Multi-Instrument Observations of Oscillations in a Solar Flare Fan

We present simultaneous UV and X-ray observations of a coronal quasi-periodic pulsations (QPPs) source, within a loop-top fan structure in the impulsive phase of a long-duration solar flare. The strikingly coherent oscillations (of period approximately 48 seconds) were observed in thermal emission from the Solar Orbiter STIX instrument, synchronized with GOES SXR emission. We also present contemporaneous observations of the fan structure oscillations in IRIS Fe XXI intensity, Doppler and non-thermal velocity, finding QPPs with matching periods, and in phase with, the X-ray data. A sliding raster technique is introduced to push the cadence of the IRIS spectra time series. To our knowledge, this dataset is the first simultaneous UV and X-ray imaging of a coronal QPP source. By combining these multi-instrument datasets, we provide new insights into the origin of QPPs in the solar corona.