C/2011 W3 Lovejoy
The Great Southern Christmas comet of 2011
Closest to Sun: 2011 Dec 16 at 0.006AU
Closest to Earth: 2012 Jan 8 at 0.50AU
Maximum magnitude -3.


2011 December 21.7UT
Canon 300D camera, 50mm lens, ASA 200. 30 second exposures.

Who would have thought that a faint 13th magnitude fuzzy blob discovered by Terry Lovejoy in Queensland
on 2011 Nov 27.7UT would turn into a Great Southern Comet!
Initial orbital calculations indicated that it was a member of the Kreutz sungrazing group of comets.
In fact, when Terry emailed me his discovery positions, I recognised that the speed and direction was typical for a Kreutz sungrazer.
I literally fell off my chair, as this was the first pre-perihelion ground based detection of a Kreutz sungrazer, 
since Great Comet Ikeya-Seki in 1965.


2011 December 2.65UT
10x10second exposures. C11 SCT and Starlight Express MX7c CCD imager.
Motion is quite rapid and nucleus appears trailed
on 2011 Dec 6.72 UT I made a visual estimate through a C11 telescope at 84x and estimated magnitude 11.2
(observation slightly affected by twilight) This was a rare pre-perihelion visual observation of a Kreutz group member!

Perihelion was a mere 0.0055AU or 140,000kms from the solar surface on 2011 Dec 16.0UT.
Very few people expected it to survive, especially since the intrinsic magnitude at discovery was a mere mag 14.
This is much fainter than the norm. Clearly, the Kreutz sungrazers are in a class of their own because these objects have
already experienced intense heat at previous apparitions. The solar corona has a temperature of 2 million degrees.
You can imagine that on its previous encounter some 700 years age, it was baked into a pulp.
Thus on its next return, it displays minimal activity until very near the Sun, only emitting copious amounts of dust at perihelion.
The orbital period of comet Lovejoy is about 600-700yrs, typical of Kreutz members.
The comet appeared quite impressive in SOHO LASCO C3 images from Dec 14 at 3:00UT.
It dived into the sun on Dec 16.0UT and spectacularly appeared on the other side, shining at magnitude -4 but stripped of its tail.
Sure enough, a new tail started to rapidly develop as the head receded from the Sun as per below image on 2011 Dec 17
Sun is white disk in centre with occulting mask blocking the sunlight out


Credit SOHO

By the morning of 2011 Dec 22 (21.7UT) the comet had moved sufficiently far enough from the Sun to be visible in morning twilight.
From a backyard in suburban Adelaide, I observed a bright tail, 11 degrees long with the unaided eye through moderate light pollution.
The surface brightness of the tail was brighter than any portion of the milky way.
Clearly this was the best comet that I had seen, with the exception of comet McNaught in 2007.
The head however was considerably fainter, giving the impression of a "headless comet".
This approximates the description given to the great comet of 1887.




C/2011 W3 Lovejoy on 2011 December 21.7UT
Canon 300D camera, 50mm lens, ASA 200. 30 second exposures. Location: Adelaide, South Australia.
Moon is to the left of field. Head is below a bright streetlamp.


2011 December 23.7UT
Canon 300D camera, 50mm lens, ASA 200. 20 second exposures. Location: Goolwa, South Australia.
Unfortunately clouds interfered until start of twilight but comets bright tail could still be seen.

My next visual observation was form Goolwa on Christmas morning when the tail had grown out to a visual length of 20 degrees.

2011 December 24.7UT
Canon 300D, 50mm, asa800, 30 sec exposure. Location: Goolwa Beach, South Australia
Once again poor conditions but I managed to capture the comet through a gap in clouds.
The tail had grown to a visual length of 20 degrees, but the brightness appeared to be have faded slightly.

2 mornings later, I was back in Castlemaine and estimated the naked eye tail length as 30 degrees,
and photographically out to 40 degrees. Clearly the tail was growing rapidly but becoming fainter with each passing night.
It also had to compete with the bright milky way through Norma, Ara, Centaurus and Crux.


2011 December 26.71UT
Canon 300D, 18mm, iso1600, 10x30 sec exposures.


The pointers are above centre (Alpha/Beta Centauri), Southern Cross (Crux) is at top.
My best observation of this spectacular comet. The tail continues to fade but is offset by its increasing length as it approaches Earth.
This morning the tail is seen visually for 30 degrees, extending to Beta Centauri, with the first 10 degrees particularly bright
This photo shows a fainter extension out to 40 degrees.
Note the Emu (Aboriginal sky constellation) , the dark nebulosity running through the milky way is the neck
The head and beak are at top, better known as the Coalsack nebula.


6x30 sec exposures at 50mm cropped.
The first 10 degrees of tail remains bright and comparable to the Norma Starcloud, seen below the tail in this photo.
Note that the nucleus has completely disintegrated.
The brightest section of tail appears 4th magnitude whilst the head section appears 5th-6th magnitude


2011 December 28.71UT
Canon 300D, 18mm, iso1600, 10x30 sec exposures. Cropped.
Location: backyard in Castlemaine, Victoria. Slight interference with light pollution.
Tail is traceable to Alpha Centauri but milky way background now interfering


2011 December 30.71UT. Canon 300D, 18mm, iso1600, 14x30 sec exposures. Cropped. Eta Carinae nebula is at top.


2011 December 30.71UT at 50mm, 8x30 second exposures.
This image was taken from a dark site near Castlemaine.
The visual tail length with the unaided eye had reduced to 17 degrees and photographically about 25 degrees.
The bright milky way is interfering with the view.
The tail is continuing to fade with each passing morning and is now of similar surface brightness to the SMC.
Thus no longer likely to be observable from light polluted city skies.


