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 Rom��n-Z����iga (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 Astron��mico Nacional
on Sierra San Pedro M��rtir 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 Astron��mico Nacional in San Pedro
M��rtir.