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

Correcting the relationship between PRI and shadow fraction for the blue sky effect

NASA Astrophysics Data System (ADS)

Mõttus, Matti

2016-04-01

The Photochemical Reflectance Index (PRI) is defined as the normalized difference ratio of leaf reflectance at two specific wavelengths in the green spectral region. Its value depends on the status of leaf carotenoid content, and especially that of the xanthophyll cycle pigments. Due to the dependence on the xanthophyll cycle, when the photosynthetic apparatus of green leaves is close to the saturation limit, their PRI becomes dependent on light conditions. Therefore, by measuring the PRI of leaves in the same canopy under different local irradiance conditions on a sunny day, it should be possible to determine the saturation level of the leaves. In turn, this gives information on the light use efficiency (LUE) of the vegetation canopy. The average light conditions of visible foliage elements are often quantified with the shadow fraction -- the fraction of visible foliage not lit by direct sunlight. The dependence of PRI on the shadow fraction has been used to remotely measure canopy LUE on clear days. Variations in shadow fraction have been achieved with multiangular measurement. However, besides photosynthetic downregulation, the dependence of canopy PRI on shadow fraction is affected by the blue sky radiation caused by scattering in the atmosphere. To quantify this effect on remotely sensed PRI, we present the underlying definitions relating leaf and canopy PRI and perform the required calculations for typical midsummer conditions in Central Finland. We demonstrate that the effect of blue sky radiation on the variation of PRI with canopy shadow fraction is similar in shape and magnitude to that of LUE variations reported in literature. Next, we propose a new method to assess these PRI variations in structured vegetation. We investiagate this blue sky effect on the PRI -- shadow fraction relationship with high spatial (60 cm) and spectral (9.8 nm) resolution airborne imaging spectroscopy data from Hyytiälä, Finland. We evaluate the spectral irradiance in

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

NASA Astrophysics Data System (ADS)

McNeil, B.

2014-12-01

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

Pluto Blue Sky

NASA Image and Video Library

2015-10-08

Pluto's haze layer shows its blue color in this picture taken by the New Horizons Ralph/Multispectral Visible Imaging Camera (MVIC). The high-altitude haze is thought to be similar in nature to that seen at Saturn's moon Titan. The source of both hazes likely involves sunlight-initiated chemical reactions of nitrogen and methane, leading to relatively small, soot-like particles (called tholins) that grow as they settle toward the surface. This image was generated by software that combines information from blue, red and near-infrared images to replicate the color a human eye would perceive as closely as possible. http://photojournal.jpl.nasa.gov/catalog/PIA19964

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…

Comparison of modified Chicago sky blue stain and potassium hydroxide mount for the diagnosis of dermatomycoses and onychomycoses.

PubMed

Liu, Zhong; Sheng, Ping; Yang, Yan-Ping; Li, Wen; Huang, Wen-Ming; Wang, Jie-Di; Fan, Yi-Ming

2015-05-01

The diagnostic value of modified Chicago sky blue (CSB) stain and potassium hydroxide (KOH) mount for superficial mycoses was compared using fungal culture as gold standard. The sensitivity and screening time of the CSB stain were superior to the KOH mount. The CBS stain is simple, quick and reliable for diagnosing superficial mycoses. Copyright © 2015. Published by Elsevier B.V.

Non-Doped Sky-Blue OLEDs Based on Simple Structured AIE Emitters with High Efficiencies at Low Driven Voltages.

PubMed

Islam, Amjad; Zhang, Dongdong; Peng, Ruixiang; Yang, Rongjuan; Hong, Ling; Song, Wei; Wei, Qiang; Duan, Lian; Ge, Ziyi

2017-09-05

Blue organic light-emitting diodes (OLEDs) are necessary for flat-panel display technologies and lighting applications. To make more energy-saving, low-cost and long-lasting OLEDs, efficient materials as well as simple structured devices are in high demand. However, a very limited number of blue OLEDs achieving high stability and color purity have been reported. Herein, three new sky-blue emitters, 1,4,5-triphenyl-2-(4-(1,2,2-triphenylvinyl)phenyl)-1H-imidazole (TPEI), 1-(4-methoxyphenyl)-4,5-diphenyl-2-(4-(1,2,2-triphenylvinyl)phenyl)-1H-imidazole (TPEMeOPhI) and 1-phenyl-2,4,5-tris(4-(1,2,2-triphenylvinyl)phenyl)-1H-imidazole (3TPEI), with a combination of imidazole and tetraphenylethene groups, have been developed. High photoluminescence quantum yields are obtained for these materials. All derivatives have demonstrated aggregation-induced emission (AIE) behavior, excellent thermal stability with high decomposition and glass transition temperatures. Non-doped sky-blue OLEDs with simple structure have been fabricated employing these materials as emitters and realized high efficiencies of 2.41 % (4.92 cd A -1 , 2.70 lm W -1 ), 2.16 (4.33 cd A -1 , 2.59 lm W -1 ) and 3.13 % (6.97 cd A -1 , 4.74 lm W -1 ) for TPEI, TPEMeOPhI and 3TPEI, with small efficiency roll-off. These are among excellent results for molecules constructed from the combination of imidazole and TPE reported so far. The high performance of a 3TPEI-based device shows the promising potential of the combination of imidazole and AIEgen for synthesizing efficient electroluminescent materials for OLED devices. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Validation of BlueSky Smoke Prediction System using surface and satellite observations during major wildland fire events in Northern California

Treesearch

Lesley Fusina; Sharon Zhong; Julide Koracin; Tim Brown; Annie Esperanza; Leland Tarney; Haiganoush Preisler

2007-01-01

The BlueSky Smoke Prediction System developed by the U.S. Department of Agriculture, Forest Service, AirFire Team under the National Fire Plan is a modeling framework that integrates tools, knowledge of fuels, moisture, combustion, emissions, plume dynamics, and weather to produce real-time predictions of the cumulative impacts of smoke from wildfires, prescribed fires...

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.

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

Sky-blue emitting bridged diiridium complexes: beneficial effects of intramolecular π-π stacking.

PubMed

Congrave, Daniel G; Hsu, Yu-Ting; Batsanov, Andrei S; Beeby, Andrew; Bryce, Martin R

2018-02-06

The potential of intramolecular π-π interactions to influence the photophysical properties of diiridium complexes is an unexplored topic, and provides the motivation for the present study. A series of diarylhydrazide-bridged diiridium complexes functionalised with phenylpyridine (ppy)-based cyclometalating ligands is reported. It is shown by NMR studies in solution and single crystal X-ray analysis that intramolecular π-π interactions between the bridging and cyclometalating ligands rigidify the complexes leading to high luminescence quantum efficiencies in solution and in doped films. Fluorine substituents on the phenyl rings of the bridge promote the intramolecular π-π interactions. Notably, these non-covalent interactions are harnessed in the rational design and synthesis of the first examples of highly emissive sky-blue diiridium complexes featuring conjugated bridging ligands, for which they play a vital role in the structural and photophysical properties. Experimental results are supported by computational studies.

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

Non-cardinal color perception across the retina: easy for orange, hard for burgundy and sky blue.

PubMed

Gunther, Karen L

2014-04-01

Cardinal color performance (reddish, greenish, bluish, yellowish, black, and white) has been shown to decline in peripheral viewing. What about non-cardinal color performance (e.g., orange, burgundy, and sky blue)? In visual search, performance on non-cardinal colors matched that of the cardinal colors in the (L-M)/(S-(L+M)) (isoluminant) color plane (Experiment 1, n=10, to 30°; Experiment 2, n=3, to 50°). However, performance in the (L-M)/(L+M) and (S-(L+M))/(L+M) color planes was worse for non-cardinal colors, at all eccentricities, even in the fovea. The implications that these results have for the existence of non-cardinal mechanisms in each color plane are discussed.

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

Polish Terms for "Blue" in the Perspective of Vantage Theory

ERIC Educational Resources Information Center

Stanulewicz, Danuta

2010-01-01

The Polish set of terms for blue includes, inter alia, the following adjectives: "niebieski" "blue", "blekitny" "(sky) blue", "granatowy" "navy blue", "lazurowy" "azure", "modry" "(intense) blue" and "siny" "(grey) violet-blue". The adjective "niebieski" is the basic term; however, it shares some of its functions with "blekitny", which is…

Realizing Highly Efficient Solution-Processed Homojunction-Like Sky-Blue OLEDs by Using Thermally Activated Delayed Fluorescent Emitters Featuring an Aggregation-Induced Emission Property.

PubMed

Wu, Kailong; Wang, Zian; Zhan, Lisi; Zhong, Cheng; Gong, Shaolong; Xie, Guohua; Yang, Chuluo

2018-04-05

Two new blue emitters, i.e., bis-[2-(9,9-dimethyl-9,10-dihydroacridine)-phenyl]-sulfone ( o-ACSO2) and bis-[3-(9,9-dimethyl-9,10-dihydroacridine)-phenyl]-sulfone ( m-ACSO2), with reserved fine thermally activated delayed fluorescent (TADF) nature and simply tuned thermal and optoelectronic properties, were synthesized by isomer engineering. The meta-linking compound, i.e., m-ACSO2, obtains the highest photoluminescence quantum yield with a small singlet-triplet energy gap, a moderate delayed fluorescent lifetime, excellent solubility, and neat film homogeneity. Due to its unique aggregation-induced emission (AIE) character, neat film-based heterojunction-like organic light-emitting diodes (OLEDs) are achievable. By inserting an excitonic inert exciton-blocking layer, the PN heterojunction-like emission accompanied by intefacial exciplex was shifted to a homojunction-like channel mainly from the AIE emitter itself, providing a new tactic to generate efficient blue color from neat films. The solution-processed nondoped sky-blue OLED employing m-ACSO2 as emitter with homojunction-like emission achieved a maximum external quantum efficiency of 17.2%. The design strategies presented herein provide practical methods to construct efficient blue TADF dyes and realize high-performance blue TADF devices.

Singing' the Black and Blues

ERIC Educational Resources Information Center

Fisher, Diane

2004-01-01

It is so obvious that the sky is blue in the daytime and black at night, but it took the smartest humans thousands of years of observation, thought, discussion, conjecture, and analysis to finally come up with answers that make scientific sense as to why the sky is these colors. This article discusses light and the scientific research…

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.

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.

Cyclometalated Iridium(III) Carbene Phosphors for Highly Efficient Blue Organic Light-Emitting Diodes.

PubMed

Chen, Zhao; Wang, Liqi; Su, Sikai; Zheng, Xingyu; Zhu, Nianyong; Ho, Cheuk-Lam; Chen, Shuming; Wong, Wai-Yeung

2017-11-22

Five deep blue carbene-based iridium(III) phosphors were synthesized and characterized. Interestingly, one of them can be fabricated into deep blue, sky blue and white organic light-emitting diodes (OLEDs) through changing the host materials and exciton blocking layers. These deep and sky blue devices exhibit Commission Internationale de l'Éclairage (CIE) coordinates of (0.145, 0.186) and (0.152, 0.277) with external quantum efficiency (EQE) of 15.2% and 9.6%, respectively. The EQE of the deep blue device can be further improved up to 19.0% by choosing a host with suitable energy level of its lowest unoccupied molecular orbital (LUMO).

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

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.

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

Atmospheric ozone and colors of the Antarctic twilight sky.

PubMed

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

2011-10-01

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

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.

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.

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

Scattering of Light by Colloidal Aluminosilicate Particles Produces the Unusual Sky-Blue Color of Río Celeste (Tenorio Volcano Complex, Costa Rica)

PubMed Central

Castellón, Erick; Martínez, María; Madrigal-Carballo, Sergio; Arias, María Laura; Vargas, William E.; Chavarría, Max

2013-01-01

Río Celeste (Sky-Blue River) in Tenorio National Park (Costa Rica), a river that derives from the confluence and mixing of two colorless streams—Río Buenavista (Buenavista River) and Quebrada Agria (Sour Creek)—is renowned in Costa Rica because it presents an atypical intense sky-blue color. Although various explanations have been proposed for this unusual hue of Río Celeste, no exhaustive tests have been undertaken; the reasons hence remain unclear. To understand this color phenomenon, we examined the physico-chemical properties of Río Celeste and of the two streams from which it is derived. Chemical analysis of those streams with ion-exchange chromatography (IC) and inductively coupled plasma atomic emission spectroscopy (ICP-OES) made us discard the hypothesis that the origin of the hue is due to colored chemical species. Our tests revealed that the origin of this coloration phenomenon is physical, due to suspended aluminosilicate particles (with diameters distributed around 566 nm according to a lognormal distribution) that produce Mie scattering. The color originates after mixing of two colorless streams because of the enlargement (by aggregation) of suspended aluminosilicate particles in the Río Buenavista stream due to a decrease of pH on mixing with the acidic Quebrada Agria. We postulate a chemical mechanism for this process, supported by experimental evidence of dynamic light scattering (DLS), zeta potential measurements, X-ray diffraction and scanning electron microscopy (SEM) with energy-dispersive spectra (EDS). Theoretical modeling of the Mie scattering yielded a strong coincidence between the observed color and the simulated one. PMID:24058661

Scattering of light by colloidal aluminosilicate particles produces the unusual sky-blue color of Río Celeste (Tenorio volcano complex, Costa Rica).

PubMed

Castellón, Erick; Martínez, María; Madrigal-Carballo, Sergio; Arias, María Laura; Vargas, William E; Chavarría, Max

2013-01-01

Río Celeste (Sky-Blue River) in Tenorio National Park (Costa Rica), a river that derives from the confluence and mixing of two colorless streams--Río Buenavista (Buenavista River) and Quebrada Agria (Sour Creek)--is renowned in Costa Rica because it presents an atypical intense sky-blue color. Although various explanations have been proposed for this unusual hue of Río Celeste, no exhaustive tests have been undertaken; the reasons hence remain unclear. To understand this color phenomenon, we examined the physico-chemical properties of Río Celeste and of the two streams from which it is derived. Chemical analysis of those streams with ion-exchange chromatography (IC) and inductively coupled plasma atomic emission spectroscopy (ICP-OES) made us discard the hypothesis that the origin of the hue is due to colored chemical species. Our tests revealed that the origin of this coloration phenomenon is physical, due to suspended aluminosilicate particles (with diameters distributed around 566 nm according to a lognormal distribution) that produce Mie scattering. The color originates after mixing of two colorless streams because of the enlargement (by aggregation) of suspended aluminosilicate particles in the Río Buenavista stream due to a decrease of pH on mixing with the acidic Quebrada Agria. We postulate a chemical mechanism for this process, supported by experimental evidence of dynamic light scattering (DLS), zeta potential measurements, X-ray diffraction and scanning electron microscopy (SEM) with energy-dispersive spectra (EDS). Theoretical modeling of the Mie scattering yielded a strong coincidence between the observed color and the simulated one.

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%.

What's Up in the Atmosphere? Exploring How Aerosols Impact Sky Color Through Hands-on Activities with Elementary GLOBE

NASA Astrophysics Data System (ADS)

Damadeo, K.; Taylor, J.

2015-12-01

What color is the sky today? The GLOBE Kids - Anita, Simon, and Dennis want to know why the sky isn't always the same shade of blue and sometimes isn't even blue. Through the new Elementary GLOBE Aerosols Storybook and Learning Activities, the GLOBE Kids learn that there's a lot more than air in the atmosphere, which can affect the colors we see in the sky. There are four hands-on activities in this unit: 1) Sky Observers - Students make observations of the sky, record their findings and share their observation reports with their peers. The activity promotes active observation and recording skills to help students observe sky color, and recognize that sky color changes; 2) Why (Not) So Blue? - Students make predictions about how drops of milk will affect color and visibility in cups of water representing the atmosphere to help them understand that aerosols in the atmosphere have an effect on sky conditions, including sky color and visibility. The activity also introduces the classification categories for daytime sky color and visibility; 3) See the Light - Students use prisms and glue sticks to explore the properties of light. The activity demonstrates that white light is made up of seven colors that represent different wavelengths, and illustrates why the sky is blue during the day and red at sunset; 4) Up in the Air - Students work in groups to make an aerosol sampler, a simple adhesive tool that allows students to collect data and estimate the extent of aerosols present at their school, understanding that, in fact, there are particles in the air we breathe. NGSS Alignment includes: Disciplinary Core Ideas- ESS2.D: Weather and Climate, ESS3.C: Human Impacts on Earth Systems, PS4.B: Electromagnetic Radiation, ESS3.A: Natural Resources; Science and Engineering Practices- Asking Questions and Defining Problems, Planning and Carrying Out an Investigation, Analyzing and Interpreting Data, Engaging in Argument from Evidence, Obtaining, Evaluating, and Communicating

Galaxy Morphology Revealed By SDSS: Blue Elliptical Galaxies

NASA Astrophysics Data System (ADS)

Ann, Hong Bae

The Sloan Digital Sky Survey (SDSS) reveals many new features of galaxy morphologies. Among others, the discovery of blue elliptical galaxies provides some insights into the formation and evolution of galaxies. There seems to be two types of blue elliptical galaxies. One type shows globally blue colors suggesting star formations over the entire galaxy whereas the other type shows blue core that indicates enhanced star formation in the nuclear regions. The former seems to be currently forming galaxies, while the latter is thought to be in transition stage from the blue cloud to the red sequence due to AGN feedback.

Enhancement of Near-Real-Time Cloud Analysis and Related Analytic Support for Whole Sky Imagers

DTIC Science & Technology

2007-05-01

Red/ Blue Ratio Through the Sun on 3 Typical Days ................14 Fig. 11 Red/ Blue Ratio Through the Sun on Forward Bias Days ..........15 Fig...12 Red/ Blue Ratio Through the Sun on Reverse Bias Days ...........15 Fig. 13 No Moon Case in Oklahoma...the clear sky red/ blue ratios. Up until this time, we had been using the background from another site and instrument. As part of this contract, we

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

Light Emitting Diodes and Astronomy - a chance for restoration of the dark night sky - or for further loss

NASA Astrophysics Data System (ADS)

Wainscoat, Richard

2015-08-01

Across the planet, conventional light sources such as high pressure sodium, are rapidly being replaced by light emitting diodes (LEDs). As light fixtures are being replaced, there is a tremendous opportunity for restoration of dark night skies through replacement of poorly shielded fixtures by fully shielded fixtures. However, it is critically important to limit the amount of blue light from the LEDs.Sales people are strongly promoting LEDs with high correlated color temperature (CCT), such as 5000K. They are promoting them on energy efficiency grounds - higher energy efficiency is easier to sell. These LEDs have tremendous amounts of blue light near 450 nm. The photopic human eye is relatively insensitive to this blue light, but the dark adapted scotopic eye is much more sensitive, and CCDs are also very sensitive to this wavelength of light. As a consequence, both professional and amateur astronomers are very seriously impacted by high CCT LED lighting. The sodium lighting that the LEDs are replacing has relatively little blue light. Blue light is strongly scattered by air molecules in the atmosphere.Use of high CCT LED lighting will cause further deterioration of night sky quality.In contrast, use of LED lighting with low CCT (e.g., 2400K or 2700K), or use of filters to remove the blue light, can restore the dark night sky. LED lighting is much easier to direct, meaning that an area such as a roadway can be lit with many less lumens with LEDs compared to conventional lights such as high pressure sodium. And use of fully shielded fixtures will eliminate direct uplighting.It is therefore critically important at this time to require that all new LED lighting be fully shielded, and for strong limits to be placed the amount of blue light from LEDs. This is crucial near observatories, but is important everywhere.

