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dan777
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Reged: 11/16/07

Loc: Indiana
Re: Comet C/2012 K5 is ready for chasing new [Re: Ira]
      #5585382 - 12/23/12 10:59 AM

Quote:

Any links to daily coordinates?



http://ssd.jpl.nasa.gov/horizons.cgi#results
Search Target Body for C/2012 K5 then click on Generate Ephemeris


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tboss70
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Reged: 11/25/05

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Re: Comet C/2012 K5 is ready for chasing new [Re: Ira]
      #5585458 - 12/23/12 11:54 AM

On my picture above, Im not sure if 3 minutes was too long or if the core just wasn't visible? Maybe my focus was off a little too?

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Centaur
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Reged: 07/12/04

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Re: Comet C/2012 K5 is ready for chasing new [Re: Ira]
      #5585542 - 12/23/12 12:48 PM

Quote:

Any links to daily coordinates?

/Ira




Yes, Ira, on my comets webpage: www.CurtRenz.com/comets

There you will find both the comet's coordinates for J2000.0 for standard maps, and for the current date as needed for aiming telescopes.


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Tonk
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Reged: 08/19/04

Loc: Leeds, UK, 54N
Re: Comet C/2012 K5 is ready for chasing new [Re: Centaur]
      #5586105 - 12/23/12 06:32 PM

Quote:

Any links to daily coordinates?




Yes lots - the Harvard / MPC ephemeris is best

MPC ephemeris

BAA ephemeris

"Astrosite" charts

Skyhound charts



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Ira
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Reged: 08/22/10

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Re: Comet C/2012 K5 is ready for chasing new [Re: Tonk]
      #5586222 - 12/23/12 08:24 PM

Thanks!

/Ira


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Centaur
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Reged: 07/12/04

Loc: Chicago
Re: Comet C/2012 K5 is ready for chasing new [Re: Ira]
      #5586462 - 12/23/12 11:41 PM

Quote:

Thanks!

/Ira




Youíre welcome, Ira. Iím glad everyone is having fun with this comet.

Iíve updated my ephemeris and graphics for this comet to its osculating orbital elements of epoch 2013 JAN 01.0. Previously they were for epoch 2012 NOV 29.0. Other sources still depend on much earlier epochs, despite the effects of planetary perturbations. The elements I use were provided by Dr. Aldo Vitaglianoís highly accurate Solex astronomical numerical integration program: http://main.chemistry.unina.it/~alvitagl/solex . I then run them through the orbit determination algorithm of his friend Jean Meeus. BTW, Aldo is a member of the Cloudy Nights message board. See his latest contribution at post #2 in the thread at: http://www.cloudynights.com/ubbthreads/showflat.php/Cat/0/Number/5570752/page...

The cometís coordinates in my ephemeris are given in decimal form. Thatís to ease interpolation, i.e. the process of estimating positions at moments other then 00 UT.

Linear interpolation usually suffices to determine an intermediate position P:

A = Position at Day 1
B = Position at Day 2
F = Fraction of a Day since A ( 12 hours would be 0.5 )
P = A + ( B Ė A ) x F

However, when an object appears to traverse the sky rapidly as this comet is now, second degree interpolation will provide greater accuracy:

A = Position at Day 1
B = Position at Day 2 ( nearest 00 UT to time in question )
C = Position at Day 3
D = ( C Ė A ) / 2
E = ( C + A ) / 2 - B
F = Fraction of a Day since B ( F can be negative, although F≤ is always positive )
P = B + D x F + E x F≤

My comet ephemerides and related graphics are at: www.CurtRenz.com/comets

Edited by Centaur (12/24/12 02:44 PM)


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Dave Mitsky
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Re: Comet C/2012 K5 is ready for chasing new [Re: Centaur]
      #5586690 - 12/24/12 06:32 AM

Despite moonlight and poor transparency, I was able to locate and observe Comet C/2012 K5 (LINEAR) this morning using the 17" f/15 classical Cassegrain at the ASH Naylor Observatory. I used magnifications of 162, 185, 216, and 259x initially.

The comet sported a somewhat condensed nucleus and a rather short tail that fanned out in a narrow fashion.

By the time the moon had set, the transparency had improved and I had a far better view of the 8th-magnitude comet. At 360x, the comet's motion was apparent in the span of approximately ten minutes.

While I couldn't see C/2012 K5 (LINEAR) through the 5" f/5 finder scope earlier, I was able to spot it at 35 and 45x after the conditions had improved.

Dave Mitsky


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MessiToM
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Reged: 12/21/09

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Re: Comet C/2012 K5 is ready for chasing new [Re: Dave Mitsky]
      #5586980 - 12/24/12 10:51 AM

I also was able to view this comet this morning 3am est. Using a 17.5" reflector it was "obvious" as was the fan tail and "long" nucleus. Using averted vision helped greatly though.

I forgot to mention seeing was only so so. I'd say transparency of 2 or 3 out of 5

Edited by MessiToM (12/24/12 10:55 AM)


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Bagleys
journeyman


Reged: 09/27/10

Loc: Lake St. Louis, Missouri
Re: Comet C/2012 K5 is ready for chasing new [Re: MessiToM]
      #5587150 - 12/24/12 12:28 PM

I saw it from my driveway at 2AM Saturday Morning with the 13" Coulter. Elongated center was clearly visible but just a hint of tail with averted vision. It was really exciting. Seeing and transparency were good but I have plenty of light pollution (street lamp about 50 feet away). Stellarium has it at around 10.5 MAG now and brightest on the 30th, then beginning to dim in January.

