Greenland Telescope

The Site

  Thule Air Base

The Greenland Telescope is currently installed and operating on the Thule Air Base in Greenland. This sea level site, located 750 miles inside the Arctic Circle, has provided a unique opportunity to build and test under arctic conditions while providing crucial access to logistics and support. Water vapor above the site is continuously monitored and, as expected, impacts our ability to use the higher resolution 345 GHz receiver currently installed. We are having great success with the 86 GHz and 230 GHz receivers.

  Summit Station

In order to fully utilize higher resolution 345 GHz receivers, the telescope needs to operate in a drier environment. Few sites in the world offer the type of environment necessary; the summit of the Greenland ice sheet is one of them. This location will also provide a northern most leg of VLBI networks necessary to truly achieve resolutions required to image black holes.

Funding dependent, the Greenland Telescope will be deployed at Summit Station, Greenland. This Arctic research station is funded by the U.S. National Science Foundation (NSF) Office of Polar Programs. It is anticipated that the Greenland Telescope would be constructed 5 miles north of the existing Summit Station Camp at 72°35'N 38°25'W and 3,210 m (10,530 ft) above mean sea level. The site is near the peak of the Greenland ice sheet, near the center of Greenland.

Greenland Summit

Greenland Summit
Figure 01 left, Location of Summit Stations in Greenland. Figure 02 right, calculated atmospheric transmission at Apex Station for median (red) and 10% (blue) winter (Oct-May) conditions.

The NSF has operated the Summit Station since 1989 and weather data exist for almost all of this period. From 2010, twice daily radiosonde observations have been carried out alongside radiometer observations at 22, 60, 90 and 150 GHz as part of the ICECAPS program, while ASIAA has operated a 225 GHz radiometer from August 2011 through 2015. The site is extremely dry during the Oct-May observing season, with a median PWV column of 0.75 mm and PWV below 0.25mm for approximately 10% of this time. Calculated atmospheric transmission is shown in Figure 02. The site is extremely flat and wind speeds are generally low. Winter temperatures reach -65C during the coldest and clearest conditions.

The site has been manned all year round typically with 5 winter-over staff at Summit, working 10 week shifts, with 1 week overlap at each end. With the deployment of the Greenland Telescope this will need to increase to 12 winter over staff, including 5 dedicated to the Greenland Telescope. Summer staffing levels are significantly higher with maintenance and traverse crew, and summer campaign science operations. Access to the site is via ski equipped Air National Guard C130-LC and charter Twin Otter aircraft from Kangerlussuaq and Thule, and by an annual overland sled traverse from Thule. Twin Otter aircraft can reach site year round, but avoid the 2 month period of total darkness in Dec/Jan.