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Timing is everything
The Palomar-Quest Survey's emphasis on time variability is an important advance for observational astronomy. It requires imaging a large region of the sky repeatedly over the course of months or years while scanning for changes. This in turn requires using a Schmidt telescope, which has a much wider field of view than most telescopes in use today--including Hubble. The 48-inch Samuel Oschin telescope at Palomar is the second-largest Schmidt telescope in the world.
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Side view of the camera as mounted inside the Samuel Oschin Schmidt Telescope at Palomar. |
"People have studied quasar variability before," says Brunner. "But it's usually to monitor a small number of sources for 10-20 years, or to match new data against much older data. Actually going out and surveying significant fractions of the entire sky--a tenth, a fifth, a quarter--and doing it over and over again for a number of years--that's really a new thing."
Brunner says that the process has worked well from the very first data transmission in April of this year. "We're an invisible part of the infrastructure now," he says. And for PQS, invisibility--running smoothly and uneventfully without a hitch--is crucial. "If you want to catch things which are changing in time," says Baltay, "you don't have the leisure of waiting months and months before you process your data, because by that time the thing is gone." He hopes that in the future data transmission can be speeded up even more dramatically through automation, so that, for example, raw data received at 8:10 p.m. can be sent, processed, and archived 20 minutes later.
Using data from the new camera that was processed at Caltech led, for example, to the discovery in November 2003 of the planetoid Sedna, the most distant solar system object ever observed and the largest Kuiper Belt object after Pluto. More recently, Palomar-Quest Survey data processed at NCSA yielded a potentially valuable cosmological discovery: a relatively rare, redshift 4.07 quasar that was discovered in follow-up, time-critical observations by a team led by Caltech professor George Djorgovski. While Brunner points out that more distant quasars have been identified, he believes that the real value of the find is that it demonstrates what PQS can do: "It's proof that we're going to be able to systematically find high redshift quasars using the Palomar-Quest Survey.
