A Cross-Correlation based Spectral Kurtosis RFI Detector

Accurate flagging of Radio Frequency Interference (RFI) is necessary to recover instrumental efficiency and avoid false astronomical detections. Spectral Kurtosis ((SK)̂) is a popular operator in RFI flagging for radio astronomy due to its detection sensitivity to non-Gaussian emissions and its competitive computational cost. Most (SK)̂ detection pipelines are applied to single antennas or autocorrelations products. This paper investigates the application of the (SK)̂ to antennas cross-correlations, and demonstrates an improved detection performance compared to the auto-correlation-based approaches

New Interactive Solar Flare Modeling and Advanced Radio Diagnostics Tools

The coming years will see routine use of solar data of unprecedented spatial and spectral resolution, time cadence, and completeness in the wavelength domain. To capitalize on the soon to be available radio facilities such as the expanded OVSA, SSRT and FASR, and the challenges they present in the visualization and synthesis of the multi-frequency datasets, we propose that realistic, sophisticated 3D active region and flare modeling is timely now and will be a forefront of coronal studies over the coming years. Here we summarize our 3D modeling efforts, aimed at forward fitting of imaging spectroscopy data, and describe currently available 3D modeling tools. We also discuss plans for future generalization of our modeling tools.Comment: 4 pages; IAU Symposium # 274 "Advances in Plasma Astrophysics"; typo remove

A Cross-Correlation based Spectral Kurtosis RFI Detector

Accurate flagging of Radio Frequency Interference (RFI) is necessary to recover instrumental efficiency and avoid false astronomical detections. Spectral Kurtosis ((SK)̂) is a popular operator in RFI flagging for radio astronomy due to its detection sensitivity to non-Gaussian emissions and its competitive computational cost. Most (SK)̂ detection pipelines are applied to single antennas or autocorrelations products. This paper investigates the application of the (SK)̂ to antennas cross-correlations, and demonstrates an improved detection performance compared to the auto-correlation-based approaches

Cold, tenuous solar flare: acceleration without heating

We report the observation of an unusual cold, tenuous solar flare, which reveals itself via numerous and prominent non-thermal manifestations, while lacking any noticeable thermal emission signature. RHESSI hard X-rays and 0.1-18 GHz radio data from OVSA and Phoenix-2 show copious electron acceleration (10^35 electrons per second above 10 keV) typical for GOES M-class flares with electrons energies up to 100 keV, but GOES temperatures not exceeding 6.1 MK. The imaging, temporal, and spectral characteristics of the flare have led us to a firm conclusion that the bulk of the microwave continuum emission from this flare was produced directly in the acceleration region. The implications of this finding for the flaring energy release and particle acceleration are discussed.Comment: ApJ Letters accepted; 5 figure