Hemisphere Using the Southern Argentina Agile Meteor Radar (SAAMER)

NASA Technical Reports Server (NTRS)

Janches, D.; Hormaechea, J. L.; Brunini, C.; Hocking, W.; Fritts, D. C.

2013-01-01

We present in this manuscript a 4 year survey of meteor shower radiants utilizing the Southern Argentina Agile Meteor Radar (SAAMER). SAAMER, which operates at the southern most region of South America, is a new generation SKiYMET system designed with significant differences from typical meteor radars including high transmitted power and an 8-antenna transmitting array enabling large detected rates at low zenith angles. We applied the statistical methodology developed by Jones and Jones (Jones, J., Jones, W. [2006]. Month. Not. R. Astron. Soc. 367, 1050-1056) to the data collected each day and compiled the results into 1 composite representative year at 1 resolution in Solar Longitude. We then search for enhancements in the activity which last for at least 3 days and evolve temporally as is expected from a meteor shower. Using this methodology, we have identified in our data 32 shower radiants, two of which were not part of the IAU commission 22 meteor shower working list. Recently, SAAMER's capabilities were enhanced by adding two remote stations to receive meteor forward scatter signals from meteor trails and thus enable the determination of meteoroid orbital parameters. SAAMER started recording orbits in January 2012 and future surveys will focus on the search for unknown meteor streams, in particular in the southern ecliptic sky.

SkyNet: A Modular Nuclear Reaction Network Library

NASA Astrophysics Data System (ADS)

Lippuner, Jonas; Roberts, Luke F.

2017-12-01

Almost all of the elements heavier than hydrogen that are present in our solar system were produced by nuclear burning processes either in the early universe or at some point in the life cycle of stars. In all of these environments, there are dozens to thousands of nuclear species that interact with each other to produce successively heavier elements. In this paper, we present SkyNet, a new general-purpose nuclear reaction network that evolves the abundances of nuclear species under the influence of nuclear reactions. SkyNet can be used to compute the nucleosynthesis evolution in all astrophysical scenarios where nucleosynthesis occurs. SkyNet is free and open source, and aims to be easy to use and flexible. Any list of isotopes can be evolved, and SkyNet supports different types of nuclear reactions. SkyNet is modular so that new or existing physics, like nuclear reactions or equations of state, can easily be added or modified. Here, we present in detail the physics implemented in SkyNet with a focus on a self-consistent transition to and from nuclear statistical equilibrium to non-equilibrium nuclear burning, our implementation of electron screening, and coupling of the network to an equation of state. We also present comprehensive code tests and comparisons with existing nuclear reaction networks. We find that SkyNet agrees with published results and other codes to an accuracy of a few percent. Discrepancies, where they exist, can be traced to differences in the physics implementations.

The Sky This Week, 2016 April 19 - 26 - Naval Oceanography Portal

Science.gov Websites

are here: Home › USNO › News, Tours & Events › Sky This Week › The Sky This Week, 2016 April 19 - 26 USNO Logo USNO Navigation Tour Information USNO Scientific Colloquia Sky This Week The Sky This Week, 2016 April 19 - 26 Info The Sky This Week, 2016 April 19 - 26 A bright and speedy star

The Sky This Week, 2015 December 8 - 15 - Naval Oceanography Portal

Science.gov Websites

are here: Home › USNO › News, Tours & Events › Sky This Week › The Sky This Week, 2015 December 8 - 15 USNO Logo USNO Navigation Tour Information USNO Scientific Colloquia Sky This Week The Sky This Week, 2015 December 8 - 15 Info The Sky This Week, 2015 December 8 - 15 The year's best meteor

Weather and atmosphere observation with the ATOM all-sky camera

NASA Astrophysics Data System (ADS)

Jankowsky, Felix; Wagner, Stefan

2015-03-01

The Automatic Telescope for Optical Monitoring (ATOM) for H.E.S.S. is an 75 cm optical telescope which operates fully automated. As there is no observer present during observation, an auxiliary all-sky camera serves as weather monitoring system. This device takes an all-sky image of the whole sky every three minutes. The gathered data then undergoes live-analysis by performing astrometric comparison with a theoretical night sky model, interpreting the absence of stars as cloud coverage. The sky monitor also serves as tool for a meteorological analysis of the observation site of the the upcoming Cherenkov Telescope Array. This overview covers design and benefits of the all-sky camera and additionally gives an introduction into current efforts to integrate the device into the atmosphere analysis programme of H.E.S.S.

Optical infrared sky survey

NASA Technical Reports Server (NTRS)

Craine, E. R.

1978-01-01

A description is presented of a photographic survey of the northern sky currently underway at Steward Observatory. The survey is being conducted at a principal bandpass of 8000-9000 A supplemented by a V bandpass. The survey is the first of its type conducted using a small (20-in. aperture) wide-field telescope, a very large-format (146 mm) image intensifier with a red-extended, multialkali photocathode. The output phosphor of the intensifier is photographed with IIaD emulsion on film. One of the goals of the survey is to catalog red stellar objects on the photographs and to examine in detail regions of the sky which are obscured by hydrogen emission on conventional photographs.

Build YOUR All-Sky View with Aladin

NASA Astrophysics Data System (ADS)

Oberto, A.; Fernique, P.; Boch, T.; Bonnarel, F.

2011-07-01

From the need to extend the display outside the boundaries of a single image, the Aladin team recently developed a new feature to visualize wide areas or even all of the sky. This all-sky view is particularly useful for visualization of very large objects and, with coverage of the whole sky, maps from the Planck satellite. To improve on this capability, some catalogs and maps have been built from many surveys (e.g., DSS, IRIS, GLIMPSE, SDSS, 2MASS) in mixed resolutions, allowing progressive display. The maps are constructed by mosaicing individual images. Now, we provide a new tool to build an all-sky view with your own images. From the images you have selected, it will compose a mosaic with several resolutions (HEALPix tessellation), and organize them to allow their progressive display in Aladin. For convenience, you can export it to a HEALPix map, or share it with the community through Aladin from your web site or eventually from the CDS image collection.

All-Sky Microwave Imager Data Assimilation at NASA GMAO

NASA Technical Reports Server (NTRS)

Kim, Min-Jeong; Jin, Jianjun; El Akkraoui, Amal; McCarty, Will; Todling, Ricardo; Gu, Wei; Gelaro, Ron

2017-01-01

Efforts in all-sky satellite data assimilation at the Global Modeling and Assimilation Office (GMAO) at NASA Goddard Space Flight Center have been focused on the development of GSI configurations to assimilate all-sky data from microwave imagers such as the GPM Microwave Imager (GMI) and Global Change Observation Mission-Water (GCOM-W) Advanced Microwave Scanning Radiometer 2 (AMSR-2). Electromagnetic characteristics associated with their wavelengths allow microwave imager data to be relatively transparent to atmospheric gases and thin ice clouds, and highly sensitive to precipitation. Therefore, GMAOs all-sky data assimilation efforts are primarily focused on utilizing these data in precipitating regions. The all-sky framework being tested at GMAO employs the GSI in a hybrid 4D-EnVar configuration of the Goddard Earth Observing System (GEOS) data assimilation system, which will be included in the next formal update of GEOS. This article provides an overview of the development of all-sky radiance assimilation in GEOS, including some performance metrics. In addition, various projects underway at GMAO designed to enhance the all-sky implementation will be introduced.

The Sky This Week, 2016 March 15 - 23 - Naval Oceanography Portal

Science.gov Websites

are here: Home › USNO › News, Tours & Events › Sky This Week › The Sky This Week, 2016 March 15 - 23 USNO Logo USNO Navigation Tour Information USNO Scientific Colloquia Sky This Week The Sky This Week, 2016 March 15 - 23 Info The Sky This Week, 2016 March 15 - 23 The equinox and the calendar

The Sky This Week, 2016 January 19 - 26 - Naval Oceanography Portal

Science.gov Websites

are here: Home › USNO › News, Tours & Events › Sky This Week › The Sky This Week, 2016 January 19 - 26 USNO Logo USNO Navigation Tour Information USNO Scientific Colloquia Sky This Week The Sky This Week, 2016 January 19 - 26 Info The Sky This Week, 2016 January 19 - 26 See all the bright planets

The Sky This Week, 2016 January 5 - 12 - Naval Oceanography Portal

Science.gov Websites

are here: Home › USNO › News, Tours & Events › Sky This Week › The Sky This Week, 2016 January 5 - 12 USNO Logo USNO Navigation Tour Information USNO Scientific Colloquia Sky This Week The Sky This Week, 2016 January 5 - 12 Info The Sky This Week, 2016 January 5 - 12 Count the stars in Orion for

Northern Sky Galactic Cosmic Ray Anisotropy between 10 and 1000 TeV with the Tibet Air Shower Array

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

Amenomori, M.; Bi, X. J.; Chen, W. Y.

2017-02-20

We report on the analysis of the 10–1000 TeV large-scale sidereal anisotropy of Galactic cosmic rays (GCRs) with the data collected by the Tibet Air Shower Array from 1995 October to 2010 February. In this analysis, we improve the energy estimate and extend the decl. range down to −30°. We find that the anisotropy maps above 100 TeV are distinct from that at a multi-TeV band. The so-called tail-in and loss-cone features identified at low energies get less significant, and a new component appears at ∼100 TeV. The spatial distribution of the GCR intensity with an excess (7.2 σ pre-trial,more » 5.2 σ post-trial) and a deficit (−5.8 σ pre-trial) are observed in the 300 TeV anisotropy map, in close agreement with IceCube’s results at 400 TeV. Combining the Tibet results in the northern sky with IceCube’s results in the southern sky, we establish a full-sky picture of the anisotropy in hundreds of TeV band. We further find that the amplitude of the first order anisotropy increases sharply above ∼100 TeV, indicating a new component of the anisotropy. All these results may shed new light on understanding the origin and propagation of GCRs.« less

Sub-millimetre Astronomy in Full Swing on Southern Skies

NASA Astrophysics Data System (ADS)

2006-07-01

the superb efficiency of APEX. Light coming from a charged molecule composed of Hydrogen and Deuterium (H2D+) was detected in several cold clouds in the Southern Sky. The H2D+ ion is interesting because it traces gas so cold (a few degrees above the absolute zero!) that only a few molecular species have not frozen out onto the surfaces of dust grains. These are not the only significant discoveries made. Other highlights include the first observations of atomic carbon in the so-called "Pillars of Creation" in the Eagle Nebula (also known as Messier 16), a sub-millimetre study of a massive hot core, of a high-mass star forming region, as well as of a high velocity outflow coming from a young stellar object. Studies of molecular regions in the dwarf galaxy NGC 6822 and in the starburst galaxy NGC 253 were also done, proving that APEX can also contribute to the exploration of extragalactic objects. Apart from the astronomical studies, a series of contributions deal with the technical aspects of APEX, such as the telescope itself, its software, its receivers and spectrometers. The latter were developed at the Max-Planck-Institut für Radioastronomie in Bonn, Germany and at the Swedish Chalmers University, while the 0.2 mm receiver was developed at the University of Cologne (Germany). ESO PR Photo 24b/06 ESO PR Photo 24b/06 APEX at Chajnantor The APEX telescope, designed to work at sub-millimetre wavelengths, in the 0.2 to 1.5 mm range, passed successfully its Science Verification phase in July 2005 (see ESO PR 18/05 and ESO PR 25/05), and since then is performing regular science observations. It is located on the 5100 m high Chajnantor plateau in the Atacama Desert (Chile), probably the driest place on Earth. It is a collaborative effort between the Max-Planck-Institut für Radioastronomie, ESO and the Onsala Space Observatory (Sweden). With its precise antenna and large collecting area, APEX provides, at this exceptional location, unprecedented access to a whole new

Night Sky Brightness at San Pedro Martir Observatory

NASA Astrophysics Data System (ADS)

Plauchu-Frayn, I.; Richer, M. G.; Colorado, E.; Herrera, J.; Córdova, A.; Ceseña, U.; Ávila, F.

2017-03-01

We present optical UBVRI zenith night sky brightness measurements collected on 18 nights during 2013 to 2016 and SQM measurements obtained daily over 20 months during 2014 to 2016 at the Observatorio Astronómico Nacional on the Sierra San Pedro Mártir (OAN-SPM) in México. The UBVRI data is based upon CCD images obtained with the 0.84 m and 2.12 m telescopes, while the SQM data is obtained with a high-sensitivity, low-cost photometer. The typical moonless night sky brightness at zenith averaged over the whole period is U = 22.68, B = 23.10, V = 21.84, R = 21.04, I = 19.36, and SQM = 21.88 {mag} {{arcsec}}-2, once corrected for zodiacal light. We find no seasonal variation of the night sky brightness measured with the SQM. The typical night sky brightness values found at OAN-SPM are similar to those reported for other astronomical dark sites at a similar phase of the solar cycle. We find a trend of decreasing night sky brightness with decreasing solar activity during period of the observations. This trend implies that the sky has become darker by Δ U = 0.7, Δ B = 0.5, Δ V = 0.3, Δ R=0.5 mag arcsec-2 since early 2014 due to the present solar cycle.

The Sky This Week, 2016 January 27 - February 2 - Naval Oceanography

Science.gov Websites

Oceanography Ice You are here: Home › USNO › News, Tours & Events › Sky This Week › The Sky This Sky This Week The Sky This Week, 2016 January 27 - February 2 Info The Sky This Week, 2016 January 27 - February 2 Lest we forget. NOFS_Winter_2016_01small.jpg Dome of the Kaj Strand 1.55-meter (61-inch

Dark Sky Scotland

NASA Astrophysics Data System (ADS)

Hillier, D.

2008-06-01

Dark Sky Scotland (DSS) 2006-2008 is a nationwide programme of public and educational astronomy events. It demonstrates successful national partnerships with non-astronomy organisations and effective ways of delivering events in remote rural communities. DSS is looking for international partners for IYA2009.

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.

Astronomy Education Under Dark Skies

NASA Astrophysics Data System (ADS)

Cecylia Molenda-Zakowicz, Joanna

2015-08-01

We have been providing professional support for the high school students and the astronomy teachers since 2007. Our efforts include organizing astronomy events that take from several hours, like, e.g., watching the transit of Venus, to several days, like the workshops organized in the framework of the projects 'School Workshops on Astronomy' (SWA) and 'Wygasz'.The SWA and Wygasz workshops include presentations by experts in astronomy and space science research, presentations prepared by students being supervised by those experts, hands-on interactive experience in the amateur astrophotography, various pencil-and-paper exercises, and other practical activities. We pay particular attention to familiarize the teachers and students with the idea and the necessity of protecting the dark sky. The format of these events allows also for some time for teachers to share ideas and best practices in teaching astronomy.All those activities are organized either in the Izera Dark-Sky Park in Poland or in other carefuly selected locations in which the beauty of the dark night sky can be appreciated.

Transient Optical Sky survey

NASA Astrophysics Data System (ADS)

Hadjiyska, Elena Ivanova

2009-06-01

Optical transients have been studied in isolated cases, but never mapped into a comprehensive data base in the past. These events vary in duration and signature, yet they are united under the umbrella of time varying observables and represent a significant portion of the dynamical processes in the universe. The Transient Optical Sky Survey (TOSS) System is a dedicated, ground-based system of small optical telescopes, observing nightly at fixed Declination while gathering 90 sec exposures and thus creating a repeated partial map of the sky. Presented here is a brief overview of some of the signatures of transient events and a description of the TOSS system along with the data acquired during the 2008-2009 observing campaign, potentially producing over 100,000 light curves.

Point Source All Sky

NASA Image and Video Library

2003-03-27

This panoramic view encompasses the entire sky as seen by Two Micron All-Sky Survey. The measured brightnesses of half a billion stars (points) have been combined into colors representing three distinct wavelengths of infrared light: blue at 1.2 microns, green at 1.6 microns, and red at 2.2 microns. This image is centered on the core of our own Milky Way galaxy, toward the constellation of Sagittarius. The reddish stars seemingly hovering in the middle of the Milky Way's disc -- many of them never observed before -- trace the densest dust clouds in our galaxy. The two faint smudges seen in the lower right quadrant are our neighboring galaxies, the Small and Large Magellanic Clouds. http://photojournal.jpl.nasa.gov/catalog/PIA04250

Design of a device for sky light polarization measurements.

PubMed

Wang, Yujie; Hu, Xiaoping; Lian, Junxiang; Zhang, Lilian; Xian, Zhiwen; Ma, Tao

2014-08-14

Sky polarization patterns can be used both as indicators of atmospheric turbidity and as a sun compass for navigation. The objective of this study is to improve the precision of sky light polarization measurements by optimal design of the device used. The central part of the system is composed of a Charge Coupled Device (CCD) camera; a fish-eye lens and a linear polarizer. Algorithms for estimating parameters of the polarized light based on three images are derived and the optimal alignments of the polarizer are analyzed. The least-squares estimation is introduced for sky light polarization pattern measurement. The polarization patterns of sky light are obtained using the designed system and they follow almost the same patterns of the single-scattering Rayleigh model. Deviations of polarization angles between observation and the theory are analyzed. The largest deviations occur near the sun and anti-sun directions. Ninety percent of the deviations are less than 5° and 40% percent of them are less than 1°. The deviations decrease evidently as the degree of polarization increases. It also shows that the polarization pattern of the cloudy sky is almost identical as in the blue sky.

Design of a Device for Sky Light Polarization Measurements

PubMed Central

Wang, Yujie; Hu, Xiaoping; Lian, Junxiang; Zhang, Lilian; Xian, Zhiwen; Ma, Tao

2014-01-01

Sky polarization patterns can be used both as indicators of atmospheric turbidity and as a sun compass for navigation. The objective of this study is to improve the precision of sky light polarization measurements by optimal design of the device used. The central part of the system is composed of a Charge Coupled Device (CCD) camera; a fish-eye lens and a linear polarizer. Algorithms for estimating parameters of the polarized light based on three images are derived and the optimal alignments of the polarizer are analyzed. The least-squares estimation is introduced for sky light polarization pattern measurement. The polarization patterns of sky light are obtained using the designed system and they follow almost the same patterns of the single-scattering Rayleigh model. Deviations of polarization angles between observation and the theory are analyzed. The largest deviations occur near the sun and anti-sun directions. Ninety percent of the deviations are less than 5° and 40% percent of them are less than 1°. The deviations decrease evidently as the degree of polarization increases. It also shows that the polarization pattern of the cloudy sky is almost identical as in the blue sky. PMID:25196003

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%.

Science with the VLA Sky Survey (VLASS)

NASA Astrophysics Data System (ADS)

Murphy, Eric J.; Baum, Stefi Alison; Brandt, W. Niel; Chandler, Claire J.; Clarke, Tracy E.; Condon, James J.; Cordes, James M.; Deustua, Susana E.; Dickinson, Mark; Gugliucci, Nicole E.; Hallinan, Gregg; Hodge, Jacqueline; Lang, Cornelia C.; Law, Casey J.; Lazio, Joseph; Mao, Sui Ann; Myers, Steven T.; Osten, Rachel A.; Richards, Gordon T.; Strauss, Michael A.; White, Richard L.; Zauderer, Bevin; Extragalactic Science Working Group, Galactic Science Working Group, Transient Science Working Group

2015-01-01

The Very Large Array Sky Survey (VLASS) was initiated to develop and carry out a new generation large radio sky survey using the recently upgraded Karl G. Jansky Very Large Array. The proposed VLASS is a modern, multi-tiered survey with the VLA designed to provide a broad, cohesive science program with forefront scientific impact, capable of generating unexpected scientific discoveries, generating involvement from all astronomical communities, and leaving a lasting legacy value for decades.VLASS will observe from 2-4 GHz and is structured to combine comprehensive all sky coverage with sequentially deeper coverage in carefully identified parts of the sky, including the Galactic plane, and will be capable of informing time domain studies. This approach enables both focused and wide ranging scientific discovery through the coupling of deeper narrower tiers with increasing sky coverage at shallower depths, addressing key science issues and providing a statistical interpretational framework. Such an approach provides both astronomers and the citizen scientist with information for every accessible point of the radio sky, while simultaneously addressing fundamental questions about the nature and evolution of astrophysical objects.VLASS will follow the evolution of galaxies and their central black hole engines, measure the strength and topology of cosmic magnetic fields, unveil hidden explosions throughout the Universe, and chart our galaxy for stellar remnants and ionized bubbles. Multi-wavelength communities studying rare objects, the Galaxy, radio transients, or galaxy evolution out to the peak of the cosmic star formation rate density will equally benefit from VLASS.Early drafts of the VLASS proposal are available at the VLASS website (https://science.nrao.edu/science/surveys/vlass/vlass), and the final proposal will be posted in early January 2015 for community comment before undergoing review in March 2015. Upon approval, VLASS would then be on schedule to start

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.

Modelling and Display of the Ultraviolet Sky

NASA Astrophysics Data System (ADS)

Daniels, J.; Henry, R.; Murthy, J.; Allen, M.; McGlynn, T. A.; Scollick, K.

1994-12-01

A computer program is currently under development to model in 3D - one dimension of which is wavelength - all the known and major speculated sources of ultraviolet (900 A - 3100 A ) radiation over the celestial sphere. The software is being written in Fortran 77 and IDL and currently operates under IRIX (the operating system of the Silicon Graphics Iris Machine); all output models are in FITS format. Models along with display software will become available to the astronomical community. The Ultraviolet Sky Model currently includes the Zodiacal Light, Point Sources of Emission, and the Diffuse Galactic Light. The Ultraviolet Sky Model is currently displayed using SkyView: a package under development at NASA/ GSFC, which allows users to retrieve and display publically available all-sky astronomical survey data (covering many wavebands) over the Internet. We present a demonstration of the SkyView display of the Ultraviolet Model. The modelling is a five year development project: the work illustrated here represents product output at the end of year one. Future work includes enhancements to the current models and incorporation of the following models: Galactic Molecular Hydrogen Fluorescence; Galactic Highly Ionized Atomic Line Emission; Integrated Extragalactic Light; and speculated sources in the intergalactic medium such as Ionized Plasma and radiation from Non-Baryonic Particle Decay. We also present a poster which summarizes the components of the Ultraviolet Sky Model and outlines a further package that will be used to display the Ultraviolet Model. This work is supported by United States Air Force Contract F19628-93-K-0004. Dr J. Daniels is supported with a post-doctoral Fellowship from the Leverhulme Foundation, London, United Kingdom. We are also grateful for the encouragement of Dr Stephen Price (Phillips Laboratory, Hanscomb Air Force Base, MA)

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.

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.

Reflective all-sky thermal infrared cloud imager

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

Redman, Brian J.; Shaw, Joseph A.; Nugent, Paul W.

A reflective all-sky imaging system has been built using a long-wave infrared microbolometer camera and a reflective metal sphere. This compact system was developed for measuring spatial and temporal patterns of clouds and their optical depth in support of applications including Earth-space optical communications. The camera is mounted to the side of the reflective sphere to leave the zenith sky unobstructed. The resulting geometric distortion is removed through an angular map derived from a combination of checkerboard-target imaging, geometric ray tracing, and sun-location-based alignment. A tape of high-emissivity material on the side of the reflector acts as a reference thatmore » is used to estimate and remove thermal emission from the metal sphere. In conclusion, once a bias that is under continuing study was removed, sky radiance measurements from the all-sky imager in the 8-14 μm wavelength range agreed to within 0.91 W/(m 2 sr) of measurements from a previously calibrated, lens-based infrared cloud imager over its 110° field of view.« less

Reflective all-sky thermal infrared cloud imager

DOE PAGES

Redman, Brian J.; Shaw, Joseph A.; Nugent, Paul W.; ...

2018-04-17

A reflective all-sky imaging system has been built using a long-wave infrared microbolometer camera and a reflective metal sphere. This compact system was developed for measuring spatial and temporal patterns of clouds and their optical depth in support of applications including Earth-space optical communications. The camera is mounted to the side of the reflective sphere to leave the zenith sky unobstructed. The resulting geometric distortion is removed through an angular map derived from a combination of checkerboard-target imaging, geometric ray tracing, and sun-location-based alignment. A tape of high-emissivity material on the side of the reflector acts as a reference thatmore » is used to estimate and remove thermal emission from the metal sphere. In conclusion, once a bias that is under continuing study was removed, sky radiance measurements from the all-sky imager in the 8-14 μm wavelength range agreed to within 0.91 W/(m 2 sr) of measurements from a previously calibrated, lens-based infrared cloud imager over its 110° field of view.« less

Reflective all-sky thermal infrared cloud imager.

PubMed

Redman, Brian J; Shaw, Joseph A; Nugent, Paul W; Clark, R Trevor; Piazzolla, Sabino

2018-04-30

A reflective all-sky imaging system has been built using a long-wave infrared microbolometer camera and a reflective metal sphere. This compact system was developed for measuring spatial and temporal patterns of clouds and their optical depth in support of applications including Earth-space optical communications. The camera is mounted to the side of the reflective sphere to leave the zenith sky unobstructed. The resulting geometric distortion is removed through an angular map derived from a combination of checkerboard-target imaging, geometric ray tracing, and sun-location-based alignment. A tape of high-emissivity material on the side of the reflector acts as a reference that is used to estimate and remove thermal emission from the metal sphere. Once a bias that is under continuing study was removed, sky radiance measurements from the all-sky imager in the 8-14 μm wavelength range agreed to within 0.91 W/(m 2 sr) of measurements from a previously calibrated, lens-based infrared cloud imager over its 110° field of view.

An All-Sky Portable (ASP) Optical Catalogue

NASA Astrophysics Data System (ADS)

Flesch, Eric Wim

2017-06-01

This optical catalogue combines the all-sky USNO-B1.0/A1.0 and most-sky APM catalogues, plus overlays of SDSS optical data, into a single all-sky map presented in a sparse binary format that is easily downloaded at 9 Gb zipped. Total count is 1 163 237 190 sources and each has J2000 astrometry, red and blue magnitudes with PSFs and variability indicator, and flags for proper motion, epoch, and source survey and catalogue for each of the photometry and astrometry. The catalogue is available on http://quasars.org/asp.html, and additional data for this paper is available at http://dx.doi.org/10.4225/50/5807fbc12595f.

SkyGlowNet as a Vehicle for STEM Education

NASA Astrophysics Data System (ADS)

Flurchick, K. M.; Craine, E. R.; Culver, R. B.; Deal, S.; Foster, C.

2013-06-01

SkyGlowNet is an emerging network of internet-enabled sky brightness meters (iSBM) that continuously record and log sky brightness at the zenith of each network node site. Also logged are time and weather information. These data are polled at a user-defined frequency, typically about every 45 seconds. The data are uploaded to the SkyGlowNet website, 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. Some of the data are periodically released to a public area on the website. In this presentation we describe the data formats and provide examples of both data content and the structure of the website. Early data from two nodes in the SkyGlowNet have been characterized, both quantitatively and qualitatively, by undergraduate students at NCAT. A summary of their work is presented here. These analyses are of utility in helping those new to looking at these data to understand how to interpret them. In particular, we demonstrate differences between effects on light at night and sky brightness due to astronomical cycles, atmospheric phenomena, and artificial lighting. Quantitative characterization of the data includes statistical analyses of parsed segments of the temporal data stream. An attempt is made to relate statistical metrics to specific types of phenomena.

Measuring high-resolution sky luminance distributions with a CCD camera.

PubMed

Tohsing, Korntip; Schrempf, Michael; Riechelmann, Stefan; Schilke, Holger; Seckmeyer, Gunther

2013-03-10

We describe how sky luminance can be derived from a newly developed hemispherical sky imager (HSI) system. The system contains a commercial compact charge coupled device (CCD) camera equipped with a fish-eye lens. The projection of the camera system has been found to be nearly equidistant. The luminance from the high dynamic range images has been calculated and then validated with luminance data measured by a CCD array spectroradiometer. The deviation between both datasets is less than 10% for cloudless and completely overcast skies, and differs by no more than 20% for all sky conditions. The global illuminance derived from the HSI pictures deviates by less than 5% and 20% under cloudless and cloudy skies for solar zenith angles less than 80°, respectively. This system is therefore capable of measuring sky luminance with the high spatial and temporal resolution of more than a million pixels and every 20 s respectively.

Accuracy of the hypothetical sky-polarimetric Viking navigation versus sky conditions: revealing solar elevations and cloudinesses favourable for this navigation method

NASA Astrophysics Data System (ADS)

Száz, Dénes; Farkas, Alexandra; Barta, András; Kretzer, Balázs; Blahó, Miklós; Egri, Ádám; Szabó, Gyula; Horváth, Gábor

2017-09-01

According to Thorkild Ramskou's theory proposed in 1967, under overcast and foggy skies, Viking seafarers might have used skylight polarization analysed with special crystals called sunstones to determine the position of the invisible Sun. After finding the occluded Sun with sunstones, its elevation angle had to be measured and its shadow had to be projected onto the horizontal surface of a sun compass. According to Ramskou's theory, these sunstones might have been birefringent calcite or dichroic cordierite or tourmaline crystals working as polarizers. It has frequently been claimed that this method might have been suitable for navigation even in cloudy weather. This hypothesis has been accepted and frequently cited for decades without any experimental support. In this work, we determined the accuracy of this hypothetical sky-polarimetric Viking navigation for 1080 different sky situations characterized by solar elevation θ and cloudiness ρ, the sky polarization patterns of which were measured by full-sky imaging polarimetry. We used the earlier measured uncertainty functions of the navigation steps 1, 2 and 3 for calcite, cordierite and tourmaline sunstone crystals, respectively, and the newly measured uncertainty function of step 4 presented here. As a result, we revealed the meteorological conditions under which Vikings could have used this hypothetical navigation method. We determined the solar elevations at which the navigation uncertainties are minimal at summer solstice and spring equinox for all three sunstone types. On average, calcite sunstone ensures a more accurate sky-polarimetric navigation than tourmaline and cordierite. However, in some special cases (generally at 35° ≤ θ ≤ 40°, 1 okta ≤ ρ ≤ 6 oktas for summer solstice, and at 20° ≤ θ ≤ 25°, 0 okta ≤ ρ ≤ 4 oktas for spring equinox), the use of tourmaline and cordierite results in smaller navigation uncertainties than that of calcite. Generally, under clear or less cloudy

The Mythology of the Night Sky

NASA Astrophysics Data System (ADS)

Falkner, David E.

The word "planet" comes from the Latin word planeta and the Greek word planes, which means "wanderer." When the ancient Greeks studied the night sky they noticed that most of the stars remained in the same position relative to all the other stars, but a few stars seem to move in the sky from day to day, week to week, and month to month. The Greeks called these rogue stars "wanderers" because they wandered through the starry background.

Mapping the Infrared Universe: The Entire WISE Sky

NASA Image and Video Library

2012-03-14

This is a mosaic of the images covering the entire sky as observed by NASA Wide-field Infrared Survey Explorer WISE, part of its All-Sky Data Release. In this mosaic, the Milky Way Galaxy runs horizontally across the map.

Introduction: The Night Sky Back Home

NASA Astrophysics Data System (ADS)

Upgren, A. R.

2001-12-01

Light pollution is a proper and fitting subject of great concern to all astronomers. Back before 1988, when the International Dark-Sky Association was founded, astronomical concern centered around and was mostly restricted to the large southwestern mountaintop observatories. This is understandable since these largest telescopes demand the darkest possible skies. The IDA was promoted and organized with this goal in mind. Today the IDA numbers almost 8000 members and is dominated by environmentalists and lighting engineers as much as or more than professional astronomers. Amateur astronomers from skygazers to those with CCD's on their telescopes are now of great importance in the realm of light pollution awareness and control. They are busy in almost every state and province working to pass ordinances restricting the worst in outdoor lighting. For example. Connecticut, a state with little professional astronomical observation, has passed the first law to require FCO (full-cutoff shielding) on every new and renovated street and highway light in the state. The needs of astronomers in places like New England differ from those of Arizona, California, and Hawaii where LPS is much preferred to HPS illumination. In the lesser climates, FCO and lumen constraints are of much greater concern. Almost every state still has very dark sky areas, well worth preserving. It is of the greatest importance for amateurs and professionals to work together to preserve dark skies wherever they are found. Our profession needs for its continued health, places near population centers where the Milky Way can still be seen. Many future astronomers will be brought into the field by the sights of a dark sky. I encourage the AAS to become more active, individually and collectively, in the multitude of efforts now in progress across the continent.

Daytime Water Detection Based on Sky Reflections

NASA Technical Reports Server (NTRS)

Rankin, Arturo L.; Matthies, Larry H.; Bellutta, Paolo

2011-01-01

Robust water detection is a critical perception requirement for unmanned ground vehicle (UGV) autonomous navigation. This is particularly true in wide-open areas where water can collect in naturally occurring terrain depressions during periods of heavy precipitation and form large water bodies. One of the properties of water useful for detecting it is that its surface acts as a horizontal mirror at large incidence angles. Water bodies can be indirectly detected by detecting reflections of the sky below the horizon in color imagery. The Jet Propulsion Laboratory (JPL) has implemented a water detector based on sky reflections that geometrically locates the pixel in the sky that is reflecting on a candidate water pixel on the ground and predicts if the ground pixel is water based on color similarity and local terrain features. This software detects water bodies in wide-open areas on cross-country terrain at mid- to far-range using imagery acquired from a forward-looking stereo pair of color cameras mounted on a terrestrial UGV. In three test sequences approaching a pond under a clear, overcast, and cloudy sky, the true positive detection rate was 100% when the UGV was beyond 7 meters of the water's leading edge and the largest false positive detection rate was 0.58%. The sky reflection based water detector has been integrated on an experimental unmanned vehicle and field tested at Ft. Indiantown Gap, PA, USA.

