Wednesday, May 29, 2024


Issue 604: Unk’s Yearly M13, The Quest for Simple but Good


Suzie's M13
Summertime, summertime, sum-sum-summertime!
  You know it is here, Muchachos. No, not officially; the Solstice ain’t arrived just yet. BUT… Memorial Day is in the rearview mirror and M13, the Great Globular Cluster in Hercules, is climbing higher night by night.  Even given this fricking-fracking Daylight Savings Time, it is now out of the horizon murk by mid evening and the tail-end of astronomical twilight. So, time for your ol’ Uncle to get after it.

“After what, Unk? Wut you talkin’ ‘bout now? Too much Yell last night? Did you bump your head gettin’ outa bed? What?” Simple, Skeeter:  my yearly quest to image that greatest of all Northern Hemisphere globular star clusters, Messier 13. That is a long-running astronomy ritual with your old Uncle. Like my annual Christmas Eve observation of M42. Weather ‘n stuff conspired to make me miss the Big Glob last annum, and I wasn’t gonna let that happen again this year; I’d get started as soon as possible, like RIGHT AWAY.

The only question was “How would I get M13?”  The last decade, the answer has been “As easily as possible.” Yeah, some years I’d drag out big mount, SCT, computer, and CCD and go whole hog, but those years became fewer as I hit my mid-60s. Mucho fewer. And soon enough, the days of setting up my SBIG CCD on a C11 were gone forever. As the years roll on, and the gear seems to get heavier and the spring and summer nights ever hotter, I've looked for ways to corral ol’ Herc (or whatever) without busting a gut or being a sweat-drenched wreck at the end of the run.

The first Quick and Dirty approach I took to M13 was video, deep sky video. As y’all know, during the years of The Herschel Project, I was all about video. So, it seemed a natural to go after M13 that-a-way. No guiding. I could even use an alt-azimuth mounted scope. The original Stellacam (analog black and white video and <10-second exposures) did a credible job.

The Mallincam Xtreme that followed it was better still with less noise and longer exposures. But while I didn’t have to worry about guide scopes and polar alignments, that was still a load of gear:  scope, mount, camera, cables, monitor, digital video recorder, etc. There was also no denying the results didn’t look that great. Oh, the videos looked pretty good, and the still frames from them were acceptable. But attractive? Not really.  I looked for that much wished-for and sought-after Better Way.

At about this time, quite a few refugees from the analog deep sky video scene began experimenting with a similar imaging mode. This was short-exposure imaging with digital cameras. CCD cams, DSLRs, you name it. The idea was to take a bunch of short—as in 10 - 15 seconds or so—exposures and stack them together in the usual way. I was rather skeptical of the idea, thinking that at a minimum 2 – 3-minute subs were required for a decent image.

However, I had a camera suitable for experimentation—my ZWO ASI 120mc color planetary camera. While I could have used an alt-azimuth scope for my testing, I chose to put the OTA on an equatorial. I figured that would eliminate noise and other trouble from field rotation and would give the short-sub idea its best chance at success.

And away we went. The C8-on-a-GEM setup was a slight pain, but not too bad. Soon my old Ultima 8 OTA, Celeste, was riding on the CG5 with the li’l ZWO cam on the rear cell. Other than that, I had a laptop set up on the deck running the amazingly versatile FireCapture software, which is just as much at home saving single exposure frames of a deep sky object as it is planetary .avi files.

The result? The camera’s chip is a tiny one as is normal with planetary style and guide cameras, but with the C8 reduced to around 700mm it wasn’t bad at all, and suitable for small-medium deep sky objects like M13, or M57 where I began. I could tell from the images coming in that I could stack and process the Ring into something looking pretty nice. Yes, the images were noisy despite the dark frames FireCapture applied, but that was due to the uncooled nature of the camera and warm Possum Swamp spring nights and not any limitations of the short-sub method.

M13? Easy as fallin’ off a log. As you can see in the image here, M13 with the 120mc is considerably better than the inset longer exposure (1-minute subs) of my stacked Meade DSI image from many a Moon ago. I was pleased. But I put the ZWO away and never came back to it for the deep sky. Instead, I took to doing my yearly M13 with an 80mm APO and a DSLR. That was easy to do, but f/6 80mm plus DSLR frame size produced a rather miniscule M13. In retrospect, I could have gotten better images with my ZWO and the little refractor.

That has been the story the last several years. Me using a small, short refractor and a DSLR to do the Great One. Was I satisfied with the images? No. As above, M13 was just too small, and the 80 APO and DSLR were not well-suited for the suburban environment. That’s where my Yearly M13 came to rest for a while, but that was then, ladies and gentlemen. This is now.

