Altazimuth Pavilion

South Entrance, Altazimuth Pavilion

Tucked away in one corner of the Royal Observatory at Greenwich stands a sturdy but pleasing brick building which states its purpose above the door, Altazimuth.  Designed by a collaboration of the then Astronomer Royal, William Christie and William Crisp (architect of the Admiralty Department of Works) it was completed in 1896/9 and named after the type of telescope originally in the dome.  Over time it has survived being damaged in 1940 by the WW2 Blitz and shrapnel as well as a government minister's proposal to demolish it.

Its original purpose was to house instruments and measure two coordinates used to fix the position of a celestial body in the sky, the altitude (its position above the horizon) and the azimuth (its position east along the horizon) and it is from this coordination system it gets its name, Altazimuth (dictionary definition - a telescope that can swing horizontally and vertically).  Today it currently holds a photoheliographic telescope used for photographing the sun.

A later addition to the building in June 1910 was the weathervane which represents Halley's Comet. The moveable roof dome opening is turned by hand.  Most of the internal space is taken up by massive supporting columns intended for the main telescope but there is enough room on the ground floor for a small exhibition on the sun but the upper floor with historic instruments is only opened on specific occasions.   

The Altazimuth Pavilion's location is because it was the only site available to the Royal Observatory and is seen here from its north entrance, the flat circle behind left is the  planetarium and the dome beyond is the New Physical Observatory (known as the South Building) competed in 1899 by the same architect, (William Crisp), to house the Astronomer Royal, observatory staff, library, records and other paraphernalia for observing the heavens. Today the position of Astronomer Royal (which dates from 1675) is largely a honorarium one but it is still a prestigious title awarded to a renowned scientist working in the field of astronomy.

An entry to ABC Wednesday, a journey through the alphabet now starting its 15th  peregrination here