I use TLE sets supplied on this website to find the future position of satellites (well usually just the ISS) using the SGP4 propagation method implemented in C++.
My question is:
What is the accuracy of the satellite position in the supplied TLEs in terms of kilometers or error % ? And also if it is possible to estimate the error of the satellite's position after propagation with using SGP4 for a given time interval ?
Any sources or references supporting the answers would also be very much appreciated.
It is really not important for the error estimation to be precise and result of a rigorous analysis. But it should be based on some valid assumptions.