TITLE:   GCN CIRCULAR
NUMBER:  39250
SUBJECT: GRB 250207A: 1.3m DFOT Optical observations
DATE:    25/02/09 14:25:06 GMT
FROM:    Amit Kumar Ror at ARIES <mitturor77894@gmail.com>

Amit K. Ror, Anshika Gupta, Kiran, Shashi B. Pandey, Kuntal Mishra (ARIES)
report:

We observed the field of GRB 250207A detected by the Swift Burst Alert
Telescope (Swift team, Ferro et al. 2025; GCN 39182) 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 2025-02-07 at 13:41:42 UT,
i.e., ~ 0.52 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 detected an optical afterglow in our stacked
image within the error box of the enhanced Swift-XRT position by Osborne et
al. 2025 (GCN 39217). We obtain the following preliminary magnitude in the
stacked image:

Date Start_UT T_start-T0 (days) Filter  Exp time (s)  Magnitude
=========================================================
2025-02-07 13:41:42     ~0.52     R     300s*4     21.12 +/- 0.15

Our detection is consistent with Angulo et al. 2025 (GCN 39186); Kuin et
al. 2025 (GCN 39199); Brivio et al. 2025 (GCN 39202); Jelinek et al. 2025
(GCN 39209) and Ferro et al. 2025 (GCN 39212).

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.