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Ceph and Cass

My take on 2011 L4 PANSTARRS


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I had forgotten all about this comet, but having spent hours on one two years ago at Kelling with dire results, I was keen to try again, and thought it might be just the target for my new Atik 460ex OSC camera to cut its teeth on.

The motion and direction of the comet over 1 hour and 18 minutes is indicated by the faint line through the core.

26 x 3 mins, Skywatcher Esprit 460ex Colour. Stacked in DSS.

Thanks for looking!

Tim

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To be quite blunt I don't understand comets at all, I don't know what an anti tail is, and I don't get how the tails can be anywhere except behind the head of the comet :s

I was under the impression the anti-tail is the long extended thing exiting top left?

DSS stacks both on the comet and the stars, and has taken a frame mid way along the movement as a reference frame by the look of it.

Here's a version stacked on the comet alone.

Cheers

Tim

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Ah, I see, confusion rules supreme :)

The faint line I mentioned is this one, right through the heart of the comet. It's just the path of the comet, although I dont know if it is going left to right or vice versa.

post-1391-0-42373300-1369869182_thumb.jp

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The anatomy of your first image is that the bright bit is the nucleus (you knew that already though!), the fuzzy bit to the lower right of the nucleus is the dust tail while the long thin line that runs from the nucleus towards the upper-left corner is the orbital plane spike or, when it's directly opposite the dust tail, the anti-tail. The line you have running through the nucleus sort of at right angles to the anti-tail, I assume is an artefact of whatever you've done processing wise and shows, as you say, the motion of the nucleus over the capture session.

The orbital plane spike is caused by dust particles ejected from the nucleus that move away from nucleus but spread around the comets orbit. These are typically too large to be affected by radiation pressure and so are not 'blown' back to appear to emanate from the nucleus in the opposite direction to the Sun. These particles will be ejected from the nucleus with all sorts of force vectors so some move slightly further away from the Sun than the nucleus, some slightly closer. This, and their initial ejection vectors, changes their orbital period and over time they spread around the orbit in a stream with tangible width.

Imagine a sheet of glass with an extremely fine sprinkling of talc on it. If you look through the glass as you would look through, say, a window, the dusting wouldn't be that obvious. However, if you tilt the glass so that you're looking at it edge on, the talc particles are seen grouped together and suddenly stand out as a line.

In the case of comet C/2011 L4 PANSTARRS, Earth passed through the orbital plane of the comet on 27 May. This emulates looking through the glass edge on and the normally rather scattered dust particles appear grouped together. As they reflect the light from the Sun, from Earth they appear as a distinct line indicating where the orbit of the comet lies.

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Fantastic image of this Tim, lovely background star field and the incredibly long/fine tail makes a great composition. Nice result for the 460ex and especially the processing dealing with the bright sky/full moon.

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Thanks. If I'd known about the length of the tail then I'd have used a camera lens on it I think, have got the Geoptik thingy somewhere to do just that :) Maybe tomorrow night, should be less moon input too.

Getting the comet to stack in DSS was tedious, but the result was better than the one from Pixinsight. This is likely down to my Frank Spencer PI skills though :p

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Getting the comet to stack in DSS was tedious, but the result was better than the one from Pixinsight. This is likely down to my Frank Spencer PI skills though :p

Ooh Betty - that's certainly no whoopsie! Perhaps being a little over modest there, but I'll look forward to the sequel shot.

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