Other Associations


The WLS or ‘Werkgroep Leidse Sterrewacht’ is a group of enthusiastic (amateur)astronomers who share their love for telescopes, astrophotography and the universe. The organisation was founded in 1982 with the goal to maintain the telescopes of the Old Observatory in Leiden. Nowadays, they focus on these telescopes but they also organise public activities like the Avondje Sterrewacht, where you can visit the observatory and observe with the telescopes. Moreover, they help out at big events like the open day and the annual museumnacht.

The WLS and Kaiser are working together to improve the telescope trainings given at the observatory and help each other out at events. A lot of members of Kaiser are also members of the WLS. The board of the WLS consist of Frans van Beek, Casper Elshof, Jan Feiken, Willem-Jan Trijssenaar and Theo Klaver. If you want to know more about them, visit their website.


The Vo-S or ‘Vereniging Oude Sterrewachters’ was founded on the 2nd of December 1998 with the goal to connect everyone who has links to the Observatory in Leiden. Everyone who has been involved with the Observatory can become a member.

The chair of the board is Niels van Weeren and together with his secretary Maaike Damen and his treasurer Gerben Zwart they manage the association.

We organise activties together like the yearly mentor lunch in which the students of Kaiser can connect with the alumni of the Vo-S and we are planning on organising more.

More information about the Vo-S can be found on their website.


The JWG or ‘Jeugd Sterrenkunde Werkgroep’ is an organisation for children from the age of 8 who enjoy astronomy. Once a month, they meet at the observatory where their volunteers explain difficult astronomy-related subjects to their members.

Kaiser and the JWG work together at public events like the open day and Kaiser-Kapteyn day which was organised in 2022 for the City of Science.

If you know someone who wants to become a member, or if you want to help out at their activities you can find more information on their website.


The LWSK or ‘Leidse Weer- en Sterrekundige Kring’ is an association for (amateur) astronomers who are interested in the beginning and evolution of the universe, the characteristics and diversity of celestial bodies and the weather and climate on Earth.

They organise lectures and workshops for their members and offer the opportunity to further investigate interesting topics in small groups. The members also help each other with observing and handling their telescopes. For more information you can go to their website.