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  • 1
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    Gamma Ray Burst Optical Counterpart Search Experiment (GROCSE) (1995)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: GROCSE (Gamma-Ray Optical Counterpart Search Experiments) is a system of automated telescopes that search for simultaneous optical activity associated with gamma ray bursts in response to real-time burst notifications provided by the BATSE/BACODINE network. The first generation system, GROCSE 1, is sensitive down to Mv (approximately) 8.5 and requires an average of 12 seconds to obtain the first images of the gamma ray burst error box defined by the BACODINE trigger. The collaboration is now constructing a second generation system which has a 4 second slewing time and can reach Mv (approximately) 14 with a 5 second exposure. GROCSE 2 consists of 4 cameras on a single mount. Each camera views the night sky through a commercial Canon lens (f/1.8, focal length 200 mm) and utilizes a 2K x 2K Loral CCD. Light weight and low noise custom readout electronics were designed and fabricated for these CCDs. The total field of view of the 4 cameras is 17.6 x 17.6 (degree). GROCSE 2 will be operated by the end of 1995. In this paper, the authors present an overview of the GROCSE system and the results of measurements with a GROCSE 2 prototype unit.
    Keywords: Space Radiation
    Type: UCRL-JC-123539 , CONF-9510332-6 , DE96-009810 , Huntsville Symposium on Gamma Ray Bursts; Oct 25, 1995 - Oct 27, 1995; Huntsville, AL; United States
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  • 2
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    Results from GROCSE I: A real-time search for gamma ray burst optical counterparts (1995)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The GROCSE I experiment (Gamma-Ray Optical Counterpart Search Experiment) is a rapid slewing wide field of view optical telescope at Lawrence Livermore National Laboratory which responds to triggers from the BATSE GRB data telemetry stream that have been processed and distributed by the BACODINE network. GROCSE 1 has been in continuous automated operation since January 1994. As of October 1995, sky images for 22 GRB triggers have been recorded, in some cases while the burst was still emitting gamma rays. The preliminary analysis of eight of these events are presented here. No optical counterparts have yet been detected. Limits for optical emission are given.
    Keywords: Space Radiation
    Type: UCRL-JC-123538 , CONF-9510332-5 , DE96-009809 , Huntsville Symposium on Gamma Ray Bursts; Oct 25, 1995 - Oct 27, 1995; Huntsville, AL; United States
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  • 3
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    A Search for Simultaneous Optical Counterparts of Gamma-Ray Bursts (LOTIS: Livermore Optical Transient Imaging System) (1999)
    In:  CASI
    Details
    Publication Date: 2019-07-10
    Description: Under this grant the UC Berkeley PI, K. Hurley, joined the LOTIS collaboration. His task was to provide precise localization data on cosmic gamma-ray bursts, so that the LOTIS automated camera data could be searched more efficiently for evidence of optical emission from gamma-ray burst sources. This was accomplished. A program is now in place which automatically sends Interplanetary Network data on bursts via e-mail to H.S. Park, for every burst detected by the GRB experiment aboard the Ulysses spacecraft (for which K. Hurley is the P.I.). The data consist either of triangulation annuli (obtained when just two spacecraft observe the burst) or error boxes (when three widely separated spacecraft observe it). These define a locus of possible burst positions. The annuli intersect the large error circles of the CGRO-BATSE experiment, and reduce their areas by a factor of approximately 25 or more. The error boxes reduce the areas by factors of several hundred. This in turn reduces the area which must be searched for an optical counterpart. No such counterparts have been observed to date by the LOTIS experiment, but several interesting upper limits have been obtained.
    Keywords: Space Radiation
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  • 4
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    New Constraints on Simultaneous Optical Emission from Gamma-Ray Bursts Measured by the Livermore Optical Transient Imaging System Experiment (1997)
    In:  Other Sources
    Details
    Publication Date: 2019-07-17
    Description: LOTIS is a gamma-ray burst optical counterpart search experiment located near Lawrence Livermore National Laboratory in California. Since operations began in 1996 October, LOTIS has responded to five triggers as of 1997 July 30, which occurred during good weather conditions. GR-B 970223 (BATSE trigger 6100) was an exceptionally strong burst, lasting approx. 30 s with a peak at approx. 8 s. LOTIS began imaging the error box approx. 11 s after the burst began and achieved simultaneous optical coverage of 100% of the region enclosed by the BATSE 3 sigma error circle and the interplanetary network annulus. No optical transients were observed brighter than the m{}_{V} approx.11 completeness limit of the resulting images, providing a new upper limit on the ratio of simultaneous optical to gamma-ray fluence of R-{L) less than 1.1 x 10 logical and {-4} and on the ratio of simultaneous optical (at 700 mn) to gamma-ray (at 100 keV) flux density of R-{F} less than 305 for a B-type spectrum and R-{F} less than 475 for an M-type spectrum.
    Keywords: Space Radiation
    Type: Astrophysical Journal Letters; 490; L21
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  • 5
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    Real-Time Optical Flux Limits from Gamma-Ray Bursts Measured by the Gamma-Ray Optical Counterpart Search Experiment (1997)
    In:  Other Sources
    Details
    Publication Date: 2019-07-17
    Description: The Gamma-Ray Optical Counterpart Search Experiment presents new experimental upper limits on the optical flux from gamma-ray bursts (GRBs). Our experiment consisted of a fully automated very wide-field opto-electronic detection system that imaged locations of GRBs within a few seconds of receiving trigger signals provided by BATSE's real-time burst coordinate distribution network. The experiment acquired 3800 observing hours, recording 22 gamma-ray burst triggers within approx. 30 s of the start of the burst event. Some of these bursts were imaged while gamma-ray radiation was being detected by BATSE. We identified no optical counterparts associated with gamma-ray bursts among these events at the mV approx. 7.0-8.3 sensitivity level. We find the ratio of the upper limit to the V-band optical flux, F nu, to the gamma-ray fluence, Phi gamma, from these data to be 1 x 10(exp-18) less than F nu Phi gamma less than 2 x 10(exp -16).
    Keywords: Space Radiation
    Type: Astrophysical Journal; 490; 99
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