The Long Wavelength Array:
Steps to Completion

LWA Phase 0 (Complete)

Description Phase 0 of the LWA consists of adding a 74 MHz capacity to the VLA by installing 2-meter dipoles at the prime focus of each antenna and associated receivers. Completed in 1998, this system, though simple and inexpensive, has opened up a new window on the long wavelength universe (see images below). It has already produced a great deal of science (see our list of refereed publications ), as well as valuable experience in long wavelength, high-resolution observation. This instrument is also being used to conduct the VLA Low-frequency Sky Survey (VLSS) which has already mapped half of the sky visible to the VLA at 74 MHz. 74 MHz Dipole on the VLA 74 MHz image of the supernova remnant Cassiopeia A made with the new 74 MHz Pie-Town Link recently implemented by NRL and NRAO. (Image courtesy T. Delaney, PhD Thesis, UMN, 2004.) 74 MHz image of the giant radio galaxy Hydra A (Lane et al. 2004)

LWA Phase 1 (2004-2006)

Description Phase 1 of the LWA consists of the construction of two "development" LWA stations which will form the Long Wavelength Development Array (LWDA). The LWDA will be able to be used in stand-alone mode, or in combination with the VLA 74 MHz system. For more information of the station design, please see the station configuration memo in the LWA memo series. Possible dipole configuration for a LWA station Prototype dipoles used for testing. The "beamformer" will combine the signals from all 256 dipoles in the station into a single beam.

LWA Phase 2 (2006-2008)

Description Phase 2 of the LWA will consist of the two Phase 1 stations plus another 6-7 new stations to be constructed out to baselines of about 150-200 km. This will provide enough baselines to become a stand-alone instrument (apart from the VLA) with full imaging capability. The main purpose is to be a prototype array for testing various ionospheric calibration schemes. However, with an imaging capability at 74 MHz of 4" resolution and 3 mJy/beam noise levels, Phase 2 will provide a huge leap in long wavelength observations, with much scientific potential. For more information on imaging capability, please see the LWA Phase II Imaging Capability memo in the LWA memo series. Possible configuration for the LWA Phase 2 Synthesis UV coverage for the LWA Phase II in stand-alone mode. Simulated image of Cygnus A at 74 MHz with the LWA Phase II. The resolution of 4" is about 5 times better than can be achieved with the current VLA 74 MHz system.

LWA Phases 3 & 4 (2008-2010)

Description LWA Phases 3 and 4 will bring the LWA to completion. First, in Phase 3, the compact core of about 15 stations will be built to fill in the short baselines. In Phase 4, other stations will be added to even out the UV coverage with baselines up to 500 km. At this point, the LWA will consist of 52 stations, with full imaging capability across the entire 23-80 MHz frequency range. Artist's conception of the complete LWA LWA sensitivity and resolution compared to existing long wavelength instruments.