Astronomy Specialist




Testar Australia is a technical assistant dealer for 10 Micron. Our staff has been trained at the 10 Micron factory to provide assistance, repairs and maintenance on their products.


The GM4000 HPS mount, now in the new M2 version, is built for observatories with instruments up to 150kg (excluding counterweights). It is ideal for remote observation sites and its loading capacity allows for mounting instruments such as 300mm diameter refractors, 400mm diameter Newtonian reflectors, 600mm diameter Cassegrains and so on. Movements are driven by two servo brushless motors, with timing belt reduction having zero-backlash. Both axes feature a classic worm – wormwheel pairing. The wormwheels are made of bronze (B14), with a diameter of 330mm and 430 teeth in right ascension and a diameter of 244mm and 315 teeth in declination. The worms are made of alloy tempered steel with a diameter of 32mm. The axes are made of alloy steel with a diameter of 85mm (right ascension) and 80mm (declination), for the maximum rigidity.

The electronics are housed in an easily detachable housing (control box), mounted above the right ascension axis to obtain the best accessibility. The connections of the mount and keypad security lock screws and only one cable runs from the control box to the mount. The axes feature a 60mm diameter hole allowing for the passage of instrument cables. This effectively solves the problem of entangling cables and damaging instruments, especially for remote observatories. The mount is powered with low voltage, requiring a maximum power of about 100W. This makes it possible to use the mount in locations with limited power available. The GM4000 HPS can be completely controlled by using the included keypad without requiring an external PC.

The keypad is built to maintain the maximum readability in all lighting conditions. Both the display and the ergonomic keys, allowing for the use of gloves, feature a red backlight. A heater keeps the display warm for usage below freezing temperatures. The mount can be controlled by using the most common software packages by connecting it to a PC with a RS‑232 serial port or Ethernet connection, via the 10Micron ASCOM driver or the Meade compatible command protocol. Further, a dedicated software (also included with the mount) can be used to create a “virtual keypad”, precisely replicating the functions of the physical keypad. The RS‑232 port can also be used to control an external dome. This flexibility makes the GM4000 HPS an ideal mount for observatories and remote observing sites.

The object database contains many star catalogues and deep‑sky objects up to the 16th magnitude. Solar system objects can be tracked so that their motion is compensated with respect to the stars. You may load orbital elements of comets, asteroids and artificial satellites into the mount so that these objects can be tracked directly.

Pointing is made accurate through the usage of a model containing up to 100 stars, which allows for the correction of the classical polar alignment and conic errors as well as the most important flexure terms of the optical tube. In this way it is possible to obtain a pointing accuracy up to 15 arcseconds RMS. The same model can be used to obtain the maximum tracking accuracy, compensating also for the atmospheric refraction (depending on the local atmospheric pressure and temperature). A series of auxiliary functions is provided to help the user to a quick alignment of the mount to the celestial pole. You may also save and recover the alignment data of different observing sessions. This function is very useful if you have many instruments in different setups, each one requiring different flexure corrections. Tracking through the meridian, a typical problem with German mounts, is solved to allow for tracking of up to 30° past the meridian (configurable) in both directions. In this way any object can be tracked for at least four hours.

The tracking accuracy makes auto-guiding not necessary for many uses. The absolute encoders on both axes allows to obtain a typical tracking error below 1 arcsecond.

It is possible to auto-guide anyway by using the ST4‑compatible port or through the serial/Ethernet connection with a guide rate configurable from 0.1x to 1x. The guide rate can be automatically corrected for the declination of the target, so that there is no need to recalibrate the auto-guide when observing at different declinations. A dedicated connector on the control box panel is used for remote switching on and off. The instrument can be electronically balanced without disengaging the worm from the wormwheel. The mount can be parked in different user‑defined positions. The serial RS‑232 port can be used to control an external dome, avoiding the need for a dedicated external PC. Once configured with your instrument parameters, the firmware is able to make all the calculations required to position the dome slit in front of your optical tube for almost all instrument configurations.

The GM4000 can be supplied also in a special version for very low temperature operations: ask our team if interested.




German Equatorial Mount

Weight (mount)

125 kg – without accessories

Instrument payload capacity

150 kg

Latitude range

20° – 70°

Azimuth fine adjustment range

+/− 10°

Counterweight shaft

60 mm diameter, stainless steel, weight 13 kg


R.A. 85 mm diameter, alloy steel
Dec. 80 mm diameter, alloy steel


Pre-loaded tapered roller bearings

Worm wheels

R.A. 430 teeth, 330 mm diameter, B14 bronze
Dec. 315 teeth, 244 mm diameter, B14 bronze

Worm gears

Diameter 32 mm, tempered alloy steel, grinded and lapped

Transmission system

Backlash-free system with timing belt and automatic backlash recovery


2 axes servo brushless

Power supply

24 V DC

Power consumption

~ 1.5 A at sidereal speed
~ 4 A at maximum speed
~ 5 A peak

Go-to speed

Adjustable from 2°/s to 8°/s (6°/s in a.r.)
Special version 48 V DC from 2°/s to 12°/s (10°/s in a.r.)

Pointing accuracy

< 20” with internal multiple-stars software mapping

Average tracking accuracy

< +/− 1" typical for 15 minutes (< 0.7" RMS)
with internal multiple-stars software mapping and compensation of flexure and polar alignment errors

Security stop

+/− 30° past meridian in r.a. (software)
+/− 35° past meridian in r.a. (mechanical)
+/− 170° interval in dec. (software)
+/− 172,5° interval in dec. (mechanical)

Operational temperature range (standard)

- 15° C to + 35° C

Storage temperature range

- 40° C to + 50° C

Special operational temperature range

Optional, for very low temperature operations (until -35°C / -31°F): see options for more details

Communication ports

RS–232 port; GPS port; auto-guide ST-4 protocol port; Ethernet port.


Stars: by name, Bayer designation, Flamsteed designation, Bright Star Catalogue, SAO, HIP, HD, PPM, ADS, GCVS. Deep-sky: M, NGC, IC, PGC, UGC limited up to mV = 16. Solar system: sun, moon, planets, asteroids, comets, artificial satellites. Equatorial and altazimuth coordinates. User defined objects, fast slewing positions.

Firmware features

User defined mount parking position, 2‑stars and 3‑stars alignment function, up to 100 alignment stars for modeling, correction of polar alignment and orthogonality errors, estimate of average pointing error, storage of multiple pointing models, sidereal, solar and lunar tracking speed adjustable on both axes, declination-based auto-guide speed correction, adjustable horizon height limit, pointing and tracking past meridian,, assisted balance adjustment, manual or GPS based time and coordinates setting, dome control via RS-232, configurable atmospheric refraction, network settings, comets and asteroids filter, multi-language interface. Remote assist via Internet connection.

PC control

Remote control via RS-232 or Ethernet; proprietary ASCOM driver or Meade compatible protocol; update of firmware and orbital elements of comets, asteroids and artificial satellites via RS-232 or Ethernet; virtual control panel via RS-232 or Ethernet. Wi-Fi included to control the mount via tablet, smartphone etc.



GM4000 HPS II Mount includes:

  • GM 4000 HPS II mount with built-in precision absolute encoders
  • Control box with on-board intelligence (Linux-processor),V. 2
  • HPS version firmware, stand alone system (no PC required)
  • Professional hand control unit with graphic display and temperature control – 10M5030
  • Cables
  • Counterweight shaft
  • WiFi option included.

GM4000 HPS II Catalogue


HPS Mount Comparison Chart


GM4000 HPS Accessories Diagram


GM4000HPS Sizes


HPS Mount Scale View

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