Full-sky, High-resolution Maps of Interstellar Dust

NASA Astrophysics Data System (ADS)

Meisner, Aaron Michael

We present full-sky, high-resolution maps of interstellar dust based on data from the Wide-field Infrared Survey Explorer (WISE) and Planck missions. We describe our custom processing of the entire WISE 12 micron All-Sky imaging data set, and present the resulting 15 arcsecond resolution, full-sky map of diffuse Galactic dust emission, free of compact sources and other contaminating artifacts. Our derived 12 micron dust map offers angular resolution far superior to that of all other existing full-sky, infrared dust emission maps, revealing a wealth of small-scale filamentary structure. We also apply the Finkbeiner et al. (1999) two-component thermal dust emission model to the Planck HFI maps. We derive full-sky 6.1 arcminute resolution maps of dust optical depth and temperature by fitting this two-component model to Planck 217-857 GHz along with DIRBE/IRAS 100 micron data. In doing so, we obtain the first ever full-sky 100-3000 GHz Planck-based thermal dust emission model, as well as a dust temperature correction with ~10 times enhanced angular resolution relative to DIRBE-based temperature maps. Analyzing the joint Planck/DIRBE dust spectrum, we show that two-component models provide a better fit to the 100-3000 GHz emission than do single-MBB models, though by a lesser margin than found by Finkbeiner et al. (1999) based on FIRAS and DIRBE. We find that, in diffuse sky regions, our two-component 100-217 GHz predictions are on average accurate to within 2.2%, while extrapolating the Planck Collaboration (2013) single-MBB model systematically underpredicts emission by 18.8% at 100 GHz, 12.6% at 143 GHz and 7.9% at 217 GHz. We calibrate our two-component optical depth to reddening, and compare with reddening estimates based on stellar spectra. We find the dominant systematic problems in our temperature/reddening maps to be zodiacal light on large angular scales and the cosmic infrared background anisotropy on small angular scales. Future work will focus on combining

The VLA Sky Survey

NASA Astrophysics Data System (ADS)

Lacy, Mark; VLASS Survey Team, VLASS Survey Science Group

2018-01-01

The VLA Sky Survey (VLASS), which began in September 2017, is a seven year project to image the entire sky north of Declination -40 degrees in three epochs. The survey is being carried out in I,Q and U polarization at a frequency of 2-4GHz, and a resolution of 2.5 arcseconds, with each epoch being separated by 32 months. Raw data from the survey, along with basic "quicklook" images are made freely available shortly after observation. Within a few months, NRAO will begin making available further basic data products, including refined images and source lists. In this talk I shall describe the science goals and methodology of the survey, the current survey status, and some early results, along with plans for collaborations with external groups to produce enhanced, high level data products.

The moon illusion: I. How high is the sky?

PubMed

Baird, J C; Wagner, M

1982-09-01

The most common explanations of the moon illusion assume that the moon is seen at a specific distance in the sky, which is perceived as a definite surface. A decrease in the apparent distance to the sky with increasing elevation presumably leads to a corresponding decrease in apparent size. In Experiment 1 observers (N = 24) gave magnitude estimates of the distance to the night sky at different elevations. The results did not support the flattened-dome hypothesis. In Experiment 2 observers (N = 20) gave magnitude estimates of the distance to the sky at points around a 360 degrees circle just above the horizon. The results were consistent with those of Experiment 1, and in addition, estimates were highly correlated with the physical distances of buildings at the horizon. In a third, control experiment, observers (N = 20) gave magnitude estimates of the distances of buildings at the horizon. A power function fit the relation between estimated and physical distance (exponent = 1.17) as well as the relation between estimates of the sky points above the buildings (Experiment 2) and estimates of building distances (exponent = .46). Taken together, the results disconfirm all theories that attribute the moon illusion to a "sky illusion" of the sort exemplified by the flattened-dome hypothesis.

Predicting the sky from 30 MHz to 800 GHz: the extended Global Sky Model

NASA Astrophysics Data System (ADS)

Liu, Adrian

We propose to construct the extended Global Sky Model (eGSM), a software package and associated data products that are capable of generating maps of the sky at any frequency within a broad range (30 MHz to 800 GHz). The eGSM is constructed from archival data, and its outputs will include not only "best estimate" sky maps, but also accurate error bars and the ability to generate random realizations of missing modes in the input data. Such views of the sky are crucial in the practice of precision cosmology, where our ability to constrain cosmological parameters and detect new phenomena (such as B-mode signatures from primordial gravitational waves, or spectral distortions of the Cosmic Microwave Background; CMB) rests crucially on our ability to remove systematic foreground contamination. Doing so requires empirical measurements of the foreground sky brightness (such as that arising from Galactic synchrotron radiation, among other sources), which are typically performed only at select narrow wavelength ranges. We aim to transcend traditional wavelength limits by optimally combining existing data to provide a comprehensive view of the foreground sky at any frequency within the broad range of 30 MHz to 800 GHz. Previous efforts to interpolate between multi-frequency maps resulted in the Global Sky Model (GSM) of de Oliveira-Costa et al. (2008), a software package that outputs foreground maps at any frequency of the user's choosing between 10 MHz and 100 GHz. However, the GSM has a number of shortcomings. First and foremost, the GSM does not include the latest archival data from the Planck satellite. Multi-frequency models depend crucially on data from Planck, WMAP, and COBE to provide high-frequency "anchor" maps. Another crucial shortcoming is the lack of error bars in the output maps. Finally, the GSM is only able to predict temperature (i.e., total intensity) maps, and not polarization information. With the recent release of Planck's polarized data products, the

Optical Sky Brightness and Transparency during the Winter Season at Dome A Antarctica from the Gattini-All-Sky Camera

NASA Astrophysics Data System (ADS)

Yang, Yi; Moore, Anna M.; Krisciunas, Kevin; Wang, Lifan; Ashley, Michael C. B.; Fu, Jianning; Brown, Peter J.; Cui, Xiangqun; Feng, Long-Long; Gong, Xuefei; Hu, Zhongwen; Lawrence, Jon S.; Luong-Van, Daniel; Riddle, Reed L.; Shang, Zhaohui; Sims, Geoff; Storey, John W. V.; Suntzeff, Nicholas B.; Tothill, Nick; Travouillon, Tony; Yang, Huigen; Yang, Ji; Zhou, Xu; Zhu, Zhenxi

2017-07-01

The summit of the Antarctic plateau, Dome A, is proving to be an excellent site for optical, near-infrared, and terahertz astronomical observations. Gattini is a wide-field camera installed on the PLATO instrument module as part of the Chinese-led traverse to Dome A in 2009 January. We present here the measurements of sky brightness with the Gattini ultra-large field of view (90^\\circ × 90^\\circ ) in the photometric B-, V-, and R-bands; cloud cover statistics measured during the 2009 winter season; and an estimate of the sky transparency. A cumulative probability distribution indicates that the darkest 10% of the nights at Dome A have sky brightness of S B = 22.98, S V = 21.86, and S R = 21.68 mag arcsec-2. These values were obtained during the year 2009 with minimum aurora, and they are comparable to the faintest sky brightness at Maunakea and the best sites of northern Chile. Since every filter includes strong auroral lines that effectively contaminate the sky brightness measurements, for instruments working around the auroral lines, either with custom filters or with high spectral resolution instruments, these values could be easily obtained on a more routine basis. In addition, we present example light curves for bright targets to emphasize the unprecedented observational window function available from this ground-based site. These light curves will be published in a future paper.

Blue Skies, Coffee Creamer, and Rayleigh Scattering

ERIC Educational Resources Information Center

Liebl, Michael

2010-01-01

The first physical explanation of Earths blue sky was fashioned in 1871 by Lord Rayleigh. Many discussions of Rayleigh scattering and approaches to studying it both in and out of the classroom are available. Rayleigh scattering accounts for the blue color of the sky and the orange/red color of the Sun near sunset and sunrise, and a number of…

The NASA SETI sky survey: Recent developments

NASA Technical Reports Server (NTRS)

Klein, M. J.; Gulkis, S.; Olsen, E. T.; Renzetti, N. A.

1989-01-01

NASA's Search for Extraterrestrial Intelligence (SETI) project utilizes two complementary search strategies: a sky survey and a targeted search. The SETI team at the Jet Propulsion Laboratory (JPL) in Pasadena, California, has primary responsibility to develop and carry out the sky survey part. Described here is progress that has been made developing the major elements of the survey including a 2-million channel wideband spectrum analyzer system that is being designed and constructed by JPL for the Deep Space Network (DSN). The system will be a multiuser instrument; it will serve as a prototype for the SETI sky survey processor. This prototype system will be used to test the signal detection and observational strategies on DSN antennas in the near future.

The NASA SETI sky survey - Recent developments

NASA Technical Reports Server (NTRS)

Klein, Michael J.; Gulkis, Samuel; Olsen, Edward T.; Renzetti, Nicholas A.

1988-01-01

NASA's Search for Extraterrestrial Intelligence (SETI) project utilizes two complimentary search strategies: a sky survey and a targeted search. The SETI team at the Jet Propulsion Laboratory have primary responsibility to develop and carry out the sky survey part of the Microwave Observing Project. The paper describes progress that has been made to develop the major elements of the survey including a two-million channel wideband spectrum analyzer system that is being developed and constructed by JPL for the Deep Space Network. The new system will be a multiuser instrument that will serve as a prototype for the SETI Sky Survey processor. This system will be used to test the signal detection and observational strategies on deep-space network antennas in the near future.

Fermi Sees the Gamma Ray Sky

NASA Image and Video Library

2009-10-30

This view of the gamma-ray sky constructed from one year of Fermi LAT observations is the best view of the extreme universe to date. The map shows the rate at which the LAT detects gamma rays with energies above 300 million electron volts -- about 120 million times the energy of visible light -- from different sky directions. Brighter colors equal higher rates. Credit: NASA/DOE/Fermi LAT Collaboration Full story: www.nasa.gov/mission_pages/GLAST/news/first_year.html

Sky online: linking amateur and professional astronomers on the world wide web

NASA Astrophysics Data System (ADS)

Fienberg, Richard Tresch

SKY Online is the World Wide Web site of Sky Publishing Corporation, publisher of Sky & Telescope magazine. Conceived mainly as an electronic extension of the company's marketing and promotion efforts, SKY Online has also proven to be a useful tool for communication between amateur and professional astronomers.

Which Observatories have the Clearest Skies? A Comparative Analysis of 2004 as Seen by the Night Sky Live Global Network of CONCAMs

NASA Astrophysics Data System (ADS)

Pereira, W. E.; Muzzin, V.; Merlo, M.; Shamir, L.; Nemiroff, R. J.; Night Sky Live Collaboration

2004-12-01

Nearly identical fisheye CONCAMs are now deployed at many major observatories as part of the Night Sky Live (NSL) global network and return real-time data to http://NightSkyLive.net . Combined, these images create a unique ability to assess and compare the relative ground-truth clarity of the skies above these observatories every few minutes. To this end, data and images from CONCAMs are used to estimate the fraction of time that stars are detectable in at least half the sky for each month of 2004. This preliminary comparison was done by visual inspection of on-line archived CONCAM images. Sites involved include Mauna Kea (Hawaii), Haleakala (Hawaii), Siding Spring (Australia), Canary Islands (Spain), Kitt Peak (Arizona), Cerro Pachon (Chile), Wise (Israel), and Sutherland (South Africa).

The Sky This Week, 2016 March 1 - 8 - Naval Oceanography Portal

Science.gov Websites

submit many observations from different locations throughout the year. This is a great time to start are here: Home › USNO › News, Tours & Events › Sky This Week › The Sky This Week, 2016 March 1 - 8 USNO Logo USNO Navigation Tour Information USNO Scientific Colloquia Sky This Week The Sky

The night sky brightness at McDonald Observatory

NASA Technical Reports Server (NTRS)

Kalinowski, J. K.; Roosen, R. G.; Brandt, J. C.

1975-01-01

Baseline observations of the night sky brightness in B and V are presented for McDonald Observatory. In agreement with earlier work by Elvey and Rudnick (1937) and Elvey (1943), significant night-to-night and same-night variations in sky brightness are found. Possible causes for these variations are discussed. The largest variation in sky brightness found during a single night is approximately a factor of two, a value which corresponds to a factor-of-four variation in airglow brightness. The data are used to comment on the accuracy of previously published surface photometry of M 81.

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.

Central neural coding of sky polarization in insects.

PubMed

Homberg, Uwe; Heinze, Stanley; Pfeiffer, Keram; Kinoshita, Michiyo; el Jundi, Basil

2011-03-12

Many animals rely on a sun compass for spatial orientation and long-range navigation. In addition to the Sun, insects also exploit the polarization pattern and chromatic gradient of the sky for estimating navigational directions. Analysis of polarization-vision pathways in locusts and crickets has shed first light on brain areas involved in sky compass orientation. Detection of sky polarization relies on specialized photoreceptor cells in a small dorsal rim area of the compound eye. Brain areas involved in polarization processing include parts of the lamina, medulla and lobula of the optic lobe and, in the central brain, the anterior optic tubercle, the lateral accessory lobe and the central complex. In the optic lobe, polarization sensitivity and contrast are enhanced through convergence and opponency. In the anterior optic tubercle, polarized-light signals are integrated with information on the chromatic contrast of the sky. Tubercle neurons combine responses to the UV/green contrast and e-vector orientation of the sky and compensate for diurnal changes of the celestial polarization pattern associated with changes in solar elevation. In the central complex, a topographic representation of e-vector tunings underlies the columnar organization and suggests that this brain area serves as an internal compass coding for spatial directions.

Central neural coding of sky polarization in insects

PubMed Central

Homberg, Uwe; Heinze, Stanley; Pfeiffer, Keram; Kinoshita, Michiyo; el Jundi, Basil

2011-01-01

Many animals rely on a sun compass for spatial orientation and long-range navigation. In addition to the Sun, insects also exploit the polarization pattern and chromatic gradient of the sky for estimating navigational directions. Analysis of polarization–vision pathways in locusts and crickets has shed first light on brain areas involved in sky compass orientation. Detection of sky polarization relies on specialized photoreceptor cells in a small dorsal rim area of the compound eye. Brain areas involved in polarization processing include parts of the lamina, medulla and lobula of the optic lobe and, in the central brain, the anterior optic tubercle, the lateral accessory lobe and the central complex. In the optic lobe, polarization sensitivity and contrast are enhanced through convergence and opponency. In the anterior optic tubercle, polarized-light signals are integrated with information on the chromatic contrast of the sky. Tubercle neurons combine responses to the UV/green contrast and e-vector orientation of the sky and compensate for diurnal changes of the celestial polarization pattern associated with changes in solar elevation. In the central complex, a topographic representation of e-vector tunings underlies the columnar organization and suggests that this brain area serves as an internal compass coding for spatial directions. PMID:21282171

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

Extended Source/Galaxy All Sky 2

NASA Image and Video Library

2003-03-27

This panoramic view encompasses the entire sky and reveals the distribution of galaxies beyond the Milky Way galaxy, which astronomers call extended sources, as observed by Two Micron All-Sky Survey. The image is assembled from a database of over 1.6 million galaxies listed in the survey’s All-Sky Survey Extended Source Catalog; more than half of the galaxies have never before been catalogued. The colors represent how the many galaxies appear at three distinct wavelengths of infrared light (blue at 1.2 microns, green at 1.6 microns, and red at 2.2 microns). Quite evident are the many galactic clusters and superclusters, as well as some streamers composing the large-scale structure of the nearby universe. The blue overlay represents the very close and bright stars from our own Milky Way galaxy. In this projection, the bluish Milky Way lies predominantly toward the upper middle and edges of the image. http://photojournal.jpl.nasa.gov/catalog/PIA04251

Big Sky and Greenhorn Elemental Comparison

NASA Image and Video Library

2015-12-17

NASA's Curiosity Mars rover examined both the "Greenhorn" and "Big Sky" targets with the rover's Alpha Particle X-ray Spectrometer (APXS) instrument. Greenhorn is located within an altered fracture zone and has an elevated concentration of silica (about 60 percent by weight). Big Sky is the unaltered counterpart for comparison. The bar plot on the left shows scaled concentrations as analyzed by Curiosity's APXS. The bar plot on the right shows what the Big Sky composition would look like if silica (SiO2) and calcium-sulfate (both abumdant in Greenhorn) were added. The similarity in the resulting composition suggests that much of the chemistry of Greenhorn could be explained by the addition of silica. Ongoing research aims to distinguish between that possible explanation for silicon enrichment and an alternative of silicon being left behind when some other elements were removed by acid weathering. http://photojournal.jpl.nasa.gov/catalog/PIA20275

Southern Ocean Iron Experiment (SOFex)

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

Coale, Kenneth H.

Southern Ocean Iron Enrichment Experiments. Seattle, WA. Geological Society of America. Coale, K., 2003. Open Ocean Iron Enrichment Experiments: What they have told us, what they have not. American Society for Limnology and Oceanography and The Oceanography Society, Honolulu, February 2004. Coale, K., 2004. Recent Research from the Southern Ocean Iron Experiment (SOFeX), in Taking the Heat: What is the impact of ocean fertilization on climate and ocean ecology? Science of earth and sky. AAAS, February 12-16, Seattle, WA« less

The Aquarius Simulator and Cold-Sky Calibration

NASA Technical Reports Server (NTRS)

Le Vine, David M.; Dinnat, Emmanuel P.; Abraham, Saji; deMatthaeis, Paolo; Wentz, Frank J.

2011-01-01

A numerical simulator has been developed to study remote sensing from space in the spectral window at 1.413 GHz (L-band), and it has been used to optimize the cold-sky calibration (CSC) for the Aquarius radiometers. The celestial sky is a common cold reference in microwave radiometry. It is currently being used by the Soil Moisture and Ocean Salinity satellite, and it is planned that, after launch, the Aquarius/SAC-D observatory will periodically rotate to view "cold sky" as part of the calibration plan. Although radiation from the celestial sky is stable and relatively well known, it varies with location. In addition, radiation from the Earth below contributes to the measured signal through the antenna back lobes and also varies along the orbit. Both effects must be taken into account for a careful calibration. The numerical simulator has been used with the Aquarius configuration (antennas and orbit) to investigate these issues and determine optimum conditions for performing a CSC. This paper provides an overview of the simulator and the analysis leading to the selection of the optimum locations for a CSC.

Colors of the Sky.

ERIC Educational Resources Information Center

Bohren, Craig F.; Fraser, Alistair B.

1985-01-01

Explains the physical principles which result in various colors of the sky. Topics addressed include: blueness, mystical properties of water vapor, ozone, fluctuation theory of scattering, variation of purity and brightness, and red sunsets and sunrises. (DH)

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.

Citizen Sky, IYA 2009 and What's To Come

NASA Astrophysics Data System (ADS)

Turner, Rebecca; Price, A.; Henden, A.

2010-01-01

Citizen Sky is a multi-year, NSF funded citizen science project involving the bright and mysterious variable star eps Aur. The project was conceived by the IYA 2009 working group on Research Experiences for Students, Teachers, and Citizen-Scientists. Citizen Sky is going beyond simple observing to include a major data analysis component. The goal is to introduce the participant to the full scientific process from background research to paper writing for a peer-reviewed journal. During IYA 2009 the Citizen Sky team was fully assembled, the website was developed and put online, and the first of two participant workshops was held. However, Citizen Sky does not stop or even slow down with the conclusion of IYA 2009. The project will continue to grow in the coming years. New participants are being recruited and trained as the observing phase of the project continues, a second participant workshop is planned for 2010, and the data analysis phase of the project will begin in earnest.

The Sky This Week, 2016 January 12 - 19 - Naval Oceanography Portal

Science.gov Websites

would be very different in that case! The planets are now beginning to span more of the night. Leading are here: Home › USNO › News, Tours & Events › Sky This Week › The Sky This Week, 2016 January 12 - 19 USNO Logo USNO Navigation Tour Information USNO Scientific Colloquia Sky This Week The Sky

The Sky This Week, 2016 February 16 - 23 - Naval Oceanography Portal

Science.gov Websites

very nice pentagon shape. The southernmost star in the pentagon, Al Nath, is "shared" as the are here: Home › USNO › News, Tours & Events › Sky This Week › The Sky This Week, 2016 February 16 - 23 USNO Logo USNO Navigation Tour Information USNO Scientific Colloquia Sky This Week The Sky

Analytic expressions for the black-sky and white-sky albedos of the cosine lobe model.

PubMed

Goodin, Christopher

2013-05-01

The cosine lobe model is a bidirectional reflectance distribution function (BRDF) that is commonly used in computer graphics to model specular reflections. The model is both simple and physically plausible, but physical quantities such as albedo have not been related to the parameterization of the model. In this paper, analytic expressions for calculating the black-sky and white-sky albedos from the cosine lobe BRDF model with integer exponents will be derived, to the author's knowledge for the first time. These expressions for albedo can be used to place constraints on physics-based simulations of radiative transfer such as high-fidelity ray-tracing simulations.

Automated exploitation of sky polarization imagery.

PubMed

Sadjadi, Firooz A; Chun, Cornell S L

2018-03-10

We propose an automated method for detecting neutral points in the sunlit sky. Until now, detecting these singularities has been done manually. Results are presented that document the application of this method on a limited number of polarimetric images of the sky captured with a camera and rotating polarizer. The results are significant because a method for automatically detecting the neutral points may aid in the determination of the solar position when the sun is obscured and may have applications in meteorology and pollution detection and characterization.

Clear-Sky Narrowband Albedo Datasets Derived from Modis Data

NASA Astrophysics Data System (ADS)

Chen, Y.; Minnis, P.; Sun-Mack, S.; Arduini, R. F.; Hong, G.

2013-12-01

Satellite remote sensing of clouds requires an accurate estimate of the clear-sky radiances for a given scene to detect clouds and aerosols and to retrieve their microphysical properties. Knowing the spatial and angular variability of clear-sky albedo is essential for predicting the clear-sky radiance at solar wavelengths. The Clouds and the Earth's Radiant Energy System (CERES) Project uses the near-infrared (NIR; 1.24, 1.6 or 2.13 μm) and visible (VIS; 0.63 μm) channels available on the Terra and Aqua Moderate Resolution Imaging Spectroradiometers (MODIS) to help identify clouds and retrieve their properties. Generally, clear-sky albedo for a given surface type is determined for conditions when the vegetation is either thriving or dormant and free of snow. The clear-sky albedos are derived using a radiative transfer parameterization of the impact of the atmosphere, including aerosols, on the observed reflectances. This paper presents the method of generating monthly clear-sky overhead albedo maps for both snow-free and snow-covered surfaces of these channels using one year of MODIS (Moderate Resolution Imaging Spectroradiometer) CERES products. Maps of 1.24 and 1.6 μm are being used as the background to help retrieve cloud properties (e.g., effective particle size, optical depth) in CERES cloud retrievals in both snow-free and snow-covered conditions.

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.

Sky Brightness During Eclipses: A Compendium from the Literature

DTIC Science & Technology

1974-08-05

86 25. Absolute Values of Luminance of the Terrain and the Sky 88 26. Sky Brightness From Film No. 1 89 27. Sky Brightness From Film No. 2 89 28...these twilight equivalents when dust is present in the r.tmosphere are also difficult. Both involve the passage of light through long path lengths...purposes." Ilford-Selo, HP-3 isopan film with a sensitivity of 800 H & D was used. The measurement of the photographs was performed by means of a

Most Efficient Spectrograph to Shoot the Southern Skies

NASA Astrophysics Data System (ADS)

2009-05-01

ESO's Very Large Telescope -- Europe's flagship facility for ground-based astronomy -- has been equipped with the first of its second generation instruments: X-shooter. It can record the entire spectrum of a celestial object in one shot -- from the ultraviolet to the near-infrared -- with high sensitivity. This unique new instrument will be particularly useful for the study of distant exploding objects called gamma-ray bursts. ESO PR Photo 20a/09 An X-shooter spectrum ESO PR Photo 20b/09 The X-shooter instrument ESO PR Photo 20c/09 First Light of X-shooter "X-shooter offers a capability that is unique among astronomical instruments installed at large telescopes," says Sandro D'Odorico, who coordinated the Europe-wide consortium of scientists and engineers that built this remarkable instrument. "Until now, different instruments at different telescopes and multiple observations were needed to cover this kind of wavelength range, making it very difficult to compare data, which, even though from the same object, could have been taken at different times and under different sky conditions." X-shooter collects the full spectrum from the ultraviolet (300 nm) to the near-infrared (2400 nm) in parallel, capturing up to half of all the light from an object that passes through the atmosphere and the various elements of the telescope. "All in all, X-shooter can save us a factor of three or more in terms of precious telescope time and opens a new window of opportunity for the study of many, still poorly understood, celestial sources," says D'Odorico. The name of the 2.5-ton instrument was chosen to stress its capacity to capture data highly efficiently from a source whose nature and energy distribution are not known in advance of the observation. This property is particularly crucial in the study of gamma-ray bursts, the most energetic explosions known to occur in the Universe (ESO 17/09). Until now, a rough estimate of the distance of the target was needed, so as to know which

An Effective Method for Modeling Two-dimensional Sky Background of LAMOST

NASA Astrophysics Data System (ADS)

Haerken, Hasitieer; Duan, Fuqing; Zhang, Jiannan; Guo, Ping

2017-06-01

Each CCD of LAMOST accommodates 250 spectra, while about 40 are used to observe sky background during real observations. How to estimate the unknown sky background information hidden in the observed 210 celestial spectra by using the known 40 sky spectra is the problem we solve. In order to model the sky background, usually a pre-observation is performed with all fibers observing sky background. We use the observed 250 skylight spectra as training data, where those observed by the 40 fibers are considered as a base vector set. The Locality-constrained Linear Coding (LLC) technique is utilized to represent the skylight spectra observed by the 210 fibers with the base vector set. We also segment each spectrum into small parts, and establish the local sky background model for each part. Experimental results validate the proposed method, and show the local model is better than the global model.

The Citizen Sky Planetarium Trailer

NASA Astrophysics Data System (ADS)

Turner, Rebecca; Price, A.; Wyatt, R.

2011-05-01

Citizen Sky is a multi-year, citizen science project focusing on the bright variable star, epsilon Aurigae. We have developed a six-minute video presentation describing eclipsing binary stars, light curves, and the Citizen Sky project. Designed like a short movie trailer, the video can be shown at planetariums before their regular, feature shows or integrated into a longer presentation. The trailer is available in a wide range of formats for viewing on laptops all the way up to state-of-the-art planetariums. The show is narrated by Timothy Ferris and was produced by the Morrison Planetarium and Visualization Studio at the California Academy of Sciences. This project has been made possible by the National Science Foundation.

The ADS All Sky Survey: footprints of astronomy literature, in the sky

NASA Astrophysics Data System (ADS)

Pepe, Alberto; Goodman, A. A.; Muench, A. A.; Seamless Astronomy Group at the CfA

2014-01-01

The ADS All-Sky Survey (ADSASS) aims to transform the NASA Astrophysics Data System (ADS), widely known for its unrivaled value as a literature resource for astronomers, into a data resource. The ADS is not a data repository per se, but it implicitly contains valuable holdings of astronomical data, in the form of images, tables and object references contained within articles. The objective of the ADSASS effort is to extract these data and make them discoverable and available through existing data viewers. In this talk, the ADSASS viewer - http://adsass.org/ - will be presented: a sky heatmap of astronomy articles based on the celestial objects they reference. The ADSASS viewer is as an innovative research and visual search tool for it allows users to explore astronomical literature based on celestial location, rather than keyword string. The ADSASS is a NASA-funded initiative carried out by the Seamless Astronomy Group at the Harvard-Smithsonian Center for Astrophysics.

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?

A new technique for measuring aerosols with moonlight observations and a sky background model

NASA Astrophysics Data System (ADS)

Jones, Amy; Noll, Stefan; Kausch, Wolfgang; Kimeswenger, Stefan; Szyszka, Ceszary; Unterguggenberger, Stefanie

2014-05-01

There have been an ample number of studies on aerosols in urban, daylight conditions, but few for remote, nocturnal aerosols. We have developed a new technique for investigating such aerosols using our sky background model and astronomical observations. With a dedicated observing proposal we have successfully tested this technique for nocturnal, remote aerosol studies. This technique relies on three requirements: (a) sky background model, (b) observations taken with scattered moonlight, and (c) spectrophotometric standard star observations for flux calibrations. The sky background model was developed for the European Southern Observatory and is optimized for the Very Large Telescope at Cerro Paranal in the Atacama desert in Chile. This is a remote location with almost no urban aerosols. It is well suited for studying remote background aerosols that are normally difficult to detect. Our sky background model has an uncertainty of around 20 percent and the scattered moonlight portion is even more accurate. The last two requirements are having astronomical observations with moonlight and of standard stars at different airmasses, all during the same night. We had a dedicated observing proposal at Cerro Paranal with the instrument X-Shooter to use as a case study for this method. X-Shooter is a medium resolution, echelle spectrograph which covers the wavelengths from 0.3 to 2.5 micrometers. We observed plain sky at six different distances (7, 13, 20, 45, 90, and 110 degrees) to the Moon for three different Moon phases (between full and half). Also direct observations of spectrophotometric standard stars were taken at two different airmasses for each night to measure the extinction curve via the Langley method. This is an ideal data set for testing this technique. The underlying assumption is that all components, other than the atmospheric conditions (specifically aerosols and airglow), can be calculated with the model for the given observing parameters. The scattered

Strategy for the IRAS all-sky survey

NASA Technical Reports Server (NTRS)

Lundy, S. A.

1984-01-01

IRAS (the Infrared Astronomical Satellite) was launched on January 25, 1983 (January 26 GMT) with the primary purpose of performing an infrared survey of the entire celestial sphere. To ensure completeness and reliability, every point of sky was to be covered by a minimum of four separate scans of the telescope field-of-view, and as much as possible with six, with certain added timing constraints on the elapsed interval between scans. These strong requirements for sky coverage, combined with a restricted, rotating viewing-window, made extensive planning for the survey strategy, both pre-launch and during operations, a necessity. The result was that on November 21 (November 22 GMT), when the liquid helium required for cooling was depleted, 96 percent of the sky was covered to the minimum depth of four and 71 percent was coverd to depth six or more.

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.

AmeriFlux US-SO4 Sky Oaks- New Stand

DOE Data Explorer

Oechel, Walt [San Diego State University

2016-01-01

This is the AmeriFlux version of the carbon flux data for the site US-SO4 Sky Oaks- New Stand. Site Description - The Sky Oaks New site is located near the Sky Oaks Field station, owned and operated by San Diego State University. Chaparral vegetation, associated with a Mediterranean climate, covers nearly half of the rough and rocky terrain. Precipitation is almost exclusively confined to the winter months. During the summer and early fall, hot and dry Santa Ana winds from the northeast bring desert heat to the site. A high intensity natural wildfire occurred in approximately 1905. Physical characteristics prior to the 1905 burn are unknown, including stand age and canopy height. Currently, the Sky Oaks New site is an excellent representation of an old-growth chaparral ecosystem, with a canopy height of 2.3 m and chamise-dominated overstory.

An All Sky Instantaneous Shortwave Solar Radiation Model for Mountainous Terrain

NASA Astrophysics Data System (ADS)

Zhang, S.; Li, X.; She, J.

2017-12-01

In mountainous terrain, solar radiation shows high heterogeneity in space and time because of strong terrain shading effects and significant variability of cloud cover. While existing GIS-based solar radiation models simulate terrain shading effects with relatively high accuracy and models based on satellite datasets consider fine scale cloud attenuation processes, none of these models have considered the geometrical relationships between sun, cloud, and terrain, which are important over mountainous terrain. In this research we propose sky cloud maps to represent cloud distribution in a hemispherical sky using MODIS cloud products. By overlaying skyshed (visible area in the hemispherical sky derived from DEM), sky map, and sky cloud maps, we are able to consider both terrain shading effects and anisotropic cloud attenuation in modeling instantaneous direct and diffuse solar radiation in mountainous terrain. The model is evaluated with field observations from three automatic weather stations in the Tizinafu watershed in the Kunlun Mountains of northwestern China. Overall, under all sky conditions, the model overestimates instantaneous global solar radiation with a mean absolute relative difference (MARD) of 22%. The model is also evaluated under clear sky (clearness index of more than 0.75) and partly cloudy sky (clearness index between 0.35 and 0.75) conditions with MARDs of 5.98% and 23.65% respectively. The MARD for very cloudy sky (clearness index less than 0.35) is relatively high. But these days occur less than 1% of the time. The model is sensitive to DEM data error, algorithms used in delineating skyshed, and errors in MODIS atmosphere and cloud products. Our model provides a novel approach for solar radiation modeling in mountainous areas.

Extended Source/Galaxy All Sky 1

NASA Image and Video Library

2003-03-27

This panoramic view of the entire sky reveals the distribution of galaxies beyond our Milky Way galaxy, which astronomers call extended sources, as observed by Two Micron All-Sky Survey. The image is constructed from a database of over 1.6 million galaxies listed in the survey's Extended Source Catalog; more than half of the galaxies have never before been catalogued. The image is a representation of the relative brightnesses of these million-plus galaxies, all observed at a wavelength of 2.2 microns. The brightest and nearest galaxies are represented in blue, and the faintest, most distant ones are in red. This color scheme gives insights into the three dimensional large-scale structure of the nearby universe with the brightest, closest clusters and superclusters showing up as the blue and bluish-white features. The dark band in this image shows the area of the sky where our Milky Way galaxy blocks our view of distant objects, which, in this projection, lies predominantly along the edges of the image. http://photojournal.jpl.nasa.gov/catalog/PIA04252

Aladin Lite: Lightweight sky atlas for browsers

NASA Astrophysics Data System (ADS)

Boch, Thomas

2014-02-01

Aladin Lite is a lightweight version of the Aladin tool, running in the browser and geared towards simple visualization of a sky region. It allows visualization of image surveys (JPEG multi-resolution HEALPix all-sky surveys) and permits superimposing tabular (VOTable) and footprints (STC-S) data. Aladin Lite is powered by HTML5 canvas technology and is easily embeddable on any web page and can also be controlled through a Javacript API.

Data indexing techniques for the EUVE all-sky survey

NASA Technical Reports Server (NTRS)

Lewis, J.; Saba, V.; Dobson, C.

1992-01-01

This poster describes techniques developed for manipulating large full-sky data sets for the Extreme Ultraviolet Explorer project. The authors have adapted the quatrilateralized cubic sphere indexing algorithm to allow us to efficiently store and process several types of large data sets, such as full-sky maps of photon counts, exposure time, and count rates. A variation of this scheme is used to index sparser data such as individual photon events and viewing times for selected areas of the sky, which are eventually used to create EUVE source catalogs.

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.

