GCN Circular 2476

GRB 031203: Deep NIR NTT & VLT observations


G. Tagliaferri, S. Covino, D. Fugazza, S. Campana, A. Simoncelli (INAF-OAB)
G. Chincarini (UNIMIB & INAF-OAB), L. Stella (INAF-OAR)


On December 5th, at 06:12 UT, we started observing in JHKs filters with 
ISAAC
at the VLT-UT1 telescope the XMM source S1 (Santos-Lleo & Calderon 
GCN2464
Not found
 
 
).
In the XMM error box of 6" around S1 we detect the source already seen 
in the
previous night with the NTT (Zerbi et al. GCN2471
Not found
 
 
, see also Hsia et al. 
GCN2470
Not found
 
 
).

With ISAAC we obtained the following magnitudes (based on 2MASS stars):
J=18.40+/-0.15, H=17.80+/-0.15 and Ks=16.70+/-0.15. A comparison between the
NTT values on December 4 and the VLT one of the following night shows that
this object faded by few tens of magnitude. Given that this object was 
already
detected in archive images (Bloom et al. GCN2472
Not found
 
 
), it is probably a 
variable star.

In the XMM error box with ISAAC we detect also another source with 
J=21.05+/-0.25
(not visible in H and Ks). This object was already present in the SofI J 
image and
it does not seem to have varied. We did not see any variable source in 
an area of
20 arcsecond radius around the XMM S1 position. Therefore, we have no 
indication of
a transient associated with GRB 031203. However, note that the VLT 
images do not cover
the full INTEGRAL error box, in particular the area around the XMM S2 
source is not in the FoV.


For the NTT SofI Ks finding charts, see 
http://www.merate.mi.astro.it/~taglia/GRB031203.jpg

We thank the ESO La Silla and Paranal staff for their prompt reaction 
and support.
This message can be cited.