[vsnet-grb-info 347] GRB020813: V-band decay slope

[GCN Circulars <gcncirc@lheawww.gsfc.nasa.gov>]

TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  1500
SUBJECT: GRB020813: V-band decay slope
DATE:    02/08/16 19:37:57 GMT
FROM:    Daniele Malesani at Obs.Astro. di Brera  <malesani@merate.mi.astro.it>

D. Malesani and S. Covino (INAF, Merate Obs., Milan), D. Fugazza and R.
Barrena (TNG), E. Pian and N. Masetti (IASF/CNR, Bologna), on behalf of
a larger collaboration, report:


We observed the optical counterpart of GRB 020813 on Aug 13.99, 15.04
and 16.03 UT, using the VLT and TNG telescopes and a standard Bessel V
filter. The source is clearly detected and it shows a fading by 1.04 +/-
0.05 magnitudes between the first and the second epoch, and by 0.62 +/-
0.10 magnitudes between the second and third epoch. The afterglow is
hence decaying with time according to a sharply defined power-law with a
slope of delta = -1.4 +/- 0.02.

The break in the decay suggested in GCN #1476 (Bloom, Fox & Hunt) and
#1491 (Li, Chornock & Filippenko) is therefore confirmed.

Complete analysis of the photometric data is underway.

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