Coevolution of nonlinear trends in vegetation, soils, and topography with elevation and slope aspect: A case study in the sky islands of southern Arizona

NASA Astrophysics Data System (ADS)

Pelletier, Jon D.; Barron-Gafford, Greg A.; Breshears, David D.; Brooks, Paul D.; Chorover, Jon; Durcik, Matej; Harman, Ciaran J.; Huxman, Travis E.; Lohse, Kathleen A.; Lybrand, Rebecca; Meixner, Tom; McIntosh, Jennifer C.; Papuga, Shirley A.; Rasmussen, Craig; Schaap, Marcel; Swetnam, Tyson L.; Troch, Peter A.

2013-06-01

among vegetation dynamics, pedogenesis, and topographic development affect the "critical zone"—the living filter for Earth's hydrologic, biogeochemical, and rock/sediment cycles. Assessing the importance of such feedbacks, which may be particularly pronounced in water-limited systems, remains a fundamental interdisciplinary challenge. The sky islands of southern Arizona offer an unusually well-defined natural experiment involving such feedbacks because mean annual precipitation varies by a factor of five over distances of approximately 10 km in areas of similar rock type (granite) and tectonic history. Here we compile high-resolution, spatially distributed data for Effective Energy and Mass Transfer (EEMT: the energy available to drive bedrock weathering), above-ground biomass, soil thickness, hillslope-scale topographic relief, and drainage density in two such mountain ranges (Santa Catalina: SCM; Pinaleño: PM). Strong correlations exist among vegetation-soil-topography variables, which vary nonlinearly with elevation, such that warm, dry, low-elevation portions of these ranges are characterized by relatively low above-ground biomass, thin soils, minimal soil organic matter, steep slopes, and high drainage densities; conversely, cooler, wetter, higher elevations have systematically higher biomass, thicker organic-rich soils, gentler slopes, and lower drainage densities. To test if eco-pedo-geomorphic feedbacks drive this pattern, we developed a landscape evolution model that couples pedogenesis and topographic development over geologic time scales, with rates explicitly dependent on vegetation density. The model self-organizes into states similar to those observed in SCM and PM. Our results highlight the potential importance of eco-pedo-geomorphic feedbacks, mediated by soil thickness, in water-limited systems.

eGSM: A extended Sky Model of Diffuse Radio Emission

NASA Astrophysics Data System (ADS)

Kim, Doyeon; Liu, Adrian; Switzer, Eric

2018-01-01

Both cosmic microwave background and 21cm cosmology observations must contend with astrophysical foreground contaminants in the form of diffuse radio emission. For precise cosmological measurements, these foregrounds must be accurately modeled over the entire sky Ideally, such full-sky models ought to be primarily motivated by observations. Yet in practice, these observations are limited, with data sets that are observed not only in a heterogenous fashion, but also over limited frequency ranges. Previously, the Global Sky Model (GSM) took some steps towards solving the problem of incomplete observational data by interpolating over multi-frequency maps using principal component analysis (PCA).In this poster, we present an extended version of GSM (called eGSM) that includes the following improvements: 1) better zero-level calibration 2) incorporation of non-uniform survey resolutions and sky coverage 3) the ability to quantify uncertainties in sky models 4) the ability to optimally select spectral models using Bayesian Evidence techniques.

Accuracy of the hypothetical sky-polarimetric Viking navigation versus sky conditions: revealing solar elevations and cloudinesses favourable for this navigation method.

PubMed

Száz, Dénes; Farkas, Alexandra; Barta, András; Kretzer, Balázs; Blahó, Miklós; Egri, Ádám; Szabó, Gyula; Horváth, Gábor

2017-09-01

According to Thorkild Ramskou's theory proposed in 1967, under overcast and foggy skies, Viking seafarers might have used skylight polarization analysed with special crystals called sunstones to determine the position of the invisible Sun. After finding the occluded Sun with sunstones, its elevation angle had to be measured and its shadow had to be projected onto the horizontal surface of a sun compass. According to Ramskou's theory, these sunstones might have been birefringent calcite or dichroic cordierite or tourmaline crystals working as polarizers. It has frequently been claimed that this method might have been suitable for navigation even in cloudy weather. This hypothesis has been accepted and frequently cited for decades without any experimental support. In this work, we determined the accuracy of this hypothetical sky-polarimetric Viking navigation for 1080 different sky situations characterized by solar elevation θ and cloudiness ρ , the sky polarization patterns of which were measured by full-sky imaging polarimetry. We used the earlier measured uncertainty functions of the navigation steps 1, 2 and 3 for calcite, cordierite and tourmaline sunstone crystals, respectively, and the newly measured uncertainty function of step 4 presented here. As a result, we revealed the meteorological conditions under which Vikings could have used this hypothetical navigation method. We determined the solar elevations at which the navigation uncertainties are minimal at summer solstice and spring equinox for all three sunstone types. On average, calcite sunstone ensures a more accurate sky-polarimetric navigation than tourmaline and cordierite. However, in some special cases (generally at 35° ≤  θ  ≤ 40°, 1 okta ≤  ρ  ≤ 6 oktas for summer solstice, and at 20° ≤  θ  ≤ 25°, 0 okta ≤  ρ  ≤ 4 oktas for spring equinox), the use of tourmaline and cordierite results in smaller navigation uncertainties than that of calcite

NRAO Makes Available VLA Sky Survey Maps

NASA Astrophysics Data System (ADS)

1994-06-01

An original and comprehensive data set potentially full of scientific surprises now is available to astronomers, students and the public through the information superhighway. Radio images of the sky produced by the Very Large Array radio telescope -- one of the premier astronomical instruments in the world -- as part of a massive survey now are stored in an electronic repository avail- able over the Internet computer communications network. "Each of these sensitive new sky maps shows about a thou- sand radio-emitting objects, most of which have never been seen before," said Dr. J. J. Condon, leader of the National Radio As- tronomy Observatory (NRAO) survey team. "We are releasing them as soon as they are completed because they contain more data than we could possibly analyze by ourselves." "By using electronic distribution, we can open this tre- mendous resource of information for computer analysis by all as- tronomers immediately, without waiting for traditional publication," Condon added. The radio images are copyright NRAO/ AUI. Permission is granted for use of the material without charge for scholarly, educational and private non-commercial purposes. "It is entirely conceivable -- even probable -- that valuable discoveries will be made by students or amateur astrono- mers who devote the time to study these maps carefully," said team member Dr. W. D. Cotton. "Making this new information available electronically means that more people can participate in adding to its scientific value." The maps are a product of the NRAO VLA Sky Survey (NVSS), which began its observational phase in September of 1993 and will cover 82 percent of the sky when completed by the end of 1996. The NVSS is expected to produce a catalog of more than two million ra- dio-emitting objects in the sky, and it is the first sky survey sensitive to linearly polarized emission from radio sources beyond our own Milky Way galaxy. "The NVSS is being made as a service to the entire astronomical

Worldwide Impact: International Year of Astronomy Dark Skies Awareness Programs

NASA Astrophysics Data System (ADS)

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

2009-12-01

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 Awareness” is a global 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 through: - New Technology (website, podcasts, social networking, Second Life) - Educational Materials (Great Switch Out, a traveling exhibit, brochures, posters, CDs, DVDs, educational kit) - The Arts (photo contest) - Events (Earth Hour, International Dark Sky Week, World Night in Defense of Starlight, Dark Skies Discovery Sites, Sidewalk Astronomy, Nights in the Parks) - Citizen Science Programs (5 star hunting programs & Quiet Skies) Dark Skies Communities (Starlight Initiative, International Dark Sky Communities) Many countries around the world have participated in these programs. We will highlight 24 countries in particular and focus on successful techniques used in aspects of the programs, results and impact on the audience, and plans and challenges for maintaining or extending the program beyond the International Year of Astronomy. The International Year of Astronomy 2009 is partially funded from a grant from the National Science Foundation (NSF) Astronomy Division. The National Optical Astronomy Observatory is host to the IYA2009 Dark Skies Awareness programs and is operated by the Association of Universities for Research in Astronomy, Inc. under cooperative agreement with NSF.

Dark Skies, Bright Kids! Year 5

NASA Astrophysics Data System (ADS)

Prager, Brian; Johnson, K. E.; Barcos-Munoz, L. D.; Beaton, R.; Bittle, L.; Borish, H.; Burkhardt, A.; Corby, J.; Damke, G.; Dean, J.; Dorsey, G.; Graninger, D.; Lauck, T.; Liss, S.; Oza, A.; Peacock, S.; Romero, C.; Sokal, K. R.; Stierwalt, S.; Walker, L.; Wenger, T.; Zucker, C.

2014-01-01

Our public outreach group Dark Skies, Bright Kids! (DSBK) fosters science literacy in Virginia by bringing a hands-on approach to astronomy that engages children's natural excitement and curiosity. We are an entirely volunteer-run group based out of the Department of Astronomy at the University of Virginia and we enthusiastically utilize astronomy as a 'gateway science.' We create long-term relationships with students during an 8 to 10 week long, after-school astronomy club at under served elementary schools in neighboring counties, and we visited 3 different schools in 2013. Additionally, we organize and participate in science events throughout the community. The fifth year of DSBK was marked by surpassing 10,000 contact hours in Spring 2013 Semester and by ringing in the fall semester with our biggest, most successful star party to date. We hosted the Third Annual Central Virginia Star Party, free and open to the community to encourage families to enjoy astronomy together. Nearly four hundred people of all ages attended, double the number from previous years. Joining with local astronomical societies, we offered an enlightening and exciting night with resources rarely accessible to the public, such as an IR camera and a portable planetarium. With numerous telescopes pointed at the sky, and a beautifully clear night with views of the Milky Way, the International Space Station, and numerous meteors, the star party was a fantastic opportunity to introduce many of our guests to the natural wonders of our night sky and enjoy some of the darkest skies on the eastern seaboard.

ESASky: All the sky you need

NASA Astrophysics Data System (ADS)

De Marchi, Guido; ESASky Team

2018-06-01

ESASky is a discovery portal giving to all astronomers, professional and amateur alike, an easy way to access high-quality scientific data from their computer, tablet, or mobile device. It includes over half a million images, 300,000 spectra, and more than a billion catalogue sources. From gamma rays to radio wavelengths, it allows users to explore the cosmos with data from a dozen space missions from the astronomical archives of ESA, NASA, and JAXA and does not require prior knowledge of any particular mission. ESASky features an all-sky exploration interface, letting users easily zoom in for stars as single targets or as part of a whole galaxy, visualise them and retrieve the relevant data taken in an area of the sky with just a few clicks. Users can easily compare observations of the same source obtained by different space missions at different times and wavelengths. They can also use ESASky to plan future observations with the James Webb Space Telescope, comparing the relevant portion of the sky as observed by Hubble and other missions. We will illustrate the many options to visualise and access astronomical data: interactive footprints for each instrument, tree-maps, filters, and solar-system object trajectories can all be combined and displayed. The most recent version of ESASky, released in February, also includes access to scientific publications, allowing users to visualise on the sky all astronomical objects with associated scientific publications and to link directly back to the papers in the NASA Astrophysics Data System.

NASA SETI microwave observing project: Sky Survey element

NASA Technical Reports Server (NTRS)

Klein, M. J.

1991-01-01

The SETI Sky Survey Observing Program is one of two complimentary strategies that NASA plans to use in its microwave Search for Extraterrestrial Intelligence (SETI). The primary objective of the sky survey is to search the entire sky over the frequency range of 1.0 to 10.0 GHz for evidence of narrow band signals of extraterrestrial intelligent origin. Frequency resolutions of 30 Hz or narrower will be used across the entire band. Spectrum analyzers with upwards of ten million channels are required to keep the survey time approximately 6 years. Data rates in excess of 10 megabits per second will be generated in the data taking process. Sophisticated data processing techniques will be required to determine the ever changing receiver baselines, and to detect and archive potential SETI signals. Existing radio telescopes, including several of NASA's Deep Space Network (DSN) 34 meter antennas located at Goldstone, CA and Tidbinbilla, Australia will be used for the observations. The JPL has the primary responsibility to develop and carry out the sky survey. In order to lay the foundation for the full scale SETI Sky Survey, a prototype system is being developed at the JPL. The system will be installed at the new 34-m high efficiency antenna at the Deep Space Station (DSS) 13 research and development station, Goldstone, CA, where it will be used to initiate the observational phase of the NASA SETI Sky Survey. It is anticipated that the early observations will be useful to test signal detection algorithms, scan strategies, and radio frequency interference rejection schemes. The SETI specific elements of the prototype system are: (1) the Wide Band Spectrum Analyzer (WBSA); a 2-million channel fast Fourier transformation (FFT) spectrum analyzer which covers an instantaneous bandpass of 40 MHz; (2) the signal detection processor; and (3) the SETI Sky Survey Manager, a network-based C-language environment that provides observatory control, performs data acquisition and analysis

The Citizen Sky Planetarium Trailer

NASA Astrophysics Data System (ADS)

Turner, R.; Price, A.; Wyatt, R.

2012-06-01

(Abstract only) Citizen Sky is a multi-year, citizen science project focusing on the bright variable star e Aurigae. We have developed a six-minute video presentation describing eclipsing binary stars, light curves, and the Citizen Sky project. Designed like a short movie trailer, the video can be shown at planetariums before their regular, feature shows or integrated into a longer presentation. The trailer is available in a wide range of formats for viewing on laptops all the way up to state-of-the-art planetariums. The show is narrated by Timothy Ferris and was produced by the Morrison Planetarium and Visualization Studio at the California Academy of Sciences. This project has been made possible by the National Science Foundation.

Study of UV cloud modification factors in Southern Patagonia

NASA Astrophysics Data System (ADS)

Wolfram, Elian A.; Orte, Facundo; Salvador, Jacobo; Quiroga, Jonathan; D'Elia, Raúl; Antón, Manuel; Alados-Arboledas, Lucas; Quel, Eduardo

2017-02-01

Anthropogenic perturbation of the ozone layer has induced change in the amount of UV radiation that reaches the Earth's surface, mainly through the Antarctic ozone hole, making the ozone and ultraviolet (UV) radiation two important issues in the study of Earth atmosphere in the scientific community. Also the clouds have been identified as the main modulator of UV amount in short time scales and produce the main source of uncertainty in the projection of surface UV level as consequence of projected ozone recovery. While clouds can decrease direct radiation, they can produce an increase in the diffuse component, and as consequence the surface UV radiation may be higher than an equivalent clear sky scenario for several minutes. In particular this situation can be important when low ozone column and partially cloud cover skies happen simultaneously. These situations happen frequently in southern Patagonia, where the CEILAP Lidar Division has established the Atmospheric Observatory of Southern Patagonia, an atmospheric remote sensing site near the city of Río Gallegos (51°55'S, 69°14'W). In this paper, the impact of clouds over the UV radiation is investigated by the use of ground based measurements from the passive remote sensing instruments operating at this site, mainly of broad and moderate narrow band filter radiometers. We analyzed the UV Index obtained from a multiband filter radiometer GUV-541 (UVI) [Biospherical Inc.] installed in the Observatorio Atmosférico de la Patagonia Austral, Río Gallegos, since 2005. Cloud modification factors (CMF, ratio between the measured UV radiation in a cloudy sky and the simulated radiation under cloud-free conditions) are evaluated for the study site. The database used in this work covers the period 2005-2012 for spring and summer seasons, when the ozone hole can affect these subpolar regions. CMF higher than 1 are found during spring and summer time, when lower total ozone columns, higher solar elevations and high cloud

Tropical rainforest response to marine sky brightening climate engineering

NASA Astrophysics Data System (ADS)

Muri, Helene; Niemeier, Ulrike; Kristjánsson, Jón Egill

2015-04-01

Tropical forests represent a major atmospheric carbon dioxide sink. Here the gross primary productivity (GPP) response of tropical rainforests to climate engineering via marine sky brightening under a future scenario is investigated in three Earth system models. The model response is diverse, and in two of the three models, the tropical GPP shows a decrease from the marine sky brightening climate engineering. Partial correlation analysis indicates precipitation to be important in one of those models, while precipitation and temperature are limiting factors in the other. One model experiences a reversal of its Amazon dieback under marine sky brightening. There, the strongest partial correlation of GPP is to temperature and incoming solar radiation at the surface. Carbon fertilization provides a higher future tropical rainforest GPP overall, both with and without climate engineering. Salt damage to plants and soils could be an important aspect of marine sky brightening.

2014 Southern δ-Aquariid observing campaign - carried out from Crete

NASA Astrophysics Data System (ADS)

Weiland, T.

2016-01-01

With a peak ZHR of 15-20 at the end of July, the Southern δ-Aquariids rank as a major annual shower, but observation is often neglected in favor of the much more active Perseids of August, mainly as a consequence of their southerly radiant, which makes the stream a prominent target from low latitudes and the southern hemisphere. The extended activity period of more than a month, lacking a distinctive peak, and the paucity of bright meteors does not enhance interest of most observers, either. Nevertheless, one has not to go too far south in order to monitor the stream properly to gain scientific results. The Greek island of Crete, at the southernmost tip of Europe, is such a place, offering sufficiently dark skies and a 90 % probability of clear weather in July and August. Encouraged by a New Moon on July 26th an eight-night-long visual observing campaign was carried out in 2014. As a consequence, I managed to record nearly 250 Southern δ-Aquariids within 40 hours of effective observing time. An impression of the campaign together with a summary of the results is presented.

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.

Alternative Fuels Data Center: Blue Skies Initiative Clears the Air in

Science.gov Websites

North Carolina for More Than a Decade Blue Skies Initiative Clears the Air in North Carolina for More Than a Decade to someone by E-mail Share Alternative Fuels Data Center: Blue Skies Initiative Center: Blue Skies Initiative Clears the Air in North Carolina for More Than a Decade on Twitter Bookmark

Introduction to the Arizona Sky Island Arthropod Project (ASAP): Systematics, biogeography, ecology, and population genetics of arthropods of the Madrean Sky Islands

Treesearch

Wendy Moore; Wallace M. Meyer; Jeffrey A. Eble; Kimberly Franklin; John F. Wiens; Richard C. Brusca

2013-01-01

The Arizona Sky Island Arthropod Project (ASAP) is a new multi-disciplinary research program at the University of Arizona that combines systematics, biogeography, ecology, and population genetics to study origins and patterns of arthropod diversity along elevation gradients and among mountain ranges in the Madrean Sky Island Region. Arthropods represent taxonomically...

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.

All Sky Observations with BATSE and GBM

NASA Technical Reports Server (NTRS)

Wilson-Hodge, Colleen A.

2008-01-01

The Burst and Transient Source Experiment (BATSE) on board the Compton Gamma Ray Observatory (CGRO) monitored the entire sky from 1991-2000. I will review highlights of BATSE observations including gamma ray bursts, black hole candidates, accreting pulsars, and active galaxies. On 2008 June 11, the Fermi Gamma Ray Space Telescope was launched. The Gamma ray Burst Monitor (GBM) on board Fermi continues the all-sky monitoring legacy started with BATSE. I will review early results and planned observations with GBM.

Using Virtual Observatory Services in Sky View

NASA Technical Reports Server (NTRS)

McGlynn, Thomas A.

2007-01-01

For over a decade Skyview has provided astronomers and the public with easy access to survey and imaging data from all wavelength regimes. SkyView has pioneered many of the concepts that underlie the Virtual Observatory. Recently SkyView has been released as a distributable package which uses VO protocols to access image and catalog services. This chapter describes how to use the Skyview as a local service and how to customize it to access additional VO services and local data.

Night Sky preservation and restoration in U.S. National Parks

NASA Astrophysics Data System (ADS)

Duriscoe, Dan M.; Ament, Nate

2015-08-01

The U.S. National Park Service (NPS) Night Skies Program contributes to the recognition of certain outstanding NPS lands as dark sky places. A combination of efforts including measuring resource condition, within-park outdoor lighting control, education outreach for visitors, and engagement with surrounding communities helps establish and maintain such places. In certain circumstances, communities and protected areas join forces in a cooperative effort to preserve the natural nocturnal environment of a region. One recent example, the Colorado Plateau Dark Sky Cooperative, is taking lighting, conservation, and educational steps to fulfill the mission of the NPS Call To Action- Starry Starry Night. This voluntary initiative forms America’s first Dark Sky Cooperative, and links communities, tribes, businesses, state/federal agencies, and citizens in a collaborative effort to celebrate the view of the cosmos, minimize the impact of outdoor lighting, and ultimately restore natural darkness to the area. We[AN1] present progress and accomplishments of established dark sky parks and reserves in the western U.S., with particular emphasis on public response to the actions taken and the results achieved.

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

The new world atlas of artificial night sky brightness

PubMed Central

Falchi, Fabio; Cinzano, Pierantonio; Duriscoe, Dan; Kyba, Christopher C. M.; Elvidge, Christopher D.; Baugh, Kimberly; Portnov, Boris A.; Rybnikova, Nataliya A.; Furgoni, Riccardo

2016-01-01

Artificial lights raise night sky luminance, creating the most visible effect of light pollution—artificial skyglow. Despite the increasing interest among scientists in fields such as ecology, astronomy, health care, and land-use planning, light pollution lacks a current quantification of its magnitude on a global scale. To overcome this, we present the world atlas of artificial sky luminance, computed with our light pollution propagation software using new high-resolution satellite data and new precision sky brightness measurements. This atlas shows that more than 80% of the world and more than 99% of the U.S. and European populations live under light-polluted skies. The Milky Way is hidden from more than one-third of humanity, including 60% of Europeans and nearly 80% of North Americans. Moreover, 23% of the world’s land surfaces between 75°N and 60°S, 88% of Europe, and almost half of the United States experience light-polluted nights. PMID:27386582

Using All-Sky Imaging to Improve Telescope Scheduling (Abstract)

NASA Astrophysics Data System (ADS)

Cole, G. M.

2017-12-01

(Abstract only) Automated scheduling makes it possible for a small telescope to observe a large number of targets in a single night. But when used in areas which have less-than-perfect sky conditions such automation can lead to large numbers of observations of clouds and haze. This paper describes the development of a "sky-aware" telescope automation system that integrates the data flow from an SBIG AllSky340c camera with an enhanced dispatch scheduler to make optimum use of the available observing conditions for two highly instrumented backyard telescopes. Using the minute-by-minute time series image stream and a self-maintained reference database, the software maintains a file of sky brightness, transparency, stability, and forecasted visibility at several hundred grid positions. The scheduling software uses this information in real time to exclude targets obscured by clouds and select the best observing task, taking into account the requirements and limits of each instrument.

Tropospheric haze and colors of the clear twilight sky.

PubMed

Lee, Raymond L; Mollner, Duncan C

2017-07-01

At the earth's surface, clear-sky colors during civil twilights depend on the combined spectral effects of molecular scattering, extinction by tropospheric aerosols, and absorption by ozone. Molecular scattering alone cannot produce the most vivid twilight colors near the solar horizon, for which aerosol scattering and absorption are also required. However, less well known are haze aerosols' effects on twilight sky colors at larger scattering angles, including near the antisolar horizon. To analyze this range of colors, we compare 3D Monte Carlo simulations of skylight spectra with hyperspectral measurements of clear twilight skies over a wide range of aerosol optical depths. Our combined measurements and simulations indicate that (a) the purest antisolar twilight colors would occur in a purely molecular, multiple-scattering atmosphere, whereas (b) the most vivid solar-sky colors require at least some turbidity. Taken together, these results suggest that multiple scattering plays an important role in determining the redness of the antitwilight arch.

The new world atlas of artificial night sky brightness.

PubMed

Falchi, Fabio; Cinzano, Pierantonio; Duriscoe, Dan; Kyba, Christopher C M; Elvidge, Christopher D; Baugh, Kimberly; Portnov, Boris A; Rybnikova, Nataliya A; Furgoni, Riccardo

2016-06-01

Artificial lights raise night sky luminance, creating the most visible effect of light pollution-artificial skyglow. Despite the increasing interest among scientists in fields such as ecology, astronomy, health care, and land-use planning, light pollution lacks a current quantification of its magnitude on a global scale. To overcome this, we present the world atlas of artificial sky luminance, computed with our light pollution propagation software using new high-resolution satellite data and new precision sky brightness measurements. This atlas shows that more than 80% of the world and more than 99% of the U.S. and European populations live under light-polluted skies. The Milky Way is hidden from more than one-third of humanity, including 60% of Europeans and nearly 80% of North Americans. Moreover, 23% of the world's land surfaces between 75°N and 60°S, 88% of Europe, and almost half of the United States experience light-polluted nights.

Death of Darkness: Artificial Sky Brightness in the Anthropocene

NASA Astrophysics Data System (ADS)

Zender, C. S.

2016-12-01

Many species (including ours) need darkness to survive and thrive yet light pollution in the anthropocene has received scant attention in Earth System Models (ESMs). Anthropogenic aerosols can brighten background sky brightness and reduce the contrast between skylight and starlight. These are both aesthetic and health-related issues due to their accompanying disruption of circadian rhythms. We quantify aerosol contributions to light pollution using a single-column night sky model, NiteLite, suitable for implementation in ESMs. NiteLite accounts for physiologcal (photopic and scotopic vision, retinal diameter/age), anthropogenic (light and aerosol pollution properties), and natural (surface albedo, trace gases) effects on background brightness and threshold visibility. We find that stratospheric aerosol injection contemplated as a stop-gap measure to counter global warming would increase night-sky brightness by about 25%, and thus eliminate last pristine dark sky areas on Earth. Our results suggest that ESMs incorporate light pollution so that associated societal impacts can be better quantified and included in policy deliberations.

Site comparison for optical visibility statistics in southern Arizona

NASA Technical Reports Server (NTRS)

Cowles, K. A.

1990-01-01

One of the best locations in the continental United States for astronomical telescopes is southern Arizona. The mountains surrounding Tucson have clear skies 80 percent of the year, with image quality generally better than 2 seconds on peaks. Two of the existing observatory sites in this area are being considered as locations for one of the three Atmospheric Visibility Monitoring (AVM) observatories. These sites are Mount Lemmon and Mount Hopkins. A comparison of the characteristics of each of the sites is made here to identify the more desirable of the two locations. It is recommended that Mount Lemmon be selected as the Arizona site for this project.

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

A New Sky Brightness Monitor

NASA Astrophysics Data System (ADS)

Crawford, David L.; McKenna, D.

2006-12-01

A good estimate of sky brightness and its variations throughout the night, the months, and even the years is an essential bit of knowledge both for good observing and especially as a tool in efforts to minimize sky brightness through local action. Hence a stable and accurate monitor can be a valuable and necessary tool. We have developed such a monitor, with the financial help of Vatican Observatory and Walker Management. The device is now undergoing its Beta test in preparation for production. It is simple, accurate, well calibrated, and automatic, sending its data directly to IDA over the internet via E-mail . Approximately 50 such monitors will be ready soon for deployment worldwide including most major observatories. Those interested in having one should enquire of IDA about details.

Gaia, an all-sky survey for standard photometry

NASA Astrophysics Data System (ADS)

Carrasco, J. M.; Weiler, M.; Jordi, C.; Fabricius, C.

2017-03-01

Gaia ESA's space mission (launched in 2013) includes two low resolution spectroscopic instruments (one in the blue, BP, and another in the red, RP, wavelength domains) to classify and derive the astrophysical parameters of the observed sources. As it is well known, Gaia is a full-sky unbiased survey down to about 20th magnitude. The scanning law yields a rather uniform coverage of the sky over the full extent (a minimum of 5 years) of the mission. Gaia data reduction is a global one over the full mission. Both sky coverage and data reduction strategy ensure an unprecedented all-sky homogeneous spectrophotometric survey. Certainly, that survey is of interest for current and future on-ground and space projects, like LSST, PLATO, EUCLID and J-PAS/J-PLUS among others. These projects will benefit from the large amount (more than one billion) and wide variety of objects observed by Gaia with good quality spectrophotometry. Synthetic photometry derived from Gaia spectrophotometry for any passband can be used to expand the set of standard sources for these new instruments to come. In the current Gaia data release scenario, BP/RP spectrophotometric data will be available in the third release (in 2018, TBC). Current preliminary results allow us to estimate the precision of synthetic photometry derived from the Gaia data. This already allows the preparation of the on-going and future surveys and space missions. We discuss here the exploitation of the Gaia spectrophotometry as standard reference due to its full-sky coverage and its expected photometric uncertainties derived from the low resolution Gaia spectra.

The Quiet Skies Project

ERIC Educational Resources Information Center

Rapp, Steve

2008-01-01

To help promote student awareness of the connection between radio astronomy and radio frequency interference (RFI), an inquiry-based science curriculum was developed to allow high school students to determine RFI levels in their communities. The Quiet Skies Project--the result of a collaboration between the National Aeronautics and Space…

LEE VINING INTAKE LOOKING SOUTH. (MOTTLED SKY FROM CONDENSED MOISTURE ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

LEE VINING INTAKE LOOKING SOUTH. (MOTTLED SKY FROM CONDENSED MOISTURE ON NEGATIVE AFFECTING EVEN PROCESSING OF SKY, SAVED FOR DOCUMENTARY PURPOSES) - Los Angeles Aqueduct, Lee Vining Intake Structure, Los Angeles, Los Angeles County, CA

Artificial light alters natural regimes of night-time sky brightness

PubMed Central

Davies, Thomas W.; Bennie, Jonathan; Inger, Richard; Gaston, Kevin J.

2013-01-01

Artificial light is globally one of the most widely distributed forms of anthropogenic pollution. However, while both the nature and ecological effects of direct artificial lighting are increasingly well documented, those of artificial sky glow have received little attention. We investigated how city lights alter natural regimes of lunar sky brightness using a novel ten month time series of measurements recorded across a gradient of increasing light pollution. In the city, artificial lights increased sky brightness to levels six times above those recorded in rural locations, nine and twenty kilometers away. Artificial lighting masked natural monthly and seasonal regimes of lunar sky brightness in the city, and increased the number and annual regime of full moon equivalent hours available to organisms during the night. The changes have potentially profound ecological consequences.

A DIPOLE ON THE SKY: PREDICTIONS FOR HYPERVELOCITY STARS FROM THE LARGE MAGELLANIC CLOUD

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

Boubert, Douglas; Evans, N. Wyn, E-mail: d.boubert@ast.cam.ac.uk, E-mail: nwe@ast.cam.ac.uk

2016-07-01

We predict the distribution of hypervelocity stars (HVSs) ejected from the Large Magellanic Cloud (LMC), under the assumption that the dwarf galaxy hosts a central massive black hole (MBH). For the majority of stars ejected from the LMC, the orbital velocity of the LMC has contributed a significant fraction of their galactic rest-frame velocity, leading to a dipole density distribution on the sky. We quantify the dipole using spherical harmonic analysis and contrast with the monopole expected for HVSs ejected from the Galactic center (GC). There is a tendril in the density distribution that leads the LMC, which is coincidentmore » with the well-known and unexplained clustering of HVSs in the constellations of Leo and Sextans. Our model is falsifiable since it predicts that Gaia will reveal a large density of HVSs in the southern hemisphere.« less

Suberythemal Sun Exposures at Swedish Schools Depend on Sky Views of the Outdoor Environments - Possible Implications for Pupils' Health.

PubMed

Pagels, Peter; Wester, Ulf; Söderström, Margareta; Lindelöf, Bernt; Boldemann, Cecilia

2016-01-01

More scheduled outdoor stay is increasingly advocated for school children. This study measured 2(nd) , 5(th) and 8(th) graders' erythemal UV-exposure in September, March and May at four Swedish schools. We related those exposures, as fractions of total available ambient radiation, to the schools outdoor environments differing in amount of shade, vegetation, and peripheral city-scape quantified as percentage of free sky view calculated from fish-eye photographs. Exposures correlated with the sky views (with exceptions in May) and were suberythemal. The exposures were also below the threshold limit of the International Commission on Non-Ionizing Radiation Protection (ICNIRP) for hazard evaluation of UVR but were potentially enough for adequate vitamin D formation according to a cited model calculation - as illustrated in the results and discussed. The school environments, typical in southern and middle Sweden, offer enough shade to protect children from overexposure during seasons with potentially harmful solar UV radiation. Pupils' outdoor stay may be extended during September and March. In May extended outdoor stay of the youngest pupils requires a more UVR-protective environment. © 2015 The American Society of Photobiology.

Impact of a Saharan dust intrusion over southern Spain on DNI estimation with sky cameras

NASA Astrophysics Data System (ADS)

Alonso-Montesinos, J.; Barbero, J.; Polo, J.; López, G.; Ballestrín, J.; Batlles, F. J.

2017-12-01

To operate Central Tower Solar Power (CTSP) plants properly, solar collector systems must be able to work under varied weather conditions. Therefore, knowing the state of the atmosphere, and more specifically the level of incident radiation, is essential operational information to adapt the electricity production system to atmospheric conditions. In this work, we analyze the impact of a strong Saharan dust intrusion on the Direct normal irradiance (DNI) registered at two sites 35 km apart in southeastern Spain: the University of Almería (UAL) and the Plataforma Solar de Almería (PSA). DNI can be inputted into the European Solar Radiation Atlas (ESRA) clear sky procedure to derive Linke turbidity values, which proved to be extremely high at the UAL. By using the Simple Model of the Atmospheric Radiative Transfer of Sunshine (SMARTS) at the PSA site, AERONET data from PSA and assuming dust dominated aerosol, DNI estimations agreed strongly with the measured DNI values. At the UAL site, a SMARTS simulation of the DNI values also seemed to be compatible with dust dominated aerosol.

Improving precision of Pi of the Sky photometric measurements

NASA Astrophysics Data System (ADS)

Siudek, M.; Małek, K.; Mankiewicz, L.; Opiela, R.; Sokołowski, M.; Źarnecki, A. F.

Pi of the Sky is a system of robotic telescopes designed for observations of short timescale astrophysical phenomena, like prompt optical GRB emission. The apparatus is designed to monitor a large fraction of the sky with 12^{m} - 13^{m} range and time resolution of the order of 1, 10 seconds. All measurements taken by the Pi of the Sky detector located in Las Campanas Observatory (LCO) in Chile are available on the Pi of the Sky website through a dedicated interface which also allows to download the selected data. Pi of the Sky database from period 2006 - 2009 contains more than 2 billions measurements of almost 17 millions of objects. In order to facilitate analysis of variable stars we have developed a system of dedicated filters to remove bad measurements or frames. They are needed to remove measurements affected by detector imperfections (hot pixels, measurement close to CCD edge, background due to opened shutter) or observation conditions (planet or planetoid passage, moon halo). With approximate color calibration algorithm taking into account appropriate corrections based on the spectral type of reference stars the photometry algorithm can be improved further. This process is illustrated by the analysis of the BG Ind system where we have been able to reduce the total systematic uncertainty to about 0.05 magnitudes.

