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Comet C/2011 W3 (Lovejoy)

Comet C/2011 W3 (Lovejoy) was discovered as a diffuse object at magnitude 13.0 by Terry Lovejoy, Thornlands, Queensland, Australia on 27 November 2011.  Initially given the designation TLc001 on the NEO Confirmation Page, its orbit was gradually refined and found to match that of a Kreutz sungrazer.  MPEC 2011-X16 issued 2 December 2011 acknowledged that it was indeed a comet, and it was designated C/2011 W3.  NASA called it "The Great Birthday Comet" because it coincided with the 16th anniversary of the launch of the SOHO observatory.
 
Despite firmly expressed predictions that the comet would not (indeed could not) survive perihelion passage, it did, and spectacularly (for a short time at least, before disintegrating and releasing masses of dust!).  Space-based solar observatories turned their imaging resources onto the comet and produced amazing footage of its passage, gathering a wealth of scientific data in the process.  As the comet moved away from the Sun and into Southern Hemisphere dark skies a large and rapidly expanding tail was revealed.  The ion tail was clearly visible and the comet was a spectacular naked-eye sight in dawn skies.  The tail had reached around 38 degrees length by the day after Boxing Day although the surface brightness of the expanding tail was diminishing.  The general consensus was that this was a "Great Comet", some people dubbing it "The Great Christmas Comet of 2011". 
 
As the comet faded the fainter portions of the tail were lost in the brightness of the Milky Way and the tail length seemed to shrink.  But in early new year 2012 the fainter end of the tail was emerging from the Milky Way and by 3 January over 40 degrees was detectable.  The observing time shrank as the waxing Moon moved back and the tail was lost to direct vision, but 20 degrees or so was still being reported as visible in averted vision.  Photography still revealed a faint extension out to 30 degrees and more as moonlight overwhelmed the tail.  As moonlight moved back in evening skies from 13 January 2012, deep widefield photography was once again revealing a very faint tail in excess of 40 degrees long, as far as the brighter starfields of the Milky Way where it was lost.  Fading continued through the latter part of January but the tail remained detectable to around 30 degrees by the end of January, when the comet started to be lost to moonlight.  As moonlight moved back in evening skies towards mid-February, several degrees of extremely faint tail were still detectable photographically.
 
The full extent of the tail was never revealed, due to interference by the bright starfields of the Milky Way.
 
This was the first sungrazer discovered from Earth since C/1970 K1 in early 1970, a gap of almost 42 years in which all sungrazers had been discovered from images taken by space-based observatories.  Both C/2011 W3 and C/1970 K1 were Australian discoveries, reflecting the advantage offered to southern observers in following the Kreutz tracks.
 
 
Ephemeris:
 
 
Seiichi Yoshida's catalogue information:
 
 
The story of the comet:
 
 
Terry Lovejoy's discovery story:
 
 
"The Great Birthday Comet" of 2011, inbound:
 
 
"The Great Birthday Comet" of 2011, survival & outbound:
 
 
Lovejoy survives!
 
 
Some Comets Like It Hot:
 
 
Discover Magazine
article:
 
 
Astronomical Society of Victoria's gallery:
 
 
Rob McNaught's gallery:
 
 
Vello Tabur's gallery:
 
 
Phil Hart's photos:
 
 
Alex Cherney's gallery:
 
 
Russell Cockman's gallery:
 
 
Spaceweather gallery:
 
 
Stuart Thomson's gallery:
 
 
Sungrazers:
 
 
Sun Approaching Comets:
 
 
Conduct your own Earth-based search for a sungrazer:
 
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Tail detail from 23 December 2011 UT:
 
 
 
 
 
 
 
 
Click on images to enlarge...
Images are arranged from most recent at top to earliest at bottom.
 
 
Comet C/2011 W3 (Lovejoy) imaged on 12 February 2012 as the Moon began to move back in evening skies.  I was very surprised to be still able to get a faint trace of the tail, to about 7 degrees in length.  The comet was at around 70 degrees altitude.
 
