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  • 1
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    SAS-2 observations of gamma rays from the galactic plane (1974)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: Preliminary data are given for the SAS-2 high energy galactic gamma ray observation. These data include both latitude and longitude distributions. The longitude distribution shows a high density region. The latitude distributions toward the center and the anti-center are markedly different, the former showing a two-component structure of half-widths of approximately 3 and 6 deg. The energy spectrum in the range 35 to 200 MeV is hard, consistent with cosmic ray interactions with interstellar matter, including neutral pions decay and emission from energetic electron interactions. The data is consistent with an interpretation in terms of the confinement of the cosmic rays in the spiral arms.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: ESRO The Context and Status of Gamma Ray Astronomy; p 201-204
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  • 2
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    A Systematic Search for Short-term Variability of EGRET Sources (2000)
    In:  CASI
    Details
    Publication Date: 2013-08-29
    Description: The 3rd EGRET Catalog of High-energy Gamma-ray Sources contains 170 unidentified sources, and there is great interest in the nature of these sources. One means of determining source class is the study of flux variability on time scales of days; pulsars are believed to be stable on these time scales while blazers are known to be highly variable. In addition, previous work has demonstrated that 3EG J0241-6103 and 3EG J1837-0606 are candidates for a new gamma-ray source class. These sources near the Galactic plane display transient behavior but cannot be associated with any known blazers. Although, many instances of flaring AGN have been reported, the EGRET database has not been systematically searched for occurrences of short-timescale (approximately 1 day) variability. These considerations have led us to conduct a systematic search for short-term variability in EGRET data, covering all viewing periods through proposal cycle 4. Six 3EG catalog sources are reported here to display variability on short time scales; four of them are unidentified. In addition, three non-catalog variable sources are discussed.
    Keywords: Astrophysics
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  • 3
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    GLAST Large Area Telescope Multiwavelength Planning (2007)
    In:  CASI
    Details
    Publication Date: 2018-06-06
    Description: Gamma-ray astrophysics depends in many ways on multiwavelength studies. The Gamma-ray Large Area Space Telescope (GLAST) Large Area Telescope (LAT) Collaboration has started multiwavelength planning well before the scheduled 2007 launch of the observatory. Some of the high-priority multiwavelength needs include: (1) availability of contemporaneous radio and X-ray timing of pulsars; (2) expansion of blazar catalogs, including redshift measurements; (3) improved observations of molecular clouds, especially at high galactic latitudes; (4) simultaneous broad-spectrum blazar monitoring; (5) characterization of gamma-ray transients, including gamma ray bursts; (6) radio, optical, X-ray and TeV counterpart searches for reliable and effective sources identification and characterization. Several of these activities are needed to be in place before launch.
    Keywords: Astrophysics
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  • 4
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    Future Facilities for Gamma-Ray Pulsar Studies (2003)
    In:  CASI
    Details
    Publication Date: 2018-06-06
    Description: Pulsars seen at gamma-ray energies offer insight into particle acceleration to very high energies, along with information about the geometry and interaction processes in the magnetospheres of these rotating neutron stars. During the next decade, a number of new gamma-ray facilities will become available for pulsar studies. This brief review describes the motivation for gamma-ray pulsar studies, the opportunities for such studies, and some specific discussion of the capabilities of the Gamma-ray Large Area Space Telescope (GLAST) Large Area Telescope (LAT) for pulsar measurements.
    Keywords: Astrophysics
    Type: Young Neutron Stars and Their Environments: IAU Symposium; Volume 218; 1-6
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  • 5
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    An Intriguing Convex Break in the EGRET SED of Mrk 421 (2007)
    In:  CASI
    Details
    Publication Date: 2018-06-06
    Description: Based upon analysis of the entire EGRET data from Mrk 421, it is found that the time-averaged spectra are inconsistent with the predictions of current theoretical models that have had success in describing simultaneous X-ray/TeV observations, and suggest additional components in the GeV band, as well as complex time variability. Current theoretical pictures explain the GeV emission as comptonization of the synchrotron photons in the jet, and predict hard spectra that should join smoothly with the TeV emission. Our analysis shows that the situation is more complex. The spectrum ranges from hard to soft during individual epochs, and shows a convext break in the aggregated data. We also present the mission-averaged EGRET spectrum for PKS 2155-304, which shows a similar (but not as pronounced) convex curvature. We discuss a series of possible explanations for the 10(exp 22) - 10(exp 23) HZ declining part of the EGRET nu F(sub nu), spectrum for Mrk 421, and suggest that it is synchrotron emission from the high energy tail of the electron population that produces the X-rays during the highest X-ray states. Such multi-MeV photons are produced by electrons accelerated close to the limit of diffusive shock acceleration. Simultaneous GLAST and X-ray observations of high X-ray states will address the issue of the convex curvature in the future.
