about Jy and Jy/beam

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hzhangshao2011
Posts: 9
Joined: Sun Dec 18, 2011 2:50 am

about Jy and Jy/beam

Post by hzhangshao2011 »

Hi, all,
Is there anyone could tell me how to convert the flux unit 'Jy/beam' to 'Jy' ?
Thanks!
Hui
Arpad
Posts: 12
Joined: Thu Feb 24, 2011 1:50 am
Location: Germany

Re: about Jy and Jy/beam

Post by Arpad »

Hi Hui,

Thats a good question... I always trusted the output of kvis and miriad...
As Far as I know (and I might be wrong :)) you need your beam shape which is circular in an optimal case. If you then know your cell size (or pixel size), you can calculate how many pixels fit into your beam. So you would , so to say, convert from Jy/beam to Jy/pixel. After that you just take the number of pixels in the area of which you want to get the total flux, then your flux should be Jy/pixel * N pixels. Although I think someone told me once that there is a an ln(2) factor somewhere in the calculation... So probably its better if we wait for a better answer :)
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