Observatory Technology

Operating a remote observatory under dark skies represents one of the most exciting levels of this hobby for me. What fascinates me most is the seamless interaction between all technical components from the mount to the image acquisition. Below, I present the key components and solutions that make up the Gemsbock Observatory.

Observatory Hut

The structural foundation of the observatory was provided by Rooisand: a roll-off roof hut whose roof slides northward and seals tightly when closed, keeping out dust and sand. The telescope rests on a freestanding pier that is decoupled from the hut, effectively isolating the telescope from local vibrations.

The electrical setup includes a stable power supply with multiple EU sockets, as well as an internet connection as essential backbone of remote operation.

One aspect that deserves special mention is the familiar, reliable support structure at Rooisand: assistance with unexpected issues is always quick and dependable. This is an invaluable advantage when operating a distant observatory.

Instrumentation

telescope on pier

At the heart of the setup is a Planewave CDK14 mounted on a 10Micron GM2000HPS II mount, supported by a robust Baader steel pillar. The image train includes a Televue 0.8x reducer (successfully used for years on the CDK12.5 at the Chamäleon Observatory on Onjala) and a QHY 268M camera with a 7-slot filter wheel equipped with LRGB, Hα, OIII, and a long-pass yellow filter for observing exoplanet transits.

For flat-field calibration, a Baader flatfield panel mounted on the southern wall of the hut is used. Control hardware, power relays for the instruments, and a LAN switch are neatly integrated into a Baader OMS system, housed in a dustproof aluminum case beside the pillar. Accurate time synchronization is achieved using a Ublox GPS mouse.

gemsi

For visual monitoring from home, an Abus security camera is installed. A firewall secures the VPN connection, and the roof power supply can be safely disconnected via an IP power socket in case of thunderstorms.

Of course, no observatory would be complete without a mascot: „Gemsi“, the skull of an old female Gemsbok that once lived on Rooisand and now watches over the observatory in my absence and gave it its name. .

Control and Automation

Control is handled through a series of specialized software tools:

  • BktTimeSync for GPS-based time synchronization
  • Abus web interface for visual monitoring
  • VPN and remote desktop access (e.g., Google Remote Desktop)
  • Stellarium as a planetarium tool, with image fields pre-planned in CCDGuide and Aladin
  • NINA for imaging sequences, extended by custom Python scripts
  • PixInsight for stacking and post-processing

Custom Python scripts manage:

  • Power relays for the mount, camera, focuser, mirror fan, and flatfield panel
  • Roof opening and closing
  • Evaluation of Abus camera images to determine roof and mount positions
  • Status notifications sent directly to my smartphone via Pushover

Initially, I closed the roof manually, since the telescope extended above the roofline when unparked, a risk I wanted to avoid. Over time, this manual step became impractical, so I automated both mount parking and roof control, secured through visual feedback from the monitoring camera. A neural network now detects both roof position and mount status, ensuring safe opening and closing entirely without traditional limit switches as potential points of failure.
Today, even the startup sequence from powering the instruments, initializing the mount to opening the roof is fully automated. In most cases, a night’s observing session now involves just three steps:

  1. Check the weather conditions
  2. Start the NINA sequence (everything else runs automatically)
  3. Check via smartphone in the morning that the observatory closed safely

Finding Solutions for Every Challenge

Parking Position (Upside Down)

To minimize dust exposure, the telescope is parked upside down. Combined with a Spandex light cover, this effectively creates a closed tube without the need for a front cap.
At first, I planned to lower the telescope directly onto a cushion when parked. However, because the mount’s final movement occurs in declination and a complete "touchdown" would have required an additional movement in right ascension, this idea was set aside.
Now, the telescope parks just above the cushion, leaving only a very small air gap that keeps dust out reliably.

Dust Protection for the Camera

In its parked position, the camera faces straight upward, which allows fine quartz dust to enter through the ventilation slots. After testing various nylon mesh filters, an unexpected solution was found in the home-brewing market: a mash bag turned out to be a perfect dust filter. It slightly reduces cooling efficiency but provides a very good protection.

Securing the Spandex Cover

To ensure the Spandex cover stays in place even in windy conditions and does not sag into the optical path, a Velcro strap “cage” was installed alongside the carbon struts.
In addition, pairs of neodymium magnets hold the cover in place on the front ring. The inner magnets are fixed with superglue to eliminate any risk of falling onto the primary mirror.

Dust Protection for the Camera
Cage for the Spandex cover
Magnet Fixation on the Front RIng