Sunday, January 06, 2013


Those Crazy Computers Part II

Last time we talked computers, muchachos, we got you fixed up with a brand spanking new astro-puter. You’ve probably even got some astronomy software to run on that new laptop or netbook. If’n you don’t, have a look at those old standbys, Cartes du Ciel and Stellarium. I did in-depth set up articles on ‘em here and here. Anyhoo, I assume you have some kind of a program up and running, and that you now want to do something with it.

What kind of something? Well, you can turn off the lights and admire the pretty display of your planetarium soft like I did with Skyglobe 3.6 back in ’93. Or you can print out charts to carry with you on your next Observing run, which is what I used to do in the mid 1990s with Deep Space 3D. I assume, though, that what you really, really want to do is send your telescope on go-tos from the laptop.

If that is what you want to do, you will require two additional items beyond your software (and a go-to capable scope/mount, natch), a serial cable and a USB – serial converter. Occasionally, “serial cable” means just that, a straight-through off the shelf serial cable from a computer store. If you are running EQMOD to a SynScan mount without the aid of its hand control, that is exactly what you need. Everybody else will require a special cable, which is almost always one with a DB-9 connector on one end and an RJ (“telephone” style) plug on the other.

Since the telescope makers have not seen fit to standardize, you will need a serial cable designed specifically for your scope. If you have a Meade, a Meade cable; if you have a Celestron, a Celestron cable. Some other manufacturers use the same connector layout as Meade or Celestron, but most have their own particular setups. Do not plug a cable into your telescope unless it is designed to work with your particular model. Serial cables have the potential for carrying voltage, and you don’t want to fry anything by plugging the wrong cord into your beloved scope.

Where do you plug into on the scope side? Meade and Celestron/Synta usually have the serial port on base of the hand control. Some Meades, especially older ones, may have a DB-9 jack on the scope, but the standard Autostar (497) has the serial port on the HC. Other brands? Some also have the connector on the HC, others have one on the mount. In other words, “It depends; READ THE MANUAL!” Oh, if you have a Celestron telescope there may be a connector labeled “PC Port.” Counter-intuitively, this is NOT where you plug in a normal serial cable. One bit of advice? Buy a cable longer than what you think you will need. I like the coiled ones from

The telescope end is plugged in, but where does the other end, the DB-9 end, go?” With today’s computers, there is nowhere for it to go. Serial ports on PCs are now rarer than hen’s teeth, since we amateurs are some of the very few people who still use RS-232C. Serial is very convenient for astronomy, since it allows long runs of cable, but you have to have a serial port on the computer to use it. Luckily, that is easy enough to provide with a little cable/adapter that plugs into a USB port on the computer and has a female DB-9 connector on its other end for the serial cable.

While a USB - serial cable looks like nothing more than a cable, it is more than that. It has active electronics in it and requires a device driver to be loaded into the PC. In most cases, that’s easy enough to do. With modern iterations of Windows, you plug the thing in and a driver for your USB-serial device is automatically installed. I believe the story is the same with the Macintosh.

Any gotchas? Not really. There are a lot of Chinese-made "copies" of the Prolific chip set these adapters commonly use, and those clones will usually not work with standard Windows drivers. But the Chinese manufacturers furnish compatible drivers; it's just a little more trouble to get 'em loaded. Most of the time USB - serial converters of any pedigree work without causing any heartburn. The only hang-up is that often a new user is not sure which com port the USB - serial device establishes itself as. Com 1? Com 2? Com 3? What? You will have to know the com port number to set up an astronomy program.

That’s easy enough to find out. In Windows, bring up “Control Panel,” “Printers and Other Hardware,” “System,” and “Device Manager” to see what the com port assignment is (this may vary a bit depending on your flavor of windows). I assume something similar is possible with the Macintosh, but you Apple troops know way more about that than I do. One catch: if you plug the USB - serial converter into a different USB port the next time you use it, it may be assigned a different com port number.

