Sunday, July 13, 2014
Ah, yes, the lazy, crazy, hazy days of summer. With an emphasis on “hazy,” muchachos. My intent for a while—well, for two solid months—has been to get the cute little Mallincam EX out and see what it will do. I have almost done that a time or three, but the cloudy, milky skies of Gulf Coast midsummer nights have dissuaded me.
Based on my limited experience with the camera at the Deep South Regional Star Gaze Spring Scrimmage, I believe Rock Mallin’s amazingly cheap deep sky video cam has real possibilities. B-U-T…I want to give it a fair chance to show what it can do under clear if not necessarily dark skies.
A couple of recent evenings were supposed to be clear if not overly transparent, but those forecasts did not prove correct in the least. Even if late afternoon thunderstorms didn't move in, clouds and mucho haze did. Conditions have simply not been good enough for deep sky imaging of any sort.
But I wanted to get outside and play telescopes anyway, and what I saw out at the dark site last week gave me an idea. As you’ll recall, my mission on the Possum Swamp Astronomical Society observing field last week was to get my good, old Denkmeier Standard binoviewers going with the Edge 800 C8 and my VX mount. The binoviewer had nothing to do with Unk’s latest brainstorm (if you want to call it that), however.
Most of my time last Saturday was taken up by getting the C8’s, Mrs. Emma Peel’s, VX mount goto aligned when it was hard to see alignment stars due to passing clouds—or maybe that oughta be “passing sucker holes.” When I finally got the mount going, I focused on making the binoviewer work with the new scope and my old eyes. Nevertheless, I was somewhat aware one of my fellow club members, Taras, who’d set up his 15-inch homebrew Dobbie next to me, was trying something new with his Sky Commanders.
He, like many of us latter day Dobsonian users—yes, your SCT-happy old Uncle wields a Dobbie regularly—uses digital setting circles with his telescope. You know, “push to.” Digital setting circles have been with amateur astronomy for over a quarter century. In the beginning, that is all they were, digital setting circles, readouts that showed the right ascension and declination of your telescope.
The first wave digital setting circles weren't much more accurate—if any more accurate—than the analog setting circles on an orange tube C8. All they did was give you a readout in nice, big L.E.D.s that freed you from squinting at analog circles with a red light and a magnifying glass.
Then, as the 1980s ran out, “DSCs,” as us acronym-happy amateur astronomers began to call ‘em, started to change, to advance. In the hands of folks like a little California company called “Tangent Instruments,” who were making a name for themselves in telescope electronics (for companies like Celestron, Jim’s Mobile, and others) DSCs were becoming real computers.
The first benefit of the transition from readouts to computers was that the need for polar alignment became less exacting. The first DSCs were, again, just digital readouts, so, like analog circles, their accuracy was highly dependent on how closely the telescope mount was aligned to the celestial pole. The next generation of digital setting circles made that far less critical. By having the user “align” on one or two stars, the computer could figure out a polar alignment offset and yield decent push-to accuracy without a freaking drift alignment.
“What the hail is this ‘push-to’ you keep going on about, Unk?” If you are a newbie, you may be confused about the difference between goto and DSCs. Both goto mounts and DSCs require you to align on one or two stars, to center those stars in an eyepiece. It’s when you are aligned that things get different.
With a goto mount, you punch the number of the object you want to view into the hand control, push a button, and motors move the scope to that location. You enter your desired object into a DSC in similar fashion. There are (usually) no motors involved with digital setting circles, however. Instead, the DSC computer will indicate which way the scope needs to move in RA/Dec or altitude/azimuth to reach the target. You then PUSH the scope TO the object, watching the numbers on the DSC display decrease to zero as you approach it.
Did you notice the “alt-azimuth” above? That was the next big step up for DSCs after the polar alignment conundrum was solved. When DSCs were first catching on in a big way, in the late 80s, Dobsonian telescopes were also big (in popularity as well as aperture). Maybe as popular as they ever would be. Naturally, Dob owners, some of ‘em, wanted DSCs too, and it wasn’t long before all the names in the business, JMI, Lumicon, Roger Tuthill, and more (most of whom used Tangent’s electronic guts) were offering rigs that worked as well with alt-azimuth Dobsonian Mounts as they did with equatorials.
Just one more piece and the DSC puzzle would be complete. Even after adding computer horsepower, DSCs were awkward to use. First, you had to look up the coordinates of your object in a fraking book. Then you had to move the scope until the R.A. and declination numbers on the display matched those of your target. Sounds easy, but ‘tain’t always so. As you move to the northern (or southern) area of the sky, them numbers begin changing awful fast on the readout, making it difficult to home in on ground zero.
