C/2011 L4 PANSTARRS

The Great Binocular Comet of March 2013
Closest to Earth on 6 March 2013 at 1.09AU
Closest to Sun on 10 March 2013 at 0.30AU
Maximum magnitude 1 in mid March 2013


C/2011 L4 PANSTARRS on 2013 March 1.4UT
Canon 60Da and 200mm lens cropped , 3 minute exposure.
The 3 tails of comet PANSTARRS
At top is the faint narrow type I gas or ion tail - 3 degrees long
below this is the broad bright Type II dust tail - 2.5 degrees long
running left at bottom is the Type III dust "trail" - 1 degree long. (made of heavy dust particles)

Comet PANSTARRS arrived at perihelion on 2013 March 10 at a distance of 0.3AU from the Sun.
It was recovered in January morning skies as a magnitude 8 object, but observations during January seem to indicate
that its rate of brightening was slowing down. This was expected for a dynamically new comet.
High activity well away from the Sun driven by highly volatile gas such as CO2 but fading as it approaches the Sun, where H2O
sublimation needs to take over.
It peaked at magnitude 1, still bright by cometary standards but as it was situated in twilight, it needed to be bright to be conspicuous.
A clear south eastern and south western horizon was required to spot the comet.

Here are some of my observations during Feb and March 2013.
2013 Feb 15.75UT: comet appeared at magnitude 5.0 with a prominent dust tail 50’ long and faint ion tail nearly 2 degrees on a photograph.
2013 Feb 28.41UT: Moving into the evening sky, the comet appeared significantly brighter at magnitude 2.6.
Through 25x100mm binoculars, the main type II dust tail measured 1.5 degrees in PA 165.
A short type III dust “trail” was visible for 1/2 degree in PA 205.
The faint ion tail was not visible visually but measured 2 degrees on a photo.
2012 March 1.4UT: This was the best night for observation as recent rain improved the sky quality. The bright dust tail measured
2.5 degrees, the fainter trail about 1 degree and the very faint ion tail 3 degrees (visible only on a photograph)
2012 March 4.42UT: Comet now magnitude 2.0 and easily visible to the unaided eye with a short tail.
By March 8th, the comet appeared near Iota Ceti (mag 3.5), however twilight was more overwhelming.
The show was virtually over for us southerners as it made its way to Northern hemisphere skies.

(observations below with most recent at top)



2013 March 5.42UT.
Comet in deep twilight and probably my last observation.  Canon 60Da


2013 March 4.42UT
Taken through Canon 300D and 300mm lens. Note the difference between this old camera and my new 60Da shots.
Less sensitive but can still do a reasonable job.
Visual magnitude 2.0. Dust tail length 2.5 degrees.


2013 March 3.42UT.

stack 2.5 minutes at 300mm. Canon 60Da


2013 March 3.42UT
single 1.5 minute exposure and 100mm zoom lens. The dust tail length is 2.5 degrees.


2013 March 1.4UT
Left: Canon 60Da and 300mm zoom lens cropped.
 


2013 Feb 28.41 UT
Canon 60Da, 3x1 minute stack. 300mm lens, cropped. Magnitude 2.6. Power lines interfere with view.
In 25x100mm binoculars, the dust tail measured 1.5 degrees in PA165, with the much fainter and shorter type 3 dust trail in PA 205.
The ion tail was not visible visually but is at least 2 degrees long in PA155

2013 Feb 28.41 UT
10x5 second exposures. starlight express MX7c CCD imager, Celestron C11 telescope.
Digitally processed to show detail in the head. Note the dark lane running up the tail.
This is a feature commonly seen in dusty comets where the nucleus acts as a barrier to the escaping dust and creates a vacant zone


2013 Feb 23.41 UT
Canon 60Da, 30 seconds. 100mm lens, cropped. Magnitude 3.8.


2013 Feb 17.75 UT
Canon 60Da, 3x2 minute stack. 300mm zoom lens, cropped.


2013 Feb 15.75 UT
Canon 60Da, 5x2 minute stack. 300mm zoom lens, cropped. Magnitude 5.0.
Dust tail 50' and ion tail nearly 2 degrees long. Magnitude 6 star is just above comet head.



2013 Feb 8.75 UT
Canon 60Da, 5x2 minute stack. 300mm zoom lens, cropped. Magnitude 5.9.
The ion tail is nearly 1 degree in PA 210 whilst the leading edge of the dust tail is 30' in PA 250.
Notice the broad dust fan.


2013 Feb 2.73 UT
Canon 60Da, 5x2 minute stack. 300mm zoom lens, cropped. Magnitude 6.7. Bright stars to the left are Beta 1,2 Sgr.


2013 Jan 27.7UT
Canon 60Da, 5x20sec stack, C11 telescope at F6. Full moon interference.


2013 Jan 19.73UT
Canon 60Da, 5x2 minute stack. 300mm zoom lens. Globular cluster NGC 6541 at top left.

 
Left: 2013 Jan 16.73 UT
Canon 60Da, 5x2 minute stack. 300mm zoom lens, cropped. Globular cluster NGC 6541 is on the right.

Hidden from view by the Sun since October 2012, comet PANSTARRS reappeared as a magnitude 8.5 object in early January,
situated in the tail of the Scorpion before dawn. By the end of the month, it brightened to magnitude 7.0.
Moon free period occured between January 11 to 24.
Observations during January seem to indicate that its rate of brightening slowed down. This is what is expected for a dynamically new comet.
It may only peak at magnitude 2 in March, still bright by cometary standards, but situated in twilight.
A clear south eastern and south western horizon was required to spot the comet.
On February 1, the magnitude 6 comet was situated in Telescopium, low in the southeastern sky before dawn,
near the bright pair Beta 1,2 Sgr. Moonlight interferee with the view until Feb 9.
On the morning of Feb 11, the now magnitude 5.0 comet was 2 degrees northwest of Alpha Indii, still maintaining low elevation.
The magnitude 9 comet C/2011 F1 LINEAR was also in the near vicinity.
The comet enterd Grus on Feb 18, and brightened to magnitude 4.0.
Observing circumstances then started to get difficult, with the comets elongation decreasing to 23 degrees by the end of
February, but this was compensated somewhat by its rapid brightening.
On Feb 21, the mag 4.0 comet was adjacent to mag 4.6 star Lambda Gruis.
The comet was in solar conjunction on 2013 Feb 23, and then appeared into the evening sky, low in twilight.
On Feb 25, the now magnitude 3.0 comet was a degree south of mag 4.5 star Gamma PsA.
By the start of March, moonlight no longer interfered, and C/2011 L4 and C/2012 F6 could be seen simultaneously with the
unaided eye from a dark southern hemisphere site.



2012 Sep 9.40UT.
20x10 second exposures. C11 SCT and Starlight Express MX7c CCD imager.


 

Personal lightcurve vs MPC prediction(red) updated Feb 7. H=5.6, n=2.6
Predicted peak magnitude of 2.0 in March 2013. (POST NOTE comet made slightly better than this)