Sunday, June 23, 2013


Destination Moon Night One: 10 down, 290 to Go

Tell y’all the truth, despite Unk’s recent resurrection of his “if it ain’t raining, head to the dark site” rule, I was awful tempted to stay home and watch Svengoolie last Saturday evening. Heck, he was showing King Kong Escapes. And it was hot, muchachos, 90F at sundown. It was humid, it was buggy, and there were plenty of clouds coming and going. If I had been after the deep sky I probably would have stayed home. But I wasn’t.

As I’ve said here before, I am a Lunatic. I’ve been a sometimes-fanatical observer of the Moon since I got my 3-inch Tasco reflector five decades ago, and I’ve never grown tired of her. Which is not to say there haven’t been lapses, times when I’ve only viewed Diana’s silv’ry countenance casually and occasionally. The past several years were one of those times. I was all wrapped up in the Herschel Project, and my cotton-picking job meant I was lucky to get to the dark site once a month for a deep sky run with the Mallincam Xtreme.

That has all changed. I’m still tying the bow on the H-project, going back and acquiring better video images of the spring galaxies, but it’s no longer pedal-to-the-metal Herschel observing. An even bigger change is my engineering day job is history. I am retired now and don’t hesitate to head for the dark site on any clear evening, even an evening that ain’t so dark because Selene is sailing through the sky.

While I haven’t lost my love for the Moon, I am embarrassed to admit I’ve lost my familiarity with her. I am a long way from where I was when I was a sprout with an Edmund Scientific Palomar Junior, the days when I knew the Moon better than I ever have since, when I knew the nearside of Earth’s satellite every bit as well as I knew Mama and Daddy’s subdivision. Oh, I can still point out Copernicus, and Plato, and Mare Tranquilitatus, but don’t ask me where Hyginus, Birt, or dadgum Sulpicus Gallus are anymore. And I’ve been feeling bad about that.

What did I do when I was a little kid wanting to learn the Moon? I took Sir Patrick Moore’s advice to heart and set out to sketch the 100 most prominent lunar features. Actually, I kicked it up a notch from what Patrick recommended and planned to do all 300 of the craters, mare, and other formations on the Moon map in the old Norton’s Star Atlas. I never quite got that far, but I stuck to it enough to get in my hundred.  So, it’s not a surprise I knew ol’ Hecate purty well. Maybe, I thought, I should do the same thing now?

Or not. I still like astronomical drawing, as you know if you’ve been following my semi-regular Unk’s Messier Album series, but sketching is not a major interest at the moment. Imaging is. What if I took pictures of every single Norton’s feature? That alone wouldn’t be as good an aid to learning the Moon again as sketching would be, but what if I used Photoshop to label the features in my frames? I thought that would be a big help in finding my lunar legs again.

Alrighty, then. But how would I image the Moon? I was there at the dawn of the webcam revolution and still had my venerable SAC 7 modified webcam, as well as the slightly more modern Celestron NexImage (the original model) and Meade LPI. I’d shot a lot of Moon pictures with ‘em, and had been pleased with the results. But I had been out of the planetary photography game for over five years and hadn’t taken a Moon shot with anything but a cell phone cam in a long time. I knew the world had Moved On and there were planetary cameras far more sophisticated than my humble modified webcams.

I began reading the Cloudy Nights BBS’ planetary imaging forum—there’s a Solar System Imaging board on Astromart as well, but there is little or no activity on it. Three letters turned up frequently: "Z," "W," and "O." “ZWO," I found out, was the name of a Chinese company who appeared to be making a name for themselves in astronomical imaging. The company’s cameras were becoming a favorite with amateurs, it seemed, including top planetary imagers like Chris Go and Damian Peach. I headed for the (nice) ZWO website for a look-see.

