Uncle Rod's Astro Blog

The good news, muchachos? I’ve been getting clear skies, and with a fat Moon hanging over (the new) Chaos Manor South this past week, it was time to get back to my Destination Moon project. That’s my quest to observe the 300+ lunar features shown on the Moon map in my old Norton’s Star Atlas 15th edition, the hallowed book that helped Unk navigate the sky as a sprout.

‘Course things are never as simple as they seem when it comes to amateur astronomy, are they? While passing cold fronts had brought surprisingly transparent air, they also brought unsteady air, lousy seeing. And that is a bad thing, y’all. What matters most for lunar and planetary imaging and observing? It ain’t your scope. It ain’t your camera. It ain’t light pollution or a lack thereof. It is good seeing, a steady atmosphere for your telescope to peer up through. As the years have passed, I have ever more come to realize that is really the be-all and end-all for the Solar System.

I will say, however, that the Moon is a little more forgiving in that regard that, say, Mars. If the seeing is bad enough, you won’t see much of Diana, but on semi-punk nights, you can shoot a lot of frames and hope to get some good ones in-between atmospheric disturbances. Which is just what I did. Project DM had been idle for over two months, and it was high time to get into the backyard and start kicking the crater count UP.

Before we go there, howsomeever, a couple of things. First off, I promised y’all I’d let you know how the C102 who recently came to live at the New Manse, did on the Moon. If you read that linked blog article, or are familiar with Celestron’s refractors, you know Miss is an achromat, a 4-inch f/10 achromat. To be nearly color free, she’d have to have a focal ratio of f/15, if not f/20. At f/10, I knew there’d be some color.

My awareness that there would be shades of deep purple on the Moon didn’t just come from theory. I’ve used more than a few 4-inch achromats over the last 50 years, including another C102 that Pat Rochford, who gave me this one, owned years ago. The night I looked at Luna through Pat’s previous C102, almost 14 years back, still seemed fresh in my memory. And what was in that memory seemed to be lots of purple. Not just on the lunar limb, but on the terminator, with the shadows of craters and other features being a fraking Technicolor riot. 

Memory can be deceiving, however. Often, we remember what we want to remember, or our mind simplifies our memories into sharper gradations of black and white (or purple). I knew that, and tried keep an open mind. I’d just see what she could do, and if my memories of that long-ago C102 in Pat’s yard turned out to be accurate, so what? The refractor would continue to do a great job on the deep sky and double stars.

I waited until Luna was high in a dark sky before lugging the scope and her AZ-4 mount out onto the deck. She only takes a little while to acclimate to our mild (for the Yankees among y’all) outdoor temperatures, and in just a few minutes she would begin delivering her best images. Anyhoo, I wanted the Moon to be as bright as possible to provide a stringent test.

Hokay, then. Inserted my beloved Zhumell (aka “TMB”) 100-degree AFOV 16mm eyepiece, the vaunted Happy Hand Grenade, in the Intes 2-inch star diagonal, lined up the Moon with the 50mm RACI finder and had a look…

Verdict? Dang, just dang. The terminator was just so sharp-looking in typical refractor fashion. The welter of craters in the southern highlands was bewildering. Away from the terminator? That is where a fast achromat has trouble; the terminator may look sharp, but get out on the disk and contrast goes to pot. Not with this scope. Features well away from the day-night line remained satisfyingly sharp.

“Alright Unk, that’s fine, but you know what we want to know.” Oh, I know, alright. How was the color? It depended. On the eyepiece, on the magnification, on the position of my eye on or off axis. On the limb, there was sometimes no purple at all, just a yellow-amber rim. At its worst? There was a prominent but not overwhelming blue-purple outline to the Moon’s edge. The terminator? There was a purple tint to the shadows, but it was hardly as strong as I remembered, and after a few minutes of concentrating on observing, I purty much forgot about it.

Curiously, the amount of purple in the image, whether on the limb or the terminator, didn’t seem to depend just on magnification. It also seemed dependent on eyepiece type, with there being considerably more color visible with a 20mm Plössl than with my 22mm Panoptic. The picture at left, taken by the simple expedient of pointing my cell phone down into a 35mm (Panoptic) eyepiece, suggests how Luna looked much of the time. One caveat? Unk’s eyes; his eye doctor tells him they are well on their way to needing cataracts removed. In other words, I now have built in mild yellow filters, I reckon.

Other than chromatic aberration, how was the scope’s performance? Amazingly good. The sharpness held in at nearly 300x despite seeing that was nothing to crow about. There was nothing in Rukl’s Atlas of the Moon, which I had beside me, that wasn’t at least hinted at in the eyepiece. One thing that is different for someone coming from reflectors? The Moon looked warmer, more yellowish, at all powers than in a Newtonian or an SCT. That is not necessarily bad; in fact it’s kind of attractive. But it will be different from what you are used to if you’ve never seriously viewed Luna with a lens scope.

