TITLE:   GCN CIRCULAR
NUMBER:  26882
SUBJECT: GRB 200125A: RATIR Optical Observations 
DATE:    20/01/26 01:39:15 GMT
FROM:    Alan M Watson at UNAM  <alan@astro.unam.mx>

Alan M. Watson (UNAM), Nat Butler (ASU), Alexander Kutyrev (GSFC),
William H. Lee (UNAM), Michael G. Richer (UNAM), Ori Fox (STScI), J.
Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (UVI),
Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz
(UCSC), Jesús González (UNAM), Carlos Román-Zúñiga (UNAM), Harvey
Moseley (GSFC), John Capone (UMD), V. Zach Golkhou (U. Wash.), and Vicki
Toy (UMD) report:

We observed the field of GRB 200125A (Lien et al., GCN Circ. 26876) with
the Reionization and Transients Infrared Camera (RATIR; www.ratir.org)
on the 1.5m Harold Johnson Telescope at the Observatorio Astronómico
Nacional on Sierra San Pedro Mártir from 2020/01 25.48 to 2020/01 25.56
UTC (0.03 to 1.89 hours after the BAT trigger), obtaining a total of
1.40 hours exposure in the r and i bands.

We detect a a source within the enhanced Swift-XRT error circle
(Beardmore et al., GCN Circ. 26878). In comparison with the USNO-B1 and
2MASS catalogs, we obtain the following detections:

  r	= 21.02 +/- 0.05
  i	= 19.54 +/- 0.02

These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB.

We thank the staff of the Observatorio Astronómico Nacional in San Pedro
Mártir.