TITLE:   GCN CIRCULAR
NUMBER:  22302
SUBJECT: VLBA detection of GRB 171205A
DATE:    18/01/05 18:39:30 GMT
FROM:    Miguel Perez-Torres at IAA-CSIC  <torres@iaa.es>

Miguel Perez-Torres (IAA-CSIC), S. Bradley Cenko (NASA), Assaf Horesh 
(HUJI),
and Antxon Alberdi (IAA-CSIC) report:

We observed GRB 171205A (D'Elia et al., GCN 22177) with the Very Long
Baseline Array (VLBA) on 2017 Dec 15.53 UT and 2017 Dec 16.56 at several
frequencies. We centered our observations at the VLA position of GRB 
171205A
(Laskar et al., GCN 22216), and imaged a region of (0.5x0.5) sq. arcsec 
around it.
At a frequency of 4.4 GHz, we detect GRB 171205A with a preliminary peak 
flux
density of ~2.3 mJy/beam at the following position:

RA  =  11:09:39.5179609
Dec = -12:35:18.459250

The (preliminary) uncertainty on the position of the peak flux density 
is of
~130 and ~50 microarcsec in RA and Dec, respectively.

More VLBI follow-up observations of GRB171205A are on the way.
We thank the NRAO staff for the time allocation and their help with the 
observations.