Sunday, January 31, 2016


Simple. Neat. Really No Trouble at All: Stellarium

Do you like pretty planetarium programs? Computer programs that put a beautiful depiction of the night sky on your PC's display? I know I do. Sure, a planetarium doesn’t have to be pretty to be useful. Heck, I did a lot with good, old Sky Travel, and even in the 8-bit Commodore-64 days it was hardly cutting edge as far as graphics.  But pretty is nice. Pretty and useful is even better. And pretty and cheap is best of all as far as I am concerned.

As I wrote the other day, when it comes to astronomy software, planetarium programs anyway, what I’ve used most in recent years is that oldie-but-goodie TheSky 6 Professional from Software Bisque. It’s a great soft that does everything except brew the coffee at dawn when your observing run is done. There is only one problem with it:  it’s getting old. It has long since been obsoleted by Bisque’s current TheSky, TheSky X.

In most respects, TheSky 6’s obsolescence doesn’t make much difference. Bisque worked hard to add features and squash bugs over the lifetime of the program, so it is pretty bulletproof, does many things, and does most of those many things well. In only one respect does the fact that it is no longer supported cause a problem. I found out what that was the other day when, in a sanguine mood, I decided I’d take a picture of the little morning comet, Catalina.

In order to do that I needed software with current orbital elements for Catalina. With that, I could easily figure out when I should start my astrographic run and when I’d have to end it ahead of the Sun. The program would also allow me to center the telescope on the comet quickly and easily, with just a mouse-click or two. "Well, I’ll just fetch the current orbital elements for Catalina with TheSky 6 and—oh…wait…  Rut-roh."

While I could look up the orbital elements of the visitor and enter them manually into TheSky (if I could figure out where and how to do that), I was not going to be able to have the program automatically download them. Something changed with the URLTheSky uses for retrieving orbital elements for comets and asteroids, and asking the program to do that now results in an error message.

Hmm... So, I could try to get the elements into TheSky manually, or I could just take the quick and easy way out and use another program. My normal choice would have been that old favorite Cartes du Ciel. Unfortunately, as I mentioned last time, it errors-out and crashes on my Toshiba laptop of late. I’d tried various fixes, but nothing had worked, and I wasn’t in the mood to fool with it anymore.

What would I do, then? What would I do? Unfortunately, TheSky and CdC were the only full-featured planetariums currently on my hard drive. I’d have to pick something else. I could have shelled out more than a few bucks to Bisque for TheSky X, which is available for immediate download from their website, but I am cheap, and I was also leery of trying to learn to use X in one afternoon. Then I remembered Stellarium.

Stellarium was program I’d used occasionally over the years, and I’d heard it had been improved greatly since I’d last looked at it, that some of the missing features I wanted were now present, and that more than a few of the rough edges I hadn’t like had been rounded off. Since I didn’t have any other ideas, and Stellarium is free, I figured I had nothing to lose, and downloaded and installed Stellarium 0.14.2.

The program is available for Linux and OSX as well as Windows,  but what I downloaded and what I’ll be talking about here exclusively is the Win version (which requires Open GL graphics), since I wanted to use the PC-only ASCOM telescope drivers with it. Don't have Windows? As I outline below, Stellarium has some built-in scope drivers, so you may be OK.

One thing’s sure:  Stellarium is a pretty program despite its freeware status. Its authors have always endeavored to make their sky look as attractive and realistic as possible, and as soon as I ran the new one, it was obvious that they haven’t stood still in that regard. Stellarium is more striking than ever, from the beautifully hued and toned sky to the lovely horizon landscape. It’s a trip to see the lights of the farmhouse to the northwest come on as darkness falls with the Guéreins horizon landscape selected.

"Pretty" is absolutely worthless if it impacts the usability of a planetarium, however. A little playing around proved that that hasn’t happened with Stellarium. 0.14.2 was just as spritely as ever on my mid-range Toshiba laptop. Grabbing the sky to move it around was as smooth and satisfying as it was many versions ago despite all the additions and improvements to the graphics.

Looked good, yeah, but that wasn’t really what I was concerned about this particular afternoon. My goal was downloading the elements for Catalina, getting the hairy star on my screen, and, first of all, determining when it would be well placed for imaging.

