摘要:

FiberGLAST is one of several instrument concepts being developed for possible inclusion as the primary Gamma-ray Large Area Space Telescope (GLAST) instrument. The predicted FiberGLAST effective area is more than 12,000 cm2for energies between 30 MeV and 300 GeV, with a field of view that is essentially flat from 0°–80°. The detector will achieve a sensitivity more than 10 times that of EGRET. We present results of simulations that illustrate the sensitivity of FiberGLAST for the detection of gamma-ray bursts. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1361626

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

The BeppoSAX Gamma Ray Burst Monitor (GRBM) is triggered any time a statistically significant counting excess is simultaneously revealed by at least two of its four independent detectors. Several spurious effects, including highly ionizing particles crossing two detectors, are recorded as onboard triggers. In fact, a large number of false triggers is detected, on the order of 10/day. A software code, based on an heuristic algorithm, was written to discriminate between real and false triggers. We present the results of the analysis on an homogeneous sample of GRBM triggers, thus providing an estimate of the efficiency of the GRB detection system consisting of the GRBM and the software. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1361627

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

A method to evaluate the capability to localize Gamma-Ray Burst (GRB) sources with the Gamma-Ray Burst Monitor (GRBM) onboard BeppoSAX is presented. The instrument is composed of four differently oriented detectors, so that their relative counting rates can be used to reconstruct the incoming direction of the GRB photons. The method involves the minimization of an energy- and direction-dependent&khgr;2-like variable related to the difference between the intensities observed by the four GRBM detectors and their expected values, as derived from the instrument’s response functions. The method is applied to a sample of GRBs simultaneously detected and localized by other experiments, in order to compare the achieved results with locations determined independently. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1361628

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

Preliminary results of a study aimed to the determination of the response function, in direction and energy, of the Gamma-Ray Burst Monitor (GRBM) onboard the BeppoSAX satellite are presented. The study has been carried out by means of Monte Carlo techniques, taking into account on-ground calibration before launch, and the Crab spectrum measured during the flight. The derived response matrix will be used to evaluate properties (e.g., direction, spectrum, fluence) of all Gamma-Ray Bursts detected with the GRBM. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1361629

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

The present gamma-ray burst (GRB) network consists of the Ulysses and the Near Earth Asteroid Rendezvous missions in deep space, with the BATSE experiment on Compton-GRO, the Konus experiment on GGS-Wind, and the BeppoSAX mission all near to the Earth. The NEAR spacecraft, built and launched without any GRB capability, was modified in flight to provide 1-second GR count rates, creating the first 3-cornered long-baseline IPN since the early 1990s. The arc-minute precision of this IPN was confirmed with the known locations of SGRs and GRB afterglows. After the Eros orbital insertion maneuver was postponed until February 2000, the NEAR spacecraft was placed in a low bit-rate, dormant mode, but was dedicated to GR data by command. Most events are now saved, although data recovery is necessarily delayed up to several days. Restoration to the active mode is expected in January 2000. Note: since the Huntsville Symposium, the first all-IPN alert to result in radio and/or optical afterglow observations followed GRB991208. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1361630

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

The GRB Coordinates Network (GCN) was designed to deliver locations of GRBs to instruments and observers in real-time (a few seconds)—while the burst is still bursting—so that they can make multi-band simultaneous follow-up observations. This goal has been realized with the optical detection of the burst counterpart for GRB990123 by the ROTSE instrument [1]. A brief review of the function and capabilities of the GCN system is given; the types of GRB location information available plus the distribution methods are described. Complementing the real-time location Notices, the GCN Circulars allow follow-up observers to rapidly share the results of their observations with the community. A status report on recent improvements to the GCN system and a list of future improvements is given. One of the key improvements will be the conversion of the semi-manual RBR LOCBURST locations into the fully automated LOCFAST Notices. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1361631

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

We present an update on our ongoing effort to establish a dedicated observation program with an automated 0.6 meter telescope system that can detect GRB optical signals from 30 s to many hours after the start of the burst. The Super-LOTIS telescope has a0.8°×0.8°field-of-view, is sensitive toV&hthinsp;17∼19objects, depending on the integration times, and will be placed at the Kitt Peak National Observatory. This paper presents technical aspects of this telescope and first results from initial operations at LLNL. Utilizing real-time coordinates from BATSE, BeppoSAX, XTE, IPN, HETE-2 and INTEGRAL, our LOTIS and SLOTIS systems will measure prompt GRB optical light curves that will enhance our understanding of GRBs. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1361632

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

An automated, wide-field, 1.3-m aperture optical telescope was recently commissioned at the U.S. Naval Observatory, Flagstaff Station. Employing a multifilter camera with six SITe2048×4096&hthinsp;CCDs,it has a field of view of approximately1.4°×1.0°with 0.6″ pixelization. It is capable of imaging atV=21&hthinsp;magwithS/N=10in less than 20 s of integration. While it will be employed primarily for astrometric observations, it is planned to be used also for GRB counterpart searches. The combination of automated operation, moderate aperture, large field of view, and small pixelization should allow for systematic and deeper searches than have previously been attempted, for example, of LOCBURST positions. Examination of GRB localizations that are not x-ray selected may reveal new counterpart properties. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1361633

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

TAROT-2 (Te´lescope a` Action Rapide pour les Objets Transitoires—Rapid Action Telescope for Transient Objects) represents a major step towards a relatively large observatory dedicated to the rapid observation of optical transients or variable sources. This completely autonomous observatory will feature a 1.5 meter telescope, with an imagery mode. A spectroscopic mode will be implemented, possibly on another telescope, linked to the imaging telescope as well as with TAROT-1. TAROT-2 will be fully autonomous, i.e., no human intervention will be required from the telescope schedule to the processing of the observations. The instrument will be networked with other instruments. New materials will be heavily used for all the optical and mechanical parts. The imaging telescope will have a 2° filed of view, and a maximum slew speed of 60 deg/s. A 8000×8000 pixel CCD camera will give a pixel size of 0.8—. If a new, interesting, source is detected by the imaging telescope, its position will be automatically sent to the spectroscopic telescope for immediate observation, i.e., for a GRB, while the source still has a large optical flux level. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1361634

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

Observation of prompt TeV &ggr;-rays from GRBs requires a new type of detector to overcome the low duty factor and small field of view of current TeV observatories. Milagro is such a new type of very high energy (> a few 100 GeV) gamma-ray observatory, which has a large field of view of >1 steradian and 24 hours/day operation. Milagrito, a prototype for Milagro, was operated from February 1997 to May 1998. During the summer of 1998, Milagrito was dismantled and Milagro was built. Both detectors use a80&hthinsp;m×60&hthinsp;m×8&hthinsp;mpond of water in which a3&hthinsp;m×3&hthinsp;mgrid of photomultiplier tubes detects the Cherenkov light produced in the water by the relativistic particles in extensive air showers. Milagrito was smaller and had only one layer of photomultipliers, but allowed the technique to be tested. Milagrito observations of the Moon’s shadow and Mrk 501 are consistent with the Monte Carlo prediction of the telescope’s parameters, such as effective area and angular resolution. Milagro will have improved flux sensitivity over Milagrito due to larger effective area, better angular resolution and cosmic-ray background rejection. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1361635

出版商:AIP    

年代:1900

数据来源: AIP