_version_ 1866912754839846912
author Hajnik, Thomas
Walton, Nicholas A.
D'Ago, Giuseppe
Bonifacio, Piercarlo
Dalton, Gavin
Dominguez-Palmero, Lilian
Gafton, Emanuel
Irwin, Mike J.
Pico, Sergio
Terrett, David
Ardern-Arentsen, Anke
Sanchez-Janssen, Ruben
Aguado, David S.
Aguerri, J. Alfonso L.
Prieto, Carlos Allende
Balcells, Marc
Benn, Chris
Bragaglia, Angela
Caffau, Elisabetta
Carrasco, Esperanza
Carrera, Ricardo
Desidera, Silvano
Gansicke, Boris T.
Hughes, Sarah
Jin, Shoko
Lewis, Ian
Molaeinezhad, Alireza
Murphy, David N. A.
Schallig, Ellen
Trager, Scott
Vallenari, Antonella
author_facet Hajnik, Thomas
Walton, Nicholas A.
D'Ago, Giuseppe
Bonifacio, Piercarlo
Dalton, Gavin
Dominguez-Palmero, Lilian
Gafton, Emanuel
Irwin, Mike J.
Pico, Sergio
Terrett, David
Ardern-Arentsen, Anke
Sanchez-Janssen, Ruben
Aguado, David S.
Aguerri, J. Alfonso L.
Prieto, Carlos Allende
Balcells, Marc
Benn, Chris
Bragaglia, Angela
Caffau, Elisabetta
Carrasco, Esperanza
Carrera, Ricardo
Desidera, Silvano
Gansicke, Boris T.
Hughes, Sarah
Jin, Shoko
Lewis, Ian
Molaeinezhad, Alireza
Murphy, David N. A.
Schallig, Ellen
Trager, Scott
Vallenari, Antonella
contents 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.
format Preprint
id arxiv_https___arxiv_org_abs_2511_21184
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle The WEAVE-TwiLight-Survey: Expanding WEAVE's Reach to Bright and Low-Surface-Density Targets with a Novel Observing Mode
Hajnik, Thomas
Walton, Nicholas A.
D'Ago, Giuseppe
Bonifacio, Piercarlo
Dalton, Gavin
Dominguez-Palmero, Lilian
Gafton, Emanuel
Irwin, Mike J.
Pico, Sergio
Terrett, David
Ardern-Arentsen, Anke
Sanchez-Janssen, Ruben
Aguado, David S.
Aguerri, J. Alfonso L.
Prieto, Carlos Allende
Balcells, Marc
Benn, Chris
Bragaglia, Angela
Caffau, Elisabetta
Carrasco, Esperanza
Carrera, Ricardo
Desidera, Silvano
Gansicke, Boris T.
Hughes, Sarah
Jin, Shoko
Lewis, Ian
Molaeinezhad, Alireza
Murphy, David N. A.
Schallig, Ellen
Trager, Scott
Vallenari, Antonella
Instrumentation and Methods for Astrophysics
Earth and Planetary Astrophysics
Solar and Stellar Astrophysics
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.
title The WEAVE-TwiLight-Survey: Expanding WEAVE's Reach to Bright and Low-Surface-Density Targets with a Novel Observing Mode
topic Instrumentation and Methods for Astrophysics
Earth and Planetary Astrophysics
Solar and Stellar Astrophysics
url https://arxiv.org/abs/2511.21184