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  • 1
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    A search for primeval galaxies (1991)
    In:  Other Sources
    Details
    Publication Date: 2011-08-24
    Description: We are conducting a search for emission-line objects at large redshifts, ostensibly young and forming galaxies. Our method is to search for strong line emission, in particular Ly-alpha, using two techniques: a direct, narrow-band imaging search using a Fabry-Perot interferometer; and a serendipitous long-slit spectroscopic search. Assuming that none of the faint candidates found so far are actually primeval galaxies, we can set the strongest limits to date on the surface density of Ly-alpha-luminous primeval galaxies on the sky. Some of the faint emission line galaxies detected in our survey at z roughly 0.5 - 1 may be representative of the faint blue galaxy population detected in deep continuum imaging surveys.
    Keywords: ASTRONOMY
    Type: In: The space distribution of quasars; Proceedings of the Workshop, Victoria, Canada, June 3-5, 1991 (A93-28776 10-90); p. 354-357.
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  • 2
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    SAS 2 observations of the earth albedo gamma radiation above 35 MeV (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: The earth albedo gamma radiation above 35 MeV in the equatorial region is investigated using observations from the second Small Astronomy Satellite. The zenith angle distribution of the gamma radiation has a peak toward the horizon which is about an order of magnitude more intense than the radiation coming from the nadir, and nearly two orders of magnitude more intense than the gamma radiation from most parts of the sky. The gamma radiation originating from the western horizon is a factor of four more intense than the radiation from the eastern horizon and a factor of three more intense than that from the northern and southern directions. This reflects the geomagnetic effects on the incident cosmic rays whose interactions produce the albedo gamma rays. The variation of the upcoming gamma ray intensity with vertical cutoff rigidity is consistent with the empirical relationship found by Gur'yan et al. (1979).
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research; 86; Mar. 1
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  • 3
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    Spectrophotometry of Epsilon Aur, 3295-8880 A (1985)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Spectrophotometric scans were obtained at 8 A resolution from 3295 to 8880 A on twenty nights before, during, and after the recent eclipse of epsilon Aurigae, beginning with a pre-eclipse observation on 5 March 1982 U.T. The observations were reduced to absolute flux using the standard stars 109 Vir or xi(2) Ceti. The data confirm that the eclipse is essentially gray over the entire visible spectrum, as others have noted from broadband photometry. High resolution echellograms (450 to 6700 A) made through mid-eclipse and the scans show changes in the equivalent widths of H alpha, Na D, and O I as large as a factor of two.
    Keywords: ASTRONOMY
    Type: NASA, Washington The 1982-1984 Eclipse of Epsilon Aurigae; p 79
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  • 4
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    Studying the High Energy Gamma Ray Sky with Gamma Ray Large Area Space Telescope (GLAST) (1998)
    In:  CASI
    Details
    Publication Date: 2013-08-29
    Description: Building on the success of the Energetic Gamma Ray Experiment Telescope (EGRET) on the Compton Gamma Ray Observatory, the Gamma Ray Large Area Space Telescope (GLAST) will make a major step in the study of such subjects as blazars, gamma Ray bursts, the search for dark matter, supernova remnants, pulsars, diffuse radiation, and unidentified high energy sources. The instrument will be built on new and mature detector technologies such as silicon strip detectors, low-power low-noise LSI, and a multilevel data acquisition system. GLAST is in the research and development phase, and one full tower (of 25 total) is now being built in collaborating institutes. The prototype tower will be tested thoroughly at Stanford Linear Accelerator Center (SLAC) in the fall of 1999.
    Keywords: Astronomy
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  • 5
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    Gamma Ray Large Area Space Telescope (GLAST) Balloon Flight Engineering Model: Overview (2001)
    In:  CASI
    Details
    Publication Date: 2013-08-29
    Description: The Gamma Ray Large Area Space Telescope (GLAST) Large Area Telescope (LAT) is a pair-production high-energy (greater than 20 MeV) gamma-ray telescope being built by an international partnership of astrophysicists and particle physicists for a satellite launch in 2006, designed to study a wide variety of high-energy astrophysical phenomena. As part of the development effort, the collaboration has built a Balloon Flight Engineering Model (BFEM) for flight on a high-altitude scientific balloon. The BFEM is approximately the size of one of the 16 GLAST-LAT towers and contains all the components of the full instrument: plastic scintillator anticoincidence system (ACD), high-Z foil/Si strip pair-conversion tracker (TKR), CsI hodoscopic calorimeter (CAL), triggering and data acquisition electronics (DAQ), commanding system, power distribution, telemetry, real-time data display, and ground data processing system. The principal goal of the balloon flight was to demonstrate the performance of this instrument configuration under conditions similar to those expected in orbit. Results from a balloon flight from Palestine, Texas, on August 4, 2001, show that the BFEM successfully obtained gamma-ray data in this high-background environment.
