[AAVSO-HEN] Optical observations of GRB 090618

[grb at aavso.org]

The following is a GCN Circular circulated via the AAVSO network.
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TITLE:   GCN CIRCULAR
NUMBER:  9519
SUBJECT: Optical observations of GRB 090618
DATE:    09/06/18 12:37:13 GMT
FROM:    Alberto Carraminana at AzTEC  <alberto at inaoep.mx>

A. Carraminana (INAOE), C. Alvarez Ochoa (UNACh)
and G. Miramon (OAGH-INAOE) report:

We clearly detected the optical counterpart of GRB 090618 (GCN 9512)
with the 2.1m telescope of the Observatorio Astrofisico
Guillermo Haro at Cananea, Sonora, Mexico. Observations started
at 08:43 UT, 14 minutes after the BAT trigger and continued
until dawn. Observations were made under non photometric conditions.

We measured a lineal faddening of the burst compared to
a reference star of amplitude 0.5 magnitudes between t=870s
to 1600s. A non calibrated graph is available at

http://www.inaoep.mx/~alberto/gamma/grb090618_lc.jpg

Spectroscopic data were also obtained and are under analysis.