[Spice_discussion] Aberration correction and body-rotational frame not simultaneously possible with de43x kernels

K.-Michael Aye kmichael.aye at gmail.com
Mon Oct 19 08:49:42 PDT 2015

Hello spicy people,

If I want to calculate positions with spice.spkpos (or similar), and want to use LT+S correction while calculating positions relative to a rotating IAU frame, like IAU_MARS, what kernels do I need? 
I am asking because with pck00010 and de430.bsp the following does not work: 
`spkpos(‘sun’, et, ‘IAU_MARS’,  ‘LT+S’, ‘mars barycenter’)`, 
while setting the reference frame to J2000, it works, or setting the correction method from ‘LT+S’ to ‘none’ it also works. 
It’s also interesting that with the older de421.bsp planetary spk kernel this still worked for Mars (but also not for the outer planets). 
Apparently, the mass center ephemeris that is still in de421 for Mars, but not anymore in the de430 contains the required reference data to do this. 
But how would I go about Pluto, for example, i.e. what kernels would I need there?

Any hint would be welcome!


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