TITLE:   GCN CIRCULAR
NUMBER:  10031
SUBJECT: GRB 091003: Gemini-N redshift of possible host galaxy
DATE:    09/10/18 19:20:08 GMT
FROM:    Antonino Cucchiara at PSU  <cucchiara@astro.psu.edu>

A. Cucchiara, D. B. Fox (PSU), S. B. Cenko (U. Berkeley), N. Tanvir (U. 
Leicester),
E. Berger (Harvard U.) report on behalf of a larger collaboration:

"On October 17.20 UT we observed  the possible host galaxy of the Fermi/LAT
GRB 091003 (McEnery at al, GCN 9985 and Perley et al. GCN 9997) with
Gemini GMOS-N.

We took a sequence of 2 spectra of 1800s each covering the 6000-10000A
wavelength range. The spectra clearly show emission lines which we 
interpreted
as [OII]3727, Hbeta and we resolved the [OIII]4959,5007 doublet.
All these identifications are consistent with redshift z = 0.8969 for 
this galaxy.

The galaxy is detected in our 300s R-band acquisition image.
The estimated magnitude, calibrated using 3 SDSS stars is:

R = 22.65 +- 0.05 mag

This value is brighter than the cataloged magnitude, which may indicate a
contribution of the afterglow. After subtracting the contribution
of the galaxy we derive an estimate of the OT flux, R = 23.65 +- 0.05 mag.

We thank the Gemini staff for performing these observations."