Last month, I came across this dark sky finder website. Unsurprisingly, dark skies in the Eastern half of the US are fairly hard to come by. However, Mark Twain National Forest in southern Missouri puts a significantly large dent in light pollution that much of the surrounding area is quite dark. Sadly, as the name suggests, the forest doesn’t have many clear sites suitable for astronomical observing, but I was able to find a campsite that’s part of the Rocky Creek Conservation Area that what looked to be a large field based on Google Maps that sat in the dark area.
This weekend I found someone to take over my herald duties to Their Majesties and made the 2.5 hour drive to check it out.
The field ended up being only partially mowed, with thick weeds a few inches tall, but still easily manageable for the quadrant. So I set up and shortly before 10pm, was ready to start observing, just as Jupiter crossed the meridian.
The dark sky conditions of the site were quite good. We were easily able to see past 5th magnitude. Probably closer to 6th using averted vision. However, the bigger trouble was the humidity. Even as we arrived, shortly before sunset, there was already a thick mist over the field that consistently grew thicker as the night progressed. While this was low enough to the ground that it didn’t obscure the stars, it did mean that simply breathing caused my glasses to fog up. As such, observing because a game of trying to observe as quickly as possible while aligning the quadrant.
Regardless, I was able to get observations of 49 stars in just over 3 hours, as well as Jupiter and Saturn.
| Object | Alt | Az | ST | Dec | Error1 |
| Jupiter | 30.4 | 180 | 17:00 | ||
| η Oph | 36.8 | 180 | 17:14 | -16.03 | -0.31 |
| 36 Oph | 25.9 | 180 | 17:17 | -26.94 | -0.33 |
| ν Ser | 39.6 | 180 | 17:24 | -13.24 | -0.39 |
| θ Oph | 28.3 | 180 | 17:26 | -24.54 | 0.46 |
| υ Sco | 15.7 | 180 | 17:33 | -37.14 | 0.16 |
| λ Sco | 15.9 | 180 | 17:36 | -36.94 | 0.16 |
| ξ Ser | 37.7 | 180 | 17:39 | -15.14 | 0.26 |
| θ Sco | 9.4 | 180 | 17:41 | -43.44 | -0.44 |
| β Oph | 56.5 | 180 | 17:45 | 3.66 | -0.91 |
| κ Sco | 14.7 | 180 | 17:47 | -38.14 | 0.89 |
| ι1 Sco | 12.7 | 180 | 17:51 | -40.14 | -0.01 |
| G Sco | 15.9 | 180 | 17:52 | -36.94 | 0.10 |
| ν Oph | 43.5 | 180 | 18:01 | -9.34 | 0.43 |
| 68 Oph | 53.7 | 180 | 18:04 | 0.86 | -0.44 |
| 72 Oph | 62.7 | 180 | 18:11 | 9.86 | 0.30 |
| μ Sgr | 31.6 | 180 | 18:16 | -21.24 | -0.18 |
| η Sgr | 15.7 | 180 | 18:19 | -37.14 | -0.38 |
| δ Sgr | 23.8 | 180 | 18:23 | -29.04 | 0.79 |
| η Ser | 49.7 | 180 | 18:25 | -3.14 | -0.24 |
| ε Sgr | 18.4 | 180 | 18:26 | -34.44 | -0.05 |
| λ Sgr | 27.7 | 180 | 18:30 | -25.14 | 0.28 |
| α Sct | 44.4 | 180 | 18:37 | -8.44 | -0.19 |
| δ Sct | 43.5 | 180 | 18:45 | -9.34 | -0.29 |
| φ Sgr | 26.3 | 180 | 18:48 | -26.54 | 0.45 |
| β Sct | 48.3 | 180 | 18:49 | -4.54 | 0.21 |
| θ1 Ser | 56.7 | 180 | 18:56 | 3.86 | -0.34 |
| σ Sgr | 26.5 | 180 | 18:58 | -26.34 | -0.04 |
| η Sct | 46.9 | 180 | 18:59 | -5.94 | -0.09 |
| ξ2 Sgr | 31.6 | 180 | 19:00 | -21.24 | -0.13 |
| i Aql | 46.5 | 180 | 19:03 | -6.34 | -0.60 |
| ζ Sgr | 23.0 | 180 | 19:06 | -29.84 | 0.04 |
| λ Aql | 47.8 | 180 | 19:07 | -5.04 | -0.16 |
| ο Sgr | 30.7 | 180 | 19:10 | -22.14 | -0.40 |
| τ Sgr | 25.2 | 180 | 19:12 | -27.64 | 0.03 |
| Saturn | 30.6 | 180 | 19:13 | ||
| π Sgr | 31.5 | 180 | 19:13 | -21.34 | -0.32 |
