[alma-config] Re: pointing error in UVCON

[morita]

Dear Leonia,

I do not know my procedure is correct or not, but I calculate
DR and FI by following sequence:

1. Reference image = CLEAN beam ** (Model image x Primary Beam)
2. Pick up ON-SOURCE pixels or OFF-SOURCE pixels using the Reference
   image and an appropriate clipping level.
3. Residual image = CLEAN image - Reference image
3. DR = 
  (Max of the reference) / (rms of Residual on the OFF-SOURCE pixels)
4. FI = 1 / median(abs(Residual) / Reference on ON-SOURCE pixels)

I am using IDL procedures for these calculations.

> I used the M51 image as my model. This image was given to me by John Conway.
> 
> The result of my simulation with pointing error is given at the table:
> 
> __________________________________________________
> Pointing error |     0      |  5+2=7" |  5+10=15"|
>                |            |         |          |
> MYFIDELITY     |   342      |   236   |   103    |
> __________________________________________________
> 
> The pointing error's first item is the global error simmulating the
> possible error of the source position. The pointing error's second item
> is the random component of the error with the given rms.

Do you mean the global error is constant error during observation and
among antennas?

> 
> I used the wavelength=1.8mm that gives (for D=12m) FWHM_PB=30".
> The model size is ~4".

This model is quite compact!  
> 
> I may suppose that your right definition of FI will give a lower value
> for my model, because the M51 is much more complicate than your
> gaussian sum.

How about dynamic range?  Maybe, you can easily calculate rms error
on OFF-SOURCE pixels.  

> If you want and can use the AIPS you can play with UVCON.
> Anyway I'd like to play with it using your model.

If so, I put these FITS file on my web site.

Regards,
Koh-Ichiro