Monthly Archives: December 2012

Las Cumbres Observatory

My old boss Wayne is now helping run a telescope network, the Las Cumbres Observatory Global Telescope Network. Fun stuff; a bunch of scopes world wide, fully automated, with somewhat open access policies. Looks like getting time requires you know someone, but a bunch of their data is available online. Here’s an image search form that lets you search by a portion in the sky. And here’s a result for the Ring Nebula.

l_e_20121124_35_1_1_1_sm

They look to be up and running pretty seriously; 30+ people on the project, two live scopes with a bunch more on the way, papers being published on supernovas and exoplanets. They’re looking for a Director. I wonder how they’re funded; seems mostly private. They’re a 501(c)(3).

NGC 7789 / Caroline’s Rose

Spotted this tonight, first with binoculars and then 48x and then 160x. Prettiest in the highest magnification. I’m glad I read the description in the book about it looking like rose petals; very evocative and definitive. Can’t find a good picture online that looked like what I saw, the brightness compression of digital images destroys some of the structure. Would be a fun object to try to photograph well.

 

M52

Spotted M52 / NGC 7654 tonight, first with the 48x and then the 160x eyepiece. Liked it better at the lower zoom. A bit tough to identify against the bright backdrop of so many stars in the Milky Way. I took the presence of the bright star to lower right (in eyepiece) as definitive. I found it by following the line from Cassiopeia alpha to Cass beta, then hopping the same distance and just a bit to the left. Then scanning with the scope.

Frankly it didn’t look much denser or more interesting than nearby stuff in the Milky Way; I’m curious how this gets identified so clearly as a group. Need more experience.

Fields of view redux

Revisiting my field of view musings, some stats.

  • Binoculars
    10×50: 4.3° = 258′
    30×50: 2.2° = 132′
  • 8″ Dobsonian
    25mm Plössl: 1.1° = 66′
    25mm + 2x Barlow: 0.5° = 30′
    7.5mm Plössl 0.33° = 20′
    7.5mm + 2x Barlow: 0.17° = 10′

M31 (Andromeda) is 109′ x 62′: no wonder I couldn’t see the oval shape! I should try again in the binoculars. And I’m amazed I was able to make out M57 (Ring Nebula) in the 25mm; at 1′ it was less than 2% of my scope’s width.

I was thinking of looking for M52 tonight. It’s about 12′ across, so will fit comfortably in the 7.5mm eyepiece. Also thinking of NGC 7789, 16′ or about the same size.

M31 Andromeda Galaxy

Observation time: 2012-12-28 02:30Z
Conditions: full moon low on horizon, relatively clear but still humid.
Equipment: 8″ Newtonian / Dob, 25mm eyepiece, 48x.

Success! Saw the Andromeda Galaxy. Found it first with binoculars, then later with the scope. Hardest thing I’ve found yet, I keep looking on moonlit nights where even mag 3 stars are hard to spot clearly. I found it by spotting the Square, then beta And and mu And and walking that over to the right area. Finding it first with binoculars was a huge help, I had some idea what to expect. Then with the scope, just methodically scanning the area until I found the fuzzy glow. Really is hard working a Dobsonian mount to track something right at the zenith.

Sort of a disappointing sight; what it looked like to me was just a fuzzy blob with a bright star in the middle, I couldn’t make out any particular oval shape. I wasn’t able to see the other two nearby galaxies; didn’t try very hard.

Stellarium simulated view

Jupiter simulation discrepancies

While trying to understand what I’m seeing on Jupiter through telescope, I’m using software to simulate the view to understand it better. But I’m learning that just because a program shows a rotating image of Jupiter doesn’t mean it’s correct. Every simulator I try shows me different images, and some of them like Stellarium seem flat-out wrong. Here’s an example.

Jupiter will be interesting about 11pm local time tonight (ie: 2012-12-28 07:00Z). I know from this table that there’s a transit of the Great Red Spot that’s centered at 7:06Z, and I know from this calculator that Europa will be making a transit (moon transit: 04:58Z to 07:26Z. shadow transit: 06:12Z to 08:44Z). So I’d expect the image at 07:00Z to show the Great Red Spot, Europa inside Jupiter’s disc, and Europa’s shadow also inside Jupiter’s disc.

But what I actually get is different for different software. Europa is in a different place in different programs; I think that’s because Jupiter is 35 light minutes from Earth right now. So if a program doesn’t simulate the speed of light, it’ll show an image 35 minutes ahead of what I’d see on earth.

But a couple of programs have the Great Red Spot off by several hours. They all simulate rotation, but do some of them have the wrong facing? I triple checked all this and I think I am using each program correctly. In particular I was careful about local time vs. UTC. It seems like a crazy flaw. I’m probably using the software wrong somehow, but I can’t figure out how.

Update: a bit more research shows the GRS position is a known problem, at least in Stellarium. Here’s a fix, you edit the value of rot_rotation_offset in ssystem.ini for Jupiter. Unfortunately editing that file seems to have no effect in Stellarium 0.11.4 on my Mac, I wonder what I’m doing wrong. Interestingly the GRS wanders, it seems to drift about 15° per year. That may explain why Starry Night (below) is close but not quite correct.

