|
Economical High Performance Robotic
Telescope Systems
20" Folded
Newtonian |
- Aperture Range: 20" and 24" on equatorial fork
mounts.
- Design Applications: CCD imaging, CCD
photometry.
- Optical System: F/5 Folded Newtonian, fully
baffled, featuring easy collimation points for the primary, secondary and the
image plane, also includes rapid focus adjustment mechanism on the secondary
allowing for quick instrumentation changes at the image plane.
- Usable Focal Plane Diameter: 1.5", suitable for
CCD sensors up to 24x36mm.
- F/ratio: F/5, F/5.7 with Paracorr.
- Optical Tube Assembly: Three part construction
featuring a DEC axis center box, removable front truss/secondary mirror
assembly and removable rear cell/primary mirror assembly.
- Fork Mount: Welded steel construction, computer
designed for ultra-low flexure.
- R.A.-DEC Perpendicularity: ±2 arc-seconds,
adjustable.
- Telescope Pedestal: Welded steel construction,
±2.5º azimuth and altitude adjustments.
- R. A. Drive Shafts/Bearings:
| (20") |
3" diameter cold rolled steel shaft with 3" tapered
roller bearings |
| (24") |
3-1/2" diameter cold rolled steel shaft with 3-1/2"
tapered roller bearings |
- Dec. Drive Shafts/Bearings: NOTE: Tapered roller
bearings are available on the DEC axis for NEO or other specialized tracking
applications.
| (20") |
3" diameter cold rolled steel shaft with 3" ball
bearings |
| (24") |
3" diameter cold rolled steel shaft with 3" ball
bearings |
- Drive System: Hybrid Band-Worm Drive (Patents
Pending)
- Drive System Electronics: ComSoft PC-TCS stepper
motor control system. ComSoft PC-TCS servo system is also available for $10,000
more.
- Standard Accessories: TeleVue Paracorr®
offering near diffraction limited imaging over a 1" diameter focal plane, Optec
TCF-S Focuser at focal plane for automated focusing.
- Lower Cost compared Ritchey-Chrétien
optical systems.
- Pricing, excluding applicable taxes, shipping and
installation costs; Manufacturing Time:
| (20" FN) |
$120,000.00 |
10 months |
| (24" FN) |
$160,000.00 |
10 to 12 months |
|
Product Description
Our ObservatoryScope Folded Newtonian product
line is specifically designed to provide large aperture imaging solutions for
amateurs and institutions on a tighter budget. These instruments are designed
for automated observations of comets, asteroid patrols, variable star programs,
supernovae searches and tricolor deep space imaging applications. Additionally,
the Folded Newtonian is ideally suited for remote operation, via the Internet,
where the instrument is located at a remote observatory facility and the
operator is located elsewhere.
Optical Performance
Coma Corrector
Performance Graphs by Al
Nagler |
The folded Newtonian optical system, consisting
of a parabolic primary and an optical flat secondary, is the real secret to the
affordability of these instruments. An optical flat is used not only to fold
the conventional Newtonian design into a much more compact optical tube
assembly, but also to allow for much more extensive baffling (as with a
Cassegrain) than would ever be possible with a conventional Newtonian. Baffles
are located around the primary mirror, around the secondary mirror and in front
of the image plane. Several computer optimized field stops are provided for in
the baffle tube located in front of the image plane.
These instruments are similar to a conventional
fully baffled Cassegrain system since the optical path is similar. The major
difference is that the focal plane is located in
front of the primary mirror, rather
than behind the primary. The included TeleVue Paracorr® coma
corrector / field flattener provides for a 40mm diameter field of
view with a flat image plane. The accompanying drawings, prepared by Al Nagler,
shows the optical performance both for a F/4 (green box) and F/5 (red box)
Newtonian optical system. The blue line indicates the pixel size of a CCD
camera with 11 micron pixels. Note the extremely good performance obtained with
an F/5 optical system. Performance is almost diffraction limited and well below
an 11 micron pixel size across a very large field radius!
The optical system offers several advantages in
addition to significantly reduced cost. Advantages are much wider fields of
view and the placement of the imaging equipment close to the center of gravity
of the declination axis. The location of the imaging equipment allows for quick
changes to the imaging equipment without having to rebalance the instrument!
Additionally, the Folded Newtonian is much faster at F/5, when compared to a
conventional Cassegrain, and provides a significantly wider field of view.
These are desirable advantages for a variety of imaging applications that
require wider fields of view.
Pointing and Tracking
Performance
ObservatoryScope Folded Newtonian Systems provide
exceptional, observatory class pointing and tracking capabilities. Our
guaranteed minimum performance specifications for our Folded Newtonian
telescopes are shown below.
| Tracking Precision: |
<1 arc-second MAX** over 300 seconds; <10 arc-seconds
MAX over 1 hour |
| Raw Pointing Precision: |
<15 arc-seconds MAX to 30° from zenith; <40
arc-seconds MAX to 60° from zenith |
| Calibrated Pointing Precision: |
<5 arc-seconds MAX to 15° from zenith; <12
arc-seconds MAX to 60° from zenith |
| Pointing Repeatability: |
<3 arc-second MAX for an offset move of 5 degrees; <6
arc-seconds MAX for an offset move of 30 degrees |
| DEC Backlash: |
<1.5 arc-seconds MAX, repeatable |
** ObservatoryScope uses MAX (maximum
error) instead of RMS for all performance specifications.
Drive System
Specifications
| Hybrid Band-Worm Drive System
for 20" to 24" Aperture Telescopes: |
| Equivalent Gear Diameter: |
Performance equivalent to a 40" diameter, 2520 tooth
worm gear. |
| Primary Drive Disk: |
28" diameter sand cast aluminum precision bored and
turned on an industrial lathe. |
| Secondary Drive Disk: |
4" diameter precision bored and turned from aluminum
bar round stock. |
| Primary-Secondary Disk Coupling: |
Belt Technologies 1-1/8" width, 0.015" thick, 301HY
high yield stainless steel precision fabricated band. |
| Worm Gear: |
5.625" diameter, 7075 aluminum worm gear, 360 tooth,
anodized aluminum worm. |
| Band Drive to Worm Drive Coupling: |
1" diameter stainless steel shaft supported by tapered
roller bearings. |
| Band Drive Ratio: |
7:1 |
| Worm Drive Ratio: |
360:1 |
| Worm-Motor Ratio: |
3:1 |
| Overall Reduction Ratio: |
7560:1 |
| Steps / Motor Revolution: |
1600:1 using x8 microstepping and 1.8 deg/step stepper
motors. |
| Steps / Telescope Revolution: |
12,096,000:1 yielding 9-1/3 steps per arc second or
0".107 arc second per step. |
| Required Motor Torque: |
<1 ounce-inches of torque with the telescope in
balance; <4 ounce-inches of torque with the telescope 20 foot-pounds out of
balance. |
| Periodic Error: |
less than 1.0 arcsecond MAX without PEC
correction. |
| Tooth to Tooth Error: |
less than 1.0 arcsecond MAX. |
| Drive System Backlash: |
less than 1.5 arcsecond MAX. |
| Full Worm Cycle: |
Approximately 34.192 seconds. |
|
Product Summary
In summary, an ObservatoryScope Folded Newtonian
Robotic System is an ideal, cost effective, instrument for many amateurs and
institutions. Advantages are reduced cost and large fields of view suited for a
variety of imaging applications such as asteroid / supernova
patrols, deep space imaging and comet observations. The only disadvantage is
the inability to use these instruments visually. |
