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GCN Circular 20920

GRB 170317A: RATIR Optical and NIR Observations
2017-03-19T15:18:09Z (7 years ago)
Alan M. Watson at Instituto de Astronomia UNAM <>
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), Jes��s Gonz��lez (UNAM), Carlos Rom��n-Z����iga (UNAM), Harvey
Moseley (GSFC), John Capone (UMD), V. Zach Golkhou (ASU), and Vicki Toy
(UMD) report:

We observed the field of GRB 170317A (LaPorte et al., GCN 20885) with
the Reionization and Transients Infrared Camera (RATIR;
on the 1.5m Harold Johnson Telescope at the Observatorio Astron��mico
Nacional on Sierra San Pedro M��rtir from 2017/03 19.13 to 2017/03 19.30
UTC (41.26 to 45.37 hours after the BAT trigger), obtaining a total of
2.84 hours exposure in the r and i bands and 1.19 hours exposure in the
Z, Y, J, and H bands.

For a source within the enhanced Swift-XRT error circle (Beardmore et
al., GCN 20887), in comparison with the USNO-B1 and 2MASS catalogs, we
obtain the following detections and 3-sigma upper limits:

 r	23.70 +/- 0.10
 i	23.93 +/- 0.26
 Z	> 23.07
 Y	> 22.51
 J	> 22.27
 H	> 21.75

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

The source has faded by about a magnitude in r and i since our earlier
observations (Watson et al., GCN 20911).

We thank the staff of the Observatorio Astron��mico Nacional in San Pedro
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