All I had to do to get the current orbital elements into Stellarium was open the configuration window and select “plugins” and “solar system editor.” There I found a button labeled “get orbital elements.” I specified comet elements, and was done. A search then turned up Catalina right where it was supposed to be adjacent to the Dipper’s handle in Ursa Major—I checked an online finder chart to make sure the program had the comet plotted correctly. Well, heck. That was easy enough.

A sixty-four dollar question remained, however: As much as I liked Stellarium in the house, would I like it out under the stars connected to a goto telescope? I thought I’d find out. But to do that I’d have to set it up for telescope control.

There are two methods of  connecting the program to a computerized telescope. Easiest, perhaps, is using Stellarium’s built-in scope drivers.  If you have a Meade or Celestron or telescope or a few others that are compatible with those “standards,” the built-in drivers are OK. For details on using them, see my article on Stellarium from five years ago.

But what if your telescope isn’t one supported by the built in drivers? Or you just don’t want to use them for some reason? What if, like me, you want to use the ASCOM universal telescope driver system? StellariumScope has you covered. This add-on makes Stellarium ASCOM compatible just like Cartes du Ciel or any number of other planetariums. That means Stellarium can control almost any telescope mount under the Sun.

Making ASCOM work with Stellarium is fairly easy. You must first download StellariumScope (make sure you get version 2015.12.2.327, which may still be listed as a “beta”) and, if you don’t already have it installed on your computer, the latest ASCOM “platform,” the software that runs ASCOM drivers. Of course you will also want to download (from the ASCOM site, usually) the driver for your particular scope/mount. While the authors of StellariumScope say on their website that their utility was expressly designed to allow Stellarium to work with the EQMOD ASCOM driver, they also say it should work with almost any other scope for which an ASCOM driver is available. I’d be surprised if any run-of-the-mill ASCOM driver gave StellariumScope problems, since EQMOD is far more complex than most.

Once you’ve installed StellariumScope and ASCOM (I’m assuming you’ve got the latest version of Stellarium on your machine), start Stellarium and go to the telescope control configuration section in the plug-ins window, just as described in my earlier article. The only diff is that you choose “External Software or a Remote Computer” rather than specifying that you have a Meade or a Celestron or whatever. That done, close Stellarium.

The first time you run StellariumScope, you will likely be dismayed when it presents you with a bunch of configuration errors. Don’t worry; this is normal and it will tell you how to proceed, giving you instructions for modifying Stellarium’s configuration (usually automatically through StellariumScope). That done, you can set up StellariumScope’s defaults, such as its colors, and whether or not it should automatically start Stellarium when it executes (yes).

Eyepiece view...
The final step is configuring your ASCOM driver. Do that from the main StellariumScope window, by clicking “select mount,” choosing the appropriate telescope driver, and then entering all the required information in ASCOM’s “properties” window. Same old stuff:  com port, lat/lon, tracking mode, etc. That is all there is to it. With the telescope goto aligned and powered up and its serial cable connected to the computer, you can now tick the connect box on the StellariumScope window.

If all is well, Stellarium will connect to your mount (if, like me, you’ve got ASCOM’s little hand control enabled, it should appear). If you move the screen to the object the telescope is currently pointed to, you should see a reticle cursor centered on that object. If you have problems, the help file included with StellariumScope is clear and well-written and should get you out of your mess.

I got StellariumScope working with minimal difficulty, only scratching my head and backtracking once or twice. But just because it was working, that didn’t mean I’d like the way it worked. With Hermione, my 5-inch refractor, on the CGEM and the CGEM aligned and ready to go, I thought I’d give Stellarium its chance to shine.

Frankly, it was all rather anti-climactic. I connected to the mount with StellariumScope, clicked on the magnifying glass in Stellarium’s left icon-bar, searched for the Pacman Nebula, centered it when it was found, held down CTRL and pressed the "1" key, and the CGEM went there, centering the nebula in the frame of my DSLR without a hitch. The only other commands you’ll normally have to mess with are CTRL and 3 (sync) and CTRL and 5 (stop slew). If you don’t like using the CTRL key with a number key, StellariumScope will let you use other keys and  combinations. That’s all there is to it; no fuss no muss. While that is the go-to telescope control story, however, that’s hardly all there is to the new Stellarium.

