The Sun's X‐ray Emission During the Recent Solar Minimum

• DOI: 10.1029/2010eo080002
• Publication Date: 2010-03-10T13:54:42Z
• Authors: Janusz Sylwester; Mirek Kowalinski; Szymon Gburek; Marek Siarkowski; Sergey Kuzin; Frantisek Farnik; Fabio Reale; Kenneth J. H. Phi...

The Sun recently underwent a period of a remarkable lack of major activity such as large flares and sunspots, without equal since the advent of the space age a half century ago. A widely used measure of solar activity is the amount of solar soft X‐ray emission, but until recently this has been below the threshold of the X‐ray‐monitoring Geostationary Operational Environmental Satellites (GOES). There is thus an urgent need for more sensitive instrumentation to record solar X‐ray emission in this range.Anticipating this need, a highly sensitive spectrophotometer called Solar Photometer in X‐rays (SphinX) was included in the solar telescope/spectrometer TESIS instrument package on the third spacecraft in Russia's Complex Orbital Observations Near‐Earth of Activity of the Sun (CORONAS‐PHOTON) program, launched 30 January 2009 into a near‐polar orbit. SphinX measures X‐rays in a band similar to the GOES longer‐wavelength channel.