[alma-config] Fw: CLEAN and difference results for the C resolution

[John Conway]

Hi Al, Steven et al,

 Next Tuesday at 1700UT  for a config telecon fine for me.

 I had a quick look at Stevens C-array results, I don't think
there is any evidence for problems due to sampling and with 
4 to 5 pixels per beam I guess one would not expect such 
problems. I would vote that he goes ahead and makes the B
and +23 dec simultions perhaps D as well. In parallel
he could try the other route of not pre-subsampling on one image
and see if there is any difference.

 Plotting the error maps for the two arrays with the same 
grayscale would make intercomparsion easier, as Steven says
its probably required to make  the images first then see what
the limits are and then replot - but I think that 
would be worth the effort. Perhaps also a summary
table of max, min errors and rms on each of the difference images
for each array might be useful, in navigating the results.

There seems in seveal images to be significant negatives
at the position of the peaks in the input models.
This  might suggest a wrong scaling of the CLEAN and comparison
image. On the other hand CLEAN is known not to do a great job on  
bright slightly resolve components (Dan Briggs thesis), and 
the sort of artifacts one gets, a minimum surrounded by 
positives looks like some of the results Dan got. 
Although these type of reconstruction errrors seem to dominate the
difference image in many cases (eg M51) they will  
be much less prominant in fractional error images. Forming
such fractional error images is the next step, implementing the
type of fidelity plots Stephane showed in his simulations
might be the best way to go/

    John 

 

 


On Wed, 15 Nov 2000, Al Wootten wrote:

> Folks,
> 
> I propose that we have a teleconference on e.g. Tues, 21 November at 1700UT
> to discuss the simulation progress so far and the revised schedule for
> making a configuration decision.  Many people are away this week at the
> Antenna PDR and Site Characterization meeting in Morocco; the latter
> part of next week is Thanksgiving in the U. S.
> 
> Can everyone make that time and date?  Agenda items?
> 
> Clear skies,
> Al
>  
>