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Dave Mitsky
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Re: Comet C/2011 L4 (PANSTARRS) [Re: Dave M]
      #5646205 - 01/27/13 02:53 PM

It certainly would.

Dave Mitsky


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BrooksObs
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Reged: 12/08/12

Re: Comet C/2011 L4 (PANSTARRS) [Re: Dave M]
      #5646293 - 01/27/13 03:48 PM

For what it may be worth, I have just performed a linear regression analysis of 24 Southern Hemisphere visual magnitude estimates spanning 2013 January 01 to 26. The results indicate the following brightness formula prevails:

m1 = 5.98 + 5 log(D) + 7.59 log(r) , n = 3.04

I would note that this is in reasonably good agreement with parameters independently determined by Yoshida recently and indicating a much reduced peak brightness in March than had initially be projected.

However, I would add that the scatter in the data is definitely more that I would like to see.

BrooksObs

Edited by BrooksObs (01/27/13 08:06 PM)


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Jure Atanackov
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Reged: 05/04/10

Re: Comet C/2011 L4 (PANSTARRS) [Re: BrooksObs]
      #5646769 - 01/27/13 07:34 PM

I did a similar exercise a couple of days ago with 31 estimates from January 01 to 25 and got: H0=5.7, n=2.8. Both sets of photometric parameters give peak brightness at m1=2.3 (but that's still six weeks away).
Clear skies!
Jure


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pogrzex
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Reged: 01/25/13

Re: Comet C/2011 L4 (PANSTARRS) [Re: Jure Atanackov]
      #5656235 - 02/01/13 12:06 PM

It's now Feb. the Moon is slowly going away I'm waiting for another obs.

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MikeBOKC
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Re: Comet C/2011 L4 (PANSTARRS) [Re: pogrzex]
      #5656255 - 02/01/13 12:18 PM

There are some good locator charts for PANSTARRS in the new March issue of S&T.

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Tonk
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Re: Comet C/2011 L4 (PANSTARRS) [Re: MikeBOKC]
      #5656287 - 02/01/13 12:39 PM

Even better ones here

http://cometchasing.skyhound.com/

and here

http://www.shopplaza.nl/astro/comets/comets.htm


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Centaur
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Re: Comet C/2011 L4 (PANSTARRS) [Re: pogrzex]
      #5656354 - 02/01/13 01:19 PM

Quote:

It's now Feb. the Moon is slowly going away I'm waiting for another obs.




Comet C/2011 L4 (PANSTARRS) will reach its maximum southerly declination of 45.6 on 2013 FEB 05 where it is essentially out of sight for observers well north of the tropics. However it will soon be headed northward as the charts and ephemeris on my comets webpage indicate: www.CurtRenz.com/comets

During late February the comet will appear to pass the first magnitude star Fomalhaut. The separation will be only 2.5 on February 26. Unfortunately the Sun will also appear in the vicinity. Below is an equatorial chart I created to illustrate the close approach.



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pogrzex
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Reged: 01/25/13

Re: Comet C/2011 L4 (PANSTARRS) [Re: Centaur]
      #5657610 - 02/02/13 05:58 AM

Hi, of course I know about March visibility. I had rather in my mind another southern hemisphere observations confirming or denying this very weak 3 magnitude...

Edited by pogrzex (02/02/13 05:58 AM)


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BrooksObs
professor emeritus


Reged: 12/08/12

Re: Comet C/2011 L4 (PANSTARRS) [Re: pogrzex]
      #5657707 - 02/02/13 08:46 AM

It would appear that all the most recent incoming photometric data on PanSTARRS only serves to confirm the recent (not unanticipated) reduced rate of brightening. As of yesterday morning the comet was reported as of magnitude 6.5 with a 6' coma and a 0.2-degree, slightly curving, dust tail directed toward the NW.

Once again re-evaluating the growing body of photometric data ths morning and using 26 selected observations spanning Jan. 01 to Feb 02 results in the formula:

m1 = 5.6 + 5 log(D) + 6.6 log r

implying a maximum brightness of no more than +2.0

BrooksObs

Edited by BrooksObs (02/02/13 11:12 AM)


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Tonk
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Re: Comet C/2011 L4 (PANSTARRS) [Re: BrooksObs]
      #5658116 - 02/02/13 01:05 PM

Its been a while since a mag +2 comet anyway so I wont sniff at that.