What is different now when it comes to taking decent deep sky images easy-peasy? Do I even have to tell you? It is the coming of the smart telescope.  I’ve talked about my little ZWO scope frequently here—I am very fond of her. She's not perfect. Some of the images are better than others, I’ve observed, and it’s not always clear why. Oh, no doubt you could achieve more consistency as far as perfect stars in every shot by downloading individual sub-frames and stacking ‘em yourself. I choose not to do that because I am rather lazy these days and find the stacked .jpgs Suzie delivers to my phone almost always more than acceptable.

Anyhoo, about a week and a half ago, I carried Suze into the backyard. Yes, it was a little early in M13 season and the glob was still a bit low mid-evening, but this is Possum Swamp we are talkin’ about. It can easily be cloudy for weeks and weeks. Easily. Plus, I had already decided M13 would be the subject of this installment of the blog (in part to impel me to get out of the air conditioning and get a few snapshots, at least). Out into the back 40 we went. One look at the sky told me I’d be lucky to get anything, and that our time under the stars would be limited.  Oh, and at 8pm it wasn’t anywhere close to being dark enough to shoot anything. I might, might be able to begin shooting at nine o’clock. 

When I thought it was dark enough to begin, I trotted out, turned Suze on, connected to her with the iPhone, and used the manual altitude slewing buttons (a recent addition to the app) to raise the girl’s little OTA out of parked position. The reason for that was so I could install a dew shield I’d purchased. Not because of dew, though. The scope’s built-in dew heater has always kept that at bay, but I wanted to block some of the ambient light that inevitably intrudes into a suburban backyard. I thought images would look better with minimal processing without the gradients the neighbors’ yard lights inevitably cause.

Which dew shield? Where do you get such a thing for the SeeStar? Take a stroll through the eBay. You’ll find a surprising number of sellers offering dew shields and other plastic 3D-printed SeeStar accessories. I got mine from an outfit called “West Coast Astro.” On the plus side, it is reasonably attractive and works fine. On the minus side? I couldn’t use it the first night after I received it; it wouldn’t fit the SeeStar. I had to do some sanding of the barrel. Not a lot, just a little and then it was fine. On the plus side again? The seller included a bag of Haribo gummies in the box—just like Adrian of Adrian’s Digital Basement often receives in his Mail Call packages… so I was placated.

Me turning on the Suze, connecting to her with iPhone, and installing the dew shield was the extent of my night under the stars. How do I feel about that? I’m not sure. There is certainly something to be said about a calm and peaceful night under the shimmering stars of spring. Instead, I spent the balance of the evening on the couch in the den with Tommy, Chaos Manor South’s resident black cat, watching the aforementioned Adrian’s Digital Basement to the accompaniment of cold 807s (me) and ‘nip (Tom). It was relaxing, yeah, but decidedly lacking that “romance of an evening under the stars.”

On the other hand…  An imaging run done the conventional way is usually spent staring at a laptop screen rather than the stars. What I shoulda done, I guess, was grab the Burgess 16x70 binoculars and do a little bino tour while Suzie did her thing. Next time, perhaps. And I will admit that even purely visual observing ain’t always a picnic. Heat. Bugs. More heat. Dew. Sweat. And, when I was a young’un, the sneaking suspicion THE VISITORS might pounce on me as I stared into my Ramsden. In other words, some, not all, but some, spring/summer visual observing runs are better to relive in fond memory than to experience.

Anyway, next up for this here blog will be some visual. FINALLY, and about time, I reckon. “Wait Unk, what about the pitchers?!” Not too much to say about them. As you can see, Suze did fine, hell, you can even pick out little and dim IC 4617. I’d say her results were better, at least somewhat, than those the ZWO planet-cam produced with an SCT. They are certainly preferable to the eensy-weensy M13s that came out of the 80mm/DSLR combo. So ended the evening of My Yearly M13. With more success, I think, than it has in quite a while.


This past week I got Suzie out for a longer go at the Bigun. 15 minutes does produce decent images with the SeeStar but doubling that to 30 minutes makes the shots look a little smoother and more finished. Half an hour is what I aim for when I am granted clear skies for that long. When M13 was done, I shot M92, too, which also looked right nice.

Before shutting down, I devoted a couple of minutes to The Turtle, NGC 6210. As I’d feared, it was pretty small in a 50mm f/5, so I cut things short and shut ‘er down. In retrospect, I should have given Suzie more time on the nebula. It’s possible that in a longer exposure, I could have picked up a trace of the two ansae, the nebulous extensions on either side of the disk. I didn’t, so all I got was a little green ball. Next time, maybe.

And that, muchachos, is one of the things that has kept me in this business nearly 60 years down the line. There is always that Next Night to look forward to...





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