What I found there were the two cameras that were being talked about the most on CN, the ASI120MC and the AS120MM. Both were similar, with the MC being one-shot color and the MM being monochrome. While the planetary hotshots were mostly using the MM, I thought the MC was more lazy old Unk’s style. I like color, and the chances of me ever doing tricolor imaging with a filter wheel are slim to none—at best.

How was the ZWO camera better than my old SAC 7? First off, the MC’s max resolution, 1280x960 pixels, obviously left the SAC and the other webcams in the dust. Even better, the frame rates claimed for the ZWO were amazing:  35 frames per second at max resolution, and a blistering 215 fps and 320x240. My old cameras might do 15 fps with a tail wind, but to get images that looked worth a hoot I had to slow down to 5 fps.  As you-all may know, the way most planetary imaging is done these days is by shooting .avi movies and stacking their frames into a finished picture. More frames faster is always better in our quest to defeat seeing, and the ZWOs offered way more frames per second than I’d been able to achieve with webcams.

What else? The MC’s chip, the spec sheet said, had 1.2 megapixels of the small pixels we crave for getting high-resolution Lunar and planetary shots. 12-bit image depth. USB 2.0 connectivity. Exposure times ranging from 64 microseconds up to 1000-seconds (17-minutes). Best of all for me was the price:  under 300 bucks, something even cheapskate Unk was (relatively) comfortable with.

After just a wee bit of hemming and hawing, I ordered the 120MC and sat back to wait for it. From what I could tell, it would be coming directly from China. That didn’t worry me like it would have in the past. I’ve ordered several accessories from Mainland China for my Baofeng UV5R HT (ham) radio, and they’ve all come quickly. Nevertheless, I was fracking amazed when the ZWO arrived. I ordered on Tuesday and it was on the front porch on pea-picking Thursday. I don’t know how ZWO head honcho Sam Wen does it, but he does.

I was even more impressed when I opened the box. The camera is a little thing of beauty, a long way from the plastic-bodied NexImage and Meade LPI I used for years. The ZWO sports a lovely red anodized body with cooling fins on the back. Naturally, there was a 1.25-inch nosepiece and a USB cable in the package, just like with the Meade and Celestron cameras. But…there was also a 1.25-inch IR block filter (needed to get a decent color balance with a planetary camera), and, get this, a fisheye lens. Not exactly sure what I will do with that. It was handy for testing the MC indoors, though, and I am thinking I might be able to use it to image meteors or some such.

The camera looked good and worked just like it should near as I could tell from my indoor tests. 'Course, the only real test for astro-gear is on the good old observing field. Which brings us back to last Saturday evening. Scope Nights on my iPhone was giving the night a “fair” rating, so I thought it was worth a try. Hell, if there was any chance of seeing anything, I’d have gone out to the site; I couldn’t wait to try the MC. At 6:45 p.m., I packed up the Edge 800, Mrs. Peel, her VX mount, the laptop, and a couple of accessory boxes and headed for the Possum Swamp Astronomical Society observing field.

There, I took my time setting up. Looked like the clouds had scudded off and that I’d have a good and long night ahead of me. That’s what I thought till halfway through setup I looked to the east. Uncharacteristically, there was a band of clouds on the horizon and it appeared to be heading my way. I was surprised, since weather systems usually approach us from the west. I knew I had dern sure better shake a leg.

Unfortunately, not only was it still too early to see go-to alignment stars at 8 p.m., Polaris hadn’t peeped out, either. Yet, Selene was shining brightly and was just past culmination. I fiddled around for a few more minutes, till I was absolutely sure the clouds were coming my way, and took the bit in my teeth.

I polar aligned the VX by the simple expedient of pointing its R.A. axis roughly north with the aid of my compass. Go-to alignment? That wasn’t much of a concern since I’d be staying on Luna all night long. I selected “Solar System Align,” and “Moon” with the hand controller, and the mount headed for where it thought Luna ort ta be. When the VX stopped, it was a few degrees away from Selene, but only a few. I centered the Moon in Emma with the aid of my new Rigel Quickfinder, hit “Enter” and “Align” and the VX responded with “alignment success.”

