NASA SWIFT: GRB050721A: Swift-BAT detection of a weak burst

TITLE: GCN GRB OBSERVATION REPORT
NUMBER: 3654
SUBJECT: GRB050721A: Swift-BAT detection of a weak burst
DATE: 05/07/21 06:04:14 GMT
FROM: Angelo Antonelli at Obs. Astro. di Roma a.antonelli@mporzio.astro.it

GRB050721A: Swift-BAT detection of a weak burst

L.A. Antonelli (INAF/OAR), K. Page (U. Leicester), D. Morris (PSU), P. Romano (INAF/OAB), N. Gehrels (GSFC), P. Roming (PSU), P. Schady (MSSL), G. Tagliaferri (INAF/OAB) S. Barthelmy (GSFC), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), D. Palmer (LANL), on behalf of the Swift team:

At 04:29:14.28 UT, Swift-BAT triggered and located GRB050721 (trigger=146970). The spacecraft slewed immediately. The BAT on-board calculated location is RA, Dec 253.445d,-28.390d {+16h 53m 47s,-28d 23′ 22″} (J2000), with an uncertainty of 3 arcmin (radius, 90% containment, stat+sys). The BAT light curve shows a peak with a total duration of ~10 sec. The peak count rate was ~1000 counts/sec (15-350 keV), at ~5 seconds after the trigger.

The XRT started the observation at 04:32:20 UT with XRT in automatic state, 186 sec after the BAT Trigger. An uncatalogued X-ray source was detected at the following position RA, Dec 16h 53m 44.7s, -28d 22′ 53”.3 with an uncertainty of about 6 arcsec (90% containment). This is 42 arcsec from the BAT position reported above.

Based on the UVOT finding chart there is no new source at the XRT position.