Astro-Physics
1600GTO Mount Options, Upgrades and Spare Parts

As time goes on, this page will outline a variety of options and spare parts for the 1600GTO German Equatorial Mount.

Absolute Encoder Options

In order to meet the needs of the most demanding astro-imagers and researchers, we have integrated the optional Renishaw RESOLUTE Absolute Encoders into our 1600GTO mount. These encoders and readheads comprise a true absolute non-contact optical encoder system, which offers the latest in technological advances to ensure accurate and reliable performance in the field. What will this mean for you? Near perfect periodic error correction and your mount will never be lost, which will result in greater productivity and hassle-free imaging sessions. Your mount will be invisible, as it should be.

Consider these features when the absolute encoders are installed in both axes:

  • Absolute encoder knows the exact position of the gear angle of the mount when the power is applied.
  • No separate homing sensor is needed. Homing can be set to any gear angle via a simple software command.
  • Adjustable software slewing limits based on the position of the gear angle allow you to safely image several hours past the meridian.
  • Virtual elimination of Dec. backlash symptoms when auto-guiding. Absolute encoders will close the loop in both RA and Dec axes for very accurate guiding. The response, especially in Dec will be instant and will eliminate all backlash delays during reversal of the motors. This is important when using a long focal length scope.
  • High immunity to dirt, scratches and light oils to withstand real-world observatory conditions.
  • Sealed readhead for high reliability in harsh environments.
  • Integral set-up LED on readhead for quick set-up and instant “health check” any time.
  • Built-in position-checking algorithm constantly monitors calculations for ultimate safety and reliability.
  • Low temperature version available.

RESOLUTE uses a unique single optical absolute track (a world first) combined with sophisticated optics. The readhead acts like an ultra fast miniature digital camera, taking photos of the coded scale of the encoder ring. Photos are analyzed by a high-speed DSP to determine absolute position. The built-in position check algorithm actively checks every reading. Advanced optics and position determination algorithms are designed to provide low noise and low sub-divisional error. The result is unparalleled performance.

Specifications

  • One-piece 4” diameter stainless steel ring with a single track, true absolute scale marked directly onto the periphery. High accuracy graduations ensure outstanding metrology and reliability.
  • Resolution: 67 million pulses per rotation, 0.019 arc second per pulse.
  • Accuracy is +- 3 arc seconds over the entire 24 hour, 360 degree rotation. +- 0.2 arc sec per hour typical accuracy.
  • RESOLUTE Absolute Encoder:
    Operating: 0 degrees C to +80 degrees C (32 F to +176 F)
    Storage: -20 degrees C to +80 degrees C (-4 F to +176 F)
  • RESOLUTE ETR (Extended Temperature Range) Encoder:
    Operating: -40 degrees C to +80 degrees C (-40 F to +176 F)<
    Storage: -40 degrees C to +80 degrees C (-40 F to +176 F)
  • Operation down to -40 degrees C (-40 degrees F) in non-condensing environments is guaranteed by Renishaw. However, we have not tested the extreme ends of the range ourselves. The encoder is also tough enough to survive the physical punishment of harsh environments with solid steel ring scales. NOTE: If you plan to operate the mount in severe cold temperature environments, please contact Astro-Physics regarding special lubrication requirements that may be needed..

Unguided exposure: 10 minute (600 seconds)M106

This test exposure was taken with the 175EDF refractor at F8.3 at 1452mm FL, 9 micron pixel size. Click on the thumbnail to view the full image including the enlarged section, which shows the pinpoint star image.

Unguided exposure: 5 minute (300 seconds)

This image is the result of six separate 5 minute unguided test exposures taken with the 175 StarFire EDF. Unguided imaging was necessary because the H-alpha filter basically wiped out all star signals needed for the internal guide chip. One of many reasons that unguided imaging is a great advantage. Click on the thumbnail to view the enlarged image.


Unguided exposure: 10 minute (600 seconds)

This image consists of four ten minute exposures that were done at 1200 mm focal length with an SBIG STL-1100. It was done in Luminence filtration. No separate guiding was done. Click on the thumbnail to view the enlarged image.

 

We feel that even longer exposures with refractors are feasible since, typically, they only have a tiny amount of flexure compared to mirror scopes. This is particularly true if the object is straight up. However, since many optical systems have inherent flex issues and possible mirror movements and tracking rates vary from one part of the sky to another, APCC (Astro-Physics Command Center Pro version software, purchased separately) will provide additional corrections to make unguided imaging a reality for a wide variety of optical systems, assuming that the error is repeatable and can be modeled. Tests at the University of Hawaii with our 3600GTOPE equipped with an R.A. encoder and using the APCC Pro version with the APPM pointing model (beta version) already have shown that unguided exposures are possible with large Ritchey-Cretien imaging scopes. This will greatly enhance their research program.

Software Controls for the Absolute Encoders

The commands related to the Absolute Encoders can be issued through the easy-to-use interface of the  Astro-Physics Absolute Encoder Utility (Windows-based) provided on a CD-ROM. This program utilizes the Astro-Physics ASCOM V2 driver.

