[vsnet-grb-info 22189] GRB 190427A: MITSuME Akeno optical upper limits

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  24288
SUBJECT: GRB 190427A: MITSuME Akeno optical upper limits
DATE:    19/04/27 15:58:22 GMT
FROM:    Katsuhiro L. Murata at Nagoya U  <murata at u.phys.nagoya-u.ac.jp>

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

We searched for the optical counterpart of GRB 190427A (Tohuvavohu et al.,
GCN Circular #24261) 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 13:16:48 UT. We did not find any new point
sources within the BAT circle (Tohuvavohu et al., GCN Circular #24261) in
all three bands.
We obtained the following 5-sigma limits for the magnitudes.

T0+[hour]   MID-UT    T-EXP[sec]                           5-sigma limits
------------------------------------------------------------------------------------------------
 ~8.7         13:35:08   1620(g'),1560(Rc),1980(Ic)   g'>17.8,Rc>18.2,Ic
>18.6
------------------------------------------------------------------------------------------------
T0+ : Elapsed time after the burst
T-EXP: Total Exposure time
We used GSC2.3 catalog for flux calibration.
The magnitudes are expressed in the AB system.