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Really close NEO 2012 DA14 Feb-15-2013

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#26 Centaur

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Posted 11 February 2013 - 03:17 PM

Whoops, Darren, I just realized you will not have the data in Solex for asteroid 2012 DA14. Aldo had e-mailed that to me.

For my location in Arlington Heights, Illinois on 2012 FEB 15, below are the asteroid's coordinates.

18:00 CST RA 13:10:35.2 Dec N 74° 13' 52"
19:00 CST RA 13:38:25.2 Dec N 78° 04' 24"
20:00 CST RA 14:10:01.9 Dec N 80° 44' 11"
21:00 CST RA 14:45:39.9 Dec N 82° 37' 17"
22:00 CST RA 15:25:02.5 Dec N 83° 57' 20"
23:00 CST RA 16:07:02.5 Dec N 84° 52' 58"

#27 Centaur

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Posted 11 February 2013 - 03:35 PM

I have a few questions regarding this near "hit" asteroid.

1. Is it just a matter of time that this asteroid missed us? In other words, does the path of this asteroid actually cross the path of where "we were" or where "we are heading" by about 15 minutes? Does Earth actually cross it's path?

2. Which side is the asteroid on..the side we are heading or the side we are leaving?

3. If this asteroid actually does cross Earth's path, has anyone plotted where that path crosses on the face of the planet? For example, if the path of the asteroid were a laser, where would that laser hit the surface as we passed by?


The overriding point is that the asteroid's orbit will be dramatically changed during its close passage of Earth as demonstrated in my overhead diagram: www.CurtRenz.com/asteroids . So its orbit cannot be permanently fixed in space, which renders it impossible to properly answer your question #1.

The asteroid will be passing from the south toward the north as it moves through its ascending node while slightly further from the Sun than the Earth. In other words, it will be passing the Earth on our night side while drifting from south to north as both objects maintain a similar pace as they orbit the Sun. The orbital change during passage will dramatically alter the asteroid's perihelion point as seen in my graphic. During this week the asteroid's heliocentric speed relative to the Earth will alternate among slightly faster, slower and faster as demonstrated by my same graphic. So any answer to your question #2 would involve ambiguities.

Your question #3 is addressed in my answer for #1.

#28 Darren Drake

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Posted 11 February 2013 - 04:11 PM

Whoops, Darren, I just realized you will not have the data in Solex for asteroid 2012 DA14. Aldo had e-mailed that to me.

For my location in Arlington Heights, Illinois on 2012 FEB 15, below are the asteroid's coordinates.

18:00 CST RA 13:10:35.2 Dec N 74° 13' 52"
19:00 CST RA 13:38:25.2 Dec N 78° 04' 24"
20:00 CST RA 14:10:01.9 Dec N 80° 44' 11"
21:00 CST RA 14:45:39.9 Dec N 82° 37' 17"
22:00 CST RA 15:25:02.5 Dec N 83° 57' 20"
23:00 CST RA 16:07:02.5 Dec N 84° 52' 58"


Since I am scheduled to work that night at the space center do you have the coordinates for later that night? 11:30 is about the soonest I can go for it...Thanks

#29 Centaur

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Posted 11 February 2013 - 04:22 PM

Since I am scheduled to work that night at the space center do you have the coordinates for later that night? 11:30 is about the soonest I can go for it...Thanks


After midnight the fast moving object will be dimmer than 13th magnitude. The forecast is for snow showers. Do you really want me to go through the rather involved effort again?

#30 cadfour

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Posted 11 February 2013 - 04:41 PM

Thanks Curt. Your diagram and explanation helped me visualize the path of the asteroid. I understand now, it's not as easy as saying...."where would it have hit?"

#31 Darren Drake

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Posted 11 February 2013 - 04:57 PM

No need if it's that involved. Thanks

#32 Centaur

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Posted 11 February 2013 - 05:04 PM

No need if it's that involved. Thanks


"Give a man a fish and you feed him for a day. Teach a man to fish and you feed him for a lifetime."
Chinese Proverb

If you'd really like to know, Darren, then follow the directions I gave for downloading and using Solex. Aldo's e-mail address is on the Solex website. Ask him to e-mail you the file for Asteroid 2012 DA14.

#33 Centaur

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Posted 11 February 2013 - 05:37 PM

Thanks Curt. Your diagram and explanation helped me visualize the path of the asteroid. I understand now, it's not as easy as saying...."where would it have hit?"


You’re welcome, Mike. Thanks for understanding. For Kepler, two-body calculations of celestial mechanics were easy. Add a third body, and it can become incredibly complex, almost chaotic. It gave Newton headaches.

For the major planets we have theoretical orbits for which we have formulae for making minor adjustments over time. For minor bodies, including Pluto, no long term theories have been devised for their orbits. We must rely on osculating orbital elements. Those are given for a particular epoch. The body’s position and velocity are then extrapolated relative to the Sun and nothing else. Those elements indicate how the body would move if the only two bodies in the universe were it and the Sun. In reality, the body quickly begins to deviate from the osculating orbit mainly due to the presence of planets. When a minor body gets really close to a major planet (such as asteroid 2012 DA14 this week) its osculating orbit and elements change quite dramatically. Of course those are always changing to some degree even when far from major planets. So this amplifies my mention of an asteroid’s orbit not being fixed in space.

#34 Unknownastron

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Posted 12 February 2013 - 12:22 AM

Here is a link to the article on the asteriod pass from Sky and Telescope website:

http://www.skyandtel...-to-Zip-Past...

