Improved astrometry for the Bohannan & Epps catalogue

TL;DR

This paper improves the astrometric accuracy of the Bohannan & Epps catalogue by re-identifying targets in digital images and matching them to the UCAC4 catalogue, enabling reliable cross-matching with modern surveys.

Contribution

Provides sub-arcsecond astrometry for all entries in the BE74 catalogue, correcting previous identification errors and enhancing data reliability.

Findings

Almost all BE74 stars now have sub-arcsecond astrometry.

Identification errors in literature highlight the need for precise astrometry.

Improved data facilitates accurate cross-matching with modern surveys.

Abstract

Aims: Accurate astrometry is required to reliably cross-match 20th-century catalogues against 21st-century surveys. The present work aims to provide such astrometry for the 625 entries of the Bohannan & Epps (BE74) catalogue of H$\alpha$ emission-line stars. Methods: BE74 targets have been individually identified in digital images and, in most cases, unambiguously matched to entries in the UCAC4 astrometric catalogue. Results: Sub-arcsecond astrometry is now available for almost all BE74 stars. Several identification errors in the literature illustrate the perils of relying solely on positional coincidences using poorer-quality astrometry.