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Record Details

Record 27 of 66
Observations of GRB 990123 by the Compton Gamma Ray Observatory
Author and Affiliation:
Briggs, M. S.(Alabama Univ., Huntsville, AL United States)
Band, D. L.(California Univ., San Diego, La Jolla, CA United States)
Kippen, R. M.(Alabama Univ., Huntsville, AL United States)
Preece, R. D.(Alabama Univ., Huntsville, AL United States)
Kouveliotou, C.(Universities Space Research Association, Huntsville, AL United States)
vanParadijs, J.(Alabama Univ., Huntsville, AL United States)
Share, G. H.(Naval Research Lab., Washington, DC United States)
Murphy, R. J.(Naval Research Lab., Washington, DC United States)
Matz, S. M.(Northwestern Univ., Evanston, IL United States)
Connors, A.(Wellesley Coll., MA United States) Show more authors
Abstract: GRB 990123 was the first burst from which simultaneous optical, X-ray, and gamma-ray emission was detected; its afterglow has been followed by an extensive set of radio, optical, and X-ray observations. We have studied the gamma-ray burst itself as observed by the Compton Gamma Ray Observatory detectors. We find that gamma-ray fluxes are not correlated with the simultaneous optical observations and that the gamma-ray spectra cannot be extrapolated simply to the optical fluxes. The burst is well fitted by the standard four-parameter GRB function, with the exception that excess emission compared with this function is observed below approx. 15 keV during some time intervals. The burst is characterized by the typical hard-to-soft and hardness-intensity correlation spectral evolution patterns. The energy of the peak of the vf (sub v), spectrum, E (sub p), reaches an unusually high value during the first intensity spike, 1470 plus or minus 110 keV, and then falls to approx. 300 keV during the tail of the burst. The high-energy spectrum above approx. 1 MeV is consistent with a power law with a photon index of about -3. By fluence, GRB 990123 is brighter than all but 0.4% of the GRBs observed with BATSE (Burst and Transient Source Experiment), clearly placing it on the -3/2 power-law portion of the intensity distribution. However, the redshift measured for the afterglow is inconsistent with the Euclidean interpretation of the -3/2 power law. Using the redshift value of greater than or equal to 1.61 and assuming isotropic emission, the gamma-ray energy exceeds 10 (exp 54) ergs.
Publication Date: Oct 10, 1999
Document ID:
20000012413
(Acquired Feb 06, 2000)
Subject Category: SPACE RADIATION
Document Type: Journal Article
Publication Information: Astrophysical Journal; Volume 524; 82-91
Publisher Information: American Astronomical Society, United States
Contract/Grant/Task Num: NAS5-26646; NAG5-7927; DARA-50QV-90968; NAG5-7984; NAG5-7829; NAG5-6747; NAG5-7894
Financial Sponsor: NASA Goddard Space Flight Center; Greenbelt, MD United States
Netherlands Organization for Applied Scientific Research TNO; Delft, Netherlands
Wellesley Coll.; MA United States
Defense Advanced Research Projects Agency; Arlington, VA United States
Organization Source: NASA Goddard Space Flight Center; Greenbelt, MD United States
Description: 12p; In English
Distribution Limits: Unclassified; Publicly available; Unlimited
Rights: Copyright
NASA Terms: GAMMA RAY BURSTS; AFTERGLOWS; LIGHT EMISSION; OPTICAL EMISSION SPECTROSCOPY; X RAYS; GAMMA RAY OBSERVATORY; DATA PROCESSING; SCINTILLATION COUNTERS; FLUX DENSITY; VISUAL OBSERVATION; EUCLIDEAN GEOMETRY; PHOTONS
Availability Source: Other Sources
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