As usual, the weather in January and February of this year hasn’t cooperated. Nights were consistently cloudy during good moon phases or the temperatures well below freezing.
But as March has rolled around, temperatures have begun to warm, and the forecast called for a clear night with a good moon phase so Yseult and I headed out to Danville Conservation Area to do some observing.
Driving out, there were a few scattered clouds with about $50$% sky cover. This didn’t improve as we got there and set up, with sky cover increasing and worse, some clouds just hanging in the north where we needed to see the north star to align. We waited for well over an hour and were about to call it quits at 7:45pm, when the clouds started breaking up. A lone star was visible in the portion of the sky that I expect the north star, but without being able to see the big dipper or other reference points, we weren’t initially sure it was the right one. To verify, we measured the altitude of the star and it matched what we’d expect1, so we decided to go ahead and observe. Fortunately, the skies slowly cleared and by the time we called it quits around 10:30pm, they were mostly clear.
The intent tonight was to try to fill in some of the sky between Orion and Leo as there’s a large gap in the star map that has persisted. This stems largely from the fact that, until this past summer, the quadrant could only observe objects as they transited the meridian and that patch of sky transits in the evenings of January and February which, as I mentioned above, don’t tend to have good observing weather. Secondly, many of the stars in this patch of sky are $4^{th}$ magnitude or fainter making it a challenging section of sky to map anyway.
To begin the night, we started in Canis Major. While we could just make out stars fainter than $4^{th}$ magnitude, we couldn’t see them well enough to be able to sight them reliably, so ended up wandering our way through Orion and Taurus. Ultimately we made $58$ observations of $46$ unique objects2.
When processing the data, it was immediately obvious there was an issue: The right ascensions were skewing a full degree low. This is often a sign that our alignment on north was off since we base it on the north star. Checking Stellarium, it turns out when we lined up a little before $8$pm, Polaris was as far to the left of the meridian as it gets, meaning our alignment was off from true north by $0.71º$. Correcting for that, greatly improved the quality of the data.
Overall for the night, we averaged just $-0.19º$ off on right ascension, and $0.21º$ high in declination. Standard deviation was in line with what we often see.
As usual, all the data can be found in the Google Sheet.
I also took the aggregated data and exported it to Excel to map again so we can see the updated map:
The gap still persists, but it is getting smaller!