[AAVSO-HEN] GRB 080906: GROND observations of the optical/NIR afterglow

[grb at aavso.org]

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TITLE:   GCN CIRCULAR
NUMBER:  8194
SUBJECT: GRB 080906: GROND observations of the optical/NIR afterglow
DATE:    08/09/07 09:44:25 GMT
FROM:    Paulo M. J. Afonso at MPE  <pafonso at mpe.mpg.de>

GRB 080906: GROND observations of the optical/NIR afterglow 

P.Afonso, T. Kruehler, J. Greiner, C.Clemens, A. Yoldas (all MPE Garching)
and A. Kuepcue Yoldas (ESO) report on behalf of the GROND team: 

We observed the field of GRB 080906 (Swift trigger 323984; L. Vetere et
al., GCN #8186), simultaneously in g'r'i'z'JHK with GROND (Greiner et al.
2008, PASP 120, 405) mounted at the 2.2m ESO/MPI telescope at La Silla 
Observatory (Chile). 

Observations started at 00:12 UT on September 7th, 2008, 10.7 hrs after
the GRB trigger.We detect the optical afterglow reported by  L. Vetere et
al. (GCN #8186) at a position consistent with the UVOT detection in all
bands, implying a redshift smaller than 3.5. 

Preliminary photometry yields the following magnitudes calibrated against
USNO-B1 and 2MASS field stars in stacked images: 

Band  Exp(min)   Mag 

g'    24         22.2 +- 0.1
r'    24         21.4 +- 0.1
i'    24         21.2 +- 0.1
z'    24         21.2 +- 0.1
J     20         20.2 +- 0.1
H     20         19.2 +- 0.1
K     20         18.5 +- 0.1 

not corrected for the expected Galactic foreground reddening of E(B-V) =
0.30 mag (Schlegel et al., 1998).