[daip] Fwd: Re: Updating VLBA correlation parameters

[egreisen]

-------- Original Message --------
Subject: Re: [daip] Updating VLBA correlation parameters
Date: 2021-03-16 14:40
 From: egreisen <egreisen at nrao.edu>
To: Andy Biggs <abiggs at eso.org>

On 2021-03-16 13:48, Andy Biggs via Daip wrote:
> Hi,
> 
> I have a question about updating the correlation parameters for old
> (~1995) VLBA data. I've written before regarding strange distortions
> of gravitational lens images in 'wide-field' (~1"), high dynamic range
> (~500) VLBA data and I'm now seeing the same effect in another lens
> system.
> 
> Running VLBAEOPS updates the values of UT1-UTC and the coordinates of
> the pole used when correlating the data. This causes new delays, rates
> and phases to be written into a CL table. What about the u,v,w's?
> Should these not be updated as well using e.g. UVFIX? This allows the
> user to update UT1-UTC, although the help says very clearly that the
> default in the AN table should be used. Should I actually be using one
> of the updated numbers reported by VLBAEOPS?

You can enter a new IT1UTC with BPARM(1) in UVFIX.  So you can try it
if you like.  I have forwarded your email to several VLB experts not
on daip to solicit their opinion.

Cheers

Eric