[daip] issues with RM task?

[Eric Greisen]

Sayali Avachat wrote:
> Hello, 
> 
> Thanks for your reply.
> These files should be OK, but please find attached files which are the 
> most latest ones. The folder include X, U, K and Q, PA files, all 
> convolved to same resolution using CONVL and OHGEO tasks, transposed 
> cube file and rotation measure map obtained from transposed file.

I ran RM on the older images and looked not only at the RM values 
returned but the uncertainties that came with them.  They are huge!
For example RM = 2500 plus or minus 1700 or 1300.  In other words, these 
data do not describe a proper rotation measure that can be solved by a 
simple task.  The answers that come out when the wider search algorithm 
is used are quite different from the answers with the simpler algorithm 
(but I suspect are wrong - one case -13000 to -10000 as the range in RM).

Perhaps a closer pair of frequencies is required to deal with the phase 
wrap uncertainties.  More likely however are issues with imaging - as 
described in the e-mail by Fraser Owen.

I will look at these latest images.

Eric Greisen