The development and commissioning of an 8-channel astronomical photometer

Abstract

The development and commissioning of an 8-channel astronomical photometer is described. The design is based on a low dispersion grating spectrograph in which the spectrum produced is focussed onto a mosaic of mirrors which redirect the radiation in the spectral bands into the appropriate detector channels. Filters are used to further define the spectral passbands. The detectors used are photomultipliers, whose response features have been matched to the individual channels. The instrument is under the control of a dedicated microprocessor with a further microprocessor used for data acquisition. The photometer has been employed in an observing programme on the 0.9m James Gregory telescope at St Andrews. Observations of standard uvby stars have allowed transformations equations to be derived for the Strӧmgren system. The eclipsing binary SV Cam has been observed and a revised ephemeris found.