TITLE:   GCN CIRCULAR
NUMBER:  41911
SUBJECT: GRB250920C: LCOGT Optical Detection
DATE:    25/09/20 17:10:36 GMT
FROM:    Robert Strausbaugh at Eastern Illinois University <rstrausbaugh@eiu.edu>

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.