GCN Circular 12893
Subject
GRB 111225A: optical observations
Event
Date
2012-01-21T22:04:47Z (15 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
A.Volnova (SAI MSU), E. Klunko (ISTP), M. Andreev, A. Sergeev (Terskol
Branch of INASAN), A. Pozanenko (IKI) on behalf of larger GRB follow up
collaboration report:
We observed the field of GRB 111225A (Siegel et al., GCN 12720) with
AZT-33IK telescope of Sayan observatory (Mondy) on Dec. 25 between (UT)
17:37:41 - 18:25:58 in R filter under mean seeing (FWHM) of about 2.0".
We also observed the field with Zeiss-2000 telescope of Mt. Terskol
observatory on Dec. 26 between (UT) 17:37:23-18:46:37 in BRI filters under
poor seeing (FWHM) of about 4.4". On stacked images of both epochs we did
not find an optical counterpart (Siegel et al., GCN 12720; Klotz et al.,
GCN 12722; Adria et al., GCN 12723; Wren et al., GCN 12803).
The photometry is based on the USNO-B1.0 star 1415-0025726 (J2000)
00:52:35.11 +51:33:58.9, assuming B = 17.56, R =16.50, I = 16.20:
T0+, Filter, Exposure, OT, UL(3 sigma), Telescope
(mid, d) (s)
0.63278 R 24 x 120 n/d 22.5 AZT-33IK
1.58789 B 10 x 90 n/d 22.0 Zeiss-2000
1.60285 R 10 x 90 n/d 21.5 Zeiss-2000
1.61677 I 10 x 90 n/d 20.5 Zeiss-2000
Upper limits above are consistent with upper limits of R~22.5 reported by
Sonbas et al. (GCN 12740) and observations of the afterglow at R ~ 23.2 on ~
1day after burst trigger (Cenko et al., GCN 12733). Taking into account the
positive detection of the afterglow on 3.7590 days at R~22.5 (Rumyantsev et
al., GCN 12793) one can suggest a strong rebrightening of the afterglow
which is a rare case of late afterglow (3.7590 days) of an apparently
nearby burst (cf. UVOT optical detection in uvw2 filter (Siegel, GCN
12735).