NOTE: This post is actually being posted in December since, as I was writing my year end summary, I realized I never posted these observations!
One of the Big Goals of this project is eventually follow Kepler’s methods to be able to derive the orbit of the planets. While I’m still nowhere near being ready for that as I’m still working on the Almagest, I know enough that I know the key observations are those taken when the planets are at opposition. Thus, the quadrant was originally built in time for the 2018 Mars opposition. But Mars only comes to opposition a little over once every two years.
And it’s now time for another opposition. Since I’ve been having some issues with the recently added azimuth ring, I wanted to make sure they were resolved before the opposition. Thus, I went out a few nights before opposition to see if I’d successfully resolved the issues. That night (10/9), I observed $29$ stars plus the three visible planets (Jupiter, Saturn, and Mars). As usual, a few of these observations got tossed, but the overall data looked pretty good. The average right ascension averaged $0.20º$ low and the declination came out $0.16º$ low which is fairly average. Unfortunately, I didn’t catch any new stars as this portion of the sky is pretty well mapped.
Then came the $13^{th}$ which was the important date of opposition. While waiting for Mars to get to a decent altitude, I was able to take observations of $20$ stars that I kept as well as Jupiter and Saturn.
Coming to Mars, I ended up taking $10$ readings in hopes it would average out well. Ultimately, the average for Mars came out with the right ascension being low by $0.11º$ but $0.44º$ low on the declination.
The overall data for the night wasn’t much better, but actually went the other way: The average right ascension was $0.41º$ high and the declination averaged $0.14º$ low.
As usual, the data is available in the Google Sheet.