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Alrighty, thanks for the advice. Looks like it's going to be cloudy this evening but I'll give it a tonight/tomorrow if it isn't. If it is, might just pack up the sky-viewing equipment and head outside the city instead.
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| # ? Mar 15, 2013 21:31 |
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| # ? May 25, 2013 02:37 |
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So, just to post an update on Comet ISON. It's still developing nicely, and now has a short dust tail that is beginning to show up in long-exposure photographs. It is currently a little over 4.5AU from the sun, which is slightly inside of Jupiter's orbit. The true test of whether or not the comet will be truly great is when it starts getting around the vicinity of Mars's orbit. Usually first-time Oort Cloud comets have a layer of volatiles that make them appear brighter than older comets at the same distance, but that is usually depleted by the time they get to about Mars's distance from the sun. The end result is that they stop brightening as rapidly, and actually begin to underperform as compared to older comets. One interesting thing to consider is Comet ISON breaking up near perihelion. This would multiply the surface area for sunlight to bake off, and we'd see a rapid brightening as a result. Part of the reason that legendary sungrazing comets like the Kreutz group comets appear so bright post-perihelion is because their nucleus fragmented during the encounter with the sun. Anyway, we'll start getting a real idea of how ISON will perform in November starting sometime in early July. Also of interest is a relatively close approach to Mars (~6.5 million miles) on October 1. Not sure how bright it will appear there, but considering it's still inbound, it likely won't be extremely spectacular. Might be a good target for Curiosity's cameras though, since it's got the capability to image targets at night.
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| # ? Mar 15, 2013 23:04 |
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Venusian Weasel posted:Hey, I wrote an article about that on Zero Gravitas's site, Astronomy Aggregator! That was a couple weeks ago, and some new observations have been found, which bring the chance of impact down from 2% to 0.08%. Since then we've figured out some more of the geometry of the comet's pass - it'll be along the Martian night-day line, so it'll be an impressive site from sunset until around Martian midnight, or longer if the coma's large. A meteor shower is unlikely to happen, large particles won't have traveled far enough to get to Mars. Current closest approach is about 57,000km, unlikely to change a lot from that. It's honestly a shame that C/2013 A1 probably won't hit Mars. While Curiosity and the orbiters would be lost, the follow-up missions would return an unimaginable level of scientific data. Exploring a fresh impact crater might even be the impetus for a manned mission, once the surface conditions settle down a bit. It would take decades to centuries for Mars to return to 'normal' giving plenty of time for all sorts of missions to be sent. Even a close pass is going to be pretty amazing - at 57k km the MRO's HiRISE should get some spectacular images of the comet body itself. MAVEN's instruments should be pretty useful at going after the tail environment as well. It's like getting another Halley Armada for free!
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| # ? Mar 16, 2013 02:14 |
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Devyl posted:Pretty sure I got it. Unfortunately I didn't have my tripod on hand before I got kicked off the top of the building I was shooting from. I'm in Mississippi: These are pretty close to what I've been seeing for the past few days in DFW - but there's always a half dozen airplane contrails surrounding it so I haven't been sure.  In these sky maps people are posting - is 30 minutes after sunset applicable to every latitude? And what time should I expect the comet to set below the horizon?
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| # ? Mar 16, 2013 19:38 |
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Did you guys know that Brain May, lead guitarist from Queen, was working on a PhD in Astrophysics at Imperial College London when Queen got big, and that he finished his thesis over 3 decades later, in 2007? It was entitled A Survey of Radial Velocities in the Zodiacal Dust Cloud. He even managed to co-author 2 research papers during the Queen era: MgI Emission in the Night-Sky Spectrum in '72 and An Investigation of the Motion of Zodiacal Dust Particles (Part I) in '73. I guess he's currently Chancellor of Liverpool John Moores University, and he even has an asteroid named after him, 52665 Brianmay. Here's his Wikipedia page from which most of this info was stolen outright: http://en.m.wikipedia.org/wiki/Brian_may#section_8
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| # ? Mar 16, 2013 19:44 |
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edit: Hah, that's awesome! I'm impressed. Randandal posted:In these sky maps people are posting - is 30 minutes after sunset applicable to every latitude? And what time should I expect the comet to set below the horizon? I just looked up the view for Dallas tonight, sunset is around 7:35 and the comet will likely be below the horizon around 8:30. If you have a compass app on your phone (or an actual compass!  ) at 8:01pm it will be around 277° (west) and around 10° altitude which you can determine in this helpful way that Venusian Weasel pointed out:Venusian Weasel posted:Hold your fist at arm's length - that's 10 degrees. I keep hearing that it's getting fainter now so you may need binoculars to see it, hopefully you're able to! PREYING MANTITS fucked around with this message at Mar 16, 2013 around 19:54 |
| # ? Mar 16, 2013 19:52 |
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This is pretty cool. It's a time-lapse video taken by the STEREO observatory of PANSTARS: http://www.youtube.com/watch?v=reizDW0Y-Rk The Sun is off the screen to the left. The two dots are Mercury, left and Earth, right. The stuff streaming out from the Sun is the solar wind, with some significant coronal mass ejections visible. The CMEs appear to miss the comet, apparently being above or below its orbital plane. We're seeing 3D projected into 2D, so we lose the depth.
