Orwell Astronomical Society (Ipswich)
Introduction to Orwell Park Observatory
Colonel George Tomline was owner of Orwell Park Mansion from 1848 until his death in 1889. He was much interested in the sciences and had Orwell Park Observatory constructed on the east wing of the mansion in 1874 during an extensive re-modelling of the building. He was of enormous wealth and his observatory was built to the highest standard, with many impressive features. It is a testament to the standard of construction that the facility is still operational nowadays. Although much of the land once associated with the mansion has been sold since Tomline's death, the building and grounds nowadays still speak of a glorious past: in addition to the mansion and observatory, there is a clock tower (with Tomline's initials carved as an architectural feature just below the clock face) and a very imposing water tower, used in its era to store water pumped from local springs.
A door at the foot of the observatory tower provides access to a staircase of 111 treads running the height of the building. (Originally the observatory was also served by a hydraulic lift which, unfortunately, was decommissioned in modern times on grounds of safety. Hydraulic pressure for the lift was obtained from the water tower.) The edifice comprises five stories; the two levels of astronomical interest are the belvedere and the equatorial room. The belvedere was originally constructed to provide fine views over the lands of the mansion and the River Orwell. The centre of the belvedere is occupied by large pillar, extending from the foundations to the floor level of the equatorial room, upon which is fixed the Tomline Refractor. A large noticeboard is wrapped around the pillar. Off the belvedere is a small club room, the library and five balconies. The library, opened in 2004, is used to store OASI's collection of books, DVDs and other material available for loan to members. The balconies together offer a view from south through west to north and provide a convenient location for the use of binoculars and small telescopes. OASI stores its smaller telescopes in the belvedere, enabling them to be readily taken out onto the balconies for use. Impressive architectural scrolls separate each balcony from the next.
The equatorial room, dominated by the Tomline Refractor and its massive, cast iron mount, is situated at the top of the spiral staircase. The mount has the unusual form of a distorted cone; this shape enables free movement of the telescope about two axes (right ascension, or RA, and declination) without obstructing the view of any portion of the sky. The RA axis, running diagonally upwards from the base of the mount through to the top, is aligned with the axis of rotation of the Earth; by driving the telescope about it in the opposite direction to that in which the Earth rotates, it is possible to counter the apparent movement of the sky and keep the telescope fixed on any chosen celestial object. The declination axis enables the telescope to be aligned to any object at a particular RA. A hollow in the base of the mount accommodates the RA drive wheel, a large toothed gear fixed to the RA axis. Originally, a weight-powered clockwork mechanism turned the telescope via a shaft with a worm wheel which meshed with the RA drive wheel. However, OASI has retired this system and replaced it with a small electric motor.
The dome of the equatorial room has an aperture which can be opened to see the night sky. When observing, the dome must be rotated periodically so that the aperture remains in alignment with the object under study. The base of the dome sits on top of wheels sunk into the wall of the equatorial room. At the top of the wall, around the circumference of the room, there is a toothed rack. At the base of the dome, a large pulley drives a shaft with a pinion which engages with the rack. Turning the pulley rotates the dome. The inside of the dome is testament again to the quality of construction of the observatory; it is lined with tongue-and-groove hardwood planks, each individually shaped.
The Tomline Refractor has a clear aperture of 258 mm and a focal length of 3890 mm (giving a focal ration of f15.1). The object glass is fitted with a lengthy dew-shield (preventing condensation from forming on the lens on cold, damp winter nights) making the total length of the instrument almost 4.5 m. The mount is of necessity massive in order to support such a large instrument, and the telescope and mount together dominate the equatorial room. The telescope is equipped with simple setting circles, but is not otherwise adorned with the accoutrements enjoyed nowadays by amateurs with modern equipment (slow motion controls, electronic database, computer interface, etc). Using the instrument requires a degree of skill and experience; the Committee of OASI is keen to encourage use of the instrument and arranges informal training for any interested members of OASI.
There are two small rooms off the equatorial room: the map room and the transit chamber. The map room is, in fact, a level in the disused lift shaft which OASI floored-over in the early-1990s. The room is used to store astronomical eyepieces, observing maps and guides, and a PC for running ephemeris programs and other astronomical software. The transit chamber houses a 7.5 cm transit telescope. When the Observatory was commissioned, there was no accessible national time service, and the transit telescope was used to establish local time (and to keep the observatory's chronometers in adjustment) by observing transits of reference stars.
The following photographs show various aspects of Orwell Park and the observatory.
Helen Sharman was Britain's first astronaut. She blasted off from Baikonur Cosmodrome in the former Soviet Union on 18 May 1991 aboard a Soyuz rocket. A few days later, Orwell Park School made radio contact with her as she orbited Earth in the Mir space station; the contact was part of a national link-up involving UK schools. On 14 October 1994, she visited Orwell Park School and observatory and addressed pupils, teachers and their guests.