[Spice_discussion] precision of sun-earth radial velocity from
doerr at kis.uni-freiburg.de
Tue Apr 24 08:55:43 PDT 2012
is there a way how I could estimate the accuracy of velocities and
distances derived from SPICE?
I need very precise radial velocities (sub meter/second if possible)
between an earth based observatory and an arbitrary position on the sun
(neglecting solar rotation for the moment). I stumbled on SPICE and
thanks to the excellent documentation I soon was able to hack up a C
code that (most probably) does what I want.
The procedure I use is
* compute state 'O' of the observer wrt solar barycenter in J2000
frame (using spekzr)
* compute state of the target position on the solar surface 'T' wrt
* project velocity component of the observer-target state S = O + T
onto the Observer-Target line-of-sight unit vector to get the
I use the ITRF earth rotation kernel, in our case the difference is less
than 1 m/s in velocity.
I now wonder which absolute accuracy I can expect for such a calculation.
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