Monthly Archives: March 2014

What was that satellite?

While looking at the M82 Supernova last night I saw a satellite. What was it?

I can’t find a tool that solves this problem. There’s a zillion tools for finding where you can see any specific satellite or when there’s likely to be a show overhead. And several tools draw all the bright satellites visible at a given time so you can go back in time and find them. But this wasn’t a bright satellite, only saw it in the scope, and I’m curious what it was.

I saw it around 9:05PM California time on March 11, 2014. It was very near M82, I’d guess about 0.3° either left or right of it. And moving top to bottom, roughly parallel to the cigar shape. It was noticeable but not terribly bright, maybe magnitude 10 or so? That’s a total guess. It was fast, crossed my 1° FOV in maybe 10 seconds. So a low orbit presumably, and given I saw it in the north I’d say polar.

Update: Satellite Safari will render satellites at any given time and has enough entries in the database to be interesting. It doesn’t include M82 as a visual reference but you can kind eyeball the space between d UMa and EN UMa. Still, nothing visible at that time and place. Calsphere 4A made a pass somewhat nearby at 9:02 PM but I don’t think it’s close enough to be what I saw.

How many satellites are there in orbit anyway? Wisegeek says 3000 and a total of 8000 man-made objects in orbit, and a total of 24,500 in all time. UCS lists 1084 operating satellites. Most projects get their data from Celestrak; their master table has some 6000 entries and the full catalog has 39,591 rows in it, here’s some basic statistics. Satellite Safari’s rendering database seems to have 1600 items in it. Stellarium’s satellite plugin has 823.

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M82 Supernova

I finally got to see the new supernova in M82, properly known as 2014J. Not easy to find; both M82 and M81 are far away from any particularly visual landmarks. I finally found it by going diagonally across the Big Dipper from Phecda to Dubhe and then doubling that. Then getting lucky and finding the vertical cigar.

I had the best luck finding M82 with my 25mm eyepiece and its sharp 1° FOV. A little less impressed by my new Televue Ethos 8mm; the 0.7° FOV makes it harder to find things and the image seems a bit soft. Very hard to dial in the focus I guess, but that cheap 25mm Plössl is so sharp it’s a joy. Once found I could use all my eyepieces of course, and even the 7.5mm Plössl seemed better than the fancy 8mm Ethos. Although it was definitely a dimmer view.

Anyway, I found M82, but I had a hard time spotting the supernova. Only brief glimmers of it, honestly looked like it twinkled into view briefly, and if I didn’t know exactly where to look I’d never have clocked it. Apparently it’s at magnitude 13 now so no big surprise, I was foolish to wait so long.

I wonder how to understand the visually apparent brightness of a fuzzy object like M82? It’s listed as a “visual magnitude of 8.4 and a surface brightness of 12.8”, which apparently is a very bright surface brightness. Does that mean that when viewed at low magnification the point is magnitude 8.4, but when viewed wide and spread out the average magnitude is 12.8? And is there any contrast at all for a magnitude 13 supernova embedded in that? The earliest images call out the supernova at magnitude 14.4 and there’s definitely some contrast, but only because it’s in a dark part of the galaxy.

I continue to be disappointed with how wan galaxies look like in a telescope compared to the fancy pictures. Not a lot of reward compared to fancy astrophotography. The best thing for me was seeing M81 and M82 in the same frame (in the 25mm eyepiece), seeing the two together and understanding their relationship is cool.

Here’s the light curve for Supernova 2014J. I really should have made the effort to see it at its brightest. It astounds me that something as arcane as a supernova explosion happens on a human timescale of days instead of in milliseconds or millenia.

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