[daip] questions

[Eric Greisen]

On 06/23/2019 06:39 PM, Chen, Diana wrote:
> Hi Eric,
> 
> 
> I've been reading up more on chapters in the Thompson book, and I have 
> some more questions.
> 
> 
>   Each telescope in the array measures a voltage signal collected from a 
> small field, and then the signal is multiplied with another telescope's 
> time delayed signal to pick out the radiation from a particular point in 
> the sky. However, whenever I read up on visibilities, there is always a 
> 2D fourier transform. How do we go from a voltage signal at a point 
> source to a 2 dimensional problem?
> 
> 
> Thanks,
> 
> 
> Diana
> 
The sky contains many point sources (if the actual source is extended)
and so the signals add with various phases depending on where in the sky 
and the projected baseline.  One integrates over the possible sky 
positions.  Even if it is just a point source, we may not have the 
coordinate exactly correct - so it will appear at a piel other than the 
center.

Eric