TITLE:   GCN CIRCULAR
NUMBER:  43665
SUBJECT: GRB 260208A: 1.3m DFOT optical detection
DATE:    26/02/09 11:24:07 GMT
FROM:    ANSHIKA GUPTA at ARIES <anshika05180@gmail.com>


Anshika Gupta, Kuntal Misra, Dhruv Jain, Pankaj Pawar, and Debalina Kar (ARIES) report:

We observed the field of GRB 260208A detected by (Fermi GBM team, GCN 43635; Sonawane et al. 2026, GCN 43642; Longo et al. 2026, GCN 43645; Dichiara et al. 2026, GCN 43652; Luo et al. 2026, GCN 43658) 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  2026-02-08 at 20:52:28 UT, i.e., ~ 15.75 hours after the Fermi/GBM trigger. We detect an optical afterglow in a single 300s R-band exposure at the position reported by (Podesta et al. 2026, GCN 43640). We obtain the following preliminary magnitude in the stacked image:

Date Start_UT T_start-T0 (hour) Filter  Exp time (s)  Magnitude
===============================================================
2026-02-08  20:52:28    ~15.75   R     300s*1     19.89 +/-0.04


The optical detection of the burst is consistent with Lipunov et al. 2026 (GCN 43637); Podesta et al. 2026 (GCN 43640); Wortley et al. 2026 (GCN 43641); Ma et al. 2026 (GCN 43655); Ahumada et al. 2026 (GCN 43657); and Dimple et al. 2026 (GCN 43661, 43662).

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.