ASTRO-PHYSICS 900GTO Manual de usuario
1
ASTRO-PHYSICS
900GTO GERMAN EQUATORIAL WITH
GTOCP3 SERVO MOTOR DRIVE
ABOUT THIS MANUAL 3
MODEL 900GTO PARTS LIST 4
MECHANICAL SPECIFICATIONS 5
INTRODUCTION 6
Why Polar Alignment is Important 6
ASSEMBLY DIAGRAM 7
BEFORE YOU LEAVE HOME 8
Gross Latitude Adjustment for 900GTO German Equatorial Mounts 8
Attach Pier Adapter to Pier Post (purchased separately) 10
Standard Pier Adapter (900SPA) 10
Precision-Adjust Rotating Pier Adapter with Azimuth Bearing (900RPA) 11
Hi-Lo Latitude Wedge Pier Adapter Assembly (900WDGA) or Wedge (900WDG) 12
AT YOUR OBSERVING SITE 13
Assemble Pier (purchased separately) 13
Attach Polar Axis Assembly to Pier or Tripod 13
Polar Alignment – Part 1 – Rough Alignment 14
Altitude and Azimuth Adjustments - Rough polar alignment 14
Assemble Declination Axis 15
Removing Declination Axis at the End of Your Observing Session 15
Attach Mounting Plate 16
Fixed Mounting Plate Options 16
Losmandy D-Series Compatible Saddle Plates 17
Astro-Physics Dovetail Options 17
Side-by-Side, Vixen Style and Other Plate Options 18
Attach Counterweight Shaft and Counterweights 19
Attach Mounting Rings and Scope 19
CLUTCH KNOBS, BALANCING AND FINE POLAR ALIGNMENT 20
Understanding the R.A. and Dec. Clutch Knobs 20
Balancing Your Telescope 21
First, Balance the Declination Axis 21
Second, Balance the Polar Axis 21
Polar Alignment – Part 2 – Fine Polar Alignment 21
Methods for ne polar alignment 22
Making Precise Altitude and Azimuth Adjustments 23
Fine Altitude Adjustment 23
Tips for Adjusting the Altitude 23
Fine Azimuth Adjustment 23
Precision-Adjust Rotating Pier Adapter with Azimuth Bearing (900RPA) 24
Standard Pier Adapter (900SPA) and Hi-Lo Latitude Wedge (900WDGA) 24
Azimuth Adjuster Knob Locking Screws: 25
2
CABLE MANAGEMENT 26
900 Motor Cables 26
Accessory Cables 26
Optional Accessories to Prevent Cable Snags 26
Example from International Space Station – Amateur Telescope (ISS-AT) Project 27
MOUNT CARE, CLEANING AND MAINTENANCE 28
Care 28
Cleaning and Touch-up 28
Routine Mount Maintenance 28
TROUBLESHOOTING, TIPS AND SUPPORT 29
Troubleshooting and Tips 29
Additional Support 31
STANDARD PIER ADAPTER OF THE 900GTO MOUNT 32
USEFUL DIMENSIONS FOR OBSERVATORY PLANNING 33
CLUTCH PLUG REPLACEMENT FOR 900 OR 1200 MOUNT 34
Construct Your Own Clutch Plug Extraction Tool 35
CHARACTERIZING THE DEC. AXIS MOTIONS 36
ASTRO-PHYSICS MOUNTING PLATE FASTENER CHART 37
3
ASTRO-PHYSICS
900GTO GERMAN EQUATORIAL WITH
GTOCP3 SERVO MOTOR DRIVE
ABOUT THIS MANUAL
This version of the 900GTO Manual was prepared for the production run of mounts that began shipping in November
of 2011. Most of the information in this manual is applicable to all 900GTO’s that have been produced. Some of the
information in this manual was simply not available when the rst 900GTO’s left our factory back in 1998. This includes
information on newer accessories for the mount that weren’t available for the rst production runs. We have also learned
a few things through experience and the suggestions of our customers that have improved the information that is available
in this manual.
