TITLE:   GCN CIRCULAR
NUMBER:  20007
SUBJECT: GRB 160821A: Maisoncelles observatory optical observations
DATE:    16/10/06 23:05:54 GMT
FROM:    Alain Klotz at IRAP-CNRS-OMP  <Alain.Klotz@free.fr>

Soulier J.-F. (Observatoire de Maisoncelles, France) repports:

I imaged the field of GRB 160821A detected by SWIFT
(trigger 709351) with the Newtonian 30cm F/3.8 telescope
located at the Maisoncelles observatory, France (IAU C10).

I detected the optical transcient described by Gendre et al.
(GCNC 19832) at the following position (+/- 0.5 arcsec):

RA(J2000.0) = 11h 25m 01.83s
DEC(J2000.0) = +42d 20' 06.5"

Filter  T_start(d)   T_stop(d)  Exp(s)     R
None    0.992        1.008      1440       18.6
None    4.992        4.008      1440	  >20

Taking account for the magnitude provided by Gendre et al.
(GCNC 19832) I derived an optical decay alpha=0.78 for the
first day.

Magnitudes were estimated with the nearby UCAC-4 stars
and are not corrected for galactic dust extinction.