ISON Interactive Model

[czokletmuss]

Check this out, you can find here pretty cool visualization of ISON orbit.

Edited November 12, 2013 by czokletmuss

[Tommygun]

Closes approach 26 Dec, that's a great cosmic Christmas present.

I see it passes by Mars at 10 million Km, that's one impressive view.

I wonder if Mars will get a good meteor show out of it?

Although it looks like it is coming in high over the planetary plane at that point.

[PakledHostage]

The Comet Ison Observing Campaign group has a nice website detailing scientific efforts around the world to observe Ison. Their site includes a light curve that is updated every two or three days. The plot below is the most recent update from November 11th:

[czokletmuss]

Great link PakledHostage, thanks!

[Lexif]

The light curve image doesn't seem to load currently. I guess it's still too early for naked eye sightings? We might have good weather tomorrow morning, which is rare in November. The Moon seems OK, too, so I thought I might try to take a picture of it. But I'm not confident, it tends to be foggy here in the morning and the comet is now very low above the horizon. I might have to wait until it returns on the evening sky.

About the Mars flyby: The observation calender on the Ison Campaign Group site shows extensive observations by MRO and Mars Express about 6 weeks ago. I was able to find some disappointing images from MRO, but nothing from Mars Express yet.

I also learned from the calendar that MESSENGER will observe ISON from Mercury, and of course SOHO and the STEREO probes also got their eyes on it. I think it's mindblowing that we are able to observe a comet from 3 different planets and from earth orbit on the opposite side of the sun (STEREO) as it passes by.

[PakledHostage]

I guess it's still too early for naked eye sightings? We might have good weather tomorrow morning, which is rare in November. The Moon seems OK, too, so I thought I might try to take a picture of it. But I'm not confident, it tends to be foggy here in the morning and the comet is now very low above the horizon. I might have to wait until it returns on the evening sky.

It may be a bit early but you never know. You might be able to capture it with a decent camera. If you do manage to photograph it tomorrow, would you be willing to post your picture on these forums? I'd be interested to know what settings you used. I have a potential weather window on Sunday morning. If it still looks promising on Saturday, I may even try to borrow a friend's Canon 6D. It is a good low light camera and will give me my best chance of getting a picture.

[Lexif]

I will post it here, of course. I plan to use a Canon EOS 1000D with the cheap EF 50/1.8. I once took a picture of Orion with it where the dimmest stars were around 13.5 mag, and that was from my window in the city. I had to stack 30 to 50 five second exposures and about a dozen darkframes. So I should be able to spot it using this technique. Maybe I will try my tele-zoom, too, but it doesn't have a good apperture.

At 6:20, the beginning of nautical twilight, the comet will be about 20° above the horizon, while my local eastern horizon is about 10--15° high, so it should be possible if it's not foggy. But guess what's predicted for the morning?

Edited November 14, 2013 by Lexif
typo

[Motokid600]

Three nights I've tried to find it in my 11" CPC. No luck. I'll get it though. I can hook up my Canon rebel to it too so hopefully it reveals itself before it gets to close to the sun.Too much haze in the morning. Might have to wait until its in the evening. By then it will have exploded in brightness or just.. exploded lol. Which is my bet. With a 750k mile periapsis I dout ISON will hold together. We may get a line of comets instead. Which might be just as cool if there bright.

[PakledHostage]

Three nights I've tried to find it in my 11" CPC. No luck.

I was going to try tomorrow morning. My weather window has moved up from Sunday morning. I hadn't actually considered image stacking as an option, but I did some practice image stacking last night after Lexif mentioned it. I didn't have much success; I get better images with a fast prime lens and a high ISO. I will try both methods tomorrow morning. It looks like it is brightening nicely, but I may not get another chance to see it until after perihelion because the local long range weather forecast doesn't look promising for astronomy.

Articles that I've read (such as this one in "Nature") indicate that ISON is large enough that it won't be vaporized and predict that ISON will survive perihelion. Below is the most recent light curve from the Comet ISON Observing Campaign group:

[Lexif]

Over the weekend, we will be more or less fogged in here in central germany, at least in the morning. Friday morning, I couldn't even the the house across the street. It's a bad time of the year for astronomy here. I guess I have to wait until it's past the sun.

Edit: About the stacking: I just tried it twice -- I don't do astro photography frequently. This is my result for Orion from a series of about 50 images with a 50/1.8 on a Canon 1000D at 5s/2.2 aperture/ISO 1600 with about 20 dark frames. Conditions were not good and it was just an experiment from my window in the city.

http://imgur.com/a/zb3CQ

The other picture is a raw light picture. Don't know if I could have done something to get the final result less blurry.

Edited November 16, 2013 by Lexif
added stuff about stacking

[K^2]

I'll see if I can catch a glimpse of it through a small telescope. Naked eye is out of the question from a city, but I should be able to see a mag 6 easy enough if the weather cooperates. Got to be up before 6am, though. Ugh.

