Comet C/2011 L4 (PANSTARRS) - Bright in 2013?

[mithrandir (Andrew)]

Originally Posted by ngcles

Subject to correction here, but I don't think we even know whether this is a "first-timer" (notorious underperformers) or a "return-visitor".

Les, my understanding is that unless the eccentricity drops it will be a one-timer. MPEC say 1.0 but that is rounded. JPL has had 1.0004 or higher ever since they dropped the warning about limited observations.

Once e is established to be below 1.0 don't they relabel C/ as P/ ?

Andrew

[ngcles]

Hi Andrew,

Originally Posted by mithrandir

Les, my understanding is that unless the eccentricity drops it will be a one-timer. MPEC say 1.0 but that is rounded. JPL has had 1.0004 or higher ever since they dropped the warning about limited observations.

Once e is established to be below 1.0 don't they relabel C/ as P/ ?

Andrew

Not certain as to when they re-designate Andrew but with the orbital elements jumping around quite a bit until a longer track is observed it's
probably too early to say with great certainty.

True, e=1.0 at the moment (so the orbit appears parabolic implying a once-only pass) but figures might change so we'll know more certainly whether it is a first-timer or not in a few weeks I guess.


Best,

Les D

[Greg Bryant]

If the comet's orbital eccentricity (e) is less than 1, then it is a (long or short) periodic comet. However, the designation "P/" is only applied to comets of period 200 years or less, and of late there's been a trend to only apply "P/" straight away if the comet is of period 30 years or less, with the "P/" only being applied to comets of 30-200 years when it is sighted again at the next return.

The Minor Planet Centre's orbit for PANSTARRS has e=1 because they solve for e=1 at this time until sufficient observations are available (thus far, the observations still only go up to June 11). The JPL orbit is derived from the Minor Planet Centre's database of reported observations but makes different assumptions.

Greg

[ngcles]

Hi Greg,

Originally Posted by Greg Bryant

The Minor Planet Centre's orbit for PANSTARRS has e=1 because they solve for e=1 at this time until sufficient observations are available (thus far, the observations still only go up to June 11). The JPL orbit is derived from the Minor Planet Centre's database of reported observations but makes different assumptions.

Greg

Thanks for that -- without knowing the answer, I had a sneaking suspicion that the e=1 was an assumption used in the early orbital calculations and that more observations eventually provide the true figure. Thanks !


Best,

Les D

[Outbackmanyep]

We still have a while to wait until we can "predict" the end result, comets can do anything! My job, though, will be to start observing when it's in range of my 10" visually.

[Greg Bryant]

That will be in about a year. PANSTARRS should be around 13th magnitude mid next year.

Greg

[luigi]

This comet needs a better name, I can imagine press editors horror to title "Look for PANSTARRS in your night sky"

Mmmmm....

[ngcles]

Hi Luigi & All,

Originally Posted by luigi

This comet needs a better name, I can imagine press editors horror to title "Look for PANSTARRS in your night sky"

Mmmmm....

Yes I can see this one being nick-named "Comet Pornstar" -- particularly if it becomes a spectacular performer.


Best,

Les D

[Alchemy (Clive)]

Originally Posted by ngcles

Hi Luigi & All,



Yes I can see this one being nick-named "Comet Pornstar" -- particularly if it becomes a spectacular performer.


Best,

Les D

Doh...... It's kinda obvious once it's pointed out..... What were they thinking when they picked that acronym.

[ngcles]

Hi All,

Another set of elements incorporating observations up 'till up to 1 July has seen the date of perihelion jump around again (backward by 2-odd weeks) -- now on 8 March 2013 as opposed to the 25th March. Also the orbital inclination has changed a bit (10-odd degrees) from the last set

Expect further change ...

