Archive for the ‘Double stars’ Category


Binocular double stars in Draco: my article in the August 2017 Sky & Telescope

July 6, 2017

This one came about by accident. In February, 2016, I went down to Borrego Springs, California, to give a talk at the Western Association of Vertebrate Paleontologists annual meeting. After the conference, I went up to camp for the night at Culp Valley Campground in Anza-Borrego Desert State Park. Anza-Borrego is a dark place to start with, and Culp Valley is up around 3500 feet and even farther from any towns or buildings, so it is stupid dark up there.

I got almost all the way around the sky with my binos that night, both in the early evening and then again before dawn. I was struck by how many nice binocular double stars there were in Draco. At first I was thinking I might use 3 or 4 of the best as the basis for a Binocular Highlight column, but pretty soon I was up to a dozen and I realized that I had enough ammo for an observing feature. I went back out this spring with a whole range of binoculars, up to and including mounted 15x70s, to re-observe and take notes. There are 20 doubles listed in the article, and although a few of them will require big binos to split cleanly, most can be split with 10×50 or even 7×35 binoculars, and a couple can probably be split with naked eyes if your vision is good.

If you want even more, or if you want to get a taste before you spring for a copy of the magazine, I also wrote an online feature with several more doubles that didn’t make the cut for the printed article. You can find that online feature here.

I’ve written for Sky & Tel on the Milky Way (twice), galaxies, and look-back time, and I’ve included individual double stars in Bino Highlight columns, but this is my first feature on double stars. What worked, what didn’t, what would you like to see in the future? The comment thread is open – I’ll look forward to hearing from you.


Marking up sky atlases

February 4, 2017

I’m a book lover. Any space I’m in for long will have books on every available surface and piles of extras on the floor. Because of this love of books, for a long time I wouldn’t mark them up. This hands-off reverence extended to my sky atlases. But eventually I realized that sky atlases are tools, not heirloom pieces, and anything that makes them more useful when I’m observing is justified.


Here’s a representative page from my working copy of the Pocket Sky Atlas (I also have a second copy, autographed by John Dobson, that actually is an heirloom piece now). The circles and polygons flag objects from various Astronomical League observing projects. Triangles are double and multiple stars, rectangles are Herschel 400 objects, big circles are for the Binocular Deep Sky objects, and an open letter C designates Caldwell objects. I also drew in the position of Almach, which is just off the edge of this chart, wrote in the number for the multiple star 57 Persei, and wrote down the magnitudes of Algol and some of the useful reference stars, including Almach. Arrows in the margins are left over from my Caldwell tour.

I’ve finished all of those projects except the Herschel 400. You’ll see that some of the little rectangles have a diagonal slash across one corner – that’s how I flag which ones I’ve already observed. I’ve actually seen all of the H400s on this chart, I just got lazy about marking them off in the atlas. But I did write ‘CLEAR’ in the corner of the page so I know not to waste my time looking for unobserved H400s here. Other pages have the numbers of the H400s I still need written in the margins, for quick sorting and bookkeeping at the eyepiece.

These marks are very helpful while I am working on a project, because I have an instant visual reminder of what’s available to see in any given stretch of sky. And once I’m done with a particular project, the marks still point me to a lot of ‘best in class’ objects that I might otherwise overlook or forget.

Oh, I also sketch in the positions of comets from time to time, with the dates of observation.

This method has worked so well for me that I have thought about picking up extra copies of the PSA (for $13!) just so I could mark them up with objects from other observing projects. I’ve done that with a couple of my other atlases. My copy of the Cambridge Double Star Atlas has all of the AL Binocular Double Star targets marked, and I use my Jumbo PSA (which is ridiculously useful) to keep track of targets from the last several years of Sky & Telescope’s Binocular Highlight column, to help me avoid repeats. Of course I have other lists for all of these things, both physical and digital, but it’s nice to have an easy reminder when I am out observing or doing desk research.

Do you mark up your atlases? If so, what system do you use? Let me know in the comments.


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.


My article in the December Sky & Telescope

October 31, 2015
SnT Dec 2015 cover - marked up

Einstein has my article on his mind!

