[AAVSO-HEN] GRB 080520, GROND observations

[grb at aavso.org]

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TITLE:   GCN CIRCULAR
NUMBER:  7756
SUBJECT: GRB 080520, GROND observations
DATE:    08/05/21 06:24:35 GMT
FROM:    Andrea Rossi at TLS Tautenburg  <rossi at tls-tautenburg.de>

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A.Rossi, R. Filgas (Tautenburg), T. Kruehler, J. Greiner (MPE Garching),
S. Klose (Tautenburg), A. Kupcu-Yoldas, A. Yoldas, and
G. Szokoly (Eoetvoes Univ. Budapest and MPE)
report on behalf of the GROND team:

We observed the field of GRB 080520 observed by SWIFT (D. Grupe et al. GCN 7753)  simultaneously in grizJHK with GROND (Greiner et al. 2008, PASP 120, 405) mounted at the 2.2m MPI/ESO telescope at La Silla (Chile).
Observations started at 01:19 UT, about 2.9 hrs after the GRB.
At this time, the GRB location was becoming visible at 20 degrees
above horizon.
Observations were performed at relatively high airmass and under challenging sky conditions with cirrus and a bright moon.

The afterglow candidate detected by UVOT, reported by D.Grupe et al. 
(GCN 7753) is detected in g'r'i'z' J , implying a redshift smaller than 3.5.

We estimate a rough magnitude of i'=21.38 +/-0.4 at 3.25 hrs after the GRB, 
calibrated against USNO-B field stars. We stop observations due to bad sky
conditions.

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