Building a private observatory is more than a construction project – it is the realization of a long–held dream. On the rooftop of my home in Hart bei Graz, Austria, I have begun the design phase for the installation of a 2.7-meter Pulsar dome, creating a dedicated space for remote astrophotography.

The unique location on the main roof required careful planning, from structural preparations and access solutions to the integration of power, networking, and climate control. What began as an idea has now taken shape step by step.

Design Project & Official Permission

Prior to the installation of the observatory dome, the project required formal approval by the municipal building authority. Given that the structure was to be erected on the main roof of a residential building, its impact on both the structural integrity of the house and the surrounding environment had to be assessed. From the outset, it was important for me to clarify that the observatory would not affect the privacy of the surrounding neighborhood. Due to the height of the dome and the geometry of the shutter opening, no direct view from the telescope into adjacent properties is possible. The optical axis only gains an unobstructed view of the sky from an altitude of approximately 20° upwards, ensuring that the observatory exclusively serves astronomical purposes and is remotely operated from inside the house.

For this purpose, architectural drawings and a project description were prepared and submitted to the municipality. The project was then reviewed by the municipality’s building expert, who confirmed its conformity with the relevant regulations. Following this expert assessment, the observatory was officially approved. This approval ensured that the observatory meets all legal requirements and provided a solid framework for the subsequent construction works.

Access to the Observatory

Access to the observatory is provided from the upper terrace of the house via a specially constructed spiral staircase. This solution ensures a compact footprint while offering safe and direct entry into the dome. The staircase integrates harmoniously with the overall architecture of the building and is designed primarily for maintenance purposes. Since the observatory is operated remotely under normal conditions, physical access to the dome is required only in exceptional cases such as inspections, servicing, or technical adjustments. This arrangement minimizes interference with the residential areas of the house while maintaining full operational independence of the observatory.

The 2.7m Pulsar Dome

The observatory dome was acquired via the platform willhaben, where a new unit from an astronomical association was offered for sale at a special price. My wife Natascha encouraged me to purchase the dome, a possibility I had not seriously considered until then 🙂

The contact with the association’s chairman, a teacher at the Higher Technical Institute (HTL) in Wiener Neustadt and of course an astro-enthusiast too, was both pleasant and professional, and arrangements were made for collection at the beginning of August.

The dome is a Pulsar 2.7-meter model in the high-profile version, Gen 1, manufactured in reinforced-fiberglass (GFK) for durability and weather resistance. Its functionality includes a motorized shutter system for opening and closing the observing slit as well as full dome rotation driven by dedicated motors, allowing the telescope to maintain an unobstructed view of the sky during tracking. This combination of robust construction and reliable mechanics makes the dome well suited for long-term astronomical use under Central European conditions

Geometry inside …

The planning of the interior setup greatly benefited from the expertise of my wife, an interior architect skilled with 3D-design software (SketchUp). She carefully analyzed the geometry of the dome and the available space to determine the optimal arrangement of the optical equipment. Particular attention was given to the necessary height of the telescope pier, ensuring both to accommodate the full range of motion of the mount and make maximum use of the dome’s observing slit.

A key factor in assessing the required pier height was ultimately the geometry of the mount with its right ascension axis tilted by 90°. In this position, the minimum altitude was used as the critical reference for evaluating both the observable sky through the dome shutter and the clearance between the telescope tube and the dome structure. This analysis ensured that the instrument could move freely without risk of collision. The evaluation was carried out using the 10-inch carbon Newtonian telescope, including its 30 cm dew shield, as shown in the accompanying sketches out of SketchUp.

Upcoming article: Part II – Cutting the Flat roof Sealing 🙈… the Installation of the foundation directly connected to the reinforced top ceiling