Note on Calibrators for the LBA
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Basically there are two kinds of (total flux) calibrators in VLBI:
 
1) FRINGE FINDERS: which are strong sources near the source of interest to
estimate delay and rate errors due to correlator model errors other than
source position. Particularly handy to correct large clock errors.
 
LBA staff will help you with this when preparing the observing schedule with 
you. Meanwhile the ICRF (International Celestial Reference Frame) sources at 
   http://rorf.usno.navy.mil/rrfid.shtml
and 
   http://www.vlba.nrao.edu/astro/calib/
are, potentially, a good list of such calibrators.

NOTE 1: Souces categorised as "(D)efining are likely to be best but
(C)andidate will usually be fine.
 
NOTE 2: Structure Index (in column 3) is described as below:
"Fey and Charlot 1997 define a source "structure index" based on the
median of the calculated structure corrections. They suggest that this
index can be used as an estimate of the astrometric quality of the sources 
as follows: Sources with an X-band structure index of 1 may be considered
very good astrometric sources. Sources with an X-band index of 2 may be
considered good sources, while sources with an X-band index of 3 should
be considered marginal (and should only be used with caution). Finally,
sources with an X-band index of 4 should not be used at all for
astrometric work. In addition, sources should have an S-band structure
index of either 1 or 2, with a preferred value of 1, regardless of the
value of their X-band structure index."

2) PHASE REFERENCING: where observations of a calbrator source are
interleaved with those of the target. Then fringe fit solutions for the
calibrator source can be used to calibrate delay, rate and phase residuals
of the target.
 
For this to work the structure of the calibrator source must be known
before fringe fitting (so that the effects of structure can be removed).
Currently we do not have this information so if you wish to do phase
referencing you will first have to do an experiment to go looking for
suitable calibrators in the part of the sky your target is located.

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Updated 06-feb-2009