Here’s the exciting news I teased back in September: the December 2015 issue of Sky & Telescope, which is available online and should be hitting newsstands about now, has an observing article by yours truly. It’s a binocular tour of the southern stretch of the winter Milky Way, from Canis Major through Puppis to end in Hydra.

SnT Dec 2015 contents - marked up

The road that led here started back in December, 2014, when I got a very nice email from S. Johnson-Roehr, “JR”, the observing editor for Sky & Tel. JR had stumbled across this very site (possibly because I’d just recommended the newly-reprinted Caldwell Objects?) and asked if I’d be interested in contributing an observing article. We batted some ideas back and forth and quickly settled on the winter Milky Way. I had been through this area of the sky before but I wanted to give it one more pass, both to flesh out my notes and to road-test the star hops I had in mind. I made those observations this spring, wrote the article over the summer, and now it’s out in the world.

I have one favor to beg of anyone who reads the article – I need feedback. This is my first time writing about astronomy anywhere but a blog, forum post, or club newsletter, and I’d like to know (1) what worked, (2) what didn’t, and (3) what you’d like to see in the future. The comment field is open.

There’s a lot more to like in this issue of S&T, some of which will be of particular interest to regular readers of this blog. Tony Flanders has another inexpensive telescope shoot-out. Back in 2011 he and Joshua Roth looked at $100 scopes, in particular the Orion SpaceProbe 3, GoScope 80, and SkyScanner 100 (that article is a free download here, and a follow-up comparing the SkyScanner to the StarBlast is here). This time Tony considers three scopes in the $200 range: the Meade Infinity 90mm refractor and alt-az mount, the Orion StarBlast 4.5, and the Astronomers Without Borders OneSky. I won’t give away any spoilers, except to note that he finds all three to be capable scopes, which I’m sure is no surprise around here.

Another nice review in this issue is Alan MacRobert’s look at the first two volumes of Jeff Kanipe’s and Dennis Webb’s Annals of the Deep Sky, from Willmann Bell. As a deep-sky junkie who likes to read himself to sleep with Burnham’s Celestial Handbook and Stephen James O’Meara, I have been curious about these new books, but I hadn’t heard anything about their quality before reading MacRobert’s article. Sounds like I need to make space on my Christmas list.

There’s loads more interesting stuff in this issue – cover articles on Einstein and gravitational waves, great observing articles by Alan MacRobert, Fred Schaaf, Gary Seronik, and Charles A. Wood, a very nice piece by Sue French looking at some neglected open clusters and double stars in Cassiopeia (an area I thought I knew well)…you get the picture. If you’re not a subscriber, you can find the December issue of Sky & Telescope on your local newsstand, or order a print or digital copy online here.

If you’re new here, welcome! Have a look around, and feel free to comment.


Double stars and the Double Cluster: a short observing run in bright skies

October 17, 2015

I completed a major lecture Thursday so I treated myself a short stargazing run in the driveway that evening. Transparency was rotten – it was so humid here that even with the temps in the low 70s I was still sweating, and with all that water vapor to bounce back the city lights, the sky was bright to about 45 degrees above the horizon. I did a quick turn around the sky with my old 7×35 binoculars, which I’d not used in ages, and all I could see were the major constellation outline stars. I decided to see what the C80ED could do, in part because it’s my best grab-n-go scope and I knew it would be a short run, and in part since I’d just had it out under much darker skies.

I started on M57, the Ring Nebula, which is obvious even at low power under most conditions. This time out, the Ring was just a ghostly blob in averted vision at any magnification, even when Lyra was still quite high. But the seeing was rock-steady. Epsilon Lyrae, the famous double-double star in Lyra, was very elongated, like a pair of 8s, at 68x, and cleanly split – juuuuust barely – at 100x, although I had to go up 136x to easily hold the split in direct vision. After that I bopped over to Cassiopeia/Perseus to split some doubles (Eta Cass was nice) and look at the Double Cluster. Didn’t attempt a sketch, I was just rolling for aesthetic appreciation, but I did use a lot of magnification and spent more time on the clusters than I usually do. I had not noticed before that NGC 884 has an empty center. I mean, under dark skies there are plenty of stars in the middle, but the bright stars form a series of arcs around the edge, and under so-so skies those outer bounding arcs of stars are all you can see. NGC 869 is the opposite, it just gets more and more concentrated toward the center, albeit unevenly.

