The Observatory

Nightsky Observatory was build for two purposes:
Offering visitors  the opportunity to have a look to various celestial objects – the moon, the planets and some of the prettiest deep-sky objects on the northern hemisphere. With a small telescope special for solar observation, visitors also can look at prominances and other details on our sun during daylight.
Second is to make pictures of deep-sky objects to reveal the beauty of our universe and make visible, what can’t be shown just by looking through a telescope with naked eye. Some of these pictures will be  exhibited at the gallery.

The Observatory, Aug, 2023

The Building

It has been a long way to find a proper location for the planned observatory, but finally in the springtime of 2022 it could be fixed on the grounds of the Astronomical Center Martinsberg (AZM) in the municipality of Martinsberg in the southern Waldviertel. The AZM is located in one of the darkest regions outside of the Austrian Alps. It was built in 2021 on the site of the historic “Orion” observatory and offers a lecture and exhibition building with the associated infrastructure. This made it possible to supply the Nightsky Observatory with electricity without any problems. The AZM is operated by the municipality of Martinsberg in cooperation with the association “AZM/Observatory Orion”, which offers public tours and lectures.

The observatory was designed to fit the dimensions of a 10-foot dome and was constructed as a single-row solid brick rotunda. The building is settled on a 30 cm thick reinforced concrete foundation.
The 30 cm thick and 2.4 m high telescopic pillar, also made of reinforced concrete, was decoupled from the foundation and got its own 50 cm diameter and 90 cm deep foundation. A local construction company was commissioned to carry out the necessary excavation workings and to manufacture the foundation and concrete pillar. In order to ensure the required tolerance of +/- 4 mm for levelling the dome, the masonry was finished with a concrete collar, which also adds more stability to the building. The wall and the concrete ring was made by me manually.

The building can be entered via an east-facing door. To get access to the telescope more easily, a ceiling was installed 1 m above ground level.

Data of the Observatory

Geographical location: 15°07’23”23 East
48°22’53”60 North
864 m above sea level
Diameter: 302 cm
Overall height: 405 cm

Diameter: 305 cm
Height of dome segments: 153 cm
Overall height with base ring: 184 cm
Dome gap width: 92 cm
Manufacturer:Technical Innovations, FL, USA



Main Instrument is a 12 inch Newton-Telescope manufactured by the Austrian company ASA. It has a focal length of 1086 mm and a focal ration of f 1:3,6.  The tube is made of carbon fiber composite and is therefore almost insensitiv to temperature fluctuations. The telescope is optimized for photographic purposes.  It got a large secondary mirror for fully illuminated large sensors.Therefor a 3-inch corrector für image flattening is used in a motorized 3 inch Crayford focuser. Focusing is controlled by Computer-Software. If necessary, the corrector can be exchanged by a Barlow lens. The Barlow extends the focal length to 2060 mm, f 1:6,8.

The 12inch Newton beneth the opened dome

Moving the telescope is done by a direct driven mount DDM85 from ASA (AstroSystemeAustria). It is a gearless model with high torque motors instead of classic worm-gears. Its axes with a diameter of 85 mm carry a payload of 65 kg instrumental weight. The mount achieves a positioning accuracy of a few arc minutes over both hemispheres and a tracking accuracy of less than one arc second without guiding.This high accuracy is possible by using high-resolution encoders on both axes in conjunction with a complex pointing model.

In addition to the main instrument, there are some mobile telescopes primarily used for observing the sun in narrow-band and for demonstration purposes. Losmandy G-11 and GM-8 mounts are used for this mobile scopes.

Telescope Type Aperature Focal Lenght Focal Ratio Purposes
300 mm
1086 mm / 2060 mm
f 3,6 / f 6,8
Deep-Sky Photography
Meade SCT 12
300 mm
3000 mm
f 10
Visual, Moon, Planets
Vixen SD130SS
130 mm
860 mm
f 6,7
Visual, Sun, Moon
Pentax 75SD-HF
75 mm
500 mm
f 6,7
Widefield Photography
Lunt LS60/1200
60 mm
500 mm
f 8,2
Visuall, Sun at H-alpha

A monochrome CCD camera from Atik and onother from SBIG are available for imaging. Both cameras are equipped with filter wheels for RGB and narrow band filters. Therefore imaging can be done in color and in OIII, H-alpha and SII ranges.

For planetary imaging some Webcams are used as well.

Camera Sensor / Type Resolution Pixelsize Dimension Efficiency [peak / 656 nm]
Atik 16200 Mono
CCD KAF16200 Fullframe
4500 x 3600 pxl
6 µm
27 x 21,6 mm
56 % / 48 %
SBIG ST8300 Mono
CCD KAF8300 Fullframe
3352 x 2532 pxl
5,4 µm
18,1 x 13,7 mm
54 % / 38 %

Controlling and Software

Unlike conventional telescopes, the main telescope of the observatory on its mount only can be operated using a specific control softwarerunning on a connected PC. The programs Autoslew for the telescope control and ACC (ASA Control Center) for other components (focuser, rotator and cover) are connected to the software Maxim DL for image aquisition. Maxim DL is used to control the camera and the filter wheels, and it allows direct control to all telescope components as well as controlling the dome by linking the software Digital Domeworks. The software Sequence provided by ASA in conjunction with the planetarium programm Cart du Ciel is used for automated recording processes.

Maxim DL is used also for raw data acquisition as for data reduction. Final image processing is done with Photoshop.