[vsnet-grb-info 7321] GRB 090205: GROND observations and photometric redshift estimate

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  8888
SUBJECT: GRB 090205: GROND observations and photometric redshift estimate
DATE:    09/02/06 07:26:53 GMT
FROM:    Thomas Kruehler at MPE/MPI  <kruehler at mpe.mpg.de>

T. Kruehler and J.Greiner (both MPE Garching) report on behalf of the
GROND team:

We observed the field of GRB 090205 (Swift trigger 342121, M. Perri et
al.,GCN #8884) simultaneously in g'r'i'z'JHK with GROND mounted at the
2.2m ESO/MPI telescope at La Silla Observatory (Chile).

Observations started on 03 Feb. 2009 at 05:25 UT, 6.33 h after the burst.

The object reported by D'Avanzo et al. (GCN #8887) is very well detected
in the i' band and redder, marginally in r' and not in g'. A preliminary
i' band magnitude is 20.7 +- 0.2 roughly 7 hours after the burst.
Interpreting the large r'-i' color and the g' band non detection as
Lyman-alpha absorption in the GRB host, we derive a photometric redshift
of 4.7 +- 0.3. This redshift estimate has been obtained using hyperZ
(Bolzonella et al. 2000). We caution that this is based on a preliminary
calibration.

No statement about variability can be made at this point.