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Astronomical instruments at Hanwell 12.5" f/7 Newtonian reflector: 'The McIver Paton Telescope' 6" f/6.6 Catadioptric Newtonian |
The Hanwell ObservatoryWhy Hanwell? The permanent site at Hanwell was chosen for this project for the following main reasons. Firstly, we have access to a site in a rural setting, in grounds covering about 20 acres and which are potentially available for activities. Secondly, we already knew the site was suitable for astronomical observing from the observational work done by Christopher Taylor since June 1992 with his 12.5" f/7 Newtonian telescope. Thirdly, the site had been successfully used for group and educational star parties, and especially since 1996 for the Oxford University Department of Continuing Education where astronomical subjects have been taught, and where observations with the 12.5" telescope at Hanwell formed an essential part of this programme. The formative idea for developing the site and building an observatory suitable for public astronomy naturally arose during this period. The site is suitable for a set of permanently mounted telescopes, mostly designed to be weather proof in themselves; thus no permanent buildings are used. The 12.5" and 30" reflectors are designed to be used in the open air with no protective dome or other similar observatory building containing them.
Astronomical instruments at HanwellThe site at Hanwell currently has a 12.5" reflector in situ; we are however in the process of building a large 30" f/6 reflector and expanding the site to house further instruments. Below we list the instruments in current use and those under construction or which have yet to be deployed.
30" f/6 Newtonian reflector
The construction will use an open framework of box girder construction with cross-braces. It will not be a Dobsonian telescope; and indeed we are striving to ensure that the paraboloid will have an excellent figure, so as not to simply end up as a large 'light bucket' with very limited high resolution performance.
You can follow the progress of the building of this instrument by clicking here ....
14" f/6.4 Newtonian reflectorWe already have the complete optical tube assembly of a 14" f/6 Newtonian reflector. This instrument was made by A.E Optics. We are mounting the telescope on a dual alt-azimuth/equatorial mount of a fork type construction to our own design. The whole will be permanently mounted and kept under cover in a specially designed run off box that will seal the instrument and mounting from the elements when not in use.
12.5" f/7 Newtonian reflector: 'The McIver Paton Telescope'The site already has a permanently mounted 12.5" Newtonian reflector. The mirror of the telescope was made by George Calver and is dated 1908 and has an excellent figure. The 1500 lb mount is of alt-azimuth construction while the optical tube assembly is of an unusual box tube 'beam' construction which carries the mirror cell and spider assembly, and top cage for the eyepiece. The telescope was built by a Mr King of Chelmsford in the late 1930's and has been in operation without any kind of protective cover or building ever since. It is named after the late Roderick McIver Paton, F.R.C.S, F.R.A.S, of Chelmsford, who bought the instrument in 1949 and who later with great generosity gave it in 1967 to Christopher Taylor so starting the chain of events that have culminated 30 years later in The Hanwell Observatory. The paraboloid is mounted before each observing session, similarly for the diagonal flat. The other interesting feature is the use of a large circular rotatable disc that holds various eyepieces and simply made, but effective instrumentation currently used for measuring double stars. The telescope also has a Zeiss 11X80 ex-military right-angled finder that sports a massive 80 degree apparent field of view (and 7 degrees on the sky). Plans are under way to modify the mount to track the diurnal motion of the stars using a linked rod, based on the 'Earl of Crawford Mount', together with the use of a set of linked digital setting circles.
6" f/6.6 Catadioptric NewtonianIn addition to the larger Newtonian reflectors available to us, we also have an equatorially mounted 6" (150mm) 'Short Tube' Catadioptric Newtonian. This telescope uses an integral field flattener/corrector lens to combine the benefits of a compact tube length with a long focal length.
4" f/9.8 and 4.75" f/8.3 refractors and 11X80 binocularsWe have several 4" (102mm) and 4.75" (120mm) equatorially mounted refractors and a pair of 11X80 observation binoculars. While these instruments are all portable, we are currently reviewing the site with a view to using these instruments on a few custom built permanent piers. This will provide additional stability and quicker set up time. The equatorial mounts supplied with these telescopes will make ideal camera platforms for simple astrophotography.
30" f/12 refractorWe have been recently given a folded 30" f/12 refractor for our observatory. This very generous offer was made by John Wall of Dartford, Kent, who also built the instrument. We believe it is the largest refractor ever made by an amateur, and ranks the 5th (equal) largest refractor in the world! It currently holds the record as the largest aperture refractor in either professional or amateur hands within the UK, even beating the celebrated 28" refractor at the Royal Greenwich Observatory that previously held this record. It is also all the more remarkable when one realises that that this entire instrument was designed and built by him. The design of the refractor is unusual by being both optically folded (to an overall length of 12 feet) and of the Dialyte design. This latter optical design uses a singlet OG of full aperture with a train of optical correcting elements farther along the optical path. The relative compact size and unusual dialyte design bodes well for a large refractor used in an uncovered site. The instrument was originally located at Dartford (where the following pictures shown below were taken) but has now been rebuilt at Hanwell. On Saturday 18th May 2002 the refractor had first light at Hanwell.
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