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Comet 46P Wirtenan - visibility

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Andrew Paterson's picture
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Last seen: 1 week 23 hours ago
Joined: 02/04/2016 - 09:23
Comet 46P Wirtenan - visibility

There are some great images of this comet being posted.I unfortunately didn't look when it was at its closest but have tried finding it over the last two nights when it has been clear and moonless near o UMA.  I have however totally failed to see it either with 10x50 binoculars or with an 8in SCT.  Is this because I am looking in the wrong place or that its surface brightness is so low that it is not visible with the equipment I have? I can pick up M33 in Triangulum fairly easily with the binoculars which is another large low surface luminosity object.

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Last seen: 2 hours 36 min ago
Joined: 10/03/2014 - 09:25
46P

It should still be visible in 10 x 50's if your skies are good enough to show M33 in same. I could still see it in my 7 x 50's a few nights ago. Have you got the latest coordinates? It's 1 degree 16 mins to the right (NE)  of Omicrom at 10pm tonight.

Andrew

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46P

I saw it a couple of nights ago as a hazy patch with 10x42IS binicoulars and it was not hard. It was right where SkySafari said it should be. I suspect that unless you were using a very wide field eyepiece with the C8 you may have seen through it.

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Visual obs

I agree with Andrew and Owen. For me, I found that once it had moved over the north sea into dark skies, I could star hop to it using binos.  It has a very diffuse appearance which responds to averted vision. I have also used GOTO with my C8 and looked at it with my Televue 32mm plossl. Not an impressive object visually, but there.

Peter Anderson's picture
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Visibility of Comet Wirtanen

Like many others I have not seen it. I tried several times in early December - I am 27.5deg South and 153 deg East, but did not see it and then the clouds rolled in. However, though in the hills, I live only 10km from the centre of a major city to my east and the sky is not dark. (At zenith mv 5.3 to 5.4 at best.)  I had simply tried in the area using binoculars and 8X50 finder scope and nothing 'popped out'.  People well in the country- and here I am talking 200km away, saw it as a faint fuzz blob with a brighter core and shorter focus lenses recorded it as such.

Now, I am not a great fan of comets though there have been some spectacular ones. Ikeya Seki in 1965, Bennett in 1970, Halley maybe during the Total Lunar Eclipse on 24th April 1986, Hyakutake in 1996, and so on. Though it hung around for a while I wasn't impressed by Hale-Bopp, though McNaught in January 2007 was great.  Now there were many others in this period, some I missed due to cloud, but no others 'seared' into my mind.

My experience in looking for comets is to deduct around 2 to 3 magnitudes from the stated brightness and then start looking, since much of the brightness is the fuzzy surrounding coma and a combined magnitude is the one given.

This is particularly so with comets approaching close to the Earth because, being closer the coma is so much more extended. IRAS Araki Alcock in 1983 as it travelled north to south in the evening sky, looked like a fuzzy ill defined tennis ball several degrees across - just a large fuzz blob with no discernable nucleus.  Very disappointing!

The diminutive but very active nucleus of Wirtanen only grew a narrow and faint tail but given the geometry (it was effectively at 'opposition' when closest), the tail would have been largely obscured by the fuzzy diffuse coma directly in front from our line of sight.

Anyway, for me, clouds again intervened around the time of closest approach. (You see our summer has much more rain and cloud.)
So I didn't see Wirtanen either, but I don't think I missed much.

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Diffuse comets are difficult to see

As others have said 46P/Wirtanen is exactly where the orbit says it should be but diffuse comets are much more difficult to see than their magnitudes would suggest. Even though this one got to 4th magnitude at its brightest the light was spread over an area several times that of the Moon. I did see it a few times from my light polluted garden in Chelmsford using 11x80 bins but it wasn't easy. Other people at dark sites did get a much better view. With these diffuse comets it is usually better to use binoculars than a telescope.

Peter Carson's picture
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46P redefined observing habits

Even at its brightest I had great difficulty in seeing 46P from my light polluted back garden with binoculars or a telescope, but it was easy to image. There was one time when I ventured to a reasonably dark site and could easily see it naked eye only to come home and then couldn’t find it with binoculars.

46P was a really strange comet that required unconventional observing techniques.