Note on Calibrators for the LBA
Basically there are two kinds of (total flux) calibrators in VLBI:
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 following resources provide useful information about
Note 1: Sources marked as "C" (calibrators) are safe for using as phase
calibrators and fringe finders (if they are bright enough). Sources marked
as "N" (non-calibrators) may be suitable as calibrators caution if additional
information is available. Sources marked as "U" (unreliable) should not been
used as calibrators without additional observations.
PHASE REFERENCING: where observations of a calibrator 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.
Note 2: Many sources are variable and exhibit changes in their structure.