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GCN Circular 9809

GRB090814A: NOT optical follow-ups
2009-08-14T23:02:39Z (15 years ago)
Dong Xu at DARK,NBI <>
D. Xu, J.P.U. Fynbo (DARK/NBI), P. Jakobsson (Univ. Iceland), Tiina 
Liimets (NOT) report on behalf of a larger collaboration:

We observed the field of GRB 090814A (Ukwatta et al. GCN 9793; Updike et 
al., GCN 9794) with the Nordic Optical Telescope equipped with ALFOSC. 
We obtained 3x600 s R-band frames staring on August 14th,  21:15:11 UT, 
20.38 hr after the burst.

The optical afterglow is clearly detected in each frame. The magnitude 
is R~22.4 calibrated against the reference star, #1156-0231252 with 
R2=19.25,  of the USNO B1 catalog.

Compared with the previous measurement of R~21.5 around 70 mins after 
the burst (Jakobsson et al., GCN 9797), the afterglow is decaying quite 
shallowly, with a power-law slope of ~0.3, being consistent with the 
X-ray decaying law during the same period (Page & Ukwatta, GCN 9801).
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