Astro-Physics
Technical Support - Current Products

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Instruction Manuals and Sheets - Current Products
Refractors
GTO German Equatorial Mounts
Mount Accessories
Telescope Accessories

Refractor

• Care of Your Astro-Physics Refractor (9-4-14) - PDF Document
• Lens Cleaning Formula and Instructions (2-20-18) - PDF Document
• Mounting 92mm f5 or f7 to TeleVue Gibraltar Mount with 7" Sliding Bar (09-10-02)
• 130mm EDF Gran Turismo Assembly Instructions (07-18-08) - PDF Document
• How to Install Your New Focuser (06-10-04)
• Rapid Cooling Effects on Oil-Spaced Triplets (2-25-09) - PDF Document

GTO German Equatorial Mounts

• General Information that Applies to all German Equatorial Mounts
• Latitude Dimension Calculator for Current Mach1GTO, 900GTO, 1100GTO, 1200GTO, 1600GTO and 3600GTO Mounts (10-22-2012) - Excel Spreadsheet for determining certain critical dimensions and choosing an appropriate pier height for your system; now includes metric dimensions and centimeter/inches calculator.
• Quick Start & Workflow Guide (01-01-2025) - PDF document summarizing physical and software setup for all Astro-Physics GTO mounts.
• Balance to Optimize Guiding - PDF document illustrating the best way to balance a mount.
• Drift Alignment R.A. Correction Method - PDF document providing a step by step method to achieve high precision alignment within 45 degrees of the zenith. This method provides quick alignment for the prime imaging area. A CCD camera and guide software are required.
• Making A PE Curve with PEMPro - PDF document illustrating the step by step making of a corrective PE curve.
• Orthogonality Correction - PDF document illustrating the best way to correct orthogonality in scope mounting.
• Park Positions Illustrated - PDF document showing Park 1, 2, 3, and 4 positions.
• Decimal Degrees (DD.ddddd) to Degrees/Minutes/Seconds (DD*MM:SS.s) Converter (6-16-2010) - Excel Spreadsheet for quick conversion of location coordinates. Also includes Hours RA to Degrees.
  
  
• Mach2GTO German Equatorial
• Mach2GTO with CP5 Control Box (10-17-23) - PDF document. Note that the Astro-Physics GTO Control System has been given its own separate manual - see below.


• 1100GTO German Equatorial
• 1100GTO with GTOCP4 Control Box (March 2021) - PDF document - Current Version for mounts shipped starting in March 2021 and all previous 1100GTO mounts produced. We strongly recommend that ALL 1100GTO owners adopt this version as their manual (note that some aspects may not apply to earlier versions of the mount). Owners of older 1100GTOs can benefit from all that we have learned over the years by using this manual. Information on accessories, the servo system and polar alignment will be of particular value. Note that the Astro-Physics GTO Servo Drive System has been given its own separate manual - see below.
• 1100GTO Auto-Adjusting Gearbox - No More Worm Meshing! (05-30-18) - PDF document. **Use this document for worm mesh information instead of the Gear Mesh page in printed manuals dated before February, 2017.**
• 1100GTO with GTOCP3 Control Box (11-06-14) - PDF document.
• Adjustments to Remove Worm Gear Backlash (10-24-14) - PDF document
• 1100 AE Hardware Connections with GTOCP3 (8-27-15) - PDF document
  


• 1150GTO German Equatorial
• 1150GTO with GTOCP6 Control Box (09-10-25) - PDF document - Current Version for mounts shipped starting in September 2025.Note that the Astro-Physics GTO Control System has its own separate manual - see below.


• 1600GTO German Equatorial
  • 1600GTO with GTOCP4 Control Box (05-12-24) - PDF document - Current Version for mounts shipped starting in February 2024 and all previous 1600GTO mounts produced. We strongly recommend that ALL 1600GTO owners adopt this version as their manual (note that some aspects may not apply to earlier versions of the mount). Owners of older 1600GTOs can benefit from all that we have learned over the years by using this manual. Information on accessories, the servo system and polar alignment will be of particular value. See page 3 for more information about this manual. Note that the Astro-Physics GTO Servo Drive System has been given its own separate manual - see below.
  • 1600GTO with GTOCP4 Control Box (01-10-24) - PDF document.
  • 1600GTO with GTOCP4 Control Box (05-30-18) - PDF document.
  • 1600GTO Auto-Adjusting Gearbox - No More Worm Meshing! (05-30-18) - PDF document. **Use this document for worm mesh information instead of the Gear Mesh page in printed manuals dated before February, 2017.**
  • 1600GTO with GTOCP3 Control Box (9-05-14) - PDF document
  • 1600GTO with GTOCP3 Control Box (9-12-13) - PDF document.
  • Adjustments to Remove Worm Gear Backlash (10-24-14) - PDF document
  • 1600 AE Hardware Connections with GTOCP3 (8-27-15) - PDF document
  
  
• GTOCP4 Control Box
• Astro-Physics GTO Servo Drive System - Model GTOCP4 (January 2024) PDF document - Current Version for all mounts with GTOCP4 Servo Control Boxes. We strongly recommend that all owners of Astro-Physics and OEM GTO mounts with GTOCP4 control boxes adopt this manual as their primary reference for the GTO Servo Drive System. Owners of older GTO mounts may also find useful information in this manual, but be aware that not all the information will apply to the older servo control systems. This is an ongoing project that we will try to keep updated with all the latest developments. Please check back often and compare the date following the link to the date on your copy of the manual to stay abreast of the latest developments.
• Astro-Physics GTO Servo Drive System - Model GTOCP4 (February 2020) PDF document.


