GCN Circular 5999

M. Stamatikos (NASA/ORAU), S.D. Barthelmy (GSFC), M. M. Chester (PSU),
G. Cusumano (INAF-IASFPA), W. B. Landsman (NASA/GSFC),
T. Mineo (INAF-IASFPA), D. M. Palmer (LANL) and
P. Romano (Univ. Bicocca & INAF-OAB) report on behalf of the Swift Team:

At 12:05:18 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 070107 (trigger=255029). Swift slewed immediately to the
burst. The BAT on-board calculated location is
RA, Dec 159.408, -53.208 which is
     RA(J2000)  = 10h 37m 38s
     Dec(J2000) = -53d 12'
27" with an uncertainty of 3 arcmin (radius, 90% containment,
including  systematic uncertainty). The BAT light curve showed a
broad peak lasting about 40 seconds with smaller structure. The peak
count rate was ~2500 counts/sec (15-350 keV), at ~6 sec after the
trigger.

The XRT began observing the field at 12:08:17.02 UT, 179 seconds after the
BAT trigger. XRT did not make an immediate localization. The lightcurve does not
show any time variability, however, the spectrum appears consistent
with that of a GRB. We are waiting for the full data set from the
next Malindi download data pass for futher analysis.

UVOT took a finding chart exposure of 100 seconds with the White
(160-650 nm) filter starting 181 seconds after the BAT trigger, and a
finding chart exposure of 400 seconds with the V filter starting 287
seconds after the BAT trigger. No afterglow candidate has been found
in the initial data products. The 2.7'x2.7' sub-image covers 25% of
the BAT error circle, and the 8'x8' region for the list of sources
generated on-board covers 100% of the BAT error circle. Because of
the density of catalogued stars, further analysis is required to
report an upper limit for any afterglow in the region. No correction
has been made for extinction.