TITLE:   GCN CIRCULAR
NUMBER:  42849
SUBJECT: GRB 251126A: Asiago i-band detection
DATE:    25/11/26 21:14:37 GMT
FROM:    Daniele Bjørn Malesani at Cosmic Dawn Center, Niels Bohr Institute <daniele.malesani@nbi.ku.dk>

A. Reguitti (INAF/OAPD), L. Tomasella (INAF/OAPD), D. B. Malesani (DAWN/NIB and Radboud), report on behalf of a larger collaboration:

We observed the optical afterglow (Swain et al., GCN 42844; Fu et al., GCN 42848) of GRB 251126A (Caputo et al., GCN 42843) using the 67/92 Schmidt Telescope located at the Asiago observatory (Italy). Observations were carried out using the Sloan i filter.

In a single exposure with start time 2025 Nov 26.8252 UT (37.8 min after the Swift/BAT trigger), the afterglow is detected with a magnitude i = 18.27 +- 0.15 (AB), calibrated against nearby stars fron the Pan-STARRS catalog, and not corrected for Galactic extinction.

Compared to the earlier optical measurements (Swain et al., GCN 42844; Fu et al., GCN 42848), our images seem to indicate a red r-i color for the optical afterglow.