User:Ana/telescopes
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e.g. Milanković telescope has a focal length of 11.2 m, aperture of 1.4 m and F#=8: plate_scale = 206265 / 11200 = 18.42 ["/mm]. | e.g. Milanković telescope has a focal length of 11.2 m, aperture of 1.4 m and F#=8: plate_scale = 206265 / 11200 = 18.42 ["/mm]. | ||
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| + | Pixel scale is the size of the pixel 'in the sky': | ||
pixel_scale = plate_scale ["/mm] * pixel_size [mm/pix] | pixel_scale = plate_scale ["/mm] * pixel_size [mm/pix] | ||
Revision as of 12:15, 1 July 2019
Basic geometry
Plate scale of a telescope is the size of the square degree in the sky (in arcseconds) "seen" in the focal plane of the telescope measured in millimeters and is inverse proportional to the focal length of the telescope, that is equal to the product of the F-number (F#) and the diameter of the telescope's primary mirror D[mm]:
plate_scale = 1 square_degree[arcsec] / f[mm] = 1/(F#*D[mm]) = 206265 ["] / f [m] * 10^(-3)
e.g. Milanković telescope has a focal length of 11.2 m, aperture of 1.4 m and F#=8: plate_scale = 206265 / 11200 = 18.42 ["/mm].
Pixel scale is the size of the pixel 'in the sky':
pixel_scale = plate_scale ["/mm] * pixel_size [mm/pix]
e.g. CCD camera U42 used with the telescope has 2048 x 2048 pixels of 13.5 $\mu$m each. So, 1 pixel = 13.5 * 10^(-3) mm, i.e. 1 mm = 1/13.5 * 10^3 1/pix: pixel_scale = 18.42 ["] * 13.5 * 10^(-3) = 0.249 "/pix.
FOV = (#pixels x pixel_scale) x (#pixels x pixel_scale) = (2048 x 0".249) x (2048 x 0".249) = 509".3 x 509".3 = 8'.5 x 8'.5
