GCN Circular 23017
Subject
GRB 180720B: COATLI Optical Detection
Date
2018-07-22T20:52:09Z (6 years ago)
From
Alan M. Watson at Instituto de Astronomia UNAM <alan@astro.unam.mx>
Alan M. Watson (UNAM), Nat Butler (ASU), Rosa L. Becerra (UNAM), William
H. Lee (UNAM), Carlos Rom��n-Z����iga (UNAM), Alexander Kutyrev (GSFC), and
Eleonora Troja (GSFC) report:
We observed the field of GRB 180720B (Siegel et al., GCN Circ. 22973)
with the COATLI 50-cm telescope and interim imager at the Observatorio
Astron��mico Nacional on the Sierra de San Pedro M��rtir
(http://coatli.astroscu.unam.mx) from 2018-07-22 06:25 to 11:23 UTC
(from 40.07 to 45.03 hours after the trigger), obtaining a total of 4.06
hours of exposure in the w filter.
We detect the optical counterpart (Martone et al., GCN Circ. 22976) with
w = 20.07 +/- 0.02
These magnitudes are calibrated against the USNO-B1 catalog (adjusted to
an approximate AB system) and are not corrected for Galactic extinction
in the direction of the GRB.
We thank the COATLI technical team (Fernando ��ngeles, Oscar Chapa,
Salvador Cuevas, Alejandro Farah, Jorge Fuentes, Rosal��a Langarica,
Fernando Quir��s, and Carlos Tejada) and the staff of the Observatorio
Astron��mico Nacional.