Beam PA in CABB

[saracmbr]

Hello everyone,

I've got a question regarding PA of the beam in CABB
I have the ATCA CABB data which has 2GHz bandwidth. I've split it to 500MHz chunks and
made the images. Each of the images has their own beam size which is understandable but
they have different position angle. Please note that observation time for
all these 4 images are the same. I don't understand why the position angle
of the beam is the function of frequency.

[ste616]

Hi Sara,

If you are talking about the synthesised beam (which I supect you are), and you are using the 16cm band (I assume, since you are trying to split the band up into 500 MHz chunks), the uv spacing for the same antenna pair at the same time will be very different at one end of the band than the other. Since your synthesised beam shape and size depends quite strongly on the uv distribution of your measurements, it is likely that such differences would result in a differently-shaped beam.

Let me know if this does not describe your situation.