Figure 1: Go ogle image of Ro y al Observ atory . The - PDF document

Figure 1: Go ogle image of Ro y al Observ atory . The H-shap ed main building w as completed in 1828. The R o y al Obser v a tor y, Cape of Good Hope, a V aluable Cul tural Pr oper ty Prepared b y I.S. Glass South Afric an Astr onomic al Observatory, PO Box 9, Observatory 7935, South Afric a isg@saao.ac.za 1 Geographical p osition The Ro y al Observ atory , Cap e of Go o d Hop e is the original name for the headquarters of the presen t-da y South African Astronomical Observ atory . It is situated in the suburb of Observ atory , a part of Cap e T o wn, W estern Cap e Pro vince, Republic of South Africa. The en tire prop ert y of 9 hectares o ccupies a small hill 3 km east of cen tral Cap e T o wn, within the Tw o Riv ers Urban P ark . The lo cation w as c hosen to b e within view of the Cit y's harb our to p ermit the visual signalling of time to visiting ships. The prop ert y is one of the last remaining places close to the cit y cen tre where the original ecology of the area is preserv ed. 2 Longitude and Latitude � 0 00 The Observ atory is situated at longitude 01h 13m 54s.6 E; latitude 33 56 03 .5 S; elev ation 15m. This is the precise place o ccupied b y the Airy T ransit Circle, up on whic h all South African geographical p ositions w ere formerly based. 3 General description and w orld cultural imp ortance The Ro y al Observ atory , Cap e of Go o d Hop e, w as created on 20 Octob er 1820 b y an Order of King George IV of the United Kingdom, a colon y of whic h the Cap e then w as. The �rst building w as completed in 1828. F or most of its existence it w as the ma jor con tributor to p ositional astronom y in the southern hemisphere. Among its most notew orth y ac hiev emen ts are: the �rst successful measuremen ts of the distance of a star (Alpha Cen tauri) b y Thomas Henderson (1832-3) and the �rst use of photograph y to mak e a systematic sky surv ey (Gill, 1885 on). Gill w as one of the leaders of the Astrophotographic Congress, the precursor of the In ternational Astronomical Union. 1

4 P artial in v en tory of extan t items 4.1 Buildings � The main building of the Observ atory (see Fig. 1) w as completed in 1828. The cen tral part comprised observing c ham b ers for a transit telescop e and a m ural circle as w ell as an en trance hall and t w o small computing ro oms. The w est wing comprised quarters for the Astronomer and the east for t w o assistan ts. It w as designed b y the noted na v al arc hitect John Rennie, Chief Engineer to the Admiralt y . � Other early structures include the south meridian mark for the m ural circle (ca 1828) and a dome running on cannon balls dating from 1849 (for the 7-inc h Merz telescop e). � The 18-inc h dome (former heliometer observ atory), 1888. � The McClean (Victoria) dome of 1897; an early w ork b y the in ternationally famous arc hitect Herb ert Bak er. 4.2 Some mo v able artefacts surviving � A rep eating transit b y Dollond, describ ed in a publication of 1820. (used b y the �rst astronomer b efore the completion of the main building). � 7-inc h telescop e b y Merz (1849). Used for T ransit of V en us 1882. Used also b y R T A Innes, the disco v erer of Pro xima Cen, for double star w ork. � A sp eculum mirror b y W Hersc hel (1811). � Time signal pistol 1833. � Regulator clo c ks b y Molyneux, Hardy , Den t and Rie�er. The Hardy clo c k, whic h dates from the 1820s or sligh tly earlier, w as in the T ransit Ro om and w as used b y Henderson in his Alpha Cen w ork; the Molyneux clo c ks (one eac h sidereal and mean) date from a similar time. � Ross lens used b y Gill for his ep o c h-making photograph y of Great Comet of 1882 � Large Dallmey er p ortrait lens used for Cap e Photographic Durc hm usterung { the �rst photographic sky surv ey � Ey epiece and lens of Airy T ransit circle (installed 1854). � \Kew P attern" Heliograph b y Dallmey er (1878). � 6-inc h Grubb telescop e (1882). � Astrographic telescop e (Grubb, 1889). � McClean (Victoria) telescop e (Grubb, 1897). � Gill transit circle (1905), the precursor of all mo dern transit circles. � 18-inc h telescop e (1955) on Heliometer moun t b y Repsold (1885). In addition, the library , whic h is the National Library of Astronom y , is one of the most comprehensiv e astronomical libraries in the w orld, b oth for an tique and con temp orary material. 5 Brief surv ey of the history of the site and its uses In pre-colonial times the prop ert y w as probably used for grazing b y the indigenous San pastoralists. Later, but b efore it w as acquired for the Observ atory , the area w as farmland, though ro c ky , treeless and windsw ept. It nev ertheless supp orted a remark able v ariet y of seasonal grasses and bulbs. It is underlaid b y greyw ac k e, quartzitic limestone and shale. Although it is the habitat of man y in teresting �ora and fauna, it is particularly noted for b eing the last remaining natural habitat of a rare Iris Mor ae a aristata and the northern limit of the W estern Leopard T oad Bufo p antherinus , an endangered sp ecies. F rom c a 1820 the prop ert y has b een in use as an observ atory . In 1971, it b ecame part of the South African Astronomical Observ atory . No longer barren, o v er the nearly t w o cen turies of its existence the site has b een plan ted extensiv ely with shrubs and trees to act as windbreaks. 2