TITLE:   GCN CIRCULAR
NUMBER:  16174
SUBJECT: GRB 140423A: Continued RATIR Optical and NIR Observations
DATE:    14/04/25 22:10:59 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 140423A (Sonbas, et al., GCN 16142) 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 2014/04 25.15 to 2014/04 25.47 UTC (43.01 to
50.78 hours after the BAT trigger), obtaining a total of 4.07 hours
exposure in the r and i bands and 1.73 hours exposure in the Z, Y, J, and H
bands.

For a source within the Swift-UVOT error circle (Chester, et al., GCN
16147), in comparison with the SDSS DR9 and 2MASS, we obtain the following
detections and upper limit (3-sigma):

  r     22.70 +/- 0.11
  i     22.67 +/- 0.12
  Z     22.49 +/- 0.35
  Y     22.17 +/- 0.29
  J     > 21.66
  H     21.87 +/- 0.35

These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB.  Compared to our observations last
night (Littlejohns et al., GCN 16170), the source has faded approximately
as t^(-1.3).

We thank the staff of the Observatorio Astronómico Nacional in San Pedro
Mártir.