GCN Circular 14212

Nat Butler (ASU), Antonino Cucchiara (UCSC), William H. Lee (UNAM),
Alexander Kutyrev (GSFC), Alan M. Watson (UNAM), Michael G. Richer (UNAM),
Chris Klein (UCB), Ori Fox (UCB) J. Xavier Prochaska (UCSC), Josh Bloom
(UCB), Eleonora Troja (GSFC), Enrico Ramirez���Ruiz (UCSC), Jos�� A. de Diego
(UNAM), Leonid Georgiev (UNAM), Jes��s Gonz��lez (UNAM), Carlos Rom��n-Z����iga
(UNAM), Neil Gehrels (GSFC), and Harvey Moseley (GSFC) report:

We observed the field of GRB 130215A (D'Elia et al.; GCN 14204
Not found
 
 
) with the
Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on the
1.5m Harold Johnson Telescope at the Observatorio Astron��mico Nacional on
Sierra San Pedro M��rtir from 2013/02 15.13 to 2013/02 15.18 UTC (1.58 to
2.88 hours after the BAT trigger) through intermittent clouds, obtaining a
total of 25 minutes of useful exposure in the r' and i' bands and 19
minutes of useful exposure in the Z and J bands.

We detect the optical counterpart discovered by ROTSE (Zheng et al.; GCN
14205
Not found
 
 
).   In comparison with USNO-B1 and 2MASS, we derive the following
magnitudes in the AB system:

  r' = 17.86 +/- 0.05
  i' = 17.10 +/- 0.04
  Z = 16.86 +/-0.04
  J = 16.67 +/- 0.04

These magnitudes are not corrected for Galactic extinction in the direction
of the GRB.  Compared to the earlier observation at Palomar (Cenko et al;
GCN 14209
Not found
 
 
), our r band magnitude implies a temporal fade by >1 mag on a
timescale of 2 hours, with a corresponding power law fade f ~ t^(-1.5)
between 1 and 3 hours after the GRB.

We thank the staff of the Observatorio Astron��mico Nacional in San Pedro
M��rtir.