CATAC Update on the Thirty Meter Telescope

By / par Michael Balogh (CATAC Chair)
(Cassiopeia – Winter / hivers 2018)

TMT Science Forum

The sixth TMT Science Forum was held in Pasadena, Dec 10-12. The agenda and participant list are available here. It was great to see so many Canadian researchers attending, and actively participating in the discussions. It was especially encouraging to see all the excellent science being done by our postdocs and graduate students, and their ambitions for more great things with TMT. Some of them also participated in the TMT Early Career Workshop the week before the Forum, where they were immersed in a start-to-finish instrument design experience.

A major focus of discussion was the US preparation for a preconstruction proposal to the NSF, largely to support instrumentation development, and preparation for the US Decadal survey Astro2020. Much of this work involves developing Key Science Programs, designed to make use of potential US access to both TMT and GMT. While this is a US-focused exercise, many of these Key Science Programs build on work that has already been done within the TMT community, by the International Science Definition Teams.

Compelling science cases were presented for several future instrument concepts, including multi-object NIR spectroscopy, high-contrast imaging and high-resolution spectroscopy. Discussion of the relative priorities of these concepts was an important agenda item for the SAC meeting that immediately followed the forum. Early in January, CATAC will be engaging with the Canadian community to develop a clear picture of where our priorities lie.

While this was the last Forum funded through the cooperative agreement with NSF that sparked the meetings, many people expressed the opinion that they should continue. While it is likely the next meeting will be held in China, I hope that we will consider hosting one in Canada perhaps the year after that.


The big news in the past months has been the positive ruling in both contested cases before the Hawai’i Supreme Court. First, in August, the Court ruled unanimously in favour of TMT on the issue of the sublease. Then, at the end of October, the Court delivered a 4-1 decision to uphold the Conservation District Use Permit issued to TMT by the Land Board. This is welcome news, that now gives TMT the legal right to restart construction. While it is expected that there will still be protests, the latest polls show strong support for TMT among Hawaiians. We are therefore hopeful that construction can begin soon, amid a welcoming environment in Hawai’i.

First Light Instrumentation

The SAC met in October to recommend a design choice for the Wide Field Optical Spectrograph, one of two first light instruments on the TMT. CATAC’s public report on the three designs under consideration was made available to SAC members. The SAC recommended that the project pursue the multi-slit imaging spectrograph design (Xchange), which was also the design preferred by CATAC. This concept will be the baseline for further development.

A conceptual design review of an adaptive secondary mirror (AM2) was held in October, and no show-stoppers were identified. However, there are risks associated with deploying an AM2 at first light, and it complicates commissioning. While an AM2 could have a big impact on future instruments, simplifying their design, it will not significantly affect WFOS or IRIS. Therefore, while there is interest in this being an early capability, it may not be necessary to push for it to be ready at first light.

Recent and Upcoming Meetings and Events

  • US-ELTP Splinter session at AAS, Seattle on Monday Jan 7, 2019
  • Conference, “Extremely Big Eyes on the Early Universe”, UCLA Jan 28-Feb 1, 2019
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