Hokay, time to get to work. I removed the diagonal, crosshair eyepiece, and visual back from Mrs. Peel and replaced them with the Meade flip-mirror I’ve had for over a decade.  A flip mirror is a godsend for planetary imagers, though it was originally intended for deep sky CCD users in the days of uber tiny chips. Now that even planetary cams have larger sensors (the 120MC’s is a 1/3-inch CMOS job), there is not much demand for flip mirrors, but they can make the extremely difficult (make that “near impossible”) job of centering a planet or even the Moon at f/20 or f/30 downright easy.

How does a flip mirror help? One is like a special sort of diagonal. Actually, they are diagonals. There’s an eyepiece tube, and, on my Meade, a threaded ring so I can screw it directly onto the SCT’s rear. The difference is that there’s a port on the back of this special diagonal for a camera with a 1.25-inch nosepiece.

When you have the object of your desire in the eyepiece, you turn a knob, which FLIPS the diagonal’s mirror out of the way, and the light from the scope goes straight through to the camera. There’s a helical focuser on the eyepiece tube that can be adjusted so the camera and eyepiece are in focus at the same time. That means you focus the Moon or a planet, flip the mirror up, and it is on the CCD and sharp. There are adjustments for the mirror to ensure that what’s in the eyepiece is also on the chip.

I inserted the ZWO into the flip mirror and had a look through the eyepiece. Miss Selene was well centered, so I flipped the flipper, and headed for the laptop. Next step was plugging in the camera. I got the reassuring bing-bong that indicated the camera driver I’d installed when I got the ZWO (a little CD with the driver and a few simple imaging programs is in the box with the MC). Booted-up the camera control program I’d use on this evening, the outstanding freeware Sharpcap, and saw…absolutely nuttin’, honey. Sharpcap had recognized the camera immediately, and seemed to be working properly, but the consarned preview display was as black as the inside of my black cat, Thomas Aquinas, at midnight. Rut-roh.

I finally got the camera working, but in typical Unk fashion, it took some fumbling and bumbling. What was the problem? A combination of things. There was now a thin layer of clouds dimming the Moon appreciably. The focus point for the ZWO was different from the last cam I’d used with the flip mirror, the SAC7, so eyepiece and MC were not in sync. Finally, I didn’t have a feel for the camera’s exposure settings yet.

As an aid to getting something visible, I removed the Barlow I’d placed ahead of the MC and shot at f/10 initially. Still nothing. Then I noticed an “auto exposure” checkbox on Sharpcap, checked that, and soon had a fuzzy white something on the monitor and, not long after, yep, craters.

From there on out, it was all gravy. There were some stretches of clouds, but I got about a half an hour of clear sky all told. The bugs were fierce, but the Thermacell kept most of them at bay. It was hot and as humid as humid can be, but a Monster Energy Drink kept Unk going. The MC? Once I got a feel for it, I upped the focal ratio back to f/20 with the Barlow, and the camera just zipped along, delivering around 40 - 50 frames per second at a resolution of 800x800, which I thought was a good compromise, delivering plenty of frames but in a reasonably large size. 

After shooting most of my sequences at 800x800, I upped the resolution to the max, 1280x960, to see what would happen, and after I'd processed 'em the next day, I decided the big pictures (below) looked every bit as good as the smaller ones. It sure is nice to have larger images to work with. Color is also nice, but I found I still prefer to process the Moon in black and white. With me coming from the days of shooting Luna with Tri-X, it just seems "right."

What did I image? I got in three areas before full overcast set in: Aristoteles/Eudoxus, Hipparchus, and the area of Bessel on the shores of Mare Serenitatus.  The seeing, unfortunately, wasn’t very good, though it improved somewhat as the evening wore on, and just before the clouds smothered the whole dern sky I rated it “fair – good.”

