ASSA Johannesburg Centre

About Us

The ASSA Johannesburg Centre is a non-profit voluntary organisation for astronomers – professional, amateur, and absolute beginner.

Based in the Johannesburg Observatory, in Observatory, the society holds monthly meetings that feature a variety of guest speakers. These range from introductory workshops on how to use a telescope, all the way up to discussions on black holes and spherical trigonometry.

The society has access to 3 large telescopes:
A 26 inch Refractor Telescope, named after Robert Innes
A 12.5 inch Dobsonian Telescope, built by renowned South African astronomer, Cornelius Jacobs
A Telescope mounted with a 12 inch Tinsley Cassegrain, as well as a 6/7” twin refractor, built by the CSIR and donated by Christos Papadopoulos.

Meetings are held every 2nd Wednesday of the month, 19:30, at the observatory and online. If loadshedding permits, a star gazing session is sometimes held afterwards using the large 26″ refractor telescope, the Innes Telescope.

The centre also provides members access to the library which has some beautiful books and historical records dating back to the 1930’s.

Membership Fees

R275 pa for adults
R150 pa for Students and Pensioners
R50 admin fee for new joiners
R50 courier fee for Skyguide (if not collecting in person).
Membership to the society includes a free skyguide as well as newsletters to members-only star gazing events and excursions.


The Johannesburg Astronomical Association was founded in 1916, with RTA Innes as the first president and when it was amalgamated in with the Cape Association to become the Astronomical society of Southern Africa, he continued to serve as the president until 1923.

The 26 1/2” (673mm) Innes Telescope, designed especially for double star observing, was commissioned in 1909 and lens finally arrived and was installed in 1925. In the second half of 1925 it discovered 303 new double stars and 887 pairs were measured. The Innes Telescope is attributed with the discovery 6555 double stars and 579 asteroids or minor planets (The greatest number of discoveries of any terrestrial telescope). Many of the discoverers were members of ASSA Johannesburg. This telescope is still in use and used during Star Parties held at the Observatory by ASSA Johannesburg. It has been a fundamental in the observational operations of ASSA JHB and influenced the relationships between ASSA JHB and the landlords. ASSA JHB continues to be involved in care and maintenance.

In 1915 Innes discovered Proxima Centuri using a blink comparator to examine photographic plate of an area around Alpha Centauri (1910 and 1915). This is the nearest known star to the Sun, located 4.2465 light years away.