TITLE:   GCN CIRCULAR
NUMBER:  30484
SUBJECT: GRB 210722A: RATIR Optical Observations
DATE:    21/07/23 14:49:14 GMT
FROM:    Nat Butler at Az State U  <natbutler@asu.edu>

Nat Butler (ASU), Alan M. Watson (UNAM), 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 210722A (D'Avanzo, et al., GCN 30475) with the
Reionization and Transients Infrared Camera (RATIR) on the 1.5m Harold
Johnson Telescope at the Observatorio Astronómico Nacional on Sierra San
Pedro Mártir from 2021/07 23.40 to 2021/07 23.48 UTC (12.43 to 14.36 hours
after the BAT trigger), obtaining a total of 1.22 hours exposure in the r
and i bands.

In comparison with the SDSS DR9 and 2MASS catalogs, we obtain the following
detections of the optical afterglow:

  r = 19.41 +/- 0.05
  i = 19.35 +/- 0.04

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.