ASTRO-PHYSICS 1200 GERMAN EQUATORIAL WITH GTO SERVO MOTOR DRIVE Model GTOCP2 February 26, 2002
ASTRO-PHYSICS 1200 GERMAN EQUATORIAL WITH GTO SERVO MOTOR DRIVE MODEL 1200GTO PARTS LIST – MODEL GTOCP2 5 FEATURES AND SPECIFICATIONS 5 INTRODUCTION 6 Why Polar Alignment is Important Compensation for the Earth’s rotation 6 6 ASSEMBLY INSTRUCTIONS 7 Before You Leave Home Before You Leave Home Gross Latitude Adjustment Attach Pier Adapter to Pier Post Assemble Pier (purchased separately) Assemble Polar Axis Assembly to Pier or Tripod Altitude and Azimuth Adjustments - Rough polar alignment Assemble
MOUNT MAINTENANCE AND ALIGNMENT 19 TROUBLESHOOTING 19 INSTALLATION OF ENCODERS AND ENCODER HOUSINGS -1200 MOUNT 21 Fitting Declination Encoder Housing Fitting Right Ascension Encoder Housing Periodic Maintenance 21 22 22 4
ASTRO-PHYSICS 1200 GERMAN EQUATORIAL WITH GTO SERVO MOTOR DRIVE MODEL 1200GTO PARTS LIST – MODEL GTOCP2 1 1 1 1 1 1 1 1 1 1 2 Polar axis assembly (right ascension-R.A.) with Servo Box GTOCP2 Declination (Dec.) axis assembly Pier top adapter with six (6) 5/16-18 x 5/8" button head screws with washers (these may be attached to your pier post if you ordered one) Stainless counterweight shaft with washer stop and black plastic knob (knob has 5/16 thread) Y cable – R.A. portion is 12.
INTRODUCTION The 1200 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 field without any tools.
ASSEMBLY INSTRUCTIONS Please read all instructions before attempting to set up your 1200 mount. The Model 1200 is very rugged, however like any precision instrument, it can be damaged by improper use and handling. Please refer to Diagram 2 for an illustration of the mount. 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.
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 few simple things that can be accomplished in the comfort of your home before heading outside. Gross Latitude Adjustment The total latitude range of the 1200 mount is approximately 20-68 degrees with 4 adjustment positions.
6. Determine the latitude range that you need (refer to Diagram 3) and position the hole that is marked “A” in Diagram 5 at that location. Note that this hole is located at the rounded part of the altitude bar. 7. Attach two of the screws (one on either side of the adjuster bar), but do not tighten. Rotate the altitude adjuster bar around this pivot point until one of the other holes lines up. Insert the remaining two screws. Lightly tighten so that you still have some ability to move the bar. 8.
Assemble Polar Axis Assembly to Pier or Tripod In order to track the motion of astronomical objects, the polar axis must be positioned so that an imaginary line drawn through the center of the axis points toward the celestial pole. At this stage of the assembly process, you want to position the mount so that it points roughly north. 1. Remove the four (4) hand knobs on the pier top adapter and keep them close at hand. 2.
Assemble Declination Axis 1. Do not have your telescope or counterweights connected to the Dec. axis assembly for either assembly or disassembly of the Dec. and RA axes. 2. Position the R.A. axis as shown in Diagram 7 with the pocket "A" at the top, opposite the altitude adjuster knob. Firmly tighten R.A. clutch knobs. 3. During shipment, the Dec. axis assembly lock knobs will be fully screwed into the Dec. axis.
Attach Mounting Plate (purchased separately) Several mounting plates are available for the 1200 mount. If you own more than one instrument, you may need more than one plate. Follow the appropriate directions for the plate(s) that you have. 18" FLAT MOUNTING PLATE (FP1800) This plate is 18" long and 7.5" at its widest point in the center. The width of the plate tapers to 5.5" at each end. Four pairs of keyhole slots that measure 3.2" between centers are provided. The two inner pairs are 13.
