The telescope

The Swedish 1-m Solar Telescope (SST) on the island of La Palma, Spain, had first light with a stopped down 60 cm aperture on March 2, 2002. On May 21, the telescope was opened to full aperture and the adaptive optics system was switched on for the first time.

The Swedish 1-m Solar Telescope (SST)

The Swedish 1-m Solar Telescope (SST). Photo: Göran Scharmer.

Already on the second day of operation the SST delivered diffraction-limited images, i.e., it reached the theoretical resolution limit for a telescope of this size. This means the SST has very small optical aberrations after compensation by the adaptive optics system, designed to counteract blurring caused by the atmosphere. This enables solar astronomers to see and photograph solar details of smaller size than previously possible.

About the telescope

The SST will address current and important questions concerning solar magnetic fields and the dynamics of the upper solar atmosphere and will also be used to improve our understanding of the formation of stellar spectra.

The front lens of the SST has a diameter of just under 1 meter, making it the second largest optical solar telescope in Europe and the third in the world, after the Goode Solar Telescope in Claifonia, USA.

Located on the best known site for solar telescopes in the world, the SST can see details as small as 70 km on the solar surface. This requires the use of a so-called adaptive mirror that corrects for the blurring caused by the Earth's atmosphere 1000 times per second. The SST is the first solar telescope that is designed for use with such a mirror.

The SST replaces a previous 50 cm telescope that has been a world leading solar research instrument for over ten years.

The SST is operated by the Institute for Solar Physics of the Royal Swedish Academy of Sciences but located within the Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias on the island of La Palma, Spain.

Royal Swedish Academy of Sciences

Observatorio del Roque de los Muchachos

Adaptive optics is the future of large telescopes. It is a new and exciting technique that is still developing quickly and has already demonstrated dramatic improvements of image quality on several large night-time telescopes around the world.

Adaptive optics

Modern solar telescopes are either vacuum telescopes, filled with helium, or use careful control of the optic's temperature to reduce heating of the air in the telescope. The SST is a vacuum telescope.

Learn more about how the SST is designed

Here are some drawings of the new telescope:

La Palma Tower (illustration).

Illustration by: Institute for Solar Physics

Solar telescope (drawing).

Blueprint by Klas Bjelksjö.

Many people have been involved in this project:

People involved in the project

Funding

The Royal Swedish Academy of Sciences quickly approved 5 million SEK for the project and thereby made it possible to raise additional funds. The remaining 12 million SEK that were needed came from The Knut and Alice Wallenberg Foundation, Marcus and Amalia Wallenberg's Memorial Fund, The Marianne and Marcus Wallenberg Foundation, the LEST foundation and the Institute for Theoretical Astrophysics in Oslo.

Observing with the SST

Dark room, colourful light from technical equipment..

Optics lab in basement during observations. Photo: Dan Kiselman.

Most of the SST observing time is used by observers from Sweden and Spain as well as from our partner institutes. There is also observing time available to observers from other institutes through purchase and various international agreements. Information can be found in our wiki.

SST wiki

Photos of the SST

Please be sure to include proper credit if using these photos of the SST with surroundings.

Photos of the SST with surroundings

Postal address in La Palma

Grupo Sueco del Observatorio del Roque de los Muchachos
Apartado 66
ES-38700 Santa Cruz de La Palma
Canarias
Spain

For further contact details, please visit our contact page: Contact

Last updated: 2025-10-16

Source: Institute for Solar Physics

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