author : david vallado 719-573-2600 28 jun 2005
author : david vallado 719-573-2600 28 jun 2005
inputs :
opsmode - mode of operation afspc or improved 'a', 'i'
satn - satellite number
drag - sgp4 type drag coefficient kg/m2er
ecco - eccentricity
epoch - epoch time in days from jan 0, 1950. 0 hr
argpo - argument of perigee (output if ds)
inclo - inclination
mo - mean anomaly (output if ds)
no - mean motion
nodeo - right ascension of ascending node
outputs :
rec - common values for subsequent calls
return code - non-zero on error.
1 - mean elements, ecc >= 1.0 or ecc < -0.001 or a < 0.95 er
2 - mean motion less than 0.0
3 - pert elements, ecc < 0.0 or ecc > 1.0
4 - semi-latus rectum < 0.0
5 - epoch elements are sub-orbital
6 - satellite has decayed
procedure sgp4init
this procedure initializes variables for sgp4.
author : david vallado 719-573-2600 28 jun 2005 author : david vallado 719-573-2600 28 jun 2005
inputs : opsmode - mode of operation afspc or improved 'a', 'i' satn - satellite number drag - sgp4 type drag coefficient kg/m2er ecco - eccentricity epoch - epoch time in days from jan 0, 1950. 0 hr argpo - argument of perigee (output if ds) inclo - inclination mo - mean anomaly (output if ds) no - mean motion nodeo - right ascension of ascending node
outputs : rec - common values for subsequent calls return code - non-zero on error. 1 - mean elements, ecc >= 1.0 or ecc < -0.001 or a < 0.95 er 2 - mean motion less than 0.0 3 - pert elements, ecc < 0.0 or ecc > 1.0 4 - semi-latus rectum < 0.0 5 - epoch elements are sub-orbital 6 - satellite has decayed
locals : cnodm , snodm , cosim , sinim , cosomm , sinomm cc1sq , cc2 , cc3 coef , coef1 cosio4 - day - dndt - em - eccentricity emsq - eccentricity squared eeta - etasq - gam - argpm - argument of perigee nodem - inclm - inclination mm - mean anomaly nm - mean motion perige - perigee pinvsq - psisq - qzms24 - rtemsq - s1, s2, s3, s4, s5, s6, s7 - sfour - ss1, ss2, ss3, ss4, ss5, ss6, ss7 - sz1, sz2, sz3 sz11, sz12, sz13, sz21, sz22, sz23, sz31, sz32, sz33 - tc - temp - temp1, temp2, temp3 - tsi - xpidot - xhdot1 - z1, z2, z3 - z11, z12, z13, z21, z22, z23, z31, z32, z33 -
coupling : getgravconst- initl - dscom - dpper - dsinit - sgp4 -
references : hoots, roehrich, norad spacetrack report #3 1980 hoots, norad spacetrack report #6 1986 hoots, schumacher and glover 2004 vallado, crawford, hujsak, kelso 2006