[AAVSO-HEN] GRB 080723B: GROND upper limits

[grb at aavso.org]

The following is a GCN Circular circulated via the AAVSO network.
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TITLE:   GCN CIRCULAR
NUMBER:  8079
SUBJECT: GRB 080723B: GROND upper limits
DATE:    08/08/08 20:19:08 GMT
FROM:    Jochen Greiner at MPI  <jcg at mpe.mpg.de>

T. Kruehler, J. Greiner, F. Schrey, G. Sala, C. Clemens (all MPE Garching) 
report on behalf of the GROND team:

We observed the field of the INTEGRAL GRB 080723B (Gotz et al. 2008, 
GCN #8002) on two epochs, 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). First observations started at 
2008-07-24 23:46 UT, 36.4 h after the burst, with total exposures of 
50 min in g'r'i'z' and 40 min in JHK. A second set of images was obtained 
starting at 2008-07-31 23:39 UT with effective exposures of 100 min 
(g'r'i'z') and 80 min (JHK).

We do not detect a fading source in neither the XRT (Page 2008, GCN #8008) 
nor XMM (Sala et al. 2008, GCN #8078) error circle down to limiting 
magnitudes of:

g' > 23.4
r' > 23.6
i' > 22.7 
z' > 22.7
J > 20.6
H > 19.5
K > 18.5

calibrated against USNO-B1 and 2MASS field stars. At longer wavelength,
these limits are compromised by the high density of foreground stars.

The reported upper limits are not corrected for the expected Galactic 
foreground extinction corresponding to a reddening of E_(B-V) = 1.3 
(Schlegel et al. 1998).