[vsnet-grb-info 20518] GRB 180407A: COATLI Upper Limits

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  22614
SUBJECT: GRB 180407A: COATLI Upper Limits
DATE:    18/04/07 04:37:08 GMT
FROM:    Alan M. Watson at Instituto de Astronomia UNAM  <alan at astro.unam.mx>

Alan M. Watson (UNAM), Nat Butler (ASU), Rosa L. Becerra (UNAM), William
H. Lee (UNAM), Carlos Román-Zúñiga (UNAM), Alexander Kutyrev (GSFC), and
Eleonora Troja (GSFC), report:

We observed the field of GRB 180407A (Deich et al., GCN 22612) with the
COATLI 50-cm telescope and interim imager
(http://coatli.astroscu.unam.mx) at the Observatorio Astronómico
Nacional on the Sierra de San Pedro Mártir from 2018-04-07 02:26:12 to
03:01:38 (0.52 to 1.12 hours after trigger) obtaining a total of 510
seconds of exposure in the w filter.

The images were obtained at high airmass (above 3.1) and during
twilight.

For a source within the Swift/BAT error circle, in comparison with the
USNO-B1 catalog, we obtain the following 10-sigma upper limit:

w > 16.53

This magnitude is in the USNO system and is not corrected for Galactic
extinction in the direction of the GRB.

We thank the COATLI technical team (Fernando Ángeles, Oscar Chapa,
Salvador Cuevas, Alejandro Farah, Jorge Fuentes, Rosalía Langarica,
Fernando Quirós, and Carlos Tejada) and the staff of the Observatorio
Astronómico Nacional.


-- 
Dr. Alan M. Watson
Instituto de Astronomía
Universidad Nacional Autónoma de México