Afore long, DSCs had object libraries. Want to look at M51? Punch up M51 on the computer and the DSCs would indicate the direction and distance you needed to push your scope to get to the target. DSC object libraries started out with a measly 110 (Messier) objects, but as the 90s came in and computer chips got cheaper, the top of the line rigs were soon sporting the entire NGC and IC catalogs.
So, DSC owners lived happily ever after? Not quite. As goto scopes, the Compustars and the LX200s, and, soon, the NexStars and LX200 GPSes, hit the street, push-to users began to feel a mite left out. Not only did the top tier goto rigs have hand controllers that contained many more objects than any digital setting circles computer, it was far easier to enter those objects into a goto HC.
Whether you own an ancient Tuthill rig or the latest Argo Navis or Sky Commander, one thing has remained constant: DSC computers make do with just a few buttons to perform many tasks. Almost all goto hand controllers have numeric keypads, but, as far as I know, no DSC computer does, not even the powerful Argo Navis. You wanna enter an NGC number? You do that with up and down and left and right cursor button pushes or, at best, by twirling a dial.
It would also be nice if DSC libraries contained more objects. While the mighty Argo Navis has 29,000 DSOs in its library, that number pales in comparison to the 145,000 the Meade Autostar II hand control boasts. The other players? Most are still stuck at the NGC/IC-and-a-few-more-catalogs level. Hell, if I want to look at PGC 15435, I wanna look at PGC 15435.
Luckily, there is a relatively easy way to make digital setting circle computers easier to use and more full-featured. Almost from the beginning, DSCs have featured RS-232 serial ports that allow them to be interfaced to a PC. Why would you want to do that? Connected to a computer, you could select objects by clicking on them with a mouse, and you’d have the huge object library of the average PC (or Mac) astronomy program available for your DSCs.
Alas, the first time I saw a DSC hooked to a laptop, at the 1997 Texas Star Party, your old Uncle was not impressed. I had the good fortune to be set up next to a friendly dude with a 30-inch scope. Well, it would have been fortunate if we’d had much in the way of clear skies. We did get a few so-so nights during the week-long star party, however, and I was able to see how my new friend’s push-to rig, a JMI NGC Max and a laptop running TheSky planetarium software, worked.
In a way, it did fulfill some of the promise Unk thought inherent in the combination. When Mr. Man wanted to go to an object, he clicked on it on TheSky’s screen. That object could be any one of the many deep sky wonders in the program’s large library. That was the good. The bad was the way you had to push to your object. What you did was move the scope while watching a crosshair cursor on the program’s sky display.
There was a problem inherent in that. You had to have the computer close enough to the scope so you could watch the display as you pushed. If you were moving the scope to a radically different position in the sky, you’d probably have to move the computer, too. For best results, you really needed to mount the computer on the scope somehow.
That was something that didn’t seem overly practical to Unk. Oh, maybe if you were running a 30-inch Dob it might be OK, but my old Toshiba Satellite, which weighed dern near 20-pounds, would have thrown my Dobbie of choice, Old Betsy, a 12-incher, seriously off balance, to put it mildly. I decided DSC + PC was an idea that wasn’t quite ready for prime time and thought no more about it for a long time. I wasn’t alone. While I saw lots of amateurs using digital setting circles on star party observing fields, even the folks that had laptop computers with them rarely had their computers interfaced to the DSCs.
It didn’t much matter anyway, since it took a long time for Unk to convince himself Betsy needed DSCs at all, whether computer interfaced or not. Betsy and I were perfectly happy running down objects using Sky Atlas 2000, Herald-Bobroff, a Telrad, and a 50mm finder.
We were, that is, until Unk got his first goto SCT not long after the turn of the century. It was at that time I decided I was more interested in seeing objects than hunting objects. I wasn’t getting any younger, and I wanted to see as much of the Great Out There as I could in the years of observing left to me. In other words, goto had spoiled me, and I knew that if I were to continue using Betsy I’d at least have to equip her with DSCs.
“Which DSCs?” Was purty easy to figure out. I crossed the Tangent-based units off my list. They were, in my opinion, more difficult to align accurately than they should be, and their accuracy seemed to suffer in comparison to goto scopes. That left the Argo Navis, which had the advantage of numerous features and a high-powered processor, and the Sky Commander, which offered simplicity (and a lower price, which always gets Unk’s attention). Both were easy to align— point at two stars, you were done—and both offered goto accuracy comparable to my NexStar 11 GPS. I settled on the Sky Commanders, though I can see myself driving (sailing?) an Argo someday.
