We analyze the temporal variation of temperature and emission measure at the top of a coronal loop system observed with the Transition Region and Coronal Explorer (TRACE). Loops delineate regions of highly localized heating and are thus typically the focus of coronal heating theories. The analyzed data consist of observations in the 171A and 195 A passbands taken at a cadence of ～10 min obtained on May 15, 1999 during an observing campaign. The temperature and emission measure diagnostic is based in the 171A / 195 A filter-ratio technique. The loop system evacuates after the plasma at the top of the loops has cooled. Estimates of the timescales of energy losses by radiation and by conduction clearly suggest that the cooling is mainly due to radiation losses.
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