| Weight
of telescope including science instrument: |
circa
20,000 kg |
| Configuration: |
Cassegrain-telescope
with Nasmyth focus, permanent access to science instrument from
cabin |
| Structural
layout: |
CFRP-structure in
dumbbell shape with trusswork metering tube |
| Rotation
isolation system: |
Hydrostatic
bearing with 2 ring segments, 1.2 m diameter, 10-30 bars pressure |
| Rotation
drive system: |
Coarse drive for
elevation and fine drive (brushless DC spherical segment motors)
for elevation, cross-elevation and line-of-sight (L.O.S.) |
| Vibraton
isolation system: |
12 springs/dampers
around the hydrostatic bearing in longitudinal and tangential
directions |
| Primary mirror (PM): |
2.7 m diameter, 2.5
m effective aperture, lightweighted ZERODUR structure on 18-point
whiffle-tree support, PM ratio f/1.28, aluminum coated |
| Secondary
mirror (SM): |
SiC material,
352 mm diameter, aluminum coated |
| SM functions: |
Focus, alignment,
chopping (2-axis in arbitrary directions, offset, three point,
stationary) |
| Tertiary
mirror (TM): |
2 flat
exchangeable mirrors, dichroic (gold coated) and non-dichroic
(aluminum coated) |
| System focal ratio: |
f/19.6 |
| Wavelength
range: |
0.3 um
to 1,600 um |
| Unvignetted field
of view: |
8 arcmin |
| Ranges
of motions: |
Elevation
15-70 degrees (20-60 degrees unvignetted), cross-elevation and
L.O.S. ± 3.0 degrees |
| Diffraction limited
wavelengths: |
Greater or equal
to 15 microns |
| Image
stability (goal): |
0.2 arcsec
rms for focal plane tracking |
| Total
emisivity of telescope: |
15% at
10 microns with dichroic tertiary
10% at 10 microns with aluminized tertiary |
| Temperature
of telescope: |
240K |
