TITLE: GCN CIRCULAR NUMBER: 26959 SUBJECT: GRB 200131A: LCO Optical Detection DATE: 20/02/01 05:13:29 GMT FROM: Robert Strausbaugh at U. of the Virgin Islands R. Strausbaugh (U. of the Virgin Islands), A. Cucchiara (U. of the Virgin Islands/College of Marin) report on behalf of a larger collaboration: We observed Swift GRB 200131A (Kennea et al., GCN 26953) with the LCO 1-m Sinistro instrument at the McDonald Observatory, Texas, USA site on January 31, from 01:59 to 02:22 UT (corresponding to 3.1 to 3.6 hours after the GRB trigger time) with the Bessel R and I filters. We performed a series of 5x120s exposures in each band. We detect a source in the Swift-BAT refined error region (Evans et al., GCN 26956) that is not present in either USNO-B1.0 or 2MASS surveys with the following magnitudes: R = 19.75 +/- 0.13 I = 19.31 +/- 0.14 This flux measurement is calibrated against several USNO-B1.0 objects near the GRB location and is not corrected for Galactic Extinction.