Greenland Telescope

The Telescope

The Greenland Telescope is based on the ALMA North America prototype antenna built by Vertex AG. The antenna was completely refurbished and rebuilt for operation in the colder and somewhat lower altitude conditions found at Summit Station, Greenland. It is a 12m diameter Cassegrain system with a primary F/d ratio of 0.4 and maximum field of view of approximately 15 arcmin. A nutator will be used to chop the secondary mirror for single dish observations.

The telescope is installed and operating at the Thule Air Base as of January, 2018. Initial installation and alignment of the panels achieved 50µm  RMS surface error as measured by a laser tracking system. The surface of the antenna will be set using near-field holography later in 2018. Noting that, a 16µm  RMS surface error has already been achieved on this antenna during the ALMA prototype testing. With the additional upcoming holography runs we believe that this antenna should yield reach the 12µm  RMS surface currently being achieved on ALMA production antennas.   Blind pointing accuracy of 2"  will be achieved across the whole sky, with an  offset  pointing accuracy of  1" .

Philippe Raffin, ASIAA Radio Antenna Engineer, authored an excellent SPIE paper in 2016 summarizing the retrofit status: Raffin, P., et al. The Greenland Telescope: Antenna Status and Future Plan, Proc. SPIE Edinburgh, Vol. 9906-29 (2016)

Greenland Telescope

The Greenland Telescope antenna prior to disassembly at the VLA site in Socorro, New Mexico in 2010