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

Content:

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?

12: What research was done with this astrograph?

Kerstin Lodén tells:

"One important area was to determine the position of various stars, it was used as a basis for statistical calculations. Measurement of light intensities and spectral properties was another important area. For the astrograph there was an important accessory, a prism. The prism was low refracting and covered the entire front lens, this could perhaps made up to a thousand parallel spectra taken of stars in a single exposure."

Kerstin Lodén tells:

"However, that usually it was more in hundreds of spectra at the observations made outside the Milky Way densest areas. With this accessories the astrograph became a spectrograph. Spectrogram of a star was a modern method in 1930 to determine which class the star belonged to."

In the basement we also found a wooden box with an exciting accessory. There was a heavy metal frame with metal wires stretched in, dimension was such that it seemed be mounted over the 40 cm lens. What function was neither I nor Nippe to figure out.

Kerstin Lodén says:

"The mysterious wooden box, I remember, on closer reflection. Perhaps it was already there with the delivery of the astrograph? To the best I know it has at least not been used."