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| # ? Mar 16, 2013 20:04 |
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PREYING MANTITS posted:
Thanks!! If I don't see it while at work (I drive) tonight I'll be heading up to Oklahoma on my day off tomorrow to get away from light pollution.
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| # ? Mar 16, 2013 21:25 |
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Bloody hell. What a gem of
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| # ? Mar 16, 2013 21:29 |
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Randandal posted:These are pretty close to what I've been seeing for the past few days in DFW - but there's always a half dozen airplane contrails surrounding it so I haven't been sure. At first it appeared to be a contrail to me as well. Seeing as how it was supposed to be difficult to see with the naked eye, I was surprised how well it was visible. I'll be heading out tonight to see if I can get some better pictures and not get kicked off the building this time.
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| # ? Mar 16, 2013 21:34 |
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Michael Jäger, an extremely skilled comet photographer, posted a picture of PanSTARRS that he made last night. It's hands down the best ground-based picture made yet. Another astrophotographer, Peter Rosen, apparently has images that show PanSTARRS has fragmented. (See the picture on Spaceweather.com here) The secondary condensation that shows up in his photos isn't present in any other photographs I've seen, though. Weird. Good luck with observing the comet tonight, guys, I'm clouded out again. Hopefully I'll be able to provide my own impressions of the comet again starting Monday evening.
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| # ? Mar 17, 2013 01:17 |
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Here are two pics I grabbed on my hike the other day. I am confounded about not being able to see it. Maybe it was too bright still, before I gave up? I should think my latitude meant I would be darker than many other places that could see it, perhaps it's there yet, perhaps I'll be luckier next time. On the 13th.  No regrets. I'm happy with my local geography. Cloudy forecast ahead, go on Ison. By the way, if you are interested in seeing a total solar eclipse, Wikipedia is absolutely amazing on this: http://en.wikipedia.org/wiki/Solar_eclipse Scroll to the bottom and find the lists, you can plan the nearest totality holiday for any given point in the rest of your life.
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| # ? Mar 17, 2013 02:05 |
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Ola posted:Here are two pics I grabbed on my hike the other day. I am confounded about not being able to see it. Maybe it was too bright still, before I gave up? I should think my latitude meant I would be darker than many other places that could see it, perhaps it's there yet, perhaps I'll be luckier next time. It's actually kind of faint, and it doesn't really *pop* until the sky starts getting really dark. It's not going to be something you can go out and look at right after the sun sets. Most astronomy websites (and even a couple posters here) have been saying they could see it 30 minutes after sunset, but the earliest I was able to find it was close to 45 minutes after sunset. I guess part of it is dependent on the sky quality where you live. Also, I'm currently living in a small triangle of land where I would theoretically be able to see the eclipse of 2018 and 2024 without having to go anywhere! Too bad I won't be living here when that happens. Might come back to the area to see them if the weather looks good though.
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| # ? Mar 17, 2013 02:13 |
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I did wait for quite a bit, these are just the prettiest pics. If you look at the clouds on the horizon you might imagine that when the sight came into visibility, it was behind the clouds. That's my consolation at least, that cold hurt! The hike did me good though. Need to do more of them in winter, to keep the bloat at bay.
