Optical Properties

Basic Optical Parameters

Primary ("M1"):

Radius of curvature	21311.6 mm concave
Conic constant	-1.09763
Mirror diameter	4022.9 mm (see CH2150.260-A001)
Bare mirror clear aperture	diam 3965.4 mm
Central hole	diam 1317.8 mm
Used clear aperture	diam 3934 mm (August 00 after installation of seal CH2922-A001)
Central obscuration	diam 1651 mm (PF cage baffle for f/8 M2)
Light-collecting area	10.014 m^2

F/7.8 secondary ("M2"):

Distance from primary	7494.25 mm
Radius of curvature	9569.6 mm convex
Conic constant	-5.2625
Clear aperture	diam 1295.4 mm

F/14.5 secondary: Retired!

Distance from primary	8.6212e03 mm
Radius of curvature	4.9865e03 convex
Conic constant	-3.044206
Clear aperture

F/30 secondary: Retired!

Distance from primary	9.6871e03 mm
Radius of curvature	2.1153e03 convex
Conic constant	-2.8056
Clear aperture:

Available Foci & Instruments

Prime Focus f/2.87.

Plate scale = 18.0 arcsec/mm or 0.26"/15micron pixel

The only instrument currently available (2012 onwards) at Prime Focus is the Dark Energy Camera [1], follow the link for details.

Ritchey-Chretien (RC) Focus f/8.

Plate scale = 6.56 arcsec/mm

The only instrument currently available at f/8 is COSMOS (Cerro Tololo Ohio State Multi-Object Spectrograph [2]).

This focus is surrounded by a roughly hemispherical Cassegrain Cage. It is equipped with an instrument rotator and offset guider as standard equipment. (WARNING: The rotator may not be functional with all instruments due to interference between the instrument and the surroundings in the Cassegrain Cage.) User supplied instruments may be attached on either the rotator directly or the guider. The nominal focal plane is at a position 6" (15.24 cm) below the Guider mounting surface. The Cass. Cage is entered by means of a walkway that is normally used when the telescope is at the zenith position. Power (110v, 60Hz) is available from an uninterruptible source.