76 FR 42704 - Sky River LLC; Notice of Filing

Federal Register 2010, 2011, 2012, 2013, 2014

2011-07-19

... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Docket Nos. ER11-3277-000; ER11-3277-001] Sky River LLC; Notice of Filing Take notice that, on July 8, 2011, Sky River LLC filed to amend its Open Access Transmission Tariff (OATT) filing, submitted on April 1, 2011 and amended on April 7...

Gender Roles and Night-Sky Watching among College Students

ERIC Educational Resources Information Center

Kelly, William E.; McGee, Catherine M.

2012-01-01

The present study investigated the relationship between gender roles and night-sky watching in a sample of college students (N=161). The Bem Sex-Role Inventory (BSRI) and the Noctcaelador Inventory (NI) were used to investigate the differences between gender role groups for night-sky watching. The results supported the hypothesis that androgynous…

Microwave Sky image from the WMAP Mission

NASA Technical Reports Server (NTRS)

2005-01-01

A detailed full-sky map of the oldest light in the universe. It is a 'baby picture' of the universe. Colors indicate 'warmer' (red) and 'cooler' (blue) spots. The oval shape is a projection to display the whole sky; similar to the way the globe of the earth can be projected as an oval. The microwave light captured in this picture is from 379,000 years after the Big Bang, over 13 billion years ago. For more information, see http://map.gsfc.nasa.gov/m_mm/mr_whatsthat.html

The Big Sky inside

ERIC Educational Resources Information Center

Adams, Earle; Ward, Tony J.; Vanek, Diana; Marra, Nancy; Hester, Carolyn; Knuth, Randy; Spangler, Todd; Jones, David; Henthorn, Melissa; Hammill, Brock; Smith, Paul; Salisbury, Rob; Reckin, Gene; Boulafentis, Johna

2009-01-01

The University of Montana (UM)-Missoula has implemented a problem-based program in which students perform scientific research focused on indoor air pollution. The Air Toxics Under the Big Sky program (Jones et al. 2007; Adams et al. 2008; Ward et al. 2008) provides a community-based framework for understanding the complex relationship between poor…

Gods, Demons and Deceivers: Jesuits Facing Chaco Skies

NASA Astrophysics Data System (ADS)

López, Alejandro Martín

2015-05-01

The Jesuit missions located in the Chaco are less known than the ones in Paraguay. They are the last step of the Jesuits' missionary device in the Rio de la Plata region. They were dedicated to 'evangelize' and 'civilize' the aboriginal groups considered more hostile: nomadic hunter-gatherers who adopted the use of horses and were not controlled by the colonial government. These groups were seen by Europeans as a radical otherness. That is why the Jesuits' descriptions of Chaco Indian skies are a very interesting example about European attitudes toward other worldviews. This paper explores the use of different paradigms for interpreting these alternative skies: demonic influence, the deception of sorcerers and an Evemeristic reading of the indigenous worldview. This article also addresses some of the interactions between the aboriginal and Christian skies in the mission context.

Proof of Concept for a Simple Smartphone Sky Monitor

NASA Astrophysics Data System (ADS)

Kantamneni, Abhilash; Nemiroff, R. J.; Brisbois, C.

2013-01-01

We present a novel approach of obtaining a cloud and bright sky monitor by using a standard smartphone with a downloadable app. The addition of an inexpensive fisheye lens can extend the angular range to the entire sky visible above the device. A preliminary proof of concept image shows an optical limit of about visual magnitude 5 for a 70-second exposure. Support science objectives include cloud monitoring in a manner similar to the more expensive cloud monitors in use at most major astronomical observatories, making expensive observing time at these observatories more efficient. Primary science objectives include bright meteor tracking, bright comet tracking, and monitoring the variability of bright stars. Citizen science objectives include crowd sourcing of many networked sky monitoring smartphones typically in broader support of many of the primary science goals. The deployment of a citizen smartphone array in an active science mode could leverage the sky monitoring data infrastructure to track other non-visual science opportunities, including monitoring the Earth's magnetic field for the effects of solar flares and exhaustive surface coverage for strong seismic events.

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.

AmeriFlux US-SO3 Sky Oaks- Young Stand

DOE Data Explorer

Oechel, Walt [San Diego State University

2016-01-01

This is the AmeriFlux version of the carbon flux data for the site US-SO3 Sky Oaks- Young Stand. Site Description - The Sky Oaks Young site is located near the Sky Oaks Field station, owned and operated by San Diego State University. Chaparral vegetation, associated with a Mediterranean climate, covers nearly half of the rough and rocky terrain. Precipitation is almost exclusively confined to the winter months. During the summer and early fall, hot and dry Santa Ana winds from the northeast bring desert heat to the site. A high intensity natural wildfire occurred in July of 2003. The stand age at the time of the wildfire was 10 years old, following a controlled burn in 1993.

Twilight and Daytime Colors of the Clear Sky

DTIC Science & Technology

1994-07-20

greatly, with some surprising consequences for their calorimetric gamuts . Key words: Atmospheric optics, clear-sky chromaticities, blue sky, twilight...First we calculate a chromaticity curve’s unnormal- ized clorimetric gamut g by finding the curve’s average chromaticity [here, its mean CIE (Commis...calorimetric gamut , g. Taking the spectrum locus as an upper limit on color gamut , we use its gamut to normalize any other chromaticity 20 July 1994 / Vol

Direct and semidirect aerosol effects of southern African biomass burning aerosol

NASA Astrophysics Data System (ADS)

Sakaeda, Naoko; Wood, Robert; Rasch, Philip J.

2011-06-01

Direct and semidirect radiative effects of biomass burning aerosols from southern African fires during July-October are investigated using 20 year runs of the Community Atmospheric Model (CAM) coupled to a slab ocean model. Aerosol optical depth is constrained using observations in clear skies from Moderate Resolution Imaging Spectroradiometer (MODIS) and for aerosol layers above clouds from Cloud Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO). Over the ocean, where the aerosol layers are primarily located above cloud, negative top of atmosphere (TOA) semidirect radiative effects associated with increased low cloud cover dominate over a weaker positive all-sky direct radiative effect (DRE). In contrast, over the land where the aerosols are often below or within cloud layers, reductions in cloud liquid water path (LWP) lead to a positive semidirect radiative effect that dominates over a near-zero DRE. Over the ocean, the cloud response can be understood as a response to increased lower tropospheric stability (LTS) which is caused both by radiative heating in overlying layers and surface cooling in response to direct aerosol forcing. The marine cloud changes are robust to changes in the cloud parameterization (removal of the hard-wired dependence of clouds on LTS), suggesting that they are physically realistic. Over land, decreased LWP is consistent with weaker convection driven by increased static stability. Over the entire region the overall TOA radiative effect from the biomass burning aerosols is almost zero due to opposing effects over the land and ocean. However, the surface forcing is strongly negative, which leads to a reduction in precipitation and also a reduction in sensible heat flux. The former is primarily realized through reductions in convective precipitation on both the southern and northern flanks of the convective precipitation region spanning the equatorial rain forest and the Intertropical Convergence Zone (ITCZ) in the

The Millimeter Sky Transparency Imager (MiSTI)

NASA Astrophysics Data System (ADS)

Tamura, Yoichi; Kawabe, Ryohei; Kohno, Kotaro; Fukuhara, Masayuki; Momose, Munetake; Ezawa, Hajime; Kuboi, Akihito; Sekiguchi, Tomohiko; Kamazaki, Takeshi; Vila-Vilaró, Baltasar; Nakagawa, Yuki; Okada, Norio

2011-04-01

The Millimeter Sky Transparency Imager (MiSTI) is a small millimeter-wave scanning telescope with a 25-cm diameter dish operating at 183 GHz. MiSTI is installed at Atacama, Chile, and it measures emission from atmospheric water vapor and its fluctuations to estimate atmospheric absorption in the millimeter to submillimeter range. MiSTI observes the water vapor distribution at a spatial resolution of 0.°5, and it is sensitive enough to detect an excess path length of lesssim0.05 mm for an integration time of 1 s. By comparing the MiSTI measurements with those by a 220 GHz tipper, we validated that the 183 GHz measurements of MiSTI are correct, down to the level of any residual systematic errors in the 220 GHz measurements. Since 2008, MiSTI has provided real-time (every 1 hr) monitoring of the all-sky opacity distribution and atmospheric transmission curves in the (sub)millimeter through the internet, allowing us to know the (sub)millimeter sky conditions at Atacama.

Design Analysis of Corridors-in-the-Sky

NASA Technical Reports Server (NTRS)

Xue, Min

2008-01-01

Corridors-in-the-sky or tubes is one of new concepts in dynamic airspace configuration. It accommodates high density traffic, which has similar trajectories. Less air traffic controllers workload is expected than classic airspaces, thus, corridors-in-the-sky may increase national airspace capacity and reduce flight delays. To design corridors-in-the-sky, besides identifying their locations, their utilization, altitudes, and impacts on remaining system need to be analyzed. This paper chooses one tube candidate and presents analyses of spatial and temporal utilization of the tube, the impact on the remaining traffic, and the potential benefit caused by off-loading the traffic from underlying sectors. Fundamental issues regarding to the benefits have been also clarified. Methods developed to assist the analysis are described. Analysis results suggest dynamic tubes in terms of varied utilizations during different time periods. And it is found that combined lane options would be a good choice to lower the impact on non-tube users. Finally, it shows significant reduction of peak aircraft count in underlying sectors with only one tube enabled.

Introduction to the Arizona Sky Island Arthropod Project (ASAP): Systematics, Biogeography, Ecology, and Population Genetics of Arthropods of the Madrean Sky Islands.

PubMed

Moore, Wendy; Meyer, Wallace M; Eble, Jeffrey A; Franklin, Kimberly; Wiens, John F; Brusca, Richard C

2013-01-01

The Arizona Sky Island Arthropod Project (ASAP) is a new multi-disciplinary research program at the University of Arizona that combines systematics, biogeography, ecology, and population genetics to study origins and patterns of arthropod diversity along elevation gradients and among mountain ranges in the Madrean Sky Island Region. Arthropods represent taxonomically and ecologically diverse organisms that drive key ecosystem processes in this mountain archipelago. Using data from museum specimens and specimens we obtain during long-term collecting and monitoring programs, ASAP will document arthropod species across Arizona's Sky Islands to address a number of fundamental questions about arthropods of this region. Baseline data will be used to determine climatic boundaries for target species, which will then be integrated with climatological models to predict future changes in arthropod communities and distributions in the wake of rapid climate change. ASAP also makes use of the natural laboratory provided by the Sky Islands to investigate ecological and genetic factors that influence diversification and patterns of community assembly. Here, we introduce the project, outline overarching goals, and describe preliminary data from the first year of sampling ground-dwelling beetles and ants in the Santa Catalina Mountains.

Introduction to the Arizona Sky Island Arthropod Project (ASAP): Systematics, Biogeography, Ecology, and Population Genetics of Arthropods of the Madrean Sky Islands

PubMed Central

Moore, Wendy; Meyer, Wallace M.; Eble, Jeffrey A.; Franklin, Kimberly; Wiens, John F.; Brusca, Richard C.

2014-01-01

The Arizona Sky Island Arthropod Project (ASAP) is a new multi-disciplinary research program at the University of Arizona that combines systematics, biogeography, ecology, and population genetics to study origins and patterns of arthropod diversity along elevation gradients and among mountain ranges in the Madrean Sky Island Region. Arthropods represent taxonomically and ecologically diverse organisms that drive key ecosystem processes in this mountain archipelago. Using data from museum specimens and specimens we obtain during long-term collecting and monitoring programs, ASAP will document arthropod species across Arizona's Sky Islands to address a number of fundamental questions about arthropods of this region. Baseline data will be used to determine climatic boundaries for target species, which will then be integrated with climatological models to predict future changes in arthropod communities and distributions in the wake of rapid climate change. ASAP also makes use of the natural laboratory provided by the Sky Islands to investigate ecological and genetic factors that influence diversification and patterns of community assembly. Here, we introduce the project, outline overarching goals, and describe preliminary data from the first year of sampling ground-dwelling beetles and ants in the Santa Catalina Mountains. PMID:25505938

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 16Sky Survey. Information available at http://www.sdss.org.

Explanatory Supplement to the WISE All-Sky Release Products

NASA Technical Reports Server (NTRS)

2012-01-01

The Wide-field Infrared Survey Explorer (WISE; Wright et al. 2010) surveyed the entire sky at 3.4, 4.6, 12 and 22 microns in 2010, achieving 5-sigma point source sensitivities per band better than 0.08, 0.11, 1 and 6 mJy in unconfused regions on the ecliptic. The WISE All-Sky Data Release, conducted on March 14, 2012, incorporates all data taken during the full cryogenic mission phase, 7 January 2010 to 6 August 20l0,that were processed with improved calibrations and reduction algorithms. Release data products include: (1) an Atlas of 18,240 match-filtered, calibrated and coadded image sets; (2) a Source Catalog containing positions and four-band photometry for over 563 million objects, and (3) an Explanatory Supplement. Ancillary products include a Reject Table that contains 284 million detections that were not selected for the Source Catalog because they are low signal-to-noise ratio or spurious detections of image artifacts, an archive of over 1.5 million sets of calibrated WISE Single-exposure images, and a database of 9.4 billion source extractions from those single images, and moving object tracklets identified by the NEOWISE program (Mainzer et aI. 2011). The WISE All-Sky Data Release products supersede those from the WISE Preliminary Data Release (Cutri et al. 2011). The Explanatory Supplement to the WISE All-Sky Data Release Products is a general guide for users of the WISE data. The Supplement contains an overview of the WISE mission, facilities, and operations, a detailed description of WISE data processing algorithms, a guide to the content and formals of the image and tabular data products, and cautionary notes that describe known limitations of the All-Sky Release products. Instructions for accessing the WISE data products via the services of the NASA/IPAC Infrared Science Archive are provided. The Supplement also provides analyses of the achieved sky coverage, photometric and astrometric characteristics and completeness and reliability of the All-Sky

``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/.

Identification of periods of clear sky irradiance in time series of GHI measurements

DOE PAGES

Reno, Matthew J.; Hansen, Clifford W.

2016-01-18

In this study, we present a simple algorithm for identifying periods of time with broadband global horizontal irradiance (GHI) similar to that occurring during clear sky conditions from a time series of GHI measurements. Other available methods to identify these periods do so by identifying periods with clear sky conditions using additional measurements, such as direct or diffuse irradiance. Our algorithm compares characteristics of the time series of measured GHI with the output of a clear sky model without requiring additional measurements. We validate our algorithm using data from several locations by comparing our results with those obtained from amore » clear sky detection algorithm, and with satellite and ground-based sky imagery.« less

Identification of periods of clear sky irradiance in time series of GHI measurements

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

Reno, Matthew J.; Hansen, Clifford W.

In this study, we present a simple algorithm for identifying periods of time with broadband global horizontal irradiance (GHI) similar to that occurring during clear sky conditions from a time series of GHI measurements. Other available methods to identify these periods do so by identifying periods with clear sky conditions using additional measurements, such as direct or diffuse irradiance. Our algorithm compares characteristics of the time series of measured GHI with the output of a clear sky model without requiring additional measurements. We validate our algorithm using data from several locations by comparing our results with those obtained from amore » clear sky detection algorithm, and with satellite and ground-based sky imagery.« less

BlueSky Cloud Framework: An E-Learning Framework Embracing Cloud Computing

NASA Astrophysics Data System (ADS)

Dong, Bo; Zheng, Qinghua; Qiao, Mu; Shu, Jian; Yang, Jie

Currently, E-Learning has grown into a widely accepted way of learning. With the huge growth of users, services, education contents and resources, E-Learning systems are facing challenges of optimizing resource allocations, dealing with dynamic concurrency demands, handling rapid storage growth requirements and cost controlling. In this paper, an E-Learning framework based on cloud computing is presented, namely BlueSky cloud framework. Particularly, the architecture and core components of BlueSky cloud framework are introduced. In BlueSky cloud framework, physical machines are virtualized, and allocated on demand for E-Learning systems. Moreover, BlueSky cloud framework combines with traditional middleware functions (such as load balancing and data caching) to serve for E-Learning systems as a general architecture. It delivers reliable, scalable and cost-efficient services to E-Learning systems, and E-Learning organizations can establish systems through these services in a simple way. BlueSky cloud framework solves the challenges faced by E-Learning, and improves the performance, availability and scalability of E-Learning systems.

Simplified Night Sky Display System

NASA Technical Reports Server (NTRS)

Castellano, Timothy P.

2010-01-01

A document describes a simple night sky display system that is portable, lightweight, and includes, at most, four components in its simplest configuration. The total volume of this system is no more than 10(sup 6) cm(sup 3) in a disassembled state, and weighs no more than 20 kilograms. The four basic components are a computer, a projector, a spherical light-reflecting first surface and mount, and a spherical second surface for display. The computer has temporary or permanent memory that contains at least one signal representing one or more images of a portion of the sky when viewed from an arbitrary position, and at a selected time. The first surface reflector is spherical and receives and reflects the image from the projector onto the second surface, which is shaped like a hemisphere. This system may be used to simulate selected portions of the night sky, preserving the appearance and kinesthetic sense of the celestial sphere surrounding the Earth or any other point in space. These points will then show motions of planets, stars, galaxies, nebulae, and comets that are visible from that position. The images may be motionless, or move with the passage of time. The array of images presented, and vantage points in space, are limited only by the computer software that is available, or can be developed. An optional approach is to have the screen (second surface) self-inflate by means of gas within the enclosed volume, and then self-regulate that gas in order to support itself without any other mechanical support.

Redundant Calibration: breaking the constraints of limited sky information

NASA Astrophysics Data System (ADS)

Joseph, Ronniy C.

2018-05-01

The latest generation of low frequency radio interferometers, e.g. LOFAR, MWA, PAPER, has been pushing down the detection limits on the hydrogen signal from the Epoch of Reionisation. However, due to the challenges posed by foregrounds and instrumental systematics the signal has eluded detection thus far. To overcome these challenges we require a detailed understanding of the calibration of these relatively new telescopes. This led to a renewed interest in redundant calibration. Classical calibration schemes depend on sky models based on limited knowledge of the low frequency sky. Redundant calibration, however, allows us to escape our ignorance as it is sky model independent. We will review the field of redundant calibration, and present work we have undertaken to understand the limitations of this calibration method.

The use of a laser ceilometer for sky condition determination

NASA Astrophysics Data System (ADS)

Nadolski, Vickie L.; Bradley, James T.

The use of a laser ceilometer for determining sky condition is presented, with emphasis on the operation of the ceilometer, the sky-condition-reporting algorithm, and how the laser ceilometer and the sky-condition algorithm are used to give a report suitable for aircraft operations and meteorological application. The sampling and processing features of the Vaisala ceilometer produced a detailed and accurate cloud base 'signature' by taking 254 measurement samples of the energy scattered back from a single laser pulse as the pulse traveled from the surface to 12,000 ft. The transmit time from the projection of the laser pulse to its backscattering from a cloud element and subsequent return to a collocated receiver is measured and a cloud height element computed. Attention is given to the development of a vertical visibility concept and of a vertical-visibility algorithm, as well as the strengths and limitations of the sky condition report.

Pi of the Sky full system and the new telescope

NASA Astrophysics Data System (ADS)

Mankiewicz, L.; Batsch, T.; Castro-Tirado, A.; Czyrkowski, H.; Cwiek, A.; Cwiok, M.; Dabrowski, R.; Jelínek, M.; Kasprowicz, G.; Majcher, A.; Majczyna, A.; Malek, K.; Nawrocki, K.; Obara, L.; Opiela, R.; Piotrowski, L. W.; Siudek, M.; Sokolowski, M.; Wawrzaszek, R.; Wrochna, G.; Zaremba, M.; Żarnecki, A. F.

2014-12-01

The Pi of the Sky is a system of wide field of view robotic telescopes, which search for short timescale astrophysical phenomena, especially for prompt optical GRB emission. The system was designed for autonomous operation, monitoring a large fraction of the sky to a depth of 12(m}-13({m)) and with time resolution of the order of 1 - 10 seconds. The system design and observation strategy were successfully tested with a prototype detector operational at Las Campanas Observatory, Chile from 2004-2009 and moved to San Pedro de Atacama Observatory in March 2011. In October 2010 the first unit of the final Pi of the Sky detector system, with 4 CCD cameras, was successfully installed at the INTA El Arenosillo Test Centre in Spain. In July 2013 three more units (12 CCD cameras) were commissioned and installed, together with the first one, on a new platform in INTA, extending sky coverage to about 6000 square degrees.

All-sky brightness monitoring of light pollution with astronomical methods.

PubMed

Rabaza, O; Galadí-Enríquez, D; Estrella, A Espín; Dols, F Aznar

2010-06-01

This paper describes a mobile prototype and a protocol to measure light pollution based on astronomical methods. The prototype takes three all-sky images using BVR filters of the Johnson-Cousins astronomical photometric system. The stars are then identified in the images of the Hipparcos and General Catalogue of Photometric Data II astronomical catalogues, and are used as calibration sources. This method permits the measurement of night-sky brightness and facilitates an estimate of which fraction is due to the light up-scattered in the atmosphere by a wide variety of man-made sources. This is achieved by our software, which compares the sky background flux to that of many stars of known brightness. The reduced weight and dimensions of the prototype allow the user to make measurements from virtually any location. This prototype is capable of measuring the sky distribution of light pollution, and also provides an accurate estimate of the background flux at each photometric band. (c) 2010 Elsevier Ltd. All rights reserved.

Status of the NASA SETI Sky Survey microwave observing project

NASA Technical Reports Server (NTRS)

Klein, M. J.; Gulkis, S.; Wilck, H. C.; Olsen, E. T.; Garyantes, M. F.; Burns, D. J.; Asmar, P. R.; Brady, R. B.; Deich, W. T. S.; Renzetti, N. A.

1992-01-01

The Sky Survey observing program is one of two complementary strategies that NASA plans to use in its microwave Search for Extraterrestrial Intelligence (SETI). The primary objective of the Sky Survey is to search the entire sky over the frequency range 1000-10,000 MHz for evidence of narrow band signals of extraterrestrial, intelligent origin. Spectrum analyzers with upwards of 10 million channels and data rates in excess of 10 gigabits per second are required to complete the survey in less than 7 years. To lay the foundation for the operational SETI Sky Survey, a prototype system has been built to test and refine real time signal detection algorithms, to test scan strategies and observatory control functions, and to test algorithms designed to reject radio frequency interference. This paper presents a high level description of the prototype hardware and reports on the preparations to deploy the system to the 34-m antenna at the research and development station of NASA's Deep Space Communication Complex, Goldstone, California.

ACS/WFC Sky Flats from Frontier Fields Imaging

NASA Astrophysics Data System (ADS)

Mack, J.; Lucas, R. A.; Grogin, N. A.; Bohlin, R. C.; Koekemoer, A. M.

2018-04-01

Parallel imaging data from the HST Frontier Fields campaign (Lotz et al. 2017) have been used to compute sky flats for the ACS/WFC detector in order to verify the accuracy of the current set of flat field reference files. By masking sources and then co-adding many deep frames, the F606W and F814W filters have enough combined background signal that from Poisson statistics are <1% per pixel. In these two filters, the sky flats show spatial residuals 1% or less. These residuals are similar in shape to the WFC flat field 'donut' pattern, in which the detector quantum efficiency tracks the thickness of the two WFC chips. Observations of blue and red calibration standards measured at various positions on the detector (Bohlin et al. 2017) confirm the fidelity of the F814W flat, with aperture photometry consistent to 1% across the FOV, regardless of spectral type. At bluer wavelengths, the total sky background is substantially lower, and the F435W sky flat shows a combination of both flat errors and detector artifacts. Aperture photometry of the red standard star shows a maximum deviation of 1.4% across the array in this filter. Larger residuals up to 2.5% are found for the blue standard, suggesting that the spatial sensitivity in F435W depends on spectral type.

September in the Skies

ERIC Educational Resources Information Center

Riddle, Bob

2004-01-01

This school year begins with no planets visible in the evenings, and it will remain this way until November when Mercury returns to the evening skies. For a period of several days, starting on September 8, you can follow the waning crescent Moon in the early morning as it passes Saturn, Venus, the bright star Regulus, and Mercury. On the morning…

Sky brightness and twilight measurements at Jogyakarta city, Indonesia

NASA Astrophysics Data System (ADS)

Herdiwijaya, Dhani

2016-11-01

The sky brightness measurements were performed using a portable photometer. A pocket-sized and low-cost photometer has 20 degree area measurement, and spectral ranges between 320-720 nm with output directly in magnitudes per arc second square (mass) unit. The sky brightness with 3 seconds temporal resolutions was recorded at Jogyakarta city (110° 25’ E; 70° 52’ S; elevation 100 m) within 136 days in years from 2014 to 2016. The darkest night could reach 22.61 mpass only in several seconds, with mean value 18.8±0.7 mpass and temperature variation 23.1±1.2 C. The difference of mean sky brightness between before and after midnight was about -0.76 mpass or 2.0 times brighter. Moreover, the sky brightness and temperature fluctuations were more stable in after midnight than in before midnight. It is suggested that city light pollution affects those variations, and subsequently duration of twilight. By comparing twilight brightness for several places, we also suggest a 17° solar dip or about 66 minutes before sunrise for new time of Fajr prayer.

[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.

Analysis of photosynthetically active radiation under various sky conditions in Wuhan, Central China.

PubMed

Wang, Lunche; Gong, Wei; Lin, Aiwen; Hu, Bo

2014-10-01

Observations of photosynthetically active radiation (PAR) and global solar radiation (G) at Wuhan, Central China during 2005-2012 were first reported to investigate PAR variability at different time scales and its PAR fraction (F(p)) under different sky conditions. Both G irradiances (I(g)) and PAR irradiances (I(p)) showed similar seasonal features that peaked in values at noon during summer and reached their lower values in winter. F(p) reached higher values during either sunrise or sunset; lower values of F p appeared at local noon because of the absorption effects of water vapor and clouds on long-wave radiation. There was an inverse relationship between clearness index (K(t)) and F(p); the maximum I(p) decreased by 22.3 % (39.7 %) when sky conditions changed from overcast to cloudless in summer (winter); solar radiation was more affected by cloudiness than the seasonal variation in cloudy skies when compared with that in clear skies. The maximum daily PAR irradiation (R(p)) was 11.89 MJ m⁻² day⁻¹ with an annual average of 4.85 MJ m⁻² day⁻¹. F p was in the range of 29-61.5 % with annual daily average value being about 42 %. Meanwhile, hourly, daily, and monthly relationships between R p and G irradiation (R g) under different sky conditions were investigated. It was discovered that cloudy skies were the dominated sky condition in this region. Finally, a clear-sky PAR model was developed by analyzing the dependence of PAR irradiances on optical air mass under various sky conditions for the whole study period in Central China, which will lay foundations for ecological process study in the near future.

Flat-Sky Pseudo-Cls Analysis for Weak Gravitational Lensing

NASA Astrophysics Data System (ADS)

Asgari, Marika; Taylor, Andy; Joachimi, Benjamin; Kitching, Thomas D.

2018-05-01

We investigate the use of estimators of weak lensing power spectra based on a flat-sky implementation of the 'Pseudo-CI' (PCl) technique, where the masked shear field is transformed without regard for masked regions of sky. This masking mixes power, and 'E'-convergence and 'B'-modes. To study the accuracy of forward-modelling and full-sky power spectrum recovery we consider both large-area survey geometries, and small-scale masking due to stars and a checkerboard model for field-of-view gaps. The power spectrum for the large-area survey geometry is sparsely-sampled and highly oscillatory, which makes modelling problematic. Instead, we derive an overall calibration for large-area mask bias using simulated fields. The effects of small-area star masks can be accurately corrected for, while the checkerboard mask has oscillatory and spiky behaviour which leads to percent biases. Apodisation of the masked fields leads to increased biases and a loss of information. We find that we can construct an unbiased forward-model of the raw PCls, and recover the full-sky convergence power to within a few percent accuracy for both Gaussian and lognormal-distributed shear fields. Propagating this through to cosmological parameters using a Fisher-Matrix formalism, we find we can make unbiased estimates of parameters for surveys up to 1,200 deg2 with 30 galaxies per arcmin2, beyond which the percent biases become larger than the statistical accuracy. This implies a flat-sky PCl analysis is accurate for current surveys but a Euclid-like survey will require higher accuracy.

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

A Strategy for Urban Astronomical Observatory Site Preservation: The Southern Arizona Example

NASA Astrophysics Data System (ADS)

Craine, Eric R.; Craine, Brian L.; Craine, Patrick R.; Craine, Erin M.; Fouts, Scott

2014-05-01

Urbanized observatories are under financial pressures for numerous and complex reasons, including concerns that increasing sky brightness will continue to erode their scientific viability. The history of urbanized observatories is one of steady decline and divestiture. We argue that light at night (LAN) impacts of urban growth are inadequately understood, that current measurement techniques are incomplete in scope, and that both limit the effectiveness of mitigation programs. We give examples of these factors for Pima County, Arizona, and propose techniques and a program that could provide focus and power to mitigation efforts, and could extend the longevity of southern Arizona observatories.

The Two Micron All Sky Survey

NASA Astrophysics Data System (ADS)

Lonsdale, Carol

The 2 Micron All Sky Survey (2MASS) project, a collaboration between the University of Massachusetts (Dr. Mike Skrutskie, PI) and the Infrared Processing and Analysis Center, JPL/Caltech funded primarily by NASA and the NSF, will scan the entire sky utilizing two new, highly automated 1.3m telescopes at Mt. Hopkins, AZ and at CTIO, Chile. Each telescope simultaneously scans the sky at J, H and Ks with a three channel camera using 256x256 arrays of HgCdTe detectors to detect point sources brighter than about 1 mJy (to SNR=10), with a pixel size of 2.0 arcseconds. The data rate is $\\sim 19$ Gbyte per night, with a total processed data volume of 13 Tbytes of images and 0.5 Tbyte of tabular data. The 2MASS data is archived nightly into the Infrared Science Information System at IPAC, which is based on an Informix database engine, judged at the time of purchase to have the best commercially available indexing and parallelization flexibility, and a 5 Tbyte-capacity RAID multi-threaded disk system with multi-server shared disk architecture. I will discuss the challenges of processing and archiving the 2MASS data, and of supporting intelligent query access to them by the astronomical community across the net, including possibilities for cross-correlation with other remote data sets.

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).

Providing Diurnal Sky Cover Data at ARM Sites

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

Klebe, Dimitri I.

2015-03-06

The Solmirus Corporation was awarded two-year funding to perform a comprehensive data analysis of observations made during Solmirus’ 2009 field campaign (conducted from May 21 to July 27, 2009 at the ARM SGP site) using their All Sky Infrared Visible Analyzer (ASIVA) instrument. The objective was to develop a suite of cloud property data products for the ASIVA instrument that could be implemented in real time and tailored for cloud modelers. This final report describes Solmirus’ research and findings enabled by this grant. The primary objective of this award was to develop a diurnal sky cover (SC) data product utilizingmore » the ASIVA’s infrared (IR) radiometrically-calibrated data and is described in detail. Other data products discussed in this report include the sky cover derived from ASIVA’s visible channel and precipitable water vapor, cloud temperature (both brightness and color), and cloud height inferred from ASIVA’s IR channels.« less

A Regional, Multi-Stakeholder Collaboration for Dark-Sky Protection in Flagstaff, Arizona

NASA Astrophysics Data System (ADS)

Hall, Jeffrey C.

2018-01-01

Flagstaff, Arizona is home to almost $200M in astronomical assets, including Lowell Observatory's 4.3-meter Discovery Channel Telescope and the Navy Precision Optical Interferometer, a partnership of Lowell, the U. S. Naval Observatory, and the Naval Research Laboratory. The City of Flagstaff and surrounding Coconino County have comprehensive and effective dark-sky ordinances, but continued regional growth has the potential to degrade the area's dark skies to a level at which observatory missions could be compromised. As a result, a wide array of stakeholders (the observatories, the City, the County, local dark-sky advocates, the business and tourism communities, the national parks and monuments, the Navajo Nation, the U. S. Navy, and others) have engaged in three complementary efforts to ensure that Flagstaff and Coconino County protect the area's dark skies while meeting the needs of the various communities and providing for continued growth and development. In this poster, I will present the status of Flagstaff's conversion to LED outdoor lighting, the Mission Compatibility Study carried out by the Navy to evaluate the dark-sky effects of buildout in Flagstaff, and the Joint Land Use Study (JLUS) presently underway among all the aforementioned stakeholders. Taken in sum, the efforts represent a comprehensive and constructive approach to dark-sky preservation region-wide, and they show what can be achieved when a culture of dark-sky protection is present and deliberate efforts are undertaken to maintain it for decades to come.

Building on the International Year of Astronomy: The Dark Skies Awareness Program

NASA Astrophysics Data System (ADS)

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

2010-08-01

The International Year of Astronomy (IYA2009) offered opportunities to create exemplary educational programs in astronomy, such as those through the cornerstone project, Dark Skies Awareness (DSA). The preservation of dark skies is important for many reasons including astronomy, energy conservation, wildlife conservation, and even human health. Light pollution is a growing concern, yet it is one of the easiest global environmental problems citizen scientists can address on a local level. The Dark Skies workshop imparted the skills necessary for participants to lead activities at their home institution for conserving dark skies. Workshop participants experienced the hands-on activities, which are suitable for use in a variety of settings including museums, science centers, planetariums, schools, university outreach efforts, and astronomy club events. Participants were immersed in activities that illustrate proper lighting, light pollution's effects on wildlife, and how to measure the darkness of your skies. Several citizen science projects were highlighted, including GLOBE at Night, the Great World Wide Star Count, and How Many Stars. These programs enlist the help of students and the general public to collect data on the night sky conditions in their community and contribute to a worldwide database on light pollution. The data can be analyzed using various online tools. A CD of activities, a light shielding demonstration, a book, a two DVD set with a planetarium show, and many other resources are included in a Dark Skies Education Kit, which workshop participants received at the close of the workshop.