| d Sgr | 33.5 | 180 | 19:20 | -19.34 | -0.39 |
| ρ1 Sgr | 35.4 | 180 | 19:23 | -17.44 | 0.41 |
| υ Sgr | 36.9 | 180 | 19:25 | -15.94 | 0.02 |
| δ Aql | 56.8 | 180 | 19:28 | 3.96 | 0.84 |
| ν Aql | 53.4 | 180 | 19:29 | 0.56 | 0.22 |
| e Aql | 50.2 | 180 | 19:32 | -2.64 | 0.15 |
| ι Aql | 51.7 | 180 | 19:39 | -1.14 | 0.15 |
| σ Aql | 58.1 | 180 | 19:41 | 5.26 | -0.14 |
| γ Aql | 63.5 | 180 | 19:47 | 10.66 | 0.05 |
| α Aql | 62.2 | 180 | 19:53 | 9.36 | 0.49 |
| η Aql | 54.2 | 180 | 19:55 | 1.36 | 0.35 |
| β Aql | 59.2 | 180 | 19:56 | 6.36 | -0.04 |
| θ Aql | 52.2 | 180 | 20:12 | -0.64 | 0.18 |
| α2 Cap | 40.7 | 180 | 20:21 | -12.14 | 0.40 |
| Average | 0.02 | ||||
| StDev | 0.38 |
The standard deviation for the night was a bit higher than usual. I attribute a large part of this to difficulty in sighting many of the stars. Part of this was due to the condensation on my glasses forcing me to take less time than usual to really sight in on the stars before my vision was entirely obscured.
But another difficulty was the faintness of the stars. Out of the 49 stars observed, 31 of them were ones that I haven’t observed before, often because they were well past 4th magnitude and not visible at other sites. However, even at a nice dark location, it was still difficult to observe them and I had to star developing new techniques to sight using averted vision.
Yet for all the scatter, the average came out to an impressively low 0.02,
Although I don’t get into the error in RA in these posts2, the observations were consistently taken just about 2 minutes late. I believe this is because when the quadrant was aligned on the north star, the north star was about 0.23º to the right of the actual meridian. Transforming that to minutes off is 1.5 so we’re in the ballpark. However, I should note that this error was extremely consistent whereas in previous observing sessions, I have had difficulty determining when an object was truly on the meridian. But the consistency last night suggests this is finally resolved.
Since my last set of observations, one of the things I realized is that the sights on the quadrant, which proved near useless for determining altitude, end up being quite good for determining when an object is on the meridian. However, the trouble is that the far one is a dark object against a dark sky. But I recalled that in one of the illustrations from Tycho’s books, there was a nearby assistant with a candle that recorded the observations. As such, I thought it fair game to illuminate the sight with my red headlamp which makes it visible without ruining my dark vision, and quite easy to see when the star was aligned on the meridian.
So overall it was an extremely good night for observing. Next month’s new moon falls around Cattle Raids which I’m unlikely to want to attend due to the distance, so there’s a fair chance I’ll be doing another observing night. Although I’m not sure I want to drive all that distance every time. That being said, I’m leaving in 5 days for Pennsic and the quadrant may be coming with me. Right now the weather isn’t looking great for observing, so it might stay behind. But the moth following that, I’ll be hosting Gryphon’s Fest here in the Barony of Three Rivers and hope to get some observing done there as it will be hosted at the park that the astronomical site I use most frequently is part of.