 precision ephemeris of the sun - Printable Version +- HP Prime Forum (http://forum.hp-prime.de) +-- Forum: HP Prime (/forumdisplay.php?fid=1) +--- Forum: Software (/forumdisplay.php?fid=4) +--- Thread: precision ephemeris of the sun (/showthread.php?tid=95) precision ephemeris of the sun - cdeaglejr - 21-04-2016 04:33 PM This HP Prime program demonstrates how to call a subroutine named sun2 which computes a precision ephemeris of the sun. Here is the syntax for the routine EXPORT sun2(jdate) // precision ephemeris of the Sun // input // jdate = julian ephemeris date // output // rsun(1) = x-component of the eci position vector of the Sun (km) // rsun(2) = y-component of the eci position vector of the Sun (km) // rsun(3) = z-component of the eci position vector of the Sun (km) // rsun(4) = right ascension of the Sun (radians) // (0 <= rasc <= 2 pi) // rsun(5) = declination of the Sun (radians) // (-pi/2 <= decl <= pi/2) // // note // coordinates are inertial, geocentric, // equatorial and true-of-date // reference // Planetary Programs and Tables // by Pierre Bretagnon & Jean-Louis Simon and here is the screen display generated by the demo program. PRECISION EPHEMERIS OF THE SUN rsun_x = 128426556.337 km rsun_y = 71703229.3293 km rsun_z = 31080388.5969 km rmag = 150335371.833 km right ascension = 29.1755355809 deg declination = 11.9313969567 deg A PDF document included with the attached zip file has details of the algorithm.