Archive for November, 2015

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Observing Reports: two perfect imperfect nights at the Salton Sea

November 23, 2015

Apex 127 ready for stars 2015-11-14

The Saturday before last, November 14, I was at the Salton Sea with Terry Nakazono.

Terry Nakazono with Meade Polaris 114 2015-11-14

Terry was rolling with a new scope – a Meade Polaris 114. It’s an f/8.8 reflector – the 1000mm focal length makes it a bit longer than the 900mm, f/7.9 Orion XT4.5 (which London has). UPDATE Nov. 29: Terry writes, “It’s a standard 900mm FL, not 1000mm. A lot of the retailer ads have it wrong and says its 1000mm. I myself was intrigued when I first read about it, but later found out from looking at the PDF manual and those who bought it is that it is an F/7.9 of 900mm focal length.” So it’s not longer than London’s XT4.5, it’s essentially the same OTA.

This Meade is a pretty amazing deal. A lot of small intro reflectors have a short dovetail bar bolted to the side of the tube (like my old scope Shorty Fats), but this one has real tube rings and an EQ-2 mount. The three MA (Modified Achromat) eyepieces it comes with are nothing to write home about, but the focal lengths of 26mm, 9mm, and 6.3mm are at least useful and non-overlapping when doubled with the included Barlow. Terry shared a few views with me and I can confirm that it serves up a sharp, contrasty image, as you’d expect for a scope of this focal ratio. It would be a good deal at the list price of $170, but Amazon has it for $135 as of this writing, and according to Terry it can be found for even less if you look around.

Matt aligning finder on Apex 127

I brought the Apex 127/SV50 combo – I’m sighting on the moon here, to align the finder with the scope – and the C80ED.

Matt digiscoping moon

Here I am digiscoping the moon with the C80ED. I used the Apex 127 for tracking down some planetary nebulae and double stars, and the C80ED for photography and just messing around. It’s a crazy fun little scope. Unfortunately, none of my moon shots worked out this time.

The forecast called for clear skies most of the night, but clouds between 10:00 PM and 2:00 AM. We got set up before the sun set at 4:45, and pushed through until 10:40. Then it got too hazy to observe, so Terry and I sat and jawed about scopes, atlases, and observing projects until the sky cleared a bit at midnight. We got in about half an hour more before the sky clouded over completely about 12:40. We talked a bit more then turned in.

Jupiter and moons 0530 PST 2015-11-15

I got up at 4:00 AM to catch the morning planets – Jupiter, Mars, and Venus. I cannot get the iPhone to take a fast enough picture to capture any detail on Jupiter – it always comes out as a blank circle of light (with some glare from the iPhone, not the scope). But the moons show up nicely. I really need to get a better camera control app.

Clouds at dawn 2015-11-15

I was clouded out again at 5:15, and Terry and I sat up until 5:45 watching the approaching dawn. Then it started sprinkling! Weather Underground, the Clear Sky Chart, and my other weather app all missed that. We packed up quickly and drove out at 6:30. A hearty breakfast at the Coco’s in Indio put a cap on the expedition. Although the skies were less than perfect, we had a good time catching up, and we did see some nice things.

Waxing gibbous moon 2015-11-22

Back Again

As luck would have it, I was back at the sea just eight nights later. London and I hadn’t been to the Salton Sea since last November, and he has all this week off from school, so we went last night. He took his XT4.5, and I took my C80ED. The waxing gibbous moon was only three days short of full, so the skyglow was pretty bad. But the seeing was excellent, easily 8 or 9 out of 10. I could split the four main stars of Orion’s Trapezium wide open at 25x, and fleetingly at 19x with the 32mm Plossl.

I could have held that split more easily with a better low-power eyepiece. I had not noticed it before last night, but my trusty Orion Sirius 32mm Plossl, my go-to widefield and finder eyepiece for many years, has some astigmatism. Not a lot – it was only noticeable immediately after switching from my 24mm ES 68. I tried both eyepieces with and without eyeglasses to confirm that the aberration was in the Plossl and not elsewhere in the optical train, my eyeballs included (I tried both). Another case of getting spoiled by premium eyepieces. It’s fine, though – since the 24mm ES 68 gives the same field of view, I only pull out the 32mm Plossl when I want to drop the magnification even lower, or when I’m doing outreach.

