"The asteroid, referred to as 2012 DA14, has a diameter of approximately 45m and an estimated mass of 130,000 tonnes.
It was discovered at the start of 2012 and is set to travel between the Earth and our geostationary communication satellites on 15 February 2013.
At a distance of just 22,500km this will be the closest asteroid ‘fly by’ in recorded history." http://www.cosmosmagazine.com/news/6...ory-pass-earth
On this date, the asteroid will travel rapidly from the southern evening sky into the northern morning sky with its closest Earth approach occurring about 19:26 UTC when it will achieve a magnitude of less than seven.. http://neo.jpl.nasa.gov/news/news174.html
For Casino NSW the position and mag at one hour intervals are:
Date (UT) RA dec mag
2013-Feb-15 17:00 (4am DST) RA 10 25 52.64 dec -76 18 59.7 mag 10.67 in Cha
2013-Feb-15 18:00 (5am DST) RA 10 54 01.76 dec -59 12 07.1 mag 9.27 (near eta Car start of astro twilight Feb 16)
2013-Feb-15 19:00 (6am DST) RA 11 09 06.30 dec -22 15 33.6 mag 7.56 in Crt
What are the odds it takes out a satellite or two?
... and if it does, will that be enough to perturb it's trajectory and make things more interesting? Probably nothing more than like swatting flies - it won't feel a thing!
On the 15th at 23:00 AEST, 13:00 UT it will be only 4.5 degs from Sigma Octans, and the moon sets at 21:28 Brisbane time, so no moon to make things difficult
If you can spot it,you should be able to track it for the rest of the night, as it is moving fast against the background stars.
Cheers
Times are UTC. Sydney is UTC + 11 hours.
So, for example, 2013-Feb-15 12:00 UTC corresponds to 2013-Feb-15 23:00 AEDT,
that is 11pm in Sydney on the night of the 15th of Feb.
R.A._(ICRF/J2000.0)_DEC =
J2000.0 astrometric right ascension and declination of target center.
Azi_(a-appr)_Elev =
Airless apparent azimuth and elevation of target center. Corrected for
light-time, the gravitational deflection of light, stellar aberration,
precession and nutation. Azimuth measured North(0) -> East(90) -> South(180) ->
West(270) -> North (360). Elevation is with respect to plane perpendicular
to local zenith direction. TOPOCENTRIC ONLY. Units: DEGREES
APmag =
Asteroid's approximate apparent visual magnitude by following definition:
APmag = H + 5*log10(delta) + 5*log10(r) - 2.5*log10((1-G)*phi1 + G*phi2).
In principle, accurate to ~ +/- 0.1 magnitude. For solar phase angles > 90 deg,
the error could exceed 1 magnitude. No values are output for phase angles
greater than 120 degrees, since the extrapolation error could be large and
unknown. Units: NONE
Illu% =
Fraction of target circular disk illuminated by Sun (phase), as seen by
observer. Units: PERCENT
Cnst =
Constellation ID; the 3-letter abbreviation for the name of the
constellation containing the target center's astrometric position,
as defined by IAU (1930) boundary delineation.
It is important for observers to note that since this object is passing so close to
Earth, the effects of parallax become significant, so you should compute an
ephemeris based on your observing city or town. http://ssd.jpl.nasa.gov/horizons.cgi#top
For example, at 17:00 UTC, there is a 22 arc minute (over one third of a degree)
difference in apparent RA/Dec from Glen's location in Casino, NSW compared to
an observer in Sydney, even though the distance between Casino and Sydney is
only 588km.
Yup, this will be a great on to watch and is travelling at 2283.35" per min (if my calculations are close to correct, that's about 2/3rd of a degree every 60 seconds.
From a dark sky site it will be possible to watch this with binos! Incredible.
I've recorded a few of these objects but none near as this. As has been said already, parallax is critical so plot out the path locally, find out when it passes an obvious star, then wait in ambush for it to enter the field of view...
