RC20-140FT
|
Optical System
|
Ritchey-Chretien
|
| Primary Diameter |
20.0" |
| Specular Precision |
1/25, or better, wave front
RMS |
| Mirror Substrate |
Near-zero expansion ceramic |
| Focal Ratio |
f/8.1 |
| Image Scale |
49.9 arc sec/mm |
| Tube Diameter |
24.5" |
| Tube Length |
54" |
| Tube Cooling |
12 V DC fans |
| Material |
Open Truss XZe Carbon Fiber© |
| Focuser Tube I.D. |
4.2" |
| Available Back Focus |
10.5" |
| Secondary Diameter |
7.25" |
| Sec. Focus Range (electric
standard) |
12" |
| Focus Stabilization, w. Al tube |
Invar 36 |
Mounting
|
OGS-140 Fork
|
| Aux. Instrument Cap. |
175 lbs. |
| Tracking Precision |
<1 arc sec RMS (after modeling) |
| Pointing Precision |
<30 arc sec RMS (after modeling) |
| R. A. Drive |
18" 360 tooth worm gear & ball
bearing worm |
| DEC Drive |
15" 360 tooth worm gear & ball
bearing worm |
| Shafts |
6.0" Ø (140mm at R. A. bearing
ends; 75mm at DEC ends) |
| Motors |
Five-phase nano-step or servo |
| Axis Intersection |
72" from base of pier (at 40°) |
| Fork Swing Clearance |
21" |
| Weight (system) |
925 lbs. |
| R. A. Counterweights |
2 x 2.5 lbs. |
| Pier |
32" high, typically (custom
heights available) |
| Fasteners |
18-8 stainless steel |