Sigma Orionis sketch 2015-11-22

I spent a lot of time cruising the central part of Orion at 120x with the 5mm Meade MWA, which is now my preferred high-power eyepiece. Just three weeks ago I saw and sketched the multiple star Sigma Orionis for the first time. It’s funny – I’d been observing Orion regularly for eight years before that and I’d never seen it, but now I stop there every night I have a scope out. Even London’s little 60mm Meade refractor split the six main components wide open. But last night I saw a faint, seventh member that I’d previously missed.

I turned in relatively early, around midnight, figuring that I’d get up after the moon set and do a quick morning Messier hunt. And the sky was truly phenomenal after moonset. I was waking up about once an hour and having a quick look around, and it was a spectacularly clear, dark night. But the flesh was weak, and I overslept, only dragging myself out of my sleeping bag at 5:00. By that time the first glimmerings of dawn were lighting the eastern horizon, so I skipped the Messiers and went to Jupiter.

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That planet above the scope is Venus, not Jupiter.

The view was jaw-dropping. The seeing was rock solid and I was able to Barlow the 5mm MWA up to 240x without the image breaking down. At that magnification I could detect at least three delicate brown belts north of the North Equatorial Belt, and the Galilean moons were little spheres, not just points of light. I tried taking some pictures but didn’t get any better results than I had the last time out, so I put the camera away and just stared. I must have spent 45 minutes just watching Jupiter drift across the field of view, mostly at 240x.

Last night I was definitely in aesthetic observing mode. I spent a little over two and a half hours at the eyepiece, entirely on four objects – the moon, Orion nebula and Trapezium, Sigma Orionis, and Jupiter. I had half-formed plans to look at other things, but I kept getting seduced into long sessions of fully immersed stargazing. And I’d do it again in a heartbeat.

IMG_6369

So, neither night had perfect observing conditions. It was hazy the first night, and the moon was out during the convenient observing hours last night. But I had a great time both nights, saw some cool things, learned a little more about my gear, and enjoyed the good company of Terry and London. Couldn’t really ask for more.

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Crazy sky atlas sale at Sky & Tel

November 23, 2015

Shop at Sky atlas sale

What the heck? My current favorite sky atlas is the interstellarum Deep Sky Atlas – more on that in another post – but the offerings from Sky Publishing are seriously discounted right now. I’m tempted to pick up another copy of the Pocket Sky Atlas just to have one to play with. If you’re interested, go here and do the right thing.

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A truly tiny scope – the Synta MC90

November 18, 2015

MC 90 set up for birding

I realized in conversations with Doug and Terry recently that I have not blogged about the Synta MC90. I got one of these way back in the spring of 2009, on my quest for the perfect travelscope. I only used it for about a month before putting it on semi-permanent loan to my brother Todd. I did briefly mention the scope and show the photo of it set up on the hood of the car in this post.

In the early 2000s it was offered by a variety of vendors – I’ve seen units online labeled Synta, Orion, and Omcon. There’s a review of the scope on Cloudy Nights here, and the same article appears verbatim here.

MC 90 business end

It’s an odd little thing: a 90mm Maksutov Cassegrain, but operating at a fast f/5.6 (500mm focal length) instead of the more typical f/13.9 (1250mm). The most obvious con is that with such a steep light cone, the secondary mirror has to be quite large, which degrades contrast. Pros are that it can get a much larger true field of view than the ~1.3 degrees that the f/13.9 scopes are limited to – I’ll have to check, but unless it’s somehow vignetted it should be able to do over 3 degrees – and that it is incredibly compact.

MC 90 length

It is the same ‘barrel size’ as the longer 90mm Maks, but only about 2/3 as long. Take off the diagonal, eyepiece, and strap-on finder (in this case, a red-dot gizmo from StellarVue) and the scope almost disappears, which has two nice effects. First, just about any mount will be sufficient. In the photo at top I have it mounted on a Manfrotto MKCOMPACTACN-BK tripod and the whole setup weighs only 5.5 lbs (2.5 kg).

