ADH  Baker – Schmidt Telescope

91 cm (36 inch)


Summary; History; Current; Technical; Sources; Links; Gallery:

In brief
Historical Background

  • The name of the telescope, ADH, reflects the names of different observatories that sponsored the telescope. A stands for Armagh Observatory, the main observatory in Northern Ireland; D for Dunsink Observatory, outside Dublin in Eire; and H for Harvard.
  • “Something must be said here about Armagh, in particular, because it comes very much into the story. Armagh Observatory – about  thirty miles inland from Belfast – was founded in the late 18th century and during Victorian times an important star catalogue  was compiled there by the then Director, a formidable gentleman named Romney Robinson. (Many stories are told about Dr Robinson.  It is certainly true that on one occasion he managed to make the  Government re-route a major railway line, on the grounds that  the vibration of passing trains would prove an intolerable nuisance to the astronomers at Armagh.) Subsequently things became rather difficult and the Observatory’s revival came only in the 1930s with the arrival of Dr Eric Mervyn Lindsay, who had studied  astrophysics under Shapley at Harvard. Lindsay had been assistant at Boyden before being called home to his native Ireland to take charge of the ailing Armagh Observatory where to be frank, very little research had been done for decades. Lindsay was nothing  if not energetic. He revitalised the Observatory whose main instrument had been a modest 10-inch refractor; he installed an 18-inch Schmidt telescope, able to photograph wide areas of the sky… His Boyden work with the Magellanic Clouds had shown him the importance of southern stations, and Boyden was an ideal site for a new  telescope of the kind needed for this sort of work. He joined forces with the Director of Dunsink Observatory, Professor Briick, and with Shapley, who was still at Harvard. Between them they raised sufficient funds for the construction of a new telescope, and in due course the ADH 36-inch was  installed.” [Copied from Moore, pp. 124 – 125.]
  • “The ADH 36-inch was installed. The optical system was of the Schmidt-Cassegrain pattern. The main drawback of a more conventional telescope is  its small field of view; to photograph the entire sky with, says  the famous Hale 200-inch at Palomar would take an impossibly long  time. A new system had been developed in the 1930s by Bernhard  Schmidt, an Estonian who had originally been concerned with  the manufacture of explosives, but had blown off one of his arms, and had turned to optics as being rather safer. Basically, his idea was to use a spherical mirror rather than a paraboloid, and to correct the inevitable faults by means of a highly complex plate at the top end of the tube. The result is that wide  areas can be photographed with good definition right to the edge of the plate, and Schmidt’s have proved invaluable – in fact,  they provide so much information that only’ recently have instruments been developed for analysing the results with reasonable speed.”  [Copied from Moore, p.125.]


 Consortium  from Ireland and the USA:

  • Armagh Observatory: North Ireland
  • Dunsink  Observatory: Republic of Ireland
  • Harvard  University: USA

Where  Located:

Current Information
Present  Location:
Boyden Observatory
University  of the Orange Free State


Technical Details
Type:Schmidt-Cassegrain type Reflector
Aperture: 36 inch (91.4 cm)
Focal Length: 119 inch (303 cm)
Operational History:


Link to the Main Bibliography Section and more information about Sources.

Pictorial  Sources:


  • Moore,  P. & Collins, P., Astronomy in Southern Africa, pp.124 -125.  (General Source)
  • Smits  P. A Brief History of Astronomy in Southern Africa. (Unpublished).
Related Internal Links:
Related External Links:
SAO/NASA Astrophysics Data System (ADS)
Armagh Observatory


The Baker Schmidt Telescope. The boy in the picture is Derck Smits – the son of past ASSA President Peter Smits – here as a six year old. Derck became Proffessor of Astronomy at Unisa. Source: A.S.S.A. Archives: Peter Smits Collection.