TITLE:   GCN CIRCULAR
NUMBER:  20681
SUBJECT: GRB170214A: RATIR Optical and NIR Observations
DATE:    17/02/15 21:59:15 GMT
FROM:    Eleonora Troja at GSFC  <eleonora.troja@nasa.gov>

Eleonora Troja (GSFC), 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),
Antonino Cucchiara (UVI), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz
(UCSC), Jesús González (UNAM), Carlos Román-Zúñiga (UNAM), Harvey
Moseley (GSFC), John Capone (UMD), V. Zach Golkhou (ASU), and
Vicki Toy (UMD) report:


We observed the field of GRB 170214A (Mailyan, et al., GCN 20675;
Racusin, et al., GCN 20676) 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 2017/02 15.44 to 2017/02 15.50 UTC (10.58 to 11.99 hours
after the GBM trigger). We performed a series of tiled observations
partially covering the LAT error circle, obtaining a total of 0.40
hours exposure in the r and i bands and 0.32 hours exposure in the Z
and Y bands.

At the position of the first Swift/XRT source (source 1; Beardmore,
et al., GCN 20679), in comparison with the SDSS DR9 and 2MASS catalogs,
we obtain the following detections:

   r    21.06 +/- 0.11
   i    20.89 +/- 0.13
   Z    20.54 +/- 0.18
   Y    20.34 +/- 0.32

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

We did not detect any significant fading during our observations, so
at present we cannot confirm the nature of this source. Further
observations are planned.

The second, fainter XRT source (source 3; Beardmore, et al., GCN 20679)
falls outside our set of frames.

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