Order Options

The 1600GTO can be used with the R.A. encoder only or both R.A. and Dec. If you order the R.A. encoder only, you will gain the advantage of minimizing your tracking error. However, you will not have the position angle and homing features since information from both axes is required.

You may order your 1600GTO with the Absolute Optical Encoder system installed and adjusted at Astro-Physics or you may order the kit at a later date to install yourself. This kit will include the stainless steel encoder ring precisely installed into the 1600GTO adapter, the readhead assembly, cables and the auxiliary GTOAE control box to install on your mount. The system will be tested as a whole prior to shipment to ensure that all components are functioning properly. In order to complete the assembly, a little manual dexterity is required to position the screws in a restrictive space. Total assembly time is estimated at 20-30 minutes for both encoders. This kit can be retrofit onto your 1600GTO when you are ready to take advantage of their capabilities. We will provide detailed instructions to guide you through this process.

R.A. Absolute Encoder and Readhead with GTOAE Control Box and Cables
What’s Included:
  • R.A. Absolute Encoder installed and aligned in adapter ring
  • R.A. Readhead with wire harness aligned in adapter
  • GTOAE Control Box
  • Cable from GTOAE Control Box to GTOCP3 Control Box
  • Cable from GTOAE Control Box to Interface at rear of the R.A. axis
  • Power Cable
  • Control Box Clamp for GTOAE
  • CD with Absolute Encoder Utility (Windows-based)
  • All required fasteners
Order
R.A. Absolute Encoder and Readhead, installed at Astro-Physics (16AE-R-I)
R.A. Absolute Encoder and Readhead Kit, installed by customer (16AE-R-KIT)
16AE-R-I$4,130.00 DecemberAdd 16AE-R-I To My Cart
16AE-R-KIT$4,280.00 DecemberAdd 16AE-R-KIT To My Cart


R.A. Absolute Encoder and Readhead, low temperature version, installed at Astro-Physics (16AE-RL-I)
R.A. Absolute Encoder and Readhead Kit, low temperature version, installed by customer (16AE-RL-KIT)
16AE-RL-I$4,500.00 DecemberAdd 16AE-RL-I To My Cart
16AE-RL-KIT$4,650.00 DecemberAdd 16AE-RL-KIT To My Cart

Dec. Absolute Encoder and Readhead
Note: Must be used in conjuction with the R.A. Encoder System; cannot be used alone.
What's Included:

  • Dec. Absolute Encoder installed and aligned in adapter ring
  • Dec. Readhead with wire harness aligned in adapter
  • All required fasteners
Order
Dec. Absolute Encoder and Readhead, installed at Astro-Physics (16AE-D-I)
Dec. Absolute Encoder and Readhead Kit, installed by customer (16AE-D-KIT)
16AE-D-I$2,830.00 DecemberAdd 16AE-D-I To My Cart
16AE-D-KIT$2,980.00 DecemberAdd 16AE-D-KIT To My Cart


Dec. Absolute Encoder and Readhead, low temperature version, installed at Astro-Physics (16AE-DL-I)
Dec. Absolute Encoder and Readhead Kit, low temperature version, installed by customer (16AE-DL-KIT)
16AE-DL-I$3,200.00 DecemberAdd 16AE-DL-I To My Cart
16AE-DL-KIT$3,350.00 DecemberAdd 16AE-DL-KIT To My Cart


Note: The Astro-Physics Command Center (APCC) software is not included as part of this package. It will be available as an optional purchase.

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Flat Surface Adapter for 1600GTO and all 1200 Mounts (1612FSA)

As of July 2012 , the Flat Surface Adapter (formerly part # 1200FSA) has been upgraded to include four additional thru-holes for more secure attachment to a flat plate with the larger 1600GTO and its payload in mind. It also includes "N" and "S" engraving to ensure that the base of your mount will be oriented in the correct direction when it is inserted.

 

 

1600GTO
The base of the 1600GTO slips directly into the 1612FSA. There is no need for an extra pier adapter, as the 1600 incorporates the functionality of the Precision-Rotating Pier Adapter into its base. The extended latitude range of the 1600 also eliminates the need of a polar wedge.

1200 (all versions)
Use this adapter for these applications:

The 1612 Flat Surface Adapter is black-anodized, precision-machined aluminum.

Attach to flat surface
The Flat Surface Adapter bolts onto the flat surface on the top of your pier or tripod. Your pier's top plate should be a minimum of 9.75" in diameter. The 1612FSA itself is 10.345" in diameter. It adds 1.265" to the height of your mount.

The bolt circle for attaching the 1200 Flat Surface Adapter to your pier is 9.230” in diameter. Please refer to the PDF link provided on the diagram to the right for detailed information on attachment preparation.

The holes for mounting the 1612FSA to your flat surface are counter-bored to accept the head of standard ¼” socket head cap screws (13/32” or 0.406” diameter). This allows the 1600 base or 1200 Pier Adapter to sit in the Flat Surface Adapter without interference. Because installations will vary, we do not provide the screws for mounting the Flat Surface Adapter to your pier or tripod.

