Transcription
Angular ResolutionASTR 288C: Lecture 6
Naked EyeAstronomical “Instruments”Typical size: 3-9 mm diameter pupilextremely portablecheapsubject to blinkingBest for bright, large-field observing
Naked EyeAstronomical “Instruments”Typical size: 3-9 mm diameter pupilextremely portablecheapsubject to blinkingBest for bright, large-field observingRefracting TelescopesLargest: Yerkes 102-cm (40-in) diameter lensTypical amateur: 60-mm diameter lenslittle maintenancereliablebest image qualityYerkesexpensive per aperture sizeheavy and bulky – size limitBest for solar system observing
Naked EyeAstronomical “Instruments”Typical size: 3-9 mm diameter pupilextremely portablecheapsubject to blinkingBest for bright, large-field observingRefracting TelescopesLargest: Yerkes 102-cm (40-in) diameter lensTypical amateur: 60-mm diameter lenslittle maintenancereliablebest image qualityexpensive per aperture sizeheavy and bulky – size limitBest for solar system observingYerkesReflecting TelescopesLargest single-mirror: Subaru & VLT 8.2-m diameter mirrorLargest segmented-mirror: GTC 10.4-m diameter “mirror”Subarucheaper per aperture sizeslight light lossgood image qualitymaintenance requiredlighter – larger sizes Best for (extra-)galactic observing
Diffraction and Angular ResolutionAiry PatternSingleMergingResolutionLimit
Diffraction and Angular ResolutionAiry PatternSingleMergingRayleigh’s CriterionTwo “point” (unresolved) sources areresolved from each other when separatedby at least the radius of the airy disk.Θ 1.22λDradResolutionLimit
Diffraction and Angular ResolutionAiry PatternSingleMergingResolutionLimitRayleigh’s CriterionTwo “point” (unresolved) sources areresolved from each other when separatedby at least the radius of the airy disk.Θ 1.22λDradCareful! λ and D are naturallymeasured in different unitsAlso note: 360 deg 2 π rad
Angular Resolution: Human EyePupil diameter:3-4 mm (day)5-9 mm (night)Optimal sensitivity: 0.55 µm (V band)Θ 1.22λDrad
Angular Resolution: Human EyePupil diameter:3-4 mm (day)5-9 mm (night)Optimal sensitivity: 0.55 µm (V band)Θ 1.22λDrad 1.220.55 µm3 mmrad180 deg1 mmπ rad103 µm
Angular Resolution: Human EyePupil diameter:3-4 mm (day)5-9 mm (night)Optimal sensitivity: 0.55 µm (V band)Θ 1.22λDrad 1.220.55 µm3 mm 0.0128 degrad180 deg1 mmπ rad103 µm3600”1 deg
Angular Resolution: Human EyePupil diameter:3-4 mm (day)5-9 mm (night)Optimal sensitivity: 0.55 µm (V band)Θ 1.22λDrad 1.220.55 µm3 mm 0.0128 deg 50” (day)rad180 deg1 mmπ rad103 µm3600”1 deg
Moon3 mm pupil30’
Moon9 mm pupil30’
Moontelescope30’
Largest single-mirror: Subaru & VLT 8.2-m diameter mirror Largest segmented-mirror: GTC 10.4-m diameter "mirror" Yerkes Subaru little maintenance expensive per aperture size reliable best image quality heavy and bulky - size limit extremely portable cheap subject to blinking Typical size: 3-9 mm diameter pupil
