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Comet C/2011 L4 (PANSTARRS)

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#51 Tonk

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Posted 17 February 2013 - 06:07 PM

So, astro photographers are likely to be faced with a catch as catch can senario, attempting to trade off comet altitude, favorable tail direction, twilight and moonlight interference to gain any impressive images.


Indeed - with ten years of comet photography under my belt, this one is proving to be a hard plan!

#52 Special Ed

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Posted 17 February 2013 - 06:46 PM

Of course, all this is educated speculation at this point.

Have your cameras and pencils ready, folks. :)

#53 Rich (RLTYS)

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Posted 18 February 2013 - 07:44 AM

We can only hope.

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#54 BrooksObs

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Posted 18 February 2013 - 11:57 AM

Far from mere speculation, I'm afraid, Special Ed. In the case of Comet PanSTARRS the facts conspire to give us the least favorable viewing circumstances for any bright comet in decades.

BrooksObs

#55 eps0mu0

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Posted 18 February 2013 - 09:09 PM

Least favorable viewing circumstances in decades?
At least we'll get a chance.
I seem to remember Kohoutek also had less than optimal viewing circumstances: low in the evening sky right after sunset. I was a fairly young and inexperienced observer, but I was unable to catch it, even though both Venus and Jupiter provided helpful guideposts in the sky.

#56 Special Ed

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Posted 18 February 2013 - 10:09 PM

Far from mere speculation, I'm afraid, Special Ed. In the case of Comet PanSTARRS the facts conspire to give us the least favorable viewing circumstances for any bright comet in decades.

BrooksObs


Hey--not "mere" speculation--I said "educated" speculation. I think you and Tonk and Jure are awesome (and I never use that word).

I'm just hoping that we visual observers and sketchers can see and record something that eludes the AP types (because of exposure issues, etc.).

#57 Dave M

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Posted 18 February 2013 - 11:27 PM

Nice shot of PANSTARRS on spaceweather
http://spaceweather....upload_id=76708

#58 Rich (RLTYS)

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Posted 19 February 2013 - 06:17 AM

WOW! A beautiful image.

Rich (RLTYS)

#59 Special Ed

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Posted 19 February 2013 - 06:31 AM

Indeed. :cool:

#60 BrooksObs

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Posted 19 February 2013 - 09:05 AM

Least favorable viewing circumstances in decades?
At least we'll get a chance.
I seem to remember Kohoutek also had less than optimal viewing circumstances: low in the evening sky right after sunset. I was a fairly young and inexperienced observer, but I was unable to catch it, even though both Venus and Jupiter provided helpful guideposts in the sky.


In point of fact even Comet Kohoutek was far better situated in the sky for observation by northern hemisphere observers than will be PanSTARRS. Kohoutek rose steadily upward from the SW horizon and away from the twilight as January of '74 progressed. PanSTARRS, on the otherhand, will virtually parallel the western horizon from mid March until well into April, never being higher up than 5-10 degrees an hour after sunset in twilight and essentially setting by the time full darkness comes. A nice binocular object in the afterglow of dusk perhaps, but no naked eye spectacle.

Incidentally, looking back over my observing journals, which span 1957 to the present, I cannot find any "bright" comet that was ever so continuously poorly placed for observation from my site following its perihelion as is PanSTARRS!

BrooksObs

#61 Tonk

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Posted 19 February 2013 - 09:54 AM

I cannot find any "bright" comet that was ever so continuously poorly placed for observation from my site following its perihelion as is PanSTARRS!


Indeed - should be called PantsARRS

#62 AlaskaIsCold

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Posted 20 February 2013 - 10:52 PM

I really hope that it puts on a reasonably good show.
But even if it does. Odds are I wont be able to image it.
I mean really how often do you hear "It was a star filled crystal clear march night in anchorage alaska." hahaha. Still though *fingers crossed*

#63 SabiaJD

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Posted 21 February 2013 - 05:32 PM

Least favorable viewing circumstances in decades?
At least we'll get a chance.
I seem to remember Kohoutek also had less than optimal viewing circumstances: low in the evening sky right after sunset. I was a fairly young and inexperienced observer, but I was unable to catch it, even though both Venus and Jupiter provided helpful guideposts in the sky.