Given the C102's superb account of herself on the Moon, only one question remains:  “How will she do on the planets?” Mars, unfortunately, while still hanging on in the west—where he will remain for quite a spell—is tiny and in the trees. Old King Jupe, however, is beginning to come into his own. Right now, he’s rising at just after 10 p.m. and will soon be high in the mid-evening sky. When he’s up good at 10 or 11 in the p.m., your tired old Unk will visit him with the refractor and you will hear how she does.

Despite me having outlined my lunar imaging set-up a couple of times in this series, I am still getting questions about it, so bear with me while I again summarize my rig for those of y’all getting interested in exploring the Moon with a camera yourselves.

While I said the telescope is not the most important thing in lunar imaging, not compared to seeing, it is still important. For high-resolution closeups, you want something that’s got a lot of focal length, whose focal length can be easily increased, and which will easily come to focus not just with a camera, but with Barlows and other stuff in the light path. For high-resolution photography of lunar details, the place you start is at 4000mm. How do I get there? I start out at 2000mm with my 8-inch Schmidt Cassegrain and double that by adding a 2X Barlow in front of the camera (“Barlow projection”).

I do not, however, insert the Barlow and camera directly into the scope’s visual back. Instead, they go in a widget called a “flip-mirror” that is screwed onto the C8’s rear port. When I began doing high focal ratio imaging of the Moon, I quickly discovered it’s almost impossible to get even the big Moon in the field of a small-chip camera with just a finder scope. Even a carefully aligned finder scope. It was difficult enough to make me want to give up and carry the scope back inside before I’d taken a single shot.

A flip-mirror will preserve your blood pressure and hairline.  It is much like a star diagonal, but with some important differences. In addition to an opening for an eyepiece, there’s another port, on the rear of this “diagonal” for a camera. And the diagonal’s mirror is moveable. You flip it down to send images to the eyepiece, and up to send them to the camera. Find the Moon with the eyepiece, flip the mirror up, and it will be in the field of your camera. This is a huge aggravation preventer, and if you plan to do much lunar and planetary picture taking, even with a goto mount, you want one. A goto will put you on the Moon, but the flip mirror will help you find individual features.

Then there is the camera. Like many of today’s Solar System workers, I am using a ZWO camera. This little wonder is somewhat like a webcam and somewhat like a CCD camera. It can take many frames per second—up to 30 at its max resolution of 1280 x 960 and many more at lower resolutions. Years ago, amateurs found the way to attain high-resolution Solar System images is to take many frames and use special software to stack the best ones, those captured during the moments of best seeing.

That’s not all this little cam can do, however. It can expose for as long as 16-minutes, more than enough to capture galaxies and clusters. While it is uncooled and has a small (1/3-inch) CMOS chip, folks have taken amazingly good deep sky images with it. I even use mine for capturing stellar spectra with RSpec. The current versions of the camera also feature ST-4 guide ports, so you can use ‘em as guide cameras. Unk owns the color version, the ZWO ASI120MC, but a monochrome version, the MM, is available for just a little more money and is even sharper and more sensitive.

The ZWO has no way of storing images; it simply sends an .avi video stream to your computer via a USB connection. You must have a computer and software to control the camera and save video on the hard drive. While the ZWO will work with many programs, the best I’ve found, the best software I’ve used for this purpose after a dozen years of working with similar cameras, is the free FireCapture.

When you’ve got those .avi videos on your drive, you stack their individual frames into finished still images. What I am using to do that is an old favorite of a program, Registax. While a new soft, Autostakkert, has a lot of fans, I have had varied success with it. Sometimes it works better than Registax; sometimes I can’t get it to work at all. That’s likely pilot error, and I am continuing to play with the software.

I told y’all I use an SCT for my Moon pictures, but I didn’t mention which one. While I’ve used my Celestron Edge 800, Mrs. Emma Peel, with great success, I’ve mostly worked with my 1995 Ultima OTA, Celeste. Why? Simply because she is set up to use a JMI Motofocus motor, which makes getting sharply focused images easier.

The night after I took the refractor into the silv’ry moonlight, I was out again with Celeste and my ZWO cam. I’d set up in the late afternoon with the scope positioned on the ground next to the deck. I’d sit at the table on the deck with the PC and run the show from there. Before I could get going, though, a couple of things intervened. First, Pat called needing advice on getting his new SynScan mount going to its gotos properly. When I rung off with him, I noticed the consarned Moon had still not cleared the gum tree. That tree’s days are numbered, y’all, I swear.