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.

The blue skies in Beijing during APEC 2014: A quantitative assessment of emission control efficiency and meteorological influence

NASA Astrophysics Data System (ADS)

Liu, Hongli; He, Jing; Guo, Jianping; Miao, Yucong; Yin, Jinfang; Wang, Yuan; Xu, Hui; Liu, Huan; Yan, Yan; Li, Yuan; Zhai, Panmao

2017-10-01

Most previous studies attributed the alleviation of aerosol pollution to either emission control measures or favorable meteorological conditions. However, our understanding of their quantitative contribution is far from complete. In this study, based on model simulation using the CMA (China Meteorological Administration) Unified Atmospheric Chemistry Environment for aerosols (CUACE/Aero), in combination with simultaneous ground-based hourly PM2.5 observations, we aim to quantify the relative contributions of the emission control measures and meteorology to the blue-skies seen in Beijing during the Asia-Pacific Economic Cooperation (APEC) summit held in November of 2014. A series of model simulations have been performed over Beijing-Tianjin-Hebei (BTH) region by implementing nine different emission control schemes. To investigate the relative contributions of the emission control measures and meteorology, the study period has been divided into five episodes. Overall, the CUACE/Aero model can reasonably well reproduce the temporal and spatial evolution of PM2.5 during APEC 2014, although the model performance varies by different time periods and regions of interest. Model results show the emission control measures on average reduced the PM2.5 concentration by 41.3% in urban areas of Beijing and 39.7% in Huairou district, respectively, indicating emission control plays a significant role for the blue skies observed. Among all the emission control measures under investigation, local emission control in Beijing contributed the largest to the reduction of PM2.5 concentrations with a reduction of 35.5% in urban area of Beijing and 34.8% in Huairou, in contrast with the vehicle emission control in Hebei that contributed the least with a reduction of less than 1%. The emission control efficiency in five episodes has been assessed quantitatively, which falls in the range of 36.2%-41.2% in urban area of Beijing and 34.9%-40.7% in Huairou, indicative of no significant episode

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

Pre-Dawn Martian Sky

NASA Technical Reports Server (NTRS)

1997-01-01

On Sol 39 there were wispy blue clouds in the pre-dawn sky of Mars, as seen by the Imager for Mars Pathfinder (IMP). The color image was made by taking blue, green, and red images and then combining them into a single color image. The clouds appear to have a bluish side and a greenish side because they moved (in the wind from the northeast) between images. This picture was made an hour and twenty minutes before sunrise -- the sun is not shining directly on the water ice clouds, but they are illuminated by the dawn twilight.

Mars Pathfinder is the second in NASA's Discovery program of low-cost spacecraft with highly focused science goals. The Jet Propulsion Laboratory, Pasadena, CA, developed and manages the Mars Pathfinder mission for NASA's Office of Space Science, Washington, D.C. JPL is a division of the California Institute of Technology (Caltech). The Imager for Mars Pathfinder (IMP) was developed by the University of Arizona Lunar and Planetary Laboratory under contract to JPL. Peter Smith is the Principal Investigator.

Supplementing the Digitized Sky Survey for UV-Mission Planning

NASA Technical Reports Server (NTRS)

McLean, Brian

2004-01-01

The Space Telescope Science Institute worked on a project to augment the Digitized Sky Survey archive by completing the scanning and processing of the POSS-I blue survey. This will provide an additional valuable resource to support UV-mission planning. All of the data will be made available through the NASA optical/UV archive (MAST) at STScI. The activities completed during this project are included.

Session 21.1 - Observations, Advances in LED Technology, and Dark Sky Protection

NASA Astrophysics Data System (ADS)

Duriscoe, Dan M.

2016-10-01

The importance of dark sky protection, potential threats to further degradation from LED technology, the announcement of a new world atlas of artificial night sky brightness, and the use of color images from the orbiting International Space Station for monitoring potential sources of light pollution were discussed in the six talks of this session. It was clear from the presentations that the work of professional astronomy depends upon continued restraint in the use of outdoor lighting, especially new LED technology, which relies upon blue-rich sources to support the advantages of high luminous efficacy and resulting energy savings.

A bolt out of the blue.

PubMed

Dwyer, Joseph R

2005-05-01

Lightning is a particularly unsettling product of bad weather. It causes more deaths and injuries in the U.S. than either hurricanes or tornadoes do, and it strikes without warning, sometimes with nothing but blue sky overhead. In central Florida, where I live, thunderstorms are a daily occurrence during the summer, and so, ironically, people in the Sunshine State often spend their afternoons indoors to avoid the risk of death from the sky. Worldwide, lightning flashes about four million times a day, and bolts have even been observed on other planets. Yet despite its familiarity, we still do not know what causes lightning. It is a misconception that Benjamin Franklin solved the puzzle when he conducted his famous kite experiment in 1752.

Hermite scatterers in an ultraviolet sky

NASA Astrophysics Data System (ADS)

Parker, Kevin J.

2017-12-01

The scattering from spherical inhomogeneities has been a major historical topic in acoustics, optics, and electromagnetics and the phenomenon shapes our perception of the world including the blue sky. The long wavelength limit of ;Rayleigh scattering; is characterized by intensity proportional to k4 (or λ-4) where k is the wavenumber and λ is the wavelength. With the advance of nanotechnology, it is possible to produce scatterers that are inhomogeneous with material properties that are functions of radius r, such as concentric shells. We demonstrate that with proper choice of material properties linked to the Hermite polynomials in r, scatterers can have long wavelength scattering behavior of higher powers: k8, k16, and higher. These ;Hermite scatterers; could be useful in providing unique signatures (or colors) to regions where they are present. If suspended in air under white light, the back-scattered spectrum would be shifted from blue towards violet and then ultraviolet as the higher order Hermite scatterers were illuminated.

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.

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.

Efficient Blue Electroluminescence Using Quantum-Confined Two-Dimensional Perovskites.

PubMed

Kumar, Sudhir; Jagielski, Jakub; Yakunin, Sergii; Rice, Peter; Chiu, Yu-Cheng; Wang, Mingchao; Nedelcu, Georgian; Kim, Yeongin; Lin, Shangchao; Santos, Elton J G; Kovalenko, Maksym V; Shih, Chih-Jen

2016-10-03

Solution-processed hybrid organic-inorganic lead halide perovskites are emerging as one of the most promising candidates for low-cost light-emitting diodes (LEDs). However, due to a small exciton binding energy, it is not yet possible to achieve an efficient electroluminescence within the blue wavelength region at room temperature, as is necessary for full-spectrum light sources. Here, we demonstrate efficient blue LEDs based on the colloidal, quantum-confined 2D perovskites, with precisely controlled stacking down to one-unit-cell thickness (n = 1). A variety of low-k organic host compounds are used to disperse the 2D perovskites, effectively creating a matrix of the dielectric quantum wells, which significantly boosts the exciton binding energy by the dielectric confinement effect. Through the Förster resonance energy transfer, the excitons down-convert and recombine radiatively in the 2D perovskites. We report room-temperature pure green (n = 7-10), sky blue (n = 5), pure blue (n = 3), and deep blue (n = 1) electroluminescence, with record-high external quantum efficiencies in the green-to-blue wavelength region.

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.

Celestial polarization patterns sufficient for Viking navigation with the naked eye: detectability of Haidinger's brushes on the sky versus meteorological conditions

NASA Astrophysics Data System (ADS)

Horváth, Gábor; Takács, Péter; Kretzer, Balázs; Szilasi, Szilvia; Száz, Dénes; Farkas, Alexandra; Barta, András

2017-02-01

If a human looks at the clear blue sky from which light with high enough degree of polarization d originates, an 8-shaped bowtie-like figure, the yellow Haidinger's brush can be perceived, the long axis of which points towards the sun. A band of high d arcs across the sky at 90° from the sun. A person can pick two points on that band, observe the yellow brushes and triangulate the position of the sun based on the orientation of the two observed brushes. This method has been suggested to have been used on the open sea by Viking navigators to determine the position of the invisible sun occluded by cloud or fog. Furthermore, Haidinger's brushes can also be used to locate the sun when it is below the horizon or occluded by objects on the horizon. To determine the position of the sun using the celestial polarization pattern, the d of the portion of the sky used must be greater than the viewer's degree of polarization threshold d* for perception of Haidinger's brushes. We studied under which sky conditions the prerequisite d > d* is satisfied. Using full-sky imaging polarimetry, we measured the d-pattern of skylight in the blue (450 nm) spectral range for 1296 different meteorological conditions with different solar elevation angles θ and per cent cloud cover ρ. From the measured d-patterns of a given sky we determined the proportion P of the sky for which d > d*. We obtained that P is the largest at low solar elevations θ ≈ 0° and under totally or nearly clear skies with cloud coverage ρ = 0%, when the sun's position is already easily determined. If the sun is below the horizon (-5° ≤ θ < 0°) during twilight, P = 76.17 ± 4.18% for dmin∗=23 % under clear sky conditions. Consequently, the sky-polarimetric Viking navigation based on Haidinger's brushes is most useful after sunset and prior to sunrise, when the sun is not visible and large sky regions are bright, clear and polarized enough for perception of Haidinger's brushes.

Celestial polarization patterns sufficient for Viking navigation with the naked eye: detectability of Haidinger's brushes on the sky versus meteorological conditions

PubMed Central

Takács, Péter; Kretzer, Balázs; Szilasi, Szilvia; Száz, Dénes; Farkas, Alexandra; Barta, András

2017-01-01

If a human looks at the clear blue sky from which light with high enough degree of polarization d originates, an 8-shaped bowtie-like figure, the yellow Haidinger's brush can be perceived, the long axis of which points towards the sun. A band of high d arcs across the sky at 90° from the sun. A person can pick two points on that band, observe the yellow brushes and triangulate the position of the sun based on the orientation of the two observed brushes. This method has been suggested to have been used on the open sea by Viking navigators to determine the position of the invisible sun occluded by cloud or fog. Furthermore, Haidinger's brushes can also be used to locate the sun when it is below the horizon or occluded by objects on the horizon. To determine the position of the sun using the celestial polarization pattern, the d of the portion of the sky used must be greater than the viewer's degree of polarization threshold d* for perception of Haidinger's brushes. We studied under which sky conditions the prerequisite d > d* is satisfied. Using full-sky imaging polarimetry, we measured the d-pattern of skylight in the blue (450 nm) spectral range for 1296 different meteorological conditions with different solar elevation angles θ and per cent cloud cover ρ. From the measured d-patterns of a given sky we determined the proportion P of the sky for which d > d*. We obtained that P is the largest at low solar elevations θ ≈ 0° and under totally or nearly clear skies with cloud coverage ρ = 0%, when the sun's position is already easily determined. If the sun is below the horizon (−5° ≤ θ < 0°) during twilight, P = 76.17 ± 4.18% for dmin∗=23% under clear sky conditions. Consequently, the sky-polarimetric Viking navigation based on Haidinger's brushes is most useful after sunset and prior to sunrise, when the sun is not visible and large sky regions are bright, clear and polarized enough for perception of Haidinger

Celestial polarization patterns sufficient for Viking navigation with the naked eye: detectability of Haidinger's brushes on the sky versus meteorological conditions.

PubMed

Horváth, Gábor; Takács, Péter; Kretzer, Balázs; Szilasi, Szilvia; Száz, Dénes; Farkas, Alexandra; Barta, András

2017-02-01

If a human looks at the clear blue sky from which light with high enough degree of polarization d originates, an 8-shaped bowtie-like figure, the yellow Haidinger's brush can be perceived, the long axis of which points towards the sun. A band of high d arcs across the sky at 90° from the sun. A person can pick two points on that band, observe the yellow brushes and triangulate the position of the sun based on the orientation of the two observed brushes. This method has been suggested to have been used on the open sea by Viking navigators to determine the position of the invisible sun occluded by cloud or fog. Furthermore, Haidinger's brushes can also be used to locate the sun when it is below the horizon or occluded by objects on the horizon. To determine the position of the sun using the celestial polarization pattern, the d of the portion of the sky used must be greater than the viewer's degree of polarization threshold d * for perception of Haidinger's brushes. We studied under which sky conditions the prerequisite d  >  d * is satisfied. Using full-sky imaging polarimetry, we measured the d -pattern of skylight in the blue (450 nm) spectral range for 1296 different meteorological conditions with different solar elevation angles θ and per cent cloud cover ρ . From the measured d -patterns of a given sky we determined the proportion P of the sky for which d  >  d *. We obtained that P is the largest at low solar elevations θ  ≈ 0° and under totally or nearly clear skies with cloud coverage ρ  = 0%, when the sun's position is already easily determined. If the sun is below the horizon (-5° ≤  θ  < 0°) during twilight, P  = 76.17 ± 4.18% for [Formula: see text] under clear sky conditions. Consequently, the sky-polarimetric Viking navigation based on Haidinger's brushes is most useful after sunset and prior to sunrise, when the sun is not visible and large sky regions are bright, clear and polarized enough for

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.

High-brightness blue organic light emitting diodes with different types of guest-host systems

NASA Astrophysics Data System (ADS)

Wang, Xiao; Zhang, Jing-shuang; Peng, Cui-yun; Guo, Kun-ping; Wei, Bin; Zhang, Hao

2016-03-01

We demonstrate high-brightness blue organic light emitting diodes (OLEDs) using two types of guest-host systems. A series of blue OLEDs were fabricated using three organic emitters of dibenz anthracene (perylene), di(4-fluorophenyl) amino-di (styryl) biphenyl (DSB) and 4,4'-bis[2-(9-ethyl-3-carbazolyl)vinyl]biphenyl (BCzVBi) doped into two hosting materials of 4,4'-bis(9-carbazolyl) biphenyl (CBP) and 2-(4-biphenylyl)-5(4-tert-butyl-phenyl)-1,3,4-oxadiazole (PBD) as blue emitting layers, respectively. We achieve three kinds of devices with colors of deep-blue, pure-blue and sky-blue with the Commission Internationale de L'Eclairage (CIE) coordinates of (0.16, 0.10), (0.15, 0.15) and (0.17, 0.24), respectively, by employing PBD as host material. In addition, we present a microcavity device using the PBD guest-host system and achieve high-purity blue devices with narrowed spectrum.

The lizard celestial compass detects linearly polarized light in the blue.

PubMed

Beltrami, Giulia; Parretta, Antonio; Petrucci, Ferruccio; Buttini, Paola; Bertolucci, Cristiano; Foà, Augusto

2012-09-15

The present study first examined whether ruin lizards, Podarcis sicula, are able to orientate using plane-polarized light produced by an LCD screen. Ruin lizards were trained and tested indoors, inside a hexagonal Morris water maze positioned under an LCD screen producing white polarized light with a single E-vector, which provided an axial cue. White polarized light did not include wavelengths in the UV. Lizards orientated correctly either when tested with E-vector parallel to the training axis or after 90 deg rotation of the E-vector direction, thus validating the apparatus. Further experiments examined whether there is a preferential region of the light spectrum to perceive the E-vector direction of polarized light. For this purpose, lizards reaching learning criteria under white polarized light were subdivided into four experimental groups. Each group was tested for orientation under a different spectrum of plane-polarized light (red, green, cyan and blue) with equalized photon flux density. Lizards tested under blue polarized light orientated correctly, whereas lizards tested under red polarized light were completely disoriented. Green polarized light was barely discernible by lizards, and thus insufficient for a correct functioning of their compass. When exposed to cyan polarized light, lizard orientation performances were optimal, indistinguishable from lizards detecting blue polarized light. Overall, the present results demonstrate that perception of linear polarization in the blue is necessary - and sufficient - for a proper functioning of the sky polarization compass of ruin lizards. This may be adaptively important, as detection of polarized light in the blue improves functioning of the polarization compass under cloudy skies, i.e. when the alternative celestial compass based on detection of the sun disk is rendered useless because the sun is obscured by clouds.

Bright, Multi-responsive, Sky-Blue Platinum(II) Phosphors Based on a Tetradentate Chelating Framework.

PubMed

Liu, Lijie; Wang, Xiang; Wang, Nan; Peng, Tai; Wang, Suning

2017-07-24

A new class of highly efficient and stable, blue-phosphorescent Pt II complexes based on a tetradentate chelating framework has been found to exhibit highly sensitive and reversible responses to multiple external stimuli including temperature, pressure, and UV irradiation with distinct phosphorescent color switching-from blue to red or white. Intermolecular excimer formation is the main origin of this intriguing multi-response phenomenon. Highly efficient singlet-oxygen sensitization by the Pt II compounds yields UV-light-induced phosphorescence enhancement and color switching. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

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!

Low-energy light bulbs, computers, tablets and the blue light hazard.

PubMed

O'Hagan, J B; Khazova, M; Price, L L A

2016-02-01

The introduction of low energy lighting and the widespread use of computer and mobile technologies have changed the exposure of human eyes to light. Occasional claims that the light sources with emissions containing blue light may cause eye damage raise concerns in the media. The aim of the study was to determine if it was appropriate to issue advice on the public health concerns. A number of sources were assessed and the exposure conditions were compared with international exposure limits, and the exposure likely to be received from staring at a blue sky. None of the sources assessed approached the exposure limits, even for extended viewing times.

Low-energy light bulbs, computers, tablets and the blue light hazard

PubMed Central

O'Hagan, J B; Khazova, M; Price, L L A

2016-01-01

The introduction of low energy lighting and the widespread use of computer and mobile technologies have changed the exposure of human eyes to light. Occasional claims that the light sources with emissions containing blue light may cause eye damage raise concerns in the media. The aim of the study was to determine if it was appropriate to issue advice on the public health concerns. A number of sources were assessed and the exposure conditions were compared with international exposure limits, and the exposure likely to be received from staring at a blue sky. None of the sources assessed approached the exposure limits, even for extended viewing times. PMID:26768920

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.