Teach and Touch the Earth and Sky

NASA Astrophysics Data System (ADS)

Florina Tendea, Camelia

2017-04-01

My name is Camelia Florina Tendea. I am primary school teacher at "Horea, Closca and Crisan" Secondary School, in Brad, a town in the west side of Transylvania. I am permanently interested to develop my knowledge and teaching skills about space sciences (Earth and Sky) because the new generations of students are very well informed and couriouse about these topics. In this context the teachers must be prepared to deal with such requests in school. Introducing of activity: For a primary school teacher is a real challenge teaching about Earth and Sky, so I consider that a collaboration with science teachers, engineers and other specialists in the sciences is absolutely essential and beneficial in the educational design. In my opinion, the contents about Earth ans Sky-Space in a single word- are very attractive for students and they are a permanent source of discoveries and provide a multidisciplinary vision, so required in the education. Possible contents to teach in primary school: about Earth: -Terra -the third Planet from the Sun; How Earth spins; Land and water; The Earth seen from space, Trip between Earth and Moon,Weather Phenomena; the Poles; about Sky: Solar System, Asteroids, Comets, Meteorites; Rosetta Mission or rendez-vous with a comet; Sun.Moon. Earth. Eclipse;Light Pollution and protection of the night sky; Life in Space. Astronauts and experiences; Mission X:- Train Like an Astronaut;About ISS. For teachers it is important to know from the beginning how they teach, a viable support is the teaching of STEM subjects, which provides access to careers in astronomy, science/technology space. We could teach about earth and sky using different kinds of experiments, simulations, hands-on activities, competitions, exhibitions, video presentations. Competences developed in primary school through these contents: Comunication, individual studying, understanding and valorisation of scientific information, relating to the natural environment. In addition, they are

The Alphabet and the Sky

NASA Astrophysics Data System (ADS)

Lebeuf, A.

2011-06-01

Since the beginning of the 17th century the letters of the Greek alphabet are used to identify the stars of constellation by order of magnitude. This was simply a practical means of astronomical classification. In several instances the Bible uses such metaphors as "The sky rolled up like a scroll". The idea of associating letters of different alphabets with stars, constellations and the sky in general can be found to day in the marginal subculture. The persistence of such an association of writing with astronomy or cosmology is at least of interest for cultural reasons, but the problem might be of good interest as well for the history of astronomy and cosmology. I present here two examples of this tradition in works of art. The first a painted representation of the Revelation of Saint John in the Orthodox church tradition, and the other in the construction of the late bronze age sacred well at Santa Cristina in Sardinia, Italy.

Eyeing the Sky's Water Vapor

NASA Technical Reports Server (NTRS)

2008-01-01

This image, and many like it, are one way NASA's Phoenix Mars Lander is measuring trace amounts of water vapor in the atmosphere over far-northern Mars. Phoenix's Surface Stereo Imager (SSI) uses solar filters, or filters designed to image the sun, to make these images. The camera is aimed at the sky for long exposures.

SSI took this image as a test on June 9, 2008, which was the Phoenix mission's 15th Martian day, or sol, since landing, at 5:20 p.m. local solar time. The camera was pointed about 38 degrees above the horizon. The white dots in the sky are detector dark current that will be removed during image processing and analysis.

The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space

Mapping the Infrared Sky Artist Concept

NASA Image and Video Library

2009-11-17

This artist conception shows NASA Wide-field Infrared Survey Explorer mapping the whole sky in infrared. The mission will unveil hundreds of thousands of asteroids, and hundreds of millions of stars and galaxies.

Radiative sky cooling: fundamental physics, materials, structures, and applications

NASA Astrophysics Data System (ADS)

Sun, Xingshu; Sun, Yubo; Zhou, Zhiguang; Alam, Muhammad Ashraful; Bermel, Peter

2017-07-01

Radiative sky cooling reduces the temperature of a system by promoting heat exchange with the sky; its key advantage is that no input energy is required. We will review the origins of radiative sky cooling from ancient times to the modern day, and illustrate how the fundamental physics of radiative cooling calls for a combination of properties that may not occur in bulk materials. A detailed comparison with recent modeling and experiments on nanophotonic structures will then illustrate the advantages of this recently emerging approach. Potential applications of these radiative cooling materials to a variety of temperature-sensitive optoelectronic devices, such as photovoltaics, thermophotovoltaics, rectennas, and infrared detectors, will then be discussed. This review will conclude by forecasting the prospects for the field as a whole in both terrestrial and space-based systems.

Image acquisition in the Pi-of-the-Sky project

NASA Astrophysics Data System (ADS)

Jegier, M.; Nawrocki, K.; Poźniak, K.; Sokołowski, M.

2006-10-01

Modern astronomical image acquisition systems dedicated for sky surveys provide large amount of data in a single measurement session. During one session that lasts a few hours it is possible to get as much as 100 GB of data. This large amount of data needs to be transferred from camera and processed. This paper presents some aspects of image acquisition in a sky survey image acquisition system. It describes a dedicated USB linux driver for the first version of the "Pi of The Sky" CCD camera (later versions have also Ethernet interface) and the test program for the camera together with a driver-wrapper providing core device functionality. Finally, the paper contains description of an algorithm for matching several images based on image features, i.e. star positions and their brightness.

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.

Twilight sky brightness measurements as a useful tool for stratospheric aerosol investigations

NASA Astrophysics Data System (ADS)

Mateshvili, Nina; Fussen, Didier; Vanhellemont, Filip; Bingen, Christine; KyröLä, Erkki; Mateshvili, Iuri; Mateshvili, Giuli

2005-05-01

In this paper we demonstrate how twilight sky brightness measurements can be used to obtain information about stratospheric aerosols. Beside this, the measurements of the distribution and the variability of the twilight sky brightness may help to understand how the stratospheric aerosols affect the radiation field, which is important for correct calculations of photodissociation rates. Multispectral measurements of twilight sky brightness were carried out in Abastumani Observatory (41.8°N, 42.8°E), Georgia, South Caucasus, during the period (1991-1993) when the level of stratospheric aerosols was substantially enhanced after the 1991 Mount Pinatubo eruption. The twilight sky brightness was measured at 9 wavelengths (422, 474, 496, 542, 610, 642, 678, 713, and 820 nm) for solar zenith angles from 89° to 107°. There are clear indications of a growth of the stratospheric aerosol layer after the eruption of Mount Pinatubo that manifests itself by "humps" in twilight sky brightness dependences versus solar zenith angle. Similar features were obtained using a radiative transfer code constrained by the SAGE II aerosol optical thicknesses. It is shown how an enhancement of stratospheric aerosol loading perturbs the twilight sky brightness due to light scattering and absorption in the aerosol layer. The influence of ozone variations and background stratospheric aerosols on twilight sky brightness has also been analyzed. The optical thicknesses of the stratospheric aerosol layer obtained from the twilight measurements of 1990-1993 show a good agreement with SAGE II results. The spectral variations of the stratospheric aerosol extinction for pre-Pinatubo and post-Pinatubo measurements reflect the aerosol growth after the eruption. Finally, the utilization of twilight sky brightness measurements for validation of satellite-based measurements of the stratospheric aerosol is proposed.

CFHT's SkyProbe: True Atmospheric Attenuation Measurement in the Telescope Field

NASA Astrophysics Data System (ADS)

Cuillandre, J.-C.; Magnier, E. A.; Isani, S.; Sabin, D.; Knight, W.; Kras, S.; Lai, K.

Developed at the Canada France Hawaii Telescope (CFHT), SkyProbe is a system that allows the direct measurement of the true attenuation by clouds. This measurement is performed approximately once per min, directly on the field viewed by the telescope. It has been possible to make this system relatively inexpensively due to low cost CCD cameras available on the amateur market. A crucial addition to this hardware is the recent availability of a full-sky photometry catalog at the appropriate depth: the Tycho catalog from the Hipparcos mission. A very important element in the SkyProbe data set creation is the automatic data analysis pipeline, Elixir, developed at CFHT for the improved operation of the CFHT wide-field imagers CFH12K and MegaCam. SkyProbe's FITS images are processed in real time, and the pipeline output (a zero point attenuation) provides the current sky transmission to the observers and aids immediate decision making. These measurements are also attached to the archived data, adding a key tool for future use by other astronomers. Specific features of the detector, such as intra pixel quantum efficiency variations, must be taken into consideration since the data are strongly undersampled.

Future Sky Surveys: New Discovery Frontiers

NASA Astrophysics Data System (ADS)

Tyson, J. Anthony; Borne, Kirk D.

2012-03-01

Driven by the availability of new instrumentation, there has been an evolution in astronomical science toward comprehensive investigations of new phenomena. Major advances in our understanding of the Universe over the history of astronomy have often arisen from dramatic improvements in our capability to observe the sky to greater depth, in previously unexplored wavebands, with higher precision, or with improved spatial, spectral, or temporal resolution. Substantial progress in the important scientific problems of the next decade (determining the nature of dark energy and dark matter, studying the evolution of galaxies and the structure of our own Milky Way, opening up the time domain to discover faint variable objects, and mapping both the inner and outer Solar System) can be achieved through the application of advanced data mining methods and machine learning algorithms operating on the numerous large astronomical databases that will be generated from a variety of revolutionary future sky surveys. Over the next decade, astronomy will irrevocably enter the era of big surveys and of really big telescopes. New sky surveys (some of which will produce petabyte-scale data collections) will begin their operations, and one or more very large telescopes (ELTs = Extremely Large Telescopes) will enter the construction phase. These programs and facilities will generate a remarkable wealth of data of high complexity, endowed with enormous scientific knowledge discovery potential. New parameter spaces will be opened, in multiple wavelength domains as well as the time domain, across wide areas of the sky, and down to unprecedented faint source flux limits. The synergies of grand facilities, massive data collections, and advanced machine learning algorithms will come together to enable discoveries within most areas of astronomical science, including Solar System, exo-planets, star formation, stellar populations, stellar death, galaxy assembly, galaxy evolution, quasar evolution

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.

Verification of the ISO calibration method for field pyranometers under tropical sky conditions

NASA Astrophysics Data System (ADS)

Janjai, Serm; Tohsing, Korntip; Pattarapanitchai, Somjet; Detkhon, Pasakorn

2017-02-01

Field pyranomters need to be annually calibrated and the International Organization for Standardization (ISO) has defined a standard method (ISO 9847) for calibrating these pyranometers. According to this standard method for outdoor calibration, the field pyranometers have to be compared to a reference pyranometer for the period of 2 to 14 days, depending on sky conditions. In this work, the ISO 9847 standard method was verified under tropical sky conditions. To verify the standard method, calibration of field pyranometers was conducted at a tropical site located in Nakhon Pathom (13.82o N, 100.04o E), Thailand under various sky conditions. The conditions of the sky were monitored by using a sky camera. The calibration results for different time periods used for the calibration under various sky conditions were analyzed. It was found that the calibration periods given by this standard method could be reduced without significant change in the final calibration result. In addition, recommendation and discussion on the use of this standard method in the tropics were also presented.

SETI prototype system for NASA's Sky Survey microwave observing project - A progress report

NASA Technical Reports Server (NTRS)

Klein, M. J.; Gulkis, S.; Wilck, H. C.

1990-01-01

Two complementary search strategies, a Targeted Search and a Sky Survey, are part of NASA's SETI microwave observing project scheduled to begin in October of 1992. The current progress in the development of hardware and software elements of the JPL Sky Survey data processing system are presented. While the Targeted Search stresses sensitivity allowing the detection of either continuous or pulsed signals over the 1-3 GHz frequency range, the Sky Survey gives up sensitivity to survey the 99 percent of the sky that is not covered by the Targeted Search. The Sky Survey spans a larger frequency range from 1-10 GHz. The two searches will deploy special-purpose digital signal processing equipment designed and built to automate the observing and data processing activities. A two-million channel digital wideband spectrum analyzer and a signal processor system will serve as a prototype for the SETI Sky Survey processor. The design will permit future expansion to meet the SETI requirement that the processor concurrently search for left and right circularly polarized signals.

Two Methods for Retrieving UV Index for All Cloud Conditions from Sky Imager Products or Total SW Radiation Measurements

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

Badosa, Jordi; Calbo, J.; McKenzie, R. L.

2014-07-01

In the present study, we assess the cloud effects on UV Index (UVI) and total solar radiation (TR) as a function of cloud cover estimations and sunny conditions (from sky imaging products) as well as of solar zenith angle (SZA). These analyses are undertaken for a southern-hemisphere mid-latitude site where a 10-years dataset is available. It is confirmed that clouds reduce TR more than UV, in particular for obscured Sun conditions, low cloud fraction (< 60%) and large SZA (> 60º). Similarly, clouds enhance TR more than UV, mainly for visible Sun conditions, large cloud fraction and large SZA. Twomore » methods to estimate UVI are developed: 1) from sky imaging cloud cover and sunny conditions, and 2) from TR measurements. Both methods may be used in practical operational applications, although Method 2 shows overall the best performance, since TR allows accounting for cloud optical properties. The mean absolute differences of Method 2 estimations with respect to measured values are 0.17 UVI units (for 1-minute data) and 0.79 Standard Erythemal Dose (SED) units (for daily integrations). Method 1 shows less accurate results but it is still suitable to estimate UVI: mean absolute differences are 0.37 UVI units and 1.6 SED.« less

Fireballs in the Sky: an Augmented Reality Citizen Science Program

NASA Astrophysics Data System (ADS)

Day, B. H.; Bland, P.; Sayers, R.

2017-12-01

Fireballs in the Sky is an innovative Australian citizen science program that connects the public with the research of the Desert Fireball Network (DFN). This research aims to understand the early workings of the solar system, and Fireballs in the Sky invites people around the world to learn about this science, contributing fireball sightings via a user-friendly augmented reality mobile app. Tens of thousands of people have downloaded the app world-wide and participated in the science of meteoritics. The Fireballs in the Sky app allows users to get involved with the Desert Fireball Network research, supplementing DFN observations and providing enhanced coverage by reporting their own meteor sightings to DFN scientists. Fireballs in the Sky reports are used to track the trajectories of meteors - from their orbit in space to where they might have landed on Earth. Led by Phil Bland at Curtin University in Australia, the Desert Fireball Network (DFN) uses automated observatories across Australia to triangulate trajectories of meteorites entering the atmosphere, determine pre-entry orbits, and pinpoint their fall positions. Each observatory is an autonomous intelligent imaging system, taking 1000×36Megapixel all-sky images throughout the night, using neural network algorithms to recognize events. They are capable of operating for 12 months in a harsh environment, and store all imagery collected. We developed a completely automated software pipeline for data reduction, and built a supercomputer database for storage, allowing us to process our entire archive. The DFN currently stands at 50 stations distributed across the Australian continent, covering an area of 2.5 million km^2. Working with DFN's partners at NASA's Solar System Exploration Research Virtual Institute, the team is expanding the network beyond Australia to locations around the world. Fireballs in the Sky allows a growing public base to learn about and participate in this exciting research.

Predicting Clear-Sky Reflectance Over Snow/Ice in Polar Regions

NASA Technical Reports Server (NTRS)

Chen, Yan; Sun-Mack, Sunny; Arduini, Robert F.; Hong, Gang; Minnis, Patrick

2015-01-01

Satellite remote sensing of clouds requires an accurate estimate of the clear-sky radiances for a given scene to detect clouds and aerosols and to retrieve their microphysical properties. Knowing the spatial and angular variability of clear-sky albedo is essential for predicting clear-sky radiance at solar wavelengths. The Clouds and the Earth's Radiant Energy System (CERES) Project uses the nearinfrared (NIR; 1.24, 1.6 or 2.13 micrometers), visible (VIS; 0.63 micrometers) and vegetation (VEG; 0.86 micrometers) channels available on the Terra and Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) to help identify clouds and retrieve their properties in both snow-free and snow-covered conditions. Thus, it is critical to have reliable distributions of clear-sky albedo for all of these channels. In CERES Edition 4 (Ed4), the 1.24-micrometer channel is used to retrieve cloud optical depth over snow/ice-covered surfaces. Thus, it is especially critical to accurately predict the 1.24-micrometer clear-sky albedo alpha and reflectance rho for a given location and time. Snow albedo and reflectance patterns are very complex due to surface texture, particle shapes and sizes, melt water, and vegetation protrusions from the snow surface. To minimize those effects, this study focuses on the permanent snow cover of Antarctica where vegetation is absent and melt water is minimal. Clear-sky albedos are determined as a function of solar zenith angle (SZA) from observations over all scenes determined to be cloud-free to produce a normalized directional albedo model (DRM). The DRM is used to develop alpha(SZA=0 degrees) on 10 foot grid for each season. These values provide the basis for predicting r at any location and set of viewing & illumination conditions. This paper examines the accuracy of this approach for two theoretical snow surface reflectance models.

Fireballs in the Sky: An Augmented Reality Citizen Science Program

NASA Technical Reports Server (NTRS)

Day, Brian

2017-01-01

Fireballs in the Sky is an innovative Australian citizen science program that connects the public with the research of the Desert Fireball Network (DFN). This research aims to understand the early workings of the solar system, and Fireballs in the Sky invites people around the world to learn about this science, contributing fireball sightings via a user-friendly augmented reality mobile app. Tens of thousands of people have downloaded the app world-wide and participated in the science of meteoritics. The Fireballs in the Sky app allows users to get involved with the Desert Fireball Network research, supplementing DFN observations and providing enhanced coverage by reporting their own meteor sightings to DFN scientists. Fireballs in the Sky reports are used to track the trajectories of meteors - from their orbit in space to where they might have landed on Earth. Led by Phil Bland at Curtin University in Australia, the Desert Fireball Network (DFN) uses automated observatories across Australia to triangulate trajectories of meteorites entering the atmosphere, determine pre-entry orbits, and pinpoint their fall positions. Each observatory is an autonomous intelligent imaging system, taking 1000 by 36 megapixel all-sky images throughout the night, using neural network algorithms to recognize events. They are capable of operating for 12 months in a harsh environment, and store all imagery collected. We developed a completely automated software pipeline for data reduction, and built a supercomputer database for storage, allowing us to process our entire archive. The DFN currently stands at 50 stations distributed across the Australian continent, covering an area of 2.5 million square kilometers. Working with DFN's partners at NASA's Solar System Exploration Research Virtual Institute, the team is expanding the network beyond Australia to locations around the world. Fireballs in the Sky allows a growing public base to learn about and participate in this exciting research.

ROTSE All-Sky Surveys for Variable Stars. I. Test Fields

NASA Astrophysics Data System (ADS)

Akerlof, C.; Amrose, S.; Balsano, R.; Bloch, J.; Casperson, D.; Fletcher, S.; Gisler, G.; Hills, J.; Kehoe, R.; Lee, B.; Marshall, S.; McKay, T.; Pawl, A.; Schaefer, J.; Szymanski, J.; Wren, J.

2000-04-01

The Robotic Optical Transient Search Experiment I (ROTSE-I) experiment has generated CCD photometry for the entire northern sky in two epochs nightly since 1998 March. These sky patrol data are a powerful resource for studies of astrophysical transients. As a demonstration project, we present first results of a search for periodic variable stars derived from ROTSE-I observations. Variable identification, period determination, and type classification are conducted via automatic algorithms. In a set of nine ROTSE-I sky patrol fields covering roughly 2000 deg2, we identify 1781 periodic variable stars with mean magnitudes between mv=10.0 and mv=15.5. About 90% of these objects are newly identified as variable. Examples of many familiar types are presented. All classifications for this study have been manually confirmed. The selection criteria for this analysis have been conservatively defined and are known to be biased against some variable classes. This preliminary study includes only 5.6% of the total ROTSE-I sky coverage, suggesting that the full ROTSE-I variable catalog will include more than 32,000 periodic variable stars.

Status of the NASA SETI Sky Survey microwave observing project.

PubMed

Klein, M J; Gulkis, S; Wilck, H C; Olsen, E T; Garyantes, M F; Burns, D J; Asmar, P R; Brady, R B; Deich, W T; Renzetti, N A

1992-01-01

The Sky Survey observing program is one of two complementary strategies that NASA plans to use in its microwave Search for Extraterrestrial Intelligence (SETI). The primary objective of the Sky Survey is to search the entire sky over the frequency range 1000-10,000 MHz for evidence of narrow band signals of extraterrestrial, intelligent origin. Spectrum analyzers with upwards of 10 million channels and data rates in excess of 10 gigabits per second are required to complete the survey in less than 7 years. To lay the foundation for the operational SETI Sky Survey, a prototype system has been built to test and refine real time signal detection algorithms, to test scan strategies and observatory control functions, and to test algorithms designed to reject radio frequency interference. This paper presents a high level description of the prototype hardware and software and reports on the preparations to deploy the system to the 34-m antenna at the research and development station of NASA's Deep Space Communication Complex, Goldstone, California.

Full-Sky Maps of the VHF Radio Sky with the Owens Valley Radio Observatory Long Wavelength Array

NASA Astrophysics Data System (ADS)

Eastwood, Michael W.; Hallinan, Gregg

2018-05-01

21-cm cosmology is a powerful new probe of the intergalactic medium at redshifts 20 >~ z >~ 6 corresponding to the Cosmic Dawn and Epoch of Reionization. Current observations of the highly-redshifted 21-cm transition are limited by the dynamic range they can achieve against foreground sources of low-frequency (<200 MHz) of radio emission. We used the Owens Valley Radio Observatory Long Wavelength Array (OVRO-LWA) to generate a series of new modern high-fidelity sky maps that capture emission on angular scales ranging from tens of degrees to ~15 arcmin, and frequencies between 36 and 73 MHz. These sky maps were generated from the application of Tikhonov-regularized m-mode analysis imaging, which is a new interferometric imaging technique that is uniquely suited for low-frequency, wide-field, drift-scanning interferometers.

The "All Sky Camera Network"

ERIC Educational Resources Information Center

Caldwell, Andy

2005-01-01

In 2001, the "All Sky Camera Network" came to life as an outreach program to connect the Denver Museum of Nature and Science (DMNS) exhibit "Space Odyssey" with Colorado schools. The network is comprised of cameras placed strategically at schools throughout Colorado to capture fireballs--rare events that produce meteorites.…

Calculating clear-sky radiative heating rates using the Fu-Liou RTM with inputs from observed and reanalyzed profiles

NASA Astrophysics Data System (ADS)

Dolinar, E. K.; Dong, X.; Xi, B.

2015-12-01

One-dimensional radiative transfer models (RTM) are a common tool used for calculating atmospheric heating rates and radiative fluxes. In the forward sense, RTMs use known (or observed) quantities of the atmospheric state and surface characteristics to determine the appropriate surface and top-of-atmosphere (TOA) radiative fluxes. The NASA CERES science team uses the modified Fu-Liou RTM to calculate atmospheric heating rates and surface and TOA fluxes using the CERES observed TOA shortwave (SW) and longwave (LW) fluxes as constraints to derive global surface and TOA radiation budgets using a reanalyzed atmospheric state (e.g. temperature and various greenhouse gases) from the newly developed MERRA-2. However, closure studies have shown that using the reanalyzed state as input to the RTM introduces some disparity between the RTM calculated fluxes and surface observed ones. The purpose of this study is to generate a database of observed atmospheric state profiles, from satellite and ground-based sources, at several permanent Atmospheric Radiation Measurement (ARM) Program sites, including the Southern Great Plains (SGP), Northern Slope of Alaska (NSA) and Tropical Western Pacific Nauru (TWP-C2), and Eastern North Atlantic (ENA) permanent facilities. Since clouds are a major modulator of radiative transfer within the Earth's atmosphere, we will focus on the clear-sky conditions in this study, which will set up the baseline for our cloudy studies in the future. Clear-sky flux profiles are calculated using the Edition 4 NASA LaRC modified Fu-Liou RTM. The aforementioned atmospheric profiles generated in-house are used as input into the RTM, as well as from reanalyses. The calculated surface and TOA fluxes are compared with ARM surface measured and CERES satellite observed SW and LW fluxes, respectively. Clear-sky cases are identified by the ARM radar-lidar observations, as well as satellite observations, at the select ARM sites.

Radiative sky cooling: fundamental physics, materials, structures, and applications

DOE PAGES

Sun, Xingshu; Sun, Yubo; Zhou, Zhiguang; ...

2017-07-29

Radiative sky cooling reduces the temperature of a system by promoting heat exchange with the sky; its key advantage is that no input energy is required. We will review the origins of radiative sky cooling from ancient times to the modern day, and illustrate how the fundamental physics of radiative cooling calls for a combination of properties that may not occur in bulk materials. A detailed comparison with recent modeling and experiments on nanophotonic structures will then illustrate the advantages of this recently emerging approach. Potential applications of these radiative cooling materials to a variety of temperature-sensitive optoelectronic devices, suchmore » as photovoltaics, thermophotovoltaics, rectennas, and infrared detectors, will then be discussed. This review will conclude by forecasting the prospects for the field as a whole in both terrestrial and space-based systems.« less

AmeriFlux US-SO2 Sky Oaks- Old Stand

DOE Data Explorer

Oechel, Walt [San Diego State University

2016-01-01

This is the AmeriFlux version of the carbon flux data for the site US-SO2 Sky Oaks- Old Stand. Site Description - The Sky Oaks Old site is located near the Sky Oaks Field station, owned and operated by San Diego State University. Chaparral vegetation, associated with a Mediterranean climate, covers nearly half of the rough and rocky terrain. Precipitation is almost exclusively confined to the winter months. During the summer and early fall, hot and dry Santa Ana winds from the northeast bring desert heat to the site. A high intensity natural wildfire occurred in July of 2003. The stand age at the time of the wildfire was 80 years old, following an early wildfire poorly characterized. Following the 2003 wildfire, most native chaparral began to regrow from root stocks reaching a height of 1.0 m in 2008.

Radiative sky cooling: fundamental physics, materials, structures, and applications

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

Sun, Xingshu; Sun, Yubo; Zhou, Zhiguang

Radiative sky cooling reduces the temperature of a system by promoting heat exchange with the sky; its key advantage is that no input energy is required. We will review the origins of radiative sky cooling from ancient times to the modern day, and illustrate how the fundamental physics of radiative cooling calls for a combination of properties that may not occur in bulk materials. A detailed comparison with recent modeling and experiments on nanophotonic structures will then illustrate the advantages of this recently emerging approach. Potential applications of these radiative cooling materials to a variety of temperature-sensitive optoelectronic devices, suchmore » as photovoltaics, thermophotovoltaics, rectennas, and infrared detectors, will then be discussed. This review will conclude by forecasting the prospects for the field as a whole in both terrestrial and space-based systems.« less

Applying machine learning classification techniques to automate sky object cataloguing

NASA Astrophysics Data System (ADS)

Fayyad, Usama M.; Doyle, Richard J.; Weir, W. Nick; Djorgovski, Stanislav

1993-08-01

We describe the application of an Artificial Intelligence machine learning techniques to the development of an automated tool for the reduction of a large scientific data set. The 2nd Mt. Palomar Northern Sky Survey is nearly completed. This survey provides comprehensive coverage of the northern celestial hemisphere in the form of photographic plates. The plates are being transformed into digitized images whose quality will probably not be surpassed in the next ten to twenty years. The images are expected to contain on the order of 107 galaxies and 108 stars. Astronomers wish to determine which of these sky objects belong to various classes of galaxies and stars. Unfortunately, the size of this data set precludes analysis in an exclusively manual fashion. Our approach is to develop a software system which integrates the functions of independently developed techniques for image processing and data classification. Digitized sky images are passed through image processing routines to identify sky objects and to extract a set of features for each object. These routines are used to help select a useful set of attributes for classifying sky objects. Then GID3 (Generalized ID3) and O-B Tree, two inductive learning techniques, learns classification decision trees from examples. These classifiers will then be applied to new data. These developmnent process is highly interactive, with astronomer input playing a vital role. Astronomers refine the feature set used to construct sky object descriptions, and evaluate the performance of the automated classification technique on new data. This paper gives an overview of the machine learning techniques with an emphasis on their general applicability, describes the details of our specific application, and reports the initial encouraging results. The results indicate that our machine learning approach is well-suited to the problem. The primary benefit of the approach is increased data reduction throughput. Another benefit is

Water Detection Based on Sky Reflections

NASA Technical Reports Server (NTRS)

Rankin, Arturo L.; Matthies, Larry H.

2010-01-01

This software has been designed to detect water bodies that are out in the open on cross-country terrain at mid- to far-range (approximately 20 100 meters), using imagery acquired from a stereo pair of color cameras mounted on a terrestrial, unmanned ground vehicle (UGV). Non-traversable water bodies, such as large puddles, ponds, and lakes, are indirectly detected by detecting reflections of the sky below the horizon in color imagery. The appearance of water bodies in color imagery largely depends on the ratio of light reflected off the water surface to the light coming out of the water body. When a water body is far away, the angle of incidence is large, and the light reflected off the water surface dominates. We have exploited this behavior to detect water bodies out in the open at mid- to far-range. When a water body is detected at far range, a UGV s path planner can begin to look for alternate routes to the goal position sooner, rather than later. As a result, detecting water hazards at far range generally reduces the time required to reach a goal position during autonomous navigation. This software implements a new water detector based on sky reflections that geometrically locates the exact pixel in the sky that is reflecting on a candidate water pixel on the ground, and predicts if the ground pixel is water based on color similarity and local terrain features

Sky Observations by the Book

ERIC Educational Resources Information Center

Trundle, Kathy Cabe; Sackes, Mesut

2008-01-01

The "National Science Education Standards (NSES)" state that students in grades K-4 are expected to understand that astronomical objects in the sky, including the Sun, Moon, and stars--have properties, locations, and patterns of movement that can be observed and described. They further suggest using an inquiry-based approach to teach…

Teachable Fiction Comes to Yellow Sky.

ERIC Educational Resources Information Center

Tietz, Stephen

2001-01-01

Proposes that teachable fiction is efficient, strategically sound, and very visual. Analyzes Stephen Crane's "The Bride Comes to Yellow Sky" to show it fulfills these three characteristics. Suggests the story should be taught later in the semester. (PM)

The Automatic Recognition of the Abnormal Sky-subtraction Spectra Based on Hadoop

NASA Astrophysics Data System (ADS)

An, An; Pan, Jingchang

2017-10-01

The skylines, superimposing on the target spectrum as a main noise, If the spectrum still contains a large number of high strength skylight residuals after sky-subtraction processing, it will not be conducive to the follow-up analysis of the target spectrum. At the same time, the LAMOST can observe a quantity of spectroscopic data in every night. We need an efficient platform to proceed the recognition of the larger numbers of abnormal sky-subtraction spectra quickly. Hadoop, as a distributed parallel data computing platform, can deal with large amounts of data effectively. In this paper, we conduct the continuum normalization firstly and then a simple and effective method will be presented to automatic recognize the abnormal sky-subtraction spectra based on Hadoop platform. Obtain through the experiment, the Hadoop platform can implement the recognition with more speed and efficiency, and the simple method can recognize the abnormal sky-subtraction spectra and find the abnormal skyline positions of different residual strength effectively, can be applied to the automatic detection of abnormal sky-subtraction of large number of spectra.

Spinning projectile's attitude measurement with LW infrared radiation under sea-sky background

NASA Astrophysics Data System (ADS)

Xu, Miaomiao; Bu, Xiongzhu; Yu, Jing; He, Zilu

2018-05-01

With the further development of infrared radiation research in sea-sky background and the requirement of spinning projectile's attitude measurement, the sea-sky infrared radiation field is used to carry out spinning projectile's attitude angle instead of inertial sensors. Firstly, the generation mechanism of sea-sky infrared radiation is analysed. The mathematical model of sea-sky infrared radiation is deduced in LW (long wave) infrared 8 ∼ 14 μm band by calculating the sea surface and sky infrared radiation. Secondly, according to the movement characteristics of spinning projectile, the attitude measurement model of infrared sensors on projectile's three axis is established. And the feasibility of the model is analysed by simulation. Finally, the projectile's attitude calculation algorithm is designed to improve the attitude angle estimation accuracy. The results of semi-physical experiments show that the segmented interactive algorithm estimation error of pitch and roll angle is within ±1.5°. The attitude measurement method is effective and feasible, and provides accurate measurement basis for the guidance of spinning projectile.

A Strategy for Urban Astronomical Observatory Site Preservation: The Southern Arizona Example (Abstract)

NASA Astrophysics Data System (ADS)

Craine, E. R.; Craine, B. L.; Craine, P. R.; Craine, E. M.; Fouts, S.

2014-12-01

(Abstract only) Urbanized observatories are under financial pressures for numerous and complex reasons, including concerns that increasing sky brightness will continue to erode their scientific viability. The history of urbanized observatories is one of steady decline and divestiture. We argue that light at night (LAN) impacts of urban growth are inadequately understood, that current measurement techniques are incomplete in scope, and that both limit the effectiveness of mitigation programs. We give examples of these factors for Pima County, Arizona, and propose techniques and a program that could provide focus and power to mitigation efforts, and could extend the longevity of southern Arizona observatories.

Integration of polarization and chromatic cues in the insect sky compass.

PubMed

el Jundi, Basil; Pfeiffer, Keram; Heinze, Stanley; Homberg, Uwe

2014-06-01

Animals relying on a celestial compass for spatial orientation may use the position of the sun, the chromatic or intensity gradient of the sky, the polarization pattern of the sky, or a combination of these cues as compass signals. Behavioral experiments in bees and ants, indeed, showed that direct sunlight and sky polarization play a role in sky compass orientation, but the relative importance of these cues are species-specific. Intracellular recordings from polarization-sensitive interneurons in the desert locust and monarch butterfly suggest that inputs from different eye regions, including polarized-light input through the dorsal rim area of the eye and chromatic/intensity gradient input from the main eye, are combined at the level of the medulla to create a robust compass signal. Conflicting input from the polarization and chromatic/intensity channel, resulting from eccentric receptive fields, is eliminated at the level of the anterior optic tubercle and central complex through internal compensation for changing solar elevations, which requires input from a circadian clock. Across several species, the central complex likely serves as an internal sky compass, combining E-vector information with other celestial cues. Descending neurons, likewise, respond both to zenithal polarization and to unpolarized cues in an azimuth-dependent way.

