[meteorite-list] Update: Asteroid 136849 approaching (over 1 km indiameter)
From: Bob Loeffler <bobl_at_meteoritecentral.com>
Date: Sun, 25 Jan 2009 11:21:35 -0700 Message-ID: <20090125182131.8B81110531_at_mailwash5.pair.com> Hi Doug, Thank you very much for the detailed info. I wasn't able to stay awake that night (I think it was around 12:30am when I finally went to bed), but I wouldn't have been able to see anything with my binoculars anyway since the magnitude was very low by that time. But now I know what kind of details I need to know for when it happens the next time. Thanks! Bob -----Original Message----- From: mexicodoug at aim.com [mailto:mexicodoug at aim.com] Sent: Sunday, January 18, 2009 5:00 PM To: bobl at peaktopeak.com; Meteorite-list at meteoritecentral.com Subject: Re: [meteorite-list] Update: Asteroid 136849 approaching (over 1 km indiameter) Hi Bob, sorry I didn't catch this sooner, and wish I could have helped more so you could see probable biggest ordinary chondrite of your life. I was skunked and I'm a bit unhappy at the moment for losing the sleep. I don't know where you live, but assuming it is close to lat. 39 Deg 56' 23"; long. W. 105? 8' 24", the asteroid will have dropped to the 14.5 magnitude and rise tonight at 01:25 AM MST. The 3/8's of a Moon will follow at 01:59 AM MST. So, you are probably out of luck, even if an accurate finders chart existed. Due to the closeness of the asteroid you really ought to specify where you are, and when you are observing (I bet you can easily get an error of several minutes from different positions on Earth). On top of that, there is uncertainty in the position even for a fixed single observer, as this is really pushing the orbital elements to an extreme (though after this pass, indubitably Arecibo and Goldstone observations and the resulting orbital refinements will make this more plausible in the near future). The best bet as this point is to beg, borrow or steal the combination for the Denver Astronomical Club's dark sky site East of your metropolis, where these observations now could be made with a good telescope with star drive and lots of luck or experience or both. If you have a planetarium program, you might try these orbital elements (they are not guaranteed , I'm very tired!): Epoch: 2454856.50000 (2009/1/25 0:00:00) o (argument of perihelion): 97.46551 O (longitude of ascending node): 110.94293 i (inclination): 7.78920 e (eccentricity): 0.5782656 a (semimajor axis): 1.4916402 AU M (mean anomaly): 336.59998 T (perihelion date): 2454234.35924 (2007/5/13 20:37:18) q (perihelion distance): 0.62908 AU H (mean visual magnitude): 17.62 G (magnitude slope factor): 0.15 In my first post I gave the link to orbital elements that would have allowed you to generate your personal star chart in any worthy planetarium program, I'm sorry you missed them. The second post then listed what Goldstone and Arecibo are using, I believe, or at least coordinates). By now something like that which is of questionable help for star-hopping but shows the asteroid being clobbered by Hercules' club (near Club star: Kornephoros) at exactly 3:00AM MST (Estimated Asteroid position: RA 16 32 44, Dec. +19 22 56, mag. 14.5) and then bonking the Hero of song and story's constellation directly in the head (Head star: Ras Algethi), 20 hours later: www.diogenite.com/136849SUP.jpg Note, while the distance has increased only about 15% from closest approach, due to the Sunlit portion (phase) the major fading is taking place. This can be visualized better by referring to the orbital diagram I gave a link to in the first post where the orbital elements are found. Best wishes and Great Skies, hope I didn't make a mistake as if anyone would really try this, considering Pluto will be twice as bright at the time mentioned than the asteroid that is the object of my recent crush... Doug -----Original Message----- From: Bob Loeffler <bobl at peaktopeak.com> To: Meteorite-list at meteoritecentral.com Sent: Sat, 17 Jan 2009 6:32 pm Subject: Re: [meteorite-list] Update: Asteroid 136849 approaching (over 1 km indiameter) Hi all, Does anyone have coordinates (or better yet, a star chart image) of where this asteroid is located? Thanks, Bob -----Original Message----- From: meteorite-list-bounces at meteoritecentral.com [mailto:meteorite-list-bounces at meteoritecentral.com] On Behalf Of mexicodoug at aim.com Sent: Friday, January 16, 2009 3:58 PM To: Meteorite-list at meteoritecentral.com Subject: [meteorite-list] Update: Asteroid 136849 approaching (over 1 km indiameter) Dear List, Drat's, I was completely rained out and will be again tonight, and then it head a little too "north" for me. Did anyone see this potential hammer asteroid inchworming from Ursa Major past Arcturus and towards Corona Borealis (actually it is thought to be a non-carbonaceous stony asteroid)? There is still plenty of time for the next two or three days to see it as it fades to Pluto brightness from its current status a being visible through big binoculars or amateur scopes. The actual closest approach is on January 17 at a couple minutes past 17:00 London time. T here is no chance this asteroid will hit Earth anytime soon, but is a good illustration of what is being done to track potentially Earth-threatening objects. Both the Puerto Rico's Arecibo ( http://www.naic.edu/public/the_telescope.htm ) and the Mojave Goldstone dishes ( http://www.jpl.nasa.gov/images/dsn/goldstone/ ) Gigantic Radio