Basic Optical Data
-
| Primary Mirror |
| Radius of curvature |
|
21336.0 mm concave |
| Conic constant |
|
-1.09763 |
| Mirror diameter |
|
4011.6 mm (Drawing 2106-E1) |
| Bare mirror clear aperture |
|
diam 4002.6 mm |
| Central hole |
|
diam 1324 mm |
| Used clear aperture |
|
diam 3797 mm (Measured by Phil Massey) |
| Central obscuration |
|
diam 1651 mm (PF cage) |
| Light-collecting area |
|
9.182 m² |
| PF Mosaic Focus Calibration |
|
1.043 microns/unit |
|
| F/7.8 Secondary Mirror |
| Distance from primary |
|
7492.0 mm |
| Radius of curvature |
|
9643.0 mm convex |
| Conic constant |
|
-5.2951 |
| Clear aperture |
|
diam 1191.6 mm (CHECK) |
| Secondary to RC focus |
|
9306.2 mm |
| Instrument rotator to RC focus |
|
152.4 mm |
| Effective focal length |
|
31258.7 mm |
| Focus Calibration |
|
0.991 microns/unit |
- Download 4-m f/7.6 ZEMAX file
|
|
| F/15 Secondary Mirror |
| Distance from primary |
|
8634.5 mm |
| Radius of curvature |
|
5000.2 mm convex |
| Conic constant |
|
-3.09014 |
| Clear aperture |
|
742.7 mm |
| Secondary to SQIID focus |
|
10895 mm |
| Instrument rotator to SQIID focus |
|
598.7 mm |
| Effective focal length |
|
57160.3 mm |
- Download 4-m f/15 ZEMAX file
|
Prime Focus (f/3.1) Corrector and ADC Prisms
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| Opto-Mechanical Assembly - 4 Meter Prime Focus Corrector |
 |
| The 4-m prime focus corrector is described in Jacoby, Liang, Vaughnn, Reed, and Armandroff
(1988 SPIE, 3355, 721).
|
Slew Time
-
 |
| Time measured from the beginning of a slew motion until the telescope comes to rest (dots)
and the 4MAPS stabilizes (X) for slew motions from 1 to 20 degrees in both RA and DEC (Thanks to Dave
Summers).
|
|
4MAPS - 4 Meter Active Primary System
-
4MAPS Manual (NOAO only)
Risley Prisms - Cass Focus
-
| Risley Prisms |
Deployable |
| Clear Aperture |
172 mm |
| Total Thickness |
104 mm |
| Front Element to R-C Focus |
931 mm |
| Clear Field f/7.8 |
45.3 mm = 298 arcsec |
Telescope
-
Cassegrain Cage Mechanical Data
* datum=back of primary mirror cell
| Component | Weight(lb) | Moment (in-lb)* |
| Instrument rotator |
960 |
6720 |
| Guider |
640 |
11520 |
| Allowable instrument |
1350 |
|
| Total load |
2950 |
72570 |
additional weight information
| Optical Layout Figure | Automatic Guider Bolt Pattern |
|
|
| Cassegrain Cage Clearances | Cassegrain Instrument Rotator |
|
|
| |
| Cassegrain Guider Assembly | |
|
|
Dome
-
There are some old (and old-fashioned paper) enormous drawings of the dome and environment, but they are like ancient papyrus and very crowded with information.
|