Variable gamma-ray sky at 1 GeV

NASA Astrophysics Data System (ADS)

Pshirkov, M. S.; Rubtsov, G. I.

2013-01-01

We search for the long-term variability of the gamma-ray sky in the energy range E > 1 GeV with 168 weeks of the gamma-ray telescope Fermi-LAT data. We perform a full sky blind search for regions with variable flux looking for deviations from uniformity. We bin the sky into 12288 pixels using the HEALPix package and use the Kolmogorov-Smirnov test to compare weekly photon counts in each pixel with the constant flux hypothesis. The weekly exposure of Fermi-LAT for each pixel is calculated with the Fermi-LAT tools. We consider flux variations in a pixel significant if the statistical probability of uniformity is less than 4 × 10-6, which corresponds to 0.05 false detections in the whole set. We identified 117 variable sources, 27 of which have not been reported variable before. The sources with previously unidentified variability contain 25 active galactic nuclei (AGN) belonging to the blazar class (11 BL Lacs and 14 FSRQs), one AGN of an uncertain type, and one pulsar PSR J0633+1746 (Geminga).

Exposed Bedrock in the Koval'sky Impact Basin

NASA Image and Video Library

2017-06-27

This image shows partially exposed bedrock within the Koval'sky impact basin, which is on the outskirts of the extensive lava field of Daedalia Planum. Daedalia Planum is located southwest of Arsia Mons, which may be the source responsible for filling the crater with lava flows and ash deposits. On one side, bright bedrock with scattered dark blue spots are seen. The dark blue spots are boulders shedding from the outcrops. The color range of the bedrock provides some information on its composition. The blue color is indicative of the presence of iron-rich minerals that are generally not oxidized (i.e., rusted), unlike most of the ruddy Martian surface. Volcanic rocks are common on Mars. Possible candidate minerals for the bluish materials are often consistent with iron-rich minerals, such as pyroxene and olivine. The ridges may represent remnants of the original surface of the lava flows that filled the Koval'sky impact basin. NB: The region is named for M. A. Koval'sky, a Russian astronomer. https://photojournal.jpl.nasa.gov/catalog/PIA21765

SkyQuery - A Prototype Distributed Query and Cross-Matching Web Service for the Virtual Observatory

NASA Astrophysics Data System (ADS)

Thakar, A. R.; Budavari, T.; Malik, T.; Szalay, A. S.; Fekete, G.; Nieto-Santisteban, M.; Haridas, V.; Gray, J.

2002-12-01

We have developed a prototype distributed query and cross-matching service for the VO community, called SkyQuery, which is implemented with hierarchichal Web Services. SkyQuery enables astronomers to run combined queries on existing distributed heterogeneous astronomy archives. SkyQuery provides a simple, user-friendly interface to run distributed queries over the federation of registered astronomical archives in the VO. The SkyQuery client connects to the portal Web Service, which farms the query out to the individual archives, which are also Web Services called SkyNodes. The cross-matching algorithm is run recursively on each SkyNode. Each archive is a relational DBMS with a HTM index for fast spatial lookups. The results of the distributed query are returned as an XML DataSet that is automatically rendered by the client. SkyQuery also returns the image cutout corresponding to the query result. SkyQuery finds not only matches between the various catalogs, but also dropouts - objects that exist in some of the catalogs but not in others. This is often as important as finding matches. We demonstrate the utility of SkyQuery with a brown-dwarf search between SDSS and 2MASS, and a search for radio-quiet quasars in SDSS, 2MASS and FIRST. The importance of a service like SkyQuery for the worldwide astronomical community cannot be overstated: data on the same objects in various archives is mapped in different wavelength ranges and looks very different due to different errors, instrument sensitivities and other peculiarities of each archive. Our cross-matching algorithm preforms a fuzzy spatial join across multiple catalogs. This type of cross-matching is currently often done by eye, one object at a time. A static cross-identification table for a set of archives would become obsolete by the time it was built - the exponential growth of astronomical data means that a dynamic cross-identification mechanism like SkyQuery is the only viable option. SkyQuery was funded by a

Sky camera geometric calibration using solar observations

DOE PAGES

Urquhart, Bryan; Kurtz, Ben; Kleissl, Jan

2016-09-05

A camera model and associated automated calibration procedure for stationary daytime sky imaging cameras is presented. The specific modeling and calibration needs are motivated by remotely deployed cameras used to forecast solar power production where cameras point skyward and use 180° fisheye lenses. Sun position in the sky and on the image plane provides a simple and automated approach to calibration; special equipment or calibration patterns are not required. Sun position in the sky is modeled using a solar position algorithm (requiring latitude, longitude, altitude and time as inputs). Sun position on the image plane is detected using a simple image processing algorithm. Themore » performance evaluation focuses on the calibration of a camera employing a fisheye lens with an equisolid angle projection, but the camera model is general enough to treat most fixed focal length, central, dioptric camera systems with a photo objective lens. Calibration errors scale with the noise level of the sun position measurement in the image plane, but the calibration is robust across a large range of noise in the sun position. In conclusion, calibration performance on clear days ranged from 0.94 to 1.24 pixels root mean square error.« less

The Other Dark Sky

NASA Astrophysics Data System (ADS)

Pazmino, John

In previous demonstrations of New York's elimination of luminous graffiti from its skies, I focused attention on large-scale projects in the showcase districts of Manhattan. Although these works earned passionate respect in the dark sky movement, they by the same token were disheartening. New York was in some quarters of the movement regarded more as an unachievable Shangri-La than as a role model to emulate. This presentation focuses on scenes of light abatement efforts in parts of New York which resemble other towns in scale and density. I photographed these scenes along a certain bus route in Brooklyn on my way home from work during October 2001. This route circulates through various "bedroom communities," each similar to a mid-size to large town elsewhere in the United States. The sujbects included individual structures - stores, banks, schools - and streetscapes mimicking downtowns. The latter protrayed a mix of atrocious and excellent lighting practice, being that these streets are in transition by the routine process of replacement and renovation. The fixtures used - box lamps, fluted or Fresnel globes, subdued headsigns, indirect lighting - are casually obtainable by property managers at local outlets for lighting apparatus. They are routinely offered to the property managers by storefront designers, security services, contractors, and the community improvement or betterment councils.

Sky brightness and color measurements during the 21 August 2017 total solar eclipse.

PubMed

Bruns, Donald G; Bruns, Ronald D

2018-06-01

The sky brightness was measured during the partial phases and during totality of the 21 August 2017 total solar eclipse. A tracking CCD camera with color filters and a wide-angle lens allowed measurements across a wide field of view, recording images every 10 s. The partially and totally eclipsed Sun was kept behind an occulting disk attached to the camera, allowing direct brightness measurements from 1.5° to 38° from the Sun. During the partial phases, the sky brightness as a function of time closely followed the integrated intensity of the unobscured fraction of the solar disk. A redder sky was measured close to the Sun just before totality, caused by the redder color of the exposed solar limb. During totality, a bluer sky was measured, dimmer than the normal sky by a factor of 10,000. Suggestions for enhanced measurements at future eclipses are offered.

Integrating paleoecology and genetics of bird populations in two sky island archipelagos

PubMed Central

McCormack, John E; Bowen, Bonnie S; Smith, Thomas B

2008-01-01

Background Genetic tests of paleoecological hypotheses have been rare, partly because recent genetic divergence is difficult to detect and time. According to fossil plant data, continuous woodland in the southwestern USA and northern Mexico became fragmented during the last 10,000 years, as warming caused cool-adapted species to retreat to high elevations. Most genetic studies of resulting 'sky islands' have either failed to detect recent divergence or have found discordant evidence for ancient divergence. We test this paleoecological hypothesis for the region with intraspecific mitochondrial DNA and microsatellite data from sky-island populations of a sedentary bird, the Mexican jay (Aphelocoma ultramarina). We predicted that populations on different sky islands would share common, ancestral alleles that existed during the last glaciation, but that populations on each sky island, owing to their isolation, would contain unique variants of postglacial origin. We also predicted that divergence times estimated from corrected genetic distance and a coalescence model would post-date the last glacial maximum. Results Our results provide multiple independent lines of support for postglacial divergence, with the predicted pattern of shared and unique mitochondrial DNA haplotypes appearing in two independent sky-island archipelagos, and most estimates of divergence time based on corrected genetic distance post-dating the last glacial maximum. Likewise, an isolation model based on multilocus gene coalescence indicated postglacial divergence of five pairs of sky islands. In contrast to their similar recent histories, the two archipelagos had dissimilar historical patterns in that sky islands in Arizona showed evidence for older divergence, suggesting different responses to the last glaciation. Conclusion This study is one of the first to provide explicit support from genetic data for a postglacial divergence scenario predicted by one of the best paleoecological records in the

Towards the intrahour forecasting of direct normal irradiance using sky-imaging data.

PubMed

Nou, Julien; Chauvin, Rémi; Eynard, Julien; Thil, Stéphane; Grieu, Stéphane

2018-04-01

Increasing power plant efficiency through improved operation is key in the development of Concentrating Solar Power (CSP) technologies. To this end, one of the most challenging topics remains accurately forecasting the solar resource at a short-term horizon. Indeed, in CSP plants, production is directly impacted by both the availability and variability of the solar resource and, more specifically, by Direct Normal Irradiance (DNI). The present paper deals with a new approach to the intrahour forecasting (the forecast horizon [Formula: see text] is up to [Formula: see text] ahead) of DNI, taking advantage of the fact that this quantity can be split into two terms, i.e. clear-sky DNI and the clear sky index. Clear-sky DNI is forecasted from DNI measurements, using an empirical model (Ineichen and Perez, 2002) combined with a persistence of atmospheric turbidity. Moreover, in the framework of the CSPIMP (Concentrating Solar Power plant efficiency IMProvement) research project, PROMES-CNRS has developed a sky imager able to provide High Dynamic Range (HDR) images. So, regarding the clear-sky index, it is forecasted from sky-imaging data, using an Adaptive Network-based Fuzzy Inference System (ANFIS). A hybrid algorithm that takes inspiration from the classification algorithm proposed by Ghonima et al. (2012) when clear-sky anisotropy is known and from the hybrid thresholding algorithm proposed by Li et al. (2011) in the opposite case has been developed to the detection of clouds. Performance is evaluated via a comparative study in which persistence models - either a persistence of DNI or a persistence of the clear-sky index - are included. Preliminary results highlight that the proposed approach has the potential to outperform these models (both persistence models achieve similar performance) in terms of forecasting accuracy: over the test data used, RMSE (the Root Mean Square Error) is reduced of about [Formula: see text], with [Formula: see text], and [Formula: see

Integrating paleoecology and genetics of bird populations in two sky island archipelagos.

PubMed

McCormack, John E; Bowen, Bonnie S; Smith, Thomas B

2008-06-27

Genetic tests of paleoecological hypotheses have been rare, partly because recent genetic divergence is difficult to detect and time. According to fossil plant data, continuous woodland in the southwestern USA and northern Mexico became fragmented during the last 10,000 years, as warming caused cool-adapted species to retreat to high elevations. Most genetic studies of resulting 'sky islands' have either failed to detect recent divergence or have found discordant evidence for ancient divergence. We test this paleoecological hypothesis for the region with intraspecific mitochondrial DNA and microsatellite data from sky-island populations of a sedentary bird, the Mexican jay (Aphelocoma ultramarina). We predicted that populations on different sky islands would share common, ancestral alleles that existed during the last glaciation, but that populations on each sky island, owing to their isolation, would contain unique variants of postglacial origin. We also predicted that divergence times estimated from corrected genetic distance and a coalescence model would post-date the last glacial maximum. Our results provide multiple independent lines of support for postglacial divergence, with the predicted pattern of shared and unique mitochondrial DNA haplotypes appearing in two independent sky-island archipelagos, and most estimates of divergence time based on corrected genetic distance post-dating the last glacial maximum. Likewise, an isolation model based on multilocus gene coalescence indicated postglacial divergence of five pairs of sky islands. In contrast to their similar recent histories, the two archipelagos had dissimilar historical patterns in that sky islands in Arizona showed evidence for older divergence, suggesting different responses to the last glaciation. This study is one of the first to provide explicit support from genetic data for a postglacial divergence scenario predicted by one of the best paleoecological records in the world. Our results

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

Development test results of the Portable, Reconfigurable Sky Sensor (PRSS)

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

Blattman, D.A.

1993-12-31

The protection of assets against surreptitious access from the sky is a continuing problem. The Portable, Reconfigurable Sky Sensor is designed to provide volumetric intruder detection against low-observable aircraft, helicopters, and parachutists in the sky. Multiple systems may be joined to form continuous detection volume for applications such as borders. The PRSS is resistant to nuisance alarms due to wind up to 70 mph, rain/snow up to 6 inches/hour or small targets such as birds. The PRSS has been successfully tested against multiple intrusions with altitude range from 50 to 3,000 feet and cross-range up to 3,000 feet. This papermore » summarizes some of these field tests and lists specifications and potential uses.« less

A comparison of Stokes parameters for sky and a soybean canopy

NASA Technical Reports Server (NTRS)

Schutt, John B.; Holben, Brent N.; Mcmurtrey, James E., III

1991-01-01

An evaluation of the polarization signatures obtained from the four Stokes parameters is reported for the atmosphere and a soybean canopy. The polarimeter design and operation are set forth, and the Stokes parameters' relationships are discussed. The canopy polarization was different from the sky at azimuths of 90 and 270 degrees, demonstrating a response that reflecting the sky polarization signatures across a plane parallel to the polarization axis and passing through a phase angle of about 90 degrees would produce. Classical behavior in terms of electromagnetic theory was found in the fourth Stokes parameter of the canopy which was obtained in the principal plane. Only the third Stokes parameter is demonstrated to be unambiguously affected in a comparison of sky polarization signatures and aerosol optical densities. The similarity between the sky at azimuth 180 degrees and the soybean canopy data at the principal plane is interesting considering the disparity of the subjects.

Big Sky and Greenhorn Drilling Area on Mount Sharp

NASA Image and Video Library

2015-12-17

This view from the Mast Camera (Mastcam) on NASA's Curiosity Mars rover covers an area in "Bridger Basin" that includes the locations where the rover drilled a target called "Big Sky" on the mission's Sol 1119 (Sept. 29, 2015) and a target called "Greenhorn" on Sol 1137 (Oct. 18, 2015). The scene combines portions of several observations taken from sols 1112 to 1126 (Sept. 22 to Oct. 6, 2015) while Curiosity was stationed at Big Sky drilling site. The Big Sky drill hole is visible in the lower part of the scene. The Greenhorn target, in a pale fracture zone near the center of the image, had not yet been drilled when the component images were taken. Researchers selected this pair of drilling sites to investigate the nature of silica enrichment in the fracture zones of the area. http://photojournal.jpl.nasa.gov/catalog/PIA20270

The BAA Campaign for Dark Skies: Fifteen years on

NASA Astrophysics Data System (ADS)

Mizon, R.

2004-06-01

The starry sky is, unofficially but indubitably, a site of special scientific interest and an area of outstanding natural beauty - if it can be seen. The BAA's Campaign for Dark Skies (CfDS) was set up by concerned members in 1989, to counter the ever-growing tide of skyglow which has tainted the night sky over Britain since the 1950s. Once caused almost exclusively by poorly aimed streetlamps and building floodlights emitting light above the horizontal, skyglow is nowadays increasingly the result of vastly over-powered, poorly mounted household security lights and literally 'over-the-top' sports lighting. CfDS has grown into a network of 124 volunteer local officers, and several hundred committed supporters, who aim to persuade their local councils and relevant organisations of the benefits of well directed lighting, the motto being: the right amount of light, and only where needed.

A Study on New Song of the Sky Pacers

NASA Astrophysics Data System (ADS)

Ahn, Sang-Hyeon

2009-12-01

We investigated `Song of the Sky Pacers, Adopted to the New Methods' (新法步天歌), the latest version of Joseon's `Song of the Sky Pacers' (步天歌). Due to the influence of new knowledge on Chinese asterisms imported from the Ching dynasty, `Song of the Sky Pacers with New Star-Charts' was written in the eighteenth century. However, the disagreement between song and star-charts was causing confusion in practical applications such as Joseon's national examination for selecting astronomers. In order to improve this situation, Royal Observatory of the Joseon dynasty (觀象監) published `Song of the Sky Pacers, Adopted to the New Methods' based upon star-charts and song in the Sequel of I-Hsiang-K'ao-ch'eng (欽定儀象考成續編). The New Song was edited by a middle-class professional astronomer Yi Jun-yang (李俊養), and corrected by a nobleman Nam Byeong-gil (南秉吉). We establish a brief biography of Yi Jun-yang. The New Song preserves the genuine characteristics of previous Joseon's Song including the format of title of each lunar mansion and description on the location of the Milky Way in the asterisms. The description of the Milky Way was newly written based on the data in volume 31 and 32 of the Sequel of I-Hsiang-K'ao-ch'eng.

a Study of Sasin-Animal Sky Map on Chonmunryucho

NASA Astrophysics Data System (ADS)

Yang, Hong-Jin; Park, Myeong-Gu

2003-03-01

Chon-Mun-Ryu-Cho, written (edited) by Lee Sun-Ji during the period of King Se-Jong, is a representative astronomy book of Cho-Sun (A.D. 1392 -1910) Dynasty. We find and study in the first page of the book; the description of 28 oriental constellations as a Sasin (four mythical oriental animals)-animal sky map which is not widely known yet. The map consists of four groups of constellations, each of which represents the Sasin: Chang-Ryong (dragon), Baek-Ho (tigers with Ki-Rin [Oriental giraffe]), Ju-Jak (Chinese phoenix), Hyun-Mu (a tortoise interwined with a snake). Each group (animals) spans 2˜7 of 28 oriental constellations As we know from the illustration of the Chon-Sang-Yol-Cha-Bun-Ya-Ji-Do a representative sky map of Cho-Sun Dynasty, astronomy in Cho-Sun Dynasty is closely related to that in Go-Gu-Ryer (B.C. 37 -A.D. 668) Dynasty. Since these Sasin-animals appear in most mural paintings of Go-Gu-Ryer tombs, visualization of sky with these animal constellations could have been established as early as in Go-Gu-Ryer Dynasty. We also reconstruct this ''A Sasin-animal Korean sky map'' based on the shapes of the Sasin and Ki-Rin from Go-Gu-Ryer paintings and 28 oriental constellations in Chon-Sang-Yol-Cha-Bun-Ya-Ji-Do.

The SPHEREx All-Sky Spectral Survey

NASA Astrophysics Data System (ADS)

Bock, James; SPHEREx Science Team

2018-01-01

SPHEREx, a mission in NASA's Medium Explorer (MIDEX) program that was selected for Phase A in August 2017, is an all-sky survey satellite designed to address all three science goals in NASA's astrophysics division, with a single instrument, a wide-field spectral imager. SPHEREx will probe the physics of inflation by measuring non-Gaussianity by studying large-scale structure, surveying a large cosmological volume at low redshifts, complementing high-z surveys optimized to constrain dark energy. The origin of water and biogenic molecules will be investigated in all phases of planetary system formation - from molecular clouds to young stellar systems with protoplanetary disks - by measuring ice absorption spectra. We will chart the origin and history of galaxy formation through a deep survey mapping large-scale spatial power in two deep fields located near the ecliptic poles. Following in the tradition of all-sky missions such as IRAS, COBE and WISE, SPHEREx will be the first all-sky near-infrared spectral survey. SPHEREx will create spectra (0.75 – 4.2 um at R = 41; and 4.2 – 5 um at R = 135) with high sensitivity making background-limited observations using a passively-cooled telescope with a wide field-of-view for large mapping speed. During its two-year mission, SPHEREx will produce four complete all-sky maps that will serve as a rich archive for the astronomy community. With over a billion detected galaxies, hundreds of millions of high-quality stellar and galactic spectra, and over a million ice absorption spectra, the archive will enable diverse scientific investigations including studies of young stellar systems, brown dwarfs, high-redshift quasars, galaxy clusters, the interstellar medium, asteroids and comets. All aspects of the instrument and spacecraft have high heritage. SPHEREx requires no new technologies and carries large technical and resource margins on every aspect of the design. SPHEREx is a partnership between Caltech and JPL, following the

Red Sky with Red Mesa

ScienceCinema

None

2018-01-16

The Red Sky/Red Mesa supercomputing platform dramatically reduces the time required to simulate complex fuel models, from 4-6 months to just 4 weeks, allowing researchers to accelerate the pace at which they can address these complex problems. Its speed also reduces the need for laboratory and field testing, allowing for energy reduction far beyond data center walls.

Receptive fields of locust brain neurons are matched to polarization patterns of the sky.

PubMed

Bech, Miklós; Homberg, Uwe; Pfeiffer, Keram

2014-09-22

Many animals, including insects, are able to use celestial cues as a reference for spatial orientation and long-distance navigation [1]. In addition to direct sunlight, the chromatic gradient of the sky and its polarization pattern are suited to serve as orientation cues [2-5]. Atmospheric scattering of sunlight causes a regular pattern of E vectors in the sky, which are arranged along concentric circles around the sun [5, 6]. Although certain insects rely predominantly on sky polarization for spatial orientation [7], it has been argued that detection of celestial E vector orientation may not suffice to differentiate between solar and antisolar directions [8, 9]. We show here that polarization-sensitive (POL) neurons in the brain of the desert locust Schistocerca gregaria can overcome this ambiguity. Extracellular recordings from POL units in the central complex and lateral accessory lobes revealed E vector tunings arranged in concentric circles within large receptive fields, matching the sky polarization pattern at certain solar positions. Modeling of neuronal responses under an idealized sky polarization pattern (Rayleigh sky) suggests that these "matched filter" properties allow locusts to unambiguously determine the solar azimuth by relying solely on the sky polarization pattern for compass navigation. Copyright © 2014 Elsevier Ltd. All rights reserved.

Losing Sleep to Watch the Night-Sky: The Relationship between Sleep-Length and Noctcaelador

ERIC Educational Resources Information Center

Kelly, William E.; Rose, Callie

2005-01-01

For most of history, humans have been watching the night-sky (Hawkins, 1983). Historically, individuals have watched the night-sky for aesthetic appreciation and to gain insights and knowledge (Brecher & Feirtag, 1979). Despite the long history of night-sky watching among humans and the apparent importance of the behavior to large groups of…

Analysis of the Best-Fit Sky Model Produced Through Redundant Calibration of Interferometers

NASA Astrophysics Data System (ADS)

Storer, Dara; Pober, Jonathan

2018-01-01

21 cm cosmology provides unique insights into the formation of stars and galaxies in the early universe, and particularly the Epoch of Reionization. Detection of the 21 cm line is challenging because it is generally 4-5 magnitudes weaker than the emission from foreground sources, and therefore the instruments used for detection must be carefully designed and calibrated. 21 cm cosmology is primarily conducted using interferometers, which are difficult to calibrate because of their complex structure. Here I explore the relationship between sky-based calibration, which relies on an accurate and comprehensive sky model, and redundancy-based calibration, which makes use of redundancies in the orientation of the interferometer's dishes. In addition to producing calibration parameters, redundant calibration also produces a best fit model of the sky. In this work I examine that sky model and explore the possibility of using that best fit model as an additional input to improve on sky-based calibration.

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.

Curiosity Sky Crane Maneuver, Artist Concept

NASA Image and Video Library

2011-10-03

This artist concept shows the sky crane maneuver during the descent of NASA Curiosity rover to the Martian surface. The sheer size of the rover over one ton, or 900 kilograms would preclude it from taking advantage of an airbag-assisted landing.

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.

THE MILKY WAY TOMOGRAPHY WITH SLOAN DIGITAL SKY SURVEY. IV. DISSECTING DUST

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

Berry, Michael; Ivezic, Zeljko; Brooks, Keira J.

2012-10-01

We use Sloan Digital Sky Survey (SDSS) photometry of 73 million stars to simultaneously constrain best-fit main-sequence stellar spectral energy distribution (SED) and amount of dust extinction along the line of sight toward each star. Using a subsample of 23 million stars with Two Micron All Sky Survey (2MASS) photometry, whose addition enables more robust results, we show that SDSS photometry alone is sufficient to break degeneracies between intrinsic stellar color and dust amount when the shape of extinction curve is fixed. When using both SDSS and 2MASS photometry, the ratio of the total to selective absorption, R{sub V} ,more » can be determined with an uncertainty of about 0.1 for most stars in high-extinction regions. These fits enable detailed studies of the dust properties and its spatial distribution, and of the stellar spatial distribution at low Galactic latitudes (|b| < 30 Degree-Sign ). Our results are in good agreement with the extinction normalization given by the Schlegel et al. (SFD) dust maps at high northern Galactic latitudes, but indicate that the SFD extinction map appears to be consistently overestimated by about 20% in the southern sky, in agreement with recent study by Schlafly et al. The constraints on the shape of the dust extinction curve across the SDSS and 2MASS bandpasses disfavor the reddening law of O'Donnell, but support the models by Fitzpatrick and Cardelli et al. For the latter, we find a ratio of the total to selective absorption to be R{sub V} = 3.0 {+-} 0.1(random){+-}0.1 (systematic) over most of the high-latitude sky. At low Galactic latitudes (|b| < 5 Degree-Sign ), we demonstrate that the SFD map cannot be reliably used to correct for extinction because most stars are embedded in dust, rather than behind it, as is the case at high Galactic latitudes. We analyze three-dimensional maps of the best-fit R{sub V} and find that R{sub V} = 3.1 cannot be ruled out in any of the 10 SEGUE stripes at a precision level of {approx

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".

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.

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.

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.

Starry Sky Pattern in Hematopoietic Neoplasms: A Review of Pathophysiology and Differential Diagnosis.

PubMed

Dy-Ledesma, Janelyn L; Khoury, Joseph D; Agbay, Rose Lou Marie C; Garcia, Mar; Miranda, Roberto N; Medeiros, L Jeffrey

2016-11-01

The starry sky pattern is a distinctive histologic feature wherein a rapidly proliferating hematolymphoid neoplasm contains scattered histiocytes with abundant pale cytoplasm in a background of monomorphic neoplastic cells. The cytoplasm of these histiocytes typically contains cellular remnants, also known as tingible bodies, incorporated through active phagocytosis. Although common and widely recognized, relatively little is known about the pathophysiological underpinnings of the starry sky pattern. Its resemblance to a similar pattern seen in the germinal centers of secondary follicles suggests a possible starting point for understanding the molecular basis of the starry sky pattern and potential routes for its exploitation for therapeutic purposes. In this review, we discuss the historical, pathophysiological, and clinical implications of the starry sky pattern.

Observing floods from space: Experience gained from COSMO-SkyMed observations

NASA Astrophysics Data System (ADS)

Pierdicca, N.; Pulvirenti, L.; Chini, M.; Guerriero, L.; Candela, L.

2013-03-01

The COSMO-SkyMed mission offers a unique opportunity to obtain all weather radar images characterized by short revisit time, thus being useful for flood evolution mapping. The COSMO-SkyMed system has been activated several times in the last few years in occasion of flood events all over the world in order to provide very high resolution X-band SAR images useful for flood detection purposes. This paper discusses the major outcomes of the experience gained, within the framework of the OPERA Pilot Project funded by the Italian Space Agency, from using COSMO-SkyMed data for the purpose of near real time generation of flood maps. A review of the mechanisms which determine the imprints of the inundation on the radar images and of the fundamental simulation tools able to predict these imprints and help image interpretation is provided. The approach developed to process the data and to generate the flood maps is also summarized. Then, the paper illustrates the experience gained with COSMO-SkyMed by describing and discussing a number of significant examples. These examples demonstrate the potential of the COSMO-SkyMed system and the suitability of the approach developed for generating the final products, but they also highlight some critical aspects that require further investigations to improve the reliability of the flood maps.

All-Sky Monitoring of Variable Sources with Fermi GBM

NASA Technical Reports Server (NTRS)

Wilson-Hodge, Colleen A.; Finger, Mark; Camero-Arranz, Ascension; Becklen, Elif; Jenke, Peter; Cpe. K/ K/; Steele, Iain; Case, Gary; Cherry, Mike; Rodi, James;

Impacts of field of view configuration of Cross-track Infrared Sounder on clear-sky observations.

PubMed

Wang, Likun; Chen, Yong; Han, Yong

2016-09-01

Hyperspectral infrared radiance measurements from satellite sensors contain valuable information on atmospheric temperature and humidity profiles and greenhouse gases, and therefore are directly assimilated into numerical weather prediction (NWP) models as inputs for weather forecasting. However, data assimilations in current operational NWP models still mainly rely on cloud-free observations due to the challenge of simulating cloud-contaminated radiances when using hyperspectral radiances. The limited spatial coverage of the 3×3 field of views (FOVs) in one field of regard (FOR) (i.e., spatial gap among FOVs) as well as relatively large footprint size (14 km) in current Cross-track Infrared Sounder (CrIS) instruments limits the amount of clear-sky observations. This study explores the potential impacts of future CrIS FOV configuration (including FOV size and spatial coverage) on the amount of clear-sky observations by simulation experiments. The radiance measurements and cloud mask products (VCM) from the Visible Infrared Imager Radiometer Suite (VIIRS) are used to simulate CrIS clear-sky observation under different FOV configurations. The results indicate that, given the same FOV coverage (e.g., 3×3), the percentage of clear-sky FOVs and the percentage of clear-sky FORs (that contain at least one clear-sky FOV) both increase as the FOV size decreases. In particular, if the CrIS FOV size were reduced from 14 km to 7 km, the percentage of clear-sky FOVs increases from 9.02% to 13.51% and the percentage of clear-sky FORs increases from 18.24% to 27.51%. Given the same FOV size but with increasing FOV coverage in each FOR, the clear-sky FOV observations increases proportionally with the increasing sampling FOVs. Both reducing FOV size and increasing FOV coverage can result in more clear-sky FORs, which benefit data utilization of NWP data assimilation.

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".

VizieR Online Data Catalog: λ Bootis stars: the southern survey I. (Gray+, 2017)

NASA Astrophysics Data System (ADS)

Gray, R. O.; Riggs, Q. S.; Koen, C.; Murphy, S. J.; Newsome, I. M.; Corbally, C. J.; Cheng, K.-P.; Neff, J. E.

2017-10-01

Observations were carried out with the South African Astronomical Observatory (SAAO) SpCCD grating spectrograph, attached to the SAAO 1.9m telescope. Grating 6 was employed, which yields a resolution of about 2Å/2 pixels and a spectral range from 3600 to 5400Å. Time was granted for four observing runs of about 5 days each in 2013 December, and 2014 March, June, and September, enabling us to cover the entire southern sky. A total of 291 program stars, plus a number of MK standards, were observed over the four runs. (6 data files).

True-sky demonstration of an autonomous star tracker

NASA Astrophysics Data System (ADS)

van Bezooijen, Roelof W.

1994-07-01

An autonomous star tracker (AST) is basically a `star field in, attitude out' device capable of determining its attitude without requiring any a priori attitude knowledge. In addition to this attitude acquisition capability, an AST can perform attitude updates autonomously and is able to provide its attitude `continuously' while tracking a star field. The Lockheed Palo Alto Research Laboratory is developing a reliable, low-cost, miniature AST that has a one arcsec overall accuracy, weighs less than 1.5 kg, consumes less than 7 watts of power, and is sufficiently sensitive to be used at all sky locations. The device performs attitude acquisition in a fraction of a second and outputs its attitude at a 10 Hz rate when operating in its tracking mode. Besides providing the functionality needed for future advanced attitude control and navigation systems, an AST also improves spacecraft reliability, mass, power, cost, and operating expenses. The AST comprises a-thermalized, refractive optics, a frame-transfer CCD with a sensitive area of 1024 by 1024 pixels, camera electronics implemented with application- specific integrated circuits, a compact single board computer with a radiation hard 32 bit RISC processor, and an all-sky guide star database. Star identification is performed by a memory- efficient and highly robust algorithm that finds the largest group of observed stars matching a group of guide stars. An important milestone has recently been achieved with the validation of the attitude acquisition capability through correct and rapid identification of all 704 true-sky star fields obtained at the Lick Observatory, using an uncalibrated prototype AST with a 512 by 1024 pixel frame-transfer CCD and a 50 mm f/1.2 lens that provided an effective 6.5 by 13.2 degree field of view. The overlapping fields cover 47% of the sky, including both rich and sparse areas. The paper contains a description of the AST, a summary of the functions enabled or improved by the device, an

Winter sky brightness & cloud cover over Dome A

NASA Astrophysics Data System (ADS)

Yang, Yi; Moore, A. M.; Fu, J.; Ashley, M.; Cui, X.; Feng, L.; Gong, X.; Hu, Z.; Laurence, J.; LuongVan, D.; Riddle, R. L.; Shang, Z.; Sims, G.; Storey, J.; Tothill, N.; Travouillon, T.; Wang, L.; Yang, H.; Yang, J.; Zhou, X.; Zhu, Z.; Burton, M. G.

2014-01-01

At the summit of the Antarctic plateau, Dome A offers an intriguing location for future large scale optical astronomical Observatories. The Gattini DomeA project was created to measure the optical sky brightness and large area cloud cover of the winter-time sky above this high altitude Antarctic site. The wide field camera and multi-filter system was installed on the PLATO instrument module as part of the Chinese-led traverse to Dome A in January 2008. This automated wide field camera consists of an Apogee U4000 interline CCD coupled to a Nikon fish-eye lens enclosed in a heated container with glass window. The system contains a filter mechanism providing a suite of standard astronomical photometric filters (Bessell B, V, R), however, the absence of tracking systems, together with the ultra large field of view 85 degrees) and strong distortion have driven us to seek a unique way to build our data reduction pipeline. We present here the first measurements of sky brightness in the photometric B, V, and R band, cloud cover statistics measured during the 2009 winter season and an estimate of the transparency. In addition, we present example light curves for bright targets to emphasize the unprecedented observational window function available from this ground-based location. A ~0.2 magnitude agreement of our simultaneous test at Palomar Observatory with NSBM(National Sky Brightness Monitor), as well as an 0.04 magnitude photometric accuracy for typical 6th magnitude stars limited by the instrument design, indicating we obtained reasonable results based on our ~7mm effective aperture fish-eye lens.

