Photosphere Telescope

an astrophysical instrument for photographing the sun, either in integrated (or white) light or over broad spectral regions selected by means of wide-bandpass light filters, in order to study the fine structure, or granulation, of the sun’s photosphere and various solar formations, such as faculae and sunspots.

A photosphere telescope usually consists of a mirror or refractor, with an optimal diameter of 20 to 30 cm, and one or more enlarging cameras, which enable images to be obtained either of the entire sun (10–12 cm in diameter) or of individual sections enlarged several times. The diameter of an image obtained by a photosphere telescope, expressed in centimeters, is approximately equal to the equivalent focal length in meters.

In choosing a site for a photosphere telescope, the proper climatic conditions for solar observations are taken into consideration. The tower structure and the instrument itself incorporate equipment that ensure the least possible image distortion arising from turbulent air currents. Among the essential elements of a photosphere telescope are an automatic guiding system, an image quality analyzer that controls an automatic high-speed shutter, and an exposure meter. Either an ordinary photographic camera or a motion-picture camera can be used.