[AAVSO-HEN] GRB 091117: Magellan optical 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:  10174
SUBJECT: GRB 091117:  Magellan optical observations
DATE:    09/11/19 06:06:15 GMT
FROM:    Edo Berger at Harvard  <eberger at cfa.harvard.edu>

E. Berger (Harvard) and J. Mulchaey (OCIW) report:

"We obtained optical r-band observations of the BAT error circle of GRB 
091117 (GCN #10171) with IMACS on the Magellan/Baade 6.5-m telescope 
starting on 2009 Nov 19.06 UT.  A comparison to DSS images reveals no 
new sources brighter than the DSS limit of about 21 mag.

The galaxy coincident with the XRT source within the BAT error circle 
(GCN #10173) has a face-on spiral morphology.  We find a single apparent 
point source coincident with one of the spiral arms.  This object may be 
the optical afterglow of GRB091117 or an unrelated bright HII region. 
Additional observations are planned to determine if the source exhibits 
fading behavior.

An image of the galaxy is available from:
	http://www.cfa.harvard.edu/~eberger/GRB091117_Magellan.gif