Astronomical coordinates

Please give the formulae for converting from celestial coordinates to
heliocentric.
Thanks.

See the web site by Paul Schlyter http://stjarnhimlen.se/english.html

"Jake" wrote in message
...
Please give the formulae for converting from celestial coordinates to
heliocentric.
Thanks.

Jake wrote:
Please give the formulae for converting from celestial coordinates to
heliocentric.

condescending_disclaimer If this is homework, you are hurting yourself
as well as anyone else in the class. /condescending_disclaimer

You can't. Heliocentric coordinates are three-dimensional. Celestial
coordinates are two-dimensional. You can therefore go from heliocentric
to celestial (provided you know the Earth's heliocentric coordinates,
too), but you can't go from celestial alone back to heliocentric. If
you also know the distance to the object, *and* you know the Earth's
heliocentric coordinates, then you can convert to heliocentric.

In this case, it's pretty trivial. Find the geocentric coordinates as

xg = r*cos(dec)*cos(ra)
yg = r*cos(dec)*sin(ra)
zg = r*sin(dec)

then add the heliocentric coordinates of the Earth to get the those of
the object.

--
Brian Tung
The Astronomy Corner at http://astro.isi.edu/
Unofficial C5+ Home Page at http://astro.isi.edu/c5plus/
The PleiadAtlas Home Page at http://astro.isi.edu/pleiadatlas/
My Own Personal FAQ (SAA) at http://astro.isi.edu/reference/faq.html

Dennis Allen wrote:

See the web site by Paul Schlyter http://stjarnhimlen.se/english.html

Thanks again. :-)