[vsnet-grb-info 24677] GRB 200115A: MITSuME Okayama optical upper limits

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  26776
SUBJECT: GRB 200115A: MITSuME Okayama optical upper limits
DATE:    20/01/15 15:01:10 GMT
FROM:    Masafumi Niwano at Tokyo Institute of Tech  <niwano at hp.phys.titech.ac.jp>

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

We searched for the optical counterpart of GRB 200115A (S. B. Cenko et 
al.,GCN Circular #26771) with the optical three color (g', Rc, and Ic) 
CCD cameras attached to the MITSuME 50 cm telescope of Okayama 
Astrophysical Observatory, Okayama, Japan.
The observation started on 11:52:38.68 UT. We did not find any new point 
sources within the Swift/BAT circle (S. B. Cenko et al., GCN Circular 
#26771) in all three bands.
We obtained the 5-sigma limits as follows.

T0+[sec]   MID-UT    T-EXP[sec]    5-sigma limits
------------------------------------------------------------------------------------------------
135   12:23:04.98   3060   g'>18.3, Rc>17.6, Ic>17.2
------------------------------------------------------------------------------------------------
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.
The images were processed in real-time through the MITSuME GPU reduction 
pipeline (Niwano et al. ,in prep; https://github.com/MNiwano/Eclair)