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| ESPaDOnS | |
|---|---|
| Name | ESPaDOnS |
| Type | Spectropolarimeter |
| Location | Canada–France–Hawaii Telescope |
| Aperture | 3.6 m |
| Wavelength | 370–1050 nm |
| Resolution | R~65,000–80,000 |
| First light | 2004 |
ESPaDOnS ESPaDOnS is a high-resolution cross-dispersed echelle spectropolarimeter deployed at the Canada–France–Hawaii Telescope that enables simultaneous measurement of stellar spectra and polarization, supporting research across astronomy fields such as stellar astrophysics, exoplanet detection, and magnetic field studies. The instrument integrates technologies and collaborations involving institutions like Institut de Recherche en Astrophysique et Planétologie, Observatoire de Paris, Université Laval, and agencies including the National Research Council (Canada), Centre National de la Recherche Scientifique, and the National Science Foundation. It has been used in projects associated with observatories and missions such as Maunakea Observatory, European Southern Observatory, Gaia, and Kepler.
ESPaDOnS was conceived to combine high spectral resolution and precise polarimetry for targets ranging from bright nearby stars to faint pre-main-sequence objects, drawing on heritage from instruments like MuSiCoS, NARVAL, and SOPHIE. The design priorities were informed by scientific programs led by researchers affiliated with Institut d'Astrophysique de Paris, University of Toronto, Observatoire de la Côte d’Azur, and programmes funded by agencies including Canadian Space Agency and Agence Nationale de la Recherche. First light and commissioning campaigns engaged teams from CFHT, Canada-France-Hawaii Telescope Corporation, and collaborators across Europe and North America.
The optical layout employs a fiber-fed cross-dispersed echelle configuration using components and subsystems developed with industry partners and academic labs that have worked on projects such as ESPRIT and HERMES (spectrograph), incorporating an achromatic polarimeter, a Wollaston prism, and beam-exchange optics influenced by earlier instruments like MuSiCoS and ESPaDOnS heritage systems. The detector system uses a large-format CCD array and cryogenic housing with readout electronics similar to those in HARPS and HIRES (Keck) to achieve spectral resolving powers of approximately R~65,000 (polarimetric mode) to R~80,000 (spectroscopic mode) across 370–1,050 nm, enabling simultaneous coverage comparable to instruments such as UVES and FEROS. The instrument includes calibration units with lamps and polarization standards referencing work on calibrators used at ESO, NOAO, and Subaru Telescope.
Installed at the Canada–France–Hawaii Telescope on Maunakea, the instrument is integrated into CFHT’s scheduling, remote operations, and service observing programs that coordinate with facilities like Gemini Observatory, Keck Observatory, and Subaru Telescope. Operations teams include engineers and scientists from CFHT, Université Laval, Laboratoire d'Astrophysique de Marseille, coordinating maintenance cycles, dome/environment management, and instrument control software developed alongside groups experienced with VLT instrument control and Gemini observatory frameworks. Observing modes support visitor and queue programs that have hosted collaborations with researchers from Harvard–Smithsonian Center for Astrophysics, Max Planck Institute for Astronomy, and the University of Cambridge.
ESPaDOnS has been central to studies of stellar magnetism, activity cycles, and dynamo processes in objects observed in programs led by scientists from Institut d'Astrophysique de Paris, University of Exeter, University of St Andrews, and University of Toulouse. It enabled magnetic field detection in Herbig Ae/Be stars and T Tauri systems studied by teams at ESO, Observatoire de Paris, and Instituto de Astrofísica de Canarias, and contributed to exoplanet characterization and atmospheric studies in surveys coordinated with Kepler and follow-up programs by Harvard University and University of California, Berkeley. Results from ESPaDOnS have informed theoretical work cited alongside research from Princeton University, University of Colorado Boulder, Max Planck Institute for Solar System Research, and modeling efforts connected to Cambridge University Press publications and international conferences including meetings of the International Astronomical Union.
Data acquisition is supported by a dedicated pipeline that produces wavelength-calibrated, order-merged spectra and Stokes parameter products, developed with software practices similar to pipelines for HARPS, UVES, and HIRES and maintained by teams at CFHT and partner institutions such as Université Laval and Observatoire de Paris. The reduction chain handles bias, flat-field, scattered light, optimal extraction, and polarimetric demodulation, and the community makes use of analysis tools and libraries developed alongside projects at Centre de Données astronomiques de Strasbourg, Astropy, and data archives at Canadian Astronomy Data Centre.
Calibration strategies utilize hollow cathode lamps, continuum lamps, and polarization standards coordinated with practices at ESO, NOAO, and Subaru Telescope; performance metrics such as throughput, stability, and polarimetric sensitivity are tracked in technical notes produced by CFHT and partners including Institut de Recherche en Astrophysique et Planétologie and Université Laval. The instrument has undergone upgrades and maintenance phases comparable to retrofit efforts at VLT and Keck, with enhancements to fiber feeds, detectors, and software informed by developments at ESO and technology demonstrations at European Southern Observatory facilities, ensuring continued scientific productivity within international observing programs.
Category:Spectrographs Category:Canada–France–Hawaii Telescope