Search for brightness variations in Fe xiv Coronagraph observations of thequiescent solar corona

We use Fe XIV 5303 Angstrom green line images obtained by the Large Angle S pectrometric Coronagraph (LASCO) on board SOHO to search for variability in the quiescent solar corona in the shortest observable timescales. The obse rving program obtained Fe XIV images of a small area of the inner corona ev ery 2 minutes over a period of 1 hr. We present results from two executions of this program taken several months apart. The most obvious variability o bserved in the two sequences is in the form of quasi-steady brightening on timescales of at least an hour. Of particular interest are two compact loop s that are observed to vary significantly during the course of the observat ions. Superposed on the long-term brightening in these loops are statistica lly significant variations on timescales of about 30 minutes. In both loops , the overall brightening is greatest at the apparent loop tops, where the intensity increases by at least 25%. In one loop there appears to be a flow up one of the legs of the loop. We place these observations in context wit h earlier observations of coronal variability, and we discuss the energy re quirements for the observed brightening. Emission measures computed from Fe XIV intensities measured within the two brightening loops are over an orde r of magnitude lower than those typically found for active regions on the s olar disk, which suggests significantly lower average densities. For one of the loops, we measure densities in the range n(e) = (5.0-7.4) x 10(8) cm(- 3). Lower than average densities are expected for the two loops, given that they reach more than 1 pressure scale height above the solar limb.