Flare Plasma Diagnostics from X-Ray and Ultraviolet Observations

Abstract

We compare the measured values of emission measure EM and temperature T of coronal flare plasma following the GOES, RHESSI, and SDO/AIA satellite observations for the events of July 4, 5, and 7, 2012, in the NOAA 11515 active region. We show that the values of EM and T can vary widely (up to one order of magnitude for EM) depending on the technical features of instruments and processing technique. The maximum difference has been found to be between RHESSI and SDO/AIA measurements for temperature and between GOES and SDO/AIA measurements for EM. We discuss the pros and cons of the approaches used and the practical effects of the resulting numerical estimates for EM and T.