From MPEC 2011-N13 Issued 2011 July 2, 21:04

C/2011 L4 (PANSTARRS)
T 2013 Mar. 8.82253 TT MPC
q 0.3006310 (2000.0) P Q
Peri. 333.66728 +0.41661800 +0.08460732
Node 65.73753 +0.90483995 +0.05747651
e 1.0 Incl. 83.13473 -0.08771602 +0.99475527
From 131 observations 2011 May 21-July 1.

At least this set sees the comet at its best in the evening in a dark of the Moon. But there will probably be further alteration as time goes on so ...


Best,

Les D

[CometGuy]

Hi Les,

I believe the last set of elements published in MPEC 2011-M31 to be erroneous. This was noted by a number of people in one of the recent comet lists. Apparently, the elements are auto generated now, so something must have gone amiss.

Interesting when I use the same astrometric sets I have consistently being getting perihelion around March 11 from the past 2 weeks so wonder if there is still a minor problem with the elements given in the recent circular. In any case it does make too much difference in viewing circumstances.

Terry

[universe24 (William Chin)]

Has anyone got the visual through telescope or imaging results of the current status of the comet?

Thanks.

[Liz]

As far as I know, it hasnt been visible for as while, but should return to our morning skies in the next week or so.

Outbackmanyep had a go this morning but no luck yet.

[universe24 (William Chin)]

Thanks on the reply.

The observation of this month and next month is important to ensure that the comet is going well for the show in March 2013...

[Liz]

No worries William ... am sure we will have reports coming in over the next couple of weeks, fingers crossed, will be very exciting!!

[mithrandir (Andrew)]

The latest set of elements from MPEC 2012-W54 are:

C/2011 L4 (PANSTARRS)
Epoch 2013 Mar. 9.0 TT = JDT 2456360.5
T 2013 Mar. 10.16768 TT MPC
q 0.3015428 (2000.0) P Q
z -0.0001128 Peri. 333.65151 +0.41006822 +0.10046896
+/-0.0000009 Node 65.66583 +0.90783010 +0.05059188
e 1.0000340 Incl. 84.20690 -0.08768448 +0.99365308
From 1290 observations 2011 May 21-2012 Oct. 1, mean residual 0".4.

I've run all the reported data from MPEC through find_orb and get much the same.

C/2011 L4
Perihelion 2013 Mar 10.160686 TT = 3:51:23 (JD 2456361.660686)
Epoch 2012 Aug 18.0 TT = JDT 2456157.5 Earth MOID: 0.6682 Ju: 0.0467
q 0.3015788883 (2000.0) Me: 0.0120
M(N) 4.9 K 10.0 Peri. 333.64584969 0.41005300042 -0.10051188149
Node 65.66606199 0.90782756215 -0.05068004038
e 1.0000681616 Incl. 84.20719178 -0.08778185563 -0.99364424977
From 1294 observations 2011 May 21-2012 Oct. 1; RMS error 0.580 arcseconds

The doco is a bit hard to make sense of but I think that is predicting a nuclear magnitude about 4.9

[cometcatcher (Kevin)]

This comet is only just barely above the tree line after Christmas for me. Not good considering Mackay skies at that elevation during summer. Why couldn't it have been a winter comet?

[universe24 (William Chin)]

Originally Posted by cometcatcher

This comet is only just barely above the tree line after Christmas for me. Not good considering Mackay skies at that elevation during summer. Why couldn't it have been a winter comet?

A winter comet still awaiting you and other fellows to discover one

I will try to observe it near equator on 22th Dec.

[Rob_K]

Hi William. It's back and going OK. Managed to image this comet at very low altitude in a fast-brightening sky this morning. Trailed a bit but nonetheless the comet is clearly visible. Position should improve day by day until the Moon kills it.

I added some star magnitudes to the image, TYC and rubbery. The comet definitely appears brighter than mag 10, how much brighter is difficult to say because any extended coma would have been washed out with the sky brightness, other factors aside.

http://i727.photobucket.com/albums/w...ec2012text.jpg

Cheers -

[cometcatcher (Kevin)]

Well done Rob!