Data: Stellar Quadrant Observations – 8/24/19

Life has been eating me pretty heavily lately so I haven’t had any time to work on the Almagest, and barely any time to observe. But last weekend, I took the quadrant to Baroness Wars over in the Midrealm. The location wasn’t all that great. The dark sky map said it was like being in the suburbs of St Louis, and the fact that they left some lights on illuminating a racetrack or something next to the county fairgrounds we were in also sucked, but I was still able to get a few observations in over the two nights I was there.

Object Alt Az ST Dec Error1
Saturn 27.95 180 19:11
ζ Sgr 20.4 180 19:15 -30.05 -0.17
δ Aql 53.3 180 19:31 2.85 -0.27
γ Aql 61.0 180 19:53 10.55 -0.06
α Aql 59.4 180 19:58 8.95 0.08
η Aql 50.9 180 20:02 0.45 -0.56
γ Sge 69.8 180 20:08 19.35 -0.14
θ Aql 49.6 180 20:19 -0.85 -0.03
α2 Cap 37.7 180 20:20 -12.75 -0.21
β Cap 35.05 180 20:28 -15.40 -0.62
ε Del 61.7 180 20:40 11.25 -0.05
β Del 65.1 180 20.44 14.64 0.05
α Del 66.55 180 20:49 16.10 0.19
ε Aqr 41.1 180 20:55 -9.35 0.15
ν Oph 40.4 180 18:04 -10.05 -0.28
γ Sgr 19.95 180 18:08 -30.50 -0.07
72 Oph 59.8 180 18:14 9.34 -0.22
μ Sgr 29.5 180 18:22 -20.95 0.11
η Ser 47.3 180 18:30 -3.15 -0.25
λ Sgr 25.4 180 18:32 -25.05 0.37
Average -0.10
StDev 0.24

One of the things I noticed when putting the data in is that I was consistently several minutes late (as in 5-8 minutes) in judging when objects were on the meridian. Some of this can be explained by aligning on the north star as it was almost at its full distance east of the meridian, meaning that I would be judging objects in the south when they were past the meridian. But assuming I was perfectly aligned on the north star, that can only account for about 2m40s of that difference.

If you’ve followed the observational posts, you’ll see that judging when an object is right on the meridian has long been a problem. Formerly, we were consistently too early. To try to solve this, I’ve been using the sights on the instrument which we formerly abandoned. While they’re still certainly no good for judging altitude, seeing if the star is lined up left to right is much easier.

But given the consistent late measurements I’ve had the past few times using this quadrant, my suspicion is that they’re slightly misaligned. Thus, I think I’ll go back to the previous method of just trying to determine it by looking down the edge of the quadrant arm.

In addition, the error in the declination creeped up a bit this time. It’s still in line with long term averages.

  1. Error is vs modern published values and only for Dec.