//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7764 SUBJECT: GRB080521(?): detection of possible burst from BAT slew data and XRT ToO DATE: 08/05/22 23:51:40 GMT FROM: Antonio Copete at Harvard U A. Copete, J. Grindlay (Harvard), J. Racusin (PSU) S.Barthelmy, N. Gehrels (GSFC) We report on the detection by the BAT Slew Survey (BATSS) of a possible burst in the slew that began on 05/21/08 at 03:58:02 UT, at the position: RA (J2000): 12h 08m 44s Dec(J2000): +30d 34' 57" with an uncertainty of 6.4 arcmin (90% confidence). This detection is an image trigger from 6.4 sigma and 4.8 sigma detections in the 15-150keV and 50-150keV energy bands, respectively. The lightcurve features a downward sloping profile which suggest a main peak may have occurred before the slew. The detection was followed by an XRT ToO observation beginning on 05/22/08 at 15:30 UT. The 4ks observations yielded an uncatalogued X- ray source within the BATSS error circle at RA(J2000) = 12h 08m 49.54s Dec(J2000) = +30d 33' 32.68" with an uncertainty of 5.4 arcsec (90% confidence), and a count rate of 0.022+/-0.004 counts/s. No indication of fading was found, however, which could be due the relatively short exposure time compared to the delay of more than a day from the initial BAT observation. A follow-up XRT observation will be scheduled in order to determine fading.