TITLE:   GCN CIRCULAR
NUMBER:  19391
SUBJECT: GRB 160504A: RATIR Optical and NIR Observations
DATE:    16/05/05 19:17:33 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 (GSFC/STScI),
Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz (UCSC),
José A. de Diego (UNAM), Leonid Georgiev (UNAM), Jesús González (UNAM),
Carlos Román-Zúñiga (UNAM), Neil Gehrels (GSFC), Harvey Moseley (GSFC),
John Capone (UMD), V. Zach Golkhou (ASU), and Vicki Toy (UMD) report:

We observed the field of GRB 160504A (Malesani, et al., GCN 19382) 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 2016/05 5.21 to 2016/05 5.36 UTC (19.64 to
23.11 hours after the BAT trigger), obtaining a total of 2.49 hours
exposure in the r and i bands and 1.04 hours exposure in the Z, Y, J, and H
bands.

For a source within the Swift-XRT error circle (Goad, et al., GCN 19386),
in comparison with the SDSS DR9 and 2MASS catalogs, we obtain the following
detection and upper limits (3-sigma):

 r > 23.70
 i = 23.62 +/- 0.36
 Z > 22.38
 Y > 22.08
 J > 21.73
 H > 21.35

These magnitudes, which appear to be consistent with those reported by
Cenko et al., (GCN 19389), 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.