Happy Two Pi(e) Day 2025!

It's that time of year again folks! By which I mean Tau Day, 6/28, and Michael Hartl's annual State of the Tau update. Looking back over my blog, I realize this marks ten years since I made my first post on Tau Day back in 2015 (with one every year since except for 2017, where I seem to have simply forgot).

Since you're probably tired of me explaining over and over again why \(\tau=2\pi\) is a more natural circle constant than \(\pi\), let me instead share some (photos of) actual pies. You see, up in the Puʻu Makaʻala Natural Area Reserve where I work a lot of plants are busy producing various fruits over the summer. Two of those happen to be the native Hawaiian raspberries (Rubus hawaiensis), known as ʻākala, and the native Hawaiian blueberries (Vaccinium reticulatum & V. calicynum), known as ʻōhelo (though they're actually red in color).

ʻŌhelo and ʻākala are both edible, though neither are particularly sweet (and ʻākala in particular can be very tart). Last month someone at work suggested the idea of baking them into a pie (where some added sugar could combat the tartness), and this inspired me enough to go out, buy a pie pan, and make some practice pies. I used a recipe for blueberry & raspberry pie (which I'm pretty sure I made while I was in Australia), using store-bought berries to stand in for the Hawaiian versions.

Before baking…

…and after!

And I think it came it pretty well! This is the second of two practice pies I made, since the berries I bought turned out to be just enough for two. The top cover design is meant to be a stylized view of a D20 die (or icosahedron), since we're the 20th domain in NEON and often abbreviated D20 (and have shirts with such a design on them). This was my first time making my own dough (I just used pre-made pie crusts in Australia), and while I think it could be slightly tweaked and improved I'm pretty happy with how it came out (both visually and taste-wise!).

I haven't had much time to collect berries from the field the past two weeks, but this week should provide me opportunity. Yesterday a friend of mine sent me a picture of an ʻākala pie from another conservation team on the island, so I'm clearly not the only person experimenting with it. A hui hou!

He hōkū hou: catching nova V462 Lupi

I didn't quite get this post out on the solstice, but I do have some astronomy-related news! On June 19th I saw a Sky & Telescope article about a newly-discovered nova in the constellation Lupus, V462 Lupi. As a quick reminder, a nova happens when a white dwarf accretes enough hydrogen from the atmosphere of a companion star that it ignites in a thermonuclear explosion, causing the white dwarf to brighten by millions of times (though usually leaving it intact). “Nova” is simply Latin for “new” as the resulting brightening looks like a new star among the fixed denizens of the night sky (and “he hōkū hou” in the title is simply Hawaiian for “a new star”).

After V462 Lupi was discovered on June 12th at a magnitude of 8.7, by the 19th it had brightened up to a naked-eye visibility of around 5.5. I've managed to catch Uranus by eye at around that magnitude from the Visitor Information Station before, so on a whim I decided to head up on the evening of the 20th to see if I could catch this nova. (The AAVSO light curve showed that it seemed to be plateauing, so I figured it might start to fade soon and I wanted to catch it before it did.)

The weather wasn't fully cooperating, as there was a faint high-level cloud layer to the south where Lupus lay along the Milky Way. Visibility was pretty good, all things considered, but everything was just slightly blurry from all the water vapor in the air. I could make out the broad strokes of the dusty rifts in the Milky Way, but none of the fine filamentary structure. Thankfully there was no Moon (something I forgot to check beforehand), which let me see the zodiacal light in the west as the Sun sank below the horizon from my perch atop Puʻu Kalepeamoa.

While I wasn't able to see the nova, thanks to modern technology I was able to capture it in a five-minute exposure with my Google Pixel phone. (I continue to be impressed at the astrophotography capability of this phone, as you may remember from my excursion to catch comet Tsuchinshan-ATLAS last year.) It's not the most beautiful picture of the night sky I've seen, but considering the quality of the seeing it had to work with it's remarkable it came out as well as it did.

Ta-da!

Oh, you can't see the nova? Yeah, me neither. There are far too many stars visible – I'm not sure what the limiting magnitude is, but I've found stars as faint as magnitude 9.5, so there are a lot more stars here than you could see with the naked eye. Let me notate the constellations visible in this photo…

All right, that's better! (I've taken a few liberties in drawing the asterisms.) At least we know where we're looking now. I had to aim by trial-and-error so I didn't manage to center Lupus in the shot on this try, but the nova is in view. It's near where the arm of Centaurus approaches Lupus, around that triangle formed by Delta Lupi, Beta Lupi, and Kappa Centauri, so let's zoom in…

…way in. Just north of the triangle I mentioned is another little triangle of stars (I've marked both in orange in this image to distinguish them). And just north of that triangle's eastern (left) tip is our nova! That eastern star in the little triangle is magnitude 5.8, and it looks like V462 Lupi was about as bright at the time. That would probably have been visible had the sky been clear, but them's the breaks in astronomy; we can't fight the weather, merely live with it. My retinas probably collected a few photons from it over the time I spent staring in that direction, and I'm primarily happy that I got a photo I can share.

And if we go back to the wide-field annotated photo, I caught a few bonus deep-sky goodies in Centaurus! Omega Centauri shines brightly where I've circled it, and inspection reveals the fuzzy, non-stellar nature of this massive globular cluster. Even more impressive, however, is that a five-minute exposure with my cell phone camera shows a hint of the active, unusual galaxy Centaurus A, at a respectable 11–13 million light-years away! (I've imaged both of these objects before, if you want to see what they look like up close: Omega Centauri, Centaurus A.)

Anyway, that's my little near-solstice adventure this year. It's always fun to be reminded of changes in the heavens, especially when they're (theoretically) visible to the naked eye! A hui hou!