Geopotential model are used whenever propgation has to be done of the orbit. Geopotential model models the potential of earth via spherical harmonics.
These models are generally published by NASA as measured by mapping missions.
One can easily find geopotential model for earth, moon, mars and venus.
How does one map these geopotential model ?
What technique is used to map gravity ?
Well obviously an orbiting satellites measure zero acceleration when not firing engines as orbit is nothing but free fall.
So how can one map gravity ?
Following is quoted from wiki article about grail mission technique. The answer probably only addressed about earth gravity modelling. I was more interested in gravity mapping of moon and other bodies.
Each spacecraft transmitted and received telemetry from the other spacecraft and Earth-based facilities. By measuring the change in distance between the two spacecraft, the gravity field and geological structure of the Moon was obtained. The two spacecraft were able to detect very small changes in the distance between one another. Changes in distance as small as one micron were detectable and measurable. The gravitational field of the Moon was mapped in unprecedented detail
How can simple change in distance can give the gravity map?