When the Moon was out of the limbs half-an-hour later, I headed back outside and set the laptop up on the deck. First thing I noted? At 7:30 p.m., the glass tabletop was already wet with heavy dew. Rut-roh. I hadn’t installed the DewBuster heater and heater strips on the scope. Usually, I can get by with just a dew shield in the backyard, but not on this evening.

A check of the corrector showed it was, yep, fogged. I got my little dewzapper (12-volt window defroster) gun out of the shop and zapped the dew off. I knew it wouldn’t stay off, so I headed inside and returned with the ‘Buster and a corrector heater strip. Got those things on Celeste, turned the controller up to 10-degrees above ambient, and there was no more trouble with dew for the remainder of the evening.

Next, I did a 2 + 4 goto alignment with the VX mount, and then essayed an AllStar polar alignment (at high focal ratios, good tracking is important). With the VX purring, I cabled the camera to the Toshiba Satellite laptop with a USB cord, and ran the motofocus motor’s cable to the deck (using extensions) so I could sit at the computer and focus.

When all that was “go,” I booted up FireCapture, got the lunar terminator focused, and started the other software I use during lunar imaging, Virtual Moon Atlas. Not only does VMA help me navigate the maze of lunar craters, its Notes function informs me as to whether I’ve already imaged a particular feature or not. When I am finished with a crater or mountain, I select it and enter “imaged” and the date in VMA’s “notes” tab. It’s a little like using a deep sky planner/logger for the Moon. Oh, as I have mentioned here before, VMA also provides lunar goto.

Why would you need goto for the freaking Moon? It is a tremendous time-saver. Even if you are reasonably familiar with the lunar surface, like Unk is once again becoming, it’s easy to get lost when you are looking at a very small portion of the surface at f/20 with a small chip camera. VMA uses ASCOM, so I can use the on-screen ASCOM “hand control” to center a crater without worrying about fooling with the mount’s HC. When I’ve got a known feature in view, I “sync” on it with VMA and am good to go. I accidentally synced the program on the wrong feature in the beginning this time, and it took me a while to get that sorted, but before long me and Celeste was rolling.

So, what did we roll with?

Klein

I thought I’d start with Albategnius, a large and impressive formation adjacent to the crazy-good triple threat of Ptolemaeus, Alphonsus, and Arzachel. Unfortunately, my Notes entry said I’d already gotten it. The seeing was briefly steady, though, and as I had not officially shot the smaller crater that intrudes on the east wall of Albategnius. I centered up Klein and fired off a thousand frames.

Klein, which is medium-sized, 45.0 x 45.0Km, is interesting, with a mostly flat floor, but one that is festooned with numerous small craters and a central peak. This crater is old, apparently dating from  the Nectarian Age (3.92 billion to 3.85 billion years ago), and looks it, with its rim having been badly pummeled and covered with smaller craters.  

Archimedes

After Klein, I temporarily headed back north where I noticed the fantastic dark-floored crater Archimedes was emerging from lunar night. Frankly, I was surprised I hadn’t photographed this one before, but I hadn’t. At First Quarter, Archimedes is particularly prominent. It is also set in an intriguing area on the shores of Mare Imbrium not far from the lovely crater pair of Autolycus and Aristillus.

What is Archimedes like? This  83.0Km. round crater is a lot like Plato, with a dark lava-covered floor scattered with craterlets. With it just coming into the dawn, the shadows from Archimedes’ mountainous rim obscured much of the floor in my shot, but were very photogenic. Looking at those shadows, you can sure see why pre-Apollo space artists like Chesley Bonestell portrayed the Moon’s mountains as needle-tipped spires. Archimedes is a middle-aged crater dating from Upper Imbrian (3.8 billion to 3.2 billion years ago) times.

Theaetetus

Just to the north of Archimedes’ area, you’ll find nice smaller crater, Theaetetus. While it’s only 25Km. across, it looks prominent thanks to steep, sharply defined walls. The crater, which likely dates from the Copernican Age (1.1 billion years ago to present day), is far younger and more fresh looking than most of the formations in the region.

Mons Piton

Also to the north of the Archimedes area and out in the “waters” of Imbrium is one of the non-crater formations on my list, Mons Piton, a 2250 meter peak peeping above the lava sea. Dating from Imbrian times, Mons Piton looks steep and sharp, though Apollo images show it as rounded and “weathered” like other lunar mountains. This area is littered with solitary peaks, the remnants of lava-drowned mountain ranges.

Herschel

If it were located anywhere else, the medium-sized (42km.) and young crater Herschel (named for Sir Willie himself, natch) would be a real standout. Unfortunately, lying just to the north of the trio of Ptolemaeus, Alphonsus, and Arzachel means it gets overlooked. It is attractive, however, with terraced walls and a complex floor, which was unfortunately still in shadow when I made its portrait.

