The Pasadena-based Thirty Meter Telescope Board Endorses Design for Key Instrument

Published : Wednesday, November 14, 2018 | 5:54 PM

The Pasadena-based Thirty Meter Telescope International Observatory (TIO) has endorsed a recommendation from its Science Advisory Committee to select a more conventional slit-mask-based imaging spectrograph design for the telescope’s Wide Field Optical Spectrograph (WFOS), its second first-light instrument.

First light refers to the first use of a telescope to take an astronomical image after construction. The Wide Field Optical Spectrograph concept follows the Infrared Imaging Spectrograph (IRIS), which integrates a field spectrograph (an instrument that separates light by its wavelengths) and an imaging camera. While WFOS is currently under conceptual design review, IRIS is now under the second phase of its preliminary design review.

Members of the TIO’s Science Advisory Committee met in Pasadena in October to talk about the observatory’s science requirements and its suite of instruments and review evaluation reports about the two concept options for the Spectograph: a fiber-based design and a slit-mask design.

Once installed and operating, Wide Field Optical Spectrographs will serve teams of researchers in a broad range of scientific interests, including the study of the distribution and nature of dark matter in the universe, as well as the composition of high-redshift galaxies (galaxies that appear to be moving away from the observer, as opposed to blueshift, which appears to be moving closer) and the physics of supernovae and gamma-ray burst events.

A TIO statement said the decision to select a slit-mask concept for its first-light multi-object spectrograph was mainly driven by the desire to emphasize the design’s customizable capabilities, which can be fine-tuned by each observer for specific science goals. The slit-mask design will provide excellent throughput and imaging over an approximate 25 square-arcminutes field-of-view. Arcminutes are a unit of angular measure used to figure out distances on the sky.

The Wide Field Optical Spectrograph (is being readied for installation on the TMT by the late 2020s.

The Science Advisory Committee meeting also covered discussions about the next-generation instrument concepts that were submitted in response to its call for white papers, the TMT statement said. The SAC also discussed the organization of the upcoming TMT Science Forum “Breakthrough Science with the Thirty Meter Telescope” to be held in Pasadena in December.

The TIO is designing and developing the Thirty Meter Telescope project. The organization is a non-profit international partnership among Caltech, the University of California, the National Institutes of Natural Sciences of Japan, the National Astronomical Observatories of the Chinese Academy of Sciences, the Department of Science and Technology of India, and the National Research Council (Canada).

The organization will also run the TMT operations once the telescope is completed.

For updates on the TMT project and more information on the managing organization, visit









blog comments powered by Disqus