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MessiToM
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Reged: 12/21/09

Loc: Huntingdon PA
Re: Comet C/2012 K5 is ready for chasing new [Re: Bagleys]
      #5587218 - 12/24/12 01:13 PM

I didnt know stellarium showed comets. Ive been using sky tools 3 and starry night

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Tonk
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Reged: 08/19/04

Loc: Leeds, UK, 54N
Re: Comet C/2012 K5 is ready for chasing new [Re: MessiToM]
      #5587326 - 12/24/12 02:34 PM

Quote:

I didnt know stellarium showed comets




You can hook up directly to MPC comet data see instructions here - http://stargazerslounge.com/topic/113971-adding-comets-asteroids-and-small-bo...


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dan777
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Reged: 11/16/07

Loc: Indiana
Re: Comet C/2012 K5 is ready for chasing new [Re: Bagleys]
      #5587756 - 12/24/12 09:14 PM

Quote:

Stellarium has it at around 10.5 MAG



It's difficult to predict an accurate magnitude of a comet. Stellarium typically sets Albedo=1 in it's definition file (ssystem.ini) for all comets. So the actual magnitude can easily differ by a couple of magnitudes from what Stellarium shows it to be.


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Dave Mitsky
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Re: Comet C/2012 K5 is ready for chasing new [Re: dan777]
      #5587874 - 12/24/12 11:12 PM

C/2012 K5 (LINEAR) is currently in the eighth-magnitude (or so) range.

Dave Mitsky


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Tonk
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Reged: 08/19/04

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Re: Comet C/2012 K5 is ready for chasing new [Re: Dave Mitsky]
      #5588100 - 12/25/12 05:10 AM

Quote:

It's difficult to predict an accurate magnitude of a comet




Possibly - but its not to hard to take measurements and fit the results to well established modeling equations to get a reasonable prediction of future brightness - assuming no future disruptions, switch offs etc

The current best fit for estimating the brightness of this comet is:

m1(t) = 9.5 + 5 log d + 13.0 log r

(where d is the geocentric distance and r is the heliocentric distance at date/time t. I.e. M0 = 9.5 and n = 5.2 in standard eq M1 = M0 + 5 log d + 2.5n log r)

If you want up to date brightness measurements and future trends then look here

http://www.aerith.net/comet/catalog/2012K5/2012K5.html

Scroll down for the graph


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BrooksObs
professor emeritus


Reged: 12/08/12

Re: Comet C/2012 K5 is ready for chasing new [Re: Tonk]
      #5588248 - 12/25/12 09:47 AM

A word or two concerning comet magnitude predictions seen on Internet sites and blogs might prove worth while at this juncture considering we have comets PANSTARRS and ISON in the offing. The unfortunate situation regarding the "best fit" photometric parameters put forth on nearly all the Internet sites are based on the combined unevaluated/unadjusted data from a large cross section of observers of unknown actual experience in estimating comet brightnesses, which is an art in itself which relatively few observers ever truly master.

Likewise, allowance for the nature and size of the instruments being employed for the observations are mostly also neglected, even though these have been known to introduce a significant bias for decades. These two factors alone, and there are others that are likewise neglected, typically lead to derived formulae resulting in excessively bright magnitude predictions as compared to what is later seen.

In the case we have here in Comet 2012K5, the value of "n" derived from the raw data implies a value of 5.2 (2.5*n) which if taken at face value would be a surprisingly large figure, one far more commonly seen as applicable to a short period comet.

Unfortunately, one sees this sort of situation arising all too often in regard to Internet predictions of major comet brightness and leading to excessively high predicted mgnitudes for some future date when the object is near periheliion...as was the silliness surrounding Comet Elenin last year, which never had a real chance of becoming a significant object.

Brooks Obs

Edited by BrooksObs (12/26/12 03:56 PM)


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astrocy
super member


Reged: 11/28/09

Re: Comet C/2012 K5 is ready for chasing new [Re: BrooksObs]
      #5589510 - 12/26/12 11:13 AM

Early this morning under a dark and moonless sky, I was able to spot the comet using 15x70 binoculars near the stars 23 UMa and 16 UMa, not far away from the boarder of Ursa Major with Lynx. The comet had an elongated nebulous appearance and its coma was visible with direct vision despite its low magnitude. A hint of a tail was also suspected with averted vision.

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Aquarellia
professor emeritus


Reged: 10/27/12

Loc: Provence, France
Re: Comet C/2012 K5 is ready for chasing new [Re: astrocy]
      #5590635 - 12/27/12 01:12 AM

Hi, you can have a look to two sketches :
http://www.cloudynights.com/ubbthreads/showflat.php/Cat/0/Number/5583470/page...
Made with a 102/1000 refractor with 40mm EP.
Michel


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Aquarellia
professor emeritus


Reged: 10/27/12

Loc: Provence, France
Re: Comet C/2012 K5 is ready for chasing new [Re: Special Ed]
      #5590637 - 12/27/12 01:16 AM

Quote:

Got my first look at C/2012 Linear


Nice Spťcial ED ! Well done Michel

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Dave Mitsky
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Reged: 04/08/02

Loc: PA, USA, Planet Earth
Re: Comet C/2012 K5 is ready for chasing new [Re: Aquarellia]
      #5591483 - 12/27/12 05:09 PM

There's a fine image of C/2012 K5 (LINEAR) posted at http://www.cometpieces.at/images/phocagallery/2012k520121213lrgbweb_2.jpg

It was captured by Michael Jšger on December 13th.

http://www.cometpieces.at/

Dave Mitsky


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MessiToM
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Reged: 12/21/09

Loc: Huntingdon PA
Re: Comet C/2012 K5 is ready for chasing new [Re: Dave Mitsky]
      #5594159 - 12/29/12 10:59 AM

"forbidden" to follow that link

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