Double Cluster from SEDS

The Double Cluster: NGC 884 (left) and 869 (right). Photo borrowed from SEDS.

At 11:20 the clouds suddenly thickened up – in the space of five minutes I went from pleasant observing to totally socked in. After I got everything stowed, I went inside and looked up Stephen O’Meara’s entry on the Double Cluster in his Caldwell Objects book. His observations were gratifyingly similar to mine, but I learned some interesting stuff about the clusters. They are BIG and they are distant: 7300 light years, compared to less than 4000 light years for most Messier open clusters, and dimmed by about 1.5 magnitudes by intervening dust clouds. One shudders to think about how much more impressive they’d be if they were only half as far off and not obscured by interstellar dust.

Anyway, a good run. We’re clouded out this weekend, so I’m glad I got it in.


Comet PanSTARRS, and other targets of opportunity

March 13, 2013

I had a short but very fun stargazing session tonight. I went to the top of the parking garage in downtown Claremont to look for Comet PanSTARRS. I knew that it would be horizonwards and a little right of the moon. I took the Apex 127/SV50 combo and my 15×70 binoculars. I got set up a little after 7:15 PM and started scanning the western sky, using the 15x70s and SV50 in alternation.

At 7:25 I spotted the comet in binoculars. It was down in the bright twilight glow, but it was surprisingly bright itself. Like a lot of things that you spot just as they’re coming out in the evening, once I’d found it I thought, “Dang, that’s bright, how did I miss it before now?”

Binoculars are pretty much guaranteed to be the best instrument for first picking up the comet, but it is big and bright enough to be a very rewarding telescopic target, and if you only see it in binoculars, you will definitely be missing out. Here’s a little trick for getting it in the scope: once you have it in the binoculars, scan straight down to the horizon–which ain’t far–and find a landmark. Go back up and relocate the comet, then back down again to make sure you’ve got the right landmark (I didn’t, the first time–I’d let the bins drift too much to the right on the way down). Anyway, once you’ve got the landmark, you’re golden: point the scope at the landmark and scan up to find the comet.

At 64x in the Apex 127, the nucleus seemed to be an extended object, not just a point of light. The tail swept straight up. I thought it was a little brighter and a little crisper on the north (right side in the sky, but left side in the scope). I wish I had sketched it–I’ll do that next time out.

Just a few minutes after I got the comet in my sights, a young couple pulled up and parked nearby, and invited them over to see the comet and the thin crescent moon. When the young woman saw the moon in the scope, she jerked back from the eyepiece, shook her hands, and said that the view had given her the chills. When people ask why I do sidewalk astronomy, I tell them about things like that.

Later on a family of five pulled up and I showed all of them the comet and the moon. So I had an astronomy outreach to a total of seven guests tonight. My favorite part: helping a 6-year-old kid get the 15x70s balanced on the side rail of the parking garage so he could see the moon.

If you’d like to see the comet, your best chances are in the next week or two. It will probably be bright enough to see with a telescope for weeks after that, maybe even months, but it isn’t going to get any brighter. Get over to Sky&Tel or just google “comet PanSTARRS”–the internet is falling over itself giving out instructions on how to find the comet right now.

By 7:50 all my visitors had moved on and so had the comet, lost in the hazy clouds over Los Angeles. I wasn’t done, though.

Urban decay

As I’m sure I’ve mentioned here before, I’m closing in on finishing two of the Astronomical League’s observing programs, the Urban Observing Club and the Double Star Club. If I’d gotten my rear in gear a month ago I could have finished them both easily by now, but my head was stuck in the Jurassic and I let too much time slip by. As of a couple of days ago, I only needed two more objects for each club: M77 and Algol for the Urban Club, and Alpha Piscium and 8 Lacertae for the Double Star Club. The trouble is, they’re all low in the western sky now, and in a month or  two they’ll be right behind the sun. So if I don’t get them pronto, I’ll have to wait a while before I’ll get another crack at them.