You should also note that this manual is actually one component of a three document system. We have always had two
manuals for each mount - one for the individual mount and another manual for the keypad that applied to all mounts.
Starting in the summer of 2011, we further divided the mount manuals to allow us to present the GTO Servo Motor Drive
System in greater detail. Like the Keypad Manual, the GTO Manual is universal to all mounts that use the Astro-Physics
GTO Servo Motor Drive System with the GTOCP3 Servo Control Box. This 900GTO Manual, on the other hand, will cover
the 900GTO’s mechanical features and physical operations.
Please note that we are continually working to improve our products and, as a consequence, some of the drawings,
photographs and descriptions found in this manual may not reect the latest appearance of the product. That being said,
we suggest that all 900GTO owners adopt this manual for regular guidance with their mounts. The benets of the
improved information should easily outweigh the minor differences between mounts from earlier production runs and the
current one. There will be a few things like the included serial cable, the GTOCP3 Servo Control Box and the Heavy Duty
Azimuth Adjuster that owners of older mounts will not have. In a similar fashion, owners of brand new mounts should be
aware that some of the photos that were used in this manual are of
mounts from earlier production runs. You may therefore see some slight
differences whether you have a brand new mount, or an earlier mount,
but none of these were deemed to be of signicance.
As always, we highly recommend the Technical Support Section of our
Web site for the latest information and for future updated versions of this
manual.
A nal note and an apology to our friends in the southern hemisphere.
Many of the instructions in this manual are written entirely from the point
of view of those of us in the northern hemisphere. Since descriptive
terms like left and right are meaningless without a dened point of
reference, we tend to use east and west to avoid ambiguity. The east
and west sides of a German equatorial mount are, of course, reversed
in the southern hemisphere. At one point, our thought was to always
use phrases like the following: “... on the east side (west side in the
southern hemisphere) ...” This quickly became cumbersome and made
the text more difcult to read. For simplicity, we decided to leave many of the explanations in their northern hemisphere
framework. To our southern hemisphere friends: We love you no less and apologize for this unintended slight. We know,
however, that you are all smart enough to make the necessary translation to “down under” appropriate instructions.
Thank you for your understanding.
Please RecoRd the Following inFoRmation FoR FutuRe ReFeRence
Mount Serial Number: ______________________________
Keypad Serial Number: ______________________________
GTOCP3 Serial Number: ______________________________
Purchase Date: ______________________________
4
MODEL 900GTO PARTS LIST
1 Polar axis assembly (right ascension-R.A.) with GTO Servo Control Box (Model GTOCP3)
1 Declination (Dec.) axis assembly
1 14” (12.875” usable) Stainless counterweight shaft (1.875” dia.) with machined, black-anodized, safety stop
1 Y-cable – R.A. portion is 15.25” long and Dec portion is 40.25” long
1 D.C. power cord (cigarette lighter adapter on one end) - 8’ long
1 Serial Cable – Straight-through –15 feet long
1 GTO Keypad controller with 15’ coiled cable, installed Keypad Protector (KEYPRO), and Instruction Manual
1 Hex key set
2 8-32 Thumbscrews (substitute for set screws to allow quick disconnect of GTO control box)
1 PEMPro™ v.2.x – Full Version - Periodic Error Management software for Astro-Physics mounts (CD-ROM)
1 PulseGuide™ by Sirius Imaging – remote control utility for improved guiding (CD-ROM)
In order to assemble your mount fully, you will need the following items sold separately:
●Telescope mounting plate: Many choices to t your telescope and observing needs. See page 16
●20° to 68° latitude: choose either the Standard Pier Adapter (900SPA) or the Precision-Adjust Rotating Pier
Adapter with Azimuth Bearing (900RPA). Either adapter will come with six 5/16 – 18 X 5/8” button head screws for
attachment to the pier, four pier knobs for attaching the mount to the adapter, and the azimuth block for use with the
Heavy Duty Azimuth Adjuster found on all 900GTO mounts produced after August, 2005 and available as an upgrade
for earlier mounts.