• GTOCP5 Control Box - For the Mach2GTO only
• GTOCP5 Micro-Step Servo System Operating Instructions December 2023 - PDF document
• GTOCP5 Micro-Step Servo System Operating Instructions August 2020- PDF document


• GTOCP6 Control Box - For the1150GTO only
• GTOCP6 Control System Operating Instructions September 2025 - PDF document


• GTOCP4/CP5/CP6- additional useful files
• WiFi Poll for GTOCP4 and GTOCP5 Ethernet Application (2016-0711) NOTE: This application is deprecated and has been replaced by the AP GTO Utilities found at the top of this page. To find current IP addresses and other network information. Requires AP V2 ASCOM Driver and a serial or USB connection to the control box. NOTE: We had removed the link to this .exe file earlier since it had caused a problem with firewalls and anti-virus programs. It is now back on the website as a ZIP file. Normal Windows extraction is fine.
• Default IP Address Calculator and Latitude/Longitude Coordinate Converter This link has two handy tools:
  ** IP Address Calculator - will take the CPx serial number and return the default IP address for the device. While the Wi-Fi poll and FindMounts look at your actual system and find devices, this only does a basic calculation without looking into your computer.
  ** Latitude/Longitude Coordinate Converter - Enter local coordinates in decimal degrees, and press Calculate Coordinates to get the Degree:Minute:Second format.
• Find Mounts (VFM-01-04) to find current GTOCP4 IP addresses and other network information. Works for any computer - Windows, Mac or Linux running Java. Requires the Java Runtime Environment from Oracle (already found on many computers). Normal Windows extraction is fine. A purchased copy of WinZip is NOT required.
• Pinouts for Auto-guider (only for control boxes with ST-4 port)
• Auto-guider Tester (only for control boxes with ST-4 port)
• GTO Control Box RS232 Serial Port Pinout (02-28-05) - PDF document
• Pier Side Diagram (unfinished draft - more info to come 09-19-12) - PDF document


• Keypad Manual and Technical Documents
  • GTO Keypad Controller Manual, Version 5.14 (08-09-25) - For GTOCP4 and GTOCP5 with newer version keypad buttons, and and GTOGTP6. Keypad serial # must be 1565GTO or HIGHER due to memory requirements. - PDF document
  • GTO Keypad Controller Manual, Version 5.13 (07-19-24) - For GTOCP4 and GTOCP5 with newer version keypad buttons. Keypad serial # must be 1565GTO or HIGHER due to memory requirements. - PDF document
  • GTO Keypad Controller Manual, Version 5.012 (01-10-24) - For GTOCP4 and GTOCP5 with newer version keypad buttons. Keypad serial # must be 1565GTO or HIGHER due to memory requirements. - PDF document
  • GTO Keypad Controller Manual, Version 5.010 (06-20-22) - For GTOCP4 and GTOCP5 with newer version keypad buttons. Keypad serial # must be 1565GTO or HIGHER due to memory requirements. - PDF document
  • GTO Keypad Controller Manual, Version 4.19.5 (10-08-21 ) - For any GTOCP1, GTOCP2, GTOCP3 or GTOCP4 control box. Keypad serial # must be 1565GTO or higher due to memory requirements. - PDF document
  • GTO Keypad Controller Manual, Version 4.19.3 (08-22-19) - For GTOCP1, GTOCP2, GTOCP3 and GTOCP4 with P01-xx version firmware. Do not use with GTOCP4 with P02-01 or later firmware or GTOCP5 control box - PDF document
  • Keypad Maintenance Instructions (7-3-17) - PDF document
  • Install Pigtail Harness on New Battery (10-04-21) - PDF document
  • Daylight Savings Change in Keypads (3-6-18) - PDF document
  • Setting GMT (UTC) in Keypads (3-12-18) - PDF document
  • Keypad Resetting Solutions (6-18-2003) - PDF document
    
  
  
• Mount Troubleshooting - For additional troubleshooting tips, check the mount and keypad manuals.
  • Declination Axis Backlash Tests - PDF document. These instructions explain how to use Maxim DL software as a tool for characterizing any problems with the Declination axis movements of your mount. However, Ray Gralak's PulseGuide software offers an easier and more extensive evaluation procedure. PulseGuide is available as a free download.
  • Slewing Your Mount in Below Freezing Temperatures (12-24-04) - PDF
  • Diagnosing a Motor Stall (06-22-10) - PDF document. This is the text from a post to the ap-gto users group that outlines a sytematic approach to diagnosing a motor stall in an Astro-Physics GTO mount.
  • Potential Causes of RA Drift (09-27-19) - PDF document
  
