GCN Circular 9038
Subject
GRB 090320B: MASTER-Net prompt optical observations
Date
2009-03-25T16:39:43Z (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 (P. N. Bhat, GCN 9020) with 1s exposure
during all night: befoure, during and 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 ~9.0 m at the edge of FOW (some
ising was attend at this night).
We do not detect OT inside 80% part of the error box.
T-T_trigger m_lim (S/N=3) Exposure Coadd
-10s... 0... 60 s 9.0 1 s no
-1min...0...+1 min 10.5 10 s 10
-1min...0...+1 min 11.0 60 s 60
We conclude (in the case that GRB inside our FOW ):
1). the optical fluence during the short 58 s GRBurst is limited by
~<= 1.5 x 10E-8 erg/cm_2
excluding possible host galaxy absorbtion.
The event fluence (8-1000 keV) in this time interval is
(1.1 +/- 0.3)E-06 erg/cm^2 (P. N. Bhat, GCN 9020).
So:
2). Optical-Fluence/Gamma-Fluence(8-1000 keV) ~ < 1/70
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 to 60 s after GRB time)
is available at
http://observ.pereplet.ru/images/GRB090320B/GRB090320b_10sec_bin.gif
Black circle is the 1-sigma (9.5 degrees, P. N. Bhat, GCN 9020)
error box.
The film of added images (60s effective exposition) our observations (from
-60s before to 60 s after GRB time)is available at
http://observ.pereplet.ru/images/GRB090320B/GRB090320B_60sec.gif
The reduction is continued.
The message may be cited.
mailto: lipunov@sai.msu.ru
T-T_trigger m_lim (S/N=3) Exposure Coadd
-255s... 0... 255 s 11.8 5s yes
-2min...0...+2 min 12.7 2x30s 12
-2min...0...+2 min 13.0 2x60s 24
The optical fluence during the 40s-GRBurst is limited by
<= 1.6x10_-8 erg/cm_2
including 2.8 magnitude absorbtion (Ukwatta et al., Circ 8462).
The BAT-fluence is aboute 2.3x10_-6 erg/cm_2 (15-150 keV) (Fenimore et al.,
GCN 8468).
So:
Optical Fluence/Gamma-Fluence(15-150keV) ~ < 1/140
Same ratio for GRB080319B is ~ 1/25 (Naked Eye GRB) in 15-150 keV (Racusin,
Karpov et al., Nature, vol.455, 183, 2008).
Scientific Master Team Report are available at
http://observ.pereplet.ru/images/GRB081102/grb_film.html
Note: the GRB was at the edge of the FOW in both cameras.
The message may be cited.
mailto: lipunov@sai.msu.ru