2021-11-03, 08:10 PM
Thanks. I played with your suggestion. For the comets I tried, the difference in position for November 2nd was only a few arc seconds using epoch date elements from Sept 17, 2021 and current from JPL/Horizons. So yes, little need, but then I'm an experimenter by heart and always will be. The same experiment with small rocks proved a bit different. But hardly worth plotting as the difference was just 15 arc seconds.
Very time consuming but hey, I'm retired ;=)
Very time consuming but hey, I'm retired ;=)