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Special Ed
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Re: Comet C/2011 L4 (PANSTARRS) [Re: Tonk]
      #5658188 - 02/02/13 01:45 PM

Yep.

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pogrzex
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Reged: 01/25/13

Re: Comet C/2011 L4 (PANSTARRS) [Re: Special Ed]
      #5659337 - 02/03/13 03:53 AM

Consider that +2 mag is now optimistic scenario.

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Ptarmigan
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Re: Comet C/2011 L4 (PANSTARRS) [Re: Tonk]
      #5662494 - 02/04/13 09:13 PM

Quote:

Its been a while since a mag +2 comet anyway so I wont sniff at that.




I would not laugh at a magnitude 2 comet either as they are rare as well. Comets are hard to predict.


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pogrzex
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Reged: 01/25/13

Re: Comet C/2011 L4 (PANSTARRS) [Re: Ptarmigan]
      #5664750 - 02/06/13 07:48 AM

Hey, the comet is now making nice gas tail. What does it mean for us?

http://spaceweather.com/submissions/pics/m/Minoru-Yoneto-3238_1360123770_lg.jpg

Edited by pogrzex (02/06/13 10:14 AM)


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Dave M
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Re: Comet C/2011 L4 (PANSTARRS) [Re: Ptarmigan]
      #5664850 - 02/06/13 09:21 AM

I`ll take a mag 2 comet any day of the week

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BrooksObs
professor emeritus


Reged: 12/08/12

Re: Comet C/2011 L4 (PANSTARRS) [Re: pogrzex]
      #5665041 - 02/06/13 11:33 AM

Quote:

Hey, the comet is now making nice gas tail. What does it mean for us?

http://spaceweather.com/submissions/pics/m/Minoru-Yoneto-3238_1360123770_lg.jpg




Probably nothing very heartening, I'm afraid. Were PanSTARRS a more active comet one would have anticipated the development of an ion tail significantly early than this. In fact, there apparently still wasn't a detectable one even as late as last week! By way of comparison look at the ion tail on Comet Lemmon which is more typical of a type I tail (and has been present for some time) while currently at 1.2 a.u. from the Sun. Then compared that with PanSTARRS', with that comet at 0.91 a.u. Pretty darn weak, I'd say.

Likewise, the latest observations would seem to indicate that the comet's brightness may be beginning to fall behind even that predicted by the magnitude formula I had posted up-stream, making the prediction of a peak brightness of +2.0 in mid March ever less likely.

BrooksObs

Edited by BrooksObs (02/06/13 12:42 PM)


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azure1961p
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Re: Comet C/2011 L4 (PANSTARRS) [Re: BrooksObs]
      #5666105 - 02/06/13 09:57 PM

What magnitude was hale-Bopp or hyakutake?

?

Pete


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BrooksObs
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Reged: 12/08/12

Re: Comet C/2011 L4 (PANSTARRS) [Re: azure1961p]
      #5666184 - 02/06/13 10:44 PM

Quote:

What magnitude was hale-Bopp or hyakutake?

?

Pete





At their peaks, -0.5 and 0.0 respectively.

BrooksObs


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azure1961p
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Re: Comet C/2011 L4 (PANSTARRS) [Re: BrooksObs]
      #5666193 - 02/06/13 10:48 PM

Ok - thanks.

Still 2+ is impressive in my book. Very-good is entirely acceptable . Frankly anything brighter mag 6 to me is good so this ought to be refreshing.

Pete


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pogrzex
member


Reged: 01/25/13

Re: Comet C/2011 L4 (PANSTARRS) [Re: azure1961p]
      #5666392 - 02/07/13 02:17 AM

Quote:

What magnitude was hale-Bopp or hyakutake?





What significance does it have? They were visible on dark sky easily with naked eye. There is no chance to see +2 mag object with naked eye so low over the horizon + on so bright sky. To me it's no comparison!

Edited by pogrzex (02/07/13 02:17 AM)


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