Armagh Observatory hosts several heritage telescopes that have remained in their original setting since the days they were used for frontline science in the 18th and 19th centuries.
Six generations of telescope design are evident from the Kinge George III telescopes of 1769, the Troughton Equatorial, the Transit & Mural instruments plus the Grubb 15-inch reflector, Grubb 10-inch equatorial refractor, Calver Telescope of the 19th century and the Armagh Robotic Telescope from the modern era.
King George III Short Telescope
This telescope was made by James and Thomas Short. It featured a 6-inch mirror and of 2-foot focal length and was used by King George III at Kew Observatory to observe the 1769 transit of Venus. The telescope was part of the 1841 donation by Queen Victoria to the Armagh Observatory, which was negotiated by Sir James South. The telescope consists of a brass tube supported on a brass pillar and tripod, with interchangeable eyepieces, surmounted by a smaller finder telescope. There is a focusing mechanism on the side of the tube and the angle of the telescope can be altered with the adjustable arm fixed to the pillar base and eye-end. The accessories include a solar filter and additional optics which are adaptable to Newtonian, Cassegrain and Gregorian systems.
Troughton Equatorial Refractor
The 1795 Troughton Equatorial Telescope is the oldest in the world that remains in essentially its original setting in a rotating dome that was designed by Francis Johnson.
It was commissioned on the recommendation of Astronomer Royal Nevil Maskelyne as part of the initial instrument suite for the Armagh Observatory founded by Archbishop Richard Robinson, Primate of Ireland. The design was contemporaneous with Jesse Ramsden’s famous equatorial instrument, the Shuckburgh Equatorial.
Built by the Troughton brothers (Edward and John) in London, initially designed in 1789. A 2.75-inch refractor, one of the very first equatorial telescopes ever built, placed on a pillar of Armagh marble to separate it from the Observatory building. The telescope includes divided declination and equatorial circles, which can be rotated by hand, and four microscopes for reading the scale. The telescope was installed in December 1795 and remained in the dome until it was briefly removed for restoration in 1986.
Jones Transit Instrument
Built by Thomas Jones and installed in 1827, it was funded by Archbishop Beresford. Aperture of 3.75 inches, focal length of 63 inches and axis of length 30 inches. It is mounted on two stone pillars and in conjunction with a wooden reversing mount from the King George III collection.
Used to time the passage of stars across the meridian in order to determine their Right Ascension. It replaced an earlier instrument that had been built by a local clock maker named Alexander Waugh.
Measurements made by Thomas Romney Robinson (and others) were used to compile “Places of 5,345 Stars” in 1859 that established the scientific reputation of the Observatory and was regarded as one of the finest star catalogues of its day.
Three of the original Meridian Markers used to align the telescope (and the Mural Circle) at the start of each night’s observing still exist. Two are 2 km to the north in Tullyard and one to the south in Ballyheridan, just beyond the Armagh Golf course.
Jones Mural Circle
The Jones Mural circle was used with the Jones Transit Instrument to measure the declination of stars as they crossed the meridian.
It was installed in 1831, placed on a wall made of Armagh Marble, though Thomas Jones was summoned to Armagh to re-divide the circle as it was found to be unsatisfactory.
It underwent a series of modifications throughout the 1800’s. Today it has a 7.5-inch refractor by Thomas Grubb, the original lens was a 3.8 inch, with 56 inch circle. In addition, it had eight new microscopes added to read the circle, to confirm the exact measurement, and each microscope included a speculum mirror to reflect dim candlelight on the circle to ease reading.
Shown here with a model of Romney Robinson, the 3rd Director of the Observatory.
Grubb 15-inch Reflector
Built in 1835 by Thomas Grubb of Dublin, a 15-inch reflector that pioneered the design of clock-driven equatorial telescopes plus concept of levers to support and distribute evenly the weight of the mirror. It was the first clock-driven equatorial reflector, and following from the Great Dorpat Refractor in Tartu Observatory in Estonia built by Fraunhofer in 1824. The system of leaf springs on which the mirror rests was influential on the design of the large 72-inch reflector at Birr Castle a decade later. Placed in the 1827 Dome built by the benefaction of Archbishop Beresford. It is the second commercial Grubb telescope built (the first was at Markree Observatory in Sligo), and the oldest surviving one.
Grubb 10-inch Refractor
Built in 1885 by Howard Grubb of Dublin to be housed in the Robinson Memorial Dome, erected to commemorate Romney Robinson by his successor Dr Dreyer. It is a 10-inch refracting ‘Standard Equatorial Telescope’ and features a clock-drive with mechanical governor mechanism used by Dreyer to complete the classification of stars and nebulae for the New General Catalogue, published in 1888, initially with 7,840 entries. The dome can be easily moved by hand using pulleys and was also supplied by the Grubb Telescope Company. Represents the zenith of telescope and dome design prior to the introduction of electricity into astronomical observatories.
Calver 18.25-inch Reflector
The Calver Telescope, an 18.25-inch reflector built by George Calver (1882) and presented to Armagh Observatory in 1918 by Rev. William F.A. Ellison on his appointment as its 6th Director. The Calver Telescope was at this time the largest on the Island of Ireland, and featured a weight driven clock-drive. In 1950 it was converted to a Schmidt astrographic camera and an electrical drive motor added. The instrument was used in conjunction with the 10-Inch Grubb for extended study of binary systems until the 1980’s.
Ellison Reflector
The telescope is a 6.25-inch reflector that featured in Armagh’s 6th Director, the Rev. William Ellison, famous book The Amateur’s Telescope (1920). This was adapted from a series of articles he published in 1918 in The English Mechanic. Inspired the building of telescopes by amateurs in the USA, so pioneering and popularising amateur astronomy around the world.
The telescope is one of the smallest sizes that Ellison offered for public sale. This began in the early 1900’s with a price of £3.10s (about £450 today). This was for just for the mirror; the tube, stand and eyepieces would all have to be sought out, or made by the buyer.
Restored by Keith Venables and donated to Armagh Observatory in 2024.
Armagh Robotic Telescope
The Armagh Robotic Telescope, used for undergraduate student projects in Armagh today.
Recognising that the equivalent of 120 clear nights per year could be available to an autonomous robotic telescope situated at the Armagh Observatory and Planetarium, it was decided to construct a modern telescope and dome with the goal of making research quality observations of variable stars and other transient phenomena from the Observatory site in Armagh.
The telescope is a PlaneWave Instruments 43 cm f/6.8 corrected Dall-Kirkham Reflector with Carbon-Fibre Truss.
The dome is situated about 10 m south of the Robinson Memorial Dome. Construction of the dome base commenced in March 2010. The dome was completed in July 2010. First Light was in February 2011.
