TITLE:   GCN CIRCULAR
NUMBER:  27456
SUBJECT: GRB 200325B: LCO Optical Detection
DATE:    20/03/27 15:26:37 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 Fermi GRB 200325A (Fermi GBM Team, GCN 27441) with the LCO 1-m Sinistro instrument at the Siding Spring Observatory, Australia site, on March 27, from 12:08 to 12:48 UT (corresponding to 45.25 to 45.92 hours from the GRB trigger time) with the Bessel R and I filters.

We performed a series of 5x240s exposures in R and I.  We detect a source consistent with other optical detections (Lipunov et al., GCN 27446, Pozanenko et al., GCN 27452) in stacked images.  Using the USNO-B.1 catalog as reference, we obtain the following magnitudes:

R = 21.36 +/- 0.11

I = 20.52 +/- 0.13

These magnitudes are not corrected for Galactic Extinction.

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