A frequency-agile interferometer for solar microwave spectroscopy

• Published in: Solar physics Vol. 94; no. 2; pp. 413 - 426
• Main Authors: HURFORD, G. J, READ, R. B, ZIRIN, H
• Format: Journal Article
• Language: English
• Published: Boston, MA Reidel 01.09.1984; Dordrecht
• Subjects: Astronomical and space-research instrumentation; Astronomy; Earth, ocean, space; Exact sciences and technology; Fundamental astronomy and astrophysics. Instrumentation, techniques, and astronomical observations; Spectrometer; Interferometer
• ISSN: 0038-0938; 1573-093X
• DOI: 10.1007/BF00151327

A high-resolution microwave spectrometer has been developed by converting the Owens Valley solar interferometer to frequency-agile operation. The system uses 27-m antennas equipped with phase-locked receivers that can change their observing frequency in 25 or 50 msec. Microwave spectra between 1 and 18 GHz are obtained in a few seconds by successive observations at similar to 86 discrete frequencies. At each frequency, the data are equivalent to the total power from each antenna and the interferometric amplitude and phase. All data are fully calibrated with regard to cosmic sources. The instrument was motivated by the need for better microwave spectral resolution to study plasma parameters, nonthermal electrons, and coronal magnetic field strengths in solar flares and active regions. Early observations with the system are illustrated by a sequence of flare spectra featuring cases with exceptionally narrow continuum bandwidths.