Array Configuration

Reference Configuration

The main array configuration will consist of 214 18m antennas at the approximate locations shown in Figure 1. The array collecting area is distributed to provide high surface brightness sensitivity on a range of angular scales spanning from approximately 1000 to 10 mas (see Table below). In practice, this means a core with a large fraction of the collecting area in a randomized distribution to provide high snapshot imaging fidelity, and arms extending asymmetrically out to ~1000 km baselines, filling out the (u, v)-plane with Earth rotation and frequency synthesis.

The array configuration is practical, accounting for logistical limitations such as topography and utility availability. Investigations are underway to improve the imaging sensitivity and fidelity while accounting for additional limitations such as local RFI sources and land management/availability.

Radial Distribution of Collecting Area
Radius Collecting Area Fraction
0 km < R < 1.3 km 44%
1.3 km < R < 36 km 35%
36 km < R < 1000 km 21%

An auxiliary short baseline array (SBA) of 19 reflector antennas of 6m aperture will be sensitive to a portion of the larger angular scales undetected by the main array.  The SBA will provide spacings from 11m to 60m, providing comparable surface brightness sensitivity to the main array, in equal observing time, when the main array is (u, v)-tapered to the natural resolution of the SBA. This allows for commensal observing, and more importantly, full cross-correlation and cross-calibration of the SBA and main array. The array distribution is semi-randomized to improve the point spread function.

The SBA will be combined with 4 18m (main-array) antennas used in total power (TP) mode to completely fill in the central hole in the (u, v)-plane left by the 6m dishes. It is a design goal to share the mount design of the 18m interferometric array antennas and the TP antennas, but this will require further study.

Preliminary (revB) ngVLA Configuration Collage

A collage showing the preliminary (revB; April 24, 2018) ngVLA configuration.

Note: Configuration coordinate files for simulation can be found on the Tools Page.