C90 orange tube in cooler

Second, if you need a case for this scope, you probably can’t do better than to get a six-pack cooler from Wal-Mart, which will set you back about six bucks. In this photo the scope in the “case” is my old orange-tube Celestron C90, but the MC90 fits inside just as easily. The black drawstring bag holds the finder.

Given how much I’ve written about them in the past, you may fairly wonder where my love for little Maks has gone. Each one got killed by a different problem.

SW 90 on tripod 1

My 90mm SkyWatcher Mak got out-competed by other scopes. The Apex 127 is no more trouble to set up but performs significantly better on just about everything, and if I’m in the mood to roll with a smaller scope, the C80ED has better contrast (as demonstrated in this post), takes magnification about as well, and is more versatile. I still have the little SkyWatcher Mak, mostly because I haven’t gotten around to selling it, but I haven’t used it in well over a year and I don’t imagine that I will miss it.

Happiness is--

From left to right: XT12, XT10, AstroScan, C90, XT6, SV50, 5″ SkyWatcher Newt on homemade dob base. Out of all of these scopes, the only ones I still have are the XT10 and SV50.

I sold the orange-tube C90 a long time ago. I really, really wanted to love that scope. I like the idea of that scope. It’s built like a tank, and since it focuses by rotating the barrel like a giant camera lens, there’s almost nothing that can go wrong with it. If that focus action ever does get sticky, there are instructions online somewhere showing you how to disassemble and regrease it. Basically, as long as our civilization can produce grease, and the scope doesn’t get dropped or left out in the rain, it should never, ever wear out.

BUT that rugged, rotating-tube focuser is also the problem. With such a long focal length, you start at medium powers and go up to high power pretty rapidly. That’s just the natural métier of a long focal length Mak. My problem was that it was almost impossible to focus the scope at high powers without nudging it off-target, and in fact the shakes that were induced by having my hand on the OTA were usually enough to make precise focus a guessing game anyway. It wasn’t a mount problem, it was me needing to paw at the scope to get it to do anything. Don’t know how many other people had the same problem, but I note that for its current, popular, and inexpensive incarnation (still around $160), Celestron has gone to the same rear-mounted focus knob as everyone else.

Synta MC90

Image borrowed from Cloudy Nights.

Finally there’s this MC90. I never really gave it a fair shake back in the day. I only had it about a month before loaning it to my brother, and I’ve only used it on one or two evenings since, neither of them in the last five years. Also, my observing interests have changed. Back in 2009 I did a lot more lunar and planetary observing, and now I’m more interested in DSOs and low-power, widefield scanning, where the MC90 might do better. I’m going to borrow it back this Christmas and give it a serious workout. I’ll let you know how that goes.

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Sunday night on Mount Baldy

November 3, 2015

Moon through trees 2015-11-01

Sunday night I went up Mount Baldy for a solo session. I was rolling with the C80ED, which has become my default grab-n-go rig.

One of my goals was to test a couple of new eyepieces. Several astro retailers had a big sale on Meade wide-angle eyepieces last month. I was torn between the 20mm and the 5mm Series 5000 Mega-Wide 100-degree EPs (man, is that a mouthful or what?). The 20mm would have been a great low-power, widefield scanner, which is something I’ve gotten progressively more interested in this fall. But for a long time I had been without an EP shorter than my 6mm Expanse, which is not without its problems, so I sprung for the 5mm instead.

In the meantime, thanks to this thread on Cloudy Nights I had become aware of the VITE eyepieces. These odd little birds come in only 3 focal lengths (at least so far): 23mm, 10mm, and 4mm. They are three-element EPs with one aspheric plastic element and plastic bodies. They’re about $17 apiece on Amazon, or $9 apiece on eBay. I ventured my nine bucks and got the 4mm from eBay, thinking it would make an interesting comparison with the 5mm Meade 100-degree. I had done a quick comparo late Saturday night from my driveway on the moon and the Orion Nebula – more about that in a bit.

Sunday evening on mount Baldy I cruised through the highlights in Lyra, Cygnus, and Sagitta. I did a quick, rough sketch in my notebook of the open cluster NGC 6823. It has a curl of stars wrapping up around it like a fiddlehead fern.

