Introduction

The Society has many facilities available to its members and its guests, including a library, Palomar sky survey plates, etc.  Its prized possessions are the following:
 

The 24 Inch Telescope

The Society owns a domed 24 inch (0.6m) reflecting telescope, built by John Wall.  Members who have passed a test of competence have keys to the observatory and unrestricted access.  The general public may have access by special arrangement and is often open on Society open days.  It has proven very popular with local school and scout trips.

The Hewitt Camera Archive

The Hewitt Camera Archive is a collection of about 11,000 photographic plates in the custody  of the Society at Crayford.  The plates were taken between 1965 and 1990 using Schmidt Cameras, specially designed for artificial satellite work by Joseph Hewitt of the Royal Radar Establishment at Malvern, England. One of these cameras was moved to Siding  Spring, Australia and, from 1982 onwards, nearly 4,000 plates were taken with it; the remaining 7,000 or so plates being taken from various sites in the UK.  After the closure of the Royal Greenwich Observatory at Herstmonceux, all the plates (including the Australian ones) were placed under the custody of the Society by the British Astronomical Association.

The original purpose of the plates was to image man-made satellites, therefore each image was untracked and was usually chopped (to allow the satellite's speed to be estimated).  Each exposure is circular of diameter 10 cm, which represents 10 degrees of sky. Stars as faint as magnitude 11 are generally visible, and in some cases stars of magnitude 13 can be made out. Since certain times of night and certain times of year are more favourable than others for satellite work, the distribution of plates across the celestial sphere is not uniform.  On average, a given star in the northern hemisphere will appear on about 30 plates, and in the southern, on about 16 plates.  Stars near the poles are generally better represented than those near the celestial equator.  The Society has created a computerised index to all the plates, so plates showing a particular star or a particular satellite can be readily identified.

The Archive is are available, by prior arrangement with the Secretary of the Society, Dr Michael Rushton, for use by any member of the astronomical community, amateur or professional.  Potential applications include research into variable stars, the orbits of minor planets and studies of artificial satellites (as originally intended).  A more complete description of the Archive, together with the use of the index is given in the paper "The Hewitt Camera Archive at Crayford", J J Howarth, Journal of the British Astronomical Association, 102, 6, 1992, pp 343 - 350.