Lowell Observatory astronomer Matt Knight had good news this morning for the team assembled by NASA on Kitt Peak to observe Comet ISON:

"ISON has brightened by a factor of four in the last 12 hours or so," Knight said.

Knight, of NASA's Comet ISON Observing Campaign, had been up early, using data from the NASA/European SOHO satellite to produce the latest assessment of ISON's brightness.

"It's sure behaving like a sun-grazing comet," said Carey Lisse, a member of the team from Johns Hopkins University Applied Physics Lab.

ISON, which makes it closest approach to the sun on Thanksgiving Day, was expected to brighten as it approached, but in the last couple days it had dimmed, leading Knight to worry that it might not survive its passage around the sun.

Wednesday morning he was much more optimistic about the comet's chances of emerging intact and bright enough to be seen by the naked eye when it gains separation from the sun in 10 days or so.

Knight said the comet is now bright enough to be seen by the McMath-Pierce Solar Telescope, where the group is gathered this week. For the last couple days it had been too faint to stand out form the glare of the sun.

The only thing standing in the way this morning was a band of clouds that stretched across the horizon atop Kitt Peak.