TITLE:   GCN CIRCULAR
NUMBER:  11522
SUBJECT: GRB 101225A: Keck redshift
DATE:    11/01/06 20:13:40 GMT
FROM:    Dong Xu at Weizmann Inst  <dong@astro.ku.dk>

D. Xu, A. Gal-Yam (WIS), J. P. U. Fynbo (DARK/NBI), report on behalf
of a large collaboration:

Spectroscopy of the host galaxy of GRB 101225A (Racusin et al., GCN
11493; Xu et al. GCN 11519) was carried out at the 10m Keck-I
telescope equipped with the Low Resolution Imaging Spectrometer (LRIS)
around 10 UT, 6th Jan. 2011, with a good seeing ~0.7". A 900s spectrum
was obtained and it consists of a red and a blue channels, covering
~3200-5500 A and ~5000-8200 A, respectively. The spectrum has a low
signal-to-noise ration and the trace is best detected in the red
channel. Three weak emission lines are found at a common redshift of
z=0.40, considered as Hbeta (4861 AA), and the O III (4960 AA, 5007
AA).

Isotropic energy: >~ 7.8+/-1.6 x10^50 erg, using the BAT fluence
(Palmer et al., GCN 11500)

The absence of evidence for an emerging SN at the above redshift
suggests that GRB 101225A is a SN-less or SN-weak long GRB event.

Further deep spectroscopic observations are encouraged.