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Stefan Benz

GM 3000 HPS – Stefan Benz

The shock among the approximately 500 members and two dozen active volunteers of the association "Schwäbische Sternwarte e.V." was great when they were surprised by the news in the fall of 2015 that a nighttime fire had struck the Stuttgart Observatory. The lecture room had been completely destroyed, and the library inside was also a victim of the flames. The dome of the observatory including the historical Zeiss refractor, which is more than 100 years old, was not directly affected by the fire, but soot and smoke gas had caused such damage that extensive restoration measures were unavoidable.

Observation and celestial guidance were out of the question for the next two years. Instead, deconstruction, general renovation and reconstruction determined the everyday life in the association. The historical telescope was dismantled and brought to Jena to be disassembled, cleaned and repaired by the special company -4H- Jena engineering GmbH.

The two other telescopes of the observatory, which are permanently installed on the observation terrace, were fortunately not affected by the fire. These are a 16-inch Newtonian telescope and a 7" Starfire refractor. However, the mount was getting on in years. In addition, its electronic control did not allow automatic positioning, which could be quite annoying especially during star tours with large groups of visitors. So the purchase of a new mount was planned for a long time. The forced break of the observatory offered now a favorable opportunity for the exchange.

After intensive research the choice fell on a 10micron GM3000HPS- Mount, which should carry parallel to the 7" Starfire refractor a 4" Zeiss refractor with Hα-adaption from Coronado and a 4" wide field refractor from LZOS.


Montage und Aufstellort

The installation site posed a special challenge. The new mount was to replace the old one at the same location. However, this is not a classic dome with a lot of free space inside for a telescope, but a free-standing concrete column around which even larger groups of visitors can gather. A mobile stainless steel shelter protects the parked telescope from the elements. The tight dimensions of this hut were the problem: they made extremely elaborate, precise and detailed planning of the positioning of all devices on the mount necessary.

Therefore, the excitement was great when the new mount was delivered in spring 2017. Would everything fit or would there be nasty surprises? Fortunately, everything went well: The care used for planning paid off, the new mount with all telescopes fit into the canopy right away. The commissioning as well as the alignment of the mount was very easy and was done on the same day.

The team of Baader Planetarium deserves praise and thanks for the very good support and advice in the run-up and during the installation. In addition, Mr. Risch is to be thanked for his friendly support in troubleshooting when the mount had minor problems with the power supply in the first summer.

Since then, the mount has been running flawlessly in daily guiding operation; by now, well over a thousand visitors have observed the sky with its support. The operation with the outstandingly precise "GoTo" is a real delight, as it makes moving to the next object a breeze. No more sweating when you are standing in front of a group of inquisitive visitors and can't find the next object right away due to the light-infested Stuttgart sky.

The mount is also regularly used for photographic applications. A separate autoguider is not necessary. So even astrophotography from Stuttgart is possible, as this image of M42 shows. 17 exposures of 2 minutes duration each were added up.

Best regards,
Stefan Benz

Observatory Stuttgart


(translated Team Baader Planetarium)