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.

The color of the Martian sky and its influence on the illumination of the Martian surface

USGS Publications Warehouse

Thomas, N.; Markiewicz, W.J.; Sablotny, R.M.; Wuttke, M.W.; Keller, H.U.; Johnson, J. R.; Reid, R.J.; Smith, R.H.

1999-01-01

The dust in the atmosphere above the Mars Pathfinder landing site produced a bright, red sky that increases in redness toward the horizon at midday. There is also evidence for an absorption band in the scattered light from the sky at 860 nm. A model of the sky brightness has been developed [Markiewicz et al., this issue] and tested against Imager for Mars Pathfinder (IMP) observations of calibration targets on the lander. The resulting model has been used to quantify the total diffuse flux onto a surface parallel to the local level for several solar elevation angles and optical depths. The model shows that the diffuse illumination in shadowed areas is strongly reddened while areas illuminated directly by the Sun (and the blue forward scattering peak) see a more solar-type spectrum, in agreement with Viking and IMP observations. Quantitative corrections for the reddening in shadowed areas are demonstrated. It is shown quantitatively that the unusual appearance of the rock Yogi (the east face of which appeared relatively blue in images taken during the morning but relatively red during the afternoon) can be explained purely by the changing illumination geometry. We conclude that any spectrophotometric analysis of surfaces on Mars must take into account the diffuse flux. Specifically, the reflectances of surfaces viewed under different illumination geometries cannot be investigated for spectral diversity unless a correction has been applied which removes the influence of the reddened diffuse flux. Copyright 1999 by the American Geophysical Union.

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/.

CENSUS OF BLUE STARS IN SDSS DR8

DOE PAGES

Scibelli, Samantha; Newberg, Heidi Jo; Carlin, Jeffrey L.; ...

2014-12-02

In this work, we present a census of the 12,060 spectra of blue objects (more » $$(g-r)_0<-0.25$$) in the Sloan Digital Sky Survey (SDSS) Data Release 8 (DR8). As part of the data release, all of the spectra were cross-correlated with 48 template spectra of stars, galaxies and QSOs to determine the best match. We compared the blue spectra by eye to the templates assigned in SDSS DR8. 10,856 of the objects matched their assigned template, 170 could not be classified due to low signal-to-noise (S/N), and 1034 were given new classifications. We identify 7458 DA white dwarfs, 1145 DB white dwarfs, 273 rarer white dwarfs (including carbon, DZ, DQ, and magnetic), 294 subdwarf O stars, 648 subdwarf B stars, 679 blue horizontal branch stars, 1026 blue stragglers, 13 cataclysmic variables, 129 white dwarf - M dwarf binaries, 36 objects with spectra similar to DO white dwarfs, 179 QSOs, and 10 galaxies. We provide two tables of these objects, sample spectra that match the templates, figures showing all of the spectra that were grouped by eye, and diagnostic plots that show the positions, colors, apparent magnitudes, proper motions, etc. for each classification. In conclusion, future surveys will be able to use templates similar to stars in each of the classes we identify to classify blue stars, including rare types, automatically.« less

Cool White Dwarfs Found in the UKIRT Infrared Deep Sky Survey

NASA Astrophysics Data System (ADS)

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

2011-07-01

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

2018's 2nd Blue Moon on March 31 | Astronomy Essentials | EarthSky

Science.gov Websites

Contact Us subscribe Search for: SEARCH Search search Tonight Brightest Stars Astronomy Essentials Moon subscribers and counting ... 2018's 2nd Blue Moon on March 31 By Bruce McClure and Deborah Byrd in Astronomy stacks of the Peridier Library at the University of Texas Astronomy Department in the late 1970s

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.

Identifying the optical phenomena responsible for the blue appearance of veins

NASA Astrophysics Data System (ADS)

Van Leeuwen, Spencer R.; Baranoski, Gladimir V. G.

2017-09-01

Blue in nature is often associated with beauty. It can be observed all around us, from captivating blue eyes to iridescent blue butterfly wings. While colours in nature are often the result of pigmentation, the majority of natural blue is produced by structural coloration. The colour of the sky, for example, is primarily caused by Rayleigh scattering. In this paper, we examine a single occurrence of blue in nature, specifically the blue appearance of veins near the surface of human skin. The most comprehensive investigation of this coloration to date showed that it arises from a combination of the scattering properties of skin and the absorptance of venous blood. However, that work only considered broad optical properties of these mediums and did not identify the source of the colour. In this paper, we employ in silico experiments, performed using first-principles light interaction models for skin and blood, to investigate the net effect of skin and vein optical properties on their aggregate reflectance across the visible range. We show that the contribution of skin to the distinct appearance of veins primarily results from Rayleigh scattering occurring within the papillary dermis, a sublayer of the skin. The results of this paper, in addition to addressing an old open scientific question, may have practical implications for performing non-invasive measurements of the physiological properties of skin and blood.

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

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)…

A Novel Contrast Stain for the Rapid Diagnosis of Pityriasis Versicolor: A Comparison of Chicago Sky Blue 6B Stain, Potassium Hydroxide Mount and Culture.

PubMed

Lodha, Nikita; Poojary, Shital Amin

2015-01-01

The mycological study of pityriasis versicolor is usually done by potassium hydroxide (KOH) mount and culture. However, KOH mount lacks a color contrast and requires a trained eye to interpret, while culture is difficult to perform, time consuming and has low sensitivity. Chicago Sky Blue 6B (CSB) is a new contrast stain that highlights the fungal hyphae and spores, blue against a purplish background. This study was done to compare the utility of a novel contrast stain (CSB stain) with KOH mount and culture. Skin scrapings from the lesions of 100 clinically diagnosed cases of P. versicolor were subjected to (1) KOH mount and CSB stain for direct microscopic examination and (2) culture using Sabouraud's dextrose agar. The statistical analysis of CSB stain and culture was done using KOH mount as the reference method, as it is the most commonly performed and practical diagnostic test available for P. versicolor. An interrater reliability analysis using the Cohen's Kappa statistic was performed to determine consistency (agreement) among the different modalities. Direct microscopy with CSB stain, KOH mount and mycological culture showed positive results in 98 (98%), 92 (92%) and 56 (56%) patients, respectively. Using KOH mount as the reference method, CSB stain had a sensitivity of 100% which was significantly higher than culture (60.9%). Statistically significant fair agreement was found between CSB stain and KOH mount (94% with κ=0.38, P < 0.001). Negligible agreement was found between CSB stain and culture (66%, κ=0.199, P = 0.001) as well as between KOH mount and culture (64%, κ=0.051, P = 0.107). CSB staining of skin scrapings is the most sensitive method for the diagnosis of pityriasis versicolor. Due to the distinct contrast provided by CSB, it is easy to perform, rapid and qualitatively superior to KOH mount.

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.

Application of simple all-sky imagers for the estimation of aerosol optical depth

NASA Astrophysics Data System (ADS)

Kazantzidis, Andreas; Tzoumanikas, Panagiotis; Nikitidou, Efterpi; Salamalikis, Vasileios; Wilbert, Stefan; Prahl, Christoph

2017-06-01

Aerosol optical depth is a key atmospheric constituent for direct normal irradiance calculations at concentrating solar power plants. However, aerosol optical depth is typically not measured at the solar plants for financial reasons. With the recent introduction of all-sky imagers for the nowcasting of direct normal irradiance at the plants a new instrument is available which can be used for the determination of aerosol optical depth at different wavelengths. In this study, we are based on Red, Green and Blue intensities/radiances and calculations of the saturated area around the Sun, both derived from all-sky images taken with a low-cost surveillance camera at the Plataforma Solar de Almeria, Spain. The aerosol optical depth at 440, 500 and 675nm is calculated. The results are compared with collocated aerosol optical measurements and the mean/median difference and standard deviation are less than 0.01 and 0.03 respectively at all wavelengths.

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.

All sky imaging observations in visible and infrared waveband for validation of satellite cloud and aerosol products

NASA Astrophysics Data System (ADS)

Lu, Daren; Huo, Juan; Zhang, W.; Liu, J.

A series of satellite sensors in visible and infrared wavelengths have been successfully operated on board a number of research satellites, e.g. NOAA/AVHRR, the MODIS onboard Terra and Aqua, etc. A number of cloud and aerosol products are produced and released in recent years. However, the validation of the product quality and accuracy are still a challenge to the atmospheric remote sensing community. In this paper, we suggest a ground based validation scheme for satellite-derived cloud and aerosol products by using combined visible and thermal infrared all sky imaging observations as well as surface meteorological observations. In the scheme, a visible digital camera with a fish-eye lens is used to continuously monitor the all sky with the view angle greater than 180 deg. The digital camera system is calibrated for both its geometry and radiance (broad blue, green, and red band) so as to a retrieval method can be used to detect the clear and cloudy sky spatial distribution and their temporal variations. A calibrated scanning thermal infrared thermometer is used to monitor the all sky brightness temperature distribution. An algorithm is developed to detect the clear and cloudy sky as well as cloud base height by using sky brightness distribution and surface temperature and humidity as input. Based on these composite retrieval of clear and cloudy sky distribution, it can be used to validate the satellite retrievals in the sense of real-simultaneous comparison and statistics, respectively. What will be presented in this talk include the results of the field observations and comparisons completed in Beijing (40 deg N, 116.5 deg E) in year 2003 and 2004. This work is supported by NSFC grant No. 4002700, and MOST grant No 2001CCA02200

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.

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

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.

Gram Scale Synthesis of Benzophenanthroline and Its Blue Phosphorescent Platinum Complex

DOE PAGES

Saris, Patrick J. G.; Thompson, Mark E.

2016-08-04

Here, the design, synthesis, and characterization of 12-phenylbenzo[f][1,7]phenanthroline, Bzp, is reported. Its use as a fluorine free ligand for sky blue phosphorescence is demonstrated in a cyclometallated platinum complex, BzpPtDpm. BzpPtDpm phosphoresces at the same wavelength as its analogous 4,6-difluorophenylpyridine complex at both room temperature (466 nm) and 77 kelvin (458 nm). Finally, production of a conformationally restricted derivative of BzpPtDpm with greatly increased quantum yield (46%) validates the versatility of the synthetic route.

Gram Scale Synthesis of Benzophenanthroline and Its Blue Phosphorescent Platinum Complex

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

Saris, Patrick J. G.; Thompson, Mark E.

Here, the design, synthesis, and characterization of 12-phenylbenzo[f][1,7]phenanthroline, Bzp, is reported. Its use as a fluorine free ligand for sky blue phosphorescence is demonstrated in a cyclometallated platinum complex, BzpPtDpm. BzpPtDpm phosphoresces at the same wavelength as its analogous 4,6-difluorophenylpyridine complex at both room temperature (466 nm) and 77 kelvin (458 nm). Finally, production of a conformationally restricted derivative of BzpPtDpm with greatly increased quantum yield (46%) validates the versatility of the synthetic route.

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

Controlling Synergistic Oxidation Processes for Efficient and Stable Blue Thermally Activated Delayed Fluorescence Devices.

PubMed

Cui, Lin-Song; Deng, Ya-Li; Tsang, Daniel Ping-Kuen; Jiang, Zuo-Quan; Zhang, Qisheng; Liao, Liang-Sheng; Adachi, Chihaya

2016-09-01

Efficient sky-blue organic light-emitting diodes (OLEDs) employing thermally activated delayed fluorescence (TADF) display a three orders of magnitude increase in lifetime, which is superior to those of controlled phosphorescent OLEDs used in this study. The combination of electro-oxidation and photo-oxidation of the TADF emitters in their triplet excited-states is suppressed through molecule design and device engineering. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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…

A Novel Contrast Stain for the Rapid Diagnosis of Pityriasis Versicolor: A Comparison of Chicago Sky Blue 6B Stain, Potassium Hydroxide Mount and Culture

PubMed Central

Lodha, Nikita; Poojary, Shital Amin

2015-01-01

Background: The mycological study of pityriasis versicolor is usually done by potassium hydroxide (KOH) mount and culture. However, KOH mount lacks a color contrast and requires a trained eye to interpret, while culture is difficult to perform, time consuming and has low sensitivity. Chicago Sky Blue 6B (CSB) is a new contrast stain that highlights the fungal hyphae and spores, blue against a purplish background. Aims and Objectives: This study was done to compare the utility of a novel contrast stain (CSB stain) with KOH mount and culture. Materials and Methods: Skin scrapings from the lesions of 100 clinically diagnosed cases of P. versicolor were subjected to (1) KOH mount and CSB stain for direct microscopic examination and (2) culture using Sabouraud's dextrose agar. The statistical analysis of CSB stain and culture was done using KOH mount as the reference method, as it is the most commonly performed and practical diagnostic test available for P. versicolor. An interrater reliability analysis using the Cohen's Kappa statistic was performed to determine consistency (agreement) among the different modalities. Observations and Results: Direct microscopy with CSB stain, KOH mount and mycological culture showed positive results in 98 (98%), 92 (92%) and 56 (56%) patients, respectively. Using KOH mount as the reference method, CSB stain had a sensitivity of 100% which was significantly higher than culture (60.9%). Statistically significant fair agreement was found between CSB stain and KOH mount (94% with κ=0.38, P < 0.001). Negligible agreement was found between CSB stain and culture (66%, κ=0.199, P = 0.001) as well as between KOH mount and culture (64%, κ=0.051, P = 0.107). Conclusion: CSB staining of skin scrapings is the most sensitive method for the diagnosis of pityriasis versicolor. Due to the distinct contrast provided by CSB, it is easy to perform, rapid and qualitatively superior to KOH mount. PMID:26288400

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.

Discovery of a new blue quasar: SDSS J022218.03-062511.1

DOE PAGES

Fix, Mees B.; Smith, J. Allyn; Tucker, Douglas L.; ...

2015-07-29

We report the discovery of a bright blue quasar: SDSS J022218.03–062511.1. This object was discovered spectroscopically while searching for hot white dwarfs that may be used as calibration sources for large sky surveys such as the Dark Energy Survey or the Large Synoptic Survey Telescope project. In addition, we present the calibrated spectrum, spectral line shifts and report a redshift of z = 0.521 ± 0.0015 and a rest-frame g-band luminosity of 8.71 × 10 11 L ⊙.

Coupling sky images with radiative transfer models: a new method to estimate cloud optical depth

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

Mejia, Felipe A.; Kurtz, Ben; Murray, Keenan

A method for retrieving cloud optical depth ( τ c) using a UCSD developed ground-based sky imager (USI) is presented. The radiance red–blue ratio (RRBR) method is motivated from the analysis of simulated images of various τ c produced by a radiative transfer model (RTM). From these images the basic parameters affecting the radiance and red–blue ratio (RBR) of a pixel are identified as the solar zenith angle ( θ 0), τ c, solar pixel angle/scattering angle ( θ s), and pixel zenith angle/view angle ( θ z). The effects of these parameters are described and the functions for radiance,more » I λ τ c, θ 0, θ s, θ z , and RBR τ c, θ 0, θ s, θ z are retrieved from the RTM results. RBR, which is commonly used for cloud detection in sky images, provides non-unique solutions for τ c, where RBR increases with τ c up to about τ c = 1 (depending on other parameters) and then decreases. Therefore, the RRBR algorithm uses the measured I λ meas θ s, θ z , in addition to RBR meas θ s, θ z , to obtain a unique solution for τ c. The RRBR method is applied to images of liquid water clouds taken by a USI at the Oklahoma Atmospheric Radiation Measurement (ARM) program site over the course of 220 days and compared against measurements from a microwave radiometer (MWR) and output from the Min et al. (2003) method for overcast skies. τ c values ranged from 0 to 80 with values over 80, being capped and registered as 80. A τ c RMSE of 2.5 between the Min et al. (2003) method and the USI are observed. The MWR and USI  have an RMSE of 2.2, which is well within the uncertainty of the MWR. In conclusion, the procedure developed here provides a foundation to test and develop other cloud detection algorithms.« less

Coupling sky images with radiative transfer models: a new method to estimate cloud optical depth

DOE PAGES

Mejia, Felipe A.; Kurtz, Ben; Murray, Keenan; ...

2016-08-30

A method for retrieving cloud optical depth ( τ c) using a UCSD developed ground-based sky imager (USI) is presented. The radiance red–blue ratio (RRBR) method is motivated from the analysis of simulated images of various τ c produced by a radiative transfer model (RTM). From these images the basic parameters affecting the radiance and red–blue ratio (RBR) of a pixel are identified as the solar zenith angle ( θ 0), τ c, solar pixel angle/scattering angle ( θ s), and pixel zenith angle/view angle ( θ z). The effects of these parameters are described and the functions for radiance,more » I λ τ c, θ 0, θ s, θ z , and RBR τ c, θ 0, θ s, θ z are retrieved from the RTM results. RBR, which is commonly used for cloud detection in sky images, provides non-unique solutions for τ c, where RBR increases with τ c up to about τ c = 1 (depending on other parameters) and then decreases. Therefore, the RRBR algorithm uses the measured I λ meas θ s, θ z , in addition to RBR meas θ s, θ z , to obtain a unique solution for τ c. The RRBR method is applied to images of liquid water clouds taken by a USI at the Oklahoma Atmospheric Radiation Measurement (ARM) program site over the course of 220 days and compared against measurements from a microwave radiometer (MWR) and output from the Min et al. (2003) method for overcast skies. τ c values ranged from 0 to 80 with values over 80, being capped and registered as 80. A τ c RMSE of 2.5 between the Min et al. (2003) method and the USI are observed. The MWR and USI  have an RMSE of 2.2, which is well within the uncertainty of the MWR. In conclusion, the procedure developed here provides a foundation to test and develop other cloud detection algorithms.« less

Polarization transition between sunlit and moonlit skies with possible implications for animal orientation and Viking navigation: anomalous celestial twilight polarization at partial moon.

