GRB 090107

T. N. Ukwatta (GSFC/GWU), J. R. Cummings (NASA/UMBC),
N. Gehrels (NASA/GSFC), C. Guidorzi (U Ferrara),
S. T. Holland (CRESST/USRA/GSFC), J. A. Kennea (PSU),
W.B Landsman (GSFC), D. M. Palmer (LANL), M. Perri (ASDC) and
G. Stratta (ASDC) report on behalf of the Swift Team:

At 04:48:04 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 090107 (trigger=339295).  Swift could not slew
to this burst due to its proximity to the Sun. 
The BAT on-board calculated location is 
RA, Dec 302.426, +4.727 which is 
   RA(J2000) = 20h 09m 42s
   Dec(J2000) = +04d 43' 39"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a double-peaked
structure with a duration of about 25 sec, with a possible additional
peak at T+75 sec.  The peak count rate was ~2000 counts/sec (15-350 keV),
at ~0 sec after the trigger. 

Due to the Sun observing constraint, Swift cannot slew to the 
BAT position.  There will thus be no XRT or UVOT data for this trigger. 

Burst Advocate for this burst is T. N. Ukwatta (tilan.ukwatta AT gmail.com). 
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/too.html.)

G. Sato (ISAS), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC),
J. R. Cummings (GSFC/UMBC), E. E. Fenimore (LANL), N. Gehrels (GSFC),
H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC/UMD), D. M. Palmer (LANL),
T. Sakamoto (GSFC/UMBC), M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC),
T. N. Ukwatta (GWU)
(i.e. the Swift-BAT team):
 
Using the data set from T-240 to T+962 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 090107 (trigger #339295)
(Ukwatta, et al., GCN Circ. 8782
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 ).  The BAT ground-calculated position is
RA, Dec = 302.409, 4.744 deg, which is 
   RA(J2000)  =  20h 09m 38.2s 
   Dec(J2000) = +04d 44' 37.9" 
with an uncertainty of 2.4 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 74%.
 
The mask-weighted light curve shows two peaks.  The first is about 1.2 sec wide
and peaks at ~T+0.9 sec.  The second is about 6 sec wide and peaks at ~T+11 sec.
Because of the Sun observing constraint and because of a regular pre-planned 
target slew, the BAT has no data on this event past T+260 sec, until the next orbit.
T90 (15-350 keV) is 12.2 +- 0.7 sec (estimated error including systematics).
 
The time-averaged spectrum from T+0.2 to T+12.9 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.69 +- 0.27.  The fluence in the 15-150 keV band is 2.3 +- 0.5 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T+0.30 sec in the 15-150 keV band
is 1.1 +- 0.2 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level. 
 
The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/339295/BA/