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GCN Circular 35133

GRB 231117A : MITSuME Akeno optical afterglow candidate detection
2023-11-20T12:14:35Z (6 months ago)
Ichiro Takahashi at Tokyo Tech <>
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I. Takahashi, H. Takei, N. Higuchi, M. Sasada, M. Niwano, S. Sato, S. Hayatsu, H. Seki, Y. Yatsu and N. Kawai (Tokyo Tech) report on behalf of the MITSuME collaboration:

After our previous report (Takei et al., GCN 35076), we reanalyzed all of the GRB 231117A field data observed by the MITSuME 50 cm telescope Akeno on Nov. 17th, and the point source was presumably detected at the afterglow candidate position reported by Yang et al. (GCN 35083). Here we report the Rc-band magnitudes and the 3-sigma limits of the stacked images as follows.

T0+[hour] | MID-UT | T-EXP[sec] | magnitudes of forced-photometry | 3-sigma limits
6.38 | 2023-11-17 09:25:57 | 5160 | Rc=20.7+/-0.3 | g'>20.5, Rc>20.4, Ic>19.8
7.59 | 2023-11-17 10:38:29 | 10320 | Rc=20.7+/-0.2 | g'>20.8, Rc>20.7, Ic>20.1
T0+ : Elapsed time after the trigger
T-EXP: Total Exposure time
These magnitudes include the contribution from the underlying host galaxy.

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;

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