TITLE:   GCN CIRCULAR
NUMBER:  24282
SUBJECT: GRB 190427A: RATIR Optical and NIR Observations
DATE:    19/04/27 14:08:29 GMT
FROM:    Eleonora Troja at NASA/GSFC/UMD  <eleonora@umd.edu>

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), Jesús González (UNAM), Carlos Roman-Zuniga (UNAM),
Harvey Moseley (GSFC), John Capone (UMD), V. Zach Golkhou (U. Wash.),
and Vicki Toy (UMD) report:

We observed the field of GRB 190427A (Tohuvavohu, et al., GCN 24261)
with the Reionization and Transients Infrared Camera (RATIR;
www.ratir.org) on the 1.5m Harold Johnson Telescope at the Observatorio
Astronomico Nacional on Sierra San Pedro Martir from 2019/04 27.28 to
2019/04 27.30 UTC (2.22 to 2.53 hours after the BAT trigger), obtaining
a total of 0.20 hours exposure in the r and i bands and 0.06 hours
exposure in the Z, Y, J, and H bands.

In comparison with the SDSS DR9 catalog, we detect no new source brighter
than r~22 AB mag within the BAT error circle.

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