Issue 8 • February, 2007
Thirty Meter Telescope

Project Manager's Corner: Scheduling TMT I
  Gary Sanders

Last month I discussed adjustments to the design of TMT and to its estimated cost. I described our progress into the last phase of TMT design. By May 2008 we plan to complete the site-independent Preliminary Design of TMT. This means that we will have fully defined the design that we intend to build and that this design can be shown to meet the design requirements. Following that phase, we will have selected the TMT site and will proceed to complete site-specific elements of the design, such as different foundations for different local geology. Final design, where detailed construction documents are completed for industry, follows and this initiates construction.


Science Nugget—Observatory Operations: Setting the Stage
  David Silva

As described elsewhere in this Newscast, the TMT project is already running small observatories every night on five different mountaintops. These observatories operate robotically, picking out target stars under automated control, collecting data and relaying the information to local and remote archives. When systems fail or degrade, TMT personnel must journey, often on short notice, over long distances to make repairs or adjustments. This continuous, night-after-night operation must meet demanding reliability standards and produce scientifically reliable data, suitable for any reputable scientific journal. The figure shows an interesting byproduct of this program—an image of Comet McNaught caught by one of our all-sky cameras. (For more on site testing, see the Focus On article below. For more on the all sky camera see the July Newscast.) This spectacular naked eye comet was the toast of the Southern Hemisphere in January.


Technology Nugget—APS
  Gary Chanan

The Alignment and Phasing System, or APS, is the TMT instrument that is responsible for the precision optical alignment of the telescope. Perhaps its most challenging task is the proper phasing of the segments: in order for the TMT to achieve its ultimate theoretical resolution, the 492 segments of its primary mirror must form a continuous optical surface, with the steps between adjacent segments no larger than 6 nanometers (nm) high, or less than one one-hundred-millionth of a segment diameter. By contrast, a poorly phased TMT would have an angular resolution no better than that of a 1.2 meter telescope!


Q & A with George Angeli

George Angeli is the Head of Systems Engineering for the TMT project. He has been involved in the design of Extremely Large Telescopes since 2001. Before formally joining the project he was working on the Giant Segmented Mirror Telescope (GSMT) at NOAO and chaired the Integrated Modeling Working Group for the collaborative efforts of CELT, GSMT, and VLOT.

George sat down recently for an interview with Doug Isbell to talk about the systems engineering challenges of the TMT project.

Download George Angeli Interview
[9:29 min. 8.6 MB MP3]

Focus On—Deployment of the IRMA Infrared Water Vapor Radiometers
  Matthias Schoeck

The higher you go, the drier it gets. That is the rule of thumb concerning the average amount of precipitable water vapor (PWV) above an astronomical site. It works pretty well as a guideline, but there are many aspects of PWV that are of interest for TMT in a more quantitative way. How often is the PWV content of the atmosphere above the site lower than a certain value? What are the conditions one gets during the best 10% of the time? Are there diurnal or seasonal patterns that are specific to a site? And so on. The answers to these questions will not only affect site selection, but might also determine certain TMT operations strategies. For example, if the PWV is always high during a certain time of the year, you would not schedule mid infrared observations for that time. Operation of a PWV monitor on the TMT candidate sites was therefore always considered highly desirable.


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TMT is supported in the United States by the Gordon and Betty Moore Foundation and the US National Science Foundation. Canadian funding is provided by the Canada Foundation for Innovation, the Ontario Ministry of Research and Innovation, the National Research Council of Canada, the Natural Sciences and Engineering Research Council, and the British Columbia Knowledge Development Fund.

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