[vsnet-grb-info 24498] GRB 191227A: MITSuME Akeno optical upper limits

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  26597
SUBJECT: GRB 191227A: MITSuME Akeno optical upper limits
DATE:    19/12/27 10:31:08 GMT
FROM:    Adachi Ryo at Tokyo Institute of Tech  <adachi at hp.phys.titech.ac.jp>

R. Adachi, K. L. Murata, M. Oeda, K.Shiraishi, K. Iida, M. Niwano, F.
Ogawa, R. Hosokawa, S. Toma, N. Nakamura, Y. Yatsu, and N. Kawai
(TokyoTech) report on behalf of the MITSuME collaboration:

We observed the field of the optical counterpart (V. Lipunov et al.
#26596) of GRB 191227A (The Fermi GBM team #26593, A. Melandri et al.
#26595) with the optical three color (g’, Rc, and Ic) CCD cameras
attached to the MITSuME 50 cm telescope of Akeno Observatory,
Yamanashi, Japan.

The observation started on 19/12/27 08:08:42.73 UT. We did not detect
the optical counterpart in all three bands. We obtained the following
5-sigma limits for the magnitudes.

T0+[hour]    MID-UT T-EXP[sec]   5-sigma limits
-----------------------------------------------------------------------------------------------------
~6.75        08:57:46.67 3360         g’>17.4, Rc>16.9, Ic>16.2
-----------------------------------------------------------------------------------------------------
T0+ : Elapsed time after the burst
T-EXP: Total Exposure time
We used UCAC4 catalog for flux calibration.
The magnitudes are expressed in the AB system.