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GCN Circular 23094

GRB 180806A/180806.94: Refined COATLI Photometry of MASTER OT J004613.05+242014.1
2018-08-07T16:02:35Z (6 years ago)
Alan M. Watson at Instituto de Astronomia UNAM <>
Nat Butler (ASU), Alan M. Watson (UNAM), 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 the MASTER OT J004613.05+242014.1 (Lipunov et
al., GCN Circ. 23091), possibly associated with GRB 180806A/180806.94
(Fermi trigger 555287944), with the COATLI 50-cm telescope and interim
imager at the Observatorio Astron��mico Nacional on the Sierra de San
Pedro M��rtir ( from 2018-08-07 11:23:26
UTC to 12:21:39 UTC (12.74 to 13.71 hours after trigger), obtaining a
total of 2730 seconds of exposure in the w filter.

We detect a source coincident with the reported coordinates of the OT
(Lipunov et al., GCN Circ. 23091) with

w = 20.22 +/- 0.05

This magnitude is calibrated against the USNO-B1 catalog (adjusted to an
approximate AB system) and is not corrected for Galactic extinction in
the direction of the GRB.

This photometry supersedes that reported by Watson et al. (GCN 23092).

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.
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