Categorized | Sci-Tech

TMT releases atmospheric data online


The Thirty Meter Telescope Project (TMT) is launching a new database containing five years of atmospheric data from the telescope’s initial five candidates sites: Cerro Tolar, Cerro Armazones, and Cerro Tolonchar, Chile; San Pedro Martir, Mexico; and Mauna Kea, Hawaii, the site selected for TMT.

A Web site containing the entire dataset, the largest of its kind, is available free-of-charge to the public.

“TMT believes that this dataset will be of great interest to the site testing community and astronomers in general,” said Matthias Schoeck, TMT’s Image Quality Scientist. “Whether it is because they are interested in the sites themselves or as input for simulations or data analysis, the data will be available to any team looking to build or operate an observatory.”

The breadth and consistency of the dataset will also make it of value to researchers in climatology, boundary layer physics, aeronautics, and satellite studies, explained Schoeck.

The new database includes accurate and long-term measurements of virtually every atmospheric feature that might affect the performance of the telescope, including turbulence strength, temperature, barometric pressure, wind speed and direction, humidity, atmospheric water vapor content, solar irradiance, ground heat transfer, dust levels, and cloud cover.

An essential element of the TMT site testing campaign was the deployment of identical equipment at all five sites. TMT also took great care in cross calibrating its instruments. As a result, the data can be compared quantitatively across all the sites with high confidence. The data also cover long enough time periods to be representative for the sites, barring major changes in local or global climate.

The database will contain the entire body of work from the site testing campaign in ASCII format; it also will include basic graphing tools. Users will be able to select and compare data from the various sites, data ranges, time periods, instruments, and other parameters.

The data will not carry any restriction, apart from a standard acknowledgment guideline.

Funding for the site testing campaign, led jointly by TMT and the Association of Universities for Research in Astronomy (AURA), came from the TMT project and the National Science Foundation.

In addition to Schoeck, members of the TMT/AURA core site testing team include Tony Travouillon, TMT’s Environment Control Scientist; Warren Skidmore, TMT’s Telescope Research Engineer; Reed Riddle, now at Caltech Optical Observatories; and Sebastian Els, now working for the Gaia satellite project in Madrid, Spain. In total, almost 100 individuals at many different institutions around the world contributed to the success of the TMT site testing work.

Using the results of the site testing campaign and other factors, the board of directors of the TMT Observatory Corporation selected Mauna Kea as the preferred site for the telescope in July 2009.

The TMT project has completed its $77 million design development phase with primary financial support of $50 million from the Gordon and Betty Moore Foundation and $22 million from Canada. The project has now entered the early construction phase thanks to an additional $200 million pledge from the Gordon and Betty Moore Foundation.

Caltech and the University of California have agreed to raise matching funds of $50 million to bring the construction total to $300 million, and the Canadian partners propose to supply the enclosure, the telescope structure, and the first light adaptive optics.

The TMT project is an international partnership among the California Institute of Technology, the University of California, and the Association of Canadian Universities for Research in Astronomy. The National Astronomical Observatory of Japan (NAOJ) joined TMT as a Collaborating Institution in 2008. The National Astronomical Observatories of the Chinese Academy of Sciences (NAOC) joined TMT as an Observer in 2009.

To access the archive, visit

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