The Sky Commanders have worked great for me for over seven years. In fact, their accuracy and Betsy’s still amazing reach at the 2009 Deep South Regional Star Gaze were what impelled me to undertake The Herschel Project. The Commanders just worked. They weren't feature laden, but the features they had were usable and useful. Well, ever’thing except the RS-232 serial port. I had no idea how well that worked and didn't feel moved to find out.
Oh, I knew what it was for, mind you. It had two purposes, upgrading the firmware and interfacing the DSCs to an astronomy program running on a PC. I didn't need to do the former and had little interest in the latter. Remembering the long ago night where I’d watched that cursor crawl across the display of TheSky, I thought I’d give it a pass.
Which returns us to last Saturday night on the PSAS observing field. When I finally got the mount squared away and had proved to myself that the binoviewer and StarSweeper focal reducer would work with the Edge 800, and that my old eyes could still more or less handle a binoviewer, I got curious as to what Taras was up to with SkyTools 3 and his Dobbie.
What prompted my curiosity was him hollering, “IT WORKS! IT REALLY WORKS!” Unk strode over and enquired, “Calm down, son, what works?” Taras informed me this was the first time he’d connected his laptop running SkyTools 3 (which purchase was my suggestion) to his Sky Commander (which purchase was also my suggestion). Looking at his laptop, I noted the screen was pointing away from the scope. “How the hell do you see where to move the scope if you can’t see the screen?”
Taras informed your benighted old Uncle that he’d discovered you didn't have to see the SkyTools display to know how to push your scope to a DSO (or any other object). Click on an object in the ST3 observing list, mash the on-screen “push-to” button, and the object was sent to the Sky Commander computer, which showed you how to move the scope as per usual.
He also enthused about some kind of position indicator bars, and, further, said some English lady was a-telling him when he had his selected objects in the eyepiece. Some English lady, huh? Unk moved away slowly, back to his C8, Mrs. Emma Peel, and commenced messing with the binoviewer again. I was intrigued, however. Making all one million SkyTools objects available to the Sky Commander computer sounded like something Unk might be interested in. Dang tootin'.
Next morning, but not early the next morning, I took stock. If I wanted to hook my Toshiba laptop to the Sky Commanders, I would have to have a cable. A check of the pea-picking Internet turned up a couple of astronomy dealers who would sell me a Sky Commander computer control cable for 30 bucks. Call Unk a cheapskate, but 30 smackers for a roll of wire and a little plastic DB-9 connector seemed high. So, I had a look at the computer cable that came with the Sky Commanders.
This cable, with an RJ plug on one end for the Sky Commander computer and a DB-9 adapter on the other to plug into a PC serial port, would obviously not work for controlling the Commanders with a computer. The Sky Commander end of the cable had a jumper across two pins, no doubt to put the computer in programming mode. It was also way too short to be practical for use with a scope. Would Unk have to shell out 30 bucks? He was not yet ready to resign himself to that awful fate.
Grabbed my trusty multimeter and the (decent) Sky Commander manual, and I soon determined all I should need was a telephone extension cable—a phone extension that plugs into the wall, not a handset extension. Plug one end into the Sky Commander and the other into the RJ – DB9 adapter that came with the programming cable, and I would be ready to roll.
Me and Miss D. needed to stop at the Home Depot for supplies as we continue cleaning up and clearing out the old Chaos Manor South, and I seemed to recall the home improvement bigbox sold telephone accessories. They did indeed, a few, anyway, sandwiched between cell phone geegaws. I found a 25-foot phone cord I thought would serve. Cost all of five fraking bucks, which was a dern site better than 30—if'n it worked, of course.
Last Tuesday night, we finally got some semi-clearing, and Unk decided to give the DSC-computer trope a go. Old Betsy, my time-honored 12-incher, was in fine fettle—I’d spent the day cleaning both her primary mirror and her Dob body, since she’d been exposed to a fair amount of dust in my initial clean-up of the shop. The only bad was the sky, which in typical midsummer fashion had gone from looking acceptable at sunset to nearly closed-down at dark.
Hokay, what would be would be, as Doris Day used to say. Lit a citronella candle to keep the skeeters away—I hate to use up the somewhat expensive Thermacell cartridges and pads for an informal backyard run. Set up the laptop, connected one end of my new cable to the USB serial adapter and t’other into and to the Sky Commanders’ RS-232 port. Didn't start SkyTools just yet, though. As with a goto scope, before you can use the computer, you have to do a normal alignment. If I could do a normal alignment.
