The Large Angle and Spectrometric COronagraph (LASCO) instrument is one of 11 instruments included on the joint NASA/ESA SOHO (Solar and Heliospheric Observatory) spacecraft. SOHO was launched on 2 December 1995 at 0808 UT (0308 EST) from the Kennedy Space Center, Cape Canaveral, Florida. The LASCO instrument is a set of three coronagraphs that image the solar corona from 1.1 to 32 solar radii. It is convenient to measure distances in terms of solar radii. One solar radius is about 700,000 km, 420,000 miles or 16 arc minutes. A coronagraph is a telescope that is designed to block light coming from the solar disk, in order to see the extremely faint emission from the region around the sun, called the corona.

The essential questions of solar physics to be addressed by LASCO are:

  • How is the corona heated?
  • Where and how is the solar wind accelerated?
  • What causes coronal transients, and what role do they play in the evolutionary development of large-scale coronal patterns?

LASCO was built by an international consortium of four institutions in four different countries:

The LASCO electronics box also provides services for an additional experiment called the Extreme Ultraviolet Imaging Telescope (EIT). Since the two experiments are closely coupled, status and other general information can be obtained at this site, but more specific information is available from the EIT home page.

For more information on LASCO see the LASCO User Handbook . A short summary of LASCO is available. Also, a special issue on SOHO was published by Solar Physics, December 1995.