University of Wisconsin-Madison Physical Sciences Lab

Learn More: WHAM

[WHAM color photo]

In 1995 PSL built the WHAM telescope for the UW-Madison Space Physics Program. The telescope is designed to map the density and motion of ionized hydrogen in the galaxy. Because it is significantly larger than the previous telescope, WHAM was able to map the entire northern hemisphere within three years. PSL designed and built the siderostat, which includes the light-collection casing, the mechanics and electronics for rotation, and the software allowing the siderostat to interact with the control panel. The siderostat stands almost 4.3 meters (14 feet) high and weighs about 5 tons. The siderostat rotates around the vertical and horizontal axes, allowing the telescope to map north to south and from horizon to horizon across the sky. The interior is painted a diffuse black, with special low outgassing paint to minimize contamination of optics surfaces. The exterior is painted with special low absorptance white paint to minimize solar heat gain during daylight hours. The siderostat is designed to survive up to 200 kilometers per hour (125 miles per hour) winds.

After operation at Pine Bluff, Wisconsin for a year of testing and software development, WHAM was moved on November 19, 1996 to Kitt Peak, Arizona. After the H-alpha survey, which mapped for the first time the distribution and radial velocities of the ionized interstellar hydrogen across the sky, WHAM began more comprehensive studies of selected portions of the sky (based on what is seen in the survey). These studies (lasting several years) involved observations of even fainter emission lines from trace ions, such as S+ and N+, to probe the physical conditions in the gas (e.g., temperatures and ionization states).

WHAM Survey Picture

The status of WHAM and research conducted with it was described in June 2006 in an email by Ron Reynolds (reproduced on this website by his permission).

In 2006 the UW Astronomy Department was funded by the National Science Foundation to upgrade some of the WHAM hardware and then relocate WHAM to the Cerro Tololo Interamerican Observatory in Chile. This enabled WHAM to reach portions of the southern sky (the black region in the image below) not accessible from the Kitt Peak location and complete the all-sky survey for the H-Alpha spectral line. WHAM returned to Wisconsin in April 2008 for maintenance, upgrade & preparation for shipping to Chile. In March 2009 it was uncrated and setup for operation in Chile. As of January 2011 the gap had been approximately 90% filled.

Visit the WHAM website at the UW Madison Astronomy Dept.