TITLE:   GCN CIRCULAR
NUMBER:  18941
SUBJECT: GRB 160127A: RATIR Optical Observations
DATE:    16/01/27 15:16:55 GMT
FROM:    Alan M. Watson at Instituto de Astronomia UNAM  <alan@astro.unam.mx>

Antonino Cucchiara (GSFC/STScI), Nat Butler (ASU), Alan M. Watson
(UNAM), Alexander Kutyrev (GSFC), William H. Lee (UNAM), Michael G.
Richer (UNAM), Ori Fox (STScI), J. Xavier Prochaska (UCSC), Josh Bloom
(UCB), 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),
Harvey Moseley (GSFC), John Capone (UMD), V. Zach Golkhou (ASU), and
Vicki Toy (UMD) report:

We observed the field of GRB 160127A (Amaral-Rogers et al., GCN 18938)
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 2016/01 27.39 to
2016/01 27.55 UTC (0.73 to 4.43 hours after the BAT trigger), obtaining
a total of 2.68 hours exposure in the r,i and z bands.

We detect the optical counterpart at

RA, Dec = 15:3:55.77, +00:04:22.4 (J2000, +/-0.5”).

In comparison with the SDSS DR9, we obtain the following magnitudes:

 r	20.64 +/- 0.03
 i	20.66 +/- 0.03
 z	20.14 +/- 0.32

These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB.

Further observations are planned.

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