Click the above image for the flare movie or watch on youtube!
Glorious days of the Sun with a clover-shaped AR
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Although we can observe some signs of the start of a new solar cycle, the overall X-ray flux from the Sun remains at a low level. We have not seen an M-class flare or larger for more than 2 years. Forgetting the prevailing quiet Sun conditions for a while, let's take a time trip back to mid-December in 2006, when the XRT made its first X-class flare observations. The AR10930 was a large flare-productive region rotated from the East limb early December in 2006. This region produced a number of intensive flares including the following 4 X-class flares: 
However, when the first two X-class flares occurred on December 5th and 6th, XRT was in engineering mode checking the filter wheel performance and was unable to catch them. XRT resumed the observation on December 9th with only a single filter (med-Be). The single use of this relatively thick filter was motivated by safety concerns (CCD protection) rather than for science. But as a result, we could see the whole structure of this clover-shaped active region stably without severe saturation, as shown in the above image. We could also barely catch the last two X-class flares on 13 and 14 December (see the movie). The last X-class flare we observed from the Sun, was in the mid September in 2017. Let's hope that XRT can observe the next X-class flare sometime soon!  Keywords: AR Tracking, Flare Filters: med-Be, thin-Be, C-poly |
(Prepared by Aki Takeda)
The XRT instrument team is comprised of SAO, NASA, JAXA, and NAOJ.
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