Size estimation of CCD and ideal width of pointspread function

[moonspell]

Hi I have a problem to solve and I'm stack, so I would really appreciate your help if anyone can tell me how to answer the following question:

"Consider a sky imaging system that has a 100m wide FoV measured at 1km from the camera; and that images a passenger airliner at a height of 2km as 10 pixels long. Estimate the size, in pixels, of the silicon CCD; and the ideal width, in degrees of the pointspread function due to the optical part of the system"

Thanks!

 

[cepheid]

I would say that the first step would be to figure out the field of view of the camera. If you sweep out an arc-length of 100 m at a radius of 1 km, what angle have you swept out?

If you use a reasonable estimate for the length of a passenger jet, then you can figure out what angle it subtends when at an altitude of 2 km. So you know the ratio of its angular size to the angular size of the FOV, which means you know the ratio of the width of 10 pixels to the width of the whole CCD.

Answering the above question tells you the angular size of one pixel (on the sky). You know you want your PSF to be reasonably well-sampled -- larger than a pixel size, but not too large. That gives you a good sense of what you'd want the angular size of your PSF to be.