[vsnet-grb-info 24860] GRB 200131A: LCO Optical Detection

[GCN Circulars]

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  <robert.strausbaugh at uvi.edu>

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.