TITLE:   GCN CIRCULAR
NUMBER:  31882
SUBJECT: GRB 220412A: RATIR Afterglow Candidate 
DATE:    22/04/12 07:25:10 GMT
FROM:    Alan M Watson at UNAM  <alan@astro.unam.mx>

Alan M. Watson (UNAM), Eleonora Troja (UTV), Nat Butler (ASU), Alexander
Kutyrev (GSFC), William H. Lee (UNAM), Michael G. Richer (UNAM), Ori Fox
(STScI), J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Enrico Ramirez-Ruiz
(UCSC), Jesús González (UNAM), Carlos Román-Zúñiga (UNAM), Harvey Moseley
(GSFC), Rosa L. Becerra (UNAM), Simone Dichiara (PSU), and Océlotl López (UNAM)
report:

We observed the field of GRB 220412A (Klingler et al. GCN 31881) 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 2022/04 12.28 to 2022/04 12.29 UTC (0.1 to 0.5 hours after the BAT
trigger), obtaining a total of 0.21 hours exposure in the r and i bands and 0.08
hours exposure in the Z, Y, J, and H bands.

We detect a bright, uncataloged source at RA = 123.967275 and declination =
30.342693 degrees (J2000), about 5.5 arcsec to the east of the current Swift XRT
SPER position. In comparison with the SDSS DR9 and 2MASS catalogs, we obtain the
following magnitudes:

   r = 19.41 +/- 0.12
   i = 19.26 +/- 0.10
   Y = 19.11 +/- 0.23

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

Despite being slightly outside the current XRT error region, we suggest that
this source is likely to be the afterglow. Observations are continuing.

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