2011 December 31.54UT A new Years Comet. Canon 300D, 18mm, iso1600, 6x30 sec exposures. Cropped.


2011 December 31.54UT A new Years Comet. With added fireworks display. Comets tail can be seen faintly above the tree.
Location: Castlemaine, Victoria.


2012 January 04.69UT
Canon 300D, 18mm, iso1600, 12x30 sec exposures. Cropped. Southern cross is left of centre.
Location: near Castlemaine, Victoria.
Approximately 10 degrees of tail was observed with the unaided eye using averted vision, extending just beyond Alpha Apus.
The intensity has dropped off substantially since my last observation on Dec 30.71, and is now a very difficult naked eye target.
Through 8x40mm Binoculars, the tail extends through to Beta Chameleonis for a total of 20 degrees.
Photographically the tail length is about 30 degrees, passing near Beta Carinae.
Interestingly the brightest section of tail now appears to be at the head of the comet.
I estimate this to be about magnitude 6.5



2012 January 15.50UT. Canon 300D, 90mm, iso800, 4x3min stacked exposure. Cropped.
Location: Castlemaine, Victoria.
Comet is now virtually undetectable through 8x40mm binoculars and is fainter than the LMC.
Photographically, a faint tail is seen about 3 degrees in length, skirting the edge of the LMC.
better seen in this inverted image below: The tail extends to Beta Doradii with image processing for a total of 9 degrees.

 

Below are my observations of comet C/2011 W3 Lovejoy in ICQ format

2011W3 2011 12 05.73 S 11.2 TK 28 T 6 84 1.0 5 ICQ nn MAT08
2011W3 2011 12 21.75 I 3.0:TK 0.7E 1 10.0 5 11.0 238 ICQ nn MAT08
2011W3 2011 12 24.75 I 4.0:TK 0.7E 1 10.0 3 20.0 230 ICQ nn MAT08
2011W3 2011 12 26.71 I 5.0:TK 0.7E 1 10.0 3 30.0 227 ICQ nn MAT08
2011W3 2011 12 28.71 I 6.0:TK 0.7E 1 10.0 3 20.0 227 ICQ nn MAT08
2011W3 2011 12 30.71 I 6.0:TK 0.7E 1 10.0 2 17.0 226 ICQ nn MAT08
2011W3 2012 01 04.69 I 6.5:TK 0.7E 1 10.0 2 10.0 220 ICQ nn MAT08
2011W3 2012 01 15.50 S 9.0:TK 4 B 8 5.0 1 2.0 50 ICQ nn MAT08

2011W3 111205.73 New Kreutz sungrazer, appears faint, small but moderately condensed. [MAT08]

2011W3 111221.75 Moonlight 12%. Despite light pollution, tail is brighter than any portion of the milky way [MAT08]
2011W3 111221.75 The straight tail is 11 degrees long with slight curvature towards Gamma Lupi [MAT08]
2011W3 111221.75 Through 8x40mm B, head appears disrupted, with very narrow V line neck. [MAT08]

2011W3 111224.75 Tail intensity reduced but length now 20 degrees with unaided eye. [MAT08]
2011W3 111224.75 Tail still brighter than milky way. Head is near zeta1,2 Sco [MAT08]

2011W3 111226.71 Naked eye tail length is now 30 degrees, extending to near Alpha Centauri. [MAT08]
2011W3 111226.71 The first 10 degrees of tail remains bright and comparable to the Norma Starcloud. [MAT08]
2011W3 111226.71 The brightest section of tail appears 4th magnitude whilst the head appears 5th-6th magnit [MAT08]
2011W3 111226.71 A 5 minute photograph reveals a 40 degree tail. [MAT08]

2011W3 111228.71 Tail is traceable to Alpha Centauri but milky way background now interfering. [MAT08]

2011W3 111230.71 Tail continues to fade, visual length reduced to 17 degrees. [MAT08]
2011W3 111230.71 Photographically tail extends 25 degrees beyond Alpha Circinus. [MAT08]
2011W3 111230.71 Tail surface brightness similar to SMC. [MAT08]

2011W3 120104.69 10 degrees of tail observed with the naked eye using averted vision, extending just beyond [MAT08]
2011W3 120104.69 Through 8x40mm binoculars, the tail extends through Beta Chameleonis for a total of 20 deg [MAT08]
2011W3 120104.69 Photographically the tail is 30 degrees passing near Beta Carinae. [MAT08]
2011W3 120104.69 Interestingly the head region appears brightest wheras previously the brightest region app [MAT08]

2011W3 120115.50 Comet is barely detectible and is fainter than outer regions of the LMC. [MAT08]
2011W3 120115.50 Photographically tail stretches 9 degrees to Beta Doradus. [MAT08]