3+4+2 = 9 Marks A space telescope has a very stable point spread function (PSF). Therefore the central position of the P

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3 4 2 9 Marks A Space Telescope Has A Very Stable Point Spread Function Psf Therefore The Central Position Of The P 1 (90.57 KiB) Viewed 250 times

3+4+2 = 9 Marks A space telescope has a very stable point spread function (PSF). Therefore the central position of the PSF for a star can be measured accurately, enabling the determination of its centre to high precision (which in turn is crucial for parallax and/or proper motion measurements). (a) How does the angular resolution of the telescope (i.e. the PSF full-width half- maximum) scale with the aperture of the telescope and wavelength? (b) Considering that photon collection is a Poisson process, write an order of magnitude expression for the expected error on the measurement of the centre of the PSF, as a function of the number of photons collected. (c) Considering a given stellar target, a fixed exposure time and a fixed wavelength, determine how the precision on a parallax measurement scales with aperture of the space telescope assuming the PSF centroid determination is the limiting factor of the measurement.