Gaia Focused Product Release: Sources from Service Interface Function image analysis -- Half a million new sources in omega Centauri

TL;DR

This paper presents a new software pipeline that utilizes Gaia's Service Interface Function images to detect and catalog half a million additional sources in the dense omega Centauri region, enhancing Gaia's source inventory.

Contribution

The paper introduces a dedicated SIF CF data reduction pipeline that improves source detection in dense fields, validated against Gaia DR3 and Hubble data, and expands Gaia's catalog in omega Centauri.

Findings

Added 526,587 new sources in omega Centauri

Increased source density by a factor of ten in the cluster center

Extended the catalog depth by three magnitudes in dense regions

Abstract

Gaia's readout window strategy is challenged by very dense fields in the sky. Therefore, in addition to standard Gaia observations, full Sky Mapper (SM) images were recorded for nine selected regions in the sky. A new software pipeline exploits these Service Interface Function (SIF) images of crowded fields (CFs), making use of the availability of the full two-dimensional (2D) information. This new pipeline produced half a million additional Gaia sources in the region of the omega Centauri ($\omega$ Cen) cluster, which are published with this Focused Product Release. We discuss the dedicated SIF CF data reduction pipeline, validate its data products, and introduce their Gaia archive table. Our aim is to improve the completeness of the {\it Gaia} source inventory in a very dense region in the sky, $\omega$ Cen. An adapted version of {\it Gaia}'s Source Detection and Image Parameter Determination software located sources in the 2D SIF CF images. We validated the results by comparing them to the public {\it Gaia} DR3 catalogue and external Hubble Space Telescope data. With this Focused Product Release, 526\,587 new sources have been added to the {\it Gaia} catalogue in $\omega$ Cen. Apart from positions and brightnesses, the additional catalogue contains parallaxes and proper motions, but no meaningful colour information. While SIF CF source parameters generally have a lower precision than nominal {\it Gaia} sources, in the cluster centre they increase the depth of the combined catalogue by three magnitudes and improve the source density by a factor of ten. This first SIF CF data publication already adds great value to the {\it Gaia} catalogue. It demonstrates what to expect for the fourth {\it Gaia} catalogue, which will contain additional sources for all nine SIF CF regions.