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| # ? Mar 17, 2013 03:09 |
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I saw it tonight. It was just naked-eye visible after 7:30 (local sunset at 6:45) as a very dim speck, but it was still in the band of light sky at that point so even in my (bad) binoculars only the nucleus was visible. Shortly before 8:00, with the horizon nearly dark, the coma was apparent in the binoculars in a "this is probably a comet" kind of way, and the whole shebang was faint but visible in my little telescope with a narrow-field eyepiece. The moon was also bright enough to cast shadows even though it was only a crescent, so that might have made it a little harder to see. Latitude is 44.18664 deg. North.
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| # ? Mar 18, 2013 02:09 |
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Randandal posted:Thanks!! A West Texas dust storm foiled me. The comet will be gone by next Sunday, won't it?  
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| # ? Mar 18, 2013 09:22 |
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I've just had a string of bad luck. We've had several clear days, only to have a thin layer of clouds move in from the West right at sunset, obscuring everything. Several times I got out my binoculars with a sky full of stars over my head, only to have everything disappear in a grey haze toward the horizon. I don't think I'll ever get a chance to get a good look at it.
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| # ? Mar 18, 2013 14:29 |
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Success! Was great weather today, didn't hike up very far and it turns out that wasn't necessary. Finally caught it at about 20:25 local, about a fist's height at arms length above the horizon, a bit north of due west. Could see it with the naked eye when I knew what I was looking for. A tiny little dandelion seed on the sky. Feels great to not have missed out, hehe. No pics, as I broke my $12 eBay tripod the other day.
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| # ? Mar 18, 2013 20:04 |
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Probably the clearest night I've had since PanStarrs has been visible. It was faintly visible to the naked eye about half an hour after sunset, which is a lot earlier than I had been seeing it. I think the reason it was taking me so long to find it last week was because of clouds. There was about a 20 minute window where I could see the coma looking directly at it, and some hints of a tail when looking off slightly to the side. People may be able to see a little more than I do, I get even more nearsighted than my prescription when it gets dark. I took a few series of pictures so I could try some new techniques in bringing out some detail. I don't have spectacular images, but they do have a little bit more detail than I was able to get in single long exposures. Hopefully it'll be clear tomorrow night so I can make some adjustments. Tonight I borrowed a technique from the hardcore astrophotographers called stacking. Essentially, it's combining the data from multiple photos to increase the signal-to-noise ratio. You can also use multiple short shots to get the same amount of light as a single long shot, with the added benefit of avoiding trailing from Earth's rotation (and stuff trails a lot at 300mm). Here's a stack of 5 4-second long images. I did a few things to it in photoshop (like histogram stretching and unsharp masking) to try and pull out a little more of the tail from the twilight.  I also made a stack of 4 1-second long images, and that preserves the detail in the coma at the expense of seeing as much of the tail. This one also matches my visual impression through binoculars pretty well. A star-like coma, a kind of curved bright streak pointing away, and then a vague mist to the left of the coma.  Now that I'm figuring out how to do this kind of thing in photoshop I might go back and work on some of the pics I took last week.
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| # ? Mar 19, 2013 03:35 |
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those are great pics. Been lovely weather here since Tuesday of last week. Hoping I can get 1 more sighting in before it gets too far away.
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| # ? Mar 19, 2013 03:55 |
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Absolutely spectacular pictures from northern Norway, aurora, comet and meteor in one pic. Might not be a meteor though, with those shutter speeds it could be an airplane far away or something. More pics here: http://www.pentaxforums.com/forums/...ow-tonight.html
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| # ? Mar 21, 2013 11:47 |
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Looks like a meteor to me. Airplanes don't leave streaks that fade out on the ends like that. I got a new batch of pictures from the comet last night, still working on processing those and trying out different techniques to bring out some details in the tail (not having a lot of luck with it, though). Just an update on the comet, it's fading pretty quickly, partly because the tail is becoming more and more face on to us and lowering its surface brightness. The bright star-like coma is still present, but it too is fading and starting to become a little bit less condensed. I wasn't able to spot it with the naked eye, and the part of the tail visible in binoculars is getting shorter. The tail's still showing up pretty nicely in photographs, and I'll probably take another go at photography once the weather clears out (which is looking like Monday at the earliest. Spring weather's not good for astronomy.)
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| # ? Mar 21, 2013 23:00 |
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Definitely a meteor. Awesome pic. 
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| # ? Mar 22, 2013 03:42 |
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Just saw PANSTARRS again. Significantly higher in the sky (and a WNW versus due west) than a week and a half ago, but definitely dimmer too. Absolutely needed binoculars for sure. Mrs. Slidebite couldn't even pick it out with the binoculars even with my direction.
