The Carlsberg Automatic Meridian Circle (CAMC) is operated jointly by the Copenhagen University Observatory, the Royal Greenwich Observatory and the Real Instituto y Observatorio de la Armada en San Fernando, Spain. Although not one of the Isaac Newton Group of telescopes, it is nevertheless part of the Observatorio del Roque de los Muchachos: a brief description is given in this section.
The CAMC measures the positions and magnitudes of stars, planets and minor planets brighter than m 14.5. The measurements are made with a photoelectric scanning-slit micrometer as the objects cross the north-south meridian of the telescope. The positions and magnitudes of about 600 objects are measured each night to an accuracy of about 0.12 arcsec and 0.04 magnitude. Repeated observations on 4-6 nights produce a mean accuracy of 0.08 arcsec and 0.03 magnitudes.
The telescope is a refractor with an objective of 17.8 cm diameter and focal length of 266 cm. The observing procedure is entirely automatic, with acquisition and on-line data reduction controlled by two HP mini-computers.
The CAMC is not a common-user facility. Requests for observations of particular star lists or solar system objects should be made to one of the three partner institutions. Stars are given a priority between 1 (high) and 6 (low) by an international management committee. A list of several hundred stars given priority 1 will normally be completed within a year. Lists of several thousand stars of lower priority will probably take two or three years to complete.
The results of observations are published annually in catalogues; however, results will be released to users in advance of publication where this is desired. As well as the position and magnitudes, the catalogues contain the improved proper motions of stars derived by combining the CAMC position with previous epoch observations retrieved from a data bank which includes the large photographic catalogues, AC, PPM, Yale, AGK2 and AGK3. The accuracy of the proper motions so derived is about 0.003 arcsec/year.
From its observations of about 50 photometric standards, the CAMC provides nightly values of atmospheric extinction in V for La Palma. A file of these is held in LPINFO and can be consulted via any Starlink node.
Examples of programmes which have been undertaken by the CAMC are as follows: