3.3 Cometary Orbits for Celestia

3.3.1: Comet Hale-Bopp.
3.3.2: Comet Hyakutake.
3.3.3: Comet Shoemaker-Levy 9.
3.3.4: Comet 81P/Wild 2.
3.3.5: Comet 46P/Wirtanen.
3.3.6: Comet C/2000 V1 (NEAT).
3.3.7: misc.

• http://cfa-www.harvard.edu/icq/icq.html the Internationlal Comet Quarterly's Comet Information Website.
• How to transform orbital elements into Celestia's SSC format
• Selden's List of Celestia Resources

The .SSC files below have Unix-style bare line-feeds as the record delimiters. The Windows versions of Celestia, Emacs and Wordpad read and display the files just fine, but they aren't so readable if you use Notepad. Sorry.

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3.3.1: Comet C/1995 O1 Hale-Bopp

Object	Orbit Files	Web Sites	Comments
Comet C/1995 O1 Hale-Bopp	.	Hale-Bopp JPL Home page First International Conference on Comet Hale-Bopp, Feb 2, 1998, Puerto de la Cruz, Tenerife, Spain.	Information that I've included in both files was found in abstracts of presentations at the conference. Radius: approximately 20km H.A.Weaver, Johns Hopkins Univ. RotationPeriod: approximately 11.34 hours M.Kidger et.al., Teide Obs., Tenerife
"The Great Comet of 1997"	hale-bopp.ssc (1KB, 26Oct2002)	http://cfa-www.harvard.edu/iau/Ephemerides/Comets/1995O1.html	Orbital elements obtained from the IAU's Minor Planet Center
.	hale-bopp-horizons.ssc (1KB, 26Oct2002)	http://ssd.jpl.nasa.gov/horizons.html	Orbital elements obtained from JPL's Horizons Ephemeris System using its telnet interface.

Two different sets of orbital elements are provided above because the Horizons ephemeris results in a position that is about 54,400 kilometers closer to us than CfA's values. While Horizons provides much more precise values, I don't know which of them is more accurate. At a distance of almost 17AU, however, the difference doesn't seem to be very large.

3.3.2: Comet C/1996 B2 Hyakutake.

Object	Orbit Files	Web Sites	Comments
Comet C/1996 B2 Hyakutake	.	Comet Hyakutake JPL homepage http://www.lowell.edu/Research/Projects/hyakutake_research/hyaresearch.html	Radius: 1.3km RotationPeriod: 6.23 hours
"The Great Comet of 1996"	hyakutake.ssc	http://www.psrd.hawaii.edu/Feb97/Bright.html	Low precision set of orbital parameters from the University of Hawaii's Web page,
.	hyakutake-yeomans.ssc (1.5KB, 30Oct2002)	http://www.jpl.nasa.gov/comet/hyakutake/ephemjpl8.html	Three higher precision sets of values as determined by Don Yeomans of JPL in 1996: for 25-March-1996 (~closest approach to Earth), for 16-June-1996 and for 06-July-1996.
.	hyakutake-horizons.ssc (1.5KB, 30Oct2002)	http://ssd.jpl.nasa.gov/horizons.html	Two sets of Horizons' orbital parameters for 28-October-2002 and for 26-March-1996, (~closest approach to Earth).
.	hyakutake-h-1dec96.ssc (1KB, 10jul03)	http://ssd.jpl.nasa.gov/horizons.html	Horizons' orbital parameters for 1-December-1996 They're no longer providing ephemeris data past 30-Dec-1996.

Some significant incidents:
• The closest approach to Earth was predicted at an early stage to be on 25-Mar-1996 at a distance of about 0.1 AU. Celestia's display of both Horizon's and Yeoman's orbital parameters agree: 0.101 to 0.102 AU. Note, however, that I had to substitute significantly larger "calculated" values for the periods instead of those mentioned by Yeoman.
• Perihelion: 1-May-1996
• The comet's tail was encountered by the Ulysses probe (http://ulysses.jpl.nasa.gov) on May 1, 1996 (Nature, Apr 6, 2000) The Ulysses' orbital elements are included spacecraft.html. See also: http://www.jpl.nasa.gov/comet/hyakutake/news52.html.
• The comet was imaged near perihelion by the SOHO probe on April 29 - May 6, 1996. See http://lasco-www.nrl.navy.mil/b2-1996.html. SOHO is stationed at the Earth's L1 Lagrange point. Keplerian orbital elements are not applicable, so I haven't included an .SSC file.
• Comet Hyakutake now is almost 20AU from Earth, far to the south of the ecliptic.

Initially I thought that the Horizons values must have serious problems, since their periods are larger than Yeoman's predictions by a factor of 10 or more. They seem to predict the distance of the closest approach to the Earth just as accurately, however.

3.3.3: Comet 1993e Shoemaker-Levy 9.

Object	Orbit Files	Web Sites	Comments
Comet 1993e Shoemaker-Levy 9	.	Shoemaker-Levy 9's JPL home page	Fragments of comet 1993e collided with Jupiter starting at 20:11:00 16 July 1994 UT
.	sl9_2.ssc (5KB, 28Sep2002)	IAU Circular 5800 by Brian G. Marsden, May 22, 1993 "Osculating Heliocentric Orbital Elements for Shoemaker-Levy 9 Fragments," by D.K. Yeomans and P.W. Chodas / JPL 22 February, 1994 11 July, 1994.	This file contains several successive sets of heliocentric orbital elements for Fragment A of comet Shoemaker-Levy 9 (1993e) showing progressively better approximations for gravitational effects.
SL9-B following SL9-A to Jupiter	sl9.zip (4.5KB, 28Sep2002, updated 15Feb2003)	Keplerian orbital elements obtained directly from P.W. Chodas describing the final trajectory of the comet fragments.	This Zip archive contains two .SSC files: sl9_solar.ssc -- Heliocentric orbital elements for SL9 fragments, all set to be class "comet" sl9_jovian.ssc -- Jovicentric orbital elements for SL9 fragments. Fragment A is set to be class "comet", the remainder are class "asteroid" The Jovian ssc was updated to include more accurate sizes of the fragments and to have "Ending" times corresponding to the impact times. See http://www.lpi.usra.edu/meetings/lpsc97/pdf/1351.PDF and http://nssdc.gsfc.nasa.gov/planetary/impact.html.
.	sl9-1-xyz.ssc (0.5K 6Nov2002) sl9-1-horiz.xyz (46KB 6Nov2002)	(Put the .ssc file into the /extras/ directory and the .xyz file into the /data/ directory.)	Horizons xyz trajectory just for fragment A: 300 samples 00:00 18-June through 23:00 18-July, to provide an overview of the trajectory plus 240 samples 00:00 15-July through 23:00 16-July for precise tracking of the collision.

3.3.4: Comet 81P/Wild 2.

Object	Orbit Files	Comments
Comet 81P/Wild 2	Wild 2 JPL home page.	See spacecraft.html for information on the Stardust cometary probe's orbit, which will be visiting Wild 2 in 2004.
.	wild-2.ssc (1.5KB, 25Jun2004)	This file contains orbital elements obtained from three sources: http://stardust.jpl.nasa.gov/comets/wildephem.html for the 1997 perihelion passage (labelled just "Comet 81P/Wild 2") from http://www.imcce.fr/ephem/comets/HTML/english/CIA0008.html for the comet's predicted 2003 perihelion passage (labelled "Comet 81P/Wild 2 2003") from JPL's Horizons Ephemeris System at http://ssd.jpl.nasa.gov/horizons.html, using its telnet interface for the day of the Stardust encounter (labelled "Comet 81P/Wild 2 Horizons"). and on 25-June-2004 from JPL's Near Earth Object service at http://neo.jpl.nasa.gov/cgi-bin/db?name=81P As seen in Celestia, the IMCCE's orbit places the comet and the Stardust probe closest: only about 400km apart.

3.3.5: Comet 46P/Wirtanen.

Object	Orbit Files	Comments
Comet 46P/Wirtanen	Comet Wirtanen's AMS home page.	Originally the primary destination of ESA's Rosetta mission. See spacecraft.html. (Rosetta has been postponed for at least a year.)
.	wirtanen.ssc	Minor Planet Circular MPEC 2002-M33 by Brian G. Marsden.

3.3.6: Comet C/2002 V1 (NEAT).

Object	Orbit Files	Comments
Comet C/2002 V1 (NEAT)	Discovered by the Near Earth Asteroid Tracking program.	Sun grazing (0.1 AU perihelion distance)
.	c2002_v1.ssc	Minor Planet Circular MPEC 2002-V31 by Brian G. Marsden.

Note: (NEAT) means that it was discovered by NEAT, not that NEAT is an alternative name for the comet. I find it rather annoying that science journalists who should know better were confused by this common astronomical notation.

3.3.7: misc.

• histogram of cometary apohelia
  http://www.sdss.org/news/features/19990813.comet.img3.html
• Kuiper Belt and Oort Cloud
  http://seds.lpl.arizona.edu/nineplanets/nineplanets/kboc.html

• Interstellar probe mission
  http://interstellar.jpl.nasa.gov/
  • An Interstellar Probe Mission to the Boundaries of the Heliosphere and Nearby Interstellar Space
    http://interstellar.jpl.nasa.gov/interstellar/ISP_Space2K_v4.pdf
    Mewaldt, R.A. and Liewer, P.C.

    (diagram of nearby space)

• annual meteor showers

  Name	Comet	Date	Radiant	ZHR at max	Ref
  Quadrantids	?	3Jan	Bootes	60
  Lyrids	Thatcher	22Apr	Lyra	10
  Eta Aquarids	Halley	4May	Aquarius	35
  Delta Aquarids	?	28Jul	Aquarius	20
  Perseids	Swift-Tuttle	12Aug	Perseus	75
  Orionids	Halley	21Oct	Orion: RA 95, Dec +16	N:~20, S: ~40	http://comets.amsmeteors.org/meteors/showers/orionidobs.html
  Taurids	Encke	4-7Nov	Taurus: RA 54, Dec +21	7	http://comets.amsmeteors.org/meteors/showers/taurids.html
  Leonids	Temple-Tuttle	17Nov	Leo: RA 112.5 Dec 32.6	10
  Geminids	Phaethon (Asteroid)	14Dec	Gemini	75
  Ursids	Tuttle	22Dec	Ursa Minor	5

3.3.1: Comet Hale-Bopp.
3.3.2: Comet Hyakutake.
3.3.3: Comet Shoemaker-Levy 9.
3.3.4: Comet 81P/Wild 2.
3.3.5: Comet 46P/Wirtanen.
3.3.6: Comet C/2000 V1 (NEAT).
3.3.7: misc.

• How to transform orbital elements into Celestia's SSC format
• Selden's List of Resources for Celestia

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This Web page is maintained by Selden Ball at Wilson Lab.
Please send any comments or corrections to seb@lepp.cornell.edu