GCN Circular 22664
Subject
GRB 180418A: Continued RATIR Optical Observations
Date
2018-04-19T13:35:19Z (6 years ago)
From
Eleonora Troja at GSFC <eleonora.troja@nasa.gov>
Eleonora Troja (GSFC), 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), 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 re-observed the field of GRB 180418A (D'Elia, et al., GCN 22646) 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 2018/04 19.13 to 2018/04 19.41 UTC
(20.47 to 27.09 hours after the BAT trigger), obtaining a total of
4.17 hours exposure in the r and i bands.
The optical afterglow (Zheng & Filippenko, GCN 22647) is detected in all
bands and significantly faded with respect to our first night of
observations (Troja et al., GCN 22652). In comparison with the
SDSS DR9 catalog, we obtain the following detections:
�� r = 23.63 +/- 0.22
�� i = 23.14 +/- 0.16
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.