Users familiar with console tutorial #3 will have noticed that the self-consistent 2-planet fit to the remarkable multi-planet system orbiting GJ 876 is presented as a fait accompli. We are currently implementing an “epoch” slider for the console which will greatly smooth the transition from Keplerian to Newtonian fits for interacting systems, but amazingly, it turns out to be possible to obtain a competitive 3-planet fit to the Rivera et al (2005) GJ 876 data set using only the current version of the systemic console. This post gives the details, and gets a bit technical, so if you are interested in following it closely, we suggest that you first work through tutorials 1, 2, and 3.
Also, a cautionary remark. The 3-planet integrated fit requires patience. I was able to get the fit described below in about 2 hours on a machine with two 3.4 GHz Intel Xeon CPU’s (with hyperthreading turned on). Thus, I was able to use the other CPU’s to do other work. On single-core, single-processor machines, the systemic console will hog the CPU (unless it’s niced and put in the background).
In any case, here’s the 411: