Lasco

LASCO, an acronym for Large Angle and Spectrometric Coronagraph, is an instrument package aboard the Solar and Heliospheric Observatory (SOHO). Launched in 1995 as a joint mission of the European Space Agency and NASA, LASCO is designed to study the outer solar atmosphere, the corona, by blocking direct sunlight with an occulting disk and capturing the scattered light from the corona. The instrument consists of three coronagraphs—C1, C2, and C3—that cover progressively larger fields of view, roughly from about 1 to 30 solar radii. Observations are typically made in visible light, with polarized brightness measurements providing density information.

LASCO's images have enabled the continuous monitoring of coronal mass ejections and other solar activity, contributing to space weather forecasting. The coronagraphs have also been instrumental in the discovery of thousands of comets passing near the Sun, particularly the Kreutz sungrazing family; these comets are often visible as faint trailing objects in LASCO images.

Data from LASCO are archived and publicly accessible via the SOHO LASCO data center, supporting ongoing solar physics research and education. The instrument's longevity and data set have made it one of the most productive solar observation facilities in operation.

Note: LASCO is also used as an acronym in other contexts and may refer to organizations or names unrelated to the solar instrument; in astronomy, however, LASCO specifically denotes the Large Angle and Spectrometric Coronagraph on SOHO.