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GCN Circular 32101

Subject
GRB 220521A: MITSuME Akeno optical upper limits
Date
2022-05-24T09:32:51Z (2 years ago)
From
Naohiro Ito at Tokyo Tech <n.ito@hp.phys.titech.ac.jp>
S. Sato, M. Sasada, K. L. Murata, R. Hosokawa, Y. Imai, N. Ito, M. Niwano,
Y. Takamatsu, M. Tateda, T. Hattori, Y. Yatsu, and N. Kawai (Tokyo Tech)
report on behalf of the MITSuME collaboration:

We observed the field of GRB 220521A (The Fermi GBM team GCN Circular
#32075, Dichiara et al. GCN Circular #32076, Evans et al. GCN Circular
#32077, Malesani and Pursimo et al. GCN Circular #32078, Fynboet al. GCN
Circular #32079, Evans et al. GCN Circular #32081, Goranskij et al. GCN
Circular #32082, Kuin and Dichiara GCN Circular #32085, Tohuvavohu et al.
GCN Circular #32086, Watson et al. GCN Circular #32087, Nazarov et al. GCN
Circular #32088, Poolakkil and Meegan GCN Circular #32089, Lien et al. GCN
Circular #32090, Strausbaugh et al. GCN Circular #32091) 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 2022-05-22
11:56:05 UT (12.6 hours after the Fermi/GBM trigger). We stacked the images
with good conditions. We did not detect the optical afterglow (Malesani et
al. GCN Circular #32078, Goranskij et al. GCN Circular #32082, Strausbaugh
et al. GCN Circular #32091, Rastinejad et al. GCN Circular #32097,
Cucchiara et al. GCN Circular #32099). We obtained the 5-sigma limits of
the stacked images as follows.

T0+[hour] | MID-UT | T-EXP[sec] | 5-sigma limits
------------------------------------------------------------------------------------------------
16.6 | 2022-05-22 15:56:34 | 6780 | g' > 19.3, Rc > 19.1, Ic > 18.6
------------------------------------------------------------------------------------------------
T0+ : Elapsed time after the burst
T-EXP: Total Exposure time

We 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).
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