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From: TerryMoselaol.com
Date: Thu, 18 Mar 2004 14:58:09 EST
Subject: Closest Asteroid flyby!

Hi all, 

CLOSEST FLYBY EVER!

Less than 5 hours from the time this message is being issued, a tiny, newly
discovered asteroid will make the closest flyby past Earth that has ever been
predicted by astronomers.

The object, dubbed 2004 FH, (also known as NEO. 2003 FH )
is probably only about 20 meters in diameter (the size of a big house). An 
electronic circular issued late on March 17th by the Minor Planet Center  (MPC) 
in Cambridge, Massachusetts, indicates that it will definitely NOT hit the 
Earth. [If it did, the impact energy would be around 20 Megatons, or over 1,000 
times that of the Hiroshima bomb. TM] It will pass about 49,000 kilometers 
(30,500 miles) from Earth's center,
which is one-eighth the distance of the Moon. [That's only 26,500 miles from
the Earth's surface. TM]

This object was discovered on March 16th by astronomers of MIT's Lincoln
Near-Earth Asteroid Research (LINEAR) survey in Socorro, New Mexico. Further
observations made on the 17th at Klet Observatory (Czech Republic),
Starkenburg Observatory (Germany), and Modra Observatory (Slovenia) helped
the MPC compute its exact trajectory.

The flyby scenario for 2004 FH goes like this:
* At 18 hours Universal Time on March 18th, the asteroid will be 12th
magnitude as it glides just south of the star Spica in Virgo, heading west
* By 22 hours UT on the 18th, it will have brightened to 10th magnitude when
it passes closest to Earth in the constellation Antlia.
* At 0 hours UT on March 19th -- which is around the time darkness falls on
the East Coast of North America on Thursday, March 18th -- it will have
faded
back to 12th magnitude as it shoots by Sirius near the open star cluster
Messier 41. By then it will be receding from Earth and heading back into
space.

Because 2004 FH will be passing so close, it is not practical to include a
detailed ephemeris in this message. Its path across the sky depends greatly
on an observer's vantage point on Earth (owing to the parallax effect).
Observers who wish to locate it in small telescopes should use the MPC's
Ephemeris Service to make detailed predictions for their own geographic
location:

http://cfa-www.harvard.edu/iau/MPEph/MPEph.html

According to the orbit calculated by Gareth Williams, associate director of
the MPC, 2004 FH belongs to the Aten class of asteroids. It circles the Sun
in just under 9 months in very nearly the same plane as Earth's orbit. At
perihelion it swings well inside the orbit of Venus; at aphelion (as
currently) it ranges just outside that of the Earth.

[At time of writing I have not had time to do an epehemeris for Ireland: it
may just be visible from here at, or close to, its time of closest passage,
depending just how far South it goes in Antlia (which lies South of Hydra].
But remember that this object will be moving VERY fast - in only 6 hours it
moves from near Spica to near Sirius! Unless you have very accurate 'GoTo'
your best option is to find an easily recognisable starfield along its
track, point your telescope there with a widefield eyepiece, about 5 minutes
before it is due to pass through that area, and then look for a faint star
gliding across the field. Off the top of my head (no time to do
calculations!), at its closest it will be moving at about 15 arcminutes per
minute of time! That's roughly the diameter of the Moon in 2 minutes. Or
about the diameter of the disc of Saturn per second! So 'live' motion will
be discernable to the eye.

CCD experts can have a go, but you'll need a VERY wide field of view to be
sure of getting it - maybe a telephoto lens, or attach to big binoculars?

Good Luck.

Terry

PS  Dr Alan Fitzsimmons (QUB) has just provided this ephemeris for N Ireland 
- thanks Alan!

