Observatories that I have visited:
Stockholm's "new" Observatory, Sweden

Content:

• 1: Stockholm's Observatory, Historical background
• 2.1: Stockholm's Observatory, the Main building double refractor
• 2.2: Stockholm's Observatory, the Main building guided tour 2022
• 3.1: Stockholm's Observatory, the Newton reflector
• 3.2: Stockholm's Observatory, the Newton reflector guided tour 2022
• 4: Stockholm's Observatory, the Astrograph
• 5: Stockholm's Observatory, the Meridian observatory
• 6: Stockholm's Observatory, the Schmidt telescope

6: the Schmidt telescope

Now is only one building left to visit, the Schmidt telescope building.

A sign direct us to the Schmidt telescope observatory, it's the building you see through the trees.

A Schmidt telescope has a construction of one mirror and one correction lens, it's a compound design. This telescope has a mirror with a diameter of 1 meter but the opening is limited by the the corrector lens' 0.65 meter. There are not many of this kind of telescopes of this size out in the world. This telescope is not used for visual observations, only used as a camera, a Schmidt camera.

More to read about a Schmidt camera:

• https://en.wikipedia.org/ wiki/ Schmidt camera (Schmidt camera, Wikipedia)

The Kepler telescope up in the space that hunt for Exoplanets has a similar design and the Mount Palomar observatory has one. More to read about the Kepler telescope:

• https://en.wikipedia.org/ wiki/ Kepler space telescope (Kepler space telescope, Wikipedia)

This telescope was installed much later, in 1965. It replaced the old astrograph. This telescope has an effective opening of 0.65 meter compared to the old astrographs' 0.4 meter. The focal length is 3 meter compare to 2 meter of the old astrograph. F/4.6 and the old f/5, better sensitively and I think of much higher quality and less vignetting. But it must have been a mistake to place the Schmidt telescope at this place, the light pollution already at that time was heavy and they could never use this telescope as it would have been used.

At late 1960s they started to drawings planes how to build a new observatory at La Palma at the Canary islands in Spain, much less light pollution. It got the name NOT, Northern Optical Telescope, a cooperation between the Scandinavia countries. I visited that place in 1997, read here, La Palma observatory. I just wonder, was it no planes to move this Schmidt telescope to La Palma ? It's a very competitive telescope but maybe too expensive to move. It need a new control system and a corrector to get a flat focus plane, the original photographic plates were curved.

Some accident got it broken in the 1970s and it have never been used after that. Some funny thing, the computer that control the telescope is developed by SAAB. It was of the same type as the computer in the Swedish fighter aircraft Viggen.

This observatory is very compact, the Schmidt telescope is of the same size as the Newton telescope. The building is not wider, but much lower.

The telescope was out of order. Maybe it will be used as a conference room in the future.

Lot of tricks to have the dome water tight.

We have now visited all the observatories of Stockholm's Observatory at Saltsjöbaden and now heading home. Maybe I can get some photos of the Double refractor, the Newton reflector and the Schmidt camera in the future, they are all impressive to look at.

Astronomy is still my big interest in life. Stockholm's Observatory was my paradise in the 1990s and still is. Great thanks to all teachers who gave me all the exiting education about astrophysics.

The END