PubMed

Barta, András; Farkas, Alexandra; Száz, Dénes; Egri, Ádám; Barta, Pál; Kovács, József; Csák, Balázs; Jankovics, István; Szabó, Gyula; Horváth, Gábor

2014-08-10

Using full-sky imaging polarimetry, we measured the celestial distribution of polarization during sunset and sunrise at partial (78% and 72%) and full (100%) moon in the red (650 nm), green (550 nm), and blue (450 nm) parts of the spectrum. We investigated the temporal change of the patterns of degree p and angle α of linear polarization of sunlit and moonlit skies at dusk and dawn. We describe here the position change of the neutral points of sky polarization, and present video clips about the celestial polarization transition at moonlit twilight. We found that at partial moon and at a medium latitude (47° 15.481' N) during this transition there is a relatively short (10-20 min) period when (i) the maximum of p of skylight decreases, and (ii) from the celestial α pattern neither the solar-antisolar nor the lunar-antilunar meridian can be unambiguously determined. These meridians can serve as reference directions of animal orientation and Viking navigation based on sky polarization. The possible influence of these atmospheric optical phenomena during the polarization transition between sunlit and moonlit skies on the orientation of polarization-sensitive crepuscular/nocturnal animals and the hypothesized navigation of sunstone-aided Viking seafarers is discussed.

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.

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 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.

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.

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

NASA Astrophysics Data System (ADS)

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

2001-10-01

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

The SkyMapper Transient Survey

NASA Astrophysics Data System (ADS)

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

2017-07-01

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

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.

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.

How well does the Rayleigh model describe the E-vector distribution of skylight in clear and cloudy conditions? A full-sky polarimetric study.

PubMed

Suhai, Bence; Horváth, Gábor

2004-09-01

We present the first high-resolution maps of Rayleigh behavior in clear and cloudy sky conditions measured by full-sky imaging polarimetry at the wavelengths of 650 nm (red), 550 nm (green), and 450 nm (blue) versus the solar elevation angle thetas. Our maps display those celestial areas at which the deviation deltaalpha = /alphameas - alphaRyleigh/ is below the threshold alphathres = 5 degrees, where alphameas is the angle of polarization of skylight measured by full-sky imaging polarimetry, and alphaRayleigh is the celestial angle of polarization calculated on the basis of the single-scattering Rayleigh model. From these maps we derived the proportion r of the full sky for which the single-scattering Rayleigh model describes well (with an accuracy of deltaalpha = 5 degrees) the E-vector alignment of skylight. Depending on thetas, r is high for clear skies, especially for low solar elevations (40% < r < 70% for thetas < or = 13 degrees). Depending on the cloud cover and the solar illumination, r decreases more or less under cloudy conditions, but sometimes its value remains remarkably high, especially at low solar elevations (rmax = 69% for thetas = 0 degrees). The proportion r of the sky that follows the Rayleigh model is usually higher for shorter wavelengths under clear as well as cloudy sky conditions. This partly explains why the shorter wavelengths are generally preferred by animals navigating by means of the celestial polarization. We found that the celestial E-vector pattern generally follows the Rayleigh pattern well, which is a fundamental hypothesis in the studies of animal orientation and human navigation (e.g., in aircraft flying near the geomagnetic poles and using a polarization sky compass) with the use of the celestial alpha pattern.

VizieR Online Data Catalog: South Galactic cap MCT blue objects (Lamontagne+, 2000)

NASA Astrophysics Data System (ADS)

Lamontagne, R.; Demers, S.; Wesemael, F.; Fontaine, G.; Irwin, M. J.

2016-07-01

A detailed description of the first part of our survey, namely, the photographic observations (including plate scanning, photometric calibrations, and candidate selection), has been presented by Demers et al. (1986AJ.....92..878D). Briefly summarized, the MCT survey consists of 430 doubly exposed U and B plates, taken with the Curtis Schmidt telescope at the Cerro Tololo Inter-American Observatory (CTIO) and covering 6750 deg2 (~15% of the whole sky) in a region defined by 19h<~RA<~7h and -90°<=DE<=0°. Our survey blankets most of the south Galactic cap of our Galaxy accessible from CTIO, up to b=-30°. The bulk of our spectroscopic material was gathered at CTIO with the 1.5m and 4m telescopes in the course of several observing runs since 1985. We have identified all 228 selected blue candidates [(U-B)pg<=-0.6] brighter than Bpg=16.5 in this region of the sky. (1 data file).

Cloud cover detection combining high dynamic range sky images and ceilometer measurements

NASA Astrophysics Data System (ADS)

Román, R.; Cazorla, A.; Toledano, C.; Olmo, F. J.; Cachorro, V. E.; de Frutos, A.; Alados-Arboledas, L.

2017-11-01

This paper presents a new algorithm for cloud detection based on high dynamic range images from a sky camera and ceilometer measurements. The algorithm is also able to detect the obstruction of the sun. This algorithm, called CPC (Camera Plus Ceilometer), is based on the assumption that under cloud-free conditions the sky field must show symmetry. The symmetry criteria are applied depending on ceilometer measurements of the cloud base height. CPC algorithm is applied in two Spanish locations (Granada and Valladolid). The performance of CPC retrieving the sun conditions (obstructed or unobstructed) is analyzed in detail using as reference pyranometer measurements at Granada. CPC retrievals are in agreement with those derived from the reference pyranometer in 85% of the cases (it seems that this agreement does not depend on aerosol size or optical depth). The agreement percentage goes down to only 48% when another algorithm, based on Red-Blue Ratio (RBR), is applied to the sky camera images. The retrieved cloud cover at Granada and Valladolid is compared with that registered by trained meteorological observers. CPC cloud cover is in agreement with the reference showing a slight overestimation and a mean absolute error around 1 okta. A major advantage of the CPC algorithm with respect to the RBR method is that the determined cloud cover is independent of aerosol properties. The RBR algorithm overestimates cloud cover for coarse aerosols and high loads. Cloud cover obtained only from ceilometer shows similar results than CPC algorithm; but the horizontal distribution cannot be obtained. In addition, it has been observed that under quick and strong changes on cloud cover ceilometers retrieve a cloud cover fitting worse with the real cloud cover.

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.

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.

Particle Physics in the Sky and Astrophysics Underground: Connecting the Universe's Largest and Smallest Scales

NASA Astrophysics Data System (ADS)

Swanson, Molly E. C.

2008-08-01

Particles have tremendous potential as astronomical messengers, and conversely, studying the universe as a whole also teaches us about particle physics. This thesis encompasses both of these research directions. Many models predict a diffuse flux of high energy neutrinos from active galactic nuclei and other astrophysical sources. The "Astrophysics Underground" portion of this thesis describes a search for this neutrino flux performed by looking for very high energy upward-going muons using the Super-K detector. In addition to using particles to do astronomy, we can also use the universe itself as a particle physics lab. The "Particle Physics in the Sky" portion of this thesis focuses on extracting cosmological information from galaxy surveys. To overcome technical challenges faced by the latest galaxy surveys, we produced a comprehensive upgrade to mangle, a software package that processes the angular masks defining the survey area on the sky. We added dramatically faster algorithms and new useful features that are necessary for managing complex masks of current and next-generation galaxy surveys. With this software in hand, we utilized SDSS data to investigate the relation between galaxies and dark matter by studying relative bias, i.e., the relation between different types of galaxies. Separating galaxies by their luminosities and colors reveals a complicated picture: red galaxies are clustered more strongly than blue galaxies, with both the brightest and the faintest red galaxies showing the strongest clustering. Furthermore, red and blue galaxies tend to occupy different regions of space. In order to make precise measurements from the next generation of galaxy surveys, it will be essential to account for this complexity.

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.

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…

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.

VizieR Online Data Catalog: Census of blue stars in SDSS DR8 (Scibelli+, 2014)

NASA Astrophysics Data System (ADS)

Scibelli, S.; Newberg, H. J.; Carlin, J. L.; Yanny, B.

2015-02-01

We present a census of the 12060 spectra of blue objects ((g-r)0<-0.25) in the Sloan Digital Sky Survey (SDSS) Data Release 8 (DR8). As part of the data release, all of the spectra were cross-correlated with 48 template spectra of stars, galaxies, and QSOs to determine the best match. We compared the blue spectra by eye to the templates assigned in SDSS DR8. 10856 of the objects matched their assigned template, 170 could not be classified due to low signal-to-noise ratio, and 1034 were given new classifications. We identify 7458 DA white dwarfs, 1145 DB white dwarfs, 273 rarer white dwarfs (including carbon, DZ, DQ, and magnetic), 294 subdwarf O stars, 648 subdwarf B stars, 679 blue horizontal branch stars, 1026 blue stragglers, 13 cataclysmic variables, 129 white dwarf-M dwarf binaries, 36 objects with spectra similar to DO white dwarfs, 179, quasi-stellar objects (QSOs), and 10 galaxies. We provide two tables of these objects, sample spectra that match the templates, figures showing all of the spectra that were grouped by eye, and diagnostic plots that show the positions, colors, apparent magnitudes, proper motions, etc., for each classification. (3 data files).

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.

Correlations among Galaxy Properties from the Sloan Digital Sky Survey

NASA Astrophysics Data System (ADS)

Li, Zhongmu; Mao, Caiyan

2013-07-01

Galaxies are complex systems with many properties. Correlations among galaxy properties can supply important clues for studying the formation and evolution of galaxies. Using principal component analysis and least-squares fitting, this paper investigates the correlations among galactic parameters involving more properties (color, morphology, stellar population, and absolute magnitude) than previous studies. We use a volume-limited sample (whole sample) of 75,423 galaxies that was selected from the Sloan Digital Sky Survey Data Release 2 and divided into two subsamples (blue and red samples) using a critical color of (g - r) = 0.70 mag. In addition to recovering some previous results, we also obtain some new results. First, all separators for dividing galaxies into two groups can be related via good parameter-first principal component (PC1) correlations. A critical PC1 that indicates whether or not stellar age (or the evolution of a stellar population over time) is important can be used to separate galaxies. This suggests that a statistical parameter, PC1, is helpful in understanding the physical separators of galaxies. In addition, stellar age is shown to be unimportant for red galaxies, while both stellar age and mass are dominating parameters of blue galaxies. This suggests that the various numbers of dominating parameters of galaxies may result from the use of different samples. Finally, some parameters are shown to be correlated, and quantitative fits for a few correlations are obtained, e.g., log(t) = 8.57 + 1.65 (g - r) for the age (log t) and color (g - r) of blue galaxies and log (M *) = 4.31 - 0.30 M r for the stellar mass (log M *) and absolute magnitude (M r) of red galaxies. The median relationships between various parameter pairs are also presented for comparison.

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.

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

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

Schlafly, Edward F.; Finkbeiner, Douglas P.

2011-08-20

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

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

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.

Comparative study of efficacy, rapidity of detection, and cost-effectiveness of potassium hydroxide, calcofluor white, and Chicago sky blue stains in the diagnosis of dermatophytoses.

PubMed

Prakash, R; Prashanth, Hosakere Veerappa; Ragunatha, Shivanna; Kapoor, Meenakshi; Anitha, T K; Krishnamurthy, Veena

2016-04-01

The diagnosis of superficial mycosis such as dermatophytosis is often done clinically. However, in difficult cases, a rapid test with high sensitivity and specificity helps in the immediate confirmation and administration of treatment. The efficacy, rapidity of detection, and cost-effectiveness of KOH preparation, calcofluor white (CW) stain, and Chicago sky blue (CSB) stain in the identification of fungal elements were assessed in patients with dermatophytoses attending the dermatology clinic of a tertiary care hospital. All three tests were performed on each sample collected from 73 patients according to standard procedure. The slides were examined after 5 and 30 minutes in × 10 and × 40 magnifications. The sensitivity and specificity of CW and CSB at 5 and 30 minutes were calculated using KOH preparation as the standard test. CSB stain showed highest positivity (94.5%) within 5 minutes when compared to KOH (75.3%) and CW (83.5%). After 30 minutes, positivity increased in KOH (84.9%) and CW stains (89%), but it remained the same in CSB stain. Both CW and CSB stains when compared to 10% KOH are equally sensitive (100%), but CW was more specific (72.7%), particularly at 30 minutes. When cost of performing tests on 100 specimens is considered, KOH, CW, and CSB stains cost Rs 5, 100, and 15, respectively. CSB stain is a better stain for rapid diagnosis of dermatophytoses because of ease of performance, rapidity of detection, better appreciation of morphology of fungal elements, and cost effectiveness. © 2016 The International Society of Dermatology.

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.

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

NASA Astrophysics Data System (ADS)

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

2018-06-01

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

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

A-Train Aerosol Observations Preliminary Comparisons with AeroCom Models and Pathways to Observationally Based All-Sky Estimates

NASA Technical Reports Server (NTRS)

Redemann, J.; Livingston, J.; Shinozuka, Y.; Kacenelenbogen, M.; Russell, P.; LeBlanc, S.; Vaughan, M.; Ferrare, R.; Hostetler, C.; Rogers, R.;

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.

40 CFR 94.8 - Exhaust emission standards.

Code of Federal Regulations, 2010 CFR

2010-07-01

...)(i) of this section. (f) The following define the requirements for low-emitting Blue Sky Series engines: (1) Voluntary standards. (i) Category 1 and Category 2 engines may be designated “Blue Sky Series... may be designated “Blue Sky Series” engines by meeting these voluntary standards that would apply to...

Rapid approach to the quantitative determination of nocturnal ground irradiance in populated territories: a clear-sky case

NASA Astrophysics Data System (ADS)

Kocifaj, Miroslav; Petržala, Jaromír

2016-11-01

A zero-order approach to the solving of the radiative transfer equation and a method for obtaining the horizontal diffuse irradiance at night-time are both developed and intended for wide use in numerical predictions of nocturnal ground irradiance in populated territories. Downward diffuse radiative fluxes are computed with a two-stream approximation, and the data products obtained are useful for scientists who require rapid estimations of illumination levels during the night. The rapid technique presented here is especially important when the entire set of calculations is to be repeated for different lighting technologies and/or radiant intensity distributions with the aim of identifying high-level illuminance/irradiance, the spectral composition of scattered light or other optical properties of diffuse light at the ground level. The model allows for the computation of diffuse horizontal irradiance due to light emissions from ground-based sources with arbitrary spectral compositions. The optical response of a night sky is investigated using the ratio of downward to upward irradiance, R⊥, λ(0). We show that R⊥, λ(0) generally peaks at short wavelengths, thus suggesting that, e.g., the blue light of an LED lamp would make the sky even more bluish. However, this effect can be largely suppressed or even removed with the spectral sensitivity function of the average human eye superimposed on to the lamp spectrum. Basically, blue light scattering dominates at short optical distances, while red light is transmitted for longer distances and illuminates distant places. Computations are performed for unshielded as well as fully shielded lights, while the spectral function R⊥, λ(0) is tabulated to make possible the modelling of various artificial lights, including those not presented here.

Color-magnitude distribution of face-on nearby galaxies in Sloan digital sky survey DR7

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

Jin, Shuo-Wen; Feng, Long-Long; Gu, Qiusheng

2014-05-20

We have analyzed the distributions in the color-magnitude diagram (CMD) of a large sample of face-on galaxies to minimize the effect of dust extinctions on galaxy color. About 300,000 galaxies with log (a/b) < 0.2 and redshift z < 0.2 are selected from the Sloan Digital Sky Survey DR7 catalog. Two methods are employed to investigate the distributions of galaxies in the CMD, including one-dimensional (1D) Gaussian fitting to the distributions in individual magnitude bins and two-dimensional (2D) Gaussian mixture model (GMM) fitting to galaxies as a whole. We find that in the 1D fitting, two Gaussians are not enoughmore » to fit galaxies with the excess present between the blue cloud and the red sequence. The fitting to this excess defines the center of the green valley in the local universe to be (u – r){sub 0.1} = –0.121M {sub r,} 0{sub .1} – 0.061. The fraction of blue cloud and red sequence galaxies turns over around M {sub r,} {sub 0.1} ∼ –20.1 mag, corresponding to stellar mass of 3 × 10{sup 10} M {sub ☉}. For the 2D GMM fitting, a total of four Gaussians are required, one for the blue cloud, one for the red sequence, and the additional two for the green valley. The fact that two Gaussians are needed to describe the distributions of galaxies in the green valley is consistent with some models that argue for two different evolutionary paths from the blue cloud to the red sequence.« less

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.

Ashra (All-sky Survey High Resolution Air-shower detector)Current Status on Mauna Loa, Hawai`i

NASA Astrophysics Data System (ADS)

Hamilton, John; Fox, R. A.; Sasaki, M.; Asaoka, Y.; Ashra Collaboration

2008-09-01

Now in its third year of on-site activities, Ashra is commencing full testing of its array of Cherenkov and Nitrogen Fluorescence detectors. The All-sky Survey High Resolution Air-shower detector is located on the northern upper slopes of Mauna Loa at the 11,000 ft elevation level. Utilizing a clear view of 80% of the sky and an unobstructed view of Mauna Kea, anglular resolution of 1.2 arcmin, sensitive to the blue to UV light with the use of image intensifier and CMOS technology, Ashra is in a unique position for studying the sources of High Energy Cosmic Ray sources (GRB, etc) as well as potential observations of earth-grazing neutrino interactions. 2004 saw the successful deployment of a prototype detector on Haleakala, with confirmed detection of several GRBs. Since the summer of 2005, steady progress was made in constructing and installation of detectors and their weather-proofed housings. UH-Hilo undergraduate students provided summer interns for this international collaboration between ICRR Univ. Tokyo, Univ. Hawai`i-Hilo, Univ Hawai`i-Manoa, Ibaraki Univ., Toho Univ. Chiba Univ., Kanagawa Univ., Nagoya Univ. & Tokyo Institute of Technology.

Blue nevus and "malignant blue nevus:" A concise review.

PubMed

Sugianto, Jessica Zarah; Ralston, Jonathan Scott; Metcalf, John S; McFaddin, Courtney L; Smith, M Timothy

2016-07-01

Blue nevi are a heterogeneous group of lesions that can display a variety of different clinicopathological characteristics. Although attempts are made to classify each lesion into defined subtypes, there can be overlap between the subtypes. The clinical and histolopathologic features of common blue nevi and cellular blue nevi are discussed, as well as blue nevi with atypical features and malignant lesions with features of blue nevi. Copyright © 2016 Elsevier Inc. All rights reserved.

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)

True Color and Chromaticity of the Martian Surface and Sky from Mars Exploration Rover Pancam Observations

NASA Astrophysics Data System (ADS)

Savransky, D.; Bell, J. F.

