[AAVSO-HEN] GRB 090417B: Gemini imaging

[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:  9158
SUBJECT: GRB 090417B: Gemini imaging
DATE:    09/04/18 18:54:50 GMT
FROM:    Edo Berger at Harvard  <eberger at cfa.harvard.edu>

E. Berger (Harvard), D.B. Fox (PSU), and N. Tanvir (Leicester) report:

"In addition to the spectroscopic observations described in GCN 9156, we
also imaged the field of GRB 090417B with GMOS in the griz filters
starting on 2008 April 18.38 (17.7 hours after the burst).  A total of 360
sec were obtained in gri, and a total of 540 sec was obtained in z.  We
find the following magnitudes for the SDSS galaxy coincident with the XRT
afterglow position:

g = 22.47+/-0.16 mag	(SDSS: 23.0+/-0.5 mag)
r = 21.62+/-0.10 mag	(SDSS: 21.62+/-0.16 mag)
i = 21.31+/-0.12 mag	(SDSS: 21.41+/-0.09 mag)
z = 21.49+/-0.30 mag	(SDSS: 20.78+/-0.25 mag)

Thus, we find no evidence for brightening compared to the SDSS archival
magnitudes."