Observing Ison at perihelion

So far Comet ISON has spent November sinking ever lower in the east before sunrise as it heads toward the Sun. Ironically, the comet should brighten greatly as it disappears into the Sun's glare.

But you might have a long shot at seeing the comet at its very brightest, as it pulls a hairpin turn around the Sun on Thanksgiving Day, November 28th. Comet ISON will be physically closest to the Sun that day around 19^h Universal Time. It will appear within one Sun diameter of the Sun's edge from about 17^hto 20^h UT. 

Use the chart to determine where the comet is with respect to the Sun. The comet's position is indicated every 12 hours (in Universal Time; adjust to your time zone accordingly), and celestial north is up.

As the chart shows, during its perihelion the comet swings around the Sun in a counterclockwise direction. It's due south of the Sun at 17:30 UT, very close to its southeast at 18:30 UT, due east at 19:20 UT, and farther northeast for several hours thereafter.

From Comet ISON's point of view, the Sun will be

enormous during its closest approach, filling the comet's sky and broiling its surface to a temperature of about 2,700° C (4,900° F). That's almost hot enough to melt iron, not to mention ice! The comet should peak in brightness from around perihelion until perhaps a few hours after.

Will it be detectable then? If you block out the Sun's disk very cautiously and carefully with no momentary lapses — put the Sun behind a chimney or lamp post, not your wavering finger — you might possibly detect the comet's fuzzy pinpoint of a head with the unaided eye if the air is very clear. Do not attempt this with binoculars or a telescope!

 

Block the Sun's disk very cautiously using a chimney or lamp post (pictured here) — not your wavering finger — on November 28th, and you just might glimpse the comet's fuzzy-pinpoint head with the unaided eye. Do not attempt this with binoculars or a telescope!

S&T: Alan MacRobert

 

 

http://www.skyandtelescope.com/observing/highlights/Spot-Comet-ISON-at-Perihelion-233011581.html