2004-12-01

We calculate the quantitative color of Mars using calibrated data from the Panoramic Cameras (Pancams) on the Mars Exploration Rovers Spirit and Opportunity. Measured color values allow us to directly compare the color properties of the rover landing sites with the Mars Pathfinder and Viking Lander sites, to quantify systematic changes in color over time, and to increase our perceptual understanding of conditions on the Martian surface. By converting calculated color values to the sRGB color space employed by the majority of modern computer monitors and printers, "true color" representations of the martian surface and sky are produced. Initial colorimetry values are calculated as CIE tristimulus values (the red, green, and blue components of human color vision). Calibrated radiance images from the six discrete left eye Pancam narrow band filters (centered at 753, 673, 601, 535, 482, and 432 nm) are splined to estimate an entire human visible spectrum (360 to 830 nm) for each pixel. Tristimulus values are found by discretely summing over the products of the spectra and 3 CIE color matching functions, allowing chromaticities (normalized tristimulus values) to be calculated. CIE tristimulus values are convolved with a transformation matrix to create sRGB tristimulus values which are then fit to a 2.2 gamma curve and scaled to the range of 0 to 255, 24 bit encoding (8 bits/channel) used by the majority of color displays. An average normalized surface spectrum is used to approximate chromaticities for images with only partial left eye filter sets. Chromaticity values of the martian sky and surface at various points throughout the mission generally match those from the Pathfinder and Viking landing sites. Using the color designation method defined by the ISCC-NBS, the martian sky is "light to moderate yellowish brown," while average rocks and soil vary between "dark grayish yellowish brown" to "moderate brown". Study of changes in the colors of the rover calibration

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.

"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.

The search for Near Earth Objects - why dark skies are critically important

NASA Astrophysics Data System (ADS)

Wainscoat, Richard

2015-08-01

Impact of Earth by asteroids is perhaps the only natural disaster that can be prevented. If an asteroid that will impact Earth can be identified sufficiently early, it is possible to modify its orbit to eliminate the impact. As a consequence, a major effort is presently underway to identify Near Earth Objects (NEOs) that may present a threat to Earth. The impact of a 20-meter diameter object near Chelyabinsk, Russia, provided a spectacular reminder of the threat that these objects present. Although no deaths were caused, injuries and a large amount of property damage were caused.The search for NEOs is mostly funded by NASA. The principal search telescopes are the Pan-STARRS telescopes, located on Haleakala, Maui, Hawaii, and the Catalina Sky Survey, located near Tucson, Arizona. Both of these locations are seriously threatened by light pollution. A new survey, ATLAS, will commence shortly, with one telescope located on Haleakala, Maui, and the other telescope located on Mauna Loa, Hawaii (which is less threatened).Artificial light (i.e., light pollution) at these observing sites raises the sky background, and makes faint objects harder or impossible to see.Searches for Near Earth Objects typically use very broad passbands in order to obtain the maximum amount of light. These passbands typically stretch from 400 to 820 nm. As such, they are very vulnerable to the changes in lighting that are occurring across the globe, with widespread introduction of blue-rich white lighting. It is critically important in all of these locations to limit the amount of blue light that is so readily scattered by the atmosphere.A network of followup telescopes, spread across the planet, play a crucial role in the discovery of NEOs. After a new NEO is identified by the survey telescopes such as Pan-STARRS and Catalina, additional observations must be secured to establish its orbit, and in order to determine whether it poses a threat to Earth. The majority of these followup telescopes are

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.

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.

Two-dimensional Topology of the Sloan Digital Sky Survey

NASA Astrophysics Data System (ADS)

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

2002-12-01

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

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.

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

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.

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.

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.

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

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.

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.

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.

Young Blue Straggler Stars in the Galactic Field

NASA Astrophysics Data System (ADS)

Ekanayake, Gemunu; Wilhelm, Ronald

2018-06-01

In this study we present an analysis of a sample of field blue straggler (BS) stars that show high ultra violet emission in their spectral energy distributions (SED): indication of a hot white dwarf (WD) companion to BS. Using photometry available in the Sloan Digital Sky Survey (SDSS) and Galaxy Evolution Explorer (GALEX ) surveys we identified 80 stars with UV excess. To determine the parameter distributions (mass, temperature and age) of the WD companions, we developed a fitting routine that could fit binary model SEDs to the observed SED. Results from this fit indicate the need for a hot WD companion to provide the excess UV flux. The WD mass distribution peaks at ˜0.4 M⊙, suggesting the primary formation channel of field BSs is case B mass transfer, i.e. when the donor star is in red giant phase of its evolution. Based on stellar evolutionary models, we estimate the lower limit of the binary mass transfer efficiency to be β ˜ 0.5.

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.

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

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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

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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

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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

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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

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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.

Blue Note

ScienceCinema

Murray Gibson

2017-12-09

Argonne's Murray Gibson is a physicist whose life's work includes finding patterns among atoms. The love of distinguishing patterns also drives Gibson as a musician and Blues enthusiast."Blue" notes are very harmonic notes that are missing from the equal temperament scale.The techniques of piano blues and jazz represent the melding of African and Western music into something totally new and exciting.

Blue Note

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

Murray Gibson

2007-04-27

Argonne's Murray Gibson is a physicist whose life's work includes finding patterns among atoms. The love of distinguishing patterns also drives Gibson as a musician and Blues enthusiast."Blue" notes are very harmonic notes that are missing from the equal temperament scale.The techniques of piano blues and jazz represent the melding of African and Western music into something totally new and exciting.

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

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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.

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.

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.

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

Wild Fire Emissions for the NOAA Operational HYSPLIT Smoke Model

NASA Astrophysics Data System (ADS)

Huang, H. C.; ONeill, S. M.; Ruminski, M.; Shafran, P.; McQueen, J.; DiMego, G.; Kondragunta, S.; Gorline, J.; Huang, J. P.; Stunder, B.; Stein, A. F.; Stajner, I.; Upadhayay, S.; Larkin, N. K.

2015-12-01

Particulate Matter (PM) generated from forest fires often lead to degraded visibility and unhealthy air quality in nearby and downstream areas. To provide near-real time PM information to the state and local agencies, the NOAA/National Weather Service (NWS) operational HYSPLIT (Hybrid Single Particle Lagrangian Integrated Trajectory Model) smoke modeling system (NWS/HYSPLIT smoke) provides the forecast of smoke concentration resulting from fire emissions driven by the NWS North American Model 12 km weather predictions. The NWS/HYSPLIT smoke incorporates the U.S. Forest Service BlueSky Smoke Modeling Framework (BlueSky) to provide smoke fire emissions along with the input fire locations from the NOAA National Environmental Satellite, Data, and Information Service (NESDIS)'s Hazard Mapping System fire and smoke detection system. Experienced analysts inspect satellite imagery from multiple sensors onboard geostationary and orbital satellites to identify the location, size and duration of smoke emissions for the model. NWS/HYSPLIT smoke is being updated to use a newer version of USFS BlueSky. The updated BlueSky incorporates the Fuel Characteristic Classification System version 2 (FCCS2) over the continental U.S. and Alaska. FCCS2 includes a more detailed description of fuel loadings with additional plant type categories. The updated BlueSky also utilizes an improved fuel consumption model and fire emission production system. For the period of August 2014 and June 2015, NWS/HYSPLIT smoke simulations show that fire smoke emissions with updated BlueSky are stronger than the current operational BlueSky in the Northwest U.S. For the same comparisons, weaker fire smoke emissions from the updated BlueSky were observed over the middle and eastern part of the U.S. A statistical evaluation of NWS/HYSPLIT smoke predicted total column concentration compared to NOAA NESDIS GOES EAST Aerosol Smoke Product retrievals is underway. Preliminary results show that using the newer version

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

Teaching Astronomy Through Art: Under Southern Skies -- Aboriginal and Western Scientific Perspectives of the Australian Night Sky

NASA Astrophysics Data System (ADS)

Majewski, S. R.; Boles, M. S.; Patterson, R. J.

1999-12-01

We have created an exhibit, Under Southern Skies -- Aboriginal and Western Scientific Perspectives of the Australian Night Sky, which has shown since June, 1999 in newly refurbished exhibit space at the Leander McCormick Observatory. The University of Virginia has a long and continuing tradition of astrometry starting with early parallax work at the McCormick Observatory, extending to our own NSF CAREER Award-funded projects, and including a long-term, ongoing southern parallax program at Mt. Stromlo and Siding Springs Observatories in Australia. Recently, through a gift of Mr. John Kluge, the University of Virginia has obtained one of the most extensive collections of Australian Aboriginal art outside of Australia. The goal of our exhibit is to unite the University's scientific, artistic and cultural connections to Australia through an exhibit focusing on different perspectives of the Australian night sky. We have brought together Australian Aboriginal bark and canvas paintings that feature astronomical themes, e.g., Milky Way, Moon, Magellanic Cloud and Seven Sisters Dreamings, from the Kluge-Ruhe and private collections. These paintings, from the Central Desert and Arnhem Land regions of Australia, are intermingled with modern, large format, color astronomical images of the same scenes. Descriptive panels and a small gallery guide explain the cultural, artistic and scientific aspects of the various thematic groupings based on particular southern hemisphere night sky objects and associated Aboriginal traditions and stories. This unusual combination of art and science not only provides a unique avenue for educating the public about both astronomy and Australian Aboriginal culture, but highlights mankind's ancient and continuing connection to the night sky. We appreciate funding from NSF CAREER Award #AST-9702521, a Cottrell Scholar Award from The Research Corporation, and the Dept. of Astronomy and Ruhe-Kluge Collection at the University of Virginia.

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.

High-luminosity blue and blue-green gallium nitride light-emitting diodes.

PubMed

Morkoç, H; Mohammad, S N

1995-01-06

Compact and efficient sources of blue light for full color display applications and lighting eluded and tantalized researchers for many years. Semiconductor light sources are attractive owing to their reliability and amenability to mass manufacture. However, large band gaps are required to achieve blue color. A class of compound semiconductors formed by metal nitrides, GaN and its allied compounds AIGaN and InGaN, exhibits properties well suited for not only blue and blue-green emitters, but also for ultraviolet emitters and detectors. What thwarted engineers and scientists from fabricating useful devices from these materials in the past was the poor quality of material and lack of p-type doping. Both of these obstacles have recently been overcome to the point where highluminosity blue and blue-green light-emitting diodes are now available in the marketplace.

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.

Efficient Sky-Blue Perovskite Light-Emitting Devices Based on Ethylammonium Bromide Induced Layered Perovskites.

PubMed

Wang, Qi; Ren, Jie; Peng, Xue-Feng; Ji, Xia-Xia; Yang, Xiao-Hui

2017-09-06

Low-dimensional organometallic halide perovskites are actively studied for the light-emitting applications due to their properties such as solution processability, high luminescence quantum yield, large exciton binding energy, and tunable band gap. Introduction of large-group ammonium halides not only serves as a convenient and versatile method to obtain layered perovskites but also allows the exploitation of the energy-funneling process to achieve a high-efficiency light emission. Herein, we investigate the influence of the addition of ethylammonium bromide on the morphology, crystallite structure, and optical properties of the resultant perovskite materials and report that the phase transition from bulk to layered perovskite occurs in the presence of excess ethylammonium bromide. On the basis of this strategy, we report green perovskite light-emitting devices with the maximum external quantum efficiency of ca. 3% and power efficiency of 9.3 lm/W. Notably, blue layered perovskite light-emitting devices with the Commission Internationale de I'Eclairage coordinates of (0.16, 0.23) exhibit the maximum external quantum efficiency of 2.6% and power efficiency of 1 lm/W at 100 cd/m 2 , representing a large improvement over the previously reported analogous devices.

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

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

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.

Blue ocean strategy.

PubMed

Kim, W Chan; Mauborgne, Renée

2004-10-01

Despite a long-term decline in the circus industry, Cirque du Soleil profitably increased revenue 22-fold over the last ten years by reinventing the circus. Rather than competing within the confines of the existing industry or trying to steal customers from rivals, Cirque developed uncontested market space that made the competition irrelevant. Cirque created what the authors call a blue ocean, a previously unknown market space. In blue oceans, demand is created rather than fought over. There is ample opportunity for growth that is both profitable and rapid. In red oceans--that is, in all the industries already existing--companies compete by grabbing for a greater share of limited demand. As the market space gets more crowded, prospects for profits and growth decline. Products turn into commodities, and increasing competition turns the water bloody. There are two ways to create blue oceans. One is to launch completely new industries, as eBay did with online auctions. But it's much more common for a blue ocean to be created from within a red ocean when a company expands the boundaries of an existing industry. In studying more than 150 blue ocean creations in over 30 industries, the authors observed that the traditional units of strategic analysis--company and industry--are of limited use in explaining how and why blue oceans are created. The most appropriate unit of analysis is the strategic move, the set of managerial actions and decisions involved in making a major market-creating business offering. Creating blue oceans builds brands. So powerful is blue ocean strategy, in fact, that a blue ocean strategic move can create brand equity that lasts for decades.

Galaxy Clustering in Early Sloan Digital Sky Survey Redshift Data

NASA Astrophysics Data System (ADS)

Zehavi, Idit; Blanton, Michael R.; Frieman, Joshua A.; Weinberg, David H.; Mo, Houjun J.; Strauss, Michael A.; Anderson, Scott F.; Annis, James; Bahcall, Neta A.; Bernardi, Mariangela; Briggs, John W.; Brinkmann, Jon; Burles, Scott; Carey, Larry; Castander, Francisco J.; Connolly, Andrew J.; Csabai, Istvan; Dalcanton, Julianne J.; Dodelson, Scott; Doi, Mamoru; Eisenstein, Daniel; Evans, Michael L.; Finkbeiner, Douglas P.; Friedman, Scott; Fukugita, Masataka; Gunn, James E.; Hennessy, Greg S.; Hindsley, Robert B.; Ivezić, Željko; Kent, Stephen; Knapp, Gillian R.; Kron, Richard; Kunszt, Peter; Lamb, Donald Q.; Leger, R. French; Long, Daniel C.; Loveday, Jon; Lupton, Robert H.; McKay, Timothy; Meiksin, Avery; Merrelli, Aronne; Munn, Jeffrey A.; Narayanan, Vijay; Newcomb, Matt; Nichol, Robert C.; Owen, Russell; Peoples, John; Pope, Adrian; Rockosi, Constance M.; Schlegel, David; Schneider, Donald P.; Scoccimarro, Roman; Sheth, Ravi K.; Siegmund, Walter; Smee, Stephen; Snir, Yehuda; Stebbins, Albert; Stoughton, Christopher; SubbaRao, Mark; Szalay, Alexander S.; Szapudi, Istvan; Tegmark, Max; Tucker, Douglas L.; Uomoto, Alan; Vanden Berk, Dan; Vogeley, Michael S.; Waddell, Patrick; Yanny, Brian; York, Donald G.

2002-05-01

We present the first measurements of clustering in the Sloan Digital Sky Survey (SDSS) galaxy redshift survey. Our sample consists of 29,300 galaxies with redshifts 5700kms-1<=cz<=39,000kms-1, distributed in several long but narrow (2.5d-5°) segments, covering 690 deg2. For the full, flux-limited sample, the redshift-space correlation length is approximately 8 h-1 Mpc. The two-dimensional correlation function ξ(rp,π) shows clear signatures of both the small-scale, ``fingers-of-God'' distortion caused by velocity dispersions in collapsed objects and the large-scale compression caused by coherent flows, though the latter cannot be measured with high precision in the present sample. The inferred real-space correlation function is well described by a power law, ξ(r)=(r/6.1+/-0.2h-1Mpc)-1.75+/-0.03, for 0.1h-1Mpc<=r<=16h-1Mpc. The galaxy pairwise velocity dispersion is σ12~600+/-100kms-1 for projected separations 0.15h-1Mpc<=rp<=5h-1Mpc. When we divide the sample by color, the red galaxies exhibit a stronger and steeper real-space correlation function and a higher pairwise velocity dispersion than do the blue galaxies. The relative behavior of subsamples defined by high/low profile concentration or high/low surface brightness is qualitatively similar to that of the red/blue subsamples. Our most striking result is a clear measurement of scale-independent luminosity bias at r<~10h-1Mpc: subsamples with absolute magnitude ranges centered on M*-1.5, M*, and M*+1.5 have real-space correlation functions that are parallel power laws of slope ~-1.8 with correlation lengths of approximately 7.4, 6.3, and 4.7 h-1 Mpc, respectively.

Electronic properties of blue phosphorene/graphene and blue phosphorene/graphene-like gallium nitride heterostructures.

PubMed

Sun, Minglei; Chou, Jyh-Pin; Yu, Jin; Tang, Wencheng

2017-07-05

Blue phosphorene (BlueP) is a graphene-like phosphorus nanosheet which was synthesized very recently for the first time [Nano Lett., 2016, 16, 4903-4908]. The combination of electronic properties of two different two-dimensional materials in an ultrathin van der Waals (vdW) vertical heterostructure has been proved to be an effective approach to the design of novel electronic and optoelectronic devices. Therefore, we used density functional theory to investigate the structural and electronic properties of two BlueP-based heterostructures - BlueP/graphene (BlueP/G) and BlueP/graphene-like gallium nitride (BlueP/g-GaN). Our results showed that the semiconducting nature of BlueP and the Dirac cone of G are well preserved in the BlueP/G vdW heterostructure. Moreover, by applying a perpendicular electric field, it is possible to tune the position of the Dirac cone of G with respect to the band edge of BlueP, resulting in the ability to control the Schottky barrier height. For the BlueP/g-GaN vdW heterostructure, BlueP forms an interface with g-GaN with a type-II band alignment, which is a promising feature for unipolar electronic device applications. Furthermore, we discovered that both G and g-GaN can be used as an active layer for BlueP to facilitate charge injection and enhance the device performance.

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.

77 FR 62505 - Combined Notice of Filings #1

Federal Register 2010, 2011, 2012, 2013, 2014

2012-10-15

.... Applicants: Blue Sky East, LLC. Description: Application for Authorization Under Section 203 of the Federal... of Blue Sky East, LLC. Filed Date: 9/18/12. Accession Number: 20120918-5137. Comments Due: 5 p.m. ET...

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

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?

Blue Origin testing

NASA Image and Video Library

2012-04-20

NASA Administrator Charles Bolden (r) discusses the upcoming testing of Blue Origin's BE-3 engine thrust chamber assembly with Steve Knowles, Blue Origin project manager, at the E-1 Test Stand during an April 20, 2012, visit to Stennis Space Center. Blue Origin is one of NASA's partners developing innovative systems to reach low-Earth orbit.

Blue Nevi and Related Tumors.

PubMed

Zembowicz, Artur

2017-09-01

The major entities related to blue nevus are common blue nevus, cellular blue nevus, atypical blue nevus, and malignant blue nevus. These lesions share presence of dermal pigmented dendritic melanocytes derived from embryonal precursors to melanocytes, Schwann cells, and glial cells migrating to the skin from the ventral neural crest. Genetically, blue nevi harbor mutations in G-protein-coupled receptor subunits GNAQ and GNA11. Progression to malignant blue nevus is associated with additional mutations and partial gains and losses of chromosomal material. This article discusses recent advances in pathology of blue nevi with emphasis on differential diagnosis and molecular pathology. Copyright © 2017 Elsevier Inc. All rights reserved.

