Monday, October 20, 2008

Multi-scale clean vs. regular clean

Those of you clean afficiandos should check out this recent astro-ph article:
Multi-Scale CLEAN: A comparison of its performance against classical CLEAN in galaxies using THINGS



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SUBIM question

A question from reader Jenny:

I'm trying to combine two optical images using AIPS (don't ask why!) but the FITS images I have are not centred on the sources I want to combine. I want to use SUBIM to create images centred on my targets but is there a way to get the task to create the image using the ra and dec of the target rather than TRC and BLC?


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Mystery Error: TASK HAS NOT BEGUN IN 15.1 SECONDS

A question from Tony:

Has anyone start getting the following error message:

AIPS 1: TASK HAS NOT BEGUN IN 15.1 SECONDS
AIPS 1: Begin check for any 'standard' scratch files
AIPS 1: Scratch files -- destroyed: 0 still active: 0
AIPS 1: Resumes

A few people across the department have receive the same error message, and I think it is a problem related to 31DEC08.

But why 15.1 seconds?!

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Tuesday, October 14, 2008

Imaging GMRT Data

A plea for advice from an anonymous reader:

Off topic, & quite possibly a stupid question from an AIPS newbie, but I'd really appreciate any help. I'm currently processing some GMRT data (30mins, 610MHz, 38 facets, each imsize 512, cellsize 1.5), & IMAGR seems to take a very long time to run, ~2hrs for 1000 iterations. I'm wondering if this is normal, or if something has gone wrong during the SPLAT process, where I split off the source from the multi source dataset, and averaged every 7 channels between channels 1 & 105.

IMAGR, with NCHAV=15,when running, appears to process channels 1-15, then 2-16,3-17 etc, is this normal for data that has been averaged as above?
Thanks.


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