[vsnet-grb-info 6151] Swift analysis of BAT Slew Survey event (Trigger=009)

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  7780
SUBJECT: Swift analysis of BAT Slew Survey event (Trigger=009)
DATE:    08/06/01 22:47:46 GMT
FROM:    Eleonora Troja at INAF-IASFPA  <nora at ifc.inaf.it>

E. Troja (U.  Leicester/INAF-IASFPA), S. Barthelmy (GSFC),
J. Cummings (GSFC/UMBC), A. Copete (Harvard),
J. Grindlay (Harvard), P. Evans (U. Leicester)
report:

At 01:17:20 UT on 2008-05-31, BAT detected a source during a spacecraft
slewing interval (when normal BAT triggering is disabled). This event
(ID_Num=009) was detected using the BAT Slew Survey (BATSS) method and
classified it as 'Silver plated' -- highly likely to be a GRB. The
location is
   RA(J2000) = 22h 53m 24s
  Dec(J2000) = +54d 57' 00"
with an uncertainty of 7.7 arcmin.
This was initially distributed as a GCN/BAT_SLEW_POS Notice at 13:53 UT,
12.6 hrs after the slew.
The Swift BAT team performed a further analysis of the event data during
this slew. No sign of a source was found at the BATSS position with a
3 sigma upper limit of 0.10 cts/s.

A  2 ks ToO observation of the location started at 15:42 UT, 14.4 hrs
after the slew. The XRT observation (Photon Counting mode) detected
an X-ray source with a count rate of 0.04 cts/s. Its position is

   RA(J2000) = 22h 53m 08.54s
  Dec(J2000) = +55d 04m 34.0s

with an uncertainty of 4.6 arcsec (90% confidence). This is at the edge
of the BATSS error circle. This source shows no indication of fading over
the 2 ks interval.

We therefore conclude that this event is not a GRB and that the source
found by XRT is an unassociated field object.