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Werkgroep Leidse Sterrewacht - Willem-Jan Trijssenaar

120-year-old telescope back after maintenence

After a period of maintenance, the 'Photographer' telescope is available once again for visits at the Old Observatory.

At the end of August last year, the Photographic Double Refractor's lenses were removed for maintenance. This was the first time in decades that this kind of maintenance was done on the lenses of the telescope. The maintenance project was carried out by Het Marinebedrijf, which also ensured the safe return and installation of the lenses on February 16th.

Initially the lenses would only be cleaned. During the disassembly, however, it became apparent that more maintenance was required. The Photographer's lenses consist of two separate lenses, which are attached to each other with a ring. This ring was completely worn out and had to be replaced. That's why the project took longer than initially expected.

It was well worth the wait. The following picture of the Orion nebula was made last week with the Photographer.

Orion nebula photographed with the Photographer. Photo by: K. Moddemeijer & W.J. Trijssenaar / Werkgroep Leidse Sterrewacht

Always in tip-top condition

Keeping the lenses or mirrors of your telescope clean is very important for doing astronomical research. With modern telescopes such as the GranTeCan in La Palma, a whole team of engineers is responsible for keeping the mirrors in tip-top condition. Not an easy task, since the mirror in the telescope consists of 36 individual segments that must be perfectly aligned.

Even with the historic telescopes in Leiden, keeping the lenses clean is not easy. The main lens of the Photographer, with it's 33 cm diameter, weighs more than 20 kilograms! It is already quite a challenge to remove the lenses safely without damaging them.

When the Leiden Observatory still used the Leiden telescopes for research, this type of maintenance was done more frequently than now. Because scientific observations are now made with telescopes abroad, the Leiden telescopes no longer have the highest priority. It is therefore exceptional that the maintenance has now taken place.

Back for visits

During guided tours, open days and other events, the Photographer can be visited by the public. During Wednesdays and weekends, visitors can take part in a free guided tour that also passes this telescope. Groups can book private tours, which are also available on evenings. If the sky is clear, it is possible to look through the telescope during a visit.. Check the website of the Old Observatory for the different ways to visit the observatory.

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