LASCO Large Angle and Spectrometric Coronagraph
Encyclopedia
The Large Angle and Spectrometric Coronagraph (LASCO) is one of a number of instruments aboard the Solar and Heliospheric Observatory
satellite (SOHO). LASCO consists of three solar coronagraph
s with nested fields of view:
The first principal investigator was Dr. Guenter Brueckner
. These coronagraphs monitor the solar corona by using an optical system to create, in effect, an artificial solar eclipse
. The white light coronagraphs C2 and C3 produce images of the corona over much of the visible spectrum, while the C1 interferometer produces images of the corona in a number of very narrow visible wavelength bands.
of about 26 seconds.
, when a digital camera
was something very special. Sometimes disturbances do happen.
There are two kinds that repeatedly occur:
Solar and Heliospheric Observatory
The Solar and Heliospheric Observatory is a spacecraft built by a European industrial consortium led by Matra Marconi Space that was launched on a Lockheed Martin Atlas IIAS launch vehicle on December 2, 1995 to study the Sun, and has discovered over 2100 comets. It began normal operations in May...
satellite (SOHO). LASCO consists of three solar coronagraph
Coronagraph
A coronagraph is a telescopic attachment designed to block out the direct light from a star so that nearby objects – which otherwise would be hidden in the star's bright glare – can be resolved...
s with nested fields of view:
- C1 - a Fabry–Pérot interferometer coronagraph imaging from 1.1 to 3 solar radii
- C2 - a white light coronagraph imaging from 2 to 6 solar radii
- C3 - a white light coronagraph imaging from 3.7 to 32 solar radii
The first principal investigator was Dr. Guenter Brueckner
Guenter Brueckner
Guenter E. Brueckner was a solar physicist who spent much of his career at the US Naval Research Lab. His life's efforts included research into aspects of the sun relevant to radio signal quality, terrestrial weather, space weather and applications of plasmas such as in fusion energy...
. These coronagraphs monitor the solar corona by using an optical system to create, in effect, an artificial solar eclipse
Solar eclipse
As seen from the Earth, a solar eclipse occurs when the Moon passes between the Sun and the Earth, and the Moon fully or partially blocks the Sun as viewed from a location on Earth. This can happen only during a new moon, when the Sun and the Moon are in conjunction as seen from Earth. At least...
. The white light coronagraphs C2 and C3 produce images of the corona over much of the visible spectrum, while the C1 interferometer produces images of the corona in a number of very narrow visible wavelength bands.
Shutter speed
LASCO C3, the clear coronagraph picture, has a shutter time of about 19 seconds. LASCO C2, the orange picture, has a shutter speedShutter speed
In photography, shutter speed is a common term used to discuss exposure time, the effective length of time a camera's shutter is open....
of about 26 seconds.
Resolution
The three LASCO cameras have a resolution of one megapixel. The base unit of LASCO's pictures are blocks of 32x32 pixels. If only one bit is missing, as it could occur due to disturbances, the whole block is gated out.Disturbances
The LASCO instruments are not the newest. They were built in the late 80s1980s
File:1980s decade montage.png|thumb|400px|From left, clockwise: The first Space Shuttle, Columbia, lifted off in 1981; American President Ronald Reagan and Soviet leader Mikhail Gorbachev eased tensions between the two superpowers, leading to the end of the Cold War; The Fall of the Berlin Wall in...
, when a digital camera
Digital camera
A digital camera is a camera that takes video or still photographs, or both, digitally by recording images via an electronic image sensor. It is the main device used in the field of digital photography...
was something very special. Sometimes disturbances do happen.
There are two kinds that repeatedly occur:
- Blackouts and Whiteouts, in broken lines, circle-like shapes, or over the whole picture. They are caused by the electronics box. There has never been a firmware update, since it was judged as too sensitive changing the flight-software.
- Black and white pixels, occurring in patterns, without pattern or alone. Those "missing blocks" are telemetry dropouts, caused by radio interference or a disturbance in the data transfer to Goddard Space Flight CenterGoddard Space Flight CenterThe Goddard Space Flight Center is a major NASA space research laboratory established on May 1, 1959 as NASA's first space flight center. GSFC employs approximately 10,000 civil servants and contractors, and is located approximately northeast of Washington, D.C. in Greenbelt, Maryland, USA. GSFC,...
.