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Prime Time for PANSTARRS
Color image of comet in the twilight sky.
Comet C/2011 L4 PANSTARRS as seen from Mount Dale, Western Australia. The lights on the distant horizon are from the city of Armadale, which is southeast of Perth. Image credit: Astronomy Education Services/Gingin Observatory

March 11, 2013 This week is prime time for observing this comet. (Next opportunity, the year 108,013 +/- a few hundred or thousand years.)

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The comet is very close to the sun so, for safety (and because it is futile to even try), make no observations if the sun has not completely set. Safety first.

Comets are diffuse and faint so temper your expectations. Because the comet will set only a little more than an hour after sunset the sky will still have some brightness which will reduce the contrast. Also, comets are unpredictable as far as how bright they may actually become so we'll all have to wait and see. It is past its closest approach to the sun so it is going to dim.

Find the time of sunset for your location and add about 25 minutes to get to the end of civil twilight. Between March 11 and March 20 civil twilight creeps forward about seven minutes. It is getting darker a little later each day.

At the end of civil twilight the comet will be 8 degrees above the horizon on March 11 moving up to 11 degrees by March 17. That is still pretty low so you will need as unobstructed a view to the west as possible. Trees, buildings, hills, etc. will interfere.

Binoculars are the right tool to use. Telescopes have too small a field of view to see the entire comet but could be used to try to see detail in the coma. Note that a very thin crescent moon will be alongside on Tuesday, March 12. That should make spotting the comet easier.

Although it was pretty low on the horizon on March 11, I was able to spot it with binoculars 35 minutes after sunset due west. The sky was pretty dark, but not completely, and it looked much like the photograph above with a defined coma and nice tail fanning straight up. Now I'll have a better idea of where to look in upcoming days and should be able to find it in a brighter sky.

Seeing a comet is pretty neat so, get out there.

--David M Seidel, NASA Jet Propulsion Laboratory

Color illustration showing the position of comet PANSTARRS
For those in search of comet L4 PANSTARRS, look to the west after sunset in early and mid-March. This graphic shows the comet's expected positions in the sky. Image credit: NASA

Last Updated: 12 March 2013

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