●Tropical or extreme polar latitudes (0° to 20° or 68° to 88° North or South): choose the Hi-Lo Latitude Wedge
Pier Adapter Assembly (900WDGA) or the Wedge alone (900WDG) if you already have the knobs and azimuth block.
●8” O.D. pier: Astro-Physics has several heights and styles to choose from.
●Counterweights: 5 lb. (5SCWT), 10 lb. (10SCWT) and 18 lb. (18SCWT) are available.
●Portable rechargeable 12 volt battery pack: Several sizes and types are available from a variety of vendors.
Be sure that your battery pack can supply adequate power for an entire observing session! Please refer to power
requirements in the GTO Servo Motor Drive System manual. We recommend having separate batteries – one for the
mount and one for all other accessories: camera, dew removers etc.
●Regulated Power Supply (110V AC to 12V DC converter): We offer two choices: 13.8 volt 5 amp supply
(PS138V5A) or 15 volt, 10 amp supply (PS15V10A). Both supplies are ltered and regulated.
Many of these items will be discussed throughout these instructions. Several additional options are available:
●Polar Alignment Scope (PASILL4L): (Prior versions sold by Astro-Physics will also work.) Threads into the base of
the polar axis assembly. Many users nd a polar alignment scope useful for zeroing in on the pole quickly, particularly
with telescopes that are not orthogonal to the mount.
●Pier Accessory Trays and Support Bars: Accessory Tray (TRAY08) and/or Eyepiece Accessory Trays (TRAY08H),
both for 8” piers, with Bi-Level (TRAYSB) or Single Level (TRAYSB1) Support Bars. Handy to keep your eyepieces
and other accessories close at hand!
●Counterweight Shaft Options: Longer counterweight shaft (M12601-D) – 19.5” (18.5” usable) stainless steel shaft
or 9” counterweight shaft extension (M12675)
●900 Flat Surface Adapter (900FSA): for attaching one of our pier adapters to your own custom pier or tripod.
●Losmandy Tripod Adapter (LT2APM): for attaching 900GTO to Losmandy Heavy Duty Tripod or Losmandy MA
Meade Field Tripod Adapter.
● Autoguiding Accessories: Various imaging and CCD based guiding congurations can take advantage of the
900GTO’s autoguider port. The autoguider port receptacle (RJ-11-6) uses the industry standard SBIG ST-4 wiring
setup. See the GTO Manual for more.
●Extension cable for keypad: Please call Astro-Physics to obtain a quote on the length of extension cable you need.
For a complete listing of our 900GTO accessories, visit our website – www.astro-physics.com
Note on Encoders: Mounted encoders can no longer be used with the 900GTO (for mounts shipped starting in October,
2005 – beginning serial number 900451) because of the R.A. shaft re-design. They are not needed since the go-to
functions of the mount are so much more accurate. The encoder that is built into the servo motor itself has a resolution of
0.05 arc seconds vs. 324 arc seconds for mounted encoders.
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MECHANICAL SPECIFICATIONS
Construction All CNC machined aluminum bar stock, stainless steel, brass; stainless steel fasteners
Worm wheel - R.A. 7.2” (183 mm), 225 tooth aluminum
Worm wheel - Dec. 6.0” (152 mm), 225 tooth aluminum
Worm gear - R.A. Brass, 0.710” (18 mm) diameter
Worm gear - Dec. Brass, 0.705” (17.9 mm) diameter
Thrust Bearing - R.A. 7.0” (178 mm) diameter
Thrust Bearing - Dec. 6.0” (152 mm) diameter
Axis shaft - R.A. 2.20” (56 mm) diameter
Axis shaft - Dec. 1.75” (44 mm) diameter
Shaft axis bearings - R.A./
Dec.
