How to make the estimated cd value as accurate as possible during the GPS data OD. The more GPS data, the more accurate the cd value obtained, is this right?
This cd value I want to use for orbit propagation.
Thanks!
Hi @newWL
Your question is problably one of the most difficult one of space mechanics 
This question has be treated in hundreds of papers during the last decades.
To simplify, having accurate Cd value is a combination of multiple factors. Three important ones are:
- The more data, the better accuracy
- Good knowledge of the atmosphere
- Good knowledge of your spacecraft geometry
The most difficult one is probably the second point because it is also a combination of (1) good knowledge of space weather data and (2) a good atmosphere model to compute the density.
You can have a lot of accurate GPS data, if you have a bad knowledge of the atmosphere your Cd estimation will be wrong.
Best regards,
Bryan
Thank you for your prompt reply. That’s the answer I want to know.