 Sadly, this may be my last shot of the comet as I have pushed my basic gear to its limits and the comet is just getting too faint.  It has been a privilege to image and view this Great Comet from shortly after it was discovered in early December 2011 to its gradual disappearance from the sky, as far as mid-February 2012.
 
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Comet C/2011 W3 (Lovejoy), imaged 14:12, 30 January 2012 UT (1:12am 31 Jan local time).
 
A two-panel stitch of fields imaged 30 January 2012.  It may show very faint traces out to as far as 26 degrees but it is not conclusive.
 
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Comet C/2011 W3 imaged at 18mm on 25 January 2012.  About 26 degrees of tail is faintly detectable, although deeper images have shown the tail as detectable into the Milky Way, over 30 degrees.
 
 
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Comet C/2011 W3 imaged at 18mm on 20 January 2012.  The long tail is detectable faintly to the brighter part of the Milky Way, a length of 39 degrees.
 
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Comet C/2011 W3 imaged on 19 January 2012.  Canon 400D, 55mm, 3 x 3 min 20 sec, ISO 1600, F/4.5; 14:00 UT.  The object on the left edge of the frame is part of the Large Magellanic Cloud (LMC).
 
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Comet C/2011 W3 imaged on 18 January 2012.  The faint tail shows to a length of around 32 degrees.  There is the vaguest hint of a continuation to the Milky Way, a length of 37 degrees.
 
 
Here's the normally-processed version, with the tail barely visible.
 
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 By 16 January 2012, C/2011 W3 (Lovejoy) had faded so much that it was very difficult for me to get a trace of it photographically.  However the image above still showed the tail faintly to some 5 degrees beyond Nu Puppis, for a total tail length of 34 degrees.
 
 
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Faint spear of comet C/2011 W3 (Lovejoy) crossing over the Large Magellanic Cloud, 11:56, 14 January 2012 UT (10:56pm local time).  'Head' of comet at bottom right.
 
Highly processed widefield image taken on 14 Jan 2012, showing faint tail extension out as far as the brighter starfields of the Milky Way.  Tail length showing is at least 37 degrees and probably 45-46 degrees.
 
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On 13 January 2012, the comet appeared to be spearing through the centre of the Large Magellanic Cloud.  This image was taken at 11:27 UT in less than perfect transparency - the above is a crop from the full frame.
 
A highly-processed inverted version of the full frame image shows the faint tail extending to a distance of 21-22 degrees, the last small part out to the edge of the frame being lost in vignetting, or not there.
 
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The comet was beginning to pass over the Large Magellanic Cloud as moonlight began to move back in evening skies on 12 January 2012.  This shot, still moonlight-affected, was taken at 11:34 UT (10:34pm local time), just three washed-out 2 min subs.
 
 
The comet shows more clearly in this inverted image
 
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Fading streak of the comet tail in a slightly moonlight-affected image, 15:10, 04 January 2011 UT (2:10am 05 Jan local time).
 
Gif animation showing movement of tail between 02 and 04 Jan 2012 UT.
 
Star trail stack showing proximity of tail to South Celestial Pole.  The comet tail is the faint ghostly streak to the left of the Pole.
 
Head of comet, shot at 55mm in bright moonlight.  Shows the difficulty of photographing this large faint comet in a light sky.
 
 
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A dimming comet C/2011 W3 moving further out from the Milky Way,
14:40, 02 January 2012 UT (1:40am 03 Jan local time).
Canon 400D on tripod, 18mm, 8 x 50 sec, ISO 1600, F/4.5.
 
High contrast version of the above
 
This gif animation appears to show the faint tail extending through the top of the frame, indicating a tail length of at least 40 degrees.

The comet tail was still bright enough to show as a long ghostly streak when a star trail image was created from the subs 

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The long faint streak of comet C/2011 W3 (Lovejoy) as it exits the Milky Way,
14:15, 01 January 2012 UT (2 Jan local time).
Canon 400D on tripod, 18mm, 20 x 30 sec, ISO 1600, F/4
 
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Comet C/2011 W3 showing a long faint tail, 13:54, 31 December 2011 UT.
Canon 400D on tripod, 15 x 30 sec, ISO 1600, F/4.5.
 
