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Observatory Saltsjöbaden and its astrograph

A visit to Saltsjöbaden's Astrograph

  1. Introduction
  2. The excursion to Saltsjöbaden
  3. Historical background
  4. What is an astrograph?
  5. Optical performance
  6. Finder telescope
  7. Tracking and motor operation
  8. Object tracking, finder telescope
  9. The elevator
  10. The Dome
  11. Glass plates (film)
  12. What research was done with this astrograph?
  13. Who has worked on this astrograph?
  14. How it ended?

8: Object tracking, finder telescope

In the 1930s, there were no computers or electronic cameras, the speed of the motor was refined manually. It is precisely for this aforementioned finder telescope was used to. Kerstin Lodén told me that this astrograph were controlled entirely by hand.

To mention just some of what the astronomer had to put up with. The observations made in the dark, thus, in winter and at night. Local heating of the air providing atmospheric concern and thus blurred images, that means you do not have the observatory heated in the areas where the astrograph stands. In this cooled temperature the astronomer maybe had to sit one hour and stare in the finder telescope and precision control the drive's motor speed, constantly vigilant upcoming deviations.

To a help in this the finder telescope's there is a crosshair where you tried to keep a reference star centered. Professor Gösta Gahm at Stockholm Observatory have told me about observations on other instruments in the 1960s how he used an electric heated flight suit!

Observatory Saltsjöbaden and its astrograph

On top on the astrograph sits a finder telescope mounted.

It is at this upper telescope tube astronomer sat and peered in to precision control the electric R.A. motor manually and sometimes small Declination corrections. The astrograph must always be precisely targeted to a reference star, otherwise, blurred stars!

Observatory Saltsjöbaden and its astrograph

Here we see three of the counterweights to R.A. axis and a complex system of shafts and struts.

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