Eleonora Troja (GSFC), 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), Owen Littlejohns (ASU), 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 130518A (Xiong, et al., GCN 14674; Omodei,
et al., GCN 14675) 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
from 2013/05 19.44 to 2013/05 19.47 UTC (20.54 to 21.49 hours after
the GBM trigger), obtaining a total of 0.64 hours exposure in the r'
and i' bands, 0.27 hours exposure in the Z and Y bands, and 0.15 hours
exposure in the J, and H bands.
We detect a new, uncatalogued source at RA,Dec = 355.66781, +47.46493
(J2000) with an uncertainty of 0.5 arcsec.
This position is 5 arcsec from the XRT localization, just outside the
XRT error circle (Evans, et al., GCN 14678). In comparison with SDSS DR8
and 2MASS, we obtain the following detections:
r' 19.38 � 0.02
i' 19.10 � 0.02
Z 18.83 � 0.04
Y 18.65 � 0.04
J 18.28 � 0.07
H 18.47 � 0.11
These magnitudes are in the AB system and not corrected for Galactic
extinction in the direction of the GRB. We have evidence at the 2-3 sigma
level of fading in r' and i' over the duration of our observations.
Further observations are planned.
We thank the staff of the Observatorio Astron�mico Nacional in San Pedro