Sydney Observatory is temporarily closed for maintenance works. Please sign up here to receive updates when we re-open mid-2022.
Discover the visible history of Sydney Observatory and view the impressive features that played significant roles in Sydney’s colonial history.
Fort Philip Rampart
Work on Fort Philip began in 1804 and was abandoned in 1806, after completing just three walls. The design of the fort was a hexagon with stone walls several metres thick. Rediscovered in 2008, the bombproof has curved sandstone faces that indicate that it would have had a domed roof.
Signal Station and Flagstaff
More than a century of shipping signals were sent and received using flags at the Sydney Observatory site.
Two flagpoles were used to pass messages to signal stations and port authorities between 1825 and the 1920s. Flags informed port authorities of the names, origin and cargo of new arrivals in Sydney Harbour. Weather and other information was communicated to ships in the harbour and neighbouring signal stations down the Parramatta River. In this way, messages could travel quickly throughout Sydney and mark the arrival of the post and other goods.
The sandstone Signal Master’s Cottage was erected in 1848 and extended several times to house the signal master, his family and his equipment. The current flagstaff was installed in June 2008 and was generously provided by the Bruce and Joy Reid Foundation.
The flags currently flown are:
- the Australian flag
- the New South Wales flag
- the Australian Aboriginal flag
- the Torres Strait Islander flag
- constellations visible during night sessions
- planets visible in the night sky
- phases of the Moon
- maximum expected temperature for Sydney (three flags)
- astronomical events including equinoxes, solstices, meteor showers and eclipses
- various shipping signals
Before the Observatory was built, Sydney didn’t have an accurate time standard. The Observatory’s first function was to calculate the correct time from the movement of the stars. The Time Ball signaled the time to ships and the post office in Martin Place at 1pm each day, accompanied by a cannon blast, providing an audio and visual notification.
Read more about the Time Ball and its history in the MAAS online collection.
Sydney Observatory’s first ‘weather forecast’ was issued in 1858 by the first Government Astronomer William Scott. Weather records have been collected from Observatory Hill, between the grounds of the Observatory and Fort Street School site, since this time, thereby creating a continuous and comprehensive record of Sydney’s temperature, humidity and rainfall. The contemporary weather station is managed by the Bureau of Meteorology.
The Sydney meridian is a line passing through the Observatory’s Transit Circle Telescope running north-south. The historic stone pyramid that stands in front of the Observatory is a survey marker, or trig station, on the Sydney meridian. This stone marker with its highly accurate position would have been essential for 19th century surveyors to use in surveys of Sydney – ensuring that property boundaries and sewage lines were accurate. Today, a new trigonometrical survey marker, Trig E, is placed on top of the Time Ball Tower.