Attach Mounting Rings (purchased separately) Our flat and ribbed plates are constructed with keyhole slots at the location where your mounting rings attach. This feature enables you to partially loosen the screws on your rings just enough to insert them into the larger part of the keyhole, then slide the rings to the narrow part and tighten them with a hex key. You can even accomplish this with the rings on the scope, although this maneuver may be difficult to accomplish with a large, heavy instrument.
OPERATION OF THE MOUNTING R.A. and Dec. Damper Knobs The R.A. and Dec. damper knobs are not intended as axis locks. They should be tightened with light finger pressure so that a slight resistance can be felt when pushing an unclutched axis by hand. This really adds to the "feel" at the end of the scope with the drives adjusted correctly. The purpose of the damper knob is to add a bit of friction to the shaft so that gusty winds do not move the axes in their bearings.
3. Position the R.A. axis so that the counterweights are in their "lowest" position i.e. the declination axis assembly is in the meridian (this is the usual way that German equatorials are depicted, as shown in diagram 2.) 4. Loosen the tube mounting rings and slide the tube up and down for balancing. This is best done with the tube in the horizontal position. 5.
SERVO MOTOR DRIVE GTO Control Box – Model GTOCP2 The GTO control box contains all of the circuitry to drive the two servo motors and the logic required to navigate the sky. It will be operational and track at the sidereal rate when connected to both motors of the mount and a power source.
RS-232 Connectors These serial port connections are used to connect your mount to your PC computer. You must provide your own straightthrough (non-crossing) cables with a 9-pin (DB9) male connector to interface with the GTO panel. We have provided the locking posts to secure the cable firmly. If your serial cable does not have a 9-pin connector, you can use a gender changer or adapter to convert it.
Prevent the Cables from Tangling The movement of the mount across the meridian during slewing functions is calculated so that the cables will not tangle if they are set up properly. In addition to the motor and power cables that are provided with the mount, you may have additional cables for other accessories. These may be powered from the GTO Control Panel or from another power source. We suggest that you position your cabling carefully to avoid a tangled mess.
MOUNT MAINTENANCE AND ALIGNMENT Under normal operating conditions, minimal maintenance is required. Every 12 months the clutch knobs (4 for Dec. and 4 for R.A.) should be removed and 1 or 2 drops of light oil (3 in 1 household oil) should be put in the exposed hole. If the R.A. and Dec. axes are attached together for a long time in outside conditions (i.e. in a permanent observatory) then the mating surfaces should be lightly oiled or greased - if you expect to get them apart again after 10 years.
Recommended Reading from our Staff: The Backyard Astronomer's Guide, Terence Dickinson and Alan Dyer, Camden House Publishing, 1991 The authors, both former editors of Astronomy magazine, offer practical insight into astronomical equipment, finding your way around the sky, polar alignment, using setting circles, and astrophotography. This book provides excellent explanations and is well organized and illustrated. All About Telescopes, Sam Brown, Edmund Scientific Company, 1975.
INSTALLATION OF ENCODERS AND ENCODER HOUSINGS -1200 MOUNT 1200ENC (purchased separately) Parts List: 1 Right Ascension (R.A.) Encoder housing (black anodized) 1 Declination (Dec.) Encoder housing (black anodized) 1 R.A. Axis Adapter (clear anodized - silver colored), labeled R.A. 1 Dec. Axis Adapter (clear anodized - silver colored), labeled Dec. To install your encoders, first remove the telescope from your mount. Remove your declination counter weight(s) and declination counterweight shaft.
Fitting Right Ascension Encoder Housing If the encoders were purchased with the 1200 mount, it is likely that the right ascension axis adapter and encoder housing have already been installed. Please continue to read these directions since you may need to remove and reinstall the encoders if you use a polar alignment scope. Since the polar axis telescope and R.A. axis adapter thread into the same location, you will need to switch back and forth between them as needed.
