During my last trip to Arkansas, I worked alongside my stepdad’s dad to finish my homemade parallelogram binocular mount to the point where it’s useable. It still needs some cosmetic work; a final sanding and oiling, and maybe reworks to the binocular head, but overall, I’m very happy with it. It makes using binoculars a dream, and enables sketching, which would be near impossible with large binoculars being used handheld.
I finished construction on our last day in Arkansas, and set the mount out on the balcony to wait for dark while I packed my things. Ordinarily, I’d go to bed early since we’d have to get up early to leave in the morning, but there was a first light of a sorts to be had, and so I told myself “Just be in bed by 1:30.”
First light for the mount was of A Starfield Near Deneb; after which I swung over to 61 Oph and 39-o Oph for focusing. I was able to split both, though 39-o Oph was actually harder than the previous night when I had been using the binoculars handheld. I wonder if seeing affects binocular doubles? Let’s see, at a separation of 10.3″, 39-o Oph would be close in a telescope, but not affected by seeing. Dawes’ Limit for a 70mm aperture is 1.66″, meaning that at 15x, stars are nowhere close to being resolved into airy disks. That would point to seeing not affecting the view, in my mind.
After carefully focusing and logging the doubles, I did something I’ve wanted to do for a while- panned over to the Virgo Cluster, which was just beginning to set behind the house, pulled up a chart in SkyTools, and just started browsing. I panned back and forth along the roofline, scouring the view for galaxies just before they set, and running my voice recorder. In the end, I had thoroughly described M86, M84, NGC 4438, M87, the combined glow of the Siamese Twins (NGC 4567 and NGC 4568), NGC 4564, M58, M60, M59, M90, M89, M91, M88, NGC 4762, and NGC 4754, all in the span of 37 minutes. Not bad for 15×70 binoculars! I bet I could run a Messier Marathon with these. Or at least use them to get through the fabled “Virgo Sprint”! With the wide overview of binoculars and SkyTools open on the table, identifying galaxies was no trouble at all.
You can read my Virgo Cluster log here.
After my study of the Virgo Cluster, I paused to attempt a challenge I had been given: Spot Vesta with the naked eye. The challenge proved itself to be trivial, and as soon as I could identify it on the chart I was able to spot it in the sky. It’s somewhat surprising to me that it wasn’t detected until 1807. Remaining above magnitude 7 for five months at a time and above mag 6 for two months should have made it noticeable to the ancients- but one supposes they had more important things to do than note the positions of faint stars.
I do have to argue some of Phil Harrington’s statements in his “Cosmic Challenge” article about Vesta this month (not the source of my challenge; apparently the person who challenged me did so after reading Phil Harrington’s column.) He said: “Back here on Earth, Vesta has the distinction of being the only asteroid to crack the naked-eye barrier.” If we take the commonly-cited-among-professionals value of 6.5 for the faintest possible NELM (ugh), then Pallas also cracks the barrier at brightest by two hundredths of a magnitude. (!) But if we take a more realistic value of 7.5, the faintest that I’ve ever personally observed from Bortle 3-4 skies, then in theory Vesta, Pallas, Ceres, Iris, Eros, Hebe, Juno, and Melpomene ought to all be visible to the naked eye, barely, at opposition. (Source: Wikipedia “list of exceptional asteroids”.) Of course, this assumes the oppositions occur near to their perhelions, and most importantly that the asteroids are placed directly overhead- which seems highly unlikely. So a more practical list would probably keep it to below 7th magnitude, limiting the list to Vesta, Pallas, Ceres, Iris, and Eros – still significantly more than just Vesta.
Based on my observation, I also have to argue with Phil Harrington’s statement as follows: “Unfortunately, Vesta is also currently passing through Sagittarius, an area so full of faint stars that trying to figure out which one it is will prove quite challenging indeed.” As I said earlier, identifying Vesta was no problem at all. Though it was silhouetted on a bright portion of the Milky Way, it was also a particularly “milky” portion, with very few actual stars resolved. Vesta appeared several degrees away from any other stars, and at the time I observed it, was placed near a convenient asterism which I had already used that night, making location quite easy.
After Vesta, I turned to the my real purpose of the night: Creating a detailed sketch and log of the first H.A.S. VSIG Object of the Month, NGC 6633. NGC 6633 just happens to be my favorite NGC open cluster, so I was determined to do it justice with views in a telescope, in binoculars, from the city, and from dark skies. I had already sketched it from my city backyard using my Orion XT8, so now it was time to get a sketch from dark skies using binoculars- and I was especially excited to study it with my fantastic new Oberwerk 15x70s.
The view in the 15x70s can’t beat my first views of the cluster in my 8″ for sentimental reasons, but the 15x70s may just be the ideal instrument for viewing this cluster. The cluster was obvious, plenty bright enough to see all the main component stars, and at the perfect scale. It was just small enough that you could take it all in at once, and just big enough that you could see all the detail it held. The binoculars revealed the large starfields in which the cluster is embedded, and even a subtle complex of dark nebulae snaking around from the left. The starfields and dark nebulae were indeed subtle in this region of the milky way, and only became clearly apparent after sketching the field for hours, but they were an immensely rewarding detail to capture.
