[Difx-users] Convention for DELAY, WET, DRY Polynomials {External} {External}

[Geoffrey B. Crew]

Unless something has changed, DiFX looks at the DELAY polynomial which 
includes the WET and DRY components which are provided for reference.

I had to reverse engineer this for the ALMA case where an 
atmosphere-included Calc was used for the ALMA array.   The tool 
calcifMixed.py (mpifxcorr/utils) was developed to do the subtraction.  
It worked very well in the ALMA case so I presume it was done 
correctly.  You may wish to review that script.

On 10/1/25 4:04 PM, Joe Skeens via Difx-users wrote:
> Hi all,
>
> I've been working on a routine that replaces the difxcalc 
> interferometric model with the near-field delay model given in 
> https://doi.org/10.1007/s00190-018-1217-0 using precise ephemerides 
> for satellite positions, and I have a question related to how the 
> polynomial models should be formulated in the .im file.
>
> Should the DELAY polynomial include the atmospheric delays in the DRY 
> and WET polynomials, or should the DELAY polynomial be purely 
> geometric, with the DRY and WET polynomials being added to the DELAY 
> polynomial during correlation?
>
> Thanks,
> Joe
>
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-- 
Geoff Crew
MIT Haystack Observatory
gbc at mit.edu