Can Miriad handle other Telescopes? and linmos question

Is MIRIAD being a pain? Let us know your experience.

Moderator: Mark.Wieringa

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Arpad
Posts: 12
Joined: Thu Feb 24, 2011 1:50 am
Location: Germany

Can Miriad handle other Telescopes? and linmos question

Post by Arpad »

Hi again,

Can miriad *properly* handle Data from other telescopes? For Example, I did some tests with EVLA data. The imaging part seems to be correct, even for polarization, ie. the values of dirty images agree with both systems. But, if ones comes to primary beam correction... does miriad know the beam properties of the EVLA or other telescopes?

And talking about linmos... If you do not have a mosaic and use linmos on it, it essential just does PB correction. Can it also stack images? For example, I split up a 2 GHz dataset and imaged a couple of chunks separately (no mosaic). If I use linmos on those chunks, are they then stacked properly? If I would do it manually, I would need to smooth every image to the largest beam, which can deviate notably from beginning to the end of the entire band, and then stack them somehow. Is linmos also doing this?

Thanks,
Arpad
Mark.Wieringa
ATCA Expert
Posts: 297
Joined: Mon Feb 08, 2010 1:37 pm

Re: Can Miriad handle other Telescopes? and linmos question

Post by Mark.Wieringa »

Hi Arpad,

Yes Miriad can handle data from many telescopes, often some adjustments are needed, but for many telescopes these are already there.
There is also the alternate miriad distribution from http://bima.astro.umd.edu/miriad/ which tries to unify all the various local miriad versions in use at various observatories and lets you compile specific customized versions for each.

If you run pbplot without specifying the telescop parameter, you get a list of all the primary beam models miriad knows about. VLA and EVLA are included, but whether these represent the truth at all frequencies is something you might need to investigate. We're happy to update them if required.

Linmos was recently updated to use the correct frequency for the primary beam for each image in a stack - this will improve the accuracy of the flux correction away from the field centre. No correction is made for differences in the synthesized beam between input images, so you'll end up with a straight average of the beam shapes, which wouldn't be too far from what you get if you image the whole band in one go.

Cheers,

Mark
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