The article has a very rough chart showing the general direction, but it also has a link to JPL and gives the instructions how to create an ephemeris for your specific latitude and longitude. I hand plotted it on a chart. Old school, but it works.
Clear skies and clean glass,
Mike

#35 Ruimteman

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Posted 12 February 2013 - 03:49 AM

How about trying the website I suggested earlier in this tread? All you have to do is input your location. It generates nice maps for you.

#36 *skyguy*

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Posted 12 February 2013 - 02:20 PM

How about trying the website I suggested earlier in this tread? All you have to do is input your location. It generates nice maps for you.


The "Visual SAT-Flare Tracker 3D" website is great! Thanks for the suggestion.

http://www.satflare.com/

#37 WillCarney

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Posted 13 February 2013 - 03:43 PM

I use Cartes du Ciel with current updates. It predicts the asteroid position rather well. Key is putting in your location and altitude. Even being 50 miles apart will change your sky position since this one's so close.

They are predicting partly cloudy which probably means total cloud cover for me. Just like today. Partly cloudy predicted but total cloud cover due to jets. William

#38 Tom Laskowski

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Posted 14 February 2013 - 08:15 AM

100% chance of snow here Friday night but it will be lake-effect snow and we might have some breaks in the clouds.

#39 drbyyz

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Posted 14 February 2013 - 10:37 AM

For those still looking for info on how to see this. Sky Safari pro/plus recently updated their predictions for it, so it should be pretty accurate to use. I may sit down later today and compare theirs with some other sites and see how they compare.

Other than that I'm looking forward to tracking this guy down tomorrow night. Will be mag 11+ and not moving terribly fast, but I'm sure I can wrangle it. I'd like to see motion through the eyepiece but it might be just on the verge of that, so a few field sketches should do it.

#40 Mark9473

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Posted 14 February 2013 - 03:10 PM

I use Cartes du Ciel with current updates. It predicts the asteroid position rather well.

Can you confirm that CdC takes into account the perturbations to the object's orbit by the Earth's gravity field at the moment of the fly-by?

If it's just a Keplerian calculation based on the current orbital parameters, it can't possibly be correct.

#41 WillCarney

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Posted 14 February 2013 - 04:21 PM

No idea how it's calculated. I don't have access to the source code. The FAQ and such does not mention it. It uses data elements from MPC for it's calculations. So I am hoping if CDC does not take in account the change MPC will update the data after close approach. Then I can download an updated file. Either way I use CDC to control the mount to find the asteroid. There was a bug reported specifically due to 2012DA14 and fixed but I can't read French to find out what the problem was. William

#42 Mark9473

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Posted 14 February 2013 - 05:15 PM

Well I ran CdC just now and the results are not even close to what the JPL site told me last week. Went and checked the bug report you mentioned and it's not all clear to me, but either way I'm not going to install beta version 3.7 now just for this one thing; I can manage with the JPL output.

#43 Ruimteman

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Posted 14 February 2013 - 09:13 PM

The asteroid is just about lunar distance now over Antarctica. Coming in at 6.3km/second. Should start snowing here soon, but might just clear enough by tonight.

#44 Darren Drake

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Posted 14 February 2013 - 10:33 PM

I ran the motion using skysafari pro. It spends the longest time near the Small Magellanic Cloud until about 6AM CST 2/15 and then really takes off. By noon its really moving like nothing else I've seen. By around 5 PM it pops up in the north and flies up to around the little dipper. To bad its gonna be cloudy here in Chicagoland.

#45 Nick Rose

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Posted 15 February 2013 - 01:00 AM

It will be clear hear in the Bay Area so I will try and get a picture of it.

Whats the best way to capture it? Just park the scope in a area where DA14 will pass and just continue to take pictures until you see movement? I'll be able to do 200sec. unguided.

#46 leviathan

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Posted 15 February 2013 - 02:02 AM

Today very bright bolid flew over Chelyabinsk in Russia:

http://www.youtube.c...d&v=7c-0iwBEswE

You can find a lot of videos on Youtube. Maybe that was some small part of 2012 DA14.

#47 core

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Posted 15 February 2013 - 02:26 AM

wow, even as coincidences go (2012 DA14 'herding' smaller bodies?), watching the various dash cam videos coming out now is a little disquieting.

#48 Ruimteman

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Posted 15 February 2013 - 03:46 AM

http://www.slate.com..._meteor_expl...
This is by Phil Plait with lots of videos.

#49 WillCarney

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Posted 15 February 2013 - 09:00 AM

The plots are all over the place. The Arlington position for 21:00 is 14 45 39, 82 37 17. NASA put's my Bloomington at 12 03 51, +42 32 and CDC puts it as 15 37 31, 84 11 51.

It's going to be cloudy at my location so it does not matter that much. But for future events it does. William

#50 Centaur

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Posted 15 February 2013 - 06:41 PM

If it's just a Keplerian calculation based on the current orbital parameters, it can't possibly be correct.


Indeed, Mark, you are correct. Normally osculating orbital elements are just fine as long as the epoch is fairly nearby. In the case of Asteroid 2012 DA14 these fail miserably today. They assume Kepler’s two-body orbits: Sun and asteroid. In this case, elements for the epoch at a certain hour are not good for the next hour. However, it is this method that most sources are using. It results in great inaccuracies today.

For the positions I gave as viewed from Arlington Heights, Illinois, I relied on the Solex astronomical numerical integration program. That program does give osculating elements for any chosen epoch, but the positions I posted did not invoke those elements. Instead I took the hourly positions directly from numerical integration which ignores the method of Kepler. It continuously takes perturbations into account by relying on Newton’s two more basic force equations of motion and gravitation.






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