While not as common as they used to be, it’s still fairly easy to find USB-serial converters at BestBuy and similar joints. Which one should you get? If all you are doing is sending your scope on go-tos, almost any USB - serial cable will work. If you plan fancier things like using NexRemote or EQMOD, not just any USB-serial widget will do. What will work with those two programs and almost anything else is Keyspan’s USB-serial converter. I have a couple I bought from my usual photographic go to guys, B&H Photo.

For almost all mounts and telescopes, that’s all there is to it. The exception is the few rigs that eschew an RS-232 connection in favor of Ethernet. The only two mounts I know of that go that route are the Vixen Star Book GEMs, which only offer Ethernet coms, and the new Losmandy Gemini II computer system, which offers Ethernet as an alternative. Setting up Ethernet communications is a little more involved than serial, but not much, especially if you are used to fracking around with your home network to get your computer and printers and routers playing together. See the manual, natch.

You’re hooked up, but that is only half the battle. Then comes driver installation. Connecting to a telescope is much like hooking a printer to the computer. The PC has to know what it is talking to and how to talk to it. That is accomplished by installing a printer driver on the computer. Same thing with telescope mounts; you install a driver.

Where it gets a little different, or where it used to get a little different, anyways, is the way the drivers work. The manufacturers of printers and cameras and scanners and other common devices write drivers that are recognized by the Operating System. All programs can use a particular driver to print, scan, or whatever they want to do.

For a long time, that was not the case with astronomy programs. Until fairly recently it was unusual to have a scope maker release a driver. Wouldn’t matter much if they had, anyway. The way things evolved, each astro-program:  TheSky, Megastar, whatever needed its own special type of driver written especially for it. It was the authors of programs who were doing the drivers, and their drivers only worked with their programs. These programs use what’s come to be called “built-in drivers.”

That is still the case with some older software like Megastar, and even some of the newest and most up-to-date programs, like TheSky X. Which is not necessarily a bad thing. You can be pretty sure the driver and the scope it is talking to will work very well with the software. The catch comes if you have a new or uncommon model of telescope mount. You will be dependent on a program’s author to provide a driver. With big commercial programs like TheSky, it usually doesn’t take long for the software maker to release a driver. With older programs, especially those that are not well supported, like Megastar, you may never get a driver.

Assuming a built-in-driver program supports your telescope mount, what do you have to do to get it going? Not much, usually. Most often, all you have to do is select your telescope model from a telescope set up window, enter the proper com port number, and leave the defaults as they are. The driver will know all about the things like location, time, time-zone and other settings you have entered into the program.
Back in the late 1997, a dude named Bob Denny had a better idea. Why shouldn’t scope drivers be like printer drivers? Why not develop a driver system for astronomy? One that would allow a single telescope (or focuser, or CCD camera, or dome control) driver to be used by any astronomy program. Thus was born ASCOM, the “Astronomy Common Object Model.”

It took a while for Bob’s system to catch on. At first it seemed odd to us that you would have to download and install a (free) program to make your scope talk to your computer, but in just a few years we all got over that and ASCOM became the dominant means of communicating with telescopes. Even programs that formally eschew ASCOM like TheSky can be configured to work with it. The advantages? Since it’s an “open” system, anyone can write a driver for it, and that means that somebody, whether the seller of the mount or Joe or Jane Amateur Astronomer, writes a driver for a new mount almost as soon as it is released. No waiting for software manufacturers’ updates.

So, what do you have to do to make all this goodness work for you? There really ain’t a lot to it. You download the ASCOM “platform” and install it on your machine to start. You will also want to download and install the drivers for the mounts or other devices you use. All that is simple; just download the files, telling Windows you want to open rather than save them, and click through the install dialogs saying yes to everything.

