Yale and Indiana University Collaborate on Outfitting Telescope At Palomar with New and Powerful Camera
Yale researchers working with colleagues at Indiana University have added a giant electronic camera to a veteran telescope at Palomar observatory that will be used to look for distant galaxies, supernovae, asteroids and other objects in the sky.
“We are quite excited by the new data we are starting to obtain from the Palomar observatory with the new QUEST (Quasar Equatorial Survey Team) camera,” said Charles Baltay, professor of physics and astronomy at Yale University. Baltay initiated and led the QUEST project.
The QUEST camera was attached to the 48-inch Oschin telescope at the Palomar Mountain observatory in California. In the past, astronomers using the Oschin telescope loaded glass photographic plates into the telescope to capture images in the sky. The telescope became fully automated in 2001 when an electronic camera known as the Near-Earth Asteroid Tracker (NEAT) was installed. The camera employed a large electronic chip known as a “charged coupled device,” (CCD) to detect light. The retrofit was very successful. During its tenure on Palomar, the NEAT team discovered 189 near-Earth asteroids and 20 comets, and other large members of the Kuiper Belt.
The new QUEST camera is yet another leap forward. The camera has an array of 112 CCDs, or the equivalent of a 161-megapixel camera, making it one of the largest CCD arrays ever assembled. A digital camera for personal use usually has about four megapixels.
Although the QUEST camera was designed for the Oschin telescope, the Oschin had to undergo serious changes to accommodate it. The telescope has a 48-inch piece of glass, known as a corrector plate that sits at its skyward end. This was removed so that the effective length of the entire telescope could be slightly reduced. The corrector plate was then reinstalled in a new housing at the front end of the telescope.
The process, under the oversight of Richard Ellis, director of the Palomar observatory, was guided by Robert Thicksten and Hal Petrie of the California Institute of Technology. Mark Gebhard of Indiana University, William Emmet, senior mechanical engineer, and David Rabinowitz, a research scientist in physics, both from Yale, constructed the camera at Yale and Indiana and handled the delicate installation of the camera and its electronics inside the telescope. Philip Childress, foreman of the UI physics shop and Thomas Hurteau of the Yale Gibbs shop were instrumental in the fabrication, assembly, testing and modification of the camera.
The camera’s readout electronics were constructed by the physics department at Indiana University at Bloomington under the direction of James Musser. The camera is designed to work in two different modes. One is the more familiar method: point the telescope and shoot the photo. The second mode works in what is known as drift scan. In the drift scan mode the telescope is pointed at the sky but does not move to counteract the rotation of the earth. Instead, various objects in the sky gradually drift across the field of view at the same rate as the computer reads out the CCDs, producing photographs that are long strips of the sky.
The QUEST team used a similar camera to find the distant, frozen planet known as Huya. Huya is about one quarter the size of the planet Pluto and one of the biggest objects to be found in our solar system since Pluto was discovered in 1930. It resides in the Kuiper Belt located beyond Neptune.
In addition to looking for more Kuiper Belt objects, astronomers plan to use the camera in the drift scan mode to find objects that might be quasars, which are very bright cores of distant galaxies that are thought to contain supermassive blackholes.