[vsnet-grb-info 24026] GRB 191031D: MITSuME Akeno optical upper limits

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  26125
SUBJECT: GRB 191031D: MITSuME Akeno optical upper limits
DATE:    19/11/01 10:51:07 GMT
FROM:    Ogawa Futa at Tokyo Institute of Technology  <ogawa at hp.phys.titech.ac.jp>

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

We searched for the optical counterpart of GRB 191031D (The Fermi GBM 
team, GCN Circular #26111, V. D'Elia et al., GCN Circular #26112, Bagrat 
Mailyan, #26114) 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 19/11/01 08:18:36 UT. We did not find any new 
point
sources within the XRT circle (J.P. Osborne et al., GCN Circular #26117)
in all three bands.
We obtained the following 5-sigma limits for the magnitudes.

T0+[hour]   MID-UT    T-EXP[sec]    5-sigma limits
------------------------------------------------------------------------------------------------ 

  ~11.5         09:12:34    1680              g'>18.3, Rc>18.2, Ic>17.3
------------------------------------------------------------------------------------------------ 

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.