TITLE: GCN CIRCULAR NUMBER: 32898 SUBJECT: GRB 221028A: 1.3m DFOT Optical upper limit DATE: 22/10/31 07:20:02 GMT FROM: Amit Kumar Ror at ARIES mitturor77894@gmail.com
Amit Kumar Ror, Snehlata, Rahul Gupta, S. B. Pandey, Amar Aryan, Ankur Ghosh, Dimple, and Kuntal Misra (ARIES) report:
We observed Swift-BAT detected GRB 221028A (Lien et al. GCN 32874) using the 2Kx2K CCD Imager mounted on the 1.3m Devasthal Fast Optical Telescope (DFOT) located at the Devasthal observatory of Aryabhatta Research Institute of Observational Sciences (ARIES), India. The observations were started on 2022-10-28 at 15:17:46, i.e., around 2 hours after the BAT trigger. We have taken multiple frames, each having an exposure time of 300 sec in the R filter. We did not detect any new source within the XRT error circle in our stacked image. We obtain the following 3-sigma upper limit in the stacked image.
Date Start (UT) T_start-T0 (hours) Filter Exp time (sec) Limiting magnitude
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2022-10-28 15:17:46 ~2 R 300x6 > 21.5
The magnitude is not corrected for the Galactic extinction in the direction of the burst. Photometric calibration is performed using the standard stars from the USNO-B1.0 catalog.
The non-detection of the optical afterglow is consistent with Kumar et al. GCNs 32876, 32886; Hu et al. GCN 32878; Lipunov et al. GCN 32879; Strausbaugh et al. GCN 32881; Niwano et al. GCN 32883; Watson et al. GCN no. 32888; Belkin et al. GCN 32889; Odeh GCN 32894; and Komesh et al. GCN 32897.
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