TITLE:   GCN CIRCULAR
NUMBER:  21757
SUBJECT: LIGO/Virgo G299232 : RATIR Optical and NIR Observations of Swift UVOT source
DATE:    17/08/29 21:43:33 GMT
FROM:    Nat Butler at Az State U  <natbutler@asu.edu>

Nat Butler (ASU), Alan M. Watson (UNAM), V. Zach Golkhou (University of
Washington), Alexander Kutyrev (GSFC), William H. Lee (UNAM), Eleonora
Troja (GSFC), and Carlos Román-Zúñiga (UNAM) report:

We observed the field of Swift UVOT source (Emery et al., GCN 21733) 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 2017/08 29.24 to 2017/08 29.50 UTC (4 days
after GW trigger G299232), obtaining a total 1.8 hours exposure in the g
and r bands, 3.7 hours exposure in the i band, and 1.6 hours exposure in
the Z, Y, J, and H bands.

For a source within the UVOT error circle, in comparison with the SDSS DR9
and 2MASS catalogs, we obtain the following upper limits (3-sigma):

 g > 24.32
 r > 24.09
 i > 24.35
 Z > 23.07
 Y > 22.77
 J > 22.41
 H > 22.04

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

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