• Declination Axis. Complete redesign of the declination axis with new thrust bearings and preloaded shaft bearings. This allows the mount to operate with excellent guiding precision when the telescope is upside down for imaging many hours past the meridian.
  A special upgrade (part # 900DU) will be available for existing 900 mounts that will incorporate improved bearings, the new spring-action motor bracket, and other changes.
• Azimuth adjustors. This one-piece assembly makes azimuth adjustment easier and more accurate for precise polar alignment in your observatory or in the field. The heavy-duty construction and integrated one-piece design results in smooth control of the azimuth axis. Large left and right adjuster knobs are graduated for precise control of azimuth position angle. The small graduations are 1.3 arc minutes per graduation; long graduations are 6.5 arc minutes per graduation. The size of the knobs makes them easy to turn with very little torque required, even with the mount fully loaded.
  Available to upgrade previous mounts. Refer to 900 Upgrades and Spare Parts for photos and detailed description of the Azimuth Adjuster .
• Polar forks. Height was increased to allow tightening of the rear knob. Eliminated the sharp corners to prevent cords from catching.
  Available to upgrade previous mounts. Refer to 900 Upgrades and Spare Parts for photos and detailed description of the Polar Fork .
• Gearbox. Improved the gear profiles of the motor gearbox, so slewing is noticeably quieter. Amount of backlash delay in the motor gearbox has been reduced so that declination reversal occurs almost instantly. The gears are made by the same company that supplied NASA with the drive gears on the Spirit and Opportunity Mars Rovers. They have also produced components for the space station.
  Not available for previous mounts at this time.
• Motor bracket. Has built-in spring-action to keep the worms loaded at the proper setting. Available only as part of the 900 Declination Upgrade (part # 900DU) due to the way the bracket attaches. It is not available as a separate upgrade item.
• Additional internal enhancements that enhance the overall performance.

Pier Adapter Options

• Precision-Adjust Rotating Pier Adapter with Azimuth Bearing (900RPA). Not included with mount, purchased separately. Rotates on a bearing surface. This allows you to lock the mount down with no need to loosen the base during azimuth adjustment. Especially recommended for use in the field. Will be available to upgrade previous mounts. Refer to 900 Upgrades and Spare Parts for a more detailed description.

• Standard Pier Adapter (900SPA). Not included with mount, purchased separately. This pier adapter is essentially the same as the adapter that we have offered standard with the 900 in the past, however it has a slightly taller (1.2", rather than 1.1") azimuth adjuster block to accommodate the new azimuth adjuster assembly. Note: If you just want to upgrade your present pier adapter with the new block, order part #M12020-A, which you can install easily yourself. Refer to 900 Upgrades and Spare Parts for photos and more detailed description.

GTOCP3 Servo Motor Control Box
Although the GTOCP3 control box looks the same on the outside as the prior GTOCP2 model, the internal circuit boards have been redesigned to allow expanded functionality and provide additional protection of the circuit. The command language has been expanded to allow additional functions. As always, our command language is available to write your own program.

These functions cannot be added to the earlier GTOCP1 and GTOCP2 control boxes; they are available only in this new version. However a complete GTOCP3 control box can be purchased as an upgrade for all prior GTO mounts - 400GTO, 600EGTO, 900GTO and 1200GTO.

• All new electronics. All input lines are protected against heavy static discharge with transorbs. Larger internal chip to allow additional functions. FCC and CE certified.
• Drainage holes. Two threaded drainage holes are drilled into the lower part of the control box housing so that excess moisture can drain easily. This may prove useful if you live in an area with high humidity.
• Timed Move. If the “:Me#" or “:Mw#" or “:Mn#" or “:Ms#" commands are issued with an integer between 1 and 999, the controller will move in the specified direction for the number of milliseconds specified. No respective quit command is necessary. The total displacement will be determined by the current guide/center rate setting. This allows PC based programs to introduce precise motion without the complication of providing accurate time separation between the move and quit commands.
• Continuous variation of both RA and Dec tracking rates. The tracking rate in either RA or DEC can be set to any arbitrary value using the “:RR sxxx.xxxx#" or “:RD sxxx.xxxx#" commands. “s" is the sign “+" or “-“. In the RA axis, the rate is superimposed on the sidereal rate. The rate is normalized to 1x sidereal. This simplifies the scheduling of the mount trajectory for tracking planets, comets, satellites, etc. The command “:RTx#" is retained. PulseGuide , the software program by Ray Gralak of Sirius-Imaging, takes advantage of this feature.
• Arbitrary centering rate. By specifying the centering rate using a lower case “c" rather than an upper case “C", (“:Rc64#" rather than “:RC1#") the centering rate becomes equal to the value specified as a multiple of 1x. The range is 1 to 999.
• PEM memory. PEM memory is accessible to external software programs in order to smooth out and modify the curve. PEMPro by Sirius-Imaging supports directly reading from/writing to the PE storage locations. This allows more accurate programming of the mount's PEM (that is, the mount does not have to interpret move or autoguider commands). Also, programming is significantly quicker than waiting for one worm cycle's worth of playback (6 min 24 seconds) as is the case for the GTOCP2. Also, PEMPro reads parameters and calculates the mount's worm period (useful if you have a non-Astro-Physics mount with the GTO Control System, available only through OEM manufacturers).
• The Time-of-Day clock overflows properly from 23:59:59 to 0:00:00. On overflow, the date also advances. A read date command was also added, “:GC#".
• Solid electronic connection. The controller is no longer susceptible to uncontrolled motion/"racing" resulting from input power fluctuations, “bounces" or glitches. In prior control boxes, this could occur when the power cord was plugged in and the connection was incomplete for a split second.
• Horizon check. Bug is fixed. This only impacts people who write their own programs. The keypad and planetariums all have their own independent horizon check routine which did not rely on this code in the control box chip.

Purchase the GTOCP3 Control Box as an upgrade for your current GTO mount. Link contains details that you need to know.
GTOCP3 Control Box - Features and Specifications.

• Larger chip memory capacity on new circuit board. Will allow us to add more features to the firmware program in the future. All keypads with serial # 1491 and later numbers have this larger chip.
• LED fiber optic backlit panel. Does not require a transformer as did the prior EL backlit panel, so they will operate more quietly. Keypads with this feature also have the updated circuit board. All keypads with serial # 1568 and higher have this backlit panel.
• Epoxy coated elastomeric keys.The keypad graphics will retain their appearance longer. All keypads with serial # 1568 and higher have elastomeric keys.
• Additional internal improvements that take advantage of advancements in technology.

Copyright © 2005, Astro-Physics, Inc. - All Rights Reserved
This page was last modified: March 30, 2006

Astro-Physics, Inc.
11250 Forest Hills Road, Machesney Park, IL  61115, U.S.A.
Phone: 815-282-1513   Fax: 815-282-9847