[daip] aips

[Amy Mioduszewski]

Dear Wu,

What you need to do is multiply the gains by the sqrt of the number you 
want the amplitudes to be multiplied by.  So if multiplying the 
amplitudes by 1.6 gets you to the right level then you need to multiply 
the gains by ~1.265.  This will put the correction in the SN table and 
you will then have to apply that

O.K., to put a model through a uv coverage is fairly simple if you have 
a uv dataset that has the uv coverage you want, and I think you do.  You 
use UVSUB, inputs of interest are:
INNAME uv dataset with the uv coverage you want to use
IN2NAME image you want to use as a model, you can also manually define
    a model with SMODEL
CMODEL 'COMP' --recommended over image models
FACTOR -1 --add the model
OPCODE 'MODL' --REPLACE visibilities in uv dataset with model vis.
-> Then just image the resulting model uv dataset.

So you can flag out antennas or whatever to change your uv coverage and 
see how that effects a the image.

Cheers,

Amy

zzwu wrote:
> Dear professor Amy mioduszewski:
>        Thank you for your explaination,you are so warm-hearted,two questions,you said that In aips I could do that with SNCOR(OPCODE='MULA') and multiply by the SQRT of the correction,does the SQRT of the correction means the sqrt of the value of the amplitude calibration,like your example,you found some VLA can be up to 20%,so I should multiply the value sqrt(1+20%).another question is you said I should do tests where I put model of the source structure through different uv-coverage and see how it changed the appearance of the source,what I do now is edit some antenna's data,and see the component's structure in difmap,
> I 'd very prefer if you can explain how to do it in AIPS though I do not do it in aips now,I think  the steps are the same  ,I can understand how it works ,then I will do it better,maybe I will try using aips image the data  later,then it will be helpful for me,thank you very much.
>           cheers 
>      wu