TITLE: GCN CIRCULAR NUMBER: 38815 SUBJECT: GRB 241228A: 1.3m DFOT upper limit DATE: 25/01/04 05:40:01 GMT FROM: Amit Kumar Ror at ARIES mitturor77894@gmail.com
Amit K. Ror, Anshika Gupta, Pranshu, Shashi B. Pandey, Kuntal Mishra (ARIES) report:
We observed the field of GRB 241228A detected by Swift (Swift Observatory Team, D'Elia et al. 2024, GCN 38681) with the 1.3m Devasthal Fast Optical Telescope (DFOT), located at the Devasthal Observatory of the Aryabhatta Research Institute of Observational Sciences (ARIES), India. The observations were started on 2024-12-30 at 13:16:07 UT, i.e., ~ 2.38 days after the Swift-BAT trigger. We have taken multiple frames with an exposure time of 300 s in the R filter. We stacked the images after the alignment. We could not detect the optical emission reported by Volnova et al. (2024, GCN 38709) in our stacked image within the error box enhanced Swift-XRT position (GCN 38683). We obtain the following 3-sigma upper limit in the stacked image:
Date Start_UT T_start-T0 (days) Filter Exp time (s) Magnitude
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2024-12-30 13:16:07 ~ 2.38 R 300s*12 >21.2
The non-detection of the burst is consistent with the upper limits reported by Kuin et al. 2024, GCN 38685; Mohan et al. 2024, GCN 38689; Lipunov et al. 2024, GCN 38693; Zhu et al. 2024, GCN 38703.
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 catalogue. This circular may be cited.
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