                       Equatorial coordinates                                 App. motion                             
    Date      Hour      RA            DEC       Mag    R     Delta   RA*cosDE DEC    
             (UTC)   h  m  s        d  '  "           (AU)    (AU)    "/min    "/min   
=========== ======  =============  ============ ===== ====== =======  ========  ========  
18 Mar 2004 19.000   13 12 19.359  -23 43 34.34  11.2 0.9962  0.0007 -415.8927 -272.8754  
18 Mar 2004 19.250   13  4 10.856  -24 55 20.25  11.1 0.9961  0.0006 -476.2974 -301.6714  
18 Mar 2004 19.500   12 54 43.776  -26 14 38.87  10.9 0.9961  0.0006 -549.0001 -333.1708  
18 Mar 2004 19.750   12 43 40.035  -27 42  6.37  10.8 0.9961  0.0006 -636.9032 -366.6718  
18 Mar 2004 20.000   12 30 36.600  -29 18  1.95  10.6 0.9960  0.0005 -743.4452 -400.5237  
18 Mar 2004 20.250   12 15  4.349  -31  2  8.77  10.5 0.9960  0.0005 -872.4087 -431.4300  
18 Mar 2004 20.500   11 56 27.262  -32 53  1.97  10.4 0.9960  0.0004-1027.2955 -453.4179  
18 Mar 2004 20.750   11 34  2.941  -34 47 19.09  10.3 0.9960  0.0004-1209.8388 -456.5689  
18 Mar 2004 21.000   11  7  6.596  -36 38 33.09  10.3 0.9959  0.0004-1417.0624 -426.1527  
18 Mar 2004 21.250   10 35  2.096  -38 16  5.68  10.2 0.9959  0.0004-1636.6405 -343.9601  
18 Mar 2004 21.500    9 57 43.414  -39 24 56.01  10.3 0.9959  0.0003-1842.1953 -194.8827  
18 Mar 2004 21.750    9 16  2.743  -39 47 59.29  10.4 0.9958  0.0003-1994.1495   19.9628  
18 Mar 2004 22.000    8 32  5.294  -39 11 51.29  10.5 0.9958  0.0003-2053.2145  271.2660  
18 Mar 2004 22.250    7 48 43.699  -37 33 38.47  10.7 0.9958  0.0003-2002.6823  507.3472  
18 Mar 2004 22.500    7  8 36.809  -35  3 27.99  11.0 0.9957  0.0003-1859.3983  680.9878  
18 Mar 2004 22.750    6 33 19.628  -32  0  0.57  11.3 0.9957  0.0004-1661.4703  773.1113  
18 Mar 2004 23.000    6  3 17.087  -28 42 56.46  11.7 0.9957  0.0004-1447.0272  793.0371  
18 Mar 2004 23.250    5 38  7.880  -25 27 35.48  12.1 0.9956  0.0004-1242.0323  763.3981  
18 Mar 2004 23.500    5 17 10.947  -22 23 27.57  12.4 0.9956  0.0004-1059.3734  706.5885  
18 Mar 2004 23.750    4 59 42.232  -19 35  9.26  12.8 0.9956  0.0004 -902.9072  638.9347  
19 Mar 2004  0.000    4 45  2.219  -17  4  1.84  13.2 0.9955  0.0005 -771.6572  570.3370  
19 Mar 2004  0.250    4 32 38.114  -14 49 36.14  13.5 0.9955  0.0005 -662.6252  505.9401  
19 Mar 2004  0.500    4 22  3.655  -12 50 30.04  13.8 0.9955  0.0006 -572.3134  447.9268  
19 Mar 2004  0.750    4 12 58.114  -11  5  2.29  14.1 0.9954  0.0006 -497.4196  396.8353  
19 Mar 2004  1.000    4  5  5.199  - 9 31 30.53  14.4 0.9954  0.0006 -435.0901  352.3818  
19 Mar 2004  1.250    3 58 12.070  - 8  8 19.70  14.6 0.9954  0.0007 -382.9632  313.9285  
19 Mar 2004  1.500    3 52  8.555  - 6 54  5.37  14.9 0.9953  0.0007 -339.1271  280.7300  
19 Mar 2004  1.750    3 46 46.538  - 5 47 34.25  15.1 0.9953  0.0007 -302.0496  252.0547  
19 Mar 2004  2.000    3 41 59.490  - 4 47 43.57  15.3 0.9953  0.0008 -270.5074  227.2374  
19 Mar 2004  2.250    3 37 42.117  - 3 53 39.93  15.5 0.9952  0.0008 -243.5235  205.6966  
19 Mar 2004  2.500    3 33 50.092  - 3  4 38.02  15.7 0.9952  0.0009 -220.3156  186.9351  
