Located in the Owens Valley of California, the OVRO-LWA is an array of dual-polarization broadband dipole antennas covering a frequency range of 15-85 MHz. A major upgrade to the instrument began in 2021. When complete, the upgraded array will consist of 352 fully cross-correlated antennas. The array is configured with a compact core of 243 antennas and 109 outrigger antennas with a maximum antenna spacing of 2.4 km.
The OVRO-LWA supports a broad variety of science, including transient searches, solar science, exoplanet studies, and 21 cm cosmology. Its good uv coverage, long baselines, and wide field-of-view make it particularly suitable for horizon-to-horizon imaging.
The MWA is located in the remote Western Australian outback. The array is sensitive to frequencies of 70-300 MHz. It consists of 4096 dual-polarization dipole antennas grouped in 256 tiles. Each tile includes 16 antennas arranged in a 4x4 grid. The 16 antennas are beamformed to produce a combined tile signal; tiles are then correlated with one another to produce visibilities. The tiles are electronically steerable by introducing differential delays into the antennas’ signal paths. The array consists of a compact pseudo-random core and outrigger antennas. An upgrade in 2016-2017 added two regular hexagonal sub-arrays near the array core and extended the longest baseline to 5 km.
We acknowledge the Wajarri Yamatji people as the traditional owners of the Observatory site.
HERA is a radio array in the South African Karoo purpose-built for 21 cm cosmology measurements. It consists of an array of 350 dishes, each with a diameter of 14 meters. The dishes are constructed from PVC pipes and wire mesh, and a wideband feed is suspended over the center of each. HERA is more compact than either the OVRO-LWA or HERA. 300 of the dishes form a close-packed array in a regular hexagonal configuration with an extent of 300 meters. The remaining 50 outrigger dishes extend the longest baselines to just under 1 km. This compact, regular configuration gives HERA excellent sensitivity to the cosmological 21 cm signal.
The DSA-2000 is a proposed 2000-antenna array to be built in Nevada. It will cover frequencies of 0.7 – 2 GHz and is optimized for surveys of large swaths of the sky. Stay tuned for more information about this exciting upcoming project!