    Keywords: Astrophysics
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  • 6
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    The Highest-Energy Photons Seen by the Energetic Gamma-Ray Experiment Telescope (EGRET) on the Compton Gamma Ray Observatory (2005)
    In:  CASI
    Details
    Publication Date: 2018-06-06
    Description: During its nine-year lifetime, the Energetic Gamma Ray Experiment Telescope (EGBET) on the Compton Gamma Ray Observatory (CGRO) detected 1506 cosmic photons with measured energy E〉10 GeV. Of this number, 187 are found within a 1 deg of sources that are listed in the Third EGRET Catalog and were included in determining the detection likelihood, flux, and spectra of those sources. In particular, five detected EGRET pulsars are found to have events above 10 GeV, and together they account for 37 events. A pulsar not included in the Third EGRET Catalog has 2 events, both with the same phase and in one peak of the lower-energy gamma-ray light-curve. Most of the remaining 1319 events appear to be diffuse Galactic and extragalactic radiation based on the similarity of the their spatial and energy distributions with the diffuse model and in the E〉100, MeV emission. No significant time clustering which would suggest a burst was detected.
    Keywords: Astrophysics
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  • 7
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    Balloon-borne scanning spectrometer system for atmospheric extinction studies in the 350-1100 nm spectral region (1982)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: A scanning spectrometer system which is capable of being flown in high-altitude balloon studies of the earth's atmosphere is presented. The instrument is small, has a large operative wavelength range of 350-1100 nm, high data density, and real-time data telemetry to ground. A computer software package is used to provide a real-time monitor of balloon gondola and instrument performance, with the software reliability enhanced by proof of correctness techniques and exhibiting the high degree of reliability necessary for the monitoring system.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Review of Scientific Instruments; 53; Mar. 198
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  • 8
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    Gravity gradient preliminary investigations on exhibit ''A'' Final report (1969)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Quartz microbalance gravity gradiometer performance tests
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA-CR-101867 , GO-REPT-9
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  • 9
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    GLAST Large Area Telescope Multiwavelength Planning (2006)
    In:  Other Sources
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    Publication Date: 2019-07-18
    Description: Because gamma-ray astrophysics depends in many ways on multiwavelength studies, the GLAST Large Area Telescope (LAT) Collaboration has started multiwavelength planning well before the scheduled 2007 launch of the observatory. Some of the high-priority needs include: (1) radio and X-ray timing of pulsars; (2) expansion of blazar catalogs, including redshift measurements (3) improved observations of molecular clouds, especially at high galactic latitudes; (4) simultaneous broad-spectrum blazar flare measurements; (5) characterization of gamma-ray transients, including gamma ray bursts; (6) radio, optical, X-ray and TeV counterpart searches for unidentified gamma-ray sources. Work on the first three of these activities is needed before launch. The GLAST Large Area Telescope is an international effort, with U.S. funding provided by the Department of Energy and NASA.
    Keywords: Astrophysics
    Type: American Astronomical Society 207th Meeting; Jan 08, 2006 - Jan 12, 2006; Washington, DC; United States
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  • 10
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    GUST LAT Multiwavelength Planning (2004)
    In:  Other Sources
    Details
    Publication Date: 2019-07-18
    Description: Because gamma-ray astrophysics profits in powerful ways from multi-wavelength studies, the GLAST Large Area Telescope (LAT) Collaboration has started multiwavelength planning well before the scheduled 2007 launch. Many aspects of this program are of direct interest to observers using VERITAS and other atmospheric Cerenkov telescopes, whose capabilities complement those of GLAST. This talk with describe some of the current developmental concepts for GLAST LAT multiwavelength work, including release of data for transient sources, nearly-continuous monitoring of selected time-variable sources, pulsar timing, follow-on observations for source identification, coordinated blazar campaigns, and cross-calibration with other high-energy telescopes. Although few details are firm at this stage of preparation for GLAST, the LAT Collaboration looks forward to cooperation with a broad cross-section of the multiwave-length community. The GLAST Large Area Telescope is an international effort, with U.S. funding provided by the Department of Energy and NASA.
    Keywords: Astrophysics
    Type: High Energy Astrophysics Meeting; Sep 07, 2004 - Sep 11, 2004; New Orleans, LA; United States
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