[daip] UVFIX

[Eric Greisen]

Andy Biggs wrote:
> Hi there. I'd like to double check the procedure for correcting the u,v,w 
> error that is present in deep 21-cm images (referenced in AIPSLetter 
> December 31, 2007). If I understand it correctly, if my data were read 
> into AIPS by a post-31DEC07 July 5 version of FILLM then the default 
> settings of UVFIX (in particular UVFIXPRM(13)=0) should do the trick. Is 
> that right?
> 
> Furthermore, if my data were also observed at the wrong position, would 
> this have to be corrected with a second run of UVFIX, this time setting 
> the SHIFT parameter?

Your understanding appears right on.  Post July 5 FILLM has correct 
times so UVFIX should not do any time correction.  If there was an 
on-line error - and that never did get pinned down all that well - then 
UVFIX will correct it.  But it is better to do any significant position 
shift after that correction has been made - so in a 2nd run of UVFIX.

Eric Greisen