GCN Circular 9531
Subject
GRB090618 - Continued optical monitoring and light curve break
Date
2009-06-19T08:56:19Z (16 years ago)
From
Zach Cano at ARI/John Moores Liverpool <zec@astro.livjm.ac.uk>
Z. Cano (Liverpool JMU), C. Guidorzi (U. Ferrara), D. Bersier,
A. Melandri, I.A. Steele, R.J. Smith, C. Mundell (Liverpool JMU)
report, on behalf of a large collaboration:
Following our report of observations (GCN 9520) we continued monitoring
the field of GRB090618 (Swift trigger 355083) on the Liverpool Telescope
(La Palma) from 13.6 hours to 17.9 hours post burst in R and i bands.
Below is a summary of a few R-band images:
t_exp t-T0 R-mag
300s 13.6 hours 18.9 � 0.1
300s 15.6 hours 19.1 � 0.1
300s 17.9 hours 19.3 � 0.1
The calibration is still preliminary and determined against stars in
the USNO catalog.
We note a break in the R-band light curve, and find a decay index of
alpha~1.4 by 17.9 hours post burst, as compared to alpha~0.7 previously
reported (GCNs 9517, 9520).