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Old 16-12-2018, 10:02 AM
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mental4astro (Alexander)
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mental4astro is offline
 
Join Date: Jun 2008
Location: sydney, australia
Posts: 4,797
Photo opportunity tonight - Comet & Pleiades conjuntion

Hi all,

The spate of nice conjunctions keeps on happening. Though this time I need to apologize for the short notice of this one,

For those of you not aware, Comet 46P/Wirtanen comes within a tick of 3.5 of the Pleiades tonight. It's closest approach is around 12:30, Sydney time, but the moon is still an hour from setting. Of course the moon is gone an hour later, but the pair will also be a little lower in the sky too. The pic below is a screen shot from Sky Safari showing the approx closest approach of the pair, from Sydney. Time & celestial position of course depends on your own location. The comet also reaches perihelion around now too.

BIG coma the comet has too. I saw it last Saturday night and I estimated it was over 1 in size - twice the diameter of the full Moon.

On a side note, I wonder if 46P/Wirtanen's short tail is due to foreshortening rather than it not being there. It's trajectory brings it very close to us, and the relatively shallow angle between trajectory and proper motion with respects to us means we see the comet approach us nearly head-on.

I've got my fingers crossed for a clear couple of hours around midnight tonight. May head up Killara/Mona Vale way here in Sydney as I then avoid looking through the glare of the CBD from my place.

Tomorrow night 46P/Wirtanen is close to 6 away from the Pleiades.

Happy hunting,

Alex.
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