An HST Wide Field Survey of the Galactic Bulge: Overview, Strategy, and First Results

TL;DR

This paper describes an HST imaging survey of the Galactic Bulge, providing high-resolution data to support upcoming Roman Space Telescope exoplanet and stellar population studies.

Contribution

It introduces a coordinated HST survey overlapping with Roman GBTDS, establishing a legacy dataset for Galactic Bulge research.

Findings

Survey covers 1.1 sq. degree area with HST imaging.

Approximately 70% of observations conducted during Cycle 32.

Early results demonstrate the survey's potential for stellar and exoplanet studies.

Abstract

We present an HST imaging survey of a 1.1 sq. degree sky area toward the Milky Way Galactic Bulge. This field significantly overlaps with the upcoming Nancy Grace Roman Galactic Bulge Time Domain Survey (GBTDS). High angular resolution imaging of this area with HST before the start of the Roman Galactic Exoplanet Survey (RGES) will greatly strengthen Roman's ability to characterize detected exoplanet systems, as well as provide a rich and wide-field archive for use as a legacy dataset toward the Galactic Bulge for the broader community. We conduct coordinated-parallel imaging with both wide-field cameras on HST, Wide-field Camera 3 (WFC3) and Advanced Camera for Surveys (ACS), utilizing the F606W and F814W passbands. Approximately 70% of the survey was conducted during HST Cycle 32, with the remaining 30% conducted during Cycle 33. In this paper, the first in a series, we give a general overview of the program and the observing strategy, and present early results. This campaign secures HST's lasting impact on the high-precision study of stellar populations, dynamics, exoplanet systems, interstellar extinction, metallicities, cluster associations, and more toward the center of our Galaxy.