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PostPosted: January 4th, 2017, 6:41 pm 
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Joined: October 12th, 2009, 3:28 pm
Posts: 4117
Location: Baton Rouge, LA
This magnitude estimates for this object are interesting enough to note, and this may be the first of a number of moderately bright comets that may greet the 2017 skies above Baton Rouge! The last viewing report sent to Harvard's "International Comet Quarterly" was on 10 December from H. Abe in Japan, who used a 0.26-meter reflector and CCD to estimate that 45P had a magnitude of 10.9. It is far from magnitude 10 in January and February!

45P was discovered by Minuru Honda on 3 December 1948. It has a nucleus almost one kilometer across and an orbital period of about 5.3 years. Most of its visits to the inner Solar System have been observed, although it was missed in 1959 and 1985.

So what can we expect through a binocular or telescope? Well, Starry Night Pro Plus generates some...okay magnitudes, stating 45P right now is magnitude 7.1, but fading. Here's what I get from Starry Night...
7 January = magnitude 7.1
10 January = magnitude 7.2
13 January = magnitude 7.3
16 January = magnitude 7.5
19 January = magnitude 7.6
22 January = magnitude 7.8
25 and 28 January = magnitude 7.9
31 January = magnitude 8.0
3, 6 and 9 February = magnitude 7.8

These, however, are the dimmer estimates. Chris Peat has a "last observed magnitude" of 7.0. Seiichi Yoshida also gives the current mag as 7.0; he says 45P will brighten to 6.9 by Saturday. Sky & Telescope is guessing that in February 45P may be as bright as 6.5; I found no mention of 45P at Astronomy's website.

These are the estimates from Greg Crinklaw...
4 January = 7.1
8 January = 7.2
15 January = 7.3
18 January = 7.4
21 January = 7.5
24 January = 7.6
26 January = 7.7
31 January = 7.9

Now here's the catch in all this...45P is drastically low on the horizon tonight. When darkness comes at 6:43pm CST it will be nine degrees above the horizon (basically to Venus' lower right). Baton Rougeans really won't get a chance to even attempt a viewing until 5 February!

Historical Background for 45P:
http://www.cometography.com/pcomets/045p.html

More information:
http://www.aerith.net/comet/catalog/0045P/2016.html
http://www.skyandtelescope.com/wp-content/uploads/WEB_Comet45p_DecJan.pdf


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