GCN Circular 7764

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.