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JuliaSpaceMissionDesign / Ephemerides.jl

A Modern Binary Ephemeris Reader for Julia, in Julia.
https://juliaspacemissiondesign.github.io/Ephemerides.jl/
MIT License
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Time handling as two floating 64-bits variables #14

Closed MicheleCeresoli closed 11 months ago

MicheleCeresoli commented 1 year ago

Evaluate whether implementing time as two floating-point 64-bits variables is worth and quantify the accuracy gain.

MicheleCeresoli commented 11 months ago

This issue was originally opened because of an email exchange with the CALCEPH developers that stated that certain SPK types (e.g., type 20) were more sensible than others to the way time is managed in the library. However, some preliminary tests have shown that the differences with SPICE were due to a missing term in the Chebyshev integral.

Handling time expressed as seconds since J2000 with a single floating-point 64-bits variable does not seem to introduce great inaccuracies, with the minimum time resolution being about 3 microseconds. This issue is temporarily closed and time management is left as is.