By 10 p.m., it was completely overcast and I was not at all reluctant to pull the Big Switch. I was hot and sweaty and just this side of miserable. The Monster I’d had earlier left me a little jumpy, y’all, an effect the stuff occasionally has on me on nights when I am approaching overheated. I was OK as long as I had company, a couple of the friendly folks who live near the field, but when they left, my hot and tired and wired state encouraged me to begin thinking idly about big smelly ape-men, little grey aliens, and that dad-blasted Mothman. "That rustle in the cornfield south of the airstrip? Just the wind, right? Uh-huh." That settled it—time to head back to The Old Manse.

At home with the gear inside and semi-stowed, I poured myself a soothing portion of the Rebel Yell, turned on the cable TV (a Ghost Adventures marathon was in progress), and tried to settle in. I couldn’t.  I was just too anxious to see what the ZWO had been able to achieve. I prefer to work on our desktop when possible, so I copied a couple of the image files on the laptop to a DVD. I had a bunch, and 30-seconds at a high frame rate produces large files, close to 2.5 GB, so all of ‘em wouldn’t fit on one disk. I picked two likely-looking ones and loaded them into my stacking program, Registax 6, on Chaos Manor South’s kitchen workstation.

I’d had the good sense to get back up to speed with Registax and learn the current version while waiting for Luna to come back around, so it wasn’t much trouble to align and stack one of my Aristoteles sequences. Did a quick sharpening with Regsitax’s famous “wavelet filters,” and I was done and was impressed. I thought it looked pretty dadgum good for my first real Moon picture in years, given the not-so-hot seeing and a camera and software that were new to me. I headed upstairs tired but happy.

Next morning I was up early even if I wasn’t feeling too bright after less than five hours of shuteye. A few cups of coffee, and I was ready to process the rest of my files, most of which came out considerably better than my hasty effort the night before had. A little messing with the wavelets, a little tweaking with Photoshop, and there was no doubt my results were at least as good as the best I’d ever done with the LPI, SAC 7, and NexImage. Which is not surprising; this camera is in a whole ‘nother league, campers, and I think this is gonna be the beginning of a beautiful friendship.

Only one more step remained before I could close out Night One of what I am calling my “Destination Moon” project:  label the features in my finished pics. Which was easy with the aid of what is in my opinion the best Lunar atlas available, Patrick Chevalley’s and Christian Legrand’s amazing Virtual Moon Atlas. I did a post on it a while back, but it is even more incredible now, with a huge array of features and data. Go get it, y’all, it’s free. VMA, whose highly detailed charts can be flipped and rotated, made it easy for me to label the major features on my images. And even some minor ones. I kinda got carried away, I reckon.

What’s next for the ZWO and me? More of the same. Oh, I might try it on Saturn some night, but for now, the Moon is our focus. I covered 10 features on this first outing, but that still leaves 290 to go. How will I do those 290? Probably about like I did the first batch, with Emma and the VX on the PSAS field. Only change I might make is to try a new camera control program I’m hearing a lot about, Firecapture. Sharpcap is the bee’s knees, but, as you know, muchachos, old Unk is not immune to the allure of More Better Gooder, especially when that more better gooder is in the form of FREEware. Stay tuned.

Next Time:  Space Truckin’…

The Moon is for me the most alluring object in the Solar System. I've named my observatory "Sentinel" after Arthur C. Clarke's short story "The Sentinel". I believe I'll take your advice and replace my modified Radio Shack webcam with a ZWO. I'm too old to put off any gratification when it comes to equipment buying. Thanks Uncle Rod.

In your opinion would either the ASI120MC or ASI120MM be a good autoguiding camera? I'm thinking of purchasing a Orion autoguider and it would be nice if I could purchase a camera that has dual functionality.

John D.
Hi John:

I believe one would work at least as well as the Orion StarShoot guider (which works well for me)...and I see ZWO has just added an ST-4 port to the camera.
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