I got M77 Monday night from my driveway. I’d also seen it Saturday night on my Messier Marathon, of course, but that didn’t count; to be eligible for the Urban Club, the observations  have to made from someplace sufficiently light-polluted that the Milky Way is not naked-eye visible. Fortunately this galaxy has a crazy-bright core and I caught it with averted vision from the driveway even though it wasn’t fully dark yet. My time limit was set less by the sky and more by local geography: when I saw it, it was already in between the leafless branches of one of the trees in my back yard.

Algol is up in Perseus, still a good 25 or 30 degrees above the horizon at sunset, so it’s easy enough to see. That ain’t the problem. It’s the only variable star on the Urban Observing list, so I reckon I haven’t fulfilled the spirit of the thing until I’ve seen it go through one of its periodic brightness variations. These happen about every three days, which sounds great, except that they’re offset so most of them happen during the day, or when the constellation has already set. I need one of those minima to hit between about 7:00 and 9:00 PM, which is a pretty darned narrow window (why oh why didn’t I just see this thing a month ago?). I just missed one on March 7, when my head was still only in the Jurassic. The next one that is in my time window is on the evening of March 27, when I’m scheduled to be on an airplane between Texas and SoCal. The next good one after that isn’t until April 16. That one may just be doable–Perseus is far enough north that it sets pretty late from my latitude (from 40 degrees and points farther north, it doesn’t set at all).

Doing the splits can be painful

I have been kicking and kicking myself for not getting Alpha Piscium and 8 Lacertae in the past few months when they were dead overhead. I actually got Alpha Piscium in they eyepiece one night a week or two ago, but I couldn’t split it before it got lost in the trees. I found out why tonight: it’s a darned hard split.

After the comet and all my visitors had departed, I went straight to Alpha Piscium. It was already down into the near-horizon murk, which makes stars take on interesting shapes and colors that often have nothing to do with their normal night-sky appearances. At 64x it was just a dot. Same thing at 128x. Same thing at 257x, at least at first glance. But then the seeing steadied for a crucial moment and I was able to get the focus dialed in, and there it was: a double star. At high magnification in the Mak, each star is  surrounded by a neat little diffraction ring. At 257x, Alpha Piscium’s secondary component was sitting on the diffraction ring of the brighter primary, as if the primary  was sitting in the middle of a diamond ring. Like this, only I couldn’t see the diffraction ring around the secondary star so clearly. Anyway, it was a pretty sight and a righteous split.

That left me in the same place in the Double Star Club that I am in the Urban Club: 99 down, one to go. I thought that 8 Lacertae might just be possible, so I started star-hopping over that way. I almost got there, too, but just in time to see the lizard’s tail dip below the local horizon. I am pretty sure that if I try again in the next couple of nights, and go to 8 Lacertae before I  do anything else, I’ll be able to get it. It’s a nice wide multiple star, so it shouldn’t be a tough split, if I can just get on target before it sets.

Sunset birding

Another crazy good scope deal

Finally, I’d be remiss if I didn’t point this out: Orion has put their 20×50 compact spotting scope on clearance for $29.99. You can get it through the Orion site or this Amazon link. I am familiar with this scope–London and I gave it a test drive at the Orion store in Watsonville last summer, and on the strength of that encounter London asked for and received one for his birthday last November. We’ve had it out to the Salton Sea a couple of times now, so we’ve gotten to use it for daytime spotting and out under the stars.

How does it do? Well, it’s a 50mm spotting scope, and like most such devices, it basically is a finderscope and has no other finder or provision for one. Also, you’re stuck at 20x. So for nighttime use, you’re going to get binocular-esque views of the moon, planets, and a handful of the brighter DSOs (think Pleiades, Orion, Andromeda) and that’s about it. Also, it’s a short, fast refractor, so there is some false color on bright objects. To be fair, though, almost all spotting scopes are short, fast refractors (‘cept for the Maks), and other than the ED models that cost hundreds to thousands, they all show chromatic aberration. Even my beloved SV50 throws up some false color, and I don’t think the Orion spotter is noticeably worse in this regard.

