KEYWORDS: Gamma radiation, Space operations, Space telescopes, Sensors, Observatories, Crystals, Particles, Calibration, Telescopes, Monte Carlo methods
The Fermi Gamma-ray Space Telescope, launched in June 2008, is an observatory designed to survey the high-energy gamma-ray sky. The primary instrument, the Large Area Telescope (LAT), provides observations from 20 MeV to greater than 300 GeV. A second instrument, the Gamma-ray Burst Monitor (GBM), provides observations of transients from less than 10 keV to 40 MeV. We describe the design and performance of the instruments and their subsystems, the spacecraft and the ground system.
The Gamma-ray Large Area Space Telescope (GLAST) is the next orbiting high-energy gamma-ray mission, scheduled for launch by NASA in 2006. The GLAST Observatory will have two scientific instruments: (1) the Large Area Telescope (LAT), an imaging, wide field-of-view telescope sensitive to radiation over the energy range from ~20 MeV to more than 300 GeV, and (2) the GLAST Burst Monitor (GBM), sensitive to transient bursts from 10 keV to 25 MeV. The GBM is described elsewhere in this proceedings by Lichti, et al. The LAT, a pair-conversion telescope, is being developed by an international collaboration from the United States, France, Italy, Japan, and Sweden. It will have sensitivity more than 40 times better than that of EGRET. In this paper the LAT instrument, its expected performance, and the current state of its development are described.
KEYWORDS: Sensors, Gamma radiation, Silicon, Particles, Spatial resolution, Space telescopes, Photons, Telescopes, Monte Carlo methods, Solid state electronics
The gamma-ray large area space telescope (GLAST) is a proposed next-generation high-energy gamma-ray telescope for studying emission from astrophysical sources in the 10 MeV to 300 GeV energy range. GLAST is currently under study as a NASA new mission concept in astrophysics. The primary scientific targets for the GLAST mission include active galactic nuclei, gamma-ray bursts, neutron stars, and the diffuse galactic and extragalactic high-energy radiation. GLAST relies on the unambiguous identification of incident gamma-rays by detection of the electron and positron that result from pair creation in a thin converter material. Measurement of the energy and direction of the electron- positron pair shower provides information about the energy and direction of the incident gamma-ray. The GLAST design utilizes modern solid-state particle detector technology and recently developed space-qualified computers. Because of the technical approach, the telescope design can be easily optimized to a range of sizes. For example, accommodation of GLAST within a Delta II size launch system results in an instrument with capabilities well beyond those of the highly successful EGRET currently operating on the Compton Observatory; namely, a broader energy range, larger effective area, wider field of view, and single-photon angular resolution 2 to 5 times more precise than EGRET's resolution. GLAST will have an effective area of 8000 cm2 above 300 MeV, a field of view of 2.6 sr, and single photon angular resolution (rms projected) of 0.3 degrees at 1 GeV, approaching 0.03 degrees above 20 GeV.
Kent Wood, Gilbert Fritz, Paul Hertz, W. Neil Johnson, Michael Kowalski, Michael Lovellette, Michael Wolff, Daryl Yentis, Edward Bloom, L. Cominsky, K. Fairfield, G. Godfrey, J. Hanson, A. Lee, Peter Michelson, R. Taylor, H. Wen
The Unconventional Stellar Aspect (USA) experiment on the Advanced Research and Global Observations Satellite (ARGOS) of the Space Test Program is a low-cost, quick, yet scientifically ambitious X-ray timing experiment. The research program emphasizes observing neutron stars and black holes for extended periods with sub-millisecond timing resolution. The scientific program is achieved using hardware whose key features are large collecting area (2000 cm2), energy response extending as low as 1 keV, long accumulated observing times (1 month), high time resolution (1 microsecond(s) ), absolute time-tagging (also to 1 microsecond(s) ) achieved using a GPS receiver, sustained high data rates (40 kbps at all times supplemented by 128 kbps as needed), and flexibility in data handling by using a solid state recorder and a radiation- hardened 20 MIPS 32-bit onboard computer to provide onboard processing.
Conference Committee Involvement (1)
X-ray and Gamma-ray Telescopes and Instruments for Astronomy
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