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N. E. Kassim (NRL), R. A. Perley (NRAO), W. C. Erickson (U.MD, NRL), T. J. W. Lazio (NRL)
Radio astronomy was discovered by Jansky at long wavelengths (LW = 2--20 m, 15--150 MHz). After the pioneering work at LWs, LW radio astronomy was largely neglected because ionospheric structure limited interferometric baselines to a few km. In turn this restricted the angular resolution to tens of arcminutes to degrees and the sensitivity to Jy levels and higher because of source confusion. As a result, the LW regime has been among the most poorly explored, despite a variety of planetary, solar, Galactic, and extragalactic emission, absorption, and scattering phenomena that are frutifully studied at LWs.
A new 74-MHz observing system at the VLA, co-developed by the Naval Research Laboratory and the National Radio Astronomy Observatory, has now shattered this ``ionospheric barrier'': The LW VLA can image large fields (> 10 degrees) at relatively high sensitivity (< 100 mJy) and angular resolution (sub-arcminute) in a few hours integration. We demonstrate the system's capabilities using some of its first images.
We also discuss plans for the Long Wavelength Array (LWA), an instrument capable of arcsecond resolution (i.e., baseline lengths of hundreds of kilometers) and sub-milliJansky sensitivities.
Additional papers at this meeting describe the possibilities of the LWA for solar radar studies (Lazio et al.) and passive solar observations (Gopalswamy et al.).
Basic research in radio astronomy at the NRL is supported by the Office of Naval Research. The NRAO is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.
If the author provided an email address or URL for general inquiries,
it is as follows:
http://rsd-www.nrl.navy.mil/7213/lazio/decade_web/