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 (U. Wash.), and Vicki
Toy (UMD) report:
We observed the field of GRB 180329B (Racusin et al., GCN 22558) 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 2018/03 30.13 to 2018/03 30.18
UTC (12.92 to 14.22 hours after the BAT trigger), obtaining a total of
0.96 hours exposure in the r and i bands.
For a source within the Swift-XRT error circle, in comparison with the
USNO-B1 catalog, we obtain the following detections:
r = 20.29 +/- 0.09
i = 20.32 +/- 0.10
These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB.
The source has faded in r at the 4-sigma level when compared to the
earlier NOT observation of Perley et al. (GCN 22562).
We thank the staff of the Observatorio Astron��mico Nacional in San Pedro