[AAVSO-HEN] GRB 090417B: Liverpool Telescope observations

[grb at aavso.org]

The following is a GCN Circular circulated via the AAVSO network.
For an archive and more information on circulars visit:
http://lheawww.gsfc.nasa.gov/docs/gamcosray/legr/bacodine/gcn3_archive.html

TITLE:   GCN CIRCULAR
NUMBER:  9144
SUBJECT: GRB 090417B: Liverpool Telescope observations
DATE:    09/04/18 09:13:41 GMT
FROM:    Cristiano Guidorzi at Ferrara U,Italy  <guidorzi at fe.infn.it>

C. Guidorzi (U. Ferrara), R. Smith, C.G. Mundell (Liverpool JMU),
A. Gomboc (U. Ljubljana), P. O'Brien, N. Tanvir (U. Leicester) on
behalf of a large collaboration report:

On 2009 April 18 at 03:10:50 UT we observed the Swift GRB 090417B
(Sbarufatti et al., GCN Circ. 9135) with the Liverpool Telescope
using the SDDS-R filter.

 From a 6x300 s frame, inside the revised XRT error circle we clearly
detect the SDSS galaxy already mentioned by Fynbo et al. (GCN Circ. 9140).
At a mid epoch of 12.10 hrs post burst we estimate its magnitude of
r'=21.9 +/- 0.3, calibrated with respect to nearby SDSS stars.
This value is consistent with that reported in the SDSS catalogue of
21.6 mag. We therefore conclude that this source is not the afterglow of
GRB 090417B, while it could possibly be its host galaxy, as already
suggested by Fynbo et al. (GCN Circ. 9140).