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Telescopes - Coggle Diagram
Telescopes
Quantify the Performance
image scale: S = F·θ
plate scale: 1/F = θ/S
point source
human eye limit magnitude is 6.5
limiting magnitude: m = 5
lgD + 2.5
lgt + C
surface brightness
focal ratio: R = F/D or f/R
fast -- small f/R
slow -- large f/R
field of view
FOV = 2
arctan(w/(2
f)), w is the sensor width
Point Spread Function(PSF)
diffraction
Airy Disk: θmin = 1.22*λ/d
FWHM ~ 2.35*𝜎
PSF is often spread out in within ~4𝜎 in diameter
1.7 × seeing (i.e. within ~2 × seeing)
corrector
adaptive
active optics
aberrations
spherical aberration
spherically shaped mirror has on-axis aberration
parabolic shape mirror has no spherical aberration
coma
astigmatism
distortion
Field curvature
Vignetting
basics
refracton and reflection
focus
Nasmyth focus
Cassegrain focus
Coudé focus
image scale: S = F·θ
telescope types
prime focus
Newtoian
Cassegrain
Gregorian
Schmidt-Cassegrain
Schmidt Camera
Maksutov
Refractor
telescope mounts
equatorial/polar
polar axis
declination axis
alt-az
height axis
azimuth axis