Following a CME which started on 2002 November 26 , RHESSI , the Ramaty High Energy Solar Spectroscopic Imager , observed for 12 hours an X-ray source above the solar limb , at altitudes between 0.1 and 0.3 R _ { S } above the photosphere .
The GOES baseline was remarkably high throughout this event .
The X-ray source ’ s temperature peaked around 10–11 MK , and its emission measure increased throughout this time interval .
Higher up , at 0.7 R _ { S } , hot ( initially > 8 MK ) plasma has been observed by UVCS on SoHO for 2.3 days .
This hot plasma was interpreted as the signature of a current sheet trailing the CME ( ) .

The thermal energy content of the X-ray source is more than an order of magnitude larger than in the current sheet .
Hence , it could be the source of the hot plasma in the current sheet , although current sheet heating by magnetic reconnection within it can not be discounted .

To better characterize the X-ray spectrum , we have used novel techniques ( back-projection-based and visibility-based ) for long integration ( several hours ) imaging spectroscopy .
There is no observed non-thermal hard X-ray bremsstrahlung emission , leading to the conclusion that there is either very little particle acceleration occurring in the vicinity of this post-flare X-ray source , or that either the photon spectral index would have had to be uncharacteristically ( in flare parlance ) high ( \gamma \gtrsim 8 ) and/or the low-energy cutoff very low ( E _ { c } \lesssim 6 keV ) .