Update 2: the file to edit on Stellarium on Mac is ~/Library/Application Support/Stellarium/data/ssystem.ini. I set rot_rotation_offset = 92 and now the Great Red Spot is in the middle of the planet during the transit at 2012-12-28 7:06Z (when Stellarium is set to simulate light speed).

Stellarium

Stellarium View

The Great Red Spot is entirely missing; hunting around Stellarium shows me a transit about 4.5 hours before 07:00Z, which as far as I know is completely wrong. Stellarium does show the transit of Europa, but seems to have scale or timing off a little; Europa is shown already past Jupiter entirely. And it doesn’t simulate the shadow. This discussion also notes the discrepancy, and one poster theorizes it has to do with the speed of light. That’s what tipped me off to think about speed of light. Stellarium has an option to turn on light speed simulation, when I turn it on Europa looks more like in the right place. Why would I ever want to turn that off in an Earth-based planetarium simulator?

NASA/JPL Solar System Simulator

space.jpl.nasa.gov

This image has a lot in common with the Stellarium image. Again the GRS is entirely missing, although I did verify their simulator will show it at different times. Europa is also a bit further past the disc of Jupiter than I’d expect to see, presumably the speed of light issue. No shadow. This tool is aimed at showing you JPL spacecraft, so I guess I shouldn’t be surprised if Jupiter isn’t shown correctly. But they do call it a “solar system simulator” and it seems odd they wouldn’t do a speed of light correction. Here’s a link to the exact image I generated.

Sky Safari+

Sky Safari+

My new favorite iOS app shows exactly what I’d expect to see. GRS in place, the shadow, the moon still inside Jupiter’s disc. I hope this is what I see if I go out tonight.

JupiterMoons

JupiterMoons

Sky & Telescope’s iOS app also shows about what I’d expect to see. Even the shadow. No surprise this is so like Sky Safari+: I believe it’s the same developer.

Starry Night

Starry Night

An old version of Starry Night special edition. The Red Spot is in the wrong place, although it’s close. Europa and shadow look about right. I’ve only spent two minutes with Starry Night, don’t know it yet, need to tinker more.

Old friends

Not a great night last night, lots of humidity, but clear enough to drag out the scope. To look, once again, at the things I keep looking at.

Screen Shot 2012-12-27 at 6.50.45 AM

I like Jupiter. It’s so easy to find and so rewarding. Last night was fun because three of the moons all nicely bunched up to make a harmonious little set. It felt like Jupiter was being followed by three little dogs yapping at his heels, with a fourth scurrying long behind. I’m beginning to see how the personification in ancient mythology and starlore happened. I was also distracted by a bunch of little other specs of light that I thought might be other moons. No, just random magnitude 10 stars. Too bad.

Screen Shot 2012-12-27 at 7.09.36 AMI also saw the same black dot I saw two nights ago. Right in the middle of the planet, maybe a tiny bit south of the equator, and originally a bit to the west of the center of the disc and then turning with Jupiter to be at the exact middle when I last looked around 8pm. That was 49 hours after the last time I saw this black dot, or about 4.95 rotations of the planet, so I think it’s a real feature and not just an anomaly. It looks like a tiny little point spec to me, like a dead pixel on a monitor, very black and high contrast to the rest of the planet. Not like the subtle cloud features I see in images. It’s too close to the equator to be related to the 2009 impact site. I suppose it could have been this blackish smudge in the picture here from Stellarium, the position is about the same, but my spot seemed so much more discrete. I wish I had some way to capture what I saw. I’m a terrible sketch artist.

Could it be the great red spot? The two times I saw this thing were about 2012-12-25 03:00Z and 2012-12-27 04:00Z. This chart tells me I’m about three hours too late both nights. So no.

After Jupiter I tried to find the Andromeda Galaxy and failed. I need some proper star charts. I tried spotting it off of Pegasus / Andromeda, also using Cassiopeia as a sort of pointer guide. I managed to find Alpheratz (2.0), delta Andromeda (3.3), beta Andromeda / Mirach (2.1) and the fainter mu Andromeda (3.9). beta → mu → Andromeda Galaxy should have worked out, but I couldn’t make it out. The sky was so bright from the moon it was tough to see even the magnitude three stars.

So then back to Orion and the Nebula for another quick reward. I can find it pretty fast now. I focussed on the Trapezium this time and pleased myself by spotting a fifth star in the asterism, the 10.3 magnitude one to the north (Trapezium E, I think). I couldn’t make out the sixth brightest star (Trapezium F), the 10.2 one to the south just next to the brighter star. It’s funny, I can’t find a good image of what the Trapezium looks like to me in the scope; all the pictures have lots of light from the nebula, a big garish mess, whereas what I see is points of light with just a faint grey wisp of nebula.

I’m doing well with my new equipment. I don’t like the Barlow much; it’s a pain to put on and seems to degrade the image quality some. I’m more at ease with the 7.5mm eyepiece, 160x or about 3.3x the magnification of my 25mm eyepiece. Swapping those two is easy enough. Also tried out the blue filter on Jupiter. Didn’t really do much for me, just made everything unappealingly blue but didn’t help me see more detail in the clouds.

Now I want to buy more! A proper 7×50 finder scope would be nice, this red dot reflex thing is not terrific. And those wide angle eyepieces like Naglers sound terrific. But at $500 it’s about what I’ve spent on the rest of the gear combined, and I keep telling myself I should give it a few months before spending lots of money.