Each shaft is supported by 5 bearing elements; two preloaded ball bearings and 3 sets of
massive thrust bearings
Latitude range 20 - 68 degrees with or without polar scope attached; (0-20 and 68-88 degrees when using
Hi-Lo Latitude Wedge (900WDG or 900WDGA)
Azimuth adjustment Approximately 15 degrees (+/- 7.5 degrees from center)
Setting circle - R.A. 4-minute increments, pointer, engraved both Northern/Southern, Porter Slip Ring
Setting circle - Dec. 1 degree increments, pointer, Porter Slip Ring
Counterweight shaft 1.875” (48 mm) diameter x 14” (356 mm) long [12.875” (327 mm) usable length], includes
large machined safety stop knob. Optional 9” (229 mm) shaft extension is available.
Weight of mount
Total: 54 lb. (24.5 kg)
R.A. axis / polar fork: 26.5 lb. (12.0 kg)
Dec. axis: 17 lb. (7.7 kg)
Counterweight shaft: 10.5 lb. (4.8 kg)
Capacity of mount
Approximately 70 lb. (31.8 kg) scope and accessories (not including counterweights),
depending on length. Recommended for: Astro-Physics and similar fast refractors up to 180
mm f9, 12” Cassegrains, 12.5” CDKs, 12-14” Ritchey-Chretiens. These are only guidelines.
Some telescopes are very long for their weight or heavy for their size and will require
a larger mount. Remember also that imaging requirements are more rigid than visual
observation.
Instrument mounting
interface Refer to the mounting plate section of the manual on page 16.
Pier adapter base
7.730” (196.34 mm) diameter. The base is part of the chosen pier adapter - either the
Rotating Pier Adapter (900RPA), the Standard Pier Adapter (900SPA), or the Hi-Lo Latitude
Wedge (900WDGA or 900WDG). The desired pier adapter must be purchased separately.
For a complete listing of the servo control, power, and periodic error specications, please see the
GTO Servo Motor Drive System Manual.
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INTRODUCTION
The 900GTO German equatorial was designed to meet the needs of the advanced observer who requires a mount with
maximum strength and rigidity and minimum weight. The excess material in both axes has been carved out while retaining
a heavily ribbed structure for internal strength and rigidity. A unique dovetail was machined into the mating surfaces of the
R.A. and Dec. axes. This feature allows quick and easy assembly in the eld without any tools.
The advent of modern CCD cameras and telescopes with high-resolution optics has placed greater demands on the
ability of mounts to do their part to achieve precision tracking and guiding. At the same time, the mount should be easy
to use with adjustments and setup procedures that are straight-forward and accurate. We have done everything possible
to eliminate the frustrations and limitations inherent in a lesser mount and so put the fun back into the hobby of amateur
astronomy.
The 900GTO employs the reliable and sophisticated Astro-Physics GTO Servo Motor Drive System. This system uses
precise Swiss DC servo motors under the control of the remarkable GTOCP3 Servo Control Box. The GTOCP3 is truly the
“brains” of the system taking your wishes as expressed through an external device like the Astro-Physics GTO Keypad, a
computer, or even some wireless devices, and translating those wishes into actions taken by the mount.
A full range of mount operations is available from the included GTO Keypad. This advanced keypad’s features allow you
to slew automatically to objects in a wide range of databases, as well as any R.A. / Dec. coordinates. A large selection of
common names for stars and other objects makes your selection a snap. Keypad operation is simple and intuitive.
Various additional options such as PulseGuide™ software (included with the mount) and our fully supported AP V2
ASCOM driver are also available to make the connection between you - the astronomer, and the servo system versatile
and straightforward.
The 900GTO’s control and performance options will be further enhanced by the upcoming Astro-Physics Command Center
(APCC). This exciting software is in its last phase of beta testing at the time of this writing, and the rst ofcial release will
be available soon. APCC will fully address all the capabilities of the 900GTO, and will add enhancements not currently
available anywhere else. More information on all the mount control options can be found in the separate Astro-Physics
GTO Servo Motor Drive System Manual.
