1.23m Telescope on Calar Alto

Technical Details
Unit With Corrector Without Corrector
Aperture mm 1230
Focal Length mm 9807.6 9857.1
Central Obscuration mm ø 582
Effective Collecting Area 0.922
f/ratio 1/8
Back Focal Distance mm 852.1 849.9
Focal Range mm ± 200
FOV arcmin 90.2 90.0
mm 257.2 258.1
Aberration Free arcmin 15
mm 43.0
Scale "/mm 20.9
Hourangle Range h:min -15:06 to +14:50
Corrector Details
Lens 1 Lens 2
Diameter 290 mm 280 mm
Aperture 276 mm 258 mm
Shape Convex concave, spherical Biconcave, spherical
Center Thickness 25.1 mm 24.4 mm
Surface Antireflective coating on both sides, reflection minimum at 550 nm Antireflective coating on both sides, reflection minimum at 550 nm
Material Quartz Glass Quartz Glass

Image of the 1.23m telescope (354 kB)