GCN Circular 41932
Subject
GRB 250920B: Asiago optical observations
Event
Date
2025-09-21T17:57:22Z (9 days ago)
From
Daniele Bjørn Malesani at Cosmic Dawn Center, Niels Bohr Institute <daniele.malesani@nbi.ku.dk>
Via
email
A. Reguitti (INAF/OAPd), L. Tomasella (INAF/OAPd), D. B. Malesani
(DAWN/NBI and Radboud) report on behalf of a larger collaboration:
We observed the field of GRB 250920B (Gupta et al., GCN 41898; Sonawane
& Meegan, GCN 41919) using the 67/92 Schmidt Telescope located at the
Asiago observatory (Italy). Observations were carried out using a clear
filter, which covers roughly the r and i bands.
The optical counterpart (Gupta et al., GCN 41898; Wu et al., GCN 41908;
Hall et al., GCN 41914; Kuin & Gupta, GCN 41915) is well detected in our
frames. At a mean epoch 2025 Sep 20.771 UT (9.74 hr after the GRB), we
measure an AB magnitude r = 18.62 +- 0.06 (calibrated directly against
r-band magnitudes from the Pan-STARRS catalog).
Considering the filter difference, our measurement is consistent with
the nearly simultaneous observation by Hall et al. (GCN 41914).