THE LARGE-ANGLE SPECTROSCOPIC CORONAGRAPH (LASCO)

The Large Angle Spectroscopic Coronagraph (LASCO) is a three coronagra ph package which has been jointly developed for the Solar and Heliosph eric Observatory (SOHO) mission by the Naval Research Laboratory (USA) , the Laboratoire d'Astronomie Spatiale (France), the Max-Planck-Insti tut fur Aeronomie (Germany), and the University of Birmingham (UK). LA SCO comprises three coronagraphs, C1, C2, and C3, that together image the solar corona from 1.1 to 30 R. (C1: 1.1 - 3 R., C2: 1.5 - 6 R., an d C3: 3.7 - 30 R.) The C1 coronagraph is a newly developed mirror vers ion of the classic internally-occulted Lyot coronagraph, while the C2 and C3 coronagraphs are externally occulted instruments. High-resoluti on imaging spectroscopy of the corona from 1.1 to 3 R. can be performe d with the Fabry-Perot interferometer in C1. High-volume memories and a high-speed microprocessor enable extensive on-board image processing . Image compression by a factor of about 10 will result in the transmi ssion of 10 full images per hour.