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Sun coordinate positions

lparisi
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Sun coordinate positions

Sat Feb 23, 2019 12:52 pm
Hi,

I have the same question about the two Marble astrolib sun position functions.
I'm no able to understand the reference system of the position of the sun in both QuickSun() and Sun200::state()
I.e. in which reference frame (ECI TEME ECEF etc) the position of the sun is given.

Thanks in advance
lparisi
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Re: Sun coordinate positions

Thu Feb 28, 2019 8:16 am
Hi,

figure out that the sun functions return the position of the sun in elliptic coordinates.
In marble these coordinates are then converted in this way:

Ecliptic coordinates --> Equatorial coordinates --> Polar Coordinates --> Ra Dec
eclequ() carpol()

since the time argument of this function is in Julian centuries since J2000
i think that the after the conversion, to the equatorial, these coordinates are in ECI J2000

It is right?

 
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