GRB 091112

V. Mangano (INAF-IASFPA), W. H. Baumgartner (GSFC/UMBC),
S. Campana (INAF-OAB), P.A. Curran (MSSL-UCL),
C. Guidorzi (U Ferrara), S. T. Holland (CRESST/USRA/GSFC),
E. A. Hoversten (PSU), J. A. Kennea (PSU),
H. A. Krimm (CRESST/GSFC/USRA), J. Mao (INAF-OAB),
R. Margutti (Univ Bicocca&OAB), P. T. O'Brien (U Leicester),
K. L. Page (U Leicester), D. M. Palmer (LANL), M. H. Siegel (PSU),
M. Stamatikos (OSU/NASA/GSFC), M. A. Stark (PSU) and
T. N. Ukwatta (GSFC/GWU) report on behalf of the Swift Team:

At 17:41:21 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 091112 (trigger=375659).  Swift could not slew to the
burst due to the Sun constraint.  The BAT on-board calculated location is 
RA, Dec 257.728, -36.715 which is 
   RA(J2000) = 17h 10m 55s
   Dec(J2000) = -36d 42' 53"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a symmetrical peak
structure with a duration of about 20 sec.  The peak count rate
was ~2000 counts/sec (15-350 keV), at ~5 sec after the trigger. 

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

Because this location is about 10 degrees from the Galactic center,
we cannot rule out the possibility of this being a Galactic source. 
However, there are no known Galactic sources at this location. 

Burst Advocate for this burst is V. Mangano (vanessa AT ifc.inaf.it). 
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.)

M. S. Briggs (UAH) reports on behalf of the Fermi GBM Team:

"At 17:41:15.82 UT on 12 Nov 2009, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 091112 (trigger 279740477 / 091112.737),
which was also detected by the SWIFT-BAT (V. Mangano et al., GCN 10162
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The GBM on-ground location is consistent with the Swift position.
The angle from the Fermi LAT boresight is 82 degrees.

The GBM light curve consists primarily of a broad peak, and
has a duration of about 40 seconds.  
 
The time-averaged spectrum from T0-0.512 s to T0+24.064 s is
best fit by a power law function with an exponential
high energy cutoff.  The power law index is -1.13 +/- 0.04 and
the cutoff energy, parameterized as Epeak, is 750 +/- 120 keV.
C-Stat = 717 for 483 degrees of freedom.

The event fluence (10-1000 keV) in this time interval is
(9.7 +/- 0.3)E-6 erg/cm^2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."

D. M. Palmer (LANL), 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), V. Mangano (INAF-IASFPA), C. B. Markwardt (GSFC/UMD),
A. M. Parsons (GSFC), T. Sakamoto (GSFC/UMBC), G. Sato (ISAS),
M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC), T. N. Ukwatta (GWU)
(i.e. the Swift-BAT team):
 
Using the data set from T-60 to T+483 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 091112 (trigger #375659)
(Mangano, et al., GCN Circ. 10162
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 ).  The BAT ground-calculated position is
RA, Dec = 257.751, -36.729 deg, which is 
   RA(J2000)  =  17h 11m 00.2s 
   Dec(J2000) = -36d 43' 43.4" 
with an uncertainty of 1.5 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 40%.
 
The mask-weighted light curve shows a roughly symmetric peak starting
at ~T-15 sec, peaking at ~T+2 sec, and ending at ~T+40 sec.
T90 (15-350 keV) is 17 +- 4 sec (estimated error including systematics).
 
The time-averaged spectrum from T-10.0 to T+14.7 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.03 +- 0.14.  The fluence in the 15-150 keV band is 2.1 +- 0.4 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+0.56 sec in the 15-150 keV band
is 1.9 +- 0.5 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/375659/BA/

T. Sugasahara, M. Tashiro, Y. Terada, A. Endo, K. Onda,
W. Iwakiri (Saitama U.), S. Sugita(Nagoya U.), K. Yamaoka (Aoyama  
Gakuin U.),
M. Ohno, M. Suzuki, M. Kokubun, T. Takahashi (ISAS/JAXA),
Y. E. Nakagawa, T. Tamagawa (RIKEN), N. Ohmori, A. Daikyuji,
E. Sonoda, K. Kono, H. Hayashi, K. Noda, Y. Nishioka, M. Yamauchi
(Univ. of Miyazaki), N. Vasquez (Tokyo Tech.), Y. Urata, H.M  Lin (NCU),
Y. Hanabata, T. Uehara, T. Takahashi, Y. Fukazawa (Hiroshima U.),
T. Enoto, K. Nakazawa, K. Makishima (Univ. of Tokyo), S. Hong
(Nihon U.), on behalf of the Suzaku WAM team, report

The long GRB 091112 (Swift/BAT trigger #375659 ; Palmer et al., GCN  
10165
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 ;
Fermi/GBM trigger #279740477 ; Briggs et al., GCN 10164
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 )
triggered the Suzaku Wide-band All-sky Monitor (WAM) which covers an
energy range of 50 keV - 5 MeV at 2009-11-12 17:41:16.31 UT (=T0).

The observed light curve shows a multi-peaked structure starting at
T0-4s, ending at T0+16s with a duration (T90) of about 15 seconds.
The fluence in 100-1000 keV was 7.85(-2.91,+0.37)x10^-6  erg/cm2.
The 1-s peak flux measured from T0+7s was 1.25(-0.89,+0.09) photons/ 
cm2/s
in the same energy range.

Preliminary result shows that the time-averaged spectrum from
T0-4s to T0+16s is well fitted by a power-law with exponential cutoff  
model:
dN/dE ~ E^{-alpha} * exp(-(2-alpha)*E/Epeak) with
alpha 1.19(-0.76,+0.45), and
Epeak 628(-192,+607)keV (chi2/d.o.f. = 23.9/24).

All the quoted errors are at statistical 90% confidence level,
in which the systematic uncertainties are not included.

The light curves for this burst are available at:

http://www.astro.isas.jaxa.jp/suzaku/HXD-WAM/WAM-GRB/grb/trig/grb_table.html