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GCN Circular 6372

GRB070429B: VLT observations
2007-05-01T21:57:49Z (17 years ago)
Angelo Antonelli at Obs. Astro. di Roma <>
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 

We observed the refined XRT error circle of the short burst GRB 070429B 
(Beardmore et al, GCN 6360) 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); 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.

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