Attach to 1200 Hi-Lo Latitude Wedge
Match four holes and bolt the 1612FSA in place. Then, your Pier Adapter simply slips in (just as it fits into our pier) and you fasten from the side with the six screws and washers provided with the Pier Adapter for your 1200 mount.

Fasteners are not supplied.

Note: You may wish to consider purchasing our Flat Pier Plate with Flat Surface Adapter for 1600GTO and all 1200 Mounts (1612FSA-FP) if you are fabricating your own pier and need a flat plate to fit into the top. Some modification may be required to fit your pier I.D.

1612FSA$140.00 in stockAdd 1612FSA To My Cart

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Flat Pier Plate for 10" ATS and other non-Astro-Physics piers (1612FP)

This Flat Pier Plate (1612FP) has been machined to the specifications of the Advanced Telescope System (ATS) 10” pier.  It is sized to fit directly into the pier without modifications and provide a mounting surface for our 10” Flat Surface Adapter (1612FSA) (previously 1200FSA).  It will add 0.75” to the height of the pier.

Owners of 1100GTO and 900 mounts will be pleased that additional holes have been drilled and tapped for our 8” Flat Surface Adapter (119FSA) (previously 900FSA).  This is of interest to imagers who are looking for the most robust and stable pier for their larger scopes setups. 

The bottom, pier-inserting portion of this plate has additional thickness to allow custom machining in order to fit a smaller inside diameter pier.  Please refer to the PDF schematic for dimensions.

Pier options:

  • Use with the 10” ATS pier (no modification required)
    The base of the 1612FP has already been machined per the specifications provided by ATS to fit into their piers without further modification.
  • Use with other piers (may require custom modification)
    Machine the bottom portion of this plate to fit the I.D. of your pier, if necessary. Please refer to the diagram to determine if your pier is suitable.

Top attachment options:

  • Attach 10” 1612FSA (use existing tapped holes)
  • Attach 8” 119FSA (use existing tapped holes)
  • Attach custom  mount adapter (machine custom tapped holes)

If you intend to attach an 1600GTO or older 1200 mount to the ATS pier, then it is best to choose the combination Flat Surface Adapter with Flat Pier Plate (1612FSA-FP).  It is a two-part adapter that combines both the 1612FSA and the 1612FP. 

Fasteners included:
1/4-20 x 3/4" (8) - attaches 1612FSA or 119FSA to Flat Pier Plate (1612FP)
5/16-18 x 5/8" (6) and washers - attaches 1612FP to ATS pier

Note:  Since the bottom of the flat plate is designed to fit into the 10" ATS Piers, the diameter (9.450") is too small to be used in the Astro-Physics 10" Portable Piers.

1612FP$220.00 in stockAdd 1612FP To My Cart

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Flat Surface Adapter with Flat Pier Plate for 1600GTO and all 1200 Mounts - For 10" ATS and other non-Astro-Physics piers (1612FSA-FP)

If you are ordering a 10" ATS pier for your 1600GTO, you will need to order this adapter to interface the pier post with the base of your mount. You may also consider it if you are fabricating your own pier for either the 1600GTO or any 1200 mount. You do NOT need this adapter for the 10" Astro-Physics Piers.

This item is constructed of two machined aluminum parts bolted together - a thick flat plate and our Flat Surface Adapter for 1600GTO and 1200 Mounts (1612FSA). Since the bottom of the flat plate is designed to fit into the 10" ATS Piers, the diameter (9.450") is too small to be used in the Astro-Physics 10" Portable Piers. This adapter adds 2.015" to the height of the ATS pier.

The lower flat-plate section of this adapter is also drilled and tapped so that the 119FSA (formerly part # 900FSA) can be attached. This allows the 1100GTO and all 900 mounts to be attached to your 10" pier.

Use with 10" ATS Piers and 1600GTO

  • The base of the 1612FSA-FP has already been machined per the specifications provided by ATS to fit into their piers without further modification. The 1600GTO will fit directly into the top portion of the 1612FSA-FP.

Use for Other Piers and 1600GTO

  • Machine the bottom portion of this plate to fit the I.D. of your pier. The base of the 1600GTO will fit directly into the top portion of the 1612FSA-FP.
  • The Particle Wave Monolith will receive this adapter directly, provided that it has the reported 9.50" inner diameter specification.

Use for Other Piers and 1200 Mounts

  • Machine the bottom portion of this plate to fit the I.D. of your pier. Please refer to the diagram to determine if your pier is suitable.
  • These adapters for the 1200GTO will fit into the top portion: Precision-Adjust Rotating Pier Adapter (1200RPA), Standard Pier Adapter (1200SPA), or 1200 Hi-Lo Latitude Wedge (1200WDG or 1200WDGA).

Fasteners are supplied for attaching the 1612FSA-FP to ATS or other similar pier.

1612FSA-FP$350.00 in stockAdd 1612FSA-FP To My Cart

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Copyright © 2012, Astro-Physics, Inc. - All Rights Reserved
This page was last modified: November 22, 2014

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