Thermodynamic history of a solar active region observed in X-rays

We have investigated the structure and energy content of an active coronal volume during its early history using soft X-ray images secured with the Aerospace/MSFC glancing-incidence telescope on Skylab. During the late stages of EFR activity the maximum temperatures exceeded 6.5 x 10/sup 6/ K. At that time, the time rate of change of thermal energy content was about -10/sup 25/ ergs s/sup -1/ and was comparable to the rate of energy loss by radiation. Fluctuations in the energy content of the X-ray source region imply that this coronal active region was probably not in energy equilibrium during the five days of observation. (AIP)