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Old 26-12-2011, 09:12 AM
luigi
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Originally Posted by swannies1983 View Post
Dramatic drop in brightness? Damn. Adelaide's weather will be fine from wed onwards, with a chance it will be clearish tomorrow. Hopefully the tail doesn't fade too much.
I didn't notice a dramatic drop. The tail it's very very easy to see with the naked eye from rural areas. In fact rural people point to it asking what the thing is. Looks like the beam of a reflector but it curves up.
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  #282  
Old 26-12-2011, 09:23 AM
swannies1983 (Dan)
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No worries. I was just going by Liz's comment http://www.iceinspace.com.au/forum/s...&postcount=277

I had been following this prediction http://www.iceinspace.com.au/forum/s...67&postcount=5 so didn't expect a large drop in brightness yet.

I was able to see Lovejoy a couple of times last week but clouds have spoilt the show for the last few mornings. I might be able to borrow a better camera tonight. I now also have a tripod (dad found one at his house), so i don't need to support the camera on a pillow on the top of my car
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Old 26-12-2011, 09:28 AM
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I'm with Ian. Went to bed to clear skies. Up at 2:00 to drive somewhere with a good horizon.

A solid cloud band about 25 deg high lay along the eastern horizon. Occasional stars were peeping through to the NNE keeping up hope, but I gave up around 3:45 with twilight approaching.

At least I saw a bit of it from home on Xmas Day thought the Sydney light pollution.
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Old 26-12-2011, 09:31 AM
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Tail Brightness

Hi Luigi and Swannies,

we should expect an aparent drop of in brightness as the comet approaches perigee. With the increase in not only length, but width as well, the light is spread over a greater area and therefore gives the impression of being fainter.

Having said that there is also the decreasing amount of volatiles coming from the central condensation as the comet backs away from the sun that has a great impact on the appearance of Lovejoy now compared to five days ago.

Luigi is right regarding the urban vs rural view. The rural view is best, but my mate George Ionas who lives on the south eastern side of Palmerston North (population 80,000) saw the comet from his backyard this morning after the cloud that took me out cleared in his vicinity. So, there is still hope for city dwellers who minimize their light pollution problems as much as possible.

The only photos that I have seen from this morning suggest that the light along the tail is fairly evenly bright. Which was my impression too yesterday.

Cheers, Coops.
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Old 26-12-2011, 09:39 AM
swannies1983 (Dan)
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Thanks Ian. I certainly understand some of the factors contributing to differences in brightness. This is one reason why I travel about 20mins to get to a relatively dark spot.

I know the comet will fade but I was under the impression that it would still be fairly easy to see at least for a few more days.
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Old 26-12-2011, 10:27 AM
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Originally Posted by swannies1983 View Post
I know the comet will fade but I was under the impression that it would still be fairly easy to see at least for a few more days.

I dont think I will be able to see the comet again , I think I need to rest tommorrw am, but I did think the drop in brightness over the last 2 days was quite a bit. Still, perhaps my eyes are not as good as used to be.

2 days ago it was stunning from the dark site, today was .... ah, where is it?? Just me.

Good luck, but make sure its tomorrow am, time is running out.
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  #287  
Old 26-12-2011, 10:49 AM
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Agree with Liz and Ian...although my last view was 3 days ago, had to take some time out for xmas duties (damn).

Anticipating the drop off I drove out north of Esperance yesterday. Other than some airglow to the south (over the ocean), the sky was clear and very dark.

Attached taken just before onset of astronomical twilight 26-Dec-2011 (AWST) with 14mm, @ iso 3200, f/2.8, 25s

Nice to also get some zodiacal light + ISS in the same shot.

Will stay another couple of days...even without the comet it's nice to get away from those darn city lights.
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  #288  
Old 26-12-2011, 11:11 AM
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i note many saying the comets tail is dropping off in intensity, and that may likely be the case for all i know, not having seen if for some days, .. but may be worth noting that, at least when i was still a cometchaser, it was often remarked on well known phenomena that comets appeared to dim when passing through milky way (in front of), (du to loss of contrast) and then people spoke of sudden (apparent) brightening once out the other side, altho that was usually in reference to less spectacular comets .. must be a factor in dimming just the same, even if is truly dimming

Colin, that is amazing all those sky (and space) phenomena in one pic - you have my vote!

Last edited by fringe_dweller; 26-12-2011 at 01:07 PM.
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Old 26-12-2011, 11:21 AM
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Ian those shots of W3 with the cabbage trees are truly retro, nostalgic of older famous comet shots for me, bit like the techpan and schmidt cameras are, cheers
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Old 26-12-2011, 11:33 AM
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as to interesting 'two tails' i dont know answer to that, i even visited my old virtual hangout - comet central - comets_ml to see if there was answers there from the many knowledgeable experts, after short search i couldnt find one!? but i suspect? it is something to do with parabolic hood of dust tail seen in early pics http://www.sott.net/image/image/s4/89554/full/ebr.jpg creating effectively two tails, so material releasing jet(s) are on sun facing side of comet, creating an apparent gap behind .. i read here the tail is pointing towards earth at the moment, from our perspective, ... also in a weird way.. and its only my weird take on it tails also appear to cross over each at some point, not unlike the intersecting meeting points of a venn diagram lol - my expalnation is probably way off, anyway i tried to make sense of it
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Old 26-12-2011, 11:44 AM
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North West Tasmania?

