[vsnet-grb-info 12848] GRB 130131A: MITSuME Akeno Optical upper limits

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  14194
SUBJECT: GRB 130131A: MITSuME Akeno Optical upper limits
DATE:    13/02/10 14:00:06 GMT
FROM:    Yoichi Yatsu at Tokyo Tech.  <yatsu at hp.phys.titech.ac.jp>

M. Hayashi, T. Yoshii, R. Usui, Y.Aoki, S. Kurita,
Y. Saito, Y. Yatsu, and N. Kawai (Tokyo Tech)
report on behalf of the MITSuME collaboration:

We observed GRB 130131A (Grupe et al., GCNC 14156) 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 2013-01-31 13:57:11 UT ( ~49 sec after
the burst). And we could not find any new point source within the XRT
error circle in all the three bands.
The results of photometry (3 sigma upper limits) are listed below.

The photon flux were calibrated against GSC2.3 catalog.

T0+[sec]   MID-UT   T-EXP[sec]    g'           Rc          Ic
-------------------------------------------------------------------------------------------
     33       13:57:44      60        >17.6   >17.8   >17.1
    159      13:59:51      270      >18.5   >18.6   >18.0
   1105     14:15:46      1440     >19.0   >19.4   >18.9
   7119     15:56:00      9540     >19.9   >20.6   >19.8
-------------------------------------------------------------------------------------------
T0+ : Elapsed time after the burst [sec]
T-EXP: Total Exposure time [sec]