TITLE: GCN CIRCULAR NUMBER: 39240 SUBJECT: GRB 250205A: 1.3m DFOT optical upper limit DATE: 25/02/08 17:27:46 GMT FROM: ANSHIKA GUPTA at ARIES anshika05180@gmail.com
Anshika Gupta, Amit K. Ror, Kuntal Misra and Shashi B. Pandey (ARIES) report:
We observed the field of GRB 250205A detected by SVOM/ECLAIRs (Saccardi et al. 2025, GCN 39154) 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 2025-02-06 at 17:00:56 UT, i.e., ~ 0.81 days after the SVOM 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 in our stacked image within the error box of SVOM telescope (Palmerio et al. 2025, GCN 39159) and Swift-XRT (Kennea et al. 2025, GCN 39161). We obtain the following 3-sigma upper limit in the stacked image:
Date Start_UT T_start-T0 (days) Filter Exp time (s) Magnitude ============================================================ 2025-02-06 17:00:56 ~0.81 R 300s*12 > 22.0
The non-detection of the burst is consistent with the GCN reported by Gompertz et al. GCN 39156, 39158; Schneider et al. GCN 39157; Palmerio et al. GCN 39159; de Ugarte Postigo et al. GCN 39160; Watson et al. GCN 39162; Breeveld et al. GCN 39168; Busmann et al. GCN 39169; Ferro et al. GCN 39170.
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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