The 900GTO also includes a full version of PEMPro v.2.x, and as an added bonus, all 900GTO mounts will come pre-
loaded with the custom-tted PEMPro™ corrections from our extensive individual testing that is performed on each and
every mount. While the native, uncorrected, periodic error of your 900GTO will be 7 arcseconds or less, it will have been
reduced even further to maximize performance without auto-guiding.
The 900GTO is equally at home in a permanent observatory or as a portable mounting for remote star parties thanks to
the ease with which the two axes come apart. This is the perfect mount for a mid-sized refractor, Newtonian, Cassegrain
or astrograph. Whether you enjoy visual astronomy exclusively or
plan an aggressive astrophotography or CCD imaging program,
this mount will allow you to maximize your night out under the
stars.
In order to fully enjoy your rst night out, we recommend that
you familiarize yourself with the assembly and basic operation
of the mount indoors. The temperature will be comfortable,
the mosquitoes at bay, and you’ll have enough light to see the
illustrations and read the manuals.
Why Polar Alignment is Important
Polar alignment compensates for the Earth’s rotation.
If you were to take a long exposure photograph with Polaris (often
called the North Star) in the center of the eld, you would discover
that all stars seem to revolve around Polaris. This effect is due to
the rotation of the earth on its axis. Motor driven equatorial mounts
were designed to compensate for the earth’s rotation by moving
the telescope at the same rate and opposite to the earth’s rotation.
When the polar axis of the telescope is pointed at the celestial
pole (polar aligned) as shown in the diagram, the mount will follow
(track) the motions of the sun, moon, planets and stars. As a result,
the object that you are observing will appear motionless as you
observe through the eyepiece or take astrophotos.
7
ASSEMBLY DIAGRAM
Please read all instructions before attempting to set up your 900GTO mount. The model 900 is very rugged, however like
any precision instrument, it can be damaged by improper use and handling. Please refer to the following illustrations. The
parts are labeled so that we can establish common terminology.
The following terms and abbreviations are used interchangeably in these instructions:
● polar axis = right ascension axis = R.A. axis = R.A. housing
● declination axis = Dec. axis = Dec. housing
8
BEFORE YOU LEAVE HOME
Since most of us must set up our instruments in the dark, in the cold or while battling mosquitoes, a bit of preplanning
and organization is important. There are a few simple things that can be accomplished in the comfort of your home before
heading outside.
Gross Latitude Adjustment for 900GTO German Equatorial Mounts
Degree ranges specied below apply to mounts shipped starting in May 2006. Older mounts will have
slightly different latitude ranges unless they were upgraded with the taller polar fork.
The latitude range of the 900 mount is approximately 20-68 degrees. Since most astronomers typically observe within one
latitude range, this rst adjustment is made just once, if at all. Prior to shipment, we preset the mount to your latitude range
for your convenience. If you travel to another observing location, determine the latitude of your observing site and make the
appropriate adjustment. If you live in or plan to travel to tropical locations that are 0 to 20 degrees latitude north or south,
or extreme polar sites that are between 68 and 88 degrees north or south, we recommend our Hi-Lo Latitude Wedge Pier
Adapter Assembly (900WDGA). Pier Adapters are discussed fully later in the manual.
The four positions for the altitude adjustments have the following approximate ranges:
52 degrees to 68 degrees latitude - top position
41 degrees to 59 degrees latitude - third position
30 degrees to 45 degrees latitude - second position
20 degrees to 34 degrees latitude - bottom position
How to change the position of the altitude adjuster
1. Use only the R.A. axis. DO NOT attempt
to make these adjustments with the decli-
nation axis in place and certainly not with
an instrument fully mounted.
2. Loosen both altitude-locking knobs about
1 turn.
