Talk:Ecliptic coordinate system

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[edit] Celestial latitude and longitude

I thought this was the place to explain a series of related changes I've made. I restored the Ecliptic latitude and Ecliptic longitude articles, because the orphan Celestial latitude and Celestial longitude articles had become redirects to Declination and Right ascension, which are quite wrong. They needed something to point to and they now redirect to the restored Ecliptic latitude and Ecliptic longitude articles. SteveMcCluskey 05:22, 20 February 2007 (UTC)

[edit] conversion algorithm

I've been trying to implement functions based on the text provided in this section and I must confess to being totally confused. If we consider the first cas eof converting from ecliptic (RA,Dec) to equatorial (lat,lon) then to state the obvious we know (RA,Dec) but we do not know (lat,lon), but the article reads as if we know all 4 variables. For instance, the first line of the algorithm states "Calculate the terms right of the = sign of the 3 equations given above", but how is it possible to do this if we don't yet know (lat,lon)?

If you know (RA,Dec), you compute the right sides of the second set of equations. If you know (lat,lon), you compute the right sides of the first set of equations. —Tamfang (talk) 07:39, 4 April 2008 (UTC)

The second line of the algorithm states "taking the cos α cos δ as the X value". Are we to interpret this x=cos α cos δ or x=cos λ cos β because if it's the 2nd version, again we don't know lambda and beta.

I would suggest interpreting "α" as α and "δ" as δ, but that's just me, you may find some other approach more useful. —Tamfang (talk) 07:39, 4 April 2008 (UTC)

The closing line of the algorithm section states "Similarly for the equatorial to ecliptic transformation". After coding what I thought was the algorithm was, doing the inverse calculation I don't get back the original (RA,Dec) values from the (lat,lon) computer values. What's really needed for this page is an example. gmseed 28/03/2008