one short question: “Is there a way to calculate and especially to display the greatest western and eastern elongation for Mercury?”



Hi Thomas,

There would have to be a way to do it in scripting, but it will involve a bit of geometry. I do see that the swiss ephemeris has it available but we have never exposed it and it would be a 3-6 month turn around for us to add it in. My whole astro engine overhaul has been delayed, but I can add this to that list.

Elongation angle is the angle between planet and sun as seen from earth. Greater Western would look like this



So we can take Geocentric PVAL for Sun and Mercury then take the difference between them. We will have to smooth the results to deal with one of them being over 360 degrees etc.

Here is a script to use

diff= Ps-Pm;

// deal with the spikes
smooth = if(diff > 180, diff-360, if(diff < -180, diff+360, diff));

smooth TurnsUp

This is the script for the arrows, but if we output “smooth” then you can see the plot at the bottom.

I’m not sure that this is the right number but it will give you a start and hopefully it gives you what you need right now.

All the best



Hi Mathew,

thank you really very much for your time and efforts to answer my question.

I think I can wait 3-6 months until you have overhauled your astro engine and have added the elongation feature to your astro engine.



Morning Mathew

May I check if elongation remains under consideration as an astro tool ?

Other than commenting here, I don’t know how else to express my interest in a tool already discussed like this on the forum ?



Hi Andrew,

My planned rewrite of the Astro engine has been delayed due to other projects taking priority. Instead, we have made a lot of fixes to tools like the Synodics and improved the speed of the interval tools.

Because this was logged with the rewrite I must confess that I have completely forgotten about it. I’ll add it to the schedule on its own. It will not be before Optuma 1.7 though.

Adding comments to posts is the best way, but please don’t add comments unless it is something that really would make a difference. We have finite resources and while I wish we could add everything, we have to pick and choose. Usually, it’s a balance of how hard is it? how many people want/need it? does it help us sell more Optuma?

All the best


Just expressing my interest on elongation too. Thanks for all you and the team at Optuma do.