GCN Circular 6372

L.A. Antonelli (INAF-OAR  & ASDC), L. Stella (INAF-OAR), G. Tagliaferri (INAF-
OABr), E. Jehin, L. Schmidtobreick (ESO),report on behalf of the MISTICI 
collaboration:

We observed the refined XRT error circle of the short burst GRB 070429B 
(Beardmore et al, GCN 6360
Not found
 
 
) with VLT-UT1 (Antu) and FORS2 in two different 
epochs. Images were taken in both the R and B bands starting on Apr. 29 at 09:
26:00 (about 5.5 hr after the burst) for a total exposure time of 900 sec in R 
band and 600 sec in B band. Another image of the field was taken in the R band 
only starting on Apr. 30 at 09:10:56 UT (about 29.5 hr after the burst) for a 
total exposure time of 1800 sec under better seeing conditions.

At both epochs we found two objects within the XRT error circle:

Object A is located well within the XRT error circle at:
     RA    = 21:52:03.7
     DEC = -38:49:42.9

Object B is located close to the border of the XRT error 
circle at:
     RA    = 21:52:03.4
     DEC = -38:49:43.1

Coordinates are J2000 and with an error of 0.2".

Object A was detected in R band at both epochs with good S/N. It appears to be 
extended and consistent with the revised position of the object observed by 
Cucchiara et al (GCN 6370
Not found
 
 
); its R magnitude is 23.2 +- 0.2,  calibrated by 
using the USNO B1 catalogue. Object A was only marginally detected in the B 
band. Object B was marginally detected in the first R band observation, with a 
better detection during the second night at a R mag of 24.6+-0.3. Also object 
B seems extended.

We find no evidence of a fading behaviour in either objects. Most likely one 
of them represents the host galaxy of GRB070429B.

We thank the ESO Paranal staff for their excellent support.

This message can be cited.


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