GCN Circular 41911
Subject
GRB250920C: LCOGT Optical Detection
Event
Date
2025-09-20T17:10:36Z (3 days ago)
From
Robert Strausbaugh at Eastern Illinois University <rstrausbaugh@eiu.edu>
Via
email
R. Strausbaugh (Eastern Illinois University), A. Cucchiara (NASA) report on behalf of a larger collaboration:
We observed the Swift GRB 250920C field (Gupta et al., GCN 41904) with the LCOGT 1-meter Sinistro instrument at the Siding Spring Observatory, Australia site, on September 20, from 16:29 to 16:51 UT (corresponding to 1.07 to 1.26 hours after the GRB trigger time) with the SDSS r and i filters.
We performed a series of 3x200s exposures in i-band and r-band. We detect an uncatalogued source consistent with GOTO optical counterpart candidate (Wortley et al., GCN 41907) in both bands.
The following magnitudes are calculated using the PanSTARRS catalog as reference:
r = 18.54 +/- 0.05
i = 18.25 +/- 0.01
These magnitudes are not corrected for galactic extinction.