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| # ? Mar 24, 2013 03:21 |
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Yeah, it looks like our little friend is leaving. Found this on FB, taken in Macedonia. 4 sec / 560 mm according to the photographer. 
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| # ? Mar 24, 2013 16:49 |
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Wow I can't do anything like that with my $200 point and shoot  Here is what I did get though with a manual shutter speed (10 sec). Comet is pretty much dead center.  Also, here is Orion with Taurus, Jupiter and the Pleiades at the top right. 
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| # ? Mar 26, 2013 03:52 |
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Haven't been able to look at the comet for nearly a week, I've been dealing with rain and snow since last Thursday evening. Just as well, though, I was sick as a dog over the weekend, and I probably would have made things worse by going out and trying to get some comet pics. Anyway, I'll post some of the pictures I got last Wednesday. A combination of 3 one-second exposures, probably the closest approximation to what I saw in binoculars.  A combination of 5 four-second exposures. I lose a bit of the fine detail to trailing, but I pull out a little more of the tail from twilight.  And a nice wide angle view. I stacked 3 four-second exposures and did some cutting and pasting with different layers so that both the comet and the foreground were both sharp.  National Weather Service forecast is calling for 44% sky cover at sunset tomorrow, so I don't know if I'll be able to report in on its brightness yet. The full moon is also going to be an issue for the next couple of days, so even if I can still spot it in the night sky it's still going to be washed out a bit from moonlight. Judging from the rest of the forecast, it's going to be at least next week before it clears out again, so tomorrow's probably my last chance to get decent photos of PanSTARRS. EDIT (March 26): Comet wasn't visible to naked eye tonight, didn't really see much in binoculars either. Not sure if it's from the moonlight washing everything out but whatever the case the comet is a lot fainter than it was last week. Pictures aren't all that great either, there's not a whole lot of contrast between the tail and the moonlit sky. Close-up, did some stacking and contrast enhancement, still not a whole lot visible.  Wideshot.  Venusian Weasel fucked around with this message at Mar 27, 2013 around 03:40 |
| # ? Mar 26, 2013 05:32 |
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Great pictures! Here's a write up on Ison. It starts in the morning sky, grazes the sun on Nov 28th and moves into the evening sky in December. Could be amazing... http://waitingforison.wordpress.com/november-2013/
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| # ? Mar 29, 2013 12:50 |
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Ola posted:Absolutely spectacular pictures from northern Norway, aurora, comet and meteor in one pic. Might not be a meteor though, with those shutter speeds it could be an airplane far away or something. That appears to be what's called an "Iridium flare".
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| # ? Mar 29, 2013 14:00 |
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Well spotted, it definitely looks like one of those. A rather short line with fading brightness at either end. Here's a very detailed write up on Ison from NASA: http://www.nasa.gov/mission_pages/s...ursts/ison.html Includes animation of its orbit, a fuzzy picture of it and about fifty disclaimers. It might be daylight visible! But don't bet big on it...
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| # ? Mar 29, 2013 17:49 |
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ISON update. Looking a bit bad actually.quote:"The much hyped Comet ISON is not evolving in the fashion we had earlier anticipated. Rather than slowly but steadily gaining in brightness it has stagnated at basically near 16th magnitude for a couple of months now. After experiencing an interval where the coma's degree of condensation grew quite strong, the object threw out an unexpected strong but short tail that has persists right down to today. However, following this episode the coma subsequently faded, became less condensed and smaller, all bad signs regarding the "health" of the comet's nucleus. Whether ISON becomes a Great Comet next fall, or just another in a long string of Great Flops, is now much more a question than ever before." http://www.space.com/20367-comet-is...redictions.html
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| # ? Apr 21, 2013 14:47 |
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| # ? May 25, 2013 02:37 |
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Speaking of Comet ISON, Hubble took a look at it recently. One thing to keep in mind with ISON is that it gets extremely close to the sun, and if it holds together through perihelion, it will likely be fairly bright once it emerges into the sunset. Comet Lovejoy would probably be a pretty good analogue for ISON if it doesn't brighten as predicted - it'll go in 3rd or 4th magnitude, get baked by the sun, and come out -2 magnitude (but fading rapidly). It might not be comet of the century material if the brightness trend continues, but it could still put on a good show regardless.
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| # ? Apr 23, 2013 22:36 |
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