Vibrio azureus emits blue-shifted light via an accessory blue fluorescent protein.

PubMed

Yoshizawa, Susumu; Karatani, Hajime; Wada, Minoru; Kogure, Kazuhiro

2012-04-01

Luminous marine bacteria usually emit bluish-green light with a peak emission wavelength (λ(max) ) at about 490 nm. Some species belonging to the genus Photobacterium are exceptions, producing an accessory blue fluorescent protein (lumazine protein: LumP) that causes a blue shift, from λ(max)  ≈ 490 to λ(max)  ≈ 476 nm. However, the incidence of blue-shifted light emission or the presence of accessory fluorescent proteins in bacteria of the genus Vibrio has never been reported. From our spectral analysis of light emitted by 16 luminous strains of the genus Vibrio, it was revealed that most strains of Vibrio azureus emit a blue-shifted light with a peak at approximately 472 nm, whereas other Vibrio strains emit light with a peak at around 482 nm. Therefore, we investigated the mechanism underlying this blue shift in V. azureus NBRC 104587(T) . Here, we describe the blue-shifted light emission spectra and the isolation of a blue fluorescent protein. Intracellular protein analyses showed that this strain had a blue fluorescent protein (that we termed VA-BFP), the fluorescent spectrum of which was almost identical to that of the in vivo light emission spectrum of the strain. This result strongly suggested that VA-BFP was responsible for the blue-shifted light emission of V. azureus. © 2012 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

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.

Faint blue counts from formation of dwarf galaxies at z approximately equals 1

NASA Technical Reports Server (NTRS)

Babul, Arif; Rees, Martin J.

1993-01-01

The nature of faint blue objects (FBO's) has been a source of much speculation since their detection in deep CCD images of the sky. Their high surface density argues against them being progenitors of present-day bright galaxies and since they are only weakly clustered on small scales, they cannot be entities that merged together to form present-day galaxies. Babul & Rees (1992) have suggested that the observed faint blue counts may be due to dwarf elliptical galaxies undergoing their initial starburst at z is approximately equal to 1. In generic hierarchical clustering scenarios, however, dwarf galaxy halos (M is approximately 10(exp 9) solar mass) are expected to form at an earlier epoch; for example, typical 10(exp 9) solar mass halos will virialize at z is approximately equal to 2.3 if the power-spectrum for the density fluctuations is that of the standard b = 2 cold dark matter (CDM) model. Under 'ordinary conditions' the gas would rapidly cool, collect in the cores, and undergo star-formation. Conditions at high redshifts are far from 'ordinary'. The intense UV background will prevent the gas in the dwarf halos from cooling, the halos being released from their suspended state only when the UV flux has diminished sufficiently.

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.

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.

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.

Blue diffuse dwarf galaxies: a clearer picture

NASA Astrophysics Data System (ADS)

James, Bethan L.; Koposov, Sergey E.; Stark, Daniel P.; Belokurov, Vasily; Pettini, Max; Olszewski, Edward W.; McQuinn, Kristen B. W.

2017-03-01

The search for chemically unevolved galaxies remains prevalent in the nearby Universe, mostly because these systems provide excellent proxies for exploring in detail the physics of high-z systems. The most promising candidates are extremely metal-poor galaxies (XMPs), I.e. galaxies with <1/10 solar metallicity. However, due to the bright emission-line-based search criteria traditionally used to find XMPs, we may not be sampling the full XMP population. In 2014, we reoriented this search using only morphological properties and uncovered a population of ˜150 'blue diffuse dwarf (BDD) galaxies', and published a sub-sample of 12 BDD spectra. Here, we present optical spectroscopic observations of a larger sample of 51 BDDs, along with their Sloan Digital Sky Survey (SDSS) photometric properties. With our improved statistics, we use direct-method abundances to confirm that BDDs are chemically unevolved (7.43 < 12 + log(O/H) < 8.01), with ˜20 per cent of our sample classified as being XMP galaxies, and find that they are actively forming stars at rates of ˜1-33 × 10-2 M⊙ yr-1 in H II regions randomly embedded in a blue, low-surface-brightness continuum. Stellar masses are calculated from population synthesis models and estimated to be in the range log (M*/M⊙) ≃ 5-9. Unlike other low-metallicity star-forming galaxies, BDDs are in agreement with the mass-metallicity relation at low masses, suggesting that they are not accreting large amounts of pristine gas relative to their stellar mass. BDD galaxies appear to be a population of actively star-forming dwarf irregular (dIrr) galaxies which fall within the class of low-surface-brightness dIrr galaxies. Their ongoing star formation and irregular morphology make them excellent analogues for galaxies in the early Universe.

Dermatoscopy of blue vitiligo.

PubMed

Chandrashekar, L

2009-07-01

Blue vitiligo is a distinct variant of vitiligo characterized by a blue-grey appearance of the skin, which corresponds histologically with absence of epidermal melanocytes and presence of numerous dermal melanophages. A 23-year-old woman of Indian origin with Fitzpatrick skin type V presented with a 1-month history of normoaesthetic depigmented macules over the right forearm, dorsa of the hands and right areola. The macule over the right forearm had a bluish tinge. A clinical diagnosis of vitiligo vulgaris with blue vitiligo was made. Dermatoscopy of the interface between the blue macule and the hypopigmented macule revealed a linear depigmented macule in the centre with multiple blue dots and absence of epidermal melanin on the side of the blue macule, and reticular pigmentation with a few depigmented macules and scattered blue dots over the side of the hypopigmented macule. Blue vitiligo was described previously in a patient seropositive for human immunodeficiency virus, and believed to represent postinflammatory hyperpigmentation in areas bordering the vitiliginous patches as a result of psoralen ultraviolet A treatment. This case is unusual because of its rarity and the description of the associated dermatoscopical findings.

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

Slow-blue nuclear hypervariables in PanSTARRS-1

DOE PAGES

Lawrence, A.; Bruce, A. G.; MacLeod, C.; ...

2016-09-08

We discuss 76 large amplitude transients (Δm > 1.5) occurring in the nuclei of galaxies, nearly all with no previously known active galactic nucleus (AGN). They have been discovered as part of the Pan-STARRS1 (PS1) 3π survey, by comparison with Sloan Digital Sky Survey (SDSS) photometry a decade earlier, and then monitored with the Liverpool Telescope, and studied spectroscopically with the William Herschel Telescope (WHT). Based on colours, light-curve shape, and spectra, these transients fall into four groups. A few are misclassified stars or objects of unknown type. Some are red/fast transients and are known or likely nuclear supernovae. Amore » few are either radio sources or erratic variables and so likely blazars. However the majority (~66 per cent) are blue and evolve slowly, on a time-scale of years. Spectroscopy shows them to be AGN at z ~0.3 – 1.4, which must have brightened since the SDSS photometry by around an order of magnitude. It is likely that these objects were in fact AGN a decade ago, but too weak to be recognized by SDSS; they could then be classed as ‘hypervariable’ AGN. By searching the SDSS Stripe 82 quasar database, we find 15 similar objects. We discuss several possible explanations for these slow-blue hypervariables – (i) unusually luminous tidal disruption events; (ii) extinction events; (iii) changes in accretion state; and (iv) large amplitude microlensing by stars in foreground galaxies. A mixture of explanations (iii) and (iv) seems most likely. As a result, both hold promise of considerable new insight into the AGN phenomenon.« less

Slow-blue nuclear hypervariables in PanSTARRS-1

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

Lawrence, A.; Bruce, A. G.; MacLeod, C.

We discuss 76 large amplitude transients (Δm > 1.5) occurring in the nuclei of galaxies, nearly all with no previously known active galactic nucleus (AGN). They have been discovered as part of the Pan-STARRS1 (PS1) 3π survey, by comparison with Sloan Digital Sky Survey (SDSS) photometry a decade earlier, and then monitored with the Liverpool Telescope, and studied spectroscopically with the William Herschel Telescope (WHT). Based on colours, light-curve shape, and spectra, these transients fall into four groups. A few are misclassified stars or objects of unknown type. Some are red/fast transients and are known or likely nuclear supernovae. Amore » few are either radio sources or erratic variables and so likely blazars. However the majority (~66 per cent) are blue and evolve slowly, on a time-scale of years. Spectroscopy shows them to be AGN at z ~0.3 – 1.4, which must have brightened since the SDSS photometry by around an order of magnitude. It is likely that these objects were in fact AGN a decade ago, but too weak to be recognized by SDSS; they could then be classed as ‘hypervariable’ AGN. By searching the SDSS Stripe 82 quasar database, we find 15 similar objects. We discuss several possible explanations for these slow-blue hypervariables – (i) unusually luminous tidal disruption events; (ii) extinction events; (iii) changes in accretion state; and (iv) large amplitude microlensing by stars in foreground galaxies. A mixture of explanations (iii) and (iv) seems most likely. As a result, both hold promise of considerable new insight into the AGN phenomenon.« less

The Blue Bottle Revisited.

ERIC Educational Resources Information Center

Vandaveer, Walter R., IV; Mosher, Mel

1997-01-01

Presents a modification of the classic Blue Bottle demonstration that involves the alkaline glucose reduction of methylene blue. Uses other indicators in the classic Blue Bottle to produce a rainbow of colors. (JRH)

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.

Direct Aerosol Radiative Forcing from Combined A-Train Observations - Preliminary Comparisons with AeroCom Models and Pathways to Observationally Based All-sky Estimates

NASA Astrophysics Data System (ADS)

Redemann, J.; Livingston, J. M.; Shinozuka, Y.; Kacenelenbogen, M. S.; Russell, P. B.; LeBlanc, S. E.; Vaughan, M.; Ferrare, R. A.; Hostetler, C. A.; Rogers, R. R.; Burton, S. P.; Torres, O.; Remer, L. A.; Stier, P.; Schutgens, N.

2014-12-01

We describe a technique for combining CALIOP aerosol backscatter, MODIS spectral AOD (aerosol optical depth), and OMI AAOD (absorption aerosol optical depth) retrievals for the purpose of estimating full spectral sets of aerosol radiative properties, and ultimately for calculating the 3-D distribution of direct aerosol radiative forcing. We present results using one year of data collected in 2007 and show comparisons of the aerosol radiative property estimates to collocated AERONET retrievals. Use of the recently released MODIS Collection 6 data for aerosol optical depths derived with the dark target and deep blue algorithms has extended the coverage of the multi-sensor estimates towards higher latitudes. Initial calculations of seasonal clear-sky aerosol radiative forcing based on our multi-sensor aerosol retrievals compare well with over-ocean and top of the atmosphere IPCC-2007 model-based results, and with more recent assessments in the "Climate Change Science Program Report: Atmospheric Aerosol Properties and Climate Impacts" (2009). For the first time, we present comparisons of our multi-sensor aerosol direct radiative forcing estimates to values derived from a subset of models that participated in the latest AeroCom initiative. We discuss the major challenges that exist in extending our clear-sky results to all-sky conditions. On the basis of comparisons to suborbital measurements, we present some of the limitations of the MODIS and CALIOP retrievals in the presence of adjacent or underlying clouds. Strategies for meeting these challenges are discussed.

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.

(EDMUNDS, WA) WILDLAND FIRE EMISSIONS MODELING: INTEGRATING BLUESKY AND SMOKE

EPA Science Inventory

This presentation is a status update of the BlueSky emissions modeling system. BlueSky-EM has been coupled with the Sparse Matrix Operational Kernel Emissions (SMOKE) system, and is now available as a tool for estimating emissions from wildland fires

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.

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.

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.

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

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

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

PubMed

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

2000-06-10

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

The Role of Major Gas-rich Mergers on the Evolution of Galaxies from the Blue Cloud to the Red Sequence

NASA Astrophysics Data System (ADS)

Guo, Rui; Hao, Cai-Na; Xia, X. Y.; Mao, Shude; Shi, Yong

2016-07-01

With the aim of exploring the fast evolutionary path from the blue cloud of star-forming galaxies to the red sequence of quiescent galaxies in the local universe, we select a local advanced merging infrared luminous and ultraluminous galaxy (adv-merger (U)LIRGs) sample and perform careful dust extinction corrections to investigate their positions in the star formation rate-M *, u - r, and NUV - r color-mass diagrams. The sample consists of 89 (U)LIRGs at the late merger stage, obtained from cross-correlating the Infrared Astronomical Satellite Point Source Catalog Redshift Survey and 1 Jy ULIRGs samples with the Sloan Digital Sky Survey DR7 database. Our results show that 74 % +/- 5 % of adv-merger (U)LIRGs are localized above the 1σ line of the local star-forming galaxy main sequence. We also find that all adv-merger (U)LIRGs are more massive than and as blue as the blue cloud galaxies after corrections for Galactic and internal dust extinctions, with 95 % +/- 2 % and 81 % +/- 4 % of them outside the blue cloud on the u - r and NUV - r color-mass diagrams, respectively. These results, combined with the short timescale for exhausting the molecular gas reservoir in adv-merger (U)LIRGs (3× {10}7 to 3× {10}8 years), imply that the adv-merger (U)LIRGs are likely at the starting point of the fast evolutionary track previously proposed by several groups. While the number density of adv-merger (U)LIRGs is only ˜ 0.1 % of the blue cloud star-forming galaxies in the local universe, this evolutionary track may play a more important role at high redshift.

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.

Corneal edema and permanent blue discoloration of a silicone intraocular lens by methylene blue.

PubMed

Stevens, Scott; Werner, Liliana; Mamalis, Nick

2007-01-01

To report a silicone intraocular lens (IOL) stained blue by inadvertent intraoperative use of methylene blue instead of trypan blue and the results of experimental staining of various lens materials with different concentrations of the same dye. A "blue dye" was used to enhance visualization during capsulorhexis in a patient undergoing phacoemulsification with implantation of a three-piece silicone lens. Postoperatively, the patient presented with corneal edema and a discolored IOL. Various IOL materials were experimentally stained using methylene blue. Sixteen lenses (4 silicone, 4 hydrophobic acrylic, 4 hydrophilic acrylic, and 4 polymethylmethacrylate) were immersed in 0.5 mL of methylene blue at concentrations of 1%, 0.1%, 0.01%, and 0.001%. These lenses were grossly and microscopically evaluated for discoloration 6 and 24 hours after immersion. The corneal edema resolved within 1 month after the initial surgical procedure. After explantation, gross and microscopic analyses of the explanted silicone lens revealed that its surface and internal substance had been permanently stained blue. In the experimental study, all of the lenses except the polymethylmethacrylate lenses were permanently stained by methylene blue. The hydrophilic acrylic lenses showed the most intense blue staining in all dye concentrations. This is the first clinicopathological report of IOL discoloration due to intraocular use of methylene blue. This and other tissue dyes may be commonly found among surgical supplies in the operating room and due diligence is necessary to avoid mistaking these dyes for those commonly used during ocular surgery.

Blue nightshade poisoning

MedlinePlus

... when someone eats parts of the blue nightshade plant. This article is for information only. DO NOT ... is found in the blue nightshade ( Solanum dulcamara ) plant, especially in the fruit and leaves.

What Colour Is a Shadow?

ERIC Educational Resources Information Center

Hughes, S. W.

2009-01-01

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

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.

Basic Color Terms (BCTs) and Categories (BCCs) in Three Dialects of the Spanish Language: Interaction Between Cultural and Universal Factors.

PubMed

Lillo, Julio; González-Perilli, Fernando; Prado-León, Lilia; Melnikova, Anna; Álvaro, Leticia; Collado, José A; Moreira, Humberto

2018-01-01

Two experiments were performed to identify and compare the Basic Color Terms (BCTs) and the Basic Color Categories (BCCs) included in three dialects (Castilian, Mexican, and Uruguayan) of the Spanish language. Monolexemic Elicited lists were used in the first experiment to identify the BCTs of each dialect. Eleven BCTs appeared for the Spanish and the Mexican, and twelve did so for the Uruguayan. The six primary BCTs ( rojo "red," verde "green," amarillo "yellow," azul "blue," negro "black," and blanco "white") appeared in the three dialects. This occurred for only three derived BCTs ( gris "gray," naranja "orange," and rosa "pink") but not for the other five derived BCTs ( celeste "sky blue," marrón "brown," café "brown," morado "purple," and violeta "purple"). Color transitions were used in the second experiment for two different tasks. Extremes naming task was used to determine the relation between two different dialects' BCTs: equality, equivalence or difference. The results provided the first evidence for marrón "brown" and café "brown" being equivalent terms for the same BCC (brown in English) as is the case of morado "purple" and violeta "purple." Uruguayan celeste "sky blue" had no equivalent BCT in the other two dialects. Boundary delimitation task required the selection of the color in the boundary between two categories. The task was used to reasonably estimate the volume occupied by each BCC in the color space considering its chromatic area and lightness range. Excluding sky blue ( celeste "sky blue") and blue ( azul "blue"), the other BCCs color volumes were similar across the three dialects. Uruguayan sky blue and blue volumes conjointly occupied the portion of the color space corresponding to the Castilian and Mexican blue BCC. The fact that the BCT celeste "sky blue" only appeared in Uruguayan very probably derived from specific cultural factors (the use of the color in the flags and the arrival of an important number of Italian immigrants

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…

[Acute blue urticaria following subcutaneous injection of patent blue dye].

PubMed

Hamelin, A; Vial-Dupuy, A; Lebrun-Vignes, B; Francès, C; Soria, A; Barete, S

2015-11-01

Patent blue (PB) is a lymphatic vessel dye commonly used in France for sentinel lymph node detection in breast cancer, and less frequently in melanoma, and which may induce hypersensitivity reactions. We report a case of acute blue urticaria occurring within minutes of PB injection. Ten minutes after PB injection for sentinel lymph node detection during breast cancer surgery, a 49-year-old woman developed generalised acute blue urticaria and eyelid angioedema without bronchospasm or haemodynamic disturbance, but requiring discontinuation of surgery. Skin testing using PB and the anaesthetics given were run 6 weeks after the episode and confirmed PB allergy. PB was formally contra-indicated. Immediate hypersensitivity reactions to PB have been reported for between 0.24 and 2.2% of procedures. Such reactions are on occasion severe, chiefly involving anaphylactic shock. Two mechanisms are probably associated: non-specific histamine release and/or an IgE-mediated mechanism. Skin tests are helpful in confirming the diagnosis of PB allergy. Blue acute urticaria is one of the clinical manifestations of immediate hypersensitivity reactions to patent blue dye. Skin tests must be performed 6 weeks after the reaction in order to confirm the diagnosis and formally contra-indicate this substance. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

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…

Jupiter in blue, ultraviolet and near infrared

NASA Technical Reports Server (NTRS)

2000-01-01

These three images of Jupiter, taken through the narrow angle camera of NASA's Cassini spacecraft from a distance of 77.6 million kilometers (48.2 million miles) on October 8, reveal more than is apparent to the naked eye through a telescope.

