GCN Circular 21303
Subject
GRB 170705A: Further RATIR Optical and NIR Observations and Steepening of Fading
Date
2017-07-06T18:37:15Z (7 years ago)
From
Alan M. Watson at Instituto de Astronomia UNAM <alan@astro.unam.mx>
Alan M. Watson (UNAM), 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), 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 170705A (Starling et al., GCN Circ. 21289) 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 2017/07 6.17 to 2017/07 6.26 UTC (25.33
to 27.52 hours after the BAT trigger), obtaining a total of 1.02 hours
exposure in the r and i bands and 0.37 hours exposure in the Z,
Y, J, and H bands.
For a source within the Swift-XRT error circle, in comparison with the SDSS DR9 and 2MASS catalogs, we obtain the following detections:
r = 20.62 +/- 0.05
i = 20.35 +/- 0.05
Z = 19.68 +/- 0.07
Y = 19.72 +/- 0.09
J = 19.46 +/- 0.10
H = 19.61 +/- 0.16
These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB.
The source has faded on average by 1.90 +/- 0.17 magnitudes compared to our previous observations (Butler et al., GCN Circ. 21293). This corresponds to a temporal index of -0.72 +/- 0.03, which is steeper than the index of -0.4 we saw during our previous observations.
We thank the staff of the Observatorio Astron��mico Nacional in San Pedro
M��rtir.