The Long Wavelength Array

The Long Wavelength Array (LWA) will be a new multipurpose radio telescope operating in the frequency range 10–88 MHz. Upon completion, the LWA will consist of 53 phased array “stations” distributed over a region about 400 km in diameter in the state of New Mexico. Each station will consist of 256 pairs of dipole-type antennas whose signals are formed into beams, with outputs transported to a central location for high-resolution aperture synthesis imaging. The resulting image sensitivity is estimated to be a few millijanskys (5 $\sigma$, 8 MHz, two polarizations, 1 h, zenith) in 20–80 MHz; with resolution and field of view of (8$^{ \prime\prime}$, 8$^{\circ}$) and (2$^{\prime\prime}$, 2 $^{\circ}$) at 20 and 80 MHz, respectively. Notable engineering features of the instrument, demonstrated in this paper, include Galactic-noise limited active antennas and direct sampling digitization of the entire tuning range. This paper also summarizes the LWA science goals, specifications, and analysis leading to top-level design decisions.