The Stellarium display is, yes, awful pretty, but what’s even more important is what’s in it. Stellarium is endowed with a useable set of deep sky objects and that set looks to be growing. While it has had the entire NGC/IC for a while, the authors have mentioned recently that the program's deep sky catalogs have been expanded. Unfortunately they haven’t specified in exactly what way. While the DSO screen in the “sky and viewing options” window now allows you to select the PGC and other “beyond the NGC” catalogs, not all of them work. Ticking the PGC box and a couple of other didn’t do a thing, though selecting “LDN” did make dark nebulae appear. I am assuming that the PGC and some of the others are works in progress. At least you don’t have to worry about stars; stars down to magnitude 18 have been available for a while (you download the expanded star catalog with a utility included in the program's configuration section).

DSLR image sensor frame...
What else is new? One thing I don’t remember from years ago is a utility on the bottom icon bar to let you measure distances and position angles between objects. Just click the angle icon, click a starting place on the screen, and, holding down the mouse's left-button, pull out your measuring stick. Worked elegantly and was a big help when I was writing a recent observing article for Sky & Telescope.

While the ability to place objects in eyepiece fields has been around for a while, it’s been improved. You can now add eyepieces with an icon on the top right of the screen without having to mess with the left-side icon bar. When you’ve got all your eyepieces (and telescopes) programmed in, select an object, choose an eyepiece and telescope combo, and you get a great looking eyepiece field view. This top right icon-menu is also where you can set up camera sensor frames for display on the normal chart, allowing you to easily compose your shots. In addition to placing a frame around your object appropriate for your scope/camera, you can easily rotate that frame.

There are quite a few other additions, too, and not just the fairly recent inclusion of comets and asteroids. It’s now easy to find planetary positions with the AstroCalc module. Want to know the when/where/what of upcoming meteor showers? You can now engage a search dialog that will find them for you, give you zenith hourly rates, and find and display the radiant. Mostly, however, Stellarium is much the same as it was when I talked about it five years ago: pretty and good. Well, almost the same; there is one difference. I opined back then that it could not replace Cartes or other “serious” planetariums. That’s not so true anymore. It’s still pretty, but it’s much more capable than it used to be.

After one evening of using Stellarium, I put my credit card back in my wallet. I had been prepared to pay for TheSky X Professional, but suddenly decided I didn’t have to. That is not to say that TheSky X isn’t fantastic or that it doesn’t do a lot more than Stellarium. It just says that for little old me Stellarium is more than enough. It does everything I need a planetarium program to do and then some. And it is continuing to advance. I understand the next release will feature not just a pretty sky background but a photo-realistic one. I can hardly wait.

Oh…how did the comet turn out? It didn’t. Not that night, anyway (I did finally get a snapshot of Catalina a week and a half later). Stellarium could definitely have pointed my scope at the visitor, I was sure…but. By one a.m. clouds were not unexpectedly moving in, and even if they hadn’t been, by that late (for me) hour, my eyes were growing heavy. I did get a nice image of the Pacman Nebula, though, and had found a new astronomy program that I think is going to be my go-to planetarium for a while.

I like Stellarium too. I stuck with TheSky 6 as long as I could -- still run it occasionally -- and have TheSky X but have found its UI confusing. Stellarium seems to do what both of them do, better, and the price is right!
I have (or rather, had) TheSky6 and was going to purchase TheSkyX. However, TheSkyX is now subscription software; i.e., after the first year you have to pay for updates each year. Bug in the program? After a year of ownership it won’t be fixed on your copy if you don’t pony up the cost of the update which is approximately 20% of the original cost of the program. No thank you. Instead, I purchased Starry Night 7. After reading Rod’s blog I wish I had also taken a look at Stellarium. I too am cheap (oops - make that frugal).
No trouble, not sure. There are some driver incompatibility and ressource issues when using a fast graphic card (eg. GTX 770) forcing the PC to reboot.
Also, if you try to simulate the sky up to the limit magnitude (Mv 21) looking for Sedna for example, the db displays well Sedna but no stars of mag 21...
Otherwise, indeed there is no problem.
Hi Uncle. Thanks for the review. Great! One question: Is the computer connected to the mount with a EQDIR cable? Thanks
I have used an EQDIR cable with my Atlas EQ-6, but this is a Celestron CGEM and can't use a standard Celestron serial cable.
Thanks. I will try with the EQDIR cabre this coming weekend.
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