TITLE: GCN CIRCULAR NUMBER: 44271 SUBJECT: GRB260411B: 3.6m DOT optical observation DATE: 26/04/11 20:40:36 GMT FROM: ANSHIKA GUPTA at ARIES <anshika05180@gmail.com> Anshika Gupta, Aayushi Verma, Pankaj Pawar, Debalina Kar, Dhruv Jain, and Kuntal Misra (ARIES) report: We observed the field of GRB260411B detected by Fermi/GBM (Fermi GBM Team, GCN 44262) with the 3.6m Devasthal Optical Telescope (DOT), located at the Devasthal Observatory of the Aryabhatta Research Institute of Observational Sciences (ARIES), India. The observations began on 2026-04-11 at 20:29:45.480 UT, i.e., ~12.41 hours after the Fermi/GBM trigger. We have two frames with an exposure time of 200s in the r filter. We stacked the images after the alignment. We detect an optical counterpart in our stacked image at the position given by O'Neill et al. (GCN 44265). We obtain the following preliminary magnitude in the stacked image: Date Start_UT T_start-T0 (hours) Filter Exp time (s) Magnitude ================================================================== 2026-04-11 20:29:45.480 ~12.41 r 200s*2 19.74 +/-0.01 Our detection is consistent with O'Neill et al. (GCN 44265). 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 Pan-STARRS catalog. View this GCN Circular online at https://gcn.nasa.gov/circulars/44271. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...