TITLE: GCN CIRCULAR NUMBER: 42810 SUBJECT: EP251118A: 3.6m DOT optical afterglow detection DATE: 25/11/23 04:45:13 GMT FROM: ANSHIKA GUPTA at ARIES anshika05180@gmail.com
Anshika Gupta, Pankaj Pawar, Dhruv Jain, Debolina Kar, and Kuntal Misra (ARIES) report:
We observed the field of EP251118A detected by Einstein Probe( Jiang et al. 2025, GCN 42749) 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 were started on 2025-11-22 at 04:57:21.74 UT, i.e., ~84.24 hours after the Einstein Probe trigger. We have taken multiple frames with an exposure time of 120 s in the r filter. We stacked the images after the alignment. We detect the optical counterpart in our stacked image within the error box of NOT (Malesani et al. 2025, GCN 42751). We obtain the following preliminary magnitude in the stacked image:
Date Start_UT T_start-T0 (hour) Filter Exp time (s) Magnitude ====================================================================== 2025-11-22 04:57:21.74 ~ 84.24 r 120s*9 22.33 +/- 0.18
Our detection is consistent with Malesani et al. 2025 (GCN 42751); Belkin et al. 2025 (GCN 42758); Yadav et al. 2025 (GCN 42760); Busmann et al. 2025 (GCN 42763); Francile et al. 2025 (GCN 42767); RodrÃguez et al. 2025 (GCN 42773); Li et al. 2025 (GCN 42776); Lee et al. 2025 (GCN 42780); Moskvitin et al. 2025 (GCN 42785); Gupta et al. 2025 (GCN 42787); Liu et al. 2025 (GCN 42793); Aryan et al. 2025 (GCN 42798).
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 Gaia catalog.
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