GRB 090305B
GCN Circular 8972
Subject
GRB090305B: Fermi GBM detection
Date
2009-03-10T17:50:24Z (16 years ago)
From
Colleen A. Wilson at NASA/MSFC/NSSTC <colleen.wilson@nasa.gov>
Colleen A. Wilson-Hodge (NASA/MSFC)
reports on behalf of the Fermi GBM Team:
"At 01:14:35.72 UT on 05 March 2009, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 090305B (trigger 257908477 / 090305052).
The on-ground calculated location, using the GBM trigger data, is
RA = 155.1, DEC = 68.1 (J2000 degrees, equivalent to 10 h 20 m, 68 d 06'),
with an uncertainty of 5.4 degrees (radius, 1-sigma containment,
statistical only; there is additionally a systematic error which is
currently estimated to be 2 to 3 degrees).
The angle from the Fermi LAT boresight is 40 degrees.
The GBM light curve shows/consists of a single peak with a duration (T90)
of about 2 s (8-1000 keV). The time-averaged spectrum from T0-0.5 s to
T0+2.5 s is best fit by a Band function with Epeak = 770+/- 230 keV,
alpha = -0.50 +/- 0.17, and beta = -1.9 +/- 0.2.
The event fluence (8-1000 keV) in this time interval is
(2.7 +/- 0.2)E-06 erg/cm^2. The 64-msec peak photon flux measured
starting from T0+0.288 s in the 8-1000 keV band is 11 +/- 2 ph/s/cm^2.
The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."
GCN Circular 9004
Subject
GRB090305B: MASTER-net prompt optical short burst observations
Date
2009-03-16T10:21:16Z (16 years ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <gcncirc@observ.inetcomm.ru>
E. Gorbovskoy, V. Lipunov, V.Kornilov, A.Belinski, N.Shatskiy, N.Tyurina,
D.Kuvshinov, P.Balanutsa, V.V.Chazov, P.V.Kortunov
Sternberg Astronomical Institute, Moscow State University
A. Tlatov, A.V. Parhomenko,
Kislovodsk Solar Station of the Pulkovo Observatory
V.Krushinski, I.Zalognikh, T.Kopytova
Ural State University, Kourovka
S.Yazev, K.Ivanov
Irkutsk State University
There are 6 MASTER Very Wide Field cameras located at Kislovodsk and Irkutsk
with common FOW = 6000 square degrees (http://observ.pereplet.ru/).
One of the four MASTER Very Wide Field Cameras located at Kislovodsk
(D=50 mm, 4x1000 square degrees, 11 Mpx) has observed ~80% 1-sigma Fermi
error box (Colleen A. Wilson-Hodge, GCN 8972) with 1s exposure
during all night: 7 hours befoure, during and 1 hours after GRB Time
without time gap between images.
Our unfiltered images are calibrated relative to Tycho stars (V).
The magnitude limit of the each emage is ~9.5 m at the edge of FOW.
We do not detect OT inside part of the error box (Colleen A. Wilson-Hodge, GCN
8972) brighter than 9.2 mag before and after trigger time.
We conclude in case that GRB inside our FOW that:
1). the optical fluence during the short 2 s GRBurst is limited by
~<= 1 x 10E-8 erg/cm_2
excluding possible host galaxy absorbtion.
The event fluence (8-1000 keV) in this time interval is
(2.7 +/- 0.2)E-06 erg/cm^2 (Colleen A. Wilson-Hodge, GCN
8972).
So:
2). Optical-Fluence/Gamma-Fluence(8-1000 keV) ~ < 1/100
The same ratio for long GRB080319B is
Optical-Fluence/Gamma-Fluence(8 - 1000 keV) ~ 1/140
(Naked Eye GRB, Racusin, Karpov et al., Nature, vol.455, 183, 2008).
The film of our observations (from 10 s before and 15 s after GRB time) is
available at
http://observ.pereplet.ru/images/GRB090305B/GRB090305B_full2.gif
White & black circles are the 1-sigma & 3-sigma+systematic (2 degrees)
error boxes correspondingly. Black rectangle is the IPN error box (Palshin et al., private
communication).
The FOWs of the 2 cameras are available at
http://observ.pereplet.ru/images/GRB090305B/FOW090305.png
The reduction is continued.
The message may be cited.
mailto: lipunov@sai.msu.ru