GCN Circular 32625

M. Tateda, I.Takahashi, K. L. Murata, Y. Imai, N. Ito, M. Niwano, S.
Sato, N. Higuchi, Y. Takamatsu, R. Hosokawa, M. Sasada, Y. Yatsu, and
N. Kawai (Tokyo Tech) report on behalf of the MITSuME collaboration:We
observed the field of GRB 220930A (S. B. Cenko et al. GCN Circular
#32603, Alan M. Watson et al. GCN Circular #32604, The Swift-XRT team
GCN Circular #32605,, Y.-D. Hu et al. GCN Circular #32606, V. Lipunov
et al. GCN Circular #32607, P.A. Evans et al. GCN Circular #32608, A.
Belles et al. GCN Circular #32609, R. Strausbaugh et al. GCN Circular
#32610, V. D'Elia et al. GCN Circular #32611, S. D. Barthelmy et al.
GCN Circular #32612, R. Gopalakrishnan et al. GCN Circular #32613,
A.Ridnaia et al. GCN Circular #32614, N. Pankov et al. GCN Circular
#32617) with the optical three color (g', Rc, and Ic) CCD cameras
attached to the MITSuME 50 cm telescope Akeno.The observation with a
series of 60 sec exposures started at 2022-09-30 13:10:00 UT (118.1
minutes after the Swift/BAT trigger). We stacked the images with good
conditions. We did not detect any uncatalogued sources within the
enhanced Swift/XRT error region (Evans et al. GCN Circular #32608). We
obtained the 5-sigma limits of the stacked images as follows.T0+[days]
| MID-UT | T-EXP[sec] | 5-sigma limits
------------------------------------------------------------------------------------------------
0.23 | 2022-09-30 16:39:02.52 | 14460 | g'>21.0, Rc>20.9, Ic>20.4
------------------------------------------------------------------------------------------------
T0+ : Elapsed time after the burst
T-EXP: Total Exposure timeWe used PS1 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. 2021, PASJ, Vol.73, Issue 1, Pages 4-24;
https://github.com/MNiwano/Eclaire)..