[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?
?
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Received on Sun 25 Jan 2009 01:21:35 PM PST


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