Canadian collaboration brings world’s biggest FT spectrometer to light

Quebec, QC – Université Laval and ABB have embarked on the final phase of a major collaborative project for an astronomical measurement instrument they say will offer unsurpassed precision. Named SITELLE (Wide-field Imaging Fourier Transform Spectrometer), the instrument integrates several advanced technologies that will be installed at the Canada-France-Hawaii Telescope (CFHT), one of the most productive telescopes in the world, located at the summit of Mauna Kea on Hawaii’s Big Island. SITELLE will analyze the characteristics of the light emitted by each component of large astronomical objects such as nebulae and galaxies, making it possible to analyze these celestial objects as never before.

The design of SITELLE presented a tremendous technical challenge. The heart of the instrument is based on the displacement of a mirror to an accuracy of one millionth of a millimeter assisted by laser beams. SITELLE must operate in difficult weather conditions at 4,200 meters/13,778 feet above sea level at the top of the highest volcano in the Hawaiian archipelago, while following the course of the stars in the sky. The instrument is the result of the expertise of the team headed by astrophysicist Laurent Drissen and optical design specialist Simon Thibault, both professors at the Faculty of Science and Engineering from Université Laval, and the know-how of the CFHT team in wide-field cameras and ABB’s Measurement & Analytics team the prime contractor of the project in the field of spectroscopy and optical instrumentation.

“We are very proud to have built this new camera with Université Laval, [which] will be the pride of the CFHT internationally. It is the result of a long-standing collaboration between Université Laval and ABB. Standing 2 meters tall, weighing more than 400 kg/882 lbs, with lenses the size of dinner plates, SITELLE will be the largest and most ambitious Fourier Transform imaging spectrometer ever built and the most powerful of its kind in astronomy,” said Marc Corriveau, general manager of the ABB Measurement & Analytics’ Analyzer factory in Quebec City.

Project manager Laurent Drissen explained that SITELLE is the logical continuation of SpIOMM project, an imaging spectrometer prototype developed jointly by Université Laval and ABB, which for nearly 10 years has been one of the most used instruments at the Mont-Mégantic Observatory at the entrance of the National Park of Mont-Mégantic in Notre-Dame-des-Bois, Quebec, within the framework of masters and doctorate projects. He added, “I would like to acknowledge the priceless contribution of a dozen students, both for the design of data analysis software and for the development of the observation methods and testing phases, as well as the outstanding support of management and CFHT staff. SITELLE is an exceptional instrument which I believe will make its mark in the history of astronomical instrumentation.”

Building SITELLE also involved the expertise of several companies in the Quebec region, particularly in the areas of carbon fibre moulding, precision machining, and fibre laser source. Université de Montréal, partner of Université Laval in the Centre for Research in Astrophysics of Québec (CRAQ), also provided opto-mechanical expertise for the project. Building SITELLE was also supported by grants from the federal and provincial governments through the Canada Foundation for Innovation (CFI) program.