[evlatests] Collimation errors, and a problem with the OPT ...

[David Harland]

Rick,

It seems to me like we could make such a change. Where i now create a
single refPtg variable that holds only the most recent results, i could
create one for every ptg scan. In the OPT user interface we'd then
need to allow users to say which one they want to reuse.

I'd like to hear Lorant &/or Bryan weigh in before making this an
official to-do item.

David


Rick Perley wrote:
>     ... 
>
>     3) An OPT issue:  The OPT has a very useful capability when 
> determining a referenced pointing solution:  One can either determine it 
> 'blind' (i.e., without applying a previous solution), or one can 
> determine the solution after applying the (not 'a') previous solution, 
> and hence determine a 'differential' solution, which is then properly 
> added to the earlier offsets.  This, for example, permits a Q-band 
> referenced pointing differential offset from another band (such as 
> X-band).  This is a very useful capability when one is trying to get the 
> very best pointing, and is worried about residual collimation offsets. 
>        However, the problem is that this useful feature can *only* apply 
> the pre-existing solution, and does not allow one to  use a single 
> reference pointing band, such as X-band, as reference for all others.   
> So, for example, in my case, the X-band solution is used for Ku-band, 
> the Ku-band solution was used for K band, K-band solution for Ka-band, 
> and Ka-band for Q band.  Not a problem is there is not a  large 
> collimation offset between those pairs of bands -- but a *big* problem 
> if there is.  (And there was!). 
>     Is it possible to have the OPT remember a particular solution (not 
> just the existing one), and apply that one to subsequent observations?  
> That is, develop a true 'secondary referenced pointing' capability, like 
> we used to have?