Instruments at the Observatory
There are currently three instruments mounted on the Hanwell site.
The Millennium Telescope
The Millennium telescope is a Newtonian reflector with a 30-inch diameter mirror and a focal length of 180 inches. The light path is folded by an additional flat mirror to send the image to a fixed, horizontal eyepiece at a convenient location for public use.
This telescope is currently in the last stages of construction and, when complete and fully operational, will be the main facility with which the Observatory will then be able to run a full programme of free public star-gazing evenings. The instrument was designed from the beginning, by members of the Observatory project-group, specifically for the prime purpose of such public use - not as a general-purpose observatory telescope, with the public as an afterthought - and this has dictated many of its design features, in order to guarantee ease of access and maximal convenience of use by visitors, many of whom will have had no experience 'at the eyepiece'. When complete, the Millennium Telescope will be one of the largest astronomical telescopes available for public use in the UK and, almost certainly, the largest in the country specifically designed as a dedicated-use public instrument.
In September 2009, the Millennium Telescope was formally opened by Prof. Alec Boksenberg, of the Institute of Astronomy, Cambridge. This 'First Light' event was followed by a celebratory 'Stars and September Woodlands' open weekend.
This is a 12.5-inch aperture f/7 Newtonian reflecting telescope on altazimuth mounting; the square-section wooden 'tube' is not, in fact, a telescope tube in the conventional sense at all but a box-girder for rigidity, all the optics being mounted on the outside for ease of access: the telescope is never under cover but the optics live indoors, being installed in it only at the beginning of each observing session, full set-up and optical adjustment taking no more than 10 minutes... Click here to read more.
The McIver Paton telescope in 2004.
The John Wall Telescope
The John Wall telescope is a 30-inch f/12 refractor. In the entire 400-year history of astronomical telescopes, this is by far the largest refractor (lens telescope, as distinct from a reflector, which uses a concave mirror to do the same job) ever constructed by a single individual. Even today, it ranks as the equal-5th largest refractor anywhere in the world - the largest being only a 40-inch - and the largest ever operated in the British Isles; the last time another refractor as big as this was built (the Thaw photographic telescope, Allegheny Observatory, USA) was in 1914!
That 'single individual' is John Wall, telescope maker extraordinaire and inventor of the 'Crayford' eyepiece-focusser. John did all the development of this wildly unconventional approach to large refractor building, the detailed design-work and all its actual fabrication, both mechanical and optical, single-handedly, in a tiny back-garden workshop and mostly using materials commonly available in the engineering and building trades.
The Observatory owns a number of portable telescopes and binoculars, including a Coronado PST solar telescope, three 4-inch Helios refractors, two 4.7-inch refractors and a 6-inch reflector.