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COMET -  C/2014 Q2 Lovejoy

Relative motion of comet C/2014-Q2 Lovejoy over half an hour. 

Shot from the city with a 60mm refractor f/6.2, 7D and EQ6. Individual frames are 60" exposures at ISO 800. Played with the RAW files a bit, then turned them into jpegs to make this.

You will notice dead pixels, drift, noise and strange wobbling.
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2015-01-24
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COMET - C/2014-Q2 Lovejoy

Not visible to the naked eye from the city but nice and bright through the camera's finder at 80mm and f/6.2.

Easy to spot a few degrees below the Pleiades.
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COMET - 17P Holmes

Flashback 2007: the outburst of 17P-Holmes

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COMET - N3 Lulin

The photo shows the comet's apparent movement in the sky over a period of 1h. DSS (Deep Sky Stacker) allows you to align either on the background stars, or on the comet's nucleus. having aligned on the stars, this photo gives you the line corresponding to the path of the comet over the period of time corresponding to exposure.
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COMET - N3 Lulin

The white balance is off, but one gets an idea of the general shape of the object - with a little good will you can see a hint of a tail as well.
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COMET - N3 Lulin

Photoshop fun - you can see the tail... sort of.
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COMET - N3 Lulin

Image processing shows in fake colours details of the comet's structure.
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COMET - C/2007 N3 Lulin

Discovered: 2007
Epoch: December 6, 2008
Aphelion: 2400 AU
Perihelion: 1.2122 AU
Semi-major axis: 1200 AU
Eccentricity: 0,99998
Orbital period: 42 000
Inclination: 178,37°
Last perihelion: January 2009
Next perihelion: unknown

N3 Lulin is a non-periodic comet. It reached perigee and a maximum magnitude of 5 in February 2009 at 0.411 AU from Earth (182 million km)

A strange phenomenon occurred with this comet - it lost its tail. This is thought to have been caused by a magnetic disturbance in the solar wind hitting the comet. This has happened before with comet Encke in 2007.
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COMET - 17P Holmes

And the blue one in negative - does show some structure.
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COMET - 17P Holmes

The 2007 outburst


Holmes usually shined at an obscure mag 17 before brightening up to mag 2.8 in 40 hours or so (October 23 to 24), making it visible to the naked eye in Perseus: observers easily distinguished a fuzz in the sky even in heavily light-polluted skies.

Chance made it that the outburst coincided with opposition, making it even more spectacular. The position of the comet was such that observers on Earth were looking down its tail - its appearance was somewhat different of the "blob-and-tail" image one associates with comets. It was nicknamed the jellyfish comet because of the peculiar shape long exposures showed (NOT visible in my images here).
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