3. Locate the side of the polar axis that does
not have the black motor/gear housing
box. Loosen (about 1 turn) the polar axis
pivot screw and altitude adjuster bar xing
screws on this side only. With your hand,
push the polar axis upwards so that the
altitude-locking knobs are positioned at
the top of the altitude adjustment slots
(this is the maximum altitude position).
Some resistance will be felt with this
operation as you are pushing against the
weight of the polar housing and the resist-
ance of the remaining polar axis pivot screw (which has not been loosened).
4. Before attempting to move the altitude adjuster bar, you must tighten the altitude-locking knob on the motor/gear
housing side. This will prevent any downward movement of the polar axis
during positioning of the altitude adjuster bar.
5. While supporting the altitude adjuster bar, remove the two altitude adjuster bar
xing screws that support it on each side (4 screws in all), but keep the two
ends of the bar in contact with the side of the mount, don’t remove it com-
pletely (this tip is for your convenience).
6. Determine the latitude range that you need and position the altitude adjuster
bar so that the hole that is marked “A”, as shown in the diagram, is located at
the appropriate hole position numbered 1-4 in the lower diagram. Note that
hole “A” is located at the rounded part in the center of the altitude bar. Hole
“A” is the “latitude hole.”
7. Attach two of the screws (one on either side of the adjuster bar) through the
appropriate altitude adjustment position hole and into hole A of the adjuster
bar, but do not tighten. Rotate the altitude adjuster bar around this pivot
9
point until the corresponding hole lines up. Consult the labeled photo to determine which hole of the altitude adjuster
bar should be used. Be very careful since the holes marked C and B are very close to one another, as are the holes
marked D and E. The incorrect hole may appear to line up, however it will be slightly off. If you try to attach at the incor-
rect hole, you may strip the threads of the altitude bar. The correct hole will orient the adjuster to be roughly perpen-
dicular to the axis once the axis is lowered into place.
8. Once you have located the correct hole, insert the remaining two screws, and lightly tighten so that you still have some
ability to wiggle the bar.
9. Note that the altitude adjustment knob is at-
tached to a threaded rod that travels through
the altitude adjuster bar. Turn the knob so
that the altitude adjuster bar is positioned
approximately in the middle of the threaded
rod. You should see about half of the
threaded rod protruding from both sides of
the altitude adjuster bar. This will allow you
to move the mount fully within the altitude
range.
10. At the end of the threaded rod mentioned in
the last step, you will see a small brass
altitude adjuster thrust pad. This is the part
that will come in contact with the polar axis
as you ease it back into position. Loosen the
altitude-locking knob (motor/gear side) and
lower the polar axis so that it rests comfortably on this pad. The threaded rod should be positioned at a right angle to
the polar axis housing. Firmly tighten the altitude adjuster bar xing screws.
11. Turn the altitude adjustment knob to raise or lower the polar axis to your approximate observing latitude. Tighten the
altitude locking knobs with nger pressure only. You do not need to tighten with the hex key.
12. Firmly tighten both polar axis pivot screws with the hex key.
Otros manuales para 900GTO
1
Tabla de contenidos
Otros manuales de Telescopio de ASTRO-PHYSICS
ASTRO-PHYSICS
ASTRO-PHYSICS 400 Manual de usuario
ASTRO-PHYSICS
ASTRO-PHYSICS 400GTO Manual de usuario
ASTRO-PHYSICS
ASTRO-PHYSICS GTOCP2 Manual de usuario
ASTRO-PHYSICS
ASTRO-PHYSICS 1200 Manual de usuario
ASTRO-PHYSICS
ASTRO-PHYSICS 3600GTO Manual de usuario
ASTRO-PHYSICS
ASTRO-PHYSICS 400QMD Manual de usuario
ASTRO-PHYSICS
ASTRO-PHYSICS PASILL4 Manual de usuario
ASTRO-PHYSICS
ASTRO-PHYSICS Mach1GTO Manual de usuario