Ron, which parameters did you feed Horizons? If I use:
Code:
Current Settings
Ephemeris Type [change] : ELEMENTS
Target Body [change] : Asteroid (2012 DA14)
Center [change] : Sun (body center) [500@10]
Time Span [change] : discrete time(s)=2013-02-15 18:00
Table Settings [change] : defaults
Display/Output [change] : plain text
I get something like what you pasted. The easiest part to use is the bit below. The "Symbol meaning" bit identifies what value goes in each box. You can paste them as they appear here and TheSky can handle the scientific notation. The only tricks are:
TheSky6 calls "Argument of Perifocus" in the Minor Planets "Add" panel "Argument of Perihelion".
The day in "Element epoch" is the day as decoded from MJD with the decimal part added - so in this case 15.25.
and I don't seem to be able to stop the editor wrapping this block without butchering it. It sort of looks like this:
Code:
$$SOE
2456339.250000000 = A.D. 2013-Feb-15 18:00:00.0000 (CT)
EC= 1.119223267411774E-01 QR= 8.793252519475666E-01 IN= 1.277276690753689E+01
OM= 1.471236673414090E+02 W = 2.645957382478340E+02 Tp= 2456256.793500953820
N = 1.000359691344981E+00 MA= 8.248615793535961E+01 TA= 9.532953427349806E+01
A = 9.901445317512164E-01 AD= 1.100963811554866E+00 PR= 3.598705576750907E+02
$$EOE
Coordinate system description: Ecliptic and Mean Equinox of Reference Epoch Reference epoch: J2000.0
xy-plane: plane of the Earth's orbit at the reference epoch
x-axis : out along ascending node of instantaneous plane of the Earth's
orbit and the Earth's mean equator at the reference epoch
z-axis : perpendicular to the xy-plane in the directional (+ or -) sense
of Earth's north pole at the reference epoch.
Symbol meaning [1 AU=149597870.691 km, 1 day=86400.0 s]:
JDCT Epoch Julian Date, Coordinate Time
EC Eccentricity, e
QR Periapsis distance, q (AU)
IN Inclination w.r.t xy-plane, i (degrees)
OM Longitude of Ascending Node, OMEGA, (degrees)
W Argument of Perifocus, w (degrees)
Tp Time of periapsis (Julian day number)
N Mean motion, n (degrees/day)
MA Mean anomaly, M (degrees)
TA True anomaly, nu (degrees)
A Semi-major axis, a (AU)
AD Apoapsis distance (AU)
PR Sidereal orbit period (day)
Follow this link, change your location and select a timespan for the observation - you will get a very accurate set of coordinates to plot manually (or just follow in may case)
Thanks Gary, I had that, but the sky would not except it, so I tried importing it from the web,and it excepted it.
Cheers
PS I hope today is not hot for you
too confusing for me....I'll try the coordinate thing and even though I can't really find the SCP, I can get pretty close.......
I'm on the sapphire coast near Merimbula.....2548.......
Andrew
Follow this link, change your location and select a timespan for the observation - you will get a very accurate set of coordinates to plot manually (or just follow in may case)
All the user info is stored in cookies, so your link won't help others. Set it to something like:
Code:
Current Settings
Ephemeris Type [change] : OBSERVER
Target Body [change] : Asteroid (2012 DA14)
Observer Location [change] : user defined ( your location goes here )
Time Span [change] : Start=2013-02-15 18:00, Stop=2013-02-15 21:00, Step=5 m
Table Settings [change] : QUANTITIES=1,4,9,20,23,24,29,34
Display/Output [change] : plain text
and don't forget to put 399 in the bottom box to signify it is on earth.
What about Melbourne? I don't fully understand all these numbers the generator is pumping out.
Does anyone know a good website that has detailed descriptions of what each column means and how to use it. I would like to learn how to read these complex tables.
.
