TITLE:   GCN CIRCULAR
NUMBER:  29547
SUBJECT: GRB210222B: LCO Optical Afterglow Detection
DATE:    21/02/22 23:42:26 GMT
FROM:    Robert Strausbaugh at U. of the Virgin Islands  <robert.strausbaugh@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 210222B (Gropp et al., GCN 29545) with the LCO 1-m Sinistro instrument at the Sutherland, South Africa site, on February 22, from 22:53 to 23:06 UT (corresponding to 0.27 to 0.43 hours from the GRB trigger time) with the Bessel R and I filters.

We performed a series of 3x120s exposures in R and I. We clearly detect an optical source in R and I band in stacked images at a location consistent with the initial UVOT detection (Gropp at al., GCN 29444); this source is not present in either USNO or 2MASS catalogs.  Using the USNO-B.1 catalog as reference, we calculate the following magnitudes:

R = 16.95 +/- 0.01

I = 16.32 +/- 0.01

These magnitudes are not corrected for galactic extinction.

R.S. is funded by NSF AST grant #1831682