    Keywords: Astronomy
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  • 6
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    Performance of the Anti-Coincidence Detector on the GLAST Large Area Telescope (2007)
    In:  CASI
    Details
    Publication Date: 2018-06-06
    Description: The Anti-Coincidence Detector (ACD), the outermost detector layer in the Gamma-ray Large Area Space Telescope (GLAST) Large Area Telescope (LAT), is designed to detect and veto incident cosmic ray charged particles, which outnumber cosmic gamma rays by 3-4 orders of magnitude. The challenge in ACD design is that it must have high (0.9997) detection efficiency for singly-charged relativistic particles, but must also have a low probability for self-veto of high-energy gammas by backplash radiation from interactions in the LAT calorimeter. Simulations and tests demonstrate that the ACD meete its design requirements. The performance of the ACD has remained stable thrugh stand-alone environmental testing, shipment across the U.S. installation onto the LAT, shipment back across the U.S., LAT environmental testing, and shipment to Arizona. As part of the fully-assembled GLAST observatory, the ACD is being readied for final testing before launch.
    Keywords: Astronomy
    Type: AIP Conference Proceedings (The First GLAST Symposium) (ISSN 0094-243X); Volume 921; 588-589
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  • 7
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    The Anti-Coincidence Detector for the GLAST Large Area Telescope (2007)
    In:  CASI
    Details
    Publication Date: 2018-08-10
    Description: This paper describes the design, fabrication and testing of the Anti-Coincidence Detector (ACD) for the Gamma-ray Large Area Space Telescope (GLAST) Large Area Telescope (LAT). The ACD is LAT's first-level defense against the charged cosmic ray background that outnumbers the gamma rays by 3-5 orders of magnitude. The ACD covers the top and 4 sides of the LAT tracking detector, requiring a total active area of -8.3 square meters. The ACD detector utilizes plastic scintillator tiles with wave-length shifting fiber readout. In order to suppress self-veto by shower particles at high gamma-ray energies, the ACD is segmented into 89 tiles of different sizes. The overall ACD efficiency for detection of singly charged relativistic particles entering the tracking detector from the top or sides of the LAT exceeds the required 0.9997.
    Keywords: Astronomy
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  • 8
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    High Efficiency Plastic Scintillator Detector with Wave-Length Shifting Fiber Readout for the GLAST Large Area Telescope (2007)
    In:  CASI
    Details
    Publication Date: 2018-08-10
    Description: This paper describes the design and performance studies of the scintillator tile detectors for the Anti-Coincidence Detector (ACD) of the Large Area Telescope (LAT) on the Gamma ray Large Area Space Telescope (GLAST), scheduled for launch in early 2008. The scintillator tile detectors utilize wavelength shifting fibers and have dual photomultiplier tube (PMT) readout. The design requires highly efficient and uniform detection of singly charged relativistic particles over the tile area and must meet all requirements for a launch, as well as operation in a space environment. We present here the design of three basic types of tiles used in the ACD, ranging in size from approx.450 sq cm to approx.2500 sq cm, all 1 cm thick, with different shapes, and with photoelectron yield of approx. 20 photoelectrons per minimum ionizing particle (mip) at normal tile incidence, uniform over the tile area. Some tiles require flexible clear fiber cables up to 1.5 m long to deliver scintillator light to remotely located PMT.
    Keywords: Astronomy
    Type: Meeting held on Oct. 1-5, 2007 in Moscow, Russia. To appear in the Journal of Nuclear Instruments and Methods, Elsevier
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  • 9
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    Photoelectric photometry of asteroid 69 Hesperia (1985)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: UBV photometric observations of the M asteroid 69 Hesperia, obtained using single-channel photometers on the 31-in. and 42-in. reflectors at Lowell Observatory and on the 24-in. reflector at Mauna Kea Observatory during the apparition of August-November 1977, are reported. The data are presented in tables and graphs and analyzed. Findings presented include minimal temporal or phase-angle-dependent light-curve fluctuations, evidence for large-scale albedo variegation of a few percent, synodic rotation period 5.65537 + or - 0.00064 h, zero-phase color indices B-V = 0.68 mag and U-B = 0.24 mag, B-V phase reddening 0.003 mag/deg, and absolute zero-phase primary maximum magnitude V = 7.04.
    Keywords: ASTRONOMY
    Type: Astronomy and Astrophysics Supplement Series (ISSN 0365-0138); 61; 291-297
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  • 10
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    The albedo of Uranus (1983)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: New absolute spectrophotometry of Uranus between 3295 A and 7676 A obtained at spectral resolutions of 4 A and 8 A during its 1981 apparition is reported and compared with previous observations by Younkin (1970) recorded during the 1961-1963 apparitions. Geometric albedos are calculated, and Bond albedos are estimated for both sets of data. An increase in brightness of about 14% and a color change occurred during the interval between the epochs of observation, consistent with the high north-polar haze reported by Price and Franz (1979) and the change in aspect of the planet. An upper limit to the internal heat source is estimated from energy balance considerations.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; vol. 266
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