TITLE: GCN GRB OBSERVATION REPORT NUMBER: 400 SUBJECT: GRB990806: BATSE Observations DATE: 99/08/10 16:33:14 GMT FROM: Timothy Giblin at MSFC T. Giblin, G. Richardson, and R. M. Kippen (University of Alabama in Huntsville) report on behalf of the BATSE GRB Team: GRB990806 was detected by BATSE on 1999 August 6.60285 UT as trigger 7701. The time profile of the burst exhibits a FRED-like structure (fast rise and slower decay) with some variability on shorter time scales. The T50 and T90 durations are 4.93 (+/- 0.26) and 17.41 (+/- 3.84) seconds, respectively. The peak flux of the burst, integrated over 1.024 s in the 50-300 keV range, is 1.60 (+/- 0.05) photons cmE-2 sE-1, placing it in the top 28% of the BATSE peak flux distribution. The fluence (>20 keV) of the burst is 3.29 (+/- 0.53) x 10E-6 erg cmE-2, ranking it in the top 43% of the BATSE fluence distribution. The average spectral hardness of the burst (H32), as determined by the ratio of total counts in the 100-300 keV to the 50-100 keV range, is 0.811 (+/- 0.034), average for BATSE GRBs of this duration. The BATSE location error circle (90% conf.) is slightly offset (~2 degrees) from the BeppoSAX WFC location (GCN 393). The lightcurve and skymap location that includes the WFC and BATSE locations for this event (and other notable GRBs) are available at the BATSE Rapid Burst Response world-wide-web site: http://www.batse.msfc.nasa.gov/~kippen/batserbr/