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Telescope Mirror Casting Strengthens Scientific Ties Between U.S. and Mexico
Partners in the binational telescope project plan a synoptic sky survey at infrared wavelengths.
A binational collaboration of astronomers from Mexico and the United States gathered at the University of Arizona Steward Observatory Mirror Laboratory in Tucson today to witness the casting of a 6.5-meter mirror they plan to use in a new infrared survey.
Steward Observatory is casting a 6.5-meter (21.3-foot) "honeycomb" sandwich mirror for a new telescope planned for San Pedro Mártir Observatory in Baja California, Mexico. The telescope is called the San Pedro Mártir Telescope, or SPMT. The telescope represents a major addition to astronomical research capability in the northern hemisphere.
Project partners are Universidad Nacional Autónoma de México, known as UNAM, the University of California, the Instituto Nacional de Astrofìsica, Ôptica y Electrònica, known as INAOE and the UA.
"We are thrilled to help launch this scientific collaboration between UA, the UC and Mexico," said Steward Observatory Director Peter Strittmatter."We expect the partnership to continue long after the survey is completed."
"The UA has a long history of collaborations with Mexico based on synergies among equal partners," said UA College of Science Dean Joaquin Ruiz. "This is a case in point in which the strengths and needs of our Mexican partners perfectly complements our own strengths and needs to make a win-win situation for all. I am glad that the UA will be part of this astronomy venture – a venture that has the promise of greatly increasing our understanding of our universe".
Starting in 2017, the group intends to use the telescope in a dedicated survey to repeatedly image the entire northern sky at infrared wavelengths. The project is called the Synoptic All-Sky Infrared Imaging Survey, or SASIR.
"With this unique combination of telescope size, infrared design and survey strategy, SASIR will help us discover everything from the sun's nearest neighbors to the most distant black holes in the universe," said associate professor Joshua Bloom of the University of California, Berkeley, principal investigator for the SASIR project. "We believe that SASIR will have a tremendous scientific impact across all fields of astronomy."
The estimated cost of the telescope is $200 million, which must still be raised from private sources or from U.S. or Mexican government funding agencies. UNAM is opening a project office in Mexico City next month, and Bloom is optimistic that money for a preliminary design can be raised by the end of the year, with continued funding to enable ground breaking in 2013. The all-sky infrared survey should start in 2017 and last four to five years.
"This is a remarkably strong collaboration between two U.S. and two Mexican research groups," said Jose Guichard, director general of INAOE. "The project, however, still welcomes other partners.""This is a great scientific project which will fully exploit the superb characteristics of the San Pedro Mártir site," said Jose Franco, director of UNAM's National Institute of Astronomy.
Temperatures inside the Mirror Lab's giant rotating furnace reached 1,180 degrees Celsius (2,156 degrees Fahrenheit) this morning.
The 6.5-meter-diameter mold inside the furnace holds 22,500 pounds of E6 low expansion borosilicate glass produced by the Ohara Corporation in Japan.
The glass became liquid at peak temperatures this morning and began flowing between 1,020 alumina-silica hexagonal hollow core boxes inside the tub mold. The hexagonal cores will be removed months from now, after the mirror blank has cooled and lifted off the furnace hearth, leaving the empty cells in the honeycomb glass structure. After cleaning, the finished honeycomb mirror will weigh an estimated 18,500 pounds.The furnace began rotating at high speed yesterday afternoon. The furnace will spin at this speed, 7.4 revolutions per minute, for three days so the mirror achieves the desired focal ratio, f/1.25.
When equipped with the SASIR camera bearing the largest collection of infrared detectors to date, the San Pedro Mártir Telescope will offer an unprecedented view of the infrared night sky, project partners say.