HARMONI at ELT: Reoptimization of the NGSS natural guide star sensors system for MCAO compatibility

Kjetil Dohlen; David Le Mignant; Anne Bonnefoi; Marc Dubbeldam; Johan Floriot; Iago Funes Vecino; Laurent Jocou; Yoann Richaud; Alexis Carlotti; Zalpha Challita; Anne Costille; Andrew Dunn; David King; Deborah Malone; Guillermo Mercant Rubio; Timothy Morris; Jean-Francois Sauvage; Lazar Staykov; Teodora Aleida Viera Curbelo

arXiv · 2607.20330

HARMONI at ELT: Reoptimization of the NGSS natural guide star sensors system for MCAO compatibility

Kjetil Dohlen·David Le Mignant·Anne Bonnefoi·Marc Dubbeldam·Johan Floriot·Iago Funes Vecino·Laurent Jocou·Yoann Richaud·Alexis Carlotti·Zalpha Challita·Anne Costille·Andrew Dunn·David King·Deborah Malone·Guillermo Mercant Rubio·Timothy Morris·Jean-Francois Sauvage·Lazar Staykov·Teodora Aleida Viera Curbelo

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Abstract

HARMONI is the first-light, adaptive optics assisted, near-IR integral field spectrograph for the ELT. It covers a spectral range from below 800nm to 2400nm with resolving powers from 3000 to 7000 and spatial sampling of 25mas and 6mas. It can operate in three adaptive optics (AO) modes: single conjugate AO (SCAO), high-contrast AO (HCAO), and multi-conjugate AO (MCAO). The project is resuming its final design phase after a rescope design phase that has lasted two years. This paper describes the impact of the rescope on the natural guide star sensors (NGSS) system, imposing wide-ranging changes in particular to the low-order wavefront sensors (LOWFS) previously optimized for LTAO operation as well as on the external support and enclosure (ESE) whose external interfaces have changed. The high-contrast module (HCM) is also deeply affected due to the modified plate scale of the instrument, and the single-conjugate AO sensor (SCAOS) benefits from a reduced patrol field requirement. Description of the changes will be given together with the associated system analysis involving requirements flow-down, revisited functional analysis, and updated product breakdown structure. Elements of the new system management structure and work breakdown will also be included.

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Kjetil Dohlen, David Le Mignant, Anne Bonnefoi, Marc Dubbeldam, Johan Floriot, Iago Funes Vecino, Laurent Jocou, Yoann Richaud, Alexis Carlotti, Zalpha Challita, Anne Costille, Andrew Dunn, David King, Deborah Malone, Guillermo Mercant Rubio, Timothy Morris, Jean-Francois Sauvage, Lazar Staykov, Teodora Aleida Viera Curbelo. 2026-07-22. HARMONI at ELT: Reoptimization of the NGSS natural guide star sensors system for MCAO compatibility. https://arxiv.org/abs/2607.20330

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