FAQ for ISO 19115 and 19115-2 Alternate Views: Get Data, FAQ, ISO Rubric, DOI Rubric, CSW, HTML, Components, XML
Solar Corona
The solar corona is the outermost layer of the sun’s atmosphere--a very hot halo (millions of degrees), that, in the form of the solar wind, extends well past the Earth’s orbit. The corona is observed in detail during solar eclipses. In practice, the corona is observed routinely by ground-based and satellite coronagraphs in the red line Fe X (634.7nm -- ten times ionized iron line) and the green line Fe XIV (530.3 nm -- 14 times ionized iron line), and occasionally in the high energy yellow line Ca XV (569.4 nm -- 15 times ionized Calcium line). White light observations of the solar corona are also made routinely, and used for detecting coronal mass ejections (CMEs) that may affect the Earth. The coronagraph is a special telescope with an occulting disk to block the direct light of the sun and thus able to measure the brightness of the fainter and less dense corona. The intensities are recorded in tabular form, historically in 5-degree increments around the sun’s disk. The data center holds data in analog form from 12 stations covering the period 1943 to present. Currently, 2 stations send daily coronal scans to the data center. A coronal activity index from Lomnicky Stit, Slovak Republic, 1939-present, is also available. Coronal data exhibit the 11 year solar cycle variation. Solar X-ray measurements since 1991 by the Yohkoh and GOES Solar X-ray Imager (SXI) satellites allow continuous coverage of the constantly changing hot solar corona.