Historical Telescopes

The observatory has three Meade telescopes: two 10" Schmidt-Cassegrain LX200 models and a 7" Maksutov-Cassegrain. These are now used as semi-portable instruments to augment our permanently mounted C14s.

Features include the capability of slewing automatically to any object of known co-ordinates and centre it in the field of view. The LX200s are capable of locating and centring objects with a precision of better than one arcminute, selected from a database of more than 64,000 celestial objects.

Meade : More Information

LX200:
Acquired:	1993
Optics:	Schmidt-Cassegrain
Aperture:	10" (250mm)
Focal Length:	100" (2500mm)
Detector:	Visual and SBIG ST-8XME CCD (1530x1020 array, 9x9 micron pixels)
Additional Instrumentation:	Eyepiece Spectroscopes, 35mm camera body
Field of view:	19 x 12.6 arcmin (CCD)
Controls:	Digital GoTo
Mount:	computer-controlled Meade fork mount

The LX200 has a body is made of aluminium, primary and secondary mirrors of Pyrex glass, and a correcting plate/lens of clear float glass. The instrument as a whole weighs 86 lbs.

The Meade 7" Maksutov-Cassegrain was developed for its excellent imaging capabilities, specifically for lunar, planetary and double-star observations. It has a 7" spherical-meniscus correcting lens of grade BK7 optical glass.

Imaging performance is optimised by the combination of the spherical-meniscus lens, a strongly aspheric f/2.5 primary mirror, and a spherical secondary mirror which multiplies the effective focal length of the primary by a factor of six.

The Allen telescope is a 24-inch reflecting telescope of Ritchey-Chretien design, named in honour of Professor C. W. Allen, the first Perren Professor of Astronomy at University College London (1951–1972). The telescope was inaugurated by Professor D. W. N. Stibbs, Napier Professor of Astronomy at the University of St. Andrews, on 1975 May 22. It was acquired at a cost of £42,000 to replace the original 'Wilson telescope'. donated to UCL in 1925 by Mr. J. G. Wilson (the building is still referred to as 'the Wilson building').

In 2016 The Allen telescope was decommissioned from use at UCLO, in anticipation of the arrival of the Perren telescope.

Allen: More Information

Built/acquired:	1974/5
Refurbished:	1991, 1998
Optics:	Ritchey–Chretien Reflector
Aperture:	24" (600mm)
Effective focal Length:	265" (6742mm, f/11)
Instrumentation:	Custom-built Cassegrain Spectrograph (designed by Mike Dworetsky)
Detector:	Apogee Alta U47 16bit CCD, 1024x1024 array, 13x13 micron pixels
Cass plate scale:	30.6 arcsec/mm (ca. 55 arcmin f.o.v., but not used for imaging)
Drive:	DC servomotors (DFM Engineering)
Mount:	German Equatorial

Description

The Allen, constructed by Ealing Beck, is operated at the Cassegrain focus (although a Coude focus is available in principle; a sketch of the optical layout is available). Many of the technical details are not well documented; although described as a 'Ritchey-Chretien' telescope, the primary mirror may be paraboloidal (not a hyperboloid, as in a true RC configuration). The primary's focal ratio is not known accurately, but is close to f/3. Total weight, including the mount, is approximately 1.5 tonnes.

Refurbishment

Constructed in 1974, the Allen telescope's electronics and drive were replaced in a 1991 with a new computer-controlled system, designed and installed by DFM Engineering of Longmont, Colorado, USA. It was upgraded again in 1998, with a new control system, also designed and installed by DFM Engineering.

Dr W.E. Wilson, FRS, established a private observatory in Daramona, Co. Westmeath, and in 1881 installed a 24-inch reflector by Grubb. Wilson died in 1908, and in 1928 his son, J.G. Wilson, offered the telescope to the University of London. The Wilson telescope was the original instrument of the University of London Observatory on its opening in 1929.

The Wilson was a 24" f/5 reflector with Newtonian and Cassegrain foci. It remained the principal instrument until its retirement in 1974, when it was moved to Liverpool Museum and was replaced with the computer-controlled Allen telescope.

Scans of many photographic plates obtained with the Wilson can be seen in our image galleries.

The Joynson telescope was presented to University College in 1932 by trustees of the late Mr. John Joynson of Liverpool. It is a 6-inch Cooke equatorial refractor and was made in 1863. It was mounted at first at the College's Gower Street site in the Chadwick dome (north), in the place of a 4-inch instrument housed there previously. Having survived the war in the College quadrangle, this 6-inch refractor was moved to the Observatory where it was originally erected under the floor of the dome of the Radcliffe telescope, and used for instruction of students on cloudy nights, whose task it was to measure an artificial double star.

The Joynson telescope was refurbished in 1981, and from 1982 to 1999 was in use mounted on the pier for the Fry telescope during its own refurbishment.

The telescope is on a German Equatorial mounting, similar to the Fry. Since the Fry has taken its place in the new dome building, the Joynson is currently unavailable for use.