TITLE:   GCN CIRCULAR
NUMBER:  46288
SUBJECT: GRB 261113A: R-band observations with the 1.3m DFOT
DATE:    26/11/15 06:59:22 GMT
FROM:    pawarpankaj1492@gmail.com

Pankaj Pawar, Divyanshu, Anshika Gupta, Debalina Kar, Dhruv Jain, Kuntal Misra, Yash Sharma, Amit K Ror and Shashi B. Pandey (ARIES, Nainital, India) report:

We observed the field of GRB 261113A (Saccardi et al., GCN 46244; Frederiks et al., GCN 46268; Dagoneau et al., GCN 46270; Zao et al., GCN 46287) with the 1.3m Devasthal Fast Optical Telescope (DFOT), India, on 2026 November 14. Observations began at 13:28:56 UT. We obtained six 300-s exposures in the R filter. The reported redshift is z = 3.580 (Saccardi et al., GCN 46261; Perez-Garcia et al., GCN 46264).

We reduced and stacked the images using standard procedures. Forced PSF photometry at the reported optical afterglow position (Lei et al., GCN 46248; Li et al., GCNs 46249, 46254; Yin et al., GCN 46250; Chen et al., GCN 46251; Wu et al., GCN 46252; Zhao et al., GCN 46253; Saikia et al., GCN 46256; Adami et al., GCN 46257; Gress et al., GCN 46258; Izzo et al., GCN 46259; Maksut et al., GCN 46262; Moskvitin et al., GCNs 46263, 46279; de Ugarte Postigo et al., GCN 46265; Dimple et al., GCN 46266; Jelinek et al., GCN 46271; Wei et al., GCN 46274; Xu, GCN 46280; also observed in the NIR by Lin et al., GCN 46247, and Brivio et al., GCN 46260) gives the following tentative measurement:

Mid-time (UT)          Tmid-T0 (d)   Filter   Exposure (s)     Mag (Vega)
2026-11-14 13:44:08     0.96743       R        6 x 300        22.77 +/- 0.37

T0 is 2026-11-13 14:31:02 UT (Saccardi et al., GCN 46244). Photometry
was calibrated against nearby Pan-STARRS DR2 stars transformed to
Cousins R using Kostov & Bonev (2018, Bulgarian Astronomical Journal,
28). The magnitude is on the Vega system and is not corrected for
Galactic extinction.