Can you please explain how the interpolated Node is calculated?
We calculate the location on the eclipitic that the moon is at when it crosses the ecliptic, ie. 0 lattitude. at this time it will be exactly conjunct rahu or ketu using the true node calculation.
we then interpolate the moon's position between these two points.
With the true node calculation they have attempted to find exactly where the moon will cross the ecliptic while the moon is moving between ecliptic crossings. The problem with this is that they are projections and thus rahu and ketu go retro at times and really bounce around the ecliptic. With mean node calculation its simply based on a mean motion of the node, the moon is not used in the calculation at all. The result is that the moon will often cross the ecliptic and not be exactly conjuct rahu or ketu. Its obviously the least correct calculation we can use.
What I attempted was to create a mean motion between two true motions, the true motions being when the moon actually crosses the ecliptic. I got this idea when Deiter, who created the swiss ephemeris and who is by far the most accomplished astronomy programmer in the astrology world, told me that the true node is not really true. After I showed him my calculation, he said, you will have to test it, but do something like this would require some additional very complex calculations that I would have to think about... he has not had time to think about it, so I don't know what would need to be done to make it a better node option.
as it is, I dont think the interpolated node is 100% correct. I say this because I have some charts in my database with rahu right on the edge of a zodiac sign and the node option will decide if they have shamed planets or not. Their behavior and lives show shamed planets VERY clearly, but with the interpolated option rahu is not creating the shame as it moves into the next sign where it is alone. I worked extensively with this person, got to know every detail of their entire life over a 2 year period and its quite impossible for them to not hvae shamed planets. With true node, they have shamed planets. But,i also know, that in many cases true node is not showing the result accurately either in hair line examples like this. So we are still in need of a perfect node option. I will try to find that email from Deiter on this topic and if I find it email it to you and maybe this is something we can get worked out. Mean node is CERTAINLY, the most incorrect option and I have many cases that verify that.
Where the node option really concerns me is in Human Design astrology where a little change in the node position will cause the human design reader to give a big difference in respect to extremely important life living advice.