[AAVSO-HEN] GRB 071010: TAROT La Silla observatory photometry of the afterglow

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TITLE:   GCN CIRCULAR
NUMBER:  6863
SUBJECT: GRB 071010: TAROT La Silla observatory photometry of the afterglow
DATE:    07/10/10 07:35:34 GMT
FROM:    Alain Klotz at CESR-CNRS  <Alain.Klotz at free.fr>

Klotz, A. (CESR-OMP), Boer M. (OHP), Atteia J.L. (LATT-OMP) report:

We derived accurate photometry of the afterglow
of GRB 071010 (cf. Klotz et al. GCNC 6860) from
TAROT, R and unfiltered images. We converted unfiltered
magnitudes into R band using a simple offset
assuming a low redshift (z<2) and a continuum
spectrum as described by Bloom et al. (GCNC 6861).

The afterglow is fainter than previously annonced
in GCNC 6860. We observed a rise of brightness
at a rate alpha=-0.9 (+/-0.5) until
about 470s after the trigger (+/-60s)
with a maximum brightness R=17.0.

Then the afterglow has decreased at a rate
alpha=+0.8 (+/-0.1) until at less 90 minutes
after the trigger (R=19.1 at t_trig+90min).
Observations are now finished in Chile due to
the set of the GRB.

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