Question: A survey of a region of the sky was carried out at ESO (European Southern Observatory) with the following observational conditions: - Telescope aperture: 2.2 m - Exposure time: 35s -...

Extracted text: Question: A survey of a region of the sky was carried out at ESO (European Southern Observatory) with the following observational conditions: - Telescope aperture: 2.2 m - Exposure time: 35s - Signal/noise ratio: 65 - Filter width: 138 nm Sky conditions: very good. All stars with magnitude 19 were observed in each CCD image, that is, the survey is complete up to magnitude 19 in the color and wavelength range used. a) Assuming the same general conditions, calculate the ratio that provides the exposure time required for a D-aperture telescope, to be complete up to magnitude m and filter width AA. b) Calculate the required exposure time for m=20, AA=20 nm, and D=1 m, 2 m, 3 m, 4 m and 8 m.