Aerosol radiative effects and their trends under clear-sky situations over Europe

NASA Astrophysics Data System (ADS)

Bartok, Blanka

2017-04-01

In the literature great uncertainties ca be found regarding radiative effects of aerosols on the energy budget of the atmosphere (IPCC, 2013). In the study the aerosols radiative effects on clear-sky solar radiation are quantified over Europe using empirical and physical modelling approaches. The values of aerosol radiation effect are determined by the MAGIC radiation code. In the first run clear-sky radiation is calculated integrating KINEE/MPI/Aerocom aerosol climatology and ERA-INTERIM water vapour multiannual monthly means. In the next run the clear-sky radiation are also calculated ignoring aerosol data (adjusted to 0) from the algorithm. Both runs were carried out for each months of the year, taking into account the varying astrological factors. The difference between the aerosol-included and aerosol-free clear-sky radiation is equal to the absolute aerosol radiative effect in W/m2. The annual mean of the surface aerosol radiative effects in clear-sky situations over Europe is -7.1 ± 2.9 W/m2, high values are representing the central part of the continent and the Mediterranean Basin. Furthermore the trends of the aerosol radiative effects are also determined for the period of 2001-2012. First a linear fitting is elaborated between the aerosol optical depth (AOT) built in the MAGIC code and its aerosol radiative effect calculated by the code. Next, based on these linear functions a radiative effect values are assigned to each monthly AOT500 value available from the Moderate Resolution Imaging Spectroradiometer (MODIS) Terra Level-3 experiment. In this way a new dataset of aerosol radiative effect for the period of 2001-2012 has been created. Beside of this approach the changes in aerosol radiative effects are also calculated based on ground-based clear-sky radiation trends. This approach is used as a validation of the method applied in earlier stage, mainly for the linear fitting. The starting point of this approach is to elaborate the trends of clear-sky

Results from the Ariel-5 all-sky X-ray monitor

NASA Technical Reports Server (NTRS)

Holt, S. S.

1975-01-01

A summary of results obtained from the first year of Ariel-5 all-sky monitor operation is presented. Transient source observations, as well as the results of long term studies of Sco X-1, Cyg X-3, and Cyg X-1 are described. By example, the included results are indicative of the temporal effects to which the all-sky monitor remains sensitive as it begins its second year of observation.

Correlated noise in the COBE DMR sky maps

NASA Technical Reports Server (NTRS)

Lineweaver, C. H.; Smoot, G. F.; Bennett, C. L.; Wright, E. L.; Tenorio, L.; Kogut, A.; Keegstra, P. B.; Hinshaw, G.; Banday, A. J.

1994-01-01

The Cosmic Background Explorer Satellite Differential Radiometer (COBE DMR) sky maps contain low-level correlated noise. We obtain estimates of the amplitude and pattern of the correlated noise from three techniques: angular averages of the covariance matrix, Monte Carlo simulations of two-point correlation functions and direct analysis of the DMR maps. The results from the three methods are mutually consistent. The noise covariance matrix of a DMR sky maps is diagonal to an accuracy of better than 1%. For a given sky pixel, the dominant noise covariance occure with the ring of pixels at an angular separation of 60 deg due to the 60 deg separation of the DMR horns. The mean covariance at 60 deg is 0.45%((sup +0.18)(sub -0.14)) of the mean variance. Additionally, the variance in a given pixel is 0.7% greater than would be expected from a single beam experiment with the same noise properties. Autocorrelation functions suffer from a approximately 1.5 sigma positive bias at 60 deg while cross-correlations have no bias. Published COBE DMR results are not significantly affected by correlated noise.

PRIMORDIAL GRAVITATIONAL WAVE DETECTABILITY WITH DEEP SMALL-SKY COSMIC MICROWAVE BACKGROUND EXPERIMENTS

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

Farhang, M.; Bond, J. R.; Netterfield, C. B.

2013-07-01

We use the Bayesian estimation on direct T - Q - U cosmic microwave background (CMB) polarization maps to forecast errors on the tensor-to-scalar power ratio r, and hence on primordial gravitational waves, as a function of sky coverage f{sub sky}. This map-based likelihood filters the information in the pixel-pixel space into the optimal combinations needed for r detection for cut skies, providing enhanced information over a first-step linear separation into a combination of E, B, and mixed modes, and ignoring the latter. With current computational power and for typical resolutions appropriate for r detection, the large matrix inversions requiredmore » are accurate and fast. Our simulations explore two classes of experiments, with differing bolometric detector numbers, sensitivities, and observational strategies. One is motivated by a long duration balloon experiment like Spider, with pixel noise {proportional_to}{radical}(f{sub sky}) for a specified observing period. This analysis also applies to ground-based array experiments. We find that, in the absence of systematic effects and foregrounds, an experiment with Spider-like noise concentrating on f{sub sky} {approx} 0.02-0.2 could place a 2{sigma}{sub r} Almost-Equal-To 0.014 boundary ({approx}95% confidence level), which rises to 0.02 with an l-dependent foreground residual left over from an assumed efficient component separation. We contrast this with a Planck-like fixed instrumental noise as f{sub sky} varies, which gives a Galaxy-masked (f{sub sky} = 0.75) 2{sigma}{sub r} Almost-Equal-To 0.015, rising to Almost-Equal-To 0.05 with the foreground residuals. Using as the figure of merit the (marginalized) one-dimensional Shannon entropy of r, taken relative to the first 2003 WMAP CMB-only constraint, gives -2.7 bits from the 2012 WMAP9+ACT+SPT+LSS data, and forecasts of -6 bits from Spider (+ Planck); this compares with up to -11 bits for CMBPol, COrE, and PIXIE post-Planck satellites and -13 bits for a

Protecting Dark Skies as a State-Wide Resource

NASA Astrophysics Data System (ADS)

Allen, Lori E.; Walker, Constance E.; Hall, Jeffrey C.; Larson, Steve; Williams, Grant; Falco, Emilio; Hinz, Joannah; Fortin, Pascal; Brocious, Dan; Corbally, Christopher; Gabor, Paul; Veillet, Christian; Shankland, Paul; Jannuzi, Buell; Cotera, Angela; Luginbuhl, Christian

2018-01-01

The state of Arizona contains the highest concentration of research telescopes in the continental United States, contributing more than a quarter of a billion dollars annually to the state's economy. Protecting the dark skies above these observatories is both good for astronomy and good for the state's economy. In this contribution we describe how a coalition of Arizona observatories is working together to protect our dark skies. Efforts date back to the creation of one of the first Outdoor Lighting Codes in the United States and continue today, including educational outreach, public policy engagement, and consensus building. We review some proven strategies, highlight recent successes and look at current threats.

Near infrared photographic sky survey - A field index

NASA Technical Reports Server (NTRS)

Rossano, G. S.; Craine, E. R.

1980-01-01

The book presents an index of previously cataloged objects located in the fields of the northern sky included in the Steward Observatory Near Infrared Photographic Sky Survey, which was intended to be used for identification purposes in an effort to locate extremely red objects. The objects included in the index were taken from 16 catalogs of bright nebulae, dark nebulae, infrared objects, reflection nebulae, supernova remnants and other objects, and appear with their corresponding field numbers, computed field center coordinates, object name and 1950 epoch equatorial coordinates, as well as supplementary descriptive information as available. An appendix is also provided in which the center coordinates of each field are listed.

Diamonds in the Sky

NASA Astrophysics Data System (ADS)

Brotherton, M.

2004-12-01

My first science fiction novel, Star Dragon, just recently available in paperback from Tor, features a voyage to the cataclysmic variable star system SS Cygni. My second novel, Spider Star, to appear early in 2006, takes place in and around a dark matter ``planet'' orbiting a neutron star. Both novels are ``hard'' science fiction, relying on accurate physics to inform the tales. It's possible to bring to life abstract concepts like special relativity, and alien environments like accretion disks, by using science fiction. Novels are difficult to use in a science class, but short stories offer intriguing possibilities. I'm planning to edit an anthology of hard science fiction stories that contain accurate science and emphasize fundamental ideas in modern astronomy. The working title is Diamonds in the Sky. The collection will be a mix of original stories and reprints, highlighting challenging concepts covered in a typical introductory astronomy course. Larry Niven's classic story, ``Neutron Star," is an excellent demonstration of extreme tidal forces in an astronomical context. Diamonds in the Sky will include forewards and afterwards to the stories, including discussion questions and mathematical formulas/examples as appropriate. I envision this project will be published electronically or through a print-on-demand publisher, providing long-term availabilty and keeping low cost. I encourage interested parties to suggest previously published stories, or to suggest which topics must be included.

Estimation of clear-sky insolation using satellite and ground meteorological data

NASA Technical Reports Server (NTRS)

Staylor, W. F.; Darnell, W. L.; Gupta, S. K.

1983-01-01

Ground based pyranometer measurements were combined with meteorological data from the Tiros N satellite in order to estimate clear-sky insolations at five U.S. sites for five weeks during the spring of 1979. The estimates were used to develop a semi-empirical model of clear-sky insolation for the interpretation of input data from the Tiros Operational Vertical Sounder (TOVS). Using only satellite data, the estimated standard errors in the model were about 2 percent. The introduction of ground based data reduced errors to around 1 percent. It is shown that although the errors in the model were reduced by only 1 percent, TOVS data products are still adequate for estimating clear-sky insolation.

The Potential of Clear Sky Carbon Dioxide Satellite Retrievals

NASA Astrophysics Data System (ADS)

Nelson, R.; O'Dell, C.

2013-12-01

It has been shown that neglecting scattering and absorption by aerosols and thin clouds can lead to significant errors in retrievals of the column-averaged dry-air mole fraction of carbon dioxide (XCO2) from space-based measurements of near-infrared reflected sunlight. These clear sky retrievals, which assume no aerosol effects, are desirable because of their high computational efficiency relative to common full physics retrievals. Further, clear sky retrievals may be able to make higher quality measurements relative to the full physics approach because they may introduce fewer potential biases under certain circumstances. These biases can appear when we try to retrieve clouds and aerosols in the full physics methods when there are none actually present. Recent work has shown that intelligent pre-screening can remove soundings with large light-path modifications over ocean surfaces. In this work, we test the hypothesis that intelligent pre-screening of soundings may be successfully used over land surfaces as well as oceans, which would allow clear sky retrievals to be applicable over all surfaces. We also test the hypothesis that major light path modification effects associated with aerosols can be identified based on spectral tests at 0.76, 1.6, and 2 microns. This presentation summarizes our study of both simulated data and satellite observations from the GOSAT instrument in order to assess the effectiveness of using a clear sky retrieval algorithm coupled with intelligent pre-screening to accurately measure carbon dioxide from space-borne instruments.

Quantifying the clear-sky bias of satellite-derived infrared LST

NASA Astrophysics Data System (ADS)

Ermida, S. L.; Trigo, I. F.; DaCamara, C.

2017-12-01

Land surface temperature (LST) is one of the most relevant parameters when addressing the physical processes that take place at the surface of the Earth. Satellite data are particularly appropriate for measuring LST over the globe with high temporal resolution. Remote-sensed LST estimation from space-borne sensors has been systematically performed over the Globe for nearly 3 decades and geostationary LST climate data records are now available. The retrieval of LST from satellite observations generally relies on measurements in the thermal infrared (IR) window. Although there is a large number of IR sensors on-board geostationary satellites and polar orbiters suitable for LST retrievals with different temporal and spatial resolutions, the use of IR observations limits LST estimates to clear sky conditions. As a consequence, climate studies based on IR LST are likely to be affected by the restriction of LST data to cloudless conditions. However, such "clear sky bias" has never been quantified and, therefore, the actual impact of relying only on clear sky data is still to be determined. On the other hand, an "all-weather" global LST database may be set up based on passive microwave (MW) measurements which are much less affected by clouds. An 8-year record of all-weather MW LST is here used to quantify the clear-sky bias of IR LST at global scale based on MW observations performed by the Advanced Microwave Scanning Radiometer-Earth Observing System (AMSR-E) onboard NASA's Aqua satellite. Selection of clear-sky and cloudy pixels is based on information derived from measurements performed by the Moderate Resolution Imaging Spectroradiometer (MODIS) on-board the same satellite.

The spectral amplification effect of clouds to the night sky radiance in Madrid

NASA Astrophysics Data System (ADS)

Aubé, M.; Kocifaj, M.; Zamorano, J.; Solano Lamphar, H. A.; Sanchez de Miguel, A.

2016-09-01

Artificial Light at Night (ALAN) may have various environmental impacts ranging from compromising the visibility of astronomical objects to the perturbation of circadian cycles in animals and humans. In the past much research has been carried out to study the impact of ALAN on the radiance of the night sky during clear sky conditions. This was mainly justified by the need for a better understanding of the behavior of ALAN propagation into the environment in order to protect world-class astronomical facilities. More recently, alongside to the threat to the natural starry sky, many issues have emerged from the biological science community. It has been shown that, nearby or inside cities, the presence of cloud cover generally acts as an amplifier for artificial sky radiance while clouds behave as attenuators for remote observers. In this paper we show the spectral behavior of the zenith sky radiance amplification factor exerted by clouds inside a city. We compare in-situ measurements made with the spectrometer SAND-4 with a numerical model applied to the specific geographical context of the Universidad Complutense de Madrid in Spain.

Measuring the influence of aerosols and albedo on sky polarization.

PubMed

Kreuter, A; Emde, C; Blumthaler, M

2010-11-01

All-sky distributions of the polarized radiance are measured using an automated fish-eye camera system with a rotating polarizer. For a large range of aerosol and surface albedo situations, the influence on the degree of polarization and sky radiance is investigated. The range of aerosol optical depth and albedo is 0.05-0.5 and 0.1-0.75, respectively. For this range of parameters, a reduction of the degree of polarization from about 0.7 to 0.4 was observed. The analysis is done for 90° scattering angle in the principal plane under clear sky conditions for a broadband channel of 450 ± 25 nm and solar zenith angles between 55° and 60°. Radiative transfer calculations considering three different aerosol mixtures are performed and and agree with the measurements within the statistical error.

Introducing the All-sky NOAO Source Catalog

NASA Astrophysics Data System (ADS)

Nidever, David L.; NOAO DataLab

2017-06-01

Most of the sky has been imaged with NOAO's telescopes from both hemispheres. While the large majority of these data were obtained for PI-led projects only a small fraction have been released to the community via well-calibrated and easily accessible catalogs. We are remedying this by created a catalog of sources from most of the public data taken on CTIO-4m+DECam as well as KPNO-4m+Mosaic3. This catalog, called the NOAO Source Catalog (NSC), already contains 2.3 billion unique objects, 19 billion source measurements, covers ~25,000 square degrees of the sky, has 10-sigma depths of ~23rd magnitude in most broadband filters, and astrometric accuracy of ~20 mas. We plan to release the catalog via the new NOAO Data Lab service in the near future.

Sacred Sky and Cyberspace

NASA Astrophysics Data System (ADS)

Clynes, F.

2011-06-01

The concept of the sacred world beyond the stars found expression in the works of Plato, into Gnosticism and was incorporated into Christianity where medieval images of the cosmos pictured the heavenly domain as beyond the stars. Today cyberspace literature abounds with descriptions of a transmundane space, a great Beyond. This talk looks at current views of cyberspace and asks if they are a re-packaging of the age-old concept of a sacred sky in a secular and technological format?

77 FR 50065 - Safety Zone; Jacksonville Sea and Sky Spectacular, Atlantic Ocean; Jacksonville Beach, FL

Federal Register 2010, 2011, 2012, 2013, 2014

2012-08-20

... 1625-AA00 Safety Zone; Jacksonville Sea and Sky Spectacular, Atlantic Ocean; Jacksonville Beach, FL... during the Jacksonville Sea and Sky Spectacular air show. The event is scheduled to take place from....T07-0660 Safety Zone; Jacksonville Sea and Sky Spectacular, Atlantic Ocean, Jacksonville Beach, FL. (a...

A Sky Chock-Full of Black Holes

NASA Image and Video Library

2012-08-29

With its all-sky infrared survey, NASA Wide-field Infrared Survey Explorer, or WISE, has identified millions of quasar candidates. Quasars are supermassive black holes with masses millions to billions times greater than our sun.

Infrared Astronomical Satellite View of the Sky

NASA Image and Video Library

2009-11-03

Nearly the entire sky, as seen in infrared wavelengths and projected at one-half degree resolution, is shown in this image, assembled from six months of data from the NASA Infrared Astronomical Satellite, or IRAS.

MEqTrees Telescope and Radio-sky Simulations and CPU Benchmarking

NASA Astrophysics Data System (ADS)

Shanmugha Sundaram, G. A.

2009-09-01

MEqTrees is a Python-based implementation of the classical Measurement Equation, wherein the various 2×2 Jones matrices are parametrized representations in the spatial and sky domains for any generic radio telescope. Customized simulations of radio-source sky models and corrupt Jones terms are demonstrated based on a policy framework, with performance estimates derived for array configurations, ``dirty''-map residuals and processing power requirements for such computations on conventional platforms.

Cone of Darkness: Finding Blank-sky Positions for Multi-object Wide-field Observations

NASA Astrophysics Data System (ADS)

Lorente, N. P. F.

2014-05-01

We present the Cone of Darkness, an application to automatically configure blank-sky positions for a series of stacked, wide-field observations, such as those carried out by the SAMI instrument on the Anglo-Australian Telescope (AAT). The Sydney-AAO Multi-object Integral field spectrograph (SAMI) uses a plug-plate to mount its 13×61 core imaging fibre bundles (hexabundles) in the optical plane at the telescope's prime focus. To make the most efficient use of each plug-plate, several observing fields are typically stacked to produce a single plate. When choosing blank-sky positions for the observations it is most effective to select these such that one set of 26 holes gives valid sky positions for all fields on the plate. However, when carried out manually this selection process is tedious and includes a significant risk of error. The Cone of Darkness software aims to provide uniform blank-sky position coverage over the field of observation, within the limits set by the distribution of target positions and the chosen input catalogs. This will then facilitate the production of the best representative median sky spectrum for use in sky subtraction. The application, written in C++, is configurable, making it usable for a range of instruments. Given the plate characteristics and the positions of target holes, the software segments the unallocated space on the plate and determines the position which best fits the uniform distribution requirement. This position is checked, for each field, against the selected catalog using a TAP ADQL search. The process is then repeated until the desired number of sky positions is attained.

The fast transient sky with Gaia

NASA Astrophysics Data System (ADS)

Wevers, Thomas; Jonker, Peter G.; Hodgkin, Simon T.; Kostrzewa-Rutkowska, Zuzanna; Harrison, Diana L.; Rixon, Guy; Nelemans, Gijs; Roelens, Maroussia; Eyer, Laurent; van Leeuwen, Floor; Yoldas, Abdullah

2018-01-01

The ESA Gaia satellite scans the whole sky with a temporal sampling ranging from seconds and hours to months. Each time a source passes within the Gaia field of view, it moves over 10 charge coupled devices (CCDs) in 45 s and a light curve with 4.5 s sampling (the crossing time per CCD) is registered. Given that the 4.5 s sampling represents a virtually unexplored parameter space in optical time domain astronomy, this data set potentially provides a unique opportunity to open up the fast transient sky. We present a method to start mining the wealth of information in the per CCD Gaia data. We perform extensive data filtering to eliminate known onboard and data processing artefacts, and present a statistical method to identify sources that show transient brightness variations on ≲2 h time-scales. We illustrate that by using the Gaia photometric CCD measurements, we can detect transient brightness variations down to an amplitude of 0.3 mag on time-scales ranging from 15 s to several hours. We search an area of ∼23.5 deg2 on the sky and find four strong candidate fast transients. Two candidates are tentatively classified as flares on M-dwarf stars, while one is probably a flare on a giant star and one potentially a flare on a solar-type star. These classifications are based on archival data and the time-scales involved. We argue that the method presented here can be added to the existing Gaia Science Alerts infrastructure for the near real-time public dissemination of fast transient events.

Getting Students to Observe the Night Sky, Even When Your Sky is Cloudy Half the Time

NASA Astrophysics Data System (ADS)

Shipman, Harry L.

2010-01-01

Teachers of introductory astronomy classes often wish to get our students to look at the night sky However, most educational institutions in America are located in regions where cloudy nights are relatively common. This paper describes a low cost way to integrate observations into a course which lacks a dedicated astronomy lab. Students in two large. general science classes in fall 2008 and spring 2009 were asked to participate in one of two global star-counting projects. The fall project was coordinated by UCAR and asked for observations of the constellation Cygnus (http://www.windows.ucar.edu/citizen_science/starcount/results.html). The spring project was run by Project Globe and asked for observations of the constellation Orion. (http://www.globe.gov/GaN/ ). In both cases, students simply find the constellation, match the star pattern to charts that go to different limiting magnitudes, and report the data to the coordinating organization. A copy of the report is sent to the course instructor. The instructor can ask for additional information. Did it work? The success of this project was evaluated by analyzing the e-mail messages that students returned in response to the assignment. In both courses, a very large majority of the students actually did the exercise and submitted a report. Students reported that observing the sky in this way was satisfying to them., and sometimes the reports were quite enthusiastic. In spring 2009, some preparatory activies were conducted during class that were designed to sensitize students to the beauty of the sky. Analysis of student reports indicated that these preparatory activities were helpful, but not as helpful as the instructor would like. This research is part of the Teacher Professional Continuum project at the University of Delaware, which is supported by the National Science Foundation.

Dark Skies Awareness Cornerstone Project for the International Year of Astronomy

NASA Astrophysics Data System (ADS)

Walker, C. E.; Pompea, S. M.; Iya Dark Skies Awareness Working Group

2010-12-01

Programs that were part of the International Year of Astronomy 2009 (IYA2009) Dark Skies Awareness (DSA) Cornerstone Project have been successfully implemented around the world to promote social awareness of the effects of light pollution on public health, economic issues, ecological consequences, energy conservation, safety and security, nightscape aesthetics and especially astronomy. In developing the programs, DSA Cornerstone Project found that to influence cultural change effectively — to make people literally look up and see the light — we must make children a main focus, use approaches that offer involvement on many levels, from cursory to committed, and offer involvement via many venues. We must make the programs and resources as turn-key as possible, especially for educators — and provide ways to visualize the problem with simple, easily grasped demonstrations. The programs spanned a wide range; from new media technology for the younger generation, to an event in the arts, to various types of educational materials, to the promotion of dark skies communities, to national and international events and to global citizen science programs. The DSA Cornerstone Project is continuing most all of these programs beyond IYA2009. The International Dark-Sky Association as well as the Starlight Initiative is endorsing and helping to continue with some of the most successful programs from the DSA. The GLOBE at Night campaign is adding a research component that examines light pollution’s affects on wildlife. Dark Skies Rangers activities are being implemented in Europe through the Galileo Teacher Training Program. The new “One Star at a Time” will engage people to protect the night sky through personal pledges and registration of public stargazing areas or StarParks, like the newest one in Italy. The Starlight Initiative’s World Night in Defence of the Starlight will take place on the Vernal Equinox. DSA will again oversee the Dark Skies portion of Global

Night Sky Brightness Measurement by the Public through a Mobile Phone App

NASA Astrophysics Data System (ADS)

Kamegai, Kazuhisa; Tsukada, Ken; Inoue, Hiroki

2015-08-01

The darkness of night sky is important naturally for astronomy researchers, and also for the public people. Particularly, it is meaningful for those who begin to have an interest in gazing stars. Some previous studies suggest that light pollution may affect human health and ecosystem in various ways. Furthermore, it causes a lot of waste of electric energy for lighting.In Japan, the night sky brightness had been measured by Ministry of Environment for a few decades. Recently some global efforts have been also conducted. However the number of measured position is limited because the measurement needs some apparatus and takes long time.Here we show a result of quick and easy measurements of night sky brightness by the public people through a mobile phone app. The measurements were conducted in cooperation between some members of the Tenpla project and a weather forecasting company. The app has been developed by the company and has been installed by over 6.5 million people, which allow us to get a large number of data. Our purposes are (1) making map of night sky brightness all over Japan and (2) providing an opportunity to enjoy gazing star for those who are not usually interested in astronomy.As an interactive function of the app, we put a questionnaire of four choices in which we ask users how many stars are visible in a part of the constellation of Orion. When users answer the question, we get the answer and the position where they are. Depending on the answer, we can roughly recognize the sky brightness of the position.We opened the measurements for several nights. As a result, we could get 4000 - 5000 data all over the country per night. The map of each night is a snapshot of sky brightness of the night including effect of the weather. For example we can recognize that the sky is getting darker as a function of distance from the metropolitan area of Tokyo. We will show the detail results in the presentation.

The Sky This Week, 2016 April 5 - 12 - Naval Oceanography Portal

Science.gov Websites

section Advanced Search... Sections Home Time Earth Orientation Astronomy Meteorology Oceanography Ice You to the evening sky this week, with New Moon falling on the 7th at 7:24 am Eastern Daylight Time. Try . Take some time this week to consider the night sky and the wonderful resource that it truly is. During

Local effects of partly cloudy skies on solar and emitted radiations

NASA Technical Reports Server (NTRS)

Whitney, D. A.; Venable, D. D.

1981-01-01

Solar radiation measurements are made on a routine basis. Global solar, atmospheric emitted, downwelled diffuse solar, and direct solar radiation measurement systems are fully operational with the first two in continuous operation. Fractional cloud cover measurements are made from GOES imagery or from ground based whole sky photographs. Normalized global solar irradiance values for partly cloudy skies were correlated to fractional cloud cover.

Anomalous celestial polarization caused by forest fire smoke: why do some insects become visually disoriented under smoky skies?

NASA Astrophysics Data System (ADS)

Hegedüs, Ramón; Åkesson, Susanne; Horváth, Gábor

2007-05-01

The effects of forest fire smoke on sky polarization and animal orientation are practically unknown. Using full-sky imaging polarimetry, we therefore measured the celestial polarization pattern under a smoky sky in Fairbanks, Alaska, during the forest fire season in August 2005. It is quantitatively documented here that the celestial polarization, a sky attribute that is necessary for orientation of many polarization-sensitive animal species, above Fairbanks on 17 August 2005 was in several aspects anomalous due to the forest fire smoke: (i) The pattern of the degree of linear polarization p of the reddish smoky sky differed considerably from that of the corresponding clear blue sky. (ii) Due to the smoke, p of skylight was drastically reduced (pmax≤14%, paverage≤8%). (iii) Depending on wavelength and time, the Arago, Babinet, and Brewster neutral points of sky polarization had anomalous positions. We suggest that the disorientation of certain insects observed by Canadian researchers under smoky skies during the forest fire season in August 2003 in British Columbia was the consequence of the anomalous sky polarization caused by the forest fire smoke.

Statistical Properties of a Two-Stage Procedure for Creating Sky Flats

NASA Astrophysics Data System (ADS)

Crawford, R. W.; Trueblood, M.

2004-05-01

Accurate flat fielding is an essential factor in image calibration and good photometry, yet no single method for creating flat fields is both practical and effective in all cases. At Winer Observatory, robotic telescope opera- tion and the research program of Near Earth Object follow-up astrometry favor the use of sky flats formed from the many images that are acquired during a night. This paper reviews the statistical properties of the median-combine process used to create sky flats and discusses a computationally efficient procedure for two-stage combining of many images to form sky flats with relatively high signal-to-noise ratio (SNR). This procedure is in use at Winer for the flat field calibration of unfiltered images taken for NEO follow-up astrometry.

Map of low-frequency electromagnetic noise in the sky

NASA Astrophysics Data System (ADS)

Füllekrug, Martin; Mezentsev, Andrew; Watson, Robert; Gaffet, Stéphane; Astin, Ivan; Smith, Nathan; Evans, Adrian

2015-06-01

The Earth's natural electromagnetic environment is disturbed by anthropogenic electromagnetic noise. Here we report the first results from an electromagnetic noise survey of the sky. The locations of electromagnetic noise sources are mapped on the hemisphere above a distributed array of wideband receivers that operate in a small aperture configuration. It is found that the noise sources can be localized at elevation angles up to ˜60° in the sky, well above the horizon. The sky also exhibits zones with little or no noise that are found toward the local zenith and the southwest of the array. These results are obtained by a rigorous analysis of the residuals from the classic dispersion relation for electromagnetic waves using an array analysis of electric field measurements in the frequency range from ˜20 to 250 kHz. The observed locations of the noise sources enable detailed observations of ionospheric modification, for example, caused by particle precipitation and lightning discharges, while the observed exclusion zones enable the detection of weak natural electromagnetic emissions, for example, from streamers in transient luminous events above thunderclouds.

Galactic SNR Candidates in the ROSAT All-Sky Survey

NASA Technical Reports Server (NTRS)

Schaudel, Daniel; Becker, Werner; Voges, Wolfgand; Reich, Wolfgang; Weisskopf, Martin; Six, N. Frank (Technical Monitor)

2001-01-01

Identified radio supernova remnants (SNRS) in the Galaxy comprise an incomplete sample of the SNR population due to various selection effects. ROSAT performed the first all-sky survey with an imaging X-ray telescope, and thus provides another window for finding SNRS and compact objects that may reside within them. Performing a search for extended X-ray sources in the ROSAT all-sky survey database about 350 objects were identified as SNR candidates in recent years. Continuing this systematic search, we have reanalyzed the ROSAT all-sky survey (BASS) data of these candidates and correlated the results with radio surveys like NVSS, ATNF, Molonglo, and Effelsberg. A further correlation with SIMBAD and NED were used for subsequent identification purpose. About 50 of the 350 candidates turned out to be likely galaxies or clusters of galaxies. We found 14 RASS sources which are very promising SNR candidates and are currently subject of further follow-up studies. We will provide the details of the identification campaign and present first results.

ESO unveils an amazing, interactive, 360-degree panoramic view of the entire night sky

NASA Astrophysics Data System (ADS)

2009-09-01

, 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

Sky distribution of artificial sources in the galactic belt of advanced cosmic life.

PubMed

Heidmann, J

1994-12-01

In line with the concept of the galactic belt of advanced life, we evaluate the sky distribution of detectable artificial sources, using a simple astrophysical model. The best region to search is the median band of the Milky Way in the Vulpecula-Cygnus region, together with a narrower one in Carina. Although this work was done in view of a proposal to send a SETI probe at a gravitational focus of the Sun, we recommend these sky regions particularly for the searches of the sky survey type.

Measuring the influence of aerosols and albedo on sky polarization

PubMed Central

Kreuter, A.; Emde, C.; Blumthaler, M.

2010-01-01

All-sky distributions of the polarized radiance are measured using an automated fish-eye camera system with a rotating polarizer. For a large range of aerosol and surface albedo situations, the influence on the degree of polarization and sky radiance is investigated. The range of aerosol optical depth and albedo is 0.05–0.5 and 0.1–0.75, respectively. For this range of parameters, a reduction of the degree of polarization from about 0.7 to 0.4 was observed. The analysis is done for 90° scattering angle in the principal plane under clear sky conditions for a broadband channel of 450 ± 25 nm and solar zenith angles between 55° and 60°. Radiative transfer calculations considering three different aerosol mixtures are performed and and agree with the measurements within the statistical error. PMID:24068851

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.

SkyProbe, monitoring the absolute atmospheric transmission in the optical

NASA Astrophysics Data System (ADS)

Cuillandre, Jean-charles; Magnier, Eugene; Mahoney, William

2011-03-01

Mauna Kea is known for its pristine seeing conditions, but sky transparency can be an issue for science operations since 25% of the night are not photometric, mostly due to high-altitude cirrus. Since 2001, the original single-channel SkyProbe has gathered one exposure every minute during each observing night using a small CCD camera with a very wide field of view (35 sq. deg.) encompassing the region pointed by the telescope for science operations, and exposures long enough (40 seconds) to capture at least 100 stars of Hipparcos' Tychos catalog at high galactic latitudes (and up to 600 stars at low galactic latitudes). A key advantage of SkyProbe over direct thermal infrared imaging detection of clouds, is that it allows an accurate absolute measurement, within 5%, of the true atmospheric absorption by clouds affecting the data being gathered by the telescope's main science instrument. This system has proven crucial for decision making in the CFHT queued service observing (QSO), representing today 80% of the telescope time: science exposures taken in non-photometric conditions are automatically registered for being re-observed later on (at 1/10th of the original exposure time per pointing in the observed filters) to ensure a proper final absolute photometric calibration. The new dual color system (simultaneous B&V bands) will allow a better characterization of the sky properties atop Mauna Kea and will enable a better detection of the thinner cirrus (absorption down to 0.02 mag., i.e. 2%). SkyProbe is operated within the Elixir pipeline, a collection of tools used for handling the CFHT CCD mosaics (CFH12K and MegaCam), from data pre-processing to astrometric and photometric calibration.

Ultra-Stable Spectrometer for Sky-Scanning, Sun-Tracking Atmospheric Research (5STAR)

NASA Technical Reports Server (NTRS)

Dunagan, Stephen E.; Johnson, Roy R.; Redemann, Jens; Holben, Brent N.; Schmidt, Beat; Flynn, Connor Joseph; Fahey, Lauren; LeBlanc, Samuel; Liss, Jordan; Kacenelenbogen, Meloe S.;

Overview of the SkyMed/COSMO mission

NASA Astrophysics Data System (ADS)

Caltagirone, Francesco; Spera, Paolo; Vigliotti, R.; Manoni, Gemma

1998-12-01

The impact of natural and man-made disasters on the social and economic progress is going to become more significant, making necessary to consider natural disasters reduction. Therefore civil protection and resource managers need elements to make quicker and better decisions on a day-to-day basis, so giving the start to an emerging world-wide remote sensing market. A deep analysis on the potential users, mainly devoted to Mediterranean basin, highlights that existing and/or planned systems are not able to completely satisfy their requirements. To fulfill this gap, Italy decided to promote the SkyMed/COSMO system, presently financed by the Italian Space Agency. SkyMed/COSMO is a constellation of small satellites for observation, remote sensing and data exploitation for risks management and coastal zone monitoring, conceived to provide products, services and logistics to both institutional and commercial remote sensing users on global scale. Furthermore the system is able to satisfy a broad spectrum of important applications also in the field of the resource management, land use and law enforcement. The SkyMed/COSMO current system architecture foresees a constellation of small satellites in two different orbit planes composed by 4 satellite equipped with X-band SAR and 3 satellites equipped with optical sensors. The system is characterized by good spatial resolution, day and night/all-weather imaging capability and by a very good revisit time. The program, currently in phase B, is carried out by an industrial consortium lead by Alenia Aerospazio.