In point of fact even Comet Kohoutek was far better situated in the sky for observation by northern hemisphere observers than will be PanSTARRS. Kohoutek rose steadily upward from the SW horizon and away from the twilight as January of '74 progressed. PanSTARRS, on the otherhand, will virtually parallel the western horizon from mid March until well into April, never being higher up than 5-10 degrees an hour after sunset in twilight and essentially setting by the time full darkness comes. A nice binocular object in the afterglow of dusk perhaps, but no naked eye spectacle.

Incidentally, looking back over my observing journals, which span 1957 to the present, I cannot find any "bright" comet that was ever so continuously poorly placed for observation from my site following its perihelion as is PanSTARRS!

BrooksObs


As stated above, Kohoutek was a difficult comet to find in early twilight the first week of Jan 1974. By the second week of January 1974, it was higher in altitude and easily seen against a darker background sky before setting.

This image of C/1973 E1 Kohoutek take on January 4,1974 EST. KAF 500 Slide Film, 400mm telephoto lens mounted on a equatorial mount. Taken by my friend Ken Mason

Stars on right are Alpha and Beta Capricorni

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#64 Tonk

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Posted 21 February 2013 - 06:33 PM

Wow - brings back memories. Kohoutek was my first astronomical observation and my entry into the astronomy hobby :)

#65 BrooksObs

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Posted 23 February 2013 - 09:04 AM

Updating my previous posts concerning the evolution of C/2011 L4, it is significant to note that no sightings of the comet seem to have been reported by southern hemisphere observers over the past 3 days as the comet moves ever deeper into the twilight. At last report PanSTARRS was 4th magnitude with a 1 degree tail, situated very low in the afterglow of dusk about 29 degrees almost due south of the Sun and visible only briefly in nautical twilight. Although continuing to brighten steadily, it seems ever more likely that the comet may become temporarily lost in twilight as its elongation from the Sun dwindles to just 15 degrees between now and March 10th. Just when it might be visually recoverable by northern hemisphere observers remains open to question and highly dependent on just how bright the comet becomes.

As of today selected photometric observations covering the past 6 weeks indicates a very steady but slow rise in the comet's brightness and development. An analysis of these data indicate that they can be very well represented by the formula:

m1 = 5.6 + 5 log(D) + 6.9 log®

as can be seen from the graph presented below.

Posted Image

These parameters, only very slightly differing from those presented earlier, but now even more certain, suggest a peak brightness of about +2.2 on or about March 10th, with a slow progressive fading thereafter taking the comet to about magnitude +5.0 by month's end.

These parameters also imply a resemblance to Comet Mrkos, 1957 P1, both in regard to observational geometry and brightness. If this is true, then PanSTARRS could put on a fairly respectable showing during late March and early April although heavily impacted by the inconvenient timing of the March full moon.

If PanSTARRS attains 2nd magnitude it should likewise exhibit a fairly broad, strongly curving, dust tail between 5 and 15 degrees in extent. How much of this will be suppressed by the bright twilight in mid March is, of course, open to question. However, those with the lowest western horizons and clearest, darkest, skies are likely to be favored since this will allow following the comet as late as possible in the dying twilight glow.

BrooksObs

#66 Rich (RLTYS)

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Posted 25 February 2013 - 06:35 AM

Wow - brings back memories. Kohoutek was my first astronomical observation and my entry into the astronomy hobby :)


The latest issue of S&T has a good article on Kohoutek.

Rich (RLTYS)

#67 RobK

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Posted 25 February 2013 - 11:29 PM

...it is significant to note that no sightings of the comet seem to have been reported by southern hemisphere observers over the past 3 days as the comet moves ever deeper into the twilight.


