[AAVSO-HEN] GRB090518: GROND upper limits

[grb at aavso.org]

The following is a GCN Circular circulated via the AAVSO network.
For an archive and more information on circulars visit:
http://lheawww.gsfc.nasa.gov/docs/gamcosray/legr/bacodine/gcn3_archive.html

TITLE:   GCN CIRCULAR
NUMBER:  9395
SUBJECT: GRB090518: GROND upper limits
DATE:    09/05/19 02:37:52 GMT
FROM:    Andrea Rossi at TLS Tautenburg  <rossi at tls-tautenburg.de>

A. Rossi (Tautenburg), P. Afonso and J. Greiner( both MPE Garching) report
on behalf of the GROND team:

GROND (Greiner et al. 2008, PASP 120, 405), mounted at the 2.2m ESO/MPI
telescope at La Silla Observatory (Chile), observed the field of GRB 090518
(P. Evans et al. 2009, GCN #9386) simultaneously in the g'r'i'z'JHK
bands. Observations started on May 18, at 23:01 UTC, 21.1 h after the burst.
In stacked images of 49 min total integration time in griz and 40 min in
JHK, we do not detect any new object inside the enhanced XRT error circle
(P. Evans et al., GCN #9387), down to the following limiting magnitudes
(all in the AB system):

g' > 24.5
r' > 24.9
i' > 24.2
z' > 23.8
J  > 22.4
H  > 22.1
K  > 21.2

The upper limits have been obtained using GROND zero points and 2MASS
field stars as reference. No correction has been made for the expected
extinction corresponding to E(B-V) of 0.04 mag.