Educational Aspects of the CONCAM Sky Monitoring Project

NASA Astrophysics Data System (ADS)

Nemiroff, R. J.; Rafert, J. B.; Ftaclas, C.; Pereira, W. E.; Perez-Ramirez, D.

2000-12-01

We have built a prototype CONtinuous CAMera (CONCAM) that mates a fisheye lens to a CCD camera run by a laptop computer. Presently, one CONCAM is deployed at Kitt Peak National Observatory and another is being set up on Mauna Kea in Hawaii. CONCAMs can detect stars of visual magnitude 6 near the image center in a two-minute exposure. CONCAMs are weather-proof, take continuous data from 2 π steradians on the sky, are programmable over the internet, create data files downloadable over the internet, are small enough to fit inside a briefcase, and cost under \\$10 K. . Images archived at http://concam.net can be used to teach many introductory concepts. These include: the rotation of the Earth, the relative location and phase of the Moon, the location and relative motion of planets, the location of the Galactic plane, the motion of Earth satellites, the location and motion of comets, the motion of meteors, the radiant of a meteor shower, the relative locations of interesting stars, and the relative brightness changes of highly variable stars. Concam.net is not meant to replace first hand student observations of the sky, but rather to complement them with classroom-accessible actual-sky-image examples.

INTEGRAL/IBIS 7-year All-Sky Hard X-ray Survey. I. Image reconstruction

NASA Astrophysics Data System (ADS)

Krivonos, R.; Revnivtsev, M.; Tsygankov, S.; Sazonov, S.; Vikhlinin, A.; Pavlinsky, M.; Churazov, E.; Sunyaev, R.

2010-09-01

This paper is the first in a series devoted to the hard X-ray whole sky survey performed by the INTEGRAL observatory over seven years. Here we present an improved method for image reconstruction with the IBIS coded mask telescope. The main improvements are related to the suppression of systematic effects that strongly limit sensitivity in the region of the Galactic plane (GP), especially in the crowded field of the Galactic center (GC). We extended the IBIS/ISGRI background model to take into account the Galactic ridge X-ray emission (GRXE). To suppress residual systematic artifacts on a reconstructed sky image, we applied nonparametric sky image filtering based on wavelet decomposition. The implemented modifications of the sky reconstruction method decrease the systematic noise in the ~20 Ms deep field of GC by ~44%, and practically remove it from the high-latitude sky images. New observational data sets, along with an improved reconstruction algorithm, allow us to conduct the hard X-ray survey with the best currently available minimal sensitivity 3.7 × 10-12 erg s-1 cm-2 ~ 0.26 mCrab in the 17-60 keV band at a 5σ detection level. The survey covers 90% of the sky down to the flux limit of 6.2 × 10-11 erg s-1 cm-2 (~4.32 mCrab) and 10% of the sky area down to the flux limit of 8.6 × 10-12 erg s-1 cm-2 (~0.60 mCrab). Based on observations with INTEGRAL, an ESA project with the instruments and science data center funded by ESA member states (especially the PI countries: Denmark, France, Germany, Italy, Switzerland, Spain), Czech Republic, and Poland, and with the participation of Russia and the USA.

A Review of Optical Sky Brightness and Extinction at Dome C, Antarctica

NASA Astrophysics Data System (ADS)

Kenyon, S. L.; Storey, J. W. V.

2006-03-01

The recent discovery of exceptional seeing conditions at Dome C, Antarctica, raises the possibility of constructing an optical observatory there with unique capabilities. However, little is known from an astronomer's perspective about the optical sky brightness and extinction at Antarctic sites. We review the contributions to sky brightness at high-latitude sites and calculate the amount of usable dark time at Dome C. We also explore the implications of the limited sky coverage of high-latitude sites and review optical extinction data from the South Pole. Finally, we examine the proposal of Baldry & Bland-Hawthorn to extend the amount of usable dark time through the use of polarizing filters.

Fire history and moisture influences on historical forest age structure in the sky islands of southern Arizona, USA

Treesearch

Jose M. Iniguez; Thomas W. Swetnam; Christopher H. Baisan

2016-01-01

Aim: The purpose of this study was to examine the influence of moisture and fire on historical ponderosa pine (Pinus ponderosa Dougl. ex Laws.) age structure patterns. Location: We used a natural experiment created over time by the unique desert island geography of southern Arizona. Methods: We sampled tree establishment dates in two sites on Rincon Peak and...

Hubble Sees a Silver Needle in the Sky

NASA Image and Video Library

2014-08-22

This stunning new image from the NASA/ESA Hubble Space Telescope shows part of the sky in the constellation of Canes Venatici (The Hunting Dogs). Although this region of the sky is not home to any stellar heavyweights, being mostly filled with stars of average brightness, it does contain five Messier objects and numerous intriguing galaxies — including NGC 5195, a small barred spiral galaxy considered to be one of the most beautiful galaxies visible, and its nearby interacting partner the Whirlpool Galaxy (heic0506a). The quirky Sunflower Galaxy is another notable galaxy in this constellation, and is one of the largest and brightest edge-on galaxies in our skies. Joining this host of characters is spiral galaxy NGC 4244, nicknamed the Silver Needle Galaxy, shown in this new image from Hubble. This galaxy spans some 65,000 light-years and lies around 13.5 million light-years away. It appears as a wafer-thin streak across the sky, with loosely wound spiral arms hidden from view as we observe the galaxy from the side. It is part of a group of galaxies known as the M94 Group. Numerous bright clumps of gas can be seen scattered across its length, along with dark dust lanes surrounding the galaxy’s core. NGC 4244 also has a bright star cluster at its center. Although we can make out the galaxy’s bright central region and star-spattered arms, we cannot see any more intricate structure due to the galaxy’s position; from Earth, we see it stretched out as a flattened streak across the sky. A number of different observations were pieced together to form this mosaic, and gaps in Hubble’s coverage have been filled in using ground-based data. The Hubble observations were taken as part of the Galaxy Halos, Outer disks, Substructure, Thick disks and Star clusters (GHOSTS) survey, which is scanning nearby galaxies to explore how they and their stars formed to get a more complete view of the history of the Universe. European Space Agency Credit: NASA & ESA, Acknowledgement

A Comprehensive Approach to Dark Skies Research and Education at NOAO

NASA Astrophysics Data System (ADS)

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

2013-01-01

NOAO and its Education and Public Outreach group play an important role locally, nationally, and internationally in raising dark skies awareness. For the past 3 years NOAO has co-hosted the international “Earth and Sky” photo contest. In 2012 there were over 600 entries contributed within 3 weeks. NOAO also created a series of audio podcasts based on serial-type skits featuring a caped dark-skies hero who typically “saves the night” by mitigating upward directed lights with shields, thereby saving sea turtles, minimizing health effects, conserving energy, or keeping the public safe. To help understand the effects of light pollution, a citizen-science campaign called GLOBE at Night was started seven years ago. The worldwide campaign involves the public in recording night sky brightness data by matching the view of a constellation like Orion with maps of progressively fainter stars. Every year, NOAO adds more opportunities for participation: more campaigns during the year, Web applications for smart phones, objective measurements with sky brightness meters, and a GLOBE at Night Facebook page. Campaigns will run roughly the first 10 days of January through May in 2013. The EPO group created “Dark Skies Rangers”, a suite of well-tested and evaluated hands-on, minds-on activities that have children building star-brightness “readers,” creating glow-in-the-dark tracings to visualize constellations, and role-playing confused sea turtles. They also created a model city with shielded lights to stop upward light, examine different kinds of bulbs for energy efficiency, and perform an outdoor lighting audit of their school or neighborhood to determine ways to save energy. In the REU program at NOAO North, the undergraduate students have been doing research over the last 3 summers on effect of light pollution on endangered bats and characterizing the behavior of sky brightness over time across Tucson and on nearby astronomical mountaintops. For more information

The van Gogh of the Infrared Sky

NASA Image and Video Library

2011-04-25

NASA Wide-field Infrared Survey Explorer is a little like the Vincent van Gogh of the infrared sky, providing the world with picturesque images of the cosmos by representing infrared light through color. This image is the nebula NGC 2174.

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.

Under the Same Sky

NASA Astrophysics Data System (ADS)

Ratajczak, Milena

2016-07-01

Sharing the same sky provides the unique opportunity to use it as a tool to inspire pupils and encourage them to develop an interest in science and technology. Excitement of space can also serve as introduction to the idea of global citizenship and tolerance. A wide spectrum of educational activities dedicated to children and teenagers, especially those from less privileged backgrounds, carried out under several projects in Poland will be presented. We will also introduce the way we follow to support teachers and educators in discovering our wonderful cosmos.

Whole Sky Imager Characterization of Sky Obscuration by Clouds for the Starfire Optical Range

DTIC Science & Technology

2010-01-11

9.3 Further Algorithm Development and Evaluation 58 9.4 Analysis of the Data Base 58 10.0 DISCUSSION OF CONTRACT REQUIREMENTS 59 10.1...clouds, Site 5 Feb 14 2008 0900 28 21 Transmittance map, Moonlight , clear sky, Site 5 Feb 3 2008 0700 28 22 Transmittance map, Moonlight , thin...clouds, Site 5 Feb 8 2008 1200 29 23 Transmittance map, Moonlight , broken clouds, Site 5 Feb 2 2008 0800 29 24 Cloud Algorithm Results, Moonlight

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

Anthropogenic disruption of the night sky darkness in urban and rural areas.

PubMed

Bará, Salvador

2016-10-01

The growing emissions of artificial light to the atmosphere are producing, among other effects, a significant increase of the night sky brightness (NSB) above its expected natural values. A permanent sensor network has been deployed in Galicia (northwest of Iberian peninsula) to monitor the anthropogenic disruption of the night sky darkness in a countrywide area. The network is composed of 14 detectors integrated in automated weather stations of MeteoGalicia, the Galician public meteorological agency. Zenithal NSB readings are taken every minute and the results are openly available in real time for researchers, interested stakeholders and the public at large through a dedicated website. The measurements allow one to assess the extent of the loss of the natural night in urban, periurban, transition and dark rural sites, as well as its daily and monthly time courses. Two metrics are introduced here to characterize the disruption of the night darkness across the year: the significant magnitude ( m 1/3 ) and the moonlight modulation factor ( γ ). The significant magnitude shows that in clear and moonless nights the zenithal night sky in the analysed urban settings is typically 14-23 times brighter than expected from a nominal natural dark sky. This factor lies in the range 7-8 in periurban sites, 1.6-2.5 in transition regions and 0.8-1.6 in rural and mountain dark sky places. The presence of clouds in urban areas strongly enhances the amount of scattered light, easily reaching amplification factors in excess of 25, in comparison with the light scattered in the same places under clear sky conditions. The periodic NSB modulation due to the Moon, still clearly visible in transition and rural places, is barely notable at periurban locations and is practically lost at urban sites.

ultra-Stable Spectrometer for Sky-Scanning, Sun-Tracking Atmospheric Research (5STAR)

NASA Astrophysics Data System (ADS)

Dunagan, S. E.; Johnson, R. R.; Redemann, J.; Holben, B. N.; Schmid, B.; Flynn, C. J.; Fahey, L.; LeBlanc, S. E.; Liss, J.; Kacenelenbogen, M. S.; Segal-Rosenhaimer, M.; Shinozuka, Y.; Dahlgren, R. P.; Pistone, K.; Karol, Y.

2017-12-01

The Spectrometer for Sky-Scanning, Sun-Tracking Atmospheric Research (4STAR) combines airborne sun tracking and sky scanning with diffraction spectroscopy to improve knowledge of atmospheric constituents and their links to air pollution and climate. Direct beam hyperspectral measurement of optical depth improves retrievals of gas constituents and determination of aerosol properties. Sky scanning enhances retrievals of aerosol type and size distribution. Hyperspectral cloud-transmitted radiance measurements enable the retrieval of cloud properties from below clouds. These measurements tighten the closure between satellite and ground-based measurements. 4STAR incorporates a modular sun-tracking/ sky-scanning optical head with optical fiber signal transmission to rack mounted spectrometers, permitting miniaturization of the external optical tracking head, and future detector evolution. 4STAR has supported a broad range of flight experiments since it was first flown in 2010. This experience provides the basis for a series of improvements directed toward reducing measurement uncertainty and calibration complexity, and expanding future measurement capabilities, to be incorporated into a new 5STAR instrument. A 9-channel photodiode radiometer with AERONET-matched bandpass filters will be incorporated to improve calibration stability. A wide dynamic range tracking camera will provide a high precision solar position tracking signal as well as an image of sky conditions around the solar axis. An ultrasonic window cleaning system design will be tested. A UV spectrometer tailored for formaldehyde and SO2 gas retrievals will be added to the spectrometer enclosure. Finally, expansion capability for a 4 channel polarized radiometer to measure the Stokes polarization vector of sky light will be incorporated. This paper presents initial progress on this next-generation 5STAR instrument. Keywords: atmosphere; climate; pollution; radiometry; technology; hyperspectral; fiber optic

Anthropogenic disruption of the night sky darkness in urban and rural areas

PubMed Central

2016-01-01

The growing emissions of artificial light to the atmosphere are producing, among other effects, a significant increase of the night sky brightness (NSB) above its expected natural values. A permanent sensor network has been deployed in Galicia (northwest of Iberian peninsula) to monitor the anthropogenic disruption of the night sky darkness in a countrywide area. The network is composed of 14 detectors integrated in automated weather stations of MeteoGalicia, the Galician public meteorological agency. Zenithal NSB readings are taken every minute and the results are openly available in real time for researchers, interested stakeholders and the public at large through a dedicated website. The measurements allow one to assess the extent of the loss of the natural night in urban, periurban, transition and dark rural sites, as well as its daily and monthly time courses. Two metrics are introduced here to characterize the disruption of the night darkness across the year: the significant magnitude (m1/3) and the moonlight modulation factor (γ). The significant magnitude shows that in clear and moonless nights the zenithal night sky in the analysed urban settings is typically 14–23 times brighter than expected from a nominal natural dark sky. This factor lies in the range 7–8 in periurban sites, 1.6–2.5 in transition regions and 0.8–1.6 in rural and mountain dark sky places. The presence of clouds in urban areas strongly enhances the amount of scattered light, easily reaching amplification factors in excess of 25, in comparison with the light scattered in the same places under clear sky conditions. The periodic NSB modulation due to the Moon, still clearly visible in transition and rural places, is barely notable at periurban locations and is practically lost at urban sites. PMID:27853572

Deep Sky Diving with the ESO New Technology Telescope

NASA Astrophysics Data System (ADS)

1998-01-01

Caption to ESO PR Photo 01/98 and access to two versions of the photo The frames were computer processed and combined to yield a colour view of the corresponding sky field ( ESO Press Photo 01/98 ). This is indeed a very deep look into the southern sky. The astronomers have found that the limiting magnitude (at a signal-to-noise ratio of 3) is beyond 27 in the blue and red frames and only slightly brighter in the two others. Magnitude 27 corresponds to a brightness that is 250 million times fainter than what can be perceived with the unaided eye. Although not as deep as the Hubble Deep Field due to the shorter exposure time and brighter sky background (caused by light emission in the upper layers of the terrestrial atmosphere), this new set of data is among the best ground-based observations of this type ever obtained. Galaxies down to a magnitude of roughly 25 will soon be targets of detailed spectroscopic observations with the VLT. They will provide a measure of their basic physical parameters like redshift, luminosity and mass. How to access the new data This scientific program aims at the study of the photometric redshift distribution of the faint galaxies [2] and of gravitational lensing effects (cosmic mirages). It has been decided to make the complete data set available to the wide scientific community and it is expected that many astronomers all over the world will want to perform their own investigations by means of this unique observational material. A full description of the project is available on the ESO Web at http://www.eso.org/ndf/. Here you will find a comprehensive explanation of the scientific background, details about the observations and the data reduction, as well as easy access to the corresponding data files. Notes: [1] The group consists of Sandro D'Odorico (Principal Investigator, ESO) and Jacqueline Bergeron (ESO), Hans-Martin Adorf (ESO), Stephane Charlot (IAP, Paris, France), David Clements (IAS, Orsay, France), Stefano Cristiani (Univ. of

Influence of Sky Conditions on Estimation of Photosynthetic Photon Flux Density for Agricultural Ecosystem

NASA Astrophysics Data System (ADS)

Yamashita, M.; Yoshimura, M.

2018-04-01

Photosynthetic photon flux density (PPFD: µmol m-2 s-1) is indispensable for plant physiology processes in photosynthesis. However, PPFD is seldom measured, so that PPFD has been estimated by using solar radiation (SR: W m-2) measured in world wide. In method using SR, there are two steps: first to estimate photosynthetically active radiation (PAR: W m-2) by the fraction of PAR to SR (PF) and second: to convert PAR to PPFD using the ratio of quanta to energy (Q / E: µmol J-1). PF and Q/E usually have been used as the constant values, however, recent studies point out that PF and Q / E would not be constants under various sky conditions. In this study, we use the numeric data of sky-conditions factors such cloud cover, sun appearance/hiding and relative sky brightness derived from whole-sky image processing and examine the influences of sky-conditions factors on PF and Q / E of global and diffuse PAR. Furthermore, we discuss our results by comparing with the existing methods.

The AST3 controlling and operating software suite for automatic sky survey

NASA Astrophysics Data System (ADS)

Hu, Yi; Shang, Zhaohui; Ma, Bin; Hu, Keliang

2016-07-01

We have developed a specialized software package, called ast3suite, to achieve the remote control and automatic sky survey for AST3 (Antarctic Survey Telescope) from scratch. It includes several daemon servers and many basic commands. Each program does only one single task, and they work together to make AST3 a robotic telescope. A survey script calls basic commands to carry out automatic sky survey. Ast3suite was carefully tested in Mohe, China in 2013 and has been used at Dome, Antarctica in 2015 and 2016 with the real hardware for practical sky survey. Both test results and practical using showed that ast3suite had worked very well without any manual auxiliary as we expected.

Assessment of clear sky radiative fluxes in CMIP5 climate models using surface observations from BSRN

NASA Astrophysics Data System (ADS)

Wild, M.; Hakuba, M. Z.; Folini, D.; Ott, P.; Long, C. N.

2017-12-01

Clear sky fluxes in the latest generation of Global Climate Models (GCM) from CMIP5 still vary largely particularly at the Earth's surface, covering in their global means a range of 16 and 24 Wm-2 in the surface downward clear sky shortwave (SW) and longwave radiation, respectively. We assess these fluxes with monthly clear sky reference climatologies derived from more than 40 Baseline Surface Radiation Network (BSRN) sites based on Long and Ackermann (2000) and Hakuba et al. (2015). The comparison is complicated by the fact that the monthly SW clear sky BSRN reference climatologies are inferred from measurements under true cloud-free conditions, whereas the GCM clear sky fluxes are calculated continuously at every timestep solely by removing the clouds, yet otherwise keeping the prevailing atmospheric composition (e.g. water vapor, temperature, aerosols) during the cloudy conditions. This induces the risk of biases in the GCMs just due to the additional sampling of clear sky fluxes calculated under atmospheric conditions representative for cloudy situations. Thereby, a wet bias may be expected in the GCMs compared to the observational references, which may induce spurious low biases in the downward clear sky SW fluxes. To estimate the magnitude of these spurious biases in the available monthly mean fields from 40 CMIP5 models, we used their respective multi-century control runs, and searched therein for each month and each BSRN station the month with the lowest cloud cover. The deviations of the clear sky fluxes in this month from their long-term means have then be used as indicators of the magnitude of the abovementioned sampling biases and as correction factors for an appropriate comparison with the BSRN climatologies, individually applied for each model and BSRN site. The overall correction is on the order of 2 Wm-2. This revises our best estimate for the global mean surface downward SW clear sky radiation, previously at 249 Wm-2 infered from the GCM clear sky

Mitigation of Volcanic Risk: The COSMO-SkyMed Contribution

NASA Astrophysics Data System (ADS)

Sacco, Patrizia; Daraio, Maria Girolamo; Battagliere, Maria Libera; Coletta, Alessandro

2015-05-01

The Italian Space Agency (ASI) promotes Earth Observation (EO) applications related to themes such as the prediction, monitoring, management and mitigation of natural and anthropogenic hazards. The approach generally followed is the development and demonstration of prototype services, using currently available data from space missions, in particular the COSMO-SkyMed (Constellation of Small Satellites for Mediterranean basin observation) mission, which represents the largest Italian investment in Space System for EO and thanks to which Italy plays a key role worldwide. Projects funded by ASI provide the convergence of various national industry expertise, research and institutional reference users. In this context a significant example is represented by the ASI Pilot Projects, recently concluded, dealing with various thematic, such as volcanoes. In this paper a special focus will be addressed to the volcanic risk management and the contribution provided in this field by COSMO-SkyMed satellite constellation during the last years. A comprehensive overview of the various national and international projects using COSMO-SkyMed data for the volcanic risk mitigation will be given, highlighting the Italian contribution provided worldwide in this operational framework.

Clear-sky narrowband albedos derived from VIRS and MODIS

NASA Astrophysics Data System (ADS)

Sun-Mack, Sunny; Minnis, Patrick; Chen, Yan; Arduini, Robert F.

2004-02-01

The Clouds and Earth"s Radiant Energy System (CERES) project is using multispectral imagers, the Visible Infrared Scanner (VIRS) on the tropical Rainfall Measuring Mission (TRMM) satellite and the Moderate Resolution Imaging Spectroradiometer (MODIS) on Terra, operating since spring 2000, and Aqua, operating since summer 2002, to provide cloud and clear-sky properties at various wavelengths. This paper presents the preliminary results of an analysis of the CERES clear-sky reflectances to derive a set top-of-atmosphere clear sky albedo for 0.65, 0.86, 1.6, 2.13 μm, for all major surface types using the combined MODIS and VIRS datasets. The variability of snow albedo with surface type is examined using MODIS data. Snow albedo was found to depend on the vertical structure of the vegetation. At visible wavelengths, it is least for forested areas and greatest for smooth desert and tundra surfaces. At 1.6 and 2.1-μm, the snow albedos are relatively insensitive to the underlying surface because snow decreases the reflectance. Additional analyses using all of the MODIS results will provide albedo models that should be valuable for many remote sensing, simulation and radiation budget studies.

Dual energy micro CT SkyScan 1173 for the characterization of urinary stone

NASA Astrophysics Data System (ADS)

Fitri, L. A.; Asyana, V.; Ridwan, T.; Anwary, F.; Soekersi, H.; Latief, F. D. E.; Haryanto, F.

2016-03-01

Knowledge of the composition of urinary stones is an essential part to determine suitable treatments for patients. The aim of this research is to characterize the urinary stones by using dual energy micro CT SkyScan 11173. This technique combines high-energy and low- energy scanning during a single acquisition. Six human urinary stones were scanned in vitro using 80 kV and 120 kV micro CT SkyScan 1173. Projected images were produced by micro CT SkyScan 1173 and then reconstructed using NRecon (in-house software from SkyScan) to obtain a complete 3D image. The urinary stone images were analysed using CT analyser to obtain information of internal structure and Hounsfield Unit (HU) values to determine the information regarding the composition of the urinary stones, respectively. HU values obtained from some regions of interest in the same slice are compared to a reference HU. The analysis shows information of the composition of the six scanned stones obtained. The six stones consist of stone number 1 (calcium+cystine), number 2 (calcium+struvite), number 3 (calcium+cystine+struvite), number 4 (calcium), number 5 (calcium+cystine+struvite), and number 6 (calcium+uric acid). This shows that dual energy micro CT SkyScan 1173 was able to characterize the composition of the urinary stone.

Scalable nuclear density functional theory with Sky3D

NASA Astrophysics Data System (ADS)

Afibuzzaman, Md; Schuetrumpf, Bastian; Aktulga, Hasan Metin

2018-02-01

In nuclear astrophysics, quantum simulations of large inhomogeneous dense systems as they appear in the crusts of neutron stars present big challenges. The number of particles in a simulation with periodic boundary conditions is strongly limited due to the immense computational cost of the quantum methods. In this paper, we describe techniques for an efficient and scalable parallel implementation of Sky3D, a nuclear density functional theory solver that operates on an equidistant grid. Presented techniques allow Sky3D to achieve good scaling and high performance on a large number of cores, as demonstrated through detailed performance analysis on a Cray XC40 supercomputer.

The All-Sky Automated Survey for Supernovae

NASA Astrophysics Data System (ADS)

Bersier, D.

2016-12-01

This is an overview of the All-Sky Automated Survey for SuperNovae - ASAS-SN. We briefly present the hardware and capabilities of the survey and describe the most recent science results, in particular tidal disruption events and supernovae, including the brightest SN ever found.

Lens Systems for Sky Surveys and Space Surveillance

NASA Astrophysics Data System (ADS)

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

2013-09-01

Since the early days of astrophotography, lens systems have played a key role in capturing images of the night sky. The first images were attempted with visual-refractors. These were soon followed with color-corrected refractors and finally specially designed photo-refractors. Being telescopes, these instruments were of long-focus and imaged narrow fields of view. Simple photographic lenses were soon put into service to capture wide-field images. These lenses also had the advantage of requiring shorter exposure times than possible using large refractors. Eventually, lenses were specifically designed for astrophotography. With the introduction of the Schmidt-camera and related catadioptric systems, the popularity of astrograph lenses declined, but surprisingly, a few remained in use. Over the last 30 years, as small CCDs have displaced large photographic plates, lens systems have again found favor for their ability to image great swaths of sky in a relatively small and simple package. In this paper, we follow the development of lens-based astrograph systems from their beginnings through the current use of both commercial and custom lens systems for sky surveys and space surveillance. Some of the optical milestones discussed include the early Petzval-type portrait lenses, the Ross astrographic lens and the current generation of optics such as the commercial 200mm camera lens by Canon, and the Russian VT-53e in service with ISON.

New species in the Sitalcina sura species group (Opiliones, Laniatores, Phalangodidae), with evidence for a biogeographic link between California desert canyons and Arizona sky islands.

PubMed

DiDomenico, Angela; Hedin, Marshal

2016-01-01

The western United States is home to numerous narrowly endemic harvestman taxa (Arachnida, Opiliones), including members of the genus Sitalcina Banks, 1911. Sitalcina is comprised of three species groups, including the monospecific Sitalcina californica and Sitalcina lobata groups, and the Sitalcina sura group with eight described species. All species in the Sitalcina sura group have very small geographic distributions, with group members distributed like disjunct "beads on a string" from Monterey south to southern California and southeast to the sky-island mountain ranges of southern Arizona. Here, molecular phylogenetic and species delimitation analyses were conducted for all described species in the Sitalcina sura group, plus several newly discovered populations. Species trees were reconstructed using multispecies coalescent methods implemented in *BEAST, and species delimitation was accomplished using Bayes Factor Delimitation (BFD). Based on quantitative species delimitation results supported by consideration of morphological characters, two new species (Sitalcina oasiensis sp. n., Sitalcina ubicki sp. n.) are described. We also provide a description of the previously unknown male of Sitalcina borregoensis Briggs, 1968. Molecular phylogenetic evidence strongly supports distinctive desert versus coastal clades, with desert canyon taxa from southern California more closely related to Arizona taxa than to geographically proximate California coastal taxa. We hypothesize that southern ancestry and plate tectonics have played a role in the diversification history of this animal lineage, similar to sclerophyllous plant taxa of the Madro-Tertiary Geoflora. Molecular clock analyses for the Sitalcina sura group are generally consistent with these hypotheses. We also propose that additional Sitalcina species await discovery in the desert canyons of southern California and northern Baja, and the mountains of northwestern mainland Mexico.

New species in the Sitalcina sura species group (Opiliones, Laniatores, Phalangodidae), with evidence for a biogeographic link between California desert canyons and Arizona sky islands

PubMed Central

DiDomenico, Angela; Hedin, Marshal

2016-01-01

Abstract The western United States is home to numerous narrowly endemic harvestman taxa (Arachnida, Opiliones), including members of the genus Sitalcina Banks, 1911. Sitalcina is comprised of three species groups, including the monospecific Sitalcina californica and Sitalcina lobata groups, and the Sitalcina sura group with eight described species. All species in the Sitalcina sura group have very small geographic distributions, with group members distributed like disjunct “beads on a string” from Monterey south to southern California and southeast to the sky-island mountain ranges of southern Arizona. Here, molecular phylogenetic and species delimitation analyses were conducted for all described species in the Sitalcina sura group, plus several newly discovered populations. Species trees were reconstructed using multispecies coalescent methods implemented in *BEAST, and species delimitation was accomplished using Bayes Factor Delimitation (BFD). Based on quantitative species delimitation results supported by consideration of morphological characters, two new species (Sitalcina oasiensis sp. n., Sitalcina ubicki sp. n.) are described. We also provide a description of the previously unknown male of Sitalcina borregoensis Briggs, 1968. Molecular phylogenetic evidence strongly supports distinctive desert versus coastal clades, with desert canyon taxa from southern California more closely related to Arizona taxa than to geographically proximate California coastal taxa. We hypothesize that southern ancestry and plate tectonics have played a role in the diversification history of this animal lineage, similar to sclerophyllous plant taxa of the Madro-Tertiary Geoflora. Molecular clock analyses for the Sitalcina sura group are generally consistent with these hypotheses. We also propose that additional Sitalcina species await discovery in the desert canyons of southern California and northern Baja, and the mountains of northwestern mainland Mexico. PMID:27199607

Variability of AVHRR-Derived Clear-Sky Surface Temperature over the Greenland Ice Sheet.

NASA Astrophysics Data System (ADS)

Stroeve, Julienne; Steffen, Konrad

1998-01-01

The Advanced Very High Resolution Radiometer is used to derive surface temperatures for one satellite pass under clear skies over the Greenland ice sheet from 1989 through 1993. The results of these temperatures are presented as monthly means, and their spatial and temporal variability are discussed. Accuracy of the dry snow surface temperatures is estimated to be better than 1 K during summer. This error is expected to increase during polar night due to problems in cloud identification. Results indicate the surface temperature of the Greenland ice sheet is strongly dominated by topography, with minimum surface temperatures associated with the high elevation regions. In the summer, maximum surface temperatures occur during July along the western coast and southern tip of the ice sheet. Minimum temperatures are found at the summit during summer and move farther north during polar night. Large interannual variability in surface temperatures occurs during winter associated with katabatic storm events. Summer temperatures show little variation, although 1992 stands out as being colder than the other years. The reason for the lower temperatures during 1992 is believed to be a result of the 1991 eruption of Mount Pinatubo.

Polarization of 'water-skies' above arctic open waters: how polynyas in the ice-cover can be visually detected from a distance.

PubMed

Hegedüs, Ramón; Akesson, Susanne; Horváth, Gábor

2007-01-01

The foggy sky above a white ice-cover and a dark water surface (permanent polynya or temporary lead) is white and dark gray, phenomena called the 'ice-sky' and the 'water-sky,' respectively. Captains of icebreaker ships used to search for not-directly-visible open waters remotely on the basis of the water sky. Animals depending on open waters in the Arctic region may also detect not-directly-visible waters from a distance by means of the water sky. Since the polarization of ice-skies and water-skies has not, to our knowledge, been studied before, we measured the polarization patterns of water-skies above polynyas in the arctic ice-cover during the Beringia 2005 Swedish polar research expedition to the North Pole region. We show that there are statistically significant differences in the angle of polarization between the water-sky and the ice-sky. This polarization phenomenon could help biological and man-made sensors to detect open waters not directly visible from a distance. However, the threshold of polarization-based detection would be rather low, because the degree of linear polarization of light radiated by water-skies and ice-skies is not higher than 10%.

"Untangling the centimetre-wavelength sky"

NASA Astrophysics Data System (ADS)

Leahy, J. Patrick

2015-08-01

The global SED of the Milky Way reaches a minimum at about 80 GHz. In the decade below this, three emission processes predominate: synchrotron, from cosmic ray leptons spiralling in the Galactic magnetic field; free-free, from ionized gas in nebulae and the diffuse warm ionized medium; and anomalous microwaves (AME), believed to be dipole emission from spinning very small dust grains. Each component provides unique diagnostics: synchroton traces the lepton energy spectrum near 20 GeV and reveals the local and global structure of the Galactic magnetic field, free-free probes ionized gas where the usual H-alpha tracer is obscured, and AME traces a new interstellar component, whose relation to the general dust population can now be explored. In total intensity, accurate separation of these components is a hard problem not yet completely solved, mainly due to the spatial variability of the AME spectrum, which in the Planck 2015 analysis dominates the SED between 20 and 60 GHz. New large-area surveys in the frequency decade below the satellite microwave will, in combination with Planck and WMAP, will provide a far more robust determination of each component.In contrast to the confused situation in total intensity, only synchrotron contributes significant polarization in our band, and WMAP and Planck give a clear view of the polarized synchrotron sky, for the first time effectively free of Faraday rotation and depolarization. New ground-based microwave polarization surveys such as GMIMS, S-PASS, C-BASS, and QUIJOTE, will add much higher sensitivity and also have the high frequency resolution needed to trace the line-of-sight component of the magnetic field via Faraday synthesis. The polarization along the Galactic plane constrains models of the global Galactic magnetic field. Away from the plane, polarization probes the tangling of the field in the Galactic halo and clarifies the structure of the Galactic loops and spurs, which impose a large-scale coherence on the

Does Flattened Sky Dome Reduces Perceived Moon Size

NASA Astrophysics Data System (ADS)

Toskovic, O.

2009-09-01

The aim of this study was to examine the Flattened sky dome model as an explanation of the Moon illusion. Two experiments were done, in a dark room, in which distribution of depth cues is the same towards horizon as towards zenith. In the first experiment 14 participants had the task to equalize the perceived distances of three stimuli in three directions (horizontal, tilted 45 degrees and vertical). In the second experiment 16 participants had the task to estimate the perceived sizes of three stimuli in the same three directions. For distance estimates we found differences among three directions in a way, that as the head tilts upwards, the perceived space is being elongated, which is the opposite to flattened sky dome. For size estimates we found no difference among the three directions.