NASA SWIFT: GRB 050713B

TITLE: GCN GRB OBSERVATION REPORT
NUMBER: 3590
SUBJECT: GRB 050713B
DATE: 05/07/13 13:09:51 GMT
FROM: Simon Vaughan at Leicester U/BA sav2@star.le.ac.uk

S. Vaughan (Leicester), A. Falcone (PSU), D. Palmer (LANL), A. Blustin (MSSL), S. Barthelmy (GSFC), J. Cummings (GSFC/NRC), H. Krimm (GSFC/USRA), D. Burrows, D. Morris, C. Gronwall (PSU), C. Markwardt (GSFC/UMD), K. Page, M. Goad (Leicester), S Rosen (MSSL), N. Gehrels (GSFC)

At 12:07:17.62 UT, the Swift Burst Alert Telescope (BAT) triggered and located on-board GRB050713B (trigger=145754). The spacecraft slewed immediately. The flight-determined location is RA,Dec 307.843,+60.920 {20h 31m 22s,+60d 55′ 12″} (J2000) with an uncertainty of 3 arcmin (radius, 90% c.l. stat+sys). The burst lightcurve has 1 (maybe 2) peaks within ~30 sec duration. It is riding on top of two long bumps which are believed to be background, but without the full Malindi data, we can not determine if the bumps are background or burst-related. The peak rate (without bumps) is ~1000 cnts/sec in the 15-350 keV band.

The spacecraft slewed immediately and the XRT began observing the burst at 12:09:33 UT (136 s after the BAT trigger). XRT found a bright, uncataloged, fading X-ray source at:

RA: +20h 31m 15.5s (J2000),
DEC: +60d 56′ 38.4″ (J2000).

This position is 100 arcseconds from the BAT position. The estimated uncertainty is 6 arcseconds radius (90% containment).

The Swift Ultra Violet/Optical Telescope (UVOT) observations began at 12:09:33 UT, 136 seconds after the BAT trigger. The first data taken after the spacecraft settled was a 100 sec exposure using the V filter with the midpoint of the observation at 186 sec after the BAT trigger. Based on comparisons to the DSS, we detect no new source at the XRT position.