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.

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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More DSLR disasters

Such amazing night skies with the weather, I pointed my DSLR up. 28mm fixed lens, ISO 800, f/2.5, exposures of 10-30s. Nothing great came out of it (no surprise), but some photos on Flickr (lower res images below). I’m amazed at how big a difference having the moon up makes, even when it’s a very dry night and I’m shooting photographs 150° away from the moon.

This old Canon Rebel XT is probably past its prime, I bet I could get much better results with a newer sensor. I’m tempted to try my little pocket Canon S100 tonight; it’s a tiny sensor, but it’s new and good at low light and CMOS might do interesting things the old CCD won’t. Worth a try at least. I did at least solve the lens focus problem on the last two shots; I focussed on the edge of the moon! There’s nothing bright enough for the autofocus to grab onto without the moon though.

Wide angle shots of the night sky are not particularly interesting without context, I understand why all the arty shots involve something in the foreground like a picturesque barn or something.

 

Milky Way (with moon)
Orion (moon up)
Milky Way (no moon)

New eyepiece

So after a few months’ enthusiasm I lost interest in the backyard astronomy. Through the summer, sadly. As warm as it is it doesn’t get dark until late, and it’s still hard to find stars and see things and I got frustrated. But then we had perfect weather and a friend of mine got a scope and that inspired me to bring out the 8″ Dob again and hey look, there’s some stars!

To bolster my new-found enthusiasm I succumbed to the nagging desire I’ve had since I got the scope to buy a fancy eyepiece, in particular a Televue Ethos 8mm with a 100° apparent field of view. I got sucked in by the marketing and reviews about “falling into the dark sea of stars” when looking through the thing.

It is quite nice, although it’s not as transformative as I’d hoped. There’s still the uncomfortable feeling of squinting through a tube with one eye closed. But boy it’s wide and bright and zoomy. I like it quite a bit and it will instantly replace my old 7.5mm Plössl. I’m also hopeful it can replace the 25mm Plössl for many things.

Objectively, on the 8″ Orion Dob the Ethos gives me 150x magnification with a 0.7° field of view. Compare 160x and 0.3° with a 7.5mm Plössl, or 48x and 1.0° with the 25mm Plössl. Subjectively, the Ethos feels like I can look around about as well as I did with my old 25mm Plössl eyepiece. I’d given up on the 7.5mm Plössl; so narrow, so zoomed in, even when I found the object I wanted to see it was out of view too fast to enjoy. I was able to quickly find Jupiter and the Orion Nebula with the Ethos, something hopeless with the high zoom Plössl. The Pleiades weren’t so impressive though, just too narrow a view to see the 1.5° square cluster.

My main complaint is it’s so heavy and expensive I’m a bit nervous. Orion’s Dobsonian mount is stiff enough the scope is still stable, but I’m scared I’m going to drop the thing. Also the way it sits in the 1.25″ focusser with a single lock screw feels flimsy. (Despite having a 2″ fitting the eyepiece is truly a 1.25″ bit of optics.)

It took me awhile to pick the right eyepiece; I knew I wanted a fancy Tele Vue wide FOV eyepiece but wasn’t sure what their products really were until I found the specifications page. The advice for Dobsonians page was also useful. I picked the $550 Ethos over the $300 Nagler / Delos because every review I read said the extra FOV was worth it. I considered getting the 10mm instead; the field of view is closer to the 1° I’m used to with the 25mm Plössl. But the advice page made me think ahead to when I get the next eyepiece, and the 13mm is an appealing increment over the 8mm. Also the 10mm is a relatively new and unusual product, I figured the 8mm had the kinks worked out and more resale value.

So after 20 minutes using it too look at easy targets, yeah, I’m impressed with the Ethos eyepiece. If I were worried about money I’d consider the Naglers instead; slightly less FOV but half the price! But the Ethos is lovely and I imagine I will quickly be spoiled by its generous view.

Next up on the gear lust list: a GoTo mount. I know finding stars manually is half the fun in backyard astronomy but I just don’t like it. Need to read up more on whether stepper motors on a simple Dobsonian really tracks reliably. It seems like it should, but so much development is behind equatorial mounts I have to assume they are better. Alternately I’d like a better finder scope for manual finding; the reflex sight is just not good enough. At about $40 for an 8x spotter scope it seems like a simple upgrade compared to motorized mounts.

Comet PANSTARRS

Finally got a clear night and was able to find PANSTARRS. It was about 15° following the sun, so lots of room to wait for it to get dark before finding it. And it’s reported to be pretty bright, maybe 1–2? Even so there was no way I could see it with naked eye; only found it by scanning around with binoculars. There it is though, tail pointed up.

I was living in Santa Fe when the Comet Hyakutake was up and it made a huge impression on me. I remember it being big, and bright, and easily visible up high in the sky even at 10pm. PANSTARRS is disappointing in comparison.

I wonder if someone keeps charts of apparent comet brightness? They must.

 

Horizontal vs Celestial Coordinates, Polaris

I’m trying to understand the relationship of horizontal coordinates (altitude, azimuth) and the celestial coordinate system. One thing I’d not appreciated is the altitude of Polaris, the north star, is pretty much always at a fixed elevation. Its Declination is 89° 15′ 50.8″, or about 90° (at the celestial north pole). And at my house at 39.2°N it’s pretty much always at altitude 39.2° above the horizon. I guess that sort of makes sense, it’s the only way it makes sense as a North Star, but I’d never really noticed it before and naively thought Polaris’ elevation would change with the seasons.  Maybe because its at the tip of the little Dipper which does rotate with the seasons, and when the bowl is higher in the sky it feels like Polaris is too.

This makes determining your latitude in the northern hemisphere pretty easy; just site the north star and measure its angle from the horizon. Preferably in calm seas with clear skies.