With NGC 6633 centered in the binoculars, IC 4756 lies just outside of the field of view. They both can be held in the same field, but they’re placed so close to the edge that abberations significantly degrade the view of each, so they’re best panned back and forth between. IC 4756 and NGC 6633 are one of my favorite contrasts in the sky; NGC 6633 smaller, bright, sparse, strongly shaped; IC 4756 larger, faint, extremely rich, fairly round. Seeing both in the same field of view may be the one case where 10×50 binoculars have an edge over these 15x70s, but in all other cases, the 15x70s dominate- at least if the 10x50s in the comparison are my peculiarly dark pair of Bushnell Instafocuses. (Oh, well perhaps the Bushnells do have an edge on focusing, too. 🙂 )
After soaking in the sight of NGC 6633 and IC 4756, I fetched my sketchbook and a pencil. Unfortunately, every pencil that I had access to had the hard, petrified rubber eraser- which as I’m sure everyone who’s used one of those unfortunate pencils knows, tend to just smear graphite instead of erasing it even a little. That’s alright, then: I just wouldn’t use an eraser. In art, they advise you to draw without using an eraser to overcome perfectionism; so I decided that was what I would do. Misplace a star? In a field this rich, who will notice?
It quickly became clear that in a field this rich, there was no way I’d be able to place each star individually and precisely, as I usually do. I’d have to resort to stippling at some point. So the brightest stars were very precisely placed, the medium stars were approximated relative to their nearest bright stars, and the “shape” of the faint starfields was approximated with stippling.
I traced a circle onto my sketchbook with the front objective of the binocular, and started the sketch at midnight. My target bedtime of 1:30am came and went with the sketch nowhere near being done. But somehow, I didn’t mind. Sketching is often a huge chore for me; it’s difficult, which I could easily stand if it was fun like observing, but it often turns out mind-numbingly boring. I always power through it because the final sketches are so valuable to me as a way to remember my observations. Several times have I pulled up an object into the eyepiece, and been so impressed that I disappointedly think “Aw, I’m going to have to sketch this, aren’t I?” But NGC 6633 was so beautiful, the binoculars so easy to use, that when three hours had passed and I put the finishing touches on the sketch, I wasn’t hating it. It was still tedious, but not as bad as I often encounter. And the final result is by far one of my favorite sketches that I’ve ever made.
There were challenges encountered and misadventures had along the way; my red flashlight ran out of battery, so I had to use one of those little red keychain beacons that they sell at McDonald Observatory. You could use one as a taillight. I made do by wrapping it in my shirt and clutching in my fist, varying how hard I was clutching it to change the brightness. It made sketching awkward, but I persevered. Maybe part of my stubborness was due to the head trauma: while I was sketching, sitting in a chair under the bino mount up on the balcony, I suddenly heard the now-familiar sound of hunting raccoons below the balcony. It didn’t get me quite so strongly as the first time, but I did stop observing to listen to the sounds of vicious snarls and something small dying. (Boy, am I glad there was a balcony!) While I sat there, listening intently, the bino head, which had been rather solid up until this point, suddenly slipped in both altitude and azimuth and those 5.5 pound premium binoculars flipped over and clocked me in the head! I then had to halt my sketching to venture down to the shop for a screwdriver to tighten the bearings back up again. Fortunately, my mental faculties still seem to be more or less intact 😉
NGC 6633 forms a prominent asterism, which is what I see every time I look at it. To me, the cluster appears to be clearly shaped like a cartoon shooting star. There’s a spiky ball (more like a triangle), which makes up the commonly recognized cluster and the “star” or head of the meteor; and then three bright, parallel, arcing star trails leading away from that, forming the tail of the shooting star. (Those star chains don’t seem to be commonly recognized as part of the physical cluster, but the Gaia DR2 data shows them to all lie at the same distance.) In my sketch, the spiky star shape is in the lower right, and the three star chains which form the tail trail away to the upper left.
The cluster actually forms another prominent asterism, but this one, I did not notice on my own, rather heard of online. In my telescopes, the view is too zoomed for it to be visible, but when I remembered about it in the 15x70s, it was easy to see. That asterism is the shape of Italy, complete with Sicily and even Palermo if you use a little imagination. In this case, the spiky “star” portion becomes the heel of the boot, the arcing star trails become the leg of the boot, and you have your pick of the nearby star HR 6928 signifying Palermo or the triangular-shaped starcloud west of HR 6928 representing Sicily (the two are separated by enough to make Sicily a bit awkward on paper if you include both, but the human brain is great at seeing two things at once).
Here’s an illustration demonstrating both asterisms:
I recorded a long log on my voice recorder to accompany my sketch, which you can read here. Comparing my Virgo Cluster log with my 3am NGC 6633 log, my tiredness shows through!
I submitted my telescopic and binocular sketches and three logs of NGC 6633 to the VSIG coordinator, and hopefully at least the sketches will be included in the writeup. I’m excited about the new Object of the Month program, and looking forward to more interesting targets in the future- though having more challenging ones too wouldn’t hurt.