Solar Longitude to JD

[izubiaurre]

Hi,

I'm trying to figure out if it's a way to calculate the date and time (JD) in a year for a solar longitude. I mean, I want to make a function that makes the calculations something like that:

double SolarLongitudeToJD(int year, double solarLongitude)
{
	// Here goes the code

	return JD;
}

I have searched in Jean Meeus book but found nothing about it (maybe it's the first time I haven't found any solution for my calculations in the book). I think that in the 24th chapter, there are the reverse calculation for what I trying to find: for a given date, various solar coordinates calculations, with the solar longitude between them.
 

Thank you for advance.

[Stu Todd]

I'd like to help but "longitude" is relevant to Earth co-ordinates? The Julian Date is easily found, you mean the RA of the Sun for a given JD?

Suncalc.org is a great page, doesn't give JD but you can set the actual Z.

Hope that helps.

Stu

[izubiaurre]

If I'm understanding correctly what you've said, no. Solar Longitude is the position (angle, 0º-360º) in the elliptic orbit around the sun starting at the vernal equinox. Also, it differs in the number of days each range 0º-90º, 90º-180º, 180º-270º and 270º-360º. Wikipedia 

[Merlin66]

Or the Carrington solar rotation heliographic longtitude????

https://en.wikipedia.org/wiki/Solar_rotation#Carrington_rotation

[Stu Todd]

Ah I see what you're getting at. Does this link help with the maths?

http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?bibcode=2000JIMO...28..176O&db_key=AST&page_ind=0&data_type=GIF&type=SCREEN_VIEW&classic=YES

Stu

[izubiaurre]

On 07/03/2020 at 01:31, Stu Todd said:

Ah I see what you're getting at. Does this link help with the maths?

http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?bibcode=2000JIMO...28..176O&db_key=AST&page_ind=0&data_type=GIF&type=SCREEN_VIEW&classic=YES

Stu

Exactly. Thank you!