Ptolemaeus

Now here’s a crater for you—though it should really be called a “walled plain.” Ptolemaeus, with Alphonsus and Arzachel, is the most distinctive feature of the First Quarter Moon. Ptolemaeus is the largest of the three big craters at 154.0 x 154.0Km. While distinctive, it is old and softened, having been formed in the Pre-Nectarian Age (4.55 billion years to 3.92 billion years ago.

The floor of this great walled plain is surfaced with lava and cluttered with numerous craterlets. One of those craterlets, Ammonius, is large and prominent enough to bear a name rather than just a letter. The south side of Ptolemaeus has been intruded upon by neighboring and younger Alphonsus.

Alphonsus

My favorite crater? Like most other folks, it’s Copernicus. But Alphonsus is in the running, y’all; it is magnificent. Despite its age—it dates from the Nectarian—it is still well defined and offers a ton of detail for visual observers:  a craterlet-riddled floor, a compact central peak, and an extensive network of rilles. Due to its large size of 118Km in diameter, it, together with the two neighboring craters, Alphonsus and Arzachel, puts almost everything else on the terminator at First Quarter to shame.

There is also romance wrapped up with Alphonsus. Do you know about Transient Lunar Phenomena? Also known as Lunar Transient Phenomena (LTP)? Over the centuries since humans began scrutinizing Luna with telescopes, odd things have been seen on her surface—glowing clouds, obscuring mists, and strange lights. Alphonsus has been the site of numerous LTP reports, including a famous one by the Russian observer Kozyrev in November 1958.

Kozyrev didn’t just see a glow on the crater floor, either; apparently he obtained a spectrum of it (which seemed to be the emission spectrum of carbon). Do I “believe” in LTPs? Maybe not as strongly as I believe in another legendary Solar System mystery, Venus’ Ashen Light (which I’ve seen for myself), but I do think some of these weird lunar phenomena are real, whatever they are.

Arzachel

If Alphonsus is in the favorite-crater running, Arzachel, the third of the First Quarter Big Three, is right behind Copernicus. While it is smaller than Alphonsus and Ptolemaeus at 98.0Km. across, it is slightly younger than its mates, dating from the Lower Imbrian. It looks fresher, and more like a crater than a walled plain. Its terraced walls and a central peak accompanied by a large craterlet and a rille are a sight to see at lunar dawn.

Walther

We have to journey south of Arzachel across 460Km. of increasingly rugged lunar terrain to come to our next stop. Walther is another flat-floored walled-plain with a lot to offer observers. At 141.0Km. in size, it stands out well even in small scopes. Alas, nobody much seems to look at Walther—I don’t hear it much talked about anyway. Appearance-wise, this is an old formation dating from the Nectarian, and looks it with heavily damaged walls and a “tormented” floor. The northeastern area of the crater’s floor has been heavily pounded and is a welter of ridges and large craterlets.

Aliacensis

Aliacensis lies northeast of Walther, and is adjacent to a similar-sized crater, Werner.  Like Walther, Aliacensis is from the Nectarian, and has a soft look in contrast to younger Werner. At 80.0Km in diameter, Aliacensis is nevertheless impressive and sports many craterlets and wrinkle-ridges on its flat floor along with a small, heavily weathered, off-center peak.

Pallas

With haze and fog creeping in, I hopped back north to the area of the Central Sea, Sinus Medii, for one last pickup.  This location, between the rough southern highlands and the northern plains is detailed and interesting and includes the Triesnecker Rille, the oddly shaped crater Ukert, and more. Pallas itself is a heavily damaged walled plain 50.0Km across that comes from Nectarian times. There’s a large and rounded central peak, and a gap in the walls to the east that gives passage into an even more heavily damaged crater, Murchison.

And just as I clicked off the last few frames of Pallas, the fog began to move in in earnest. Shortly, I was drenched and so was the laptop. If I’d a-had good sense, I would have put up the patio table’s big umbrella, which would have kept me drier, but, alas, I didn't have good sense. I hoped I had a pretty good haul of lunar images, anyhow. Big Switch Time.

Next morning, as I began processing my sequences and ticking them off the old Norton’s list, I was pleasantly surprised, mucahchos. The seeing hadn’t been great, but Registax was able to pull out plenty of pleasing detail. It is unexpected triumphs like that that keep me coming back to my lunar imaging project. Actually, I’d keep coming back to the Moon, project or no. Diana’s silv’ry countenance has kept me enthralled for half a century, and there’s no sign our love affair, at least, is going to wane.

Next Time: As is our custom here, the next edition of the Little Old Blog from Chaos Manor South will not appear next Sunday, but on Christmas Eve and will likely be a tetch shorter and more sentimental than usual...