[vsnet-grb-info 19109] GRB 170208B: RATIR Optical and NIR Observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  20655
SUBJECT: GRB 170208B: RATIR Optical and NIR Observations
DATE:    17/02/09 23:48:46 GMT
FROM:    Nat Butler at Az State U  <natbutler at asu.edu>

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), Eleonora
Troja (GSFC), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz (UCSC), 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 170208B (Siegel, et al., GCN 20632) 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 9.11 to 2017/02 9.47 UTC (3.98 to
12.65 hours after the BAT trigger), obtaining a total of 6.02 hours
exposure in the r and i bands and 2.52 hours exposure in the Z and Y bands.

We do not detect either the GROND (Kruehler, et al., GCN 20640) source or
the WHT (Wiersema, et al., GCN 20647) source.  In comparison with the
USNO-B1 and 2MASS catalogs, we obtain the following upper limits (3-sigma):

r > 23.56
i > 23.43
Z > 22.64
Y > 22.55

These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB.  The lack of detection of the WHT
source is consistent with this source being reddened due to dust or due to
a high-z origin if the GROND source is not the GRB host galaxy.  The first
possibility is also suggested by the significant X-ray column density
relative to the Galactic value (Kennea, et al., GCN 20637).

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