TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  5283
SUBJECT: GRB 050223: Magellan redshift
DATE:    06/07/03 21:31:23 GMT
FROM:    Edo Berger at Carnegie Obs  <eberger@ociw.edu>

E. Berger (Carnegie) and Min-Su Shin (Princeton) report:

"We obtained spectroscopic observations of the host galaxy of GRB 050223
(GCN 5268) with the LDSS-3 spectrograph on the Magellan/Clay telescope on
2006 June 28 UT.  We find a single emission line at an observed
(vacuum-corrected) wavelength of 5933.8A, corresponding to [OII]3727 at a
redshift z=0.5915.  At this redshift, the observed brightness of the host,
R=21.6 mag (GCN 5268), corresponds to an absolute magnitude, M_B=-20.2 mag
or ~0.5L*.  We further detect an emission line at the same wavelength from
a galaxy about 1.3 mag fainter located 10" to the east of the host galaxy,
indicating that it is a companion to the host with a separation of about
65 kpc and a luminosity of about 0.15L*.

At the redshift of the host and with a fluence of 9.7e-7 erg/cm^2 (Page et
al. 2005, MNRAS, 363, L76), the isotropic-equivalent gamma-ray energy of
GRB 050223 is only 8.7e50 erg."