[evla-sw-discuss] Getting pulsar parameters to WIDAR

[Barry Clark]

I'm afraid I don't understand things very well, but somebody should
be talking about this, so here goes.

I believe the standard for predicting pulsar timing is the program 
tempo, maintained at CSIRO and/or Princeton.  (There is some attraction
to pulling out the guts and integrating them separately as we have 
done for CALC, but with obvious disadvantages as well.)

I believe the thing an observer should supply is a tempo parameters 
set, which would need to be passed through the OPT (without it having
to look at it, really).

I think further processing needs to be done during or near observation.  
To the supplied parameters, we should add TAI-UTC, UT1-UTC and possibly 
the other earth-orientation parameters.  True, we could force observers 
to make corrections for these after observation, but to do so seems cruel.

This processing could be done at OPT_model => script conversion time
or during observation.  Tempo's output is a polynomial.  Walter, can
we make a polynomial that will last for an entire scheduling block of
a few hours?  It looks close for some of the nastier doubles.  If not,
it is perhaps better to run tempo at observe time, one observation at
a time - seems less complicated than having the script writer supply
several sets of polynomials.

The polynomials output from tempo are in terms of phase and derivatives, 
not period and derivatives, as shown in the draft VCI.

For transferring the model across the VCI, we can either send along 
lots of coefficients (up to a dozen, perhaps) at (sub)scan setup time,
or have the AntennaPhysicals send along three coefficients to the 
station boards, packaged with the delay models, every 10 seconds or so,
which looks adequate.