GCN Circular 42043
Subject
GRB 251001B: LCOGT Optical Observations
Event
Date
2025-10-01T15:44:16Z (25 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 251001B field (Beardmore et al., GCN 42039) with the LCOGT 1-meter Sinistro instrument at the Siding Spring Observatory, Australia site, on October 1, from 14:51 to 15:23 UT (corresponding to 0.57 to 1.10 hours after the GRB trigger time) with the SDSS i and r filters.
We performed a series of 3x300s exposures in i-band and r-band. We detect an uncatalogued source consistent with other optical counterpart observations (Gompertz et al., GCN 42040; An et al., GCN 42041) in both bands. We note that our r-band measurement implies a rapidly fading source.
The following magnitudes are calculated using the PanSTARRS catalog as reference:
r = 20.26 +/- 0.04
i = 19.81 +/- 0.03
These magnitudes are not corrected for galactic extinction.