摘要:

The Burst Alert Telescope (BAT) on Swift has two main types of “rate” triggers: short and long. Short trigger time scales range from 4ms to 64ms, while long triggers are 64ms to ≈ 16 seconds. While both short and long trigger have criteria with one background sample (traditional “one‐sided” triggers), the long triggers can also have criteria with two background samples (“bracketed” triggers) which remove trends in the background. Both long and short triggers can select energy ranges of 15–25, 15–50, 25–100 and 50–350 KeV. There are more than 180 short triggering criteria and approximately 500 long triggering criteria used to detect gamma ray bursts. To fully utilize these criteria, the thresholds must be set correctly. The optimum thresholds are determined by a tradeoff between avoiding false triggers and capturing as many bursts as possible. We use realistic simulated orbital variations, which are the prime cause of false triggers. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1810931

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

The Burst Alert Telescope (BAT), a large coded aperture instrument with a wide field‐of‐view (FOV), provides the gamma‐ray burst triggers and locations for the Swift Gamma‐Ray Burst Explorer. In addition to providing this imaging information, BAT will perform a 15 keV – 150 keV all‐sky hard x‐ray survey based on the serendipitous pointings resulting from the study of gamma‐ray bursts, and will also monitor the sky for transient hard x‐ray sources. For BAT to provide spectral and photometric information for the gamma‐ray bursts, the transient sources and the all‐sky survey, the BAT instrument response must be determined to an increasingly greater accuracy. This paper describes the spectral models and the ground calibration experiments used to determine the BAT response to an accuracy suitable for gamma‐ray burst studies. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1810932

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

We describe the Energetic X‐ray Imaging Survey Telescope EXIST, designed to carry out a sensitive all‐sky survey in the 10 keV – 600 keV band. The primary goal of EXIST is to find black holes in the local and distant universe. EXIST also traces cosmic star formation via gamma‐ray bursts and gamma‐ray lines from radioactive elements ejected by supernovae and novae. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1810933

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

Theoretical models, especially within the framework of Quantum Gravity, allow for the possibility of a velocity dispersion effect for photons of different energies traveling cosmological distances. Due to their fine‐scale time structure and their broad band emission, that is accurately modeled in this work, Gamma Ray Bursts could be good probes of such effect. GLAST will detect several GRBs per year at high energy where the effect could be detectable. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1810934

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

The Gamma Ray Large Area Space Telescope (GLAST) mission is a followup to the successful EGRET experiment onboard the Compton Gamma Ray Observatory (CGRO). It will provide a high‐sensitivity survey of the sky in high‐energy &ggr;‐rays, and will perform detailed observations of persistent and transient sources. There are two experiments onboard the GLAST — the Large Area Telescope (LAT) and the GLAST Burst Monitor (GBM).The primary mission of the GBM instrument is to support the LAT in observing &ggr;‐ray bursts (GRBs) by providing low‐energy measurements with high time resolution and rapid burst locations over a large field‐of‐view (⩾ 8 sr). The GBM will complement the LAT measurements by observing GRBs in the energy range 10 keV to 30 MeV, the region of the spectral turnover in most GRBs. An important objective of the GBM is to compute the locations of GRB sources on‐board the spacecraft and quickly communicate them to the LAT and to the ground to allow rapid followup observations. This information may be used to re‐point the LAT towards particularly interesting burst sources that occurred outside its field‐of‐view.The GBM consists of 14 uncollimated scintillation detectors coupled to phototubes to measure &ggr;‐ray energies and time profiles. Two types of detectors are used to obtain spectral information over a wide energy range: 12 NaI(Tl) detectors (10 keV to 1 MeV), and 2 BGO detectors (150 keV to 30 MeV). The detectors are distributed around the GLAST spacecraft to provide a large, unobstructed field of view. The 12 NaI(Tl) detectors are mounted with different orientations for use in locating GRB sources. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1810935

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

The GLAST Burst Monitor (GBM) will detect and localize bursts for the GLAST mission, and provide the spectral and temporal context in the traditional 10 keV to 25 MeV band for the high energy observations by the Large Area Telescope (LAT). The GBM will use traditional rate triggers in up to three energy bands, and on a variety of timescales between 16 ms and 16 s. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1810936

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

Analyzing data from GLAST’s Large Area Telescope (LAT) will require sophisticated techniques. The PSF and effective area are functions of both photon energy and the position in the field‐of‐view. During most of the mission the observatory will survey the sky continuously, and thus, the LAT will detect each count from a source at a different detector orientation; each count requires its own response function! The likelihood as a function of celestial position and photon energy will be the foundation of the standard analysis techniques. However, the 20 MeV–300 GeV emission at the time of the ∼ 100 keV burst emission (timescale of ∼ 10 s) can be isolated and analyzed because essentially no non‐burst counts are expected within a PSF radius of the burst location during the burst. Both binned and unbinned (in energy) spectral fitting will be possible. Longer timescale afterglow emission will require the likelihood analysis that will be used for persistent sources. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1810937

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

SuperAGILE is the hard X‐ray (10–40 keV) imager for the gamma‐ray mission AGILE, currently scheduled for launch in mid‐2005. It is based on 4 Si‐microstrip detectors, with a total geometric area of 1444 cm2(max effective about 300 cm2), equipped with one‐dimensional coded masks. The 4 detectors are perpendicularly oriented, in order to provide pairs of orthogonal one‐dimensional images of the X‐ray sky. The field of view of each 1‐D detector is 107 °×68°, at zero response, with an overlap in the central 68°×68° area. The angular resolution on axis is 6 arcmin (pixel size). We present here the current status of the hardware development and the scientific potential for GRBs, for which an onboard trigger and imaging system will allow distributing locations through a fast communication telemetry link from AGILE to the ground. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1810938

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

AGILE is an ASI (Italian Space Agency) Small Space Mission for high energy astrophysics in the range 30 MeV – 50 GeV. The AGILE satellite is currently in the C phase and is planned to be launched in 2005. The Payload shall consist of a Tungsten‐Silicon Tracker, a CsI Minicalorimeter, an anticoincidence system and a X‐Ray detector sensitive in the 10–40 KeV range. The purpose of the Minicalorimeter (MCAL) is twofold. It shall work in conjunction with the Tracker in order to evaluate the energy of the interacting photons, and it shall operate autonomously in the energy range 250KeV–250 MeV for detection of transients and gamma ray burst events and for the measurement of gamma ray background fluctuations. We present the architecture of the Test Equipment we have designed and developed in order to test and verify the MCAL Simplified Electrical Model prototype which has been manufactured in order to validate the design of the MCAL Proto Flight Model. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1810939

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

Gamma Ray Bursts (GRBs) present different prompt and delayed emission properties which might suggest a possible taxonomy. Nonetheless, the existence of different classes could be the combined effect of different intrinsic and/or observational conditions. The latter, in particular, are related to the instrumental capabilities. For this reason, we studied the instrumental sensitivity of the AGILE satellite as a function of the spectral properties of GRBs. AGILE will be able to detect most of the bright‐long bursts and its two detectors, with their independent trigger algorithms, compensate each other in detecting soft and high energy GRBs. Moreover, AGILE will possibly give a major contribution in the study of very energetic bursts with typical peak energies above ∼ 1 MeV. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1810940

出版商:AIP    

年代:1904

数据来源: AIP