Flux (light) Collector (later called The Dutch Telescope)

90 cm (36 inch)

Index:

Summary; History; Current; Technical; Sources; Links; Gallery:

In brief

Important Contributions:

The Flux Collector was used to observe and analyze a wide range of stellar surface qualities in the Milky Way and Magellanic clouds. The considerable database of photometry of thousands of stars was valuable input to the Hipparcos satellite programme of the European Space Agency (ESA), and it is still used in combination with the GAIA satellite data. (Pel, 2023)

Description:

The telescope was the first fully automated telescope in South Africa. It combined three unique innovations.
• Fast and accurate electronic preset pointing (“go to” pointing) with a slewing speed of 90o per minute and an accuracy of 15 arcseconds.
• High resolution over a small field of view (hence the name “light collector”). This uses a 91cm primary aperture with an a-spherical primary mirror and a spherical secondary, manufactured by Pearson at Yerkes Observatory, USA.
• Directly integrated 5-colour spectrophotometer with ultra-stable filter passbands in the visual and near ultraviolet part of the spectrum.
The motor assembly, control panel, and electronics were made at Leiden University. The spectrometer was developed by Theodor Walraven and UV-transmitting materials were manufactured mostly by Johanna Walraven. (Pel 2023)

Historical Background

Owners:
Leiden Observatory.

Where Located:

Leiden Southern Station, Hartebeespoort: 1957 – 1978.
European Southern Observatory (ESO) at La Silla, Chile: 1979 – 1997

Current Information

Present Location:

Owner: Leiden University Observatory.

Status: Decommissioned.

Condition:

Technical Details

Type: Dall-Kirkham Cassegrain Reflector
Aperture: 36 inch (91.4 cm)
Focal Length:
Mirror:
Mounting:
Attachments: Fitted with a simultaneous operating five colour spectrometer.

Manufacturer:

• Mirrors and optics: Pearson of Yerkes Observatory, USA.
• Mechanical structure: Rademakers, Rotterdam, Netherlands.
• Motor assembly and control: Leiden University, Netherlands.

Operational History:
Building:
1957-1978: Leiden University Observatory Southern Station, Hartbeespoort
1979-1997: Joint operation Leiden University Observatory and ESO La Silla, Chile.

Sources

Documentation:

Pictorial Sources:

Pel, J.W. Pers. comm. 2023.
Moore, P. & Collins, P., Astronomy in Southern Africa, p.110.

Bibliography:

Moore, P. & Collins, P., Astronomy in Southern Africa, pp.108 – 109. (General)
Pel, J.W., “The ‘Lightcollector’ telescope of the Leiden Southern Station and Walraven’s Spectrophotometer. Unpublished, 2023.

Acknowledgement:
Many thanks to Jane and Vincent Carruthers who helped to research and write this page.