How do you get it working? That will depend to some extent on the program you plan to use with ASCOM. Start up your planetarium (or whatever sort of ASCOM compatible astro-ware you intend to use). There will be an icon or menu selection along the lines of “Connect to ASCOM" or "Connect to Telescope.” Mash it, and you will be confronted by the window shown here.

What do you need to fill in? Latitude and longitude if ASCOM has not already retrieved it from your planetarium program. Normally that should be the same as the planetarium program's current "site." That done, choose your basic scope type, "Celestron" for example by pushing the window's "Select button."
When you have the driver type entered, hit the "configure" button and you will be taken to the Celestron (or whatever) driver setup window, where you will specify a particular scope model, whether it is tracking in EQ or alt-az mode, and what the com port (assigned to the USB  – serial cable) is. You'll see some additional fields for things like aperture, central obstruction, etc., but you can leave those blank. The Lat/lon blanks should already be filled in. If not put your site's position in them. "OK" the setup window and you should be ready to roll.

Back on the Driver Selection window (which should still be onscreen) push the Connect button, the red box should turn green, meaning the telescope is connected to the computer and software. If it won't connect, recheck all the steps and be sure the telescope is turned on and—Uncle Rod often forgets to turn on the pea-picking telescope.

Once ASCOM is configured, you don’t have to worry about it much anymore. When you come back next time, you shouldn't have to change anything if you are using the same telescope; just click the Connect icon or menu item, mash “connect” on the ASCOM dialog window, and off you go again.

Now that you are connected, how you actually send the telescope to objects depends on the particular program. With a planetarium, you’ll usually select an object onscreen and either click “slew to object” on a right-click menu you can summon, or mash a “slew to” icon on a toolbar.

One common question I get? “Can I use ASCOM with more than one program at a time? I need to control my scope, my dome, and my auto - guide camera.” You can, and it is usually fairly simple. Some scope control drivers like EQMOD (for the Atlas EQ-6/Sirius HEQ-5) work as “hubs,” allowing multiple device drivers to connect through them. Otherwise, you can load POTH, an ASCOM component that looks like a driver but acts as a hub allowing you to connect to multiple drivers. There are clear instructions for using POTH on the ASCOM site.

Is there a drawback to ASCOM? It’s not popular with a few software developers, but based on my experience with it stretching back over a decade, the only real problem is that ASCOM is Windows only. There has been talk about porting ASCOM to the Macintosh’s OSX operating system over the years, but it has never happened. Maybe because in the past the Mac was not popular enough with amateurs to warrant it. Now that there is much more astro-ware available for the Apple, I’m hoping we will finally see that—and maybe an ASCOM version for the iPhone/Pod/Pad, too. There is no ASCOM for Linux, either. I believe there is a similar driver system, but I don’t know pea-turkey about it.

You’ve got the software and hardware squared away; now you can get going in the field. How do you do that? What you do not do, contrary to what some astro-PC novices think, is turn on the telescope/mount and PC and start playing with the computer. To many newbies it seems obvious that you will align the scope for go-tos using the computer. Uh-uh. Nosir buddy. With the exception of some special software we’ll discuss below, you align the old-fashioned way.

Once you’ve got it cabled to the mount, leave the computer alone. Oh, you can power it up, but DO NOT attempt to connect the astronomy program to the telescope. Instead, fire up the mount and do a standard go-to alignment with the hand control. Once you are completely done with that, then boot the astroware and connect to the scope with ASCOM or the program’s built in driver.

Some very recent astronomy software, mostly apps for iPhones/Pods/Pads, can go-to align the telescope. An example is Celestron’s SkyQ application. Used in conjunction with their new SkyQ Link wireless rig for scope control, you can supposedly (I have not been able to try the Link widget yet) align the Celestrons without a hand control.

After aligning and connecting the software to the telescope, it’s just a matter of knowing the astronomy program:  how you send the telescope on go-tos and how you sync. Sync? What’s they-at? Sometimes you will find that when you go-to a target and center it up with the hand control, it is no longer centered under the target cursor on the PC screen. How do you fix that? With the computer program’s sync, which is different from doing a sync with the telescope’s hand control.

