Tuesday, January 28, 2014

Snagging a Supernova (SN 2014j)

Last week Tuesday, January 21, an astronomer at the University of London Observatory was teaching some undergraduate students how to run the CCD imager on a 14-inch telescope during a short break in the clouds. At about 7:20 PM local time, they noticed a new star in the nearby galaxy Messier 82. This star did not show up in archival images of the galaxy, and after using a second set of equipment to make sure it wasn't an artifact they realized they were dealing with something very real. It turned out to be the closest type-Ia supernova in 42 years, and was duly designated SN 2014j.

Messier 82 is a funny-looking galaxy located at a distance of about 11.5 million light-years away, close to another galaxy called Messier 81. They're practically next door in galactic terms – only 6 times further away than the Andromeda Galaxy – and are easily visible in moderately sized telescopes.

I know this personally both because I've seen them before at the Vis, and because I went up there Sunday night in order to try to get an image of the supernova. When I got there I discovered some bad news: I couldn't get the telescope mount to connect to the control software on the computer (probably a cable went bad). The telescope mount still had its built-in control software, so on a whim I polar-aligned it as best I could then told it to go to Capella, the brightest star close to M82. Amazingly, when I took a short exposure with the CCD Capella was visible on the first try. I then tried sending it to M82, and while that wasn't visible in the resulting image, its neighbor M81 was. Finally, after some touch-and-go work manually directing the telescope with its built-in directional controller I was able to get both M81 and M82 (supernova easily visible) in the same frame.

Having miraculously overcome the first major hurdle of finding the target, I was left with the sad reality that without being able to connect the mount, I couldn't get auto-guiding going, which meant that exposures longer than about 12 seconds started to show unmistakable signs of star trails. This kept me limited to short exposures. The resulting picture is hideous, not helped at all by Blogger's re-scaling of the limits. I'm a bit embarrassed to be showing such a poor piece of work, but it's a supernova, I simply can't refrain from talking about and showing it. Here's the picture I got, with M81 the blur at the top, M82 the blur at the bottom, and SN 2014j marked by the tiny straight lines.

I looked back through my blog and saw that I've never imaged this pair of galaxies before, so for the record M81 is actually a lovely face-on spiral galaxy, while M82 is...odd. It's apparently a spiral galaxy too, but it's almost edge-on to use, and it has these really weird filaments of dust in front of it in optical light. (You can kind of see the thickest of them in the image near the middle of the galaxy, as a dark bar that bisects it.) These filaments often make it look as though the galaxy is exploding in long exposures, and it has the amusing nickname of the Cigar Galaxy due to its shape in small telescopes.

I hope to get a better picture of these beautiful galaxies and perhaps the supernova that graces one of them, but my near-future plans have been put on hold by the arrival of a large storm system bringing snow and cloud cover to Mauna Kea. The forecast is bad through the weekend at the moment, but, as always, we shall see...

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