GCN Circular 34368
Subject
GRB 230805B : MITSuME Akeno optical upper limits
Date
2023-08-08T10:29:05Z (a year ago)
From
Narikazu Higuchi at Tokyo Tech <higuchi@hp.phys.titech.ac.jp>
Via
Web form
N. Higuchi, I. Takahashi, M. Sasada, M. Niwano, S. Sato, S. Hayatsu, R. Hosokawa, H. Seki, H. Takei, Y. Yatsu (Tokyo Tech) and N. Kawai (Riken) report on behalf of the MITSuME collaboration:
We observed the field of GRB 230805B (Cenko et al. GCN Circular #34339) with the optical three color (g', Rc, and Ic) CCD cameras attached to the MITSuME 50 cm telescope Akeno.
The observation started at 2023-8-05 11:25:51 UT (120 seconds after the Swift/BAT trigger). We stacked the images with good conditions. We did not detect any uncatalogued sources within the error region (Osborne et al. GCN Circular #34353). We obtained the 5-sigma limits of the stacked images as follows.
T0+[sec] | MID-UT | T-EXP[sec] | 5-sigma limits
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1117 | 2023-08-05 11:42:28 | 240.0 | g'>18.5, Rc>18.5, Ic>17.9
4357 | 2023-08-05 12:36:28 | 840.0 | g'>18.9, Rc>19.0, Ic>18.5
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T0+ : Elapsed time after the burst
T-EXP: Total Exposure time
We used the PS1 catalog for flux calibration. The catalog magnitudes in PS1 g, r and i bands were converted to our g', Rc and Ic band magnitudes following Tonry et al. (2012), Table 6. 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).