TITLE:   GCN CIRCULAR
NUMBER:  16136
SUBJECT: GRB 140419A: Continued RATIR Optical and NIR Observations
DATE:    14/04/21 01:18:52 GMT
FROM:    Owen Littlejohns at Az State U  <olittlej@asu.edu>

Owen Littlejohns (ASU), 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), 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 140419A (Marshall, et al., GCN 16118) 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 20.14 to 2014/04 20.29
UTC (23.23 to 26.83 hours after the BAT trigger), obtaining a total of
2.49 hours exposure in the r and i bands and 1.04 hours exposure in the Z,
Y, J, and H bands.

We continue to detect the UVOT optical transient (Zheng, et al., GCN 16116;
Guver et al., GCN 16120). For a source within the GCN-16119 error circle,
in comparison with the SDSS DR9 and 2MASS, we obtain the following
detections:

  r     21.35 +/- 0.04
  i     20.76 +/- 0.04
  Z     20.61 +/- 0.06
  Y     20.45 +/- 0.07
  J     20.35 +/- 0.08
  H     20.32 +/- 0.10

These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB. In comparison to the previous
epoch of RATIR observations (Butler, et al., GCN 16121) we find that the
source has continued to fade with an approximate power-law index of
alpha = 1.2 in all six bands.

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