TITLE:   GCN CIRCULAR
NUMBER:  15752
SUBJECT: GRB 140118A: RATIR Optical and NIR Observations
DATE:    14/01/18 15:48:58 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
(ORAU/GSFC), 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 140118A (Krimm, et al., GCN 15748) 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 2014/01 18.09 to 2014/01 18.10 UTC (39.6 to
53.4 minute after the BAT trigger), obtaining a total of 7.8 minutes
exposure in the r and i bands and 4.2 minutes exposure in the Z, Y, and J
bands through high airmass.

We detect no new, uncatalogued sources in the refined Swift BAT error box
(Lien et al., GCN 15750).  In comparison with 2MASS, we obtain the
following 3-sigma upper limits:

  r     > 19.93
  i     > 19.37
  Z     > 19.06
  Y     > 18.99
  J     > 18.32

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.