Having been out at 5.15 on Xmas morning then 4.30 today I have been disappointed to find nothing of Lovejoy in the sky.
Any reason I shouldn't be able to see it from just 300kms south of Melbourne??
Hope everyone who celebrates Christmas had a happy and joyful day.
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  #292  
Old 26-12-2011, 12:02 PM
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Trevor, you need to get out around 2:30am to see the comet in its glory. It's best around 3-3:30am and onto about 4:15....just before the sky starts to brighten too much. 15 mins can make a big difference as to whether you see it at all. Also, make sure you have a clear sky and try to get away from town lights. Look about halfway down the back of Scorpius and to the lower left of the pointers. You'll see it.....it's unmistakable
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Old 26-12-2011, 12:09 PM
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My image from this morning, and maybe my last as cloud from Cyclone Grant is about to descend, and the comet tail fades, but what a wonderful journey it has been!!
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Old 26-12-2011, 12:53 PM
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Hi Colin,

that is the image I have been waiting for this morning since I missed out. The only other shot I've seen has probably clipped the end of the tail. You didn't by chance take anything more zoomed in?

You haven't exactly missed much in that one shot!

Kearn,

regarding the two tails, perhaps the analogy that often comes to mind with substantial comet tails like this one is the 'twisting ribbon effect.' There can often be two jetting points emerging from the comets nucleus. Each sends out a stream as the nucleus rotates. The twists spiral out and away from the nucleus over the coming days.

The initial split that everyone has seen is now well up the tail, and looking at Colins latest pic it has almost reached the end. To make that point clearer I've attached a shot of Hyakutake by my mate Noel Munford on March 22nd, 1996. Taken on a 50mm lens at f/2 Fuji P800 film 25 seconds. You can clearly see the split in the tail above the bright star (Arcturus). In my shot of Hyakutake from March 23rd, 1996, taken with Nikon and an f/1.4 50mm lens, 25 seconds on Konica 3200 film, the two threads have now twisted ribbon like. The K3200 is a lot more grainy than the P800, but you can see how one thread loops up and over towards Arcturus from the coma before diving back across the seemingly straight thread, then underneath to re-emerge.

The drawing attached is one that I did for a talk on this great comet and better shows the ribbon effect. The drawing also shows the actual length better compared to the photo.

I hope that helps.

Coops

BTW the end of the tail is now circumpolar from my place (40 south), and even though it will be running almost horizontal along the horizon I might give it a go after astronomical twilight ends (around 10.30 p.m. N.Z.D.T.)
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Old 26-12-2011, 01:10 PM
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I like that explanation on morphology Coops! make good sense ah yes, great comet bright tail rising first in dark skies - at that stage with head below horizon sure had shades of B2 for us also ah memories
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Old 26-12-2011, 01:25 PM
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Quote:
Originally Posted by Ian Cooper View Post
BTW the end of the tail is now circumpolar from my place (40 south), and even though it will be running almost horizontal along the horizon I might give it a go after astronomical twilight ends (around 10.30 p.m. N.Z.D.T.)
cool! like a giant sky clock it will always be Comet time!
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Old 26-12-2011, 02:31 PM
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now i remember my comets 101 a little better Coops! i also now remember the other old analogy ( for sunward facing jets) of the lawn sprinkler hehe albiet a very slow or stuck one in this case

Comet 2000 WM1 (LINEAR) another dust comet, on a much smaller scale,, had similarities back in jan/feb 2002 during outburst - Michael Mattiazzo has some great images of jet activity , of WM1 at that time, that might help with conceptualising similar morphology in Comet Lovejoy for some who may be new to this stuff, and getting head around it .. altho in WM1's case it was more side on view at that time, rather than this perspective of from behind we are experiencing with C lovejoy

http://www.yp-connect.net/~mmatti/images/wm1jan31.jpg
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Old 26-12-2011, 03:05 PM
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27 degree tail

The naked eye tail on Comet Lovejoy was about 27 degrees long this morning. The comet was brighter than the Norma star cloud.
I observed it from Gibraltar Rd Clifton (elevation 690m) about 36km west of Tenterfield NSW.
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Old 26-12-2011, 03:32 PM
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Tail out to 28.5 degrees this morning

Hi Kearn,

yes I remeber WM1 well. Those two links are great too.

You may remember the picture attached of WM1 that I took with the 400mm at f/6.3, Fuji P800 for 15 minutes from memory. This is closely cropped but shows the start of the Ion Tail snaking across in front of the two dust streamers.

With reference to Glenc's comments on the tail length I plotted the tail from Colin Legg's fine shot this morning and measured it out to 28.5 degrees. So she is still climbing as expected.

I made up a background chart from The Sky 6.0 programme. Turned it into a B&W negative, then penciled in the comet from photos we have taken this week, Colin's being the clincher. Re-scanned that and reversed it back ito a B&W image. This quite dramatically shows how the tail is growing as it comes towards us.

For tonight, and tomorrow morning the end of the tail will be against the dark of the Emu's neck which should improve the contrast immensely.

Cheers

Coops
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  #300  
Old 26-12-2011, 03:58 PM
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I do indeed remember that fine shot yours Coops, good time to bring it out! love that chart too, it has helped me visualise progress a lot cheers

27 visual, 28.5 deg photographic tail!
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