Date: Tue, 12 Oct 2010 18:03:05 -0400 (EDT)
From: Jun-Hui Zhao 
To: melvyn wright 
Cc: Dan Marrone , smamiriad@cfa.harvard.edu,
     BobSault , Peter Teuben 
Subject: Re: miriad beta trouble



Hi Mel,
    I think that Chi2 was used in the three routines that Bob developed
for the SMA back to 2007. I confess that I never carefully looked into these
programs since SMA users made no attempts to test them upon my request. As
I mentioned to you while you were here for the CASPER, I plan to
look into these programs to see if they are useful for the calibration of
full polarization data.
    Jun-Hui
On Tue, 12 Oct 2010, melvyn wright wrote:

> Hi Jun-Hui,
>
> I'm not clear where you use  chi2.   Is it in additional uvvariable as well
> as chi ?
> A nicer way to handle this would be to use the existing uvvariabes :
> telescop or mount
> rather than introducing a new uvvariable.
> and code
> if ( mount.eq.' SMA') then   # or telescop .eq. ...
>    chi =                              # or other code as needed
> else
>    chi =
> endif
>
> M.
>
>
> On Tue, Oct 12, 2010 at 2:12 PM, Jun-Hui Zhao  wrote:
>
> >
> > Hi Mel,
> >    Chi2 was required by Bob Sault for polarization calibration.
> > Below is the email communication between Bob and I quite a while ago.
> >    Jun-Hui
> >
> >
> > >Date: Thu, 11 Jan 2007 13:05:32 -0500
> > >From: Bob Sault 
> > >To: 'Jun-Hui Zhao' 
> > >Subject: RE: FW: Time-multiplexed polarization observations
> >
> > >Jun-Hui,
> >
> > >If the SMA version of obspar has evec of pi/4, they I would trust that as
> > >the right answer. The ATNF version does not, but that is probably because
> > >the changes did not get back to the ATNF.
> >
> > >Could you make changes to smalod to reflect that evec is pi/4.
> >
> > >Thanks
> > >Bob
> >
> > >> -----Original Message-----
> > >> From: Jun-Hui Zhao [mailto:jzhao@cfa.harvard.edu]
> > >> Sent: Thursday, 11 January 2007 12:30 PM
> > >> To: Bob Sault
> > >> Subject: RE: FW: Time-multiplexed polarization observations
> > >>
> > >> Hi Bob:
> > >>     I have implemented a few things in handling the new variable chi2:
> > >> add it to the variable list in var.for and the VarChar data
> > >> array in varplt.for. I also realize that there is an inconsistence
> > >> between chi value and that produced in uvredo if we set evec=0.
> > >> Here is the definition that we used:
> > >>     chi   =  evec (evector) + chi (parallatic angle) - elev
> > >>     chi2  = -elev.
> > >> In uvredo, the evec is fetched from calling obspar
> > >> in which the evec =pi/4 is defined for SMA. Please let me
> > >> know which value is correct.
> > >>     Jun-Hui
> >
> >
 > On Tue, 12 Oct 2010, melvyn wright wrote:
> >
> > > chi and evector are official uvvariables.  what is chi2 ?
> > >
> > > M.
> > >
> > >
> > > On Tue, Oct 12, 2010 at 1:30 PM, Jun-Hui Zhao 
> > wrote:
> > >
> > > > I meant chi2 instead of Ch2.
> > > >       Jun-Hui