Going handheld

It’s much more rewarding to use during the daytime. I don’t know why Orion is closing them out, but it probably isn’t image quality, because the two I’ve looked through have been nice and sharp. In addition to the zippered soft-side storage case, the scope comes with a velcro-tabbed, padded fabric wrap-around, similar to the weather-resistant ‘view-through’ cases on some high-end spotters (but offering less than total coverage). This has a padded hand-strap so you can take the scope off a tripod (not included, nor would you want any tripod they could include at this price point–trust me) and use it handheld. This is surprisingly effective, and London and I have taken to carrying his scope along on our morning hikes when we’re camping.

Any downsides, aside from the aforementioned false color? The helical focuser was a little stiff for the first few uses. The usual solution with sticky focusers is to twist them all the way in and out a few times to get the lubricant evenly distributed over all the surfaces. I did that with London’s spotting scope and sure enough, the problem went away. Focusing is a breeze now.


Raw, unmodified photo of some gulls at about 50 yards, taken afocally through the Orion 20×50 compact spotting scope using my Nikon Coolpix 4500.

So, long story short, I dunno why Orion is closing these out, because I think they’re fine little scopes. I haven’t noticed any lasting problems in several days and nights of field use, and if I didn’t already have a 50mm scope of my own, I’d be all over this. It’s a decent buy at $50 and a steal at $30. If you need a small spotting scope, period, or something to keep in the car for impromptu scenery- or wildlife-watching sessions, or something for that kid you know who is interested in nature and science, this thing ought to fill the bill. I’m tempted to get another one myself, to keep in the storage compartment under the back seat of the Mazda. But if you’re interested, don’t tarry–Orion is already out of the spotting-scope-plus-tripod packages, and I don’t imagine the scopes themselves will last long at this price.


Double star marathon?

February 20, 2012

An invaluable aid to me when I am working on an observing program is an all-sky map showing the distribution of the things I’m trying to find. The maps of the Messier objects and Caldwell objects from Wikipedia are my constant companions when observing: I printed them in color on 11×17 paper, folded them in half, and stuffed them in sheet protectors.

When I started on the Astronomical League’s Double Star list there was no similar all-sky chart for the 100 double and multiple stars on the list,  so I made one, using the Wikipedia Messier sky chart as the basis:

When I had them all mapped, I noticed that by and large they follow the distribution of the Messier objects, especially in having a big gap to the south between 22 hours and 5 hours right ascension–just the area blocked by the sun and horizons in March and April. I fired up Stellarium and drew on the sunset and sunrise horizons for southern California around the end of March:

Only one of the 100 double stars on the AL list is below the horizon at that time. So during Messier Marathon season it should be possible to do a double star marathon as well, and try to split 99 of the 100 AL doubles in one night.

A double star marathon would bring interesting opportunities and challenges. With Messier marathons, the primary enemy is the moon: you have to go within a very few days on either side of the new moon, or the moonlight will drown out some of the fainter objects. But the relatively bright double stars on the AL list would punch through a fair amount of moonlight. You still wouldn’t want to go between first quarter and last quarter, probably, or the moonlight would wash out some of the guide stars you’d need to find your way, but the window of opportunity should open from six or seven days around new moon to about two weeks.

On the flip side, in a Messier marathon the seeing isn’t that crucial because you’re observing big, extended objects, and just trying to log them, not necessarily tease out details. But to split some of the tighter double stars requires reasonably good seeing, and there’s no way to predict that in advance, sometimes not even from early evening to midnight or midnight to dawn. So the Messier marathon has a tighter constraint from the moon, but it’s predictable, whereas the one sky condition that could make or break a double star marathon (at least for a crucial few of the tightest doubles) can’t be predicted in advance.

I first raised the possibility of a double star marathon a couple of years ago on Cloudy Nights. As far as I know, no one has attempted one. I haven’t, for a couple of reasons. First, if I get to a dark site at Messier marathon time and can afford to stay up all night, I’m going to run a Messier marathon. Second, it’s precisely because double stars punch through light pollution so well that I tend to save them for observing from home–no need to waste my dark sky time on something I can see from my driveway, and my driveway does not have good enough horizons to attempt a marathon of any kind. But I suppose I could head up to the top of the local parking garage and try a double star marathon from there. It wouldn’t require a long drive to dark skies, just a free night followed by a day with few responsibilities.

If I ever get around to it, I’ll let you know.

Related: my free logbook for the AL Double Star Club is on this page, and I have a bunch of Messier Marathon tools here.