[daip] RE: New Zealand and UVCON

[Stuart Weston]

Dear Leonid,

Awesome thank you very much for your reply.

Yes my XYZ are earth centered coords.

Thank you for your patience, you are right to assume that I am new and
have a basic understanding of what I am dealing with here. Its 25 yrs
since I graduated in Physics from Manchester, UK and have only just gone
back for an M.Phil this year.

I will go through your suggestions today. Once again thank you very very
much for the assitance it is very much appreciated.

Stuart

> Dear Stuart,
>
> First of all I'like to recomend you starting hadlinng UVCON with the
> model given at SMODEl:
>
> Say
>
> SMODEL = 10, 0
> It means that UVCON will create the UV data for the point source with
> flux=10 located at the center.
> IN2name can be left blank at this case.
>
> Such an aproach will aloow you to feel the input file and simulated
> uvdata (outname, ...).
> Having created succesfully output uvdata you can run UVPRT and see all
> visibilities equaled 10 because
> the model source is the point source with the flux 10.
>
> Do you understand parameters INVERS, BCOMP, NCOMP, CMETHOD, CMODEL?
> They describe the model details when it is determined as an IMAGE or CC
> component file
>
> Now step by step about your problems:
>
> 1.If  you type 'aips > getn 4' to revoke in2name,.. for the model you
> are doing wrong.
> You have to type 'get2n 4'
> Anyway you should see the expected in2name, in2class, in2seq, in2disk at
> the list of iUVCON inputs.
> You can reach it typing directely: in2name='...", in2class=...,
> in2seq=.., in2disk=...
> This is a technical problem not related with UVCON.
>
> 2. About your input file.
> I do not like the stars at the second lines (positions at the equatorial
> coordinate system) of the UVCON print out. Check your X, Y, Z
>  What are they (X,Y,Z)?  You use the first column at you input file as
> '1' . That means axis Z is directed to local zenith.
> Your XYZ are supposed (I think so)  to have origin at the Earth center.
> Do you understand what is the "local"zenith at this case?
> If  XYZ are positions at the equatorial coordinate (I guess so) system
> then the first column shoud be '0'!!
> (read the explain file to UVCON.
> The first line (for each antenna) and the second line at the UVCON print
> out should be identical  at this case.
> You can use the standard VLBA file (just for practicing). You should
> type INFILE='AIPSTARS:VLBA_UVCON'
>
> 3. You used default for APARM, BPARM...
>     It is not a good idea. For example BPARM(1)=0   => the noise is
> added to the data with factor 1
>   (read help!) I do not thoink you you want to start simulation with
> noise. Pay attention on APARM(1-7)
>
> Any other questions about UVCON send to me and to daip at nrao.edu
>
> Leonid Kogan
>
>


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Email         : stuartweston at astronomy.org.nz