[AAVSO-HEN] GRB 080120: GROND detection

[grb at aavso.org]

The following is a GCN Circular circulated via the AAVSO network.
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TITLE:   GCN CIRCULAR
NUMBER:  7197
SUBJECT: GRB 080120: GROND detection
DATE:    08/01/21 08:13:12 GMT
FROM:    Jochen Greiner at MPI  <jcg at mpe.mpg.de>

T. Kruehler, J. Greiner, S. McBreen, S. Loew, A. Kuepcue-Yoldas, A. Yoldas 
(all MPE Garching) report for the GROND team:

We started observing GRB 080120 observed by INTEGRAL (Mereghetti et al. 2008,
GCN #7194) simultaneously in grizJHK with GROND, mounted at the 2.2m MPI/ESO 
telescope at La Silla (Chile), at 7:02 UT, about 13.5 hrs after the GRB. 
At this time, the GRB location was becoming visible at 20 degrees 
above horizon.

We find an optical/NIR source inside the 3.8 arcsec Swift/XRT error circle 
of the X-ray afterglow (Sbarufatti et al. 2008, GCN #7195). The object is
seen in all bands except K, implying a redshift smaller than 3.5.

The coordinates are (+-1 arcsec):
RA (2000.0) = 15h 01m 03.2s
Decl (2000.0) = -10d 52' 30"

We estimate rough magnitudes of g'=21.1, r'=20.5, i'=20.0, z'=19.8,
J=19.6, H=19.4, K>18.9, calibrated against USNO and 2MASS stars. 
Given the high airmass and humidity, these estimates may have large errors.

No statement about variability can be made at this point. Observations are 
continuing.