TITLE:   GCN CIRCULAR
NUMBER:  22011
SUBJECT: GRB 171010A: RATIR Optical and NIR Observations 
DATE:    17/10/13 17:29:22 GMT
FROM:    Alan M. Watson at Instituto de Astronomia UNAM  <alan@astro.unam.mx>

Alan M. Watson (UNAM), Eleonora Troja (GSFC), Nat Butler (ASU),
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 (U. Wash.), and Vicki
Toy (UMD) report:

We observed the field of GRB 171010A (Omodei et al., GCN Circ. 21985)
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 2017/10 13.33 to
2017/10 13.50 UTC (60.79 to 65.05 hours after the LAT trigger),
obtaining a total of 2.72 hours exposure in the r and i bands and 1.13
hours exposure in the Z, Y, J, and H bands.

We detect the afterglow candidate reported by Thorstensen & Halpern (GCN
Circ. 21987), Izzo & Malesani (GCN Circ. 21988), and D'Ai et al. (GCN
Circ. 21989). In comparison with the USNO-B1 and 2MASS catalogs, we
obtain the following magnitudes:

  r = 19.88 +/- 0.02
  i = 19.59 +/- 0.02 
  Z = 19.25 +/- 0.02
  Y = 19.19 +/- 0.02
  J = 18.97 +/- 0.03
  H = 18.80 +/- 0.03

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

Further observations are planned.

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