telescopes, on the NASA/NSF/UStaxpayer payroll, are dedicating serious time to it to figure out its shape, and whatever else they can glean, which while an academic question in this century, could help with strategies to deflect it if necessary at a time in the far future...Typically I think up to ten asteroids monthly (all PHA's, potentially hazardous) are within range and under RADAR study at these installations. It is also a Grrrrreat time to do some spectroscopy on the relatively intense light detectable from Earth during this pass. Basically, taking spectra of the reflected light and analyzing which colors/wavelengths are strongest to get a handle on the composition. Can't wait to find out what new is learned. Hopefully Arecibo stays afloat...:-) Here are the scheduling pages to see the crunching going on for over a week of observations (as we speak errr...breathe) to see what is being done about this object that will pass 11.31 LDs (Lunar Distances) from Earth: http://echo.jpl.nasa.gov/asteroids/1998CS1/1998CS1_planning.html Regarding the distance and its associated dangers - Here is an illustration of ONE Lunar Distance: http://tinyurl.com/ 9vyyty This is a rather big one and events concerning asteroids this size and proximity happen at best a a few times a year in a fun year. A couple of clarifying comments, the info on this web page indicates the Japanese were the ones who discovered it first, at this place, http://www.kumakogen.jp/culture/astro/astro_e.html Well the Japanese data is two days after the Chinese data so I don't know what's the problem with the crediting of the discovery. Second it mentions that the asteroid measures 0.9 km in diameter plus/minus a FACTOR OF TWO. That puts it between 0.5 and 1.8 km in diameter - so it is very likely to be over 1 km in diameter the catastrophic arbitrary threshold many talk about. Best wishes and Great Health, Doug -----Original Message- ---- From: mexicodoug at aim.com To: Meteorite-list at meteoritecentral.com Sent: Wed, 14 Jan 2009 5:10 pm Subject: Asteroid 136849 approaching (over 1 km in diameter) Dear Listees,? ? Thought I'd pass along to anyone interested in seeing a typical Hammer of God asteroid (no, it is not called Kali, but it really does have a devil of an orbital period: 666 days), in the form of Chinese discovered potentially threatening asteroid (136849) 1998 CS1 (That's CS1, not CSI :)). This asteroid is likely well over 1 kilometer in diameter and will be paying us a quite "close" visit on January 17 at about 5:00PM London time, when it will be about 4.35 m illion kilometers away (2.7 million miles) from Earth. That's about 11 Lunar Distances (11 times the distance from the Earth to the Moon).? ? For comparison, 4179 Toutatis, which made for a great deal of drama on 29 Sep 2004, is about twice the diameter of 136849 1998 CS1 and passed by Earth at 4 LD's. It was supposedly 10th magnitude, 5 times brighter, but was not as optimally placed to see for many of us.? ? Due to 136849's phase, it will actually be brightest tomorrow night (sometime between 10 PM and 12:30 AM) or whenever is just before Moonrise if you are in the northern hemisphere north of at least 15 degrees latitude or so. If you are South of that you need to put up with the fairly bright Moon but can try to look at it starti ng a couple of hours after Moonrise 'til dawn.? ? I think I'll give it a shot if conditions are ok, since it would be nice to see something this big, this close - about? the same level of difficulty as Toutatis was. For me timing critical as it will barely rise 15 degrees above the horizon when the Gibbous Moonriserises a little before midnight local time. But if you are a Hamburger (Germany) or Juneauean (Alaska), you can observe for at least two hours before Moonrise preferably in thermal knickers...? ? The predicted visual magnitude will be 12.25, well within the range of amateur telescopes. It will be moving against the starry background at about 40=2 0arcseconds per minute which is a third more that the diameter of Jupiter, for comparison, and a very comfortable speed for observation. It's roughly between the Big Dipper of Ursa Major (the Plough) and Leo.? ? For statical thoughts, anything coming within 11.31 LD's of Earth is ROUGHLY about one half-millionth a 'chance' to hit Earth by just looking at cross sectional area, and Earth occupies about one three hundred and twenty millionth of the volume of the sphere centered on Earth with a radius of 11.31 LD. And to think a LD (Lunar Distance) makes it seem so familiar and close! In 2080, it will pass by at 9.4 LD's if all goes according to plan...after a few close ones with Venus, too...? ? BTW today, the=2 0STARDUST spacecraft just passed Earth a couple of hours ago at 0.023 LD's, I think!? ? Here's the orbit of 136849:? http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=136849;orb=1? ? Here?re the discoverers:? http://ww? w.bao.ac.cn/bao/station/xl/index-e.html? ? Best wishes and Great Health,? Doug? ? ______________________________________________ http://www.meteoritecentral.com Meteorite-list mailing list Meteorite-list at meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list ______________________________________________ http://www.meteoritecentral.com Meteorite-list mailing list Meteorite-list at meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-listReceived on Sun 25 Jan 2009 01:21:35 PM PST |
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