The WEAVE-TwiLight-Survey: Expanding WEAVE's Reach to Bright and Low-Surface-Density Targets with a Novel Observing Mode
arXiv:2511.21184 · doi:10.1093/rasti/rzaf060
Abstract
Current-day multi-object spectroscopic surveys are often limited in their ability to observe bright stars due to their low surface densities, resulting in increased observational overheads and reduced efficiency. Addressing this, we have developed a novel observing mode for WEAVE (William Herschel Telescope Enhanced Area Velocity Explorer) that enables efficient observations of low-surface-density target fields without incurring additional overheads from calibration exposures. As a pilot for the new mode, we introduce the WEAVE-TwiLight-Survey (WTLS), focusing on bright exoplanet-host stars and their immediate surroundings on the sky. High observational efficiency is achieved by superimposing multiple low-target-density fields and allocating the optical fibres in this configuration. We use a heuristic method to define fields relative to a central guide star, which serves as a reference for their superposition. Suitable guide fibres for each merged configuration are selected using a custom algorithm. Test observations have been carried out, demonstrating the feasibility of the new observing mode. We show that merged field configurations can be observed with WEAVE using the proposed method. The approach minimizes calibration times and opens twilight hours to WEAVE's operational schedule. WTLS is built upon the new observing mode and sourced from the ESA PLATO long-duration-phase fields. This survey will result in a homogeneous catalogue of approximately 6300 bright stars, including 62 known planet hosts, laying the groundwork for future elemental abundance studies tracing chemical patterns of planetary formation. This new observing mode (WEAVE-Tumble-Less) expands WEAVE's capabilities to rarely used on-sky time and low-density field configurations without sacrificing efficiency.
References in corpus (13)
- The Gaia mission
- The Transiting Exoplanet Survey Satellite
- The Radial Velocity Experiment (RAVE): first data release
- The wide-field, multiplexed, spectroscopic facility WEAVE: Survey design, overview, and simulated implementation
- The all-sky PLATO input catalogue
- The PLATO field selection process I. Identification and content of the long-pointing fields
- Host-star and exoplanet compositions: a pilot study usinga wide binary with a polluted white dwarf
- The PLATO field selection process. II. Characterization of LOPS2, the first long-pointing field
- MELCHIORS: The Mercator Library of High Resolution Stellar Spectroscopy
- Ariel stellar characterisation II. Chemical abundances of carbon, nitrogen, and oxygen for 181 planet-host FGK dwarf stars
- Ariel stellar characterisation III. Fast rotators and new FGK stars in the Ariel Mission Candidate Sample
- Where in the Milky Way Do Exoplanets Preferentially Form?
- A Link Between Rocky Planet Density and Host Star Chemistry