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From: 	  TerryMoselat signaol.com
Subject:  Astronomy @ Castle Espie; ISS; Close asteroid
Date: 	23 March 2007 01:31:56 GMT
	
	
Hi all,
 
1. Another reminder about:
 IAA Public Observing Evening, WWT, CASTLE ESPIE: The Irish Astronomical Association will be hosting 
another in its very successful series of public observing evenings at Castle Espie on Saturday 24 March. 
We'll be observing a nice waxing Moon, Saturn, & other sky attractions, with indoor alternatives if cloudy. 
All welcome, and bring your own binoculars & portable telescopes if you have them.
 
2. ISS: The ISS is now making another series of passes visible from Ireland in the early morning hours: 
details as usual on the excellent, free, www.heavens-above.com
 
3. CLOSE ASTEROID FLYBY.
    There was an error in the text of my last email (not guilty, as I just copied & pasted!) in that 
a decimal point had been omitted in the estimated diameter of the asteroid! The true diameter is about 2.2km, 
not 22km! I reproduce most of the details here for convenience, with some further information:
 
Asteroid 2006 VV2 passes close to the Earth at the end of March and early April.  At its closest, on March 31, 
it will be 0.0226 AU away (8.8 lunar distances). This will be the closest known approach by an object this 
intrinsically bright until May 2036, when binary asteroid (66391) 1999 KW4 (H=16.4) approaches within 6 lunar
distances.  Observers should be able to see it through modest telescopes as it reaches 10th magnitude on March 
31st and April 1st.
 
It will move almost due South, from Ursa Major, through Leo Minor, into Leo. Its greatest apparent motion will 
be on 30/31 March, when it will be moving at more than 1 minute of arc per minute of time.
 
Since it will be so close, parallax effects will be considerable: thus you will need to plot its position 
against the star background for your own location to locate it accurately. The orbital elements below can be 
'plugged into' many computer programmes such as Skymap Pro, & it will then generate the track against star 
charts for your, or any chosen, location.
   If you can't do that, you can get the same results as follows. First obtain your latitude and longitude 
as accurately as possible. Then visit Link.
For a high accuracy ephemeris: Link 
Further details are on: Link
 
If you can't get those details, look for it at the time of the close appulses to the stars identified below 
(" v " = visual magnitude).

Between 01:00 and 03:00 UT on March 29 the asteroid passes within 25 arc min of galaxies M82 and M81 and between 
19:00 and 21:00 UT on March 31 it approaches within 3 degrees of galaxies M105, M96 and M95.  A list of close 
appulses is given below, along with the details of a possible occultation event visible from the UK on the evening 
of March 31.
    2006 VV2 will be a very strong radar target and observations are scheduled at Goldstone (March 27, 30, and 
April 1-3) and Arecibo (March 31 and April 1). VV2's physical properties are unknown, but its absolute magnitude 
of 16.7 suggests a diameter within a factor of two of about 2.2 km and there is roughly a 1- in- 6 chance that it 
is a binary system. Astrometric and photometric data are requested in support of the radar observations.

Orbital elements
Epoch 2007 Apr. 10.0 
Semimajor axis, a		2.3913823 AU
Eccentricity, e			0.6029924   
Inclination of orbit, i		23.63379 deg
Argument of perihelion		144.91495 deg
Long. ascending node		10.04975 deg
Mean anomaly, M			9.67407 deg
Period of orbit, P		3.70 years (1350.7 days)
Perihelion distance		0.949 AU 
Aphelion distance		3.833 AU
Absolute magnitude, H		16.7

Ephemeris
   Date        UT    RA (J2000) Decl.     Delta      r         El.   Ph.    V    "/min    P.A.