  
• Command Protocol
  • Astro-Physics Command Protocol for GTO Mounts (GTOCP1 and GTOCP2 control boxes)- Shipped prior to 11-13-00 (06-16-01)
  • Astro-Physics Command Protocol for GTO Mounts (GTOCP1 and GTOCP2 control boxes)
    - Version C, KC, D, KD, E, E1 and KE1 (07-06-06) - PDF document
  • Astro-Physics Command Protocol for GTO Mounts (GTOCP3 and GTOCP4 control boxes) (04-26-19) - PDF document.

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Mount Accessories

• Instructions
  • Right-Angle Polar Alignment Scope (RAPAS) (10-06-25) - PDF document.
  • Polar Alignment Telescope (PASILL3) (09-24-02) - PDF document. This is a previous model, shipped from August 2002 until July 2005.
           Why doesn't my polar alignment scope look like the one illustrated?  (Click here)
  • Instructions for Using the 12" Sliding Bar for Losmandy D-Series Dovetail Saddle Plates (SBD12) - (03-13-09) - PDF Document
  • Losmandy Polar Scope Polarity Test Instructions (9-11-08) - PDF document
  • Using Losmandy Dovetail Plates with Astro-Physics Rings (07-17-08) - PDF document
  • Using Your Traveler or Stowaway with 13.5" Losmandy Universal Plate (04-25-03) - PDF document
  • Attachment Options for Adapter to Attach Losmandy HD or MA Tripod to Astro-Physics Mount (LT2APM) (11-02-10) - PDF document.
  • Mounting Plate Recommendations for the 130mm f6.3 StarFire 'Gran Turismo' (12-30-08) - PDF document.


• Dimensions and Useful Information
  • Mounting Plate Fastener Chart (7-12-2018) - PDF document
  • 8" Portable Pier Footprint Dimensions - PDF document
  • 400/600E Tripod Adapter Dimensions (ADATRI) - PDF document
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Telescope Accessories
Diagonals & Binoviewer
• Mark V Binocular Viewer from Baader Planetarium (11-20-08) - PDF document
• 2" MaxBright Diagonal (11-02-06) - PDF document
Focusers
• 2.7" Focuser Dimensions (06-02-05)
• 2.7" Astro-Physics Thread Specifications (07-10-08) - PDF document
• Installing Feather Touch Focuser Upgrade - 2.7" Traveler and 4" Focusers (10-07-05) - PDF document
• 4" Focuser Dimensions with Adapters (05-22-07) - PDF document
Imaging - Photo
• Installing the CCD Adapter to Use the 2.7" or 4" Field Flatteners with a CCD Camera (07-28-08)- PDF document
• Astro-Physics 2.7" to 6x7 Outer Bayonet Adapter - Exploded Diagram and Instructions (08-27-08) - PDF document
• Adapters to Attach SBIG STL Series CCD to Astro-Physics 2.7" and 4" Prime Focus Field Flatteners and to the 2.7" to 6x7 Outer Bayonet Adapter: Short - 1.58" (ADA671) and Long - 1.93" (ADA672) - Instructions (08-28-08) - PDF document
• Attaching the Astro-Physics Field Flattener to Your Pentax 6x7 Camera (07-30-02) - PDF document
• Astro-Physics Prime Focus Field Flatteners (07-30-02) - PDF document
  • Exploded diagram showing the field flatteners with a variety of accessories.
• Astro-Physics Photo-Visual Telecompressor (01-18-10) - PDF document
  • Exploded diagram showing the Photo-Visual Telecompressor with a variety of accessories.
• Astro-Physics CCD Telecompressor (02-06-06) - PDF document
  • Exploded diagram showing the CCD Telecompressor with a variety of accessories.
• Astro-Physics Photo-Visual Telecompressor (27TVPH) and CCD Telecompressor (CCDT67) Spacing, Compression Calculation and Coverage (03-12-09) - PDF Document
• 0.76x CCD Telecompressor Corrector Spacing Requirements - for 175TCC, 160TCC and 155TCC (06-12-12) - PDF document
• 175 and 160 CCD Field Flattener Spacing Requirements - for 175FF, 160FF (06-12-12) - PDF document
Miscellaneous
• Using the TeleVue StarBeam and Qwik Point with QBASE or Sliding Bars (01-18-10) - PDF document
Solar
• Baader Planetarium AstroSolar™ Film Care and Safety (1-26-17) - PDF document
• Making an Inexpensive Filter Cell for BAADER AstroSolar™ Material (1-26-17) - PDF document
• Making an Off-Axis Filter Cell for BAADER AstroSolar™ Material - PDF document