This week’s weather was supposed to be dismal. And for many of my friends, it was. The derecho that ripped across the midwest left many people in the kingdom without power for several days. However, for me, it pulled the clouds that were supposed to last through the weekend out early, leaving me with a cloudless friday night with a waning crescent moon. About as good as I can ask for for observing. However, the humidity did linger with humidity readings upwards of 70%. While it didn’t feel uncomfortable due to the reasonable temperatures (low 70’s), it did mean that my glasses fogged quite badly and all the paper I take notes on was soggy by the end of the night. Despite that, last night was easily the most productive night I’ve yet had. I totalled 71 stellar observations and 3 planets.
However, the average quality of the data was somewhat worse than usual. Somehow I managed to average 0.37º low in declination and 0.63º high in right ascension. The standard deviations were in line with what I’ve had previously1. It’s hard to say what drove this.
My initial feeling was that it has to do with technique. Overall, I’ve found it extremely difficult to try to determine both the altitude and azimuth at the same time. So my technique has been to first find the altitude, use a clamp to lock that in, and then line up the azimuth. In general, I’m fairly quick to do both of these; many of my readings were 2-3 minutes apart. To help account for this, when I get the sidereal time from the app on my phone, I always round down 1 minute which should generally be a point in time between when I took the altitude and when I took the azimuth. This would mean that I should be a tiny bit high on altitude on average2. But I’m seeing the exact opposite. Instead, I’m consistently low when I’m in the western sky. And I’m consistently high when I’m in the eastern sky.
So I think the issue was that the quadrant wasn’t quite level. I know when I set it up, it was not on particularly level ground. The base has blocks I can shove under it as well as screws for fine adjustments, and it was initially pretty level. However, I could tell that it didn’t stay that way as the blocks likely sunk into the soft grass.
I’d checked the position of the azimuth ring several times throughout the night, so I’m quite sure that wasn’t a major factor. As such, the leveling is the only explanation I can come up with.
Still, the night added a ton of new data. Some constellations I’d barely had a single star in are now well mapped. There was so much progress I went ahead and plotted the data out and drew the constellations on again. The last time I did so was for Kingdom Arts & Sciences last year, so I figured it was time for an update!
All together, there should be a little over 300 stars plotted here. We can really see the summer sky is coming along. Many of the main constellations are well fleshed out. There’s still a gap to the right from consistently poor observing in spring, but hopefully we’ll get that remedied this coming year. Also filling out is the area from 30º declination upwards which was previously too close to the zenith to get regularly. Overall, I’m quite pleased!
- Being 0.52º and 0.42º respectively.
- This is because most of the night I was working in the western sky, picking up constellations that are close to the zenith when on the meridian and thus, not easy to get. Since these constellations move “down and right” as they set, since I took the altitude first, I would have had them higher than they were when the sidereal time was recorded.