[PakledHostage]

I managed to photograph ISON this morning. It isn't very big (including the tail, it is smaller than the full moon) and I couldn't see it with the naked eye, but I didn't need a telescope or long lens to get it. I did have to stack 70 images (1 second exposures at f/2.0, ISO 400) for it to reveal itself. I probably would've been better off if I'd been able to get up before twilight and if I lived in a drier climate.

Even so, I thought I'd share the cropped and annotated image:

Edited November 17, 2013 by PakledHostage
fixed a spelling mistake

[K^2]

I was hunting it in the morning as well, but it was a bit hazy in the eastern sky. I managed to get a solid fix on Spica, γ, and θ Vir. By eye, I could just barely make out γ with the edge of my vision. And I think I was able to just see 49 Vir through the telescope, but your picture clearly shows that if I could barely make out 49 Vir, I had no hopes of seeing ISON. Tonight looks like it will be even worse, but maybe I'll get lucky in the next few days. With a clear sky, I should have no trouble spotting it.

By the way, what do you use for stacking?

[PakledHostage]

By the way, what do you use for stacking?

DeepSkyStacker. It is free and claims to have an intuitive UI. It works OK despite its quirks.

[Lexif]

Well done! What focal length is that, about 250 mm on a crop camera?

[PakledHostage]

Well done! What focal length is that, about 250 mm on a crop camera?

I used the same 50mm lens that you mentioned earlier in this thread. The camera has a ~20 MP APS-C sensor, for a crop factor of 1.6 (i.e. 80 mm effective focal length).

I only posted the portion of the image that I thought was relevant. I did not resize it. If I get another chance to get out before perihelion, I will use a longer lens.

Edited November 17, 2013 by PakledHostage

[PakledHostage]

November 25th update from the Comet Ison Observing Campaign group:

Reports of dramatic changes in comet ISON's dust and molecular emission rates may possibly be an indication that the nucleus has disrupted. We may not know for sure until ISON reaches (and hopefully) passes perihelion, though complete disruption - if that is indeed the case - would lead us to think that survival may be unlikely. In [two] days' time, we'll know...

Edit: I also found a GIF on the ISON observing group's website showing ISON and Encke as seen from NASA's STEREO spacecraft. Mercury is the bright fixed object at upper left and the Earth is fixed at centre right. ISON is the larger comet and Encke is the smaller one.

[image Credit: Karl Battams/NRL/NASA/CIOC]

Edited November 26, 2013 by PakledHostage

[Scotius]

So, soon we should know if ISON survives perihelium or not. I hope it will Last great comet visible from my country was over a decade ago. Time to refresh memory

[KerbMav]

Weather is a bitch - and living surrounded by hills in a river valley sucks - but I possibly wouldnt know where to look anyway, I only ever manage to identify the big wagon - which is called Big Dipper in English as I just learned/googled!

[PakledHostage]

but I possibly wouldnt know where to look anyway, I only ever manage to identify the big wagon - which is called Big Dipper in English as I just learned/googled!

It is too close to the Sun right now to see it anyway. Perihelion is at about 1800 UTC tomorrow.

And mods, is there any chance that Lohan2008's new ISON thread could be combined with this one? I imagine that both threads will have some life left in them if ISON survives perihelion to fly over the Earth in late December.

[K^2]

Edit: I also found a GIF on the ISON observing group's website showing ISON and Encke as seen from NASA's STEREO spacecraft. Mercury is the bright fixed object at upper left and the Earth is fixed at centre right. ISON is the larger comet and Encke is the smaller one.

http://www.isoncampaign.org/files/images/blogpics/ison_encke_nov19_23_crop_hi1a.gif

[image Credit: Karl Battams/NRL/NASA/CIOC]

I have to ask a potentially stupid question. Are we actually seeing solar wind on this image? Looks too persistent to be just noise, and direction matches, but does it really have sufficient density to be visible? Or does the choice of spectrum have something to do with it?

[PakledHostage]

Are we actually seeing solar wind on this image?

I was wondering that too.

Here's another image from the STEREO-A (Ahead) probe. According to the image caption at Universe Today:

Comet ISON joins Earth and Mercury in this photo made by NASA’s STEREO-A (Ahead) spacecraft in the early morning hours of Nov. 23, 2013. The sun is off-frame to the right

[Lexif]

NASA's astronomy picture of the day page says it's the solar wind.

http://apod.nasa.gov/apod/ap131123.html

From what I found this clip was taken with the heliospheric imager (HI), which appears to be a visible-light device. I would guess it should be possible to see the solar wind as an extension of the sun's corona. (The corona is what you see in a total solar eclipse.) Isn't at least one component of the solar wind just the molecules of the coronal gas that are on the fast end of the velocity distribution so they reach escape velocity?

[K^2]

Corona is easily visible because it has peak luminocity in visible band. By the time solar wind reaches Mercury, peak wavelength from thermal radiation should be in the 2-5μm range. I can't imagine it being luminous enough in visible band to be picked up by detector. I can be wrong about that, but I would need to see a source. I would be more willing to believe that it's a scattering or even refractive effect.

[PakledHostage]

Corona is easily visible because it has peak luminocity in visible band.

And also because the light comes on when I open the fridge door...