The image on the left was taken through the blue filter. The one in the middle was taken in the ultraviolet. The one on the right was taken in the near infrared.

The blue-light filter is within the part of the electromagnetic spectrum detectable by the human eye. The appearance of Jupiter in this image is, consequently, very familiar. The Great Red Spot (below and to the right of center) and the planet's well-known banded cloud lanes are obvious. The brighter bands of clouds are called zones and are probably composed of ammonia ice particles. The darker bands are called belts and are made dark by particles of unknown composition intermixed with the ammonia ice.

Jupiter's appearance changes dramatically in the ultraviolet and near infrared images. These images are near negatives of each other and illustrate the way in which observations in different wavelength regions can reveal different physical regimes on the planet.

All gases scatter sunlight efficiently at short wavelengths; this is why the sky appears blue on Earth. The effect is even more pronounced in the ultraviolet. The gases in Jupiter's atmosphere, above the clouds, are no different. They scatter strongly in the ultraviolet, making the deep banded cloud layers invisible in the middle image. Only the very high altitude haze appears dark against the bright background. The contrast is reversed in the near infrared, where methane gas, abundant on Jupiter but not on Earth, is strongly absorbing and therefore appears dark. Again the deep clouds are invisible, but now the high altitude haze appears relatively bright against the dark background. High altitude haze is seen over the poles and the equator.

The Great Red Spot, prominent in all images, is

77 FR 67641 - Combined Notice of Filings #1

Federal Register 2010, 2011, 2012, 2013, 2014

2012-11-13

.... Applicants: Blue Sky East, LLC. Description: Application for Authorization Under Section 203 of the Federal Power Act and Request for Waivers, Confidential Treatment, and Shortened Comment Period of Blue Sky East.... Docket Numbers: ER13-309-000. Applicants: Cheyenne Light, Fuel and Power Company. Description: OATT...

77 FR 40875 - Combined Notice of Filings #2

Federal Register 2010, 2011, 2012, 2013, 2014

2012-07-11

... following exempt wholesale generator filings: Docket Numbers: EG12-81-000. Applicants: Blue Sky East, LLC. Description: Notice of Self-Certification of Exempt Wholesale Generator Status of Blue Sky East, LLC. Filed.... Docket Numbers: ER12-2146-000 Applicants: Interstate Power and Light Company Description: Cancellation of...

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.

SkyMapper Southern Survey: First Data Release (DR1)

NASA Astrophysics Data System (ADS)

Wolf, Christian; Onken, Christopher A.; Luvaul, Lance C.; Schmidt, Brian P.; Bessell, Michael S.; Chang, Seo-Won; Da Costa, Gary S.; Mackey, Dougal; Martin-Jones, Tony; Murphy, Simon J.; Preston, Tim; Scalzo, Richard A.; Shao, Li; Smillie, Jon; Tisserand, Patrick; White, Marc C.; Yuan, Fang

2018-02-01

We present the first data release of the SkyMapper Southern Survey, a hemispheric survey carried out with the SkyMapper Telescope at Siding Spring Observatory in Australia. Here, we present the survey strategy, data processing, catalogue construction, and database schema. The first data release dataset includes over 66 000 images from the Shallow Survey component, covering an area of 17 200 deg2 in all six SkyMapper passbands uvgriz, while the full area covered by any passband exceeds 20 000 deg2. The catalogues contain over 285 million unique astrophysical objects, complete to roughly 18 mag in all bands. We compare our griz point-source photometry with Pan-STARRS1 first data release and note an RMS scatter of 2%. The internal reproducibility of SkyMapper photometry is on the order of 1%. Astrometric precision is better than 0.2 arcsec based on comparison with Gaia first data release. We describe the end-user database, through which data are presented to the world community, and provide some illustrative science queries.

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.

Jagua blue derived from Genipa americana L. fruit: A natural alternative to commonly used blue food colorants?

PubMed

Brauch, J E; Zapata-Porras, S P; Buchweitz, M; Aschoff, J K; Carle, R

2016-11-01

Due to consumers' increasing health awareness, food industry aims at replacing synthetic dyes by natural counterparts. The substitution of blue synthetic dyes is particularly challenging since current natural alternatives such as phycocyanin (Spirulina) suffer from poor stability. Jagua blue (produced from Genipa americana L. fruit) might represent a potential novel blue pigment source. However, only little is known about its color properties, and application in food systems. Therefore, the blue color and the stability of Jagua blue were assessed for the first time and compared to commonly used colorants, namely, Spirulina, brilliant blue FCF (Blue no. 1), and indigo carmine (Blue no. 2). The reaction rate of Jagua blue was independent of its concentration, confirming thermal degradation to follow first-order kinetics. Between pH 3.6 and 5.0, the color hue of Jagua blue solutions was similar to that of Blue no. 2. However, Jagua blue revealed markedly higher storage stabilities (t 1/2 =86-105days) than Blue no. 2 (t 1 /2 ≤9days) and was less susceptible to acidic pH of 3.6 (t 1 /2 =86days) than Spirulina (t 1 /2 =70days). High negative b* values (blueness) of colored gelatin gels were only obtained for Jagua blue and Spirulina, and the former exhibited higher light stabilities (t 1 /2 =15days) than Spirulina gels (t 1 /2 =4days). Our findings indicate Jagua blue to be a most promising alternative to synthetic dyes, providing relevant information regarding potential food applications. Copyright © 2016 Elsevier Ltd. All rights reserved.

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

Variations on the "Blue-Bottle" Demonstration Using Food Items That Contain FD&C Blue #1

ERIC Educational Resources Information Center

Staiger, Felicia A.; Peterson, Joshua P.; Campbell, Dean J.

2015-01-01

Erioglaucine dye (FD&C Blue #1) can be used instead of methylene blue in the classic "blue-bottle" demonstration. Food items containing FD&C Blue #1 and reducing species such as sugars can therefore be used at the heart of this demonstration, which simply requires the addition of strong base such as sodium hydroxide lye.

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/.

Measuring Blue Space Visibility and 'Blue Recreation' in the Everyday Lives of Children in a Capital City.

PubMed

Pearson, Amber L; Bottomley, Ross; Chambers, Tim; Thornton, Lukar; Stanley, James; Smith, Moira; Barr, Michelle; Signal, Louise

2017-05-26

Blue spaces (water bodies) may promote positive mental and physical health through opportunities for relaxation, recreation, and social connections. However, we know little about the nature and extent of everyday exposure to blue spaces, particularly in settings outside the home or among children, nor whether exposure varies by individual or household characteristics. Wearable cameras offer a novel, reliable method for blue space exposure measurement. In this study, we used images from cameras worn over two days by 166 children in Wellington, New Zealand, and conducted content and blue space quantification analysis on each image ( n = 749,389). Blue space was identified in 24,721 images (3.6%), with a total of 23 blue recreation events. Visual exposure and participation in blue recreation did not differ by ethnicity, weight status, household deprivation, or residential proximity to the coastline. Significant differences in both visual exposure to blue space and participation in blue recreation were observed, whereby children from the most deprived schools had significantly higher rates of blue space exposure than children from low deprivation schools. Schools may be important settings to promote equitable blue space exposures. Childhood exposures to blue space may not follow the expected income inequality trends observed among adults.

Evaluation of a wildfire smoke forecasting system as a tool for public health protection.

PubMed

Yao, Jiayun; Brauer, Michael; Henderson, Sarah B

2013-10-01

Exposure to wildfire smoke has been associated with cardiopulmonary health impacts. Climate change will increase the severity and frequency of smoke events, suggesting a need for enhanced public health protection. Forecasts of smoke exposure can facilitate public health responses. We evaluated the utility of a wildfire smoke forecasting system (BlueSky) for public health protection by comparing its forecasts with observations and assessing their associations with population-level indicators of respiratory health in British Columbia, Canada. We compared BlueSky PM2.5 forecasts with PM2.5 measurements from air quality monitors, and BlueSky smoke plume forecasts with plume tracings from National Oceanic and Atmospheric Administration Hazard Mapping System remote sensing data. Daily counts of the asthma drug salbutamol sulfate dispensations and asthma-related physician visits were aggregated for each geographic local health area (LHA). Daily continuous measures of PM2.5 and binary measures of smoke plume presence, either forecasted or observed, were assigned to each LHA. Poisson regression was used to estimate the association between exposure measures and health indicators. We found modest agreement between forecasts and observations, which was improved during intense fire periods. A 30-μg/m3 increase in BlueSky PM2.5 was associated with an 8% increase in salbutamol dispensations and a 5% increase in asthma-related physician visits. BlueSky plume coverage was associated with 5% and 6% increases in the two health indicators, respectively. The effects were similar for observed smoke, and generally stronger in very smoky areas. BlueSky forecasts showed modest agreement with retrospective measures of smoke and were predictive of respiratory health indicators, suggesting they can provide useful information for public health protection.

Allergic contact dermatitis caused by the blue pigment VINAMON® Blue BX FW - a phthalocyanine blue in a vinyl glove.

PubMed

Weimann, Stefanie; Skudlik, Christoph; John, Swen Malte

2010-10-01

A 44-year-old metalworker suffered from severe hand eczema in spite of treatment with corticosteroid ointments. He had been using protective cotton gloves with blue PVC anti-slip dots on the finger tips. On clinical examination, the backs of both hands were erythematous and thickened while the finger tips showed vesicles. There was a positive patch test reaction to the blue PVC dots of an unworn cotton glove at 72, 96, 120 hours. To identify the causative chemicals, we carried out further patch tests using ingredients of the glove and cupric sulfate. The patient reacted to the blue dye VYNAMON(®) Blue BX FW (PB 15) at two concentrations - 10% at 72 and 96 hours, and 50% at 48 and 72 hours. This dye is a very strong and brilliant blue with red-copper tones and resistant to fire and weathering. The cupric-phthalocyanine complexes are used as pigments in cosmetics (e. g. CI 74160, 74180, 74260). To the best of our knowledge, no allergic reactions to this dye have been described, particularly not in gloves. © The Authors • Journal compilation © Blackwell Verlag GmbH, Berlin.

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

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.

75 FR 65525 - Anthem Blue Cross Blue Shield, Claim Management Services, Inc. Operations, a Division of...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-10-25

... DEPARTMENT OF LABOR Employment and Training Administration [TA-W-74,327] Anthem Blue Cross Blue Shield, Claim Management Services, Inc. Operations, a Division of Wellpoint, Inc., Green Bay, WI; Notice... former workers of Anthem Blue Cross Blue Shield, Claim Management Services, Inc. Operations, a Division...

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.

Grey Area in the Blue Skies.

ERIC Educational Resources Information Center

Allen, Craig M.

A number of flight accidents in recent years have made the use of helicopters in news coverage controversial. Radio or television reporters are sometimes asked to fly under unsafe conditions simply because competing stations have sent up their reporters. Although pilots have the right to refuse to fly if they feel conditions are dubious, they too…

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).

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

DOE PAGES

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

2016-12-06

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

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

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

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

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

The 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.

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

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.

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 significance of blue color in dermatoscopy.

PubMed

Popadić, Mirjana; Sinz, Christoph; Kittler, Harald

2017-03-01

Skin lesions with blue color are frequently excised to rule out malignancy. The objective of the present study was to investigate the significance of blue color. We retrospectively scanned dermatoscopic images for blue color and classified them according to pattern analysis. Of 1,123 pigmented skin lesions, 144 (12.8 %) showed blue color, 92 of which (63.9 %) were malignant. Among lesions with blue color, the most common benign diagnoses were nevi (n = 35, 24.3 %) and seborrheic keratoses (n = 8, 5.6 %). Of 103 (71.5 %) lesions with a structureless blue pattern, eight (7.8 %) were entirely blue and 95 (92.2 %) were partly blue, of which 81 (78.6 %) showed peripheral or patchy and 14 (13.6 %) central blue color. Most lesions with peripheral or patchy blue color were melanomas (n = 47, 58 %), whereas most lesions with central blue color were nevi (n = 9, 64.3 %). Of 28 lesions with blue clods, 17 (60.7 %) were basal cell carcinomas. With respect to malignancy, the positive predictive value of blue color was 63.9 % (95 % CI: 56.0-71.8 %). Among malignant lesions with blue color, structureless peripheral or patchy blue color is a clue for melanoma, while blue clods point to basal cell carcinoma. Pitfalls include seborrheic keratoses, which may show blue color, as well as some nevi, especially combined nevi. © 2017 Deutsche Dermatologische Gesellschaft (DDG). Published by John Wiley & Sons Ltd.

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

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

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.

Blue Ocean Thinking

ERIC Educational Resources Information Center

Orem, Donna

2016-01-01

This article describes a concept called the "blue ocean thinking strategy," developed by W. Chan Kim and Renée Mauborgne, professors at INSEAD, an international graduate school of business in France. The "blue ocean" thinking strategy considers opportunities to create new markets for services, rather than focusing solely on…

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

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.

Measuring Blue Space Visibility and ‘Blue Recreation’ in the Everyday Lives of Children in a Capital City

PubMed Central

Pearson, Amber L.; Bottomley, Ross; Chambers, Tim; Thornton, Lukar; Stanley, James; Smith, Moira; Barr, Michelle; Signal, Louise

2017-01-01

Blue spaces (water bodies) may promote positive mental and physical health through opportunities for relaxation, recreation, and social connections. However, we know little about the nature and extent of everyday exposure to blue spaces, particularly in settings outside the home or among children, nor whether exposure varies by individual or household characteristics. Wearable cameras offer a novel, reliable method for blue space exposure measurement. In this study, we used images from cameras worn over two days by 166 children in Wellington, New Zealand, and conducted content and blue space quantification analysis on each image (n = 749,389). Blue space was identified in 24,721 images (3.6%), with a total of 23 blue recreation events. Visual exposure and participation in blue recreation did not differ by ethnicity, weight status, household deprivation, or residential proximity to the coastline. Significant differences in both visual exposure to blue space and participation in blue recreation were observed, whereby children from the most deprived schools had significantly higher rates of blue space exposure than children from low deprivation schools. Schools may be important settings to promote equitable blue space exposures. Childhood exposures to blue space may not follow the expected income inequality trends observed among adults. PMID:28587134

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.

76 FR 19466 - Wellpoint, Inc. D/B/A/Anthem Blue Cross & Blue Shield, et al.; Amended Certification Regarding...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-04-07

.../B/A/Anthem Blue Cross & Blue Shield, et al.; Amended Certification Regarding Eligibility To Apply for Worker Adjustment Assistance TA-W-74,895 Wellpoint, Inc. D/B/A/Anthem Blue Cross & Blue Shield... Enterprise Provider Data Management Team North Haven, Connecticut TA-W-74,895F Wellpoint, Inc. D/B/A/Blue...

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.…

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

Tunable photonic crystals with partial bandgaps from blue phase colloidal crystals and dielectric-doped blue phases.

PubMed

Stimulak, Mitja; Ravnik, Miha

2014-09-07

Blue phase colloidal crystals and dielectric nanoparticle/polymer doped blue phases are demonstrated to combine multiple components with different symmetries in one photonic material, creating a photonic crystal with variable and micro-controllable photonic band structure. In this composite photonic material, one contribution to the band structure is determined by the 3D periodic birefringent orientational profile of the blue phases, whereas the second contribution emerges from the regular array of the colloidal particles or from the dielectric/nanoparticle-doped defect network. Using the planewave expansion method, optical photonic bands of the blue phase I and II colloidal crystals and related nanoparticle/polymer doped blue phases are calculated, and then compared to blue phases with no particles and to face-centred-cubic and body-centred-cubic colloidal crystals in isotropic background. We find opening of local band gaps at particular points of Brillouin zone for blue phase colloidal crystals, where there were none in blue phases without particles or dopants. Particle size and filling fraction of the blue phase defect network are demonstrated as parameters that can directly tune the optical bands and local band gaps. In the blue phase I colloidal crystal with an additionally doped defect network, interestingly, we find an indirect total band gap (with the exception of one point) at the entire edge of SC irreducible zone. Finally, this work demonstrates the role of combining multiple - by symmetry - differently organised components in one photonic crystal material, which offers a novel approach towards tunable soft matter photonic materials.

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

Optimum Design Parameters of Box Window DSF Office at Different Glazing Types under Sub Interval of Intermediate Sky Conditions (20-40 klux)

NASA Astrophysics Data System (ADS)

Elayeb, O. K.; Alghoul, M. A.; Sopian, K.; Khrita, N. G.

2017-11-01

Despite Double skin façade (DSF) buildings are widely deployed worldwide, daylighting strategy is not commonly incorporated in these buildings compare to other strategies. Therefore, further theoretical and experimental studies would lead to adopting daylighting strategy in DSF office buildings. The aim of this study is to investigate the daylighting performance of office building at different design parameters of box window DSF using different glazing types under sub interval of intermediate sky conditions (20-40) klux using the (IES VE) simulation tool from Integrated Environmental Solutions - Virtual Environment. The implemented design parameters are window wall ratio (WWR) of internal façade (10-100) %, cavity depth (CD) of DSF (1-2.5) m and different glazing types. The glazing types were selected from the list available in the (IES VE) simulation tool. After series of evaluations, bronze tinted coating (STOPSOL) is implemented for the exterior façade while clear float, clear reflective coating (STOPSOL), grey and brown tinted coating (Anti-sun float) and blue coating tinted (SUNCOOL float) are implemented for the interior façade. In this paper, several evaluation parameters are used to quantify the optimum design parameters that would balance the daylighting requirements of a box window DSF office versus sky conditions range (20-40) klux. The optimum design parameters of DSF office building obtained under different glazing types are highlighted as follows. When using bronze tinted coating (STOPSOL) for the exterior façade, the glazing types of interior façade that showed superior daylighting performance of DSF office at (CD of 1.0m with WWR of 70%), (CD of 1.5m with WWR of 70%), (CD of 2.0m with WWR of 70%) and (CD of 2.0m with WWR of 70%) are grey tinted coating (Anti-sun float), clear reflective coating (STOPSOL), brown tinted coating (Anti-sun float), and clear float glazing respectively. Blue Coating tinted (SUNCOOL float) of interior façade glazing

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.