19 Mar 2004  2.750    3 30 19.849  - 2 19 59.37  15.9 0.9952  0.0009 -200.2541  170.5330  
19 Mar 2004  3.000    3 27  8.428  - 1 39 11.33  16.1 0.9951  0.0009 -182.8302  156.1376  
19 Mar 2004  3.250    3 24 13.356  - 1  1 46.06  16.2 0.9951  0.0010 -167.6302  143.4536  
19 Mar 2004  3.500    3 21 32.548  - 0 27 19.80  16.4 0.9951  0.0010 -154.3156  132.2338  
19 Mar 2004  3.750    3 19  4.243  + 0  4 27.81  16.5 0.9950  0.0011 -142.6080  122.2712  
19 Mar 2004  4.000    3 16 46.937  + 0 33 54.29  16.7 0.9950  0.0011 -132.2769  113.3918  
19 Mar 2004  4.250    3 14 39.344  + 1  1 14.76  16.8 0.9950  0.0012 -123.1304  105.4491  
19 Mar 2004  4.500    3 12 40.358  + 1 26 42.31  16.9 0.9949  0.0012 -115.0079   98.3194  
19 Mar 2004  4.750    3 10 49.020  + 1 50 28.35  17.0 0.9949  0.0012 -107.7740   91.8979  
19 Mar 2004  5.000    3  9  4.500  + 2 12 42.79  17.1 0.9949  0.0013 -101.3140   86.0952  
19 Mar 2004  5.250    3  7 26.074  + 2 33 34.35  17.3 0.9948  0.0013  -95.5306   80.8353  
19 Mar 2004  5.500    3  5 53.108  + 2 53 10.65  17.4 0.9948  0.0014  -90.3403   76.0528  
19 Mar 2004  5.750    3  4 25.046  + 3 11 38.43  17.5 0.9948  0.0014  -85.6714   71.6917  
19 Mar 2004  6.000    3  3  1.399  + 3 29  3.65  17.6 0.9947  0.0014  -81.4620   67.7035  
19 Mar 2004  6.250    3  1 41.737  + 3 45 31.56  17.7 0.9947  0.0015  -77.6583   64.0464  
19 Mar 2004  6.500    3  0 25.680  + 4  1  6.87  17.8 0.9947  0.0015  -74.2137   60.6839  
19 Mar 2004  6.750    2 59 12.888  + 4 15 53.74  17.8 0.9946  0.0016  -71.0872   57.5843  
19 Mar 2004  7.000    2 58  3.065  + 4 29 55.90  17.9 0.9946  0.0016  -68.2428   54.7200  
19 Mar 2004  7.250    2 56 55.946  + 4 43 16.71  18.0 0.9946  0.0016  -65.6489   52.0666  
19 Mar 2004  7.500    2 55 51.293  + 4 55 59.16  18.1 0.9945  0.0017  -63.2775   49.6029  
19 Mar 2004  7.750    2 54 48.900  + 5  8  5.96  18.2 0.9945  0.0017  -61.1038   47.3102  
19 Mar 2004  8.000    2 53 48.580  + 5 19 39.53  18.2 0.9945  0.0018  -59.1058   45.1717  
19 Mar 2004  8.250    2 52 50.168  + 5 30 42.10  18.3 0.9944  0.0018  -57.2636   43.1730  
19 Mar 2004  8.500    2 51 53.518  + 5 41 15.64  18.4 0.9944  0.0018  -55.5597   41.3009  
19 Mar 2004  8.750    2 50 58.500  + 5 51 21.97  18.5 0.9944  0.0019  -53.9784   39.5440  
19 Mar 2004  9.000    2 50  5.000  + 6  1  2.75  18.5 0.9943  0.0019  -52.5055   37.8919  
19 Mar 2004  9.250    2 49 12.916  + 6 10 19.47  18.6 0.9943  0.0020  -51.1282   36.3357  
19 Mar 2004  9.500    2 48 22.159  + 6 19 13.51  18.7 0.9943  0.0020  -49.8351   34.8670  
19 Mar 2004  9.750    2 47 32.651  + 6 27 46.12  18.7 0.9943  0.0020  -48.6159   33.4785  
19 Mar 2004 10.000    2 46 44.323  + 6 35 58.47  18.8 0.9942  0.0021  -47.4614   32.1639  
19 Mar 2004 10.250    2 45 57.114  + 6 43 51.62  18.9 0.9942  0.0021  -46.3631   30.9171  
19 Mar 2004 10.500    2 45 10.974  + 6 51 26.53  18.9 0.9942  0.0022  -45.3137   29.7331  
19 Mar 2004 10.750    2 44 25.857  + 6 58 44.12  19.0 0.9941  0.0022  -44.3062   28.6069  
19 Mar 2004 11.000    2 43 41.725  + 7  5 45.23  19.1 0.9941  0.0022  -43.3346   27.5346  

Last Revised: 2004 March 19th
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