I always use Polaris as my number one DSC alignment star. This time of year, I’d probably pick Regulus as number two. Problem was, both were behind consarned clouds. I waited, as I did last week, hoping for the North Star to peep out, but it soon became evident that all that was going to happen was that the sky was going to get progressively worse.
Vega was in sight, so that would have to be star one. Spica, almost due south, was also (intermittently) visible and would be my number two. I turned on the Sky Commander, entered the date (no time or location required), and centered the two stars in succession. Alrighty, then, computer time.
I launched SkyTools and selected the “RealTime” tab, which is where you do your scope interfacing and gotoing (or pushtoing). Next, I found “select/configure telescope” on the telescope control menu. All I had to do was choose “Sky Commander” and specify the baud rate I wanted to use for communications. Since, as I’d read in the Sky Commanders manual, the default in the DSCs is 9600bps, I told SkyTools “9600.”
Taras had mentioned something about SkyTools talking to him in DSC mode, so I’d enabled voice in the program preferences. Still, I dang near jumped out of my pea-picking skin when a sexy-sounding Englishwoman declared, “TELESCOPE CONNECTED!” when I clicked the “connect to telescope” choice in the scope control menu.
Before I actually tried to do anything with the Sky Commanders, I thought I’d better have a look at the “configure push-to indicators” menu I’d discovered. The only thing I did there was change mount type from EQ to alt-az. Time for the rubber meets the road thing, I reckoned.
I brought up the Messier list in RealTime, selected “M13,” and mashed the “push to” button. I was not as startled this time when “Audrey” told me to “Push telescope to target!” (SkyTools refers to its audio guide as Audrey, but I will probably just think of her as “Betsy”). At the scope, I had to mash the down cursor button to bring up the push-to indicators this first time, but that was all. I maneuvered the scope to M13 watching the Commanders’ numbers count down just as always. When Bertha/Audrey intoned “Telescope on target,” I inserted the Happy Hand Grenade, my 16mm Zhumell 100-degree eyepiece, into the JMI NGF focuser and had a peep. Nuttin’ honey.
A look up showed why: Hercules was now a mass of clouds—I couldn’t make out a single one of the constellation’s stars. The scope did seem to be pointing in the proper direction, but I wanted to be sure. What was available? The Big Dipper was shining bravely, if barely, through the thickening haze to the northwest. I loaded my SynScan alignment star observing list and selected Mizar, which is not only bright but distinctive.
Pushed “push-to” again, Bertha told me to get out to the telescope and start pushing, and that is what I did. When the indicators on The Sky Commander was zeroed out, I peered into the Zhumell. There was Mizar centered in the field. Yeehaw! My five-buck cable damn sure worked. I tried a few more bright stars—Arcturus, Spica, and one or two others—and all were in the center of the field, convincing me all was well.
Since even the bright stars were now disappearing, I pulled the Big Switch, carried Bertha back inside the shop, and went in the house to give Miss Dorothy the good news—I hadn’t let the smoke out of my DSCs. The cable and software worked perfectly; the Sky Commanders now had access to SkyTools huge database (including, importantly, asteroids and comets). And it was so much easier to click on objects on the ST3 display than to cursor to them with the Commanders’ freaking little membrane keys.
Actually, the ST3-Sky Commander goodness doesn't end there. In addition to sending objects to the Commander so you can use the normal DSC readout to push the scope to target, SkyTools displays two large, red push-to indicators; one for altitude and azimuth. Push the scope till these red bands/graphs dwindle away to nothing, and you will be on your object. You can also tell SkyTools Interactive Atlas to display a reticle showing scope position on the map, but as with my buddy’s long ago TSP rig, I am not sure I will want to/need to do that.
Unk was one happy little camper as he sat with a draught of the Rebel Yell watching a late-night replay of Braves vs. Mets. Normally, I’d be right put out to be skunked this bad. I had not seen a single DSO after spending considerable time setting up the scope in the hot stickiness of a Possum Swamp summer’s night (heat index hit 101 in the afternoon). But not this time. Not only did I now understand how good the combination of PC and DSCs can be, I may have given my much -loved twenty year old telescope a whole new lease on life, muchachos, and that cannot be a bad thing.
Next Time: Destination Moon Night 6...
Hi Rod, I resisted goto mounts but aquired a CGEM a week or so after I retired. An unexpected benefit of using the goto CGEM is mostly ergonomic. I'm well over 6' tall and bending over and looking up through finder scopes often left me aching a bit and more so as I aged. Using the CGEM allowed me to only have to perform these awkward contortions a coupe of times to align the mount and thereafter only have to push buttons. Wonderful relief for my back and neck!Post a Comment