# The Second LBA Calibrator Survey of southern compact extragalactic radio sources - LCS2

## TL;DR

This paper presents the second catalog of precise positions and flux densities for 1100 compact extragalactic radio sources in the southern sky, derived from VLBI observations to enhance astrometric and astrophysical studies.

## Contribution

It provides a new, extensive catalog of southern compact radio sources with high-precision positions and flux densities, expanding the available data for the southern hemisphere.

## Key findings

- Median position uncertainty of 3.5 mas.
- Over sixfold increase in known sources south of -40 deg declination.
- Enhanced data for VLBI, Gaia, and space navigation applications.

## Abstract

We present the second catalogue of accurate positions and correlated flux densities for 1100 compact extragalactic radio sources that were not observed before 2008 at high angular resolution. The catalogue spans the declination range -90 deg, -30 deg and was constructed from nineteen 24-hour VLBI observing sessions with the Australian Long Baseline Array at 8.3 GHz. The catalogue presents the final part of the program that was started in 2008. The goals of that campaign were 1) to extend the number of compact radio sources with precise coordinates and measure their correlated flux densities, which can be used for phase referencing VLBI and ALMA observations, geodetic VLBI, search for sources with significant offsets with respect to Gaia positions, and space navigation; 2) to extend the complete flux-limited sample of compact extragalactic sources to the Southern Hemisphere; and 3) to investigate the parsec-scale properties of sources from the high-frequency AT20G survey. The median uncertainty of the source positions is 3.5 mas. As a result of this VLBI campaign, the number of compact radio sources south of declination -40 deg which have measured VLBI correlated flux densities and positions known to milliarcsecond accuracy has increased by over a factor of 6.