[vsnet-grb-info 7866] GRB 090519: NOT refined analysis

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  9410
SUBJECT: GRB 090519: NOT refined analysis
DATE:    09/05/20 14:53:33 GMT
FROM:    Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst  <malesani at astro.ku.dk>

D. Malesani (DARK/NBI), C.C. Thoene (INAF/Brera), P. Jakobsson (Univ. 
Iceland), A.J. Levan (Univ. Warwick) J.P.U. Fynbo, B. Milvang-Jensen 
(DARK/NBI), report on behalf of a larger collaboration.

We provide further analysis of the photometric data on the afterglow of 
GRB 090519 (Perri et al., GCN 9400) taken at the NOT and VLT (Thoene et 
al., GCN 9403; Levan et al., GCN 9409).

Calibration of the field based on archival VLT zeropoints yields a 
significantly fainter magnitude for the afterglow with respect to our 
previous GCN 9403, which was based on USNO stars. The new calibration is 
consistent with SDSS stars and with the value reported by Rossi et al. 
(GCN 9408). We find for the afterglow R = 22.8 on 2009 May 19.897 UT 
(0.33 hr after the GRB).

The decay of the afterglow is well described by a power law with index 
alpha = 0.44 +- 0.03 between 0.33 and 3.6 hr after the GRB.