For imaging and astrometry at the highest angular resolutions, the ngVLA will include a Long Baseline Array (LBA) consisting of thirty 18-m dishes that will extend across North America and beyond.
The ngVLA LBA antennas will be grouped into 10 clusters of two to four each, and will be located at sites with existing infrastructure, including sites of current VLBA dishes and other radio observatories. LBA Baselines will reach continental scales (Bmax ~ 8860 km), providing angular resolutions as fine as 6 mas at 116 GHz. The LBA is designed to operate both as a stand-alone sub-array, as well as for integrated operations with the main array.
In this poster we will discuss the design and capabilities of the LBA. We will also highlight a sample science use case involving observations of extragalactic water vapor megamasers in the accretion disks of AGNs.
With the ngVLA, such observations will permit a geometric, percent-level measurement of the Hubble Constant. The Next Generation Very Large Array is a design and development project of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.