21 CFR 133.184 - Roquefort cheese, sheep's milk blue-mold, and blue-mold cheese from sheep's milk.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 2 2012-04-01 2012-04-01 false Roquefort cheese, sheep's milk blue-mold, and blue-mold cheese from sheep's milk. 133.184 Section 133.184 Food and Drugs FOOD AND DRUG ADMINISTRATION..., sheep's milk blue-mold, and blue-mold cheese from sheep's milk. (a) Description. (1) Roquefort cheese...

21 CFR 133.184 - Roquefort cheese, sheep's milk blue-mold, and blue-mold cheese from sheep's milk.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 2 2014-04-01 2014-04-01 false Roquefort cheese, sheep's milk blue-mold, and blue-mold cheese from sheep's milk. 133.184 Section 133.184 Food and Drugs FOOD AND DRUG ADMINISTRATION..., sheep's milk blue-mold, and blue-mold cheese from sheep's milk. (a) Description. (1) Roquefort cheese...

21 CFR 133.184 - Roquefort cheese, sheep's milk blue-mold, and blue-mold cheese from sheep's milk.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 2 2013-04-01 2013-04-01 false Roquefort cheese, sheep's milk blue-mold, and blue-mold cheese from sheep's milk. 133.184 Section 133.184 Food and Drugs FOOD AND DRUG ADMINISTRATION..., sheep's milk blue-mold, and blue-mold cheese from sheep's milk. (a) Description. (1) Roquefort cheese...

78 FR 29362 - Combined Notice of Filings #1

Federal Register 2010, 2011, 2012, 2013, 2014

2013-05-20

...-006; ER11-4029-005; ER10-2463-005. Applicants: Blue Sky East, LLC, Canandaigua Power Partners I, LLC...: Supplement to April 29, 2013 Notice of Change in Status of Blue Sky East, LLC, et al. Filed Date: 5/9/13...: Cheyenne Light, Fuel and Power Company. Description: Order No. 1000 Compliance Filing to be effective 10/1...

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.

Blues fans and suicide acceptability.

PubMed

Stack, S

2000-01-01

Research has neglected the possible impact of the blues music subculture on suicide acceptability (SA). The sad themes in the blues may attract suicidal persons and reinforce their suicidal moods and attitudes. The present study performs the first test of the thesis that associates SA with being a blues fan. It uses data on a national sample of 961 adults drawn from the General Social Survey of 1993. The results of a multivariate logistic regression analysis found that blues fans were no more accepting of suicide than nonfans. However, blues fanship was found to have substantial indirect effects on SA through its influence on such factors as lowered religiosity levels, the most important predictor of SA. Race-specific analyses found more support for the model for whites than for African Americans.

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).

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

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.

Learning the Blues. [Lesson Plan].

ERIC Educational Resources Information Center

2001

This lesson introduces students to the "blues," one of the most distinctive and influential elements of African-American musical tradition. With this lesson plan, students can take a virtual field trip to Memphis, Tennessee, one of the prominent centers of blues activities, and explore the history of the blues in the work of W. C. Handy…

Searching for M Dwarf Flares in Raptor-Q All-sky Photometric Data

NASA Astrophysics Data System (ADS)

Wolfe, Tristan; Wozniak, P. R.; Vestrand, Tom

2012-10-01

Stellar flares are releases of magnetic energy that cause emissions of a wide range across the electromagnetic spectrum. Flares of M dwarf stars are characterized by a large increase in blue and near-UV emissions, causing an increase in several magnitudes within minutes (Hilton et al, AJ, 2010). Exoplanets of several Earth masses have been discovered orbiting M dwarfs, so the search for M dwarf flares is very important, as the planets' atmospheres and habitability may be affected by these bursts in energy. Using data from Los Alamos National Labs' Raptor-Q telescope at Fenton Hill, NM, we are developing an automated method of detecting M dwarf flares. Raptor-Q operates robotically and, with five cameras, collects over 10,000 images of 90% of the sky above 12 degrees elevation in a given night, with a sensitivity up to magnitude R=10 (Wren et al, Proc SPIE, 2010), and automatically provides photometric and astrometric reductions of its images. A prototype pipeline has been developed using Python that looks for transient light curves (quick changes in magnitude over time) in Raptor-Q's data. These light curves will then be analyzed for characteristics of stellar flares, and cross-correlated with published catalogs to determine stellar type and any previous observations of flares.

Morphological responses of wheat to blue light

NASA Technical Reports Server (NTRS)

Barnes, C.; Bugbee, B.

1992-01-01

Blue light significantly increased tillering in wheat (Triticum aestivum L.) plants grown at the same photosynthetic photon flux (PPF). Plants were grown under two levels of blue light (400-500 nm) in a controlled environment with continuous irradiation. Plants received either 50 micromoles m-2 s-1 of blue light or 2 micromoles m-2 s-1 blue light from filtered metal halide lamps at a total irradiance of 200 micromoles m-2 s-1 PPF (400-700 nm). Plants tillered an average of 25% more under the higher level of blue light. Blue light also caused a small, but consistent, increase in main culm development, measured as Haun stage. Leaf length was reduced by higher levels of blue light, while plant dry-mass was not significantly affected by blue light. Applying the principle of equivalent light action, the results suggest that tillering and leaf elongation are mediated by the blue-UV light receptor(s) because phytochrome photoequilibrium for each treatment were nearly identical.

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.

Blue ellipticals in compact groups

NASA Technical Reports Server (NTRS)

Zepf, Stephen E.; Whitmore, Bradley C.

1990-01-01

By studying galaxies in compact groups, the authors examine the hypothesis that mergers of spiral galaxies make elliptical galaxies. The authors combine dynamical models of the merger-rich compact group environment with stellar evolution models and predict that roughly 15 percent of compact group ellipticals should be 0.15 mag bluer in B - R color than normal ellipticals. The published colors of these galaxies suggest the existence of this predicted blue population, but a normal distribution with large random errors can not be ruled out based on these data alone. However, the authors have new ultraviolet blue visual data which confirm the blue color of the two ellipticals with blue B - R colors for which they have their own colors. This confirmation of a population of blue ellipticals indicates that interactions are occurring in compact groups, but a blue color in one index alone does not require that these ellipticals are recent products of the merger of two spirals. The authors demonstrate how optical spectroscopy in the blue may distinguish between a true spiral + spiral merger and the swallowing of a gas-rich system by an already formed elliptical. The authors also show that the sum of the luminosity of the galaxies in each group is consistent with the hypothesis that the final stage in the evolution of compact group is an elliptical galaxy.

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

BLUE STRAGGLERS IN GLOBULAR CLUSTER 47 TUCANAE

NASA Technical Reports Server (NTRS)

2002-01-01

The core of globular cluster 47 Tucanae is home to many blue stragglers, rejuvenated stars that glow with the blue light of young stars. A ground-based telescope image (on the left) shows the entire crowded core of 47 Tucanae, located 15,000 light-years away in the constellation Tucana. Peering into the heart of the globular cluster's bright core, the Hubble Space Telescope's Wide Field and Planetary Camera 2 separated the dense clump of stars into many individual stars (image on right). Some of these stars shine with the light of old stars; others with the blue light of blue stragglers. The yellow circles in the Hubble telescope image highlight several of the cluster's blue stragglers. Analysis for this observation centered on one massive blue straggler. Astronomers theorize that blue stragglers are formed either by the slow merger of stars in a double-star system or by the collision of two unrelated stars. For the blue straggler in 47 Tucanae, astronomers favor the slow merger scenario. This image is a 3-color composite of archival Hubble Wide Field and Planetary Camera 2 images in the ultraviolet (blue), blue (green), and violet (red) filters. Color tables were assigned and scaled so that the red giant stars appear orange, main-sequence stars are white/green, and blue stragglers are appropriately blue. The ultraviolet images were taken on Oct. 25, 1995, and the blue and violet images were taken on Sept. 1, 1995. Credit: Rex Saffer (Villanova University) and Dave Zurek (STScI), and NASA

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.

Deep Sky Diving with the ESO New Technology Telescope

NASA Astrophysics Data System (ADS)

1998-01-01

Technology Telescope. Many of the advanced technological concepts now incorporated into the VLT were first tested in the NTT. When this new facility entered into operation at La Silla in 1990, it represented a break-through in telescope technology and it has since then made many valuable contributions to front-line astronomical projects. Last year, the control and data flow system at the NTT was thoroughly refurbished to the high VLT standards and current observations with the NTT closely simulate the future operation of the VLT. The successful, early tests with the new operations system have been described in ESO Press Release 03/97. The NTT SUSI Deep Field With the possibility to test already now observing procedures which will become standard for the operation of the VLT, a group of astronomers [1] was granted NTT time for observations of Faint Galaxies in an Ultra-Deep Multicolour SUSI field . This is a programme aimed at the study of the distribution of faint galaxies in the field and of gravitational lensing effects (cosmic mirages and deformation of images of distant galaxies caused by the gravitational field of intervening matter). SUSI (SUperb Seeing Imager) is a high-resolution CCD-camera at the NTT that is particularly efficient under excellent sky conditions. The observations were fully defined in advance and were carried out in service mode from February to April 1997 with flexible scheduling by a team of dedicated ESO astronomers (the NTT team). Only in this way was it possible to obtain the exposures under optimal atmospheric conditions, i.e. `photometric' sky and little atmospheric turbulence (seeing better than 1 arcsec). A total of 122 CCD frames were obtained in four colours (blue, green-yellow, red and near-infrared) with a total exposure time of no less than 31.5 hours. The frames cover a 2.3 x 2.3 arcmin `empty' sky field centered south of the high-redshift quasar QSO BR 1202-0725 (z=4.7), located just south of the celestial equator. ESO PR Photo 01a/98

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".

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.

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.

Blue nevus-like and blue nevus-associated melanoma: a comprehensive review of the literature.

PubMed

Borgenvik, Thore L; Karlsvik, Tina M; Ray, Saikat; Fawzy, Monica; James, Nick

2017-05-01

Malignant blue nevus, blue nevus-associated melanoma and blue nevus-like melanoma are all terms used to describe malignant melanomas arising from, in association with, or resembling blue nevi. This review is aimed at summarizing the available literature to reduce the confusion surrounding this rare malignancy, and aid the surgeon in choosing further diagnostic or therapeutic measures. We conducted a search of Medline, Embase, Science Direct, Scopus and the Cochrane Library for all full text articles published in English that reported on a malignant melanoma arising from, in association with, or resembling a blue nevus. We identified 91 cases that fit the criteria above. The mean age at diagnosis was 45 years, with a slight male predominance (males: 48; females: 43). Metastatic cases were reported in 55% (n = 50), of which 16 were metastatic at the time of diagnosis, 16 developed metastases within the first year and 18 within 5 years of initial diagnosis. The mean Breslow thickness was 6.8 mm at the time of diagnosis (n = 39). The histological criteria for diagnosing this malignancy are very poorly defined, and may contribute to the substantial confusion surrounding the terminology. There is no consensus on which prognostic indicators predictive of outcome in 'conventional' malignant melanoma are applicable to blue nevus-like melanoma/blue nevus-associated melanoma. However, two larger case series have demonstrated a significant association between Breslow thickness (or largest tumour dimension when non-epidermal) and recurrence-free survival, as well as rate of local recurrence, but larger studies are needed to confirm this. © 2017 Royal Australasian College of Surgeons.

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.

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

NASA Astrophysics Data System (ADS)

2009-09-01

The first of three images of ESO's GigaGalaxy Zoom project - a new magnificent 800-million-pixel panorama of the entire sky as seen from ESO's observing sites in Chile - has just been released online. The project allows stargazers to explore and experience the Universe as it is seen with the unaided eye from the darkest and best viewing locations in the world. This 360-degree panoramic image, covering the entire celestial sphere, reveals the cosmic landscape that surrounds our tiny blue planet. This gorgeous starscape serves as the first of three extremely high-resolution images featured in the GigaGalaxy Zoom project, launched by ESO within the framework of the International Year of Astronomy 2009 (IYA2009). GigaGalaxy Zoom features a web tool that allows users to take a breathtaking dive into our Milky Way. With this tool users can learn more about many different and exciting objects in the image, such as multicoloured nebulae and exploding stars, just by clicking on them. In this way, the project seeks to link the sky we can all see with the deep, "hidden" cosmos that astronomers study on a daily basis. The wonderful quality of the images is a testament to the splendour of the night sky at ESO's sites in Chile, which are the most productive astronomical observatories in the world. The plane of our Milky Way Galaxy, which we see edge-on from our perspective on Earth, cuts a luminous swath across the image. The projection used in GigaGalaxy Zoom place the viewer in front of our Galaxy with the Galactic Plane running horizontally through the image - almost as if we were looking at the Milky Way from the outside. From this vantage point, the general components of our spiral galaxy come clearly into view, including its disc, marbled with both dark and glowing nebulae, which harbours bright, young stars, as well as the Galaxy's central bulge and its satellite galaxies. The painstaking production of this image came about as a collaboration between ESO, the renowned

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.

The spectrum of dermatoscopic patterns in blue nevi.

PubMed

Di Cesare, Antonella; Sera, Francesco; Gulia, Andrea; Coletti, Gino; Micantonio, Tamara; Fargnoli, Maria Concetta; Peris, Ketty

2012-08-01

Blue nevi are congenital or acquired, dermal dendritic melanocytic proliferations that can simulate melanocytic and nonmelanocytic lesions including melanoma, cutaneous metastasis of melanoma, Spitz/Reed nevi, and basal cell carcinoma. We sought to investigate global and local dermatoscopic patterns of blue nevi compared with melanomas and basal cell carcinomas. We retrospectively analyzed global and local features in 95 dermatoscopic images of blue nevi and in 190 melanomas and basal cell carcinomas that were selected as control lesions on the basis of similar pigmentation. Lesion pigmentation was classified as monochromatic, dichromatic, or multichromatic. A global pattern characterized by homogeneous pigmentation was observed in all of 95 (100%) blue nevi. Eighty of 95 (84.2%) blue nevi presented a homogeneous pattern consisting of one color (blue, black, or brown) or two colors (blue-brown, blue-gray, or blue-black). Fifteen of 95 (15.8%) blue nevi had a multichromatic (blue, gray, black, brown, and/or red) pigmentation. In all, 47 of 95 (49.5%) blue nevi were characterized by pigmentation in the absence of pigment network or any other local dermatoscopic features. And 48 of 95 (50.5%) blue nevi showed local dermatoscopic patterns including whitish scarlike depigmentation, dots/globules, vascular pattern, streaks, and networklike pattern. The study was retrospective and involved only Caucasian people of Italian origin. The characteristic feature of blue nevi is a homogeneous pigmentation that is blue, blue-gray, blue-brown, or blue-black. We showed that a wide spectrum of local dermatoscopic features (whitish scarlike depigmentation, dots/globules, peripheral streaks or vessels) may also be present. In such cases, clinical and dermatoscopic distinction from melanoma or nonmelanocytic lesions may be difficult or impossible, and surgical excision is necessary. Copyright © 2011 American Academy of Dermatology, Inc. Published by Mosby, Inc. All rights reserved.

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".

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.

Mira Soars Through the Sky

NASA Technical Reports Server (NTRS)

2007-01-01

[figure removed for brevity, see original site] [figure removed for brevity, see original site] Figure 1Figure 2

New ultraviolet images from NASA's Galaxy Evolution Explorer shows a speeding star that is leaving an enormous trail of 'seeds' for new solar systems. The star, named Mira (pronounced my-rah) after the latin word for 'wonderful,' is shedding material that will be recycled into new stars, planets and possibly even life as it hurls through our galaxy.

In figure 1, the upper panel shows Mira's full, comet-like tail as seen only in shorter, or 'far' ultraviolet wavelengths, while the lower panel is a combined view showing both far and longer, or 'near' ultraviolet wavelengths. The close-up picture at bottom gives a better look at Mira itself, which appears as a pinkish dot, and is moving from left to right in this view. Shed material appears in light blue. The dots in the picture are stars and distant galaxies. The large blue dot on the left side of the upper panel, and the large yellow dot in the lower panel, are both stars that are closer to us than Mira.

The Galaxy Evolution Explorer discovered the strange tail during part of its routine survey of the entire sky at ultraviolet wavelengths. When astronomers first saw the picture, they were shocked because Mira has been studied for over 400 years yet nothing like this has ever been documented before.

Mira's comet-like tail stretches a startling 13 light-years across the sky. For comparison, the nearest star to our sun, Proxima Centauri, is only about 4 light-years away. Mira's tail also tells a tale of its history -- the material making it up has been slowly blown off over time, with the oldest material at the end of the tail being released about 30,000 years ago (figure 2).

Mira is a highly evolved, 'red giant' star near the end of its life. Technically, it is called an asymptotic giant branch star. It is red in color and bloated; for example, if a red giant were to replace

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.

Experiencing Blues at the Crossroads: A Place-Based Method for Teaching the Geography of Blues Culture

ERIC Educational Resources Information Center

Strait, John

2012-01-01

This article offers a pedagogical module that explores the geography of blues culture across the Mississippi Delta. By focusing on blues culture, rather than simply blues music itself, this project provides a forum for understanding the broader geographical conditions from which this musical form emerged. This module utilizes place-based…

Metastatic malignant blue nevus: a case report.

PubMed

Ozgür, F; Akyürek, M; Kayikçioğlu, A; Barişta, I; Gököz, A

1997-10-01

This report presents a 63-year-old Caucasian woman with a malignant blue nevus, which is an extremely rare form of melanoma originating from or associated with a preexisting blue nevus. The background blue nevus on the left upper arm, which had been present for 5 to 6 years, increased in size and darkened in color for 3 months prior to histological diagnosis of malignant blue nevus. Although the tumor looked much like a nodular melanoma clinically, the diagnosis of malignant blue nevus was established histologically. The patient had a poor outcome due to metastatic spread of the tumor to the visceral organs 1 year following the initial excision of the tumor. To distinguish this rare tumor from other melanocytic lesions, strict histological criteria are needed to make the diagnosis of malignant blue nevus. Differential diagnosis includes cellular blue nevus, atypical cellular blue nevus, primary malignant melanoma, and metastatic melanoma to the dermis. Malignant blue nevus is most commonly seen on the scalp. The tumor has an aggressive behavior and metastasizes in the majority of patients. This paper describes the second reported case of malignant blue nevus involving the upper arm. Clinical and histological features of this uncommon tumor are presented, along with a review of the literature.