Hi, hopefully a simple question. I have not been able to find an answer in the API or technical docs.
Are the IERS2010 (e.g. Section 6.1) secular terms automatically applied to the gravity coefficients or is this something I have to explicitly specify in the .gfc file, or elsewhere. Specifically I am using EGM2008.
Thanks in advance.
-Mike
The terms used have to be included in the .gfc file.
The terms present in IERS conventions 2010 are specific to EGM2008, and Orekit can load many other models which have very different (and much more complete) time-dependency models. As an example, the gravity field we propose in the example orekit-data is Eigen 6S and has trends and harmonic coefficients for all spherical harmonic terms up to degree and order 50, whereas IERS conventions propose just a few linear terms for EGM2008.
So Orekit just loads the file and applies what it finds in the file. If there are time-dependent terms, it will apply them. If there are no time-dependent terms, it will apply a static gravity field.
Hi Luc,
Thank you for your response. I do understand all the fine distinctions between the temporal dependence treatments in various gravity models. The application here is an apples-to-apples comparison between propagators. I’ll create a custom gfc file for EGM2008 with the IERS2010 secular variations.
Thanks again for help.
-Mike