Not quite right, there has been a steady stream of sightings right through. You probably need to cast your net a bit wider, into southern astronomy forums, groups, blogs etc. The comet has been both a morning and evening object recently - in evening skies, I first imaged it on 17 Feb and since then there have been regular evening sightings, images and observations. Observations are the problem due to the difficulties with bright skies but some experienced observers are now reporting it in the mag 3s. I last saw it visually on the morning of 16 Feb (15 Feb UT) in fairly bright sky after it had cleared an annoying cloud band! It was beautiful, a 'classic' comet - a small, very bright inner coma (false nucleus) surrounded by a small coma swept back into a large broad fan tail, with a bright edge each side. And this was through a very modest telescope.

Regardless of its performance at perihelion and observing it in bright skies, I think you northerners have a real treat in store for you! I'm still hoping to get another look at it, but first I have to get rid of bushfire smoke and cloud which has plagued me since the 17th!

Cheers -

Rob

#68 RobK

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Posted 26 February 2013 - 12:01 AM

FWIW here's my PANSTARRS images from 15 & 17 Feb. All were taken in bright sky through thin cloud. There are a lot better than these around! The garish one from 17th was particularly difficult, with the comet at less than 3-deg altitude, twilight background glow and a bright Moon illuminating a band of haze and smoke.

Rob

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#69 Rich (RLTYS)

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Posted 26 February 2013 - 07:22 AM

Rob, nice images of Comet Panstarrs, thanks for the views. At this point I'm quite jealous. :bawling:

Rich (RLTYS)

#70 RobK

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Posted 26 February 2013 - 07:41 AM

Thanks Rich, I suspect I'll be the one who is jealous shortly! ;)

I should add in regard to the image on 17 Feb that it is presented at a much wider scale than the other two - aside from the poor sky condition, there was a another hiccup in that my polar alignment slipped without me noticing and hence there was bad star trailing.

Cheers -

Rob

#71 Special Ed

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Posted 26 February 2013 - 10:09 AM

Rob,

Thanks for the report and images--they look good. :)

#72 BrooksObs

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Posted 26 February 2013 - 11:28 AM

...it is significant to note that no sightings of the comet seem to have been reported by southern hemisphere observers over the past 3 days as the comet moves ever deeper into the twilight.


Not quite right, there has been a steady stream of sightings right through. You probably need to cast your net a bit wider, into southern astronomy forums, groups, blogs etc. Rob


To be honest, Rob, I peruse mostly those sites posting reliable observations from experienced comet observers, north and south, because of the often mistaken and error-prone posts one sees on so many of the "popular" astronomy websites.

As things stood, for the first time in weeks a 5-day gap (Feb 20-25) appeared in the posted data on the sites I cover. Only last evening did a new, rough, observation from the evening of the 24th get posted by John Drummon of Gisborne, NZ. John noted the comet to be "about" magnitude 3.0 with a short tail, situated very low in the sky deep in the evening twilight. This approximate magnitude is in rather good agreement with the parameters I had posted earlier.

Unfortunately, the comet's position in bright twilight and with a lack of much in the way of really suitable comparison stars is likely going to severely hamper accurate observation of PanSTARRS for some time to come, as the same difficulties will prevail when the comet first becomes visible to northern observers.

Incidentally, nice photos on your part!

BrooksObs

#73 krp

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Posted 26 February 2013 - 05:50 PM

Nice shots Rob. How much did you crop that last one?

#74 jiahao1986

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Posted 26 February 2013 - 06:08 PM

This Japanese folk Minoru Yoneto in New Zealands has been following the comet photographically with a decent setup.

http://homepages.ihu...oneto/camel.htm

His latest photo of the comet taken on the 22nd (UT) shows a dust tail of 2 degrees. The ion tail was still rather weak though.

Anyways this is a great resource for up-to-date photographic references on the comet's development. Looking at the lovely dust tail I'm sure we northerners have something great in store awaiting.

Jack

#75 Ptarmigan

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Posted 26 February 2013 - 08:42 PM

Nice image of PANSTARRS. Looks rather bright. :cool:






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