NGC 6823 sketch

After that a couple of high school kids and their little brother drove up nearby, and I spent about an hour showing them around the sky – the Dumbbell Nebula (M27), the Double Cluster, Pleiades, Andromeda galaxy, Polaris, M15, 61 Cygni (aka Piazzi’s Flying Star), and finally the Messier open clusters in Auriga – M37, M36, and M38.

The kids left about 10:30. Since I was in the area I had a look at M1, and then cruised down to Orion. The constellation was slowly crawling over the ridgeline to the east, so I started visiting the bright stars, and in some cases splitting them. First up was Meissa, which was elongated at 68x and cleanly split at 120x in the 5mm MWA and 150x in the 4mm VITE.

Mintaka was an easy wide split at only 25x. Seeing was not good, but Eta Orionis appeared to be elongated east-west at 120x and 150x. The view in the VITE was kind of a mess, so I spent a few minutes just cruising around Orion’s belt and sword with the 5mm MWA. Alnitak and its dim companion were widely split. I turned south to Sigma Orionis. I’ll have to check my notes, but I don’t believe I’d ever split this star before. It’s pretty great, with a group of three fairly bright stars and a second group of three much dimmer ones. I backed down to 68x and all six stars were still nicely split, and frankly looked a bit sharper, although that might have been down to bad seeing.

Sigma Orionis sketch

So, here are my thoughts and observations on the 6mm Expanse, 5mm MWA, and 4mm VITE. These don’t count as an actual review, as I didn’t have equivalent focal lengths to compare, and I’ve only spent a couple of nights with the two newer eyepieces, observing only a handful of objects. Still, I tried them on a variety of things – the moon, globular and open clusters, the Orion Nebula, double stars – and the strengths and weaknesses were consistent. All of these observations are with the C80ED, so the chromatic aberration (CA) with certain EPs is particularly interesting.

6mm Expanse – Has a small but noticeable amount of CA on bright stars. Eye placement is a bit tricky – I get some kidney-bean and full-aperture blackouts until I get my eye placed just so. Comfortable enough once I get my eye in the zone, though. Halos on some bright objects.

5mm MWA – Sharp from edge to edge. No detectable CA, but the edge of the field does look blue until I get my eye centered. No detectable field curvature. Eye relief is pretty tight – when I move in close enough to see the entire field, my eyelashes brush the lens about half the time (I do have long lashes, but still). I have to move my head around to focus on objects in different parts of the field. Very immersive – I feel like I could climb through the eye lens and into space. The rubber eyecup is annoyingly loose – it frequently comes off with the dust cap.

4mm VITE – Can’t focus the whole field at once. Center of the field is sharp enough, but objects start getting blurry halfway to the edge of the field and are entirely defocused at the edges. ‘Sweet spot’ is pretty small. Considerable CA – makes an ED refractor perform like a short fast achromat! Strong internal reflections from bright objects on the edge of the field, or just out of the field. Almost impossible to focus on the lunar terminator if it’s centered – a big bright glow from the lit side of the moon fills the center of the field. Eye relief is tight – eyelashes scrape most of the time.

Verdict – The 5mm MWA is a keeper. The eye relief is short but tolerable, and totally worth it for the huge, flat, well-corrected field. As for the VITE, I’m glad I didn’t spend more than $9. I’ve read that these perform better in longer focal ratio instruments, but at f/7.5, the C80ED isn’t exactly fast. So how long does the light cone have to be for the VITE to perform well – f/10? f/15? At those focal ratios, it would take an exceptionally still night for a 4mm EP to be useful. I will try the thing in my Mak and probably in my C102 but I am not expecting much. People on CN seem pretty happy with the 23mm, so maybe there’s some variation within the line.

Back to the observing report. By midnight I was tired and my feet were cold. I had just resolved to pack up and head home when I saw that the hillside behind me was lit up by moonlight. The moon was coming up behind the ridgeline to the east. It had been a long time since I’d had a chance to shoot the moon rising behind trees, so I quickly set up the camera adapter and got to work. My best still shot is at the top of this post. And here’s a video:

I went for the sideways aspect ratio this time, but I didn’t quite get the camera square on to the view. Guess I’ll just have to try again next month.