High-contrast crop from the above, showing the long straight streak of the tail on the right of the Milky Way, starting near the bottom-right corner.
 
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Outer portion of tail of C/2011 W3 moving out of the Milky Way, 30-31 December 2011 (29-30 Dec UT).  The comet was rapidly losing brightness and apparent extent.
 
 
Close up view of movement of section of tail 30-31 December 2011 (29-30 Dec UT).  The two bright stars are Alpha and Beta Centauri, the Pointers to the Southern Cross.
 
 
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A dim tail exiting the Milky Way on 30 December 2011 (29 Dec UT).
Can't see it?  Check the following animation:
 
 
 
 
Two deep images taken of the dimmer portion of the tail were taken on 30 December and stitched together.  Can't see the tail?  Check the following:
 
 
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 On the morning of the 27th December 2011 (26 Dec UT) I went to a high lookout with a good south-easterly horizon and for the first time since the comet hit dark skies I was able to image the whole tail.  Visually it was still impressive although much dimmer than a few days before.  Naked-eye, I could trace 33-deg of the tail length and images showed faint extension out to perhaps 38-deg. 
Canon 400D, 18mm, 3 x 2-min, ISO 1600, F/4.5.  17:00, 26 December 2011 (4:00am 27 December local time, UT+11)
 
Crop from above image.
 
This is a shot of the comet head such as it was showing at the time, using a Canon 400D at 200mm zoom.
 
Image showing the first 10-deg of the tail, taken at 55mm, Canon 400D
 
 
Image showing 18-deg of the tail, taken at 55mm, Canon 400D.
 
 
Image of a short section of tail taken at 200mm zoom.  It shows no structure at all - compare this with the image below, taken three days before:
 
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I finally managed to observe the comet on 23 December (the morning of 24 December local time, Christmas Eve).  It was spectacular, like a big searchlight beam shining up into the sky.  I saw about 20-degrees of the tail rise, but by the time the head had risen above my hilly SE horizon the comet had been washed out by daylight.  The above image shows a small portion of the tail of C/2011 W3 on 23 December 2011.
 
Previous image, processed further to reveal tail detail.
 
 
 A longer section of the tail, imaged on 23 December 2011
 
 
The comet and the ISS (International Space Station), imaged at 18mm at 17:30, 23 December 2011 UT.
 
 
The comet, still not risen fully above my hilly horizon, disappearing in dawn light, 17:43, 23 December 2011 UT.  Canon 400D @ 18mm.
 
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My first attempt at imaging the growing C/2011 W3 in darker skies after perihelion was frustrated by cloud, with just a tantalising glimpse of the comet tail in a small gap.  17:33, 22 December 2011 UT.  Canon 400D @ 55mm.
 
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Comet C/2011 W3 imaged less than 5-degrees from the Sun on 17 December 2011, on its outward passage.  This was taken at 12:44pm local time (UT+11) with the Sun at 75-degrees altitude.  Canon 400D with aperture mask at 200mm.
 
 This object cannot be certainly identified as the comet because of the style of the shooting (off tripod).  However I am confident that the comet position was within the field, and by prepocessing each sub separately and blinking between them, one real object and one only was found, this one.  It appeared very faintly in the same position in each sub, and given that the comet was easily the brightest object in the field at this time it is a reasonable assumption that it is indeed the comet.  Stacking the pre-processed subs and applying further 'harsh' processing brought out the object above, with a faint apparent tail.
 
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I was lucky enough to image the comet while it was still on the NEO CP list, shortly before the comet discovery was announced.  This image is a composite - because stars trailed through the comet I cloned the nearby stars out of one set of subs (6 were usable) and stacked them on the comet, then cropped the comet out and layered it over a star stack. 02 December 2011.
 
 
Movement of comet C/2011 W3 over about 40 mins, 02 December 2011
 

Video animation of the above sequence

 
Comet C/2011 W3, 02 December 2011
 
Comet C/2011 W3, 02 December 2011
 
 
Here's the full stack of 9 subs with star trails going through the comet!
 
 
First image of C/2011 W3 on 02 December 2011, from four 1-minute subs
 
 
 
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