Computer sync makes the telescope computer and the PC computer agree that a target is centered. Say you send the scope on a go-to from the computer. When the scope stops, the target is not quite in the middle of the eyepiece. You center it using the hand control. But then it's "off" in the astronomy program. Time to sync.
Which is easy. After you go-to a target, hit the sync menu item or icon in the astronomy program (NOT ON THE HAND CONTROL). You will be prompted to ensure the object is centered in the eyepiece. Do so, and push the (virtual) sync button. The cursor/circle/FOV indicator on the PC will move to center the target. This is useful function and is implemented in most astronomy software.

What’s the next step in PC-telescope use for some folks? Wireless connection of the laptop computer to the telescope. This used to be dicey, involving Bluetooth transmitters and receivers that were hard to get going and hard to keep going. That’s changed with the introduction of Southern Stars’ SkyFi Wi-Fi scope control system and Celestron’s above-mentioned SkyQ link. While both these devices were introduced to allow iPhones, iPads, and tablets to talk to telescopes, they will work with plain old PCs, too.

Not that I’ve tried these things. I’ve recently been tempted by SkyQ Link, since it is advertised to allow wireless operation of NexRemote, but I can’t entirely get past the “why?” In addition to the computer, I typically have a camera, a battery, and a JMI Moto Focus connected to my scope. While eliminating the computer cord would help a little with cable clutter, I’d still have a minimum of three cords connected to the SCT, so I’m not sure wireless scope control would help much. It would be cool, of course.

What is the ultimate in computer control of telescopes? Dispensing with the consarned hand control altogether and letting the computer do everything. Thus far there are only a few mounts that can do that. The most sophisticated of these are the two German equatorial mounts sold by Software Bisque, the ME and the MX. They do indeed do everything with a PC (running TheSky). In fact, they can’t do anything without a PC. Both are fine mounts, but the ME and even the less expensive MX are far more capable and complex and costly than what most of us, and especially your stingy ol' Unk, want or need.

There are two programs for the rest of us that do allow scope control without an HC, NexRemote and EQMOD. While they are different in origin, with NexRemote being provided by Celestron/Synta and EQMOD being a free open-source project, they are very similar. The primary difference being that NexRemote works with Synta’s Celestron-branded telescopes and mounts, and EQMOD with Synta’s SynScan mounts (the Atlas/EQ-6/AZ-EQ-6, the Sirius/HEQ-5, etc.).

For a full rundown on these wonderful programs, investigate the links above, but what both do is add more features (including GPS for GPSless mounts), allow everything to be done from the PC without the hand control even being plugged into the mount, and, maybe coolest of all, allow the use of a wireless PC gamepad (or even a Wii remote) in lieu of the telescope hand control. I like both systems very much, especially when I am imaging. NexRemote and EQMOD allow me to sit at the computer and run everything instead of having to continually get up and go to the scope, or at least hunt around for a cotton-picking hand control.

Is this PC junk for everybody? Nope. Give it a try and you may like it. Or you may not like it. Even astro-ware-a-holic Unk occasionally get tired of all the stuff, and goes back to the hand control. Sometimes I even leave the laptop at home and enjoy my quiet Dobsonian, Old Betsy, aided only by a set of Sky Commander digital setting circles. But there is no denying computers hooked to telescopes have increased our capabilities. With the PC running SkyTools 3, I am at my most efficient, clicking from one object to the next. That is, along with the Mallincam, what has allowed me to do 100 or 200 Herschel objects in one night.

So astronomy computing is a good thing, and PC telescope connectivity is also a good thing. Yeah, sometimes I get weary of toting all the gear, but I get more done with a PC on the observing table and a cable hooking PC to scope. All I can say, muchachos, is we have come a long way since SkyGlobe 3.6.


Brilliant edition,

thanks 'unk!!


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