Then and Now: Ten Years After EIT's First Light
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SOHO's twelve instruments began obtaining data just a few days after launch, 1995 December 2. The Extreme ultraviolet Imaging Telescope (EIT) was kept at a higher temperature than the rest of the spacecraft for a month after launch, however, in an attempt to outgas any water vapor and other contaminants that might have adhered to the telescope interior or detector, so EIT's "first light" was obtained on 2006 January 2. We present those original images, as well as images from January 2 of this year for comparison.
EIT is the only orbiting telescope that provides continual imaging of the entire solar disk and low corona in plasma at temperatures of 60,000 to 2.5 million Kelvin --- and has been for the last ten years, except forSOHO's brief "vacations" in 1998 and 1999. In conjunction with SOHO's LASCO coronagraphs, EIT provides two to three days' advance warning of solar storms approaching the earth.
EIT will be joined later this year by the Extreme UltraViolet Imagers (EUVIs) in the SECCHI instruments on board the NASA STEREOspacecraft, and in late 2008 by the Atmospheric Imaging Assembly (AIA) on the Solar Dynamics Observatory (SDO) spacecraft. The TRACE Small Explorer images limited areas of the Sun at five times the spatial resolution of EIT; the EUVIs will have twice, and the AIA telescopes four times, the resolution of EIT.
EIT was built and is operated by a consortium of French, Belgian, and US institutions, under the leadership of Dr. Jean-Pierre Delaboudinière, who recently retired as Principal Investigator (PI). The new PI is Dr. Frédéric Auchere of the Institut d'Astrophysique Spatiale in Orsay, France.
- EIT homepage (EIT team)