Catching Comet Tsuchinshan–ATLAS

Tuesday evening I drove up Maunakea to the Visitor Information Station to see if I could spot Comet C/2023 A3, a.k.a. Comet Tsuchinshan–ATLAS. I hadn't felt particularly motivated to get up before dawn to see it earlier, but now that it's in the evening sky I figured I'd see if I could spot it.

For an astronomer, I'm a little embarrassed at how few comets I've actually seen. While solar eclipses (which I actually have never seen) either land in very out-of-the-way places or come at inconvenient times when I'm scrambling not to spend money on travel, I haven't lacked for chances over the past few decades to see comets (though a few, like Comet NEOWISE in 2020, did come at times when I wasn't really able to get somewhere dark enough to see them). Still, I don't have much excuse for missing Comet McNaught in 2007 or Comet Lovejoy in 2011. I did see Comet Holmes' remarkable brightening in 2007, though that was an unusual comet since we were seeing it almost head-on, so it didn't really display much of a tail. There are probably a few more I missed in that time span as well which I've forgotten; on the whole, I have a pretty poor track record of seeing naked-eye comets even when presented with the opportunity.

Which is why I found myself yesterday trudging up the path to the top of Puʻu Kalepeamoa in some extremely strong (and frigid) winds, setting up my GoPro for a timelapse, and waiting for the sunset. The timelapse didn't quite work out as planned since it failed to adjust the exposure time properly after it got dark, but I managed to get some photos, at least. 

The setting Sun through a māmane tree. They're in bloom this time of year.

The nearly-full Moon, unfortunately, wasn't doing the comet any favors as it lit up the night sky. I was first able to make it out maybe a half hour after sunset, then as twilight faded it became easily visible for perhaps another hour or so; by the time I left, nearly two hours after sunset, it was getting low enough on the horizon to be difficult to make out again.

Comet Tsuchinshan-ATLAS over Hualālai, with Venus at left.

With that, I can finally say that I've seen a proper, honest-to-goodness hairy star, and I have the pictures to prove it. Speaking of, I got those shots with my Pixel 7 Pro; not as good as a professional camera, but it's still remarkable to me just how good the software and hardware in phones has gotten, that it can capture shots like this in low light. (I did set it up on a tripod for stability, but still.)

Overall it was an interesting experience, and I'm glad I made the effort to see it. (Though after sitting out in those winds, maybe I should've gotten up to see it before dawn from Hilo, where it'd be warm[er] and humid instead of frigid and parched…) It should still be visible for a little while, perhaps the next few weeks; the Moon will start rising later and it'll be getting higher above the horizon, which will both make it easier to see, but it's also receding from the Sun which will make it get fainter, so there's a tension between the various effects. The next few days should still be good, though, and I'd recommend making the effort if you haven't seen it. I probably won't head up Maunakea again, but I'll try to keep an eye out for it from Hilo as it rises high enough now to be seen above the western horizon. A hui hou!