GCN Circular 6419

Cucchiara A. (PSU), Marshall F. E. (NASA/GSFC) and Guidorzi C.
(Univ. Bicocca&INAF-OAB) reports on behalf of the Swift/UVOT team:


The Swift/UVOT observed the field of GRB070518 starting
82 sec after the trigger (Guidorzi et al., GCN Circ. 6415
Not found
 
 
).
The afterglow was clearly detected in all the 7 filters.
This suggest a redshift lower than 0.7.

The estimated magnitude for the V and White filters are:

Filter        T_start(sec)     Exposure(sec)         Mag

White            82                 93            18.16 +/- 0.06
White           873                 94            19.14 +/- 0.09
White          5517                191            20.08 +/- 0.14
White          6951                191            21.33 +/- 0.20

V               187                391            19.31 +/- 0.13
V               978                391            20.08 +/- 0.24
V              5927                363            21.05 +/- 0.48


Assuming a single power-low, the decay index is ~1.17 in V band.
The extrapolated V mag at T+10h is 22.59.

The values quoted above are not corrected for the expected Galactic
extinction of E_{B-V} = 0.017 mag (Schlegel et al. 1998).