2007 03 25 0000  00 56 22  +82 13.6   0.065  0.989   80.8  95.5  14.2   7.76  037.1
2007 03 26 0000  02 24 30  +84 43,2   0.056  0.993   83.6  93.2  13.7  10.28  058.7
2007 03 27 0000  06 11 45  +85 13.2   0.047  0.997   87.5  89.8  13.2  14.41  115.0
2007 03 28 0000  08 53 39  +80 11.0   0.039  1.001   93.2  84.6  12.6  21.14  154.8
2007 03 29 0000  09 49 31  +70 20.8   0.031  1.005  101.9  76.3  11.9  32.23  168.1
2007 03 30 0000  10 14 23  +54 42.0   0.026  1.010  115.2  63.5  11.0  48.43  173.4
2007 03 31 0000  10 28 10  +32 31.9   0.023  1.014  132.6  46.4  10.3  61.58  175.6
2007 04 01 0000  10 36 54  +08 27.3   0.024  1.019  146.9  32.4  10.0  56.00  176.4
2007 04 02 0000  10 42 58  -10 35.2   0.028  1.024  149.6  29.6  10.3  39.11  176.5

Appulses
2007 Mar 28 20:04  27 UMa (V=5.1), Asteroid (V=12.0) 6' west of star
2007 Mar 29 01:20  Messier 82 (V=9.2), Asteroid (V=11.8) 25' east of galaxy
2007 Mar 29 02:20  Messier 81 (V=7.8), Asteroid (V=11.8) 15' east of galaxy
2007 Mar 30 19:51  Beta LMi (V=4.2), Asteroid (V=10.4) 15' west of star
2007 Mar 30 22:42  30 LMi (V=4.7), Asteroid (V=10.3) 22' east of star

OCCULTATION !!!
2007 Mar 31 20:38  HIP 51892 (V=7.25), Asteroid (V=10.0)
   This is a K2-type star and the track crosses the UK passing Ayr, Chester, Shrewsbury, Gloucester and 
Salisbury.  The exact position is uncertain so observers within say 50-100 km either side of the nominal 
position may witness a positive event.   The duration of any event is expected to be less than 0.2 sec 
but this can be recorded using a video camera given that the star is so bright.  The drop in brightness 
is expected to be close to 3 magnitudes.  (Roger Dymock, Director Asteroids and Remote Planets Section)
 
HIP 51892 also has the following alternative designations (the following information is from Skymap Pro 11):
 
Tycho catalog number:		 TYC 842-486-1
Hipparcos catalog number:	 HIP 51892
PPM catalog number:		 PPM 127542
SAO catalog number:		 SAO 99198
HD catalog number:		 HD 91785
BD number:			 BD +12 2235
WDS designation:		 BIG 1
 
Equatorial co-ordinates (epoch J2000.0, ICRS)
Right Ascension:	 10h 36m 06.7378s
Declination:		 +11° 36' 52.378"
 
This star is a DOUBLE STAR, with the following details (position for component 1):
RA (J2000.0):			 10h 36m 06.7s
Dec (J2000.0):			 +11° 36' 52"
Number of measurements:		 13
Date of first observation:	 1880
Position angle:			 339°
Separation:			 55.7"
Date of last observation:	 2002
Position angle:			 332°
Separation:			 59.3"
Magnitude of first component:	 7.40
Magnitude of second component:	 9.67
Spectrum:			 K2
Proper motion in RA:		 -0.013 "/year
Proper motion in dec:		 0.006 "/year
Secondary PM in RA:		 -0.085 "/year
Secondary PM in dec:		 0.013 "/year
DM number:			 +12 2235
 
IRELAND: Given the present uncertainty in the track, there is a slight chance that the extreme ENE coast of 
N Ireland could witness this occultation - the NE coasts of Co Antrim & Co Down lie within about 100 km of 
the track. If the asteroid is a binary, then the chances of an occultation visible from here are slightly greater.
    Any such observation would produce really valuable information, so anyone with suitable equipment 
should prepare to try to record it if at all possible.  I'll give an update if further information becomes 
available.
   (Even though the star is a double star, there is little chance that the G-type 9.7 mag secondary component 
could be occulted as seen from Ireland.)
 
Clear skies,
 
Terry Moseley

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Last Revised: 2007 March 23rd
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