TITLE:   GCN CIRCULAR
NUMBER:  14459
SUBJECT: GRB 130427A: RATIR Optical and NIR Observations
DATE:    13/04/27 13:30:44 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), Chris Klein (UCB), Ori Fox (UCB)
J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (UCSC),
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), and Harvey Moseley (GSFC)
report:

We observed the field of GRB 130427A (Maselli, et al., GCN 14448) 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 2013/04 27.34 to 2013/04 27.39 UTC (0.25 to
1.67 hours after the BAT trigger), obtaining a total of 1.07 hours exposure
in the r' and i' bands and 0.45 hours exposure in the Z, Y, J, and H bands.

For a source at afterglow location reported by Elenin et al. (GCN 14450),
in comparison with SDSS DR8 and 2MASS, we obtain the following detections:

  i' 14.46 +/- 0.01
  Z  14.13 +/- 0.03
  Y  14.02 +/- 0.03
  J  14.05 +/- 0.02
  H  13.77 +/- 0.03

These magnitudes 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.