TITLE:   GCN CIRCULAR
NUMBER:  30973
SUBJECT: GRB 211023B: RATIR Optical and NIR Upper Limits 
DATE:    21/10/24 14:34:57 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), Eleonora Troja (GSFC), 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 (UMD), and Océlotl López (UNAM) report:

We observed the field of GRB 211023B (Dichiara et al., GCN 30960) 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 2021/10 24.49 to 2021/10 24.53 UTC (14.54 to 15.54 hours after the BAT
trigger), obtaining a total of 0.73 hours exposure in the r and i bands and 0.30
hours exposure in the Z, Y, J, and H bands.

For a source within the UVOT error circle, in comparison with the SDSS DR9 and
2MASS catalogs, we obtain the following detections and upper limits (3-sigma):

  r	> 22.4
  i	> 22.1
  Z	> 20.6
  Y	> 20.3
  J	> 21.0
  H	> 20.7

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.