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Thanks to a Major Flare Watch issued by the Max Millennium group concerning Active Region 10030 (also referred to as just AR 30) since Friday, July 12, a powerful (X3) flare was caught by the Coronal Diagnostic Spectrometer (CDS) instrument on Monday, July 15, just after 20:00 UT. With its limited field of view, CDS rarely catches flares "right on". In fact, they normally try to avoid them to spare the detectors from the additional wear. For these alerts, though, a special observing program with short exposures can be used. See also this hot shot page for more CDS observations of flares, including a description of what is being observed. Examples of earlier ground and space based observations can be found in this hot shot page.
The flare was also observed by another instrument on SOHO, the Extreme ultraviolet Imaging Telescope (EIT), as well as by the Transition Region And Coronal Explorer (TRACE) spacecraft. No doubt the flare was also observed by ground observatories, thanks to the Major Flare Watch.
The flare was associated with an Earth-directed full halo Coronal Mass Ejection (CME), observed by both the Large Angle and Spectrometric Coronagraph (LASCO) and Ultraviolet Coronagraph Spectrometer (UVCS) on board SOHO. The shock from the CME passed by SOHO at about 15:29 UT on July 17, as observed by the CELIAS/MTOF Proton Monitor.
Picture credits: SOHO/CDS, SOHO/EIT (ESA & NASA); TRACE (NASA)