The VLBA Calibrator Search for the BeSSeL Survey

TL;DR

This study used the VLBA to identify compact radio sources near the Galactic plane to serve as calibrators for parallax measurements in the BeSSeL survey, improving the precision of Galactic structure mapping.

Contribution

It presents a new survey of radio sources near the Galactic plane, identifying 199 suitable VLBA calibrators for the BeSSeL project, based on specific selection criteria from NVSS and CORNISH catalogs.

Findings

199 sources detected with VLBA, suitable as calibrators

Most undetected sources are likely extragalactic

Enhanced calibration sources for Galactic parallax measurements

Abstract

We present the results of a survey of radio continuum sources near the Galactic plane using the Very Long Baseline Array (VLBA). Our observations are designed to identify compact extragalactic sources of milliarcsecond size that can be used for parallax measurements in the Bar and Spiral Structure Legacy Survey. We selected point sources from the NVSS and CORNISH catalogs with flux densities above 30 mJy and within $1.5\degr$ of known maser targets. Of the 1529 sources observed, 199 were detected. For sources detected on 3 or more baselines, we determined accurate positions and evaluated their quality as potential calibrators. Most of the 1330 sources that were not detected with the VLBA are probably of extragalactic origin.