{
  "bibcode": "1999GCN...306....1K",
  "body": "R. M. Kippen (University of Alabama in Huntsville) reports on behalf\nof the BATSE GRB team:\n\nGRB 990506 was detected by BATSE on 1999 May 6.474664 as trigger\nnumber 7549.  The event was strong and consisted of a multi-peaked\ntemporal structure lasting >150 s, with significant spectral\nevolution.  The T50 and T90 durations are 112.06 (-/+ 0.09) s and\n131.33 (-/+ 0.20) s, respectively.  The burst's peak flux (50-300 keV;\nintegrated over 1.024 s) and fluence (>20 keV) are 18.58 (-/+ 0.13)\nphotons cmE-2 sE-1 and 2.23 (-/+ 0.02) x 10E-4 erg cmE-2,\nrespectively---ranking it in the top 2% (1%) of the BATSE burst flux\n(fluence) distribution.  The average spectral hardness of the burst,\nas estimated by the ratio of 100-300 keV counts to those in the 50-100\nkeV range, is H32 = 0.909 (-/+ 0.003), which is average among BATSE\nbursts of this duration.  The BATSE burst location is consistent with\nthat measured by the IPN (BATSE/Ulysses/NEAR; GCN 298) and was used to\ninitiate an RXTE-PCA scan observation that resulted in the detection\nof a fading x-ray source; probably the GRB afterglow (see GCN alert\nnotices).  A location sky-map and lightcurve for this event (and other\nnotable bursts) are available at the BATSE Rapid Burst Response\nworld-wide-web site:\n\n          http://www.batse.msfc.nasa.gov/~kippen/batserbr/\n\n-eof-\n\n[GCN OP NOTE (10May99):  Due to a programming problem in processing this\nCircular so close in time to the previous Circular, the NUMBER was erroneously\nassigned to be 305, when in fact it should have been 306.  The archive copies\nhave been fixed.]",
  "circularId": 306,
  "createdOn": 926359270000,
  "email": "marc.kippen@msfc.nasa.gov",
  "subject": "GRB 990506: BATSE Observations",
  "submitter": "R. Marc Kippen at BATSE/UAH/MSFC  <marc.kippen@msfc.nasa.gov>",
  "eventId": "GRB 990506"
}