Archive for the ‘Bresser AR102S’ Category

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Deep in the Dark of Texas: the Three Rivers Foundation Messier Marathon

March 28, 2017

This story starts with Jeff Barton, Director of Astronomy at the Three Rivers Foundation for the Arts and Sciences (3RF). Jeff sent me a Facebook message on January 27, inviting me to come speak at the 3RF Messier Marathon star party, for which 3RF would pay my travel expenses and provide food and lodging.

I did not get this message until February 19, because I suck at Facebook. Fortunately the offer was still open. So last Thursday I flew to DFW, rented a car, and drove out to the Comanche Springs Astronomy Campus, a little west of Crowell, Texas.

3RF is an educational foundation and Comanche Springs is the North American astronomy wing (they also have scopes in Australia for public education and outreach). It’s out in rural Texas ranchland, and as you drive up the first thing your eyes will light on is the big silver observatory dome.


Inside the dome is a 15″ refractor with DGM optics, an OMI tube, and a monster Astro-Physics mount.


There are several roll-off roof observatories on the campus, with more to come in the near future. This one holds two imaging scopes, a big Ritchey-Chretien on the left and a big SCT on the right, both on Software Bisque Paramounts. These are set up for remote observing – in the near future, schoolteachers will be able to tie into these telescopes and collect images with their students.

Irritatingly, I didn’t get any pictures of the big roll-off roof observatory which holds one of 3RF’s 30″ Obsession dobs, and where they park the two 20″ and one 18″ Obsessions when they’re not in use. That’s right, four 18″ and larger Obsessions in one place. They have more stored in town, waiting for more observatories to be built, and another gaggle of Obsessions in Australia.


In lieu of a picture of the Obsession shed, here’s a view of the north end of campus, looking east. From left to right you can see one of the four or so bunkhouses in the background, the ‘new’ classroom/mess hall, the equipment shed where the binocular chairs are stored, and the restrooms, and one of the observing fields in the foreground.


Here’s one of the motorized binocular chairs. You sit in the padded seat and drive yourself in altitude and azimuth with the joystick on the right armrest, while the Fujinon 25×150 binoculars deliver 6″ of unobstructed light-gathering to each eye. There’s another chair with a more modest but still impressive 100mm bino, and I believe a third chair that wasn’t out during my visit.

The tagline “Deep in the dark of Texas” is not my original, I got it from the back of a 3RF t-shirt. It’s true. The skies at Comanche Springs are dark. Seriously dark. You drive through a section of open range to get there. I had to get a picture of this brown cow sitting by the side of the road – this cow refused to be fazed by anything. I grew up in rural Oklahoma and in my experience, free-range cattle are highly correlated with dark skies. The skies at Comanche Springs are Bortle 1 or 2. The only places I have been under skies this dark are Afton Canyon, the All-Arizona Star Party, and the remote desert of southern Utah. More than 200 miles west of the DFW metroplex, and 20 miles from the nearest town of more than 1000 people, there are no light domes on the horizon – none.

I roomed with these fine gentlemen. You may know Robert Reeves from his several books on astrophotography (see this page) and from his “365 Days of the Moon” on Facebook, which has now been running for more than two years. David Moody is a Fellow of the Royal Astronomical Society (yes, the one in London, co-founded by Herschel) and one of the authors of Astronomical Sketching: A Step-by-Step Introduction. Lonnie Wege is a sales manager at Celestron and brought the door prizes, which were donated by Celestron.

To be in the company of such experienced observers and imagers was a real privilege, but it was only intimidating for the first 30 seconds or so because they’re all so nice. In Seeing in the Dark, Timothy Ferris describes hanging out at the Winter Star Party: “I listened to the elders talk – a mix of astronomical expertise and self-deprecatory wit, the antithesis of pomp.”  That’s what it was like for me at the 3RF star party – just a bunch of regular folks, all equally willing to share and learn, all equally excited for nightfall.

I got in Thursday evening but didn’t do much observing. It was cold and windy, and then cloudy. I did spend a few minutes out in the lee of one of the bunkhouses cruising the sky with binoculars, and I figured out an easy hack for hanging my red headlamp over my bunkbed, but that was about it. Incidentally, my headlamp is already red, but like almost all red-light accessories marketed toward amateur astronomers, it’s still too darned bright. Usually I have a layer of masking tape over the front to knock down the brightness, but for some reason I pulled it off recently. Fortunately they had plenty of red taillight tape in the 3RF coffers, so I got it back into fighting trim.

On Friday I visited the elementary and middle schools in nearby Quanah, Texas, with 3RF’s Director of Education, Townly Thomas. Townly visits schools in a 100-mile radius from Quanah to bring enhanced STEAM (Science, Technology, Engineering, Arts, and Math) activities to kids. I know she’s popular because I heard one student call to her as we walked down the hall: “Mrs. Thomas, when do we get to do STEAM again?” I went in my capacity as professional paleontologist and brought some fossil casts for the students to see. Pictured above are the thumb claw of Saurophaganax, a big allosauroid from Black Mesa in the Oklahoma panhandle (more about that here), and the skull of Aquilops, a little ancestral horned dinosaur that I got to help name in 2014 (ditto). Many thanks to my friends and colleagues at the Sam Noble Oklahoma Museum of Natural History for making the casts available – I’ve had fun introducing them to lots of schoolkids.

After the school visit, I got on the road back to Comanche Springs – I didn’t want to miss the talk by Robert Reeves on his lunar imaging. Here’s a  handful of the many things I learned from Robert:

  • He uses a 180mm SkyWatcher Mak to get his moon images these days. Runs his camera at 50 frames a second for 100 seconds to get 5000 frames, stacks and saves only the best 500, and then does a LOT of careful, thoughtful processing.
  • Lunar shadows are jet black, not gray. If you see gray shadows in someone’s moon images, they need more processing.
  • The lunar Bay of Rainbows is Sinus Iridum, not Sinus Iridium – no third ‘i’. I have been misspelling and mispronouncing it for a decade.

Now, this was a Messier Marathon star party and there were rules and checklists and everything – more on that later in the post. I think that originally Friday, Saturday, and Sunday nights were all fair game for the contest, but Friday night turned out to be suboptimal. We did get a lovely sunset, as you can see above, but those clouds were pushed on through by a strong, cold wind. Instead of setting up scopes ourselves, many of us retreated inside the dome to observe with the 15″ refractor. We also had a group of 15 or 20 college students visiting, so we all took turns looking through the big refractor. They’d already been going for a while when I got inside. The first object I saw myself through the big scope was the globular cluster M3. Then we looked at M51, the Whirlpool Galaxy, and then Comet 41P.

I haven’t blogged about the comet yet, but it is easily visible in binoculars under dark skies, and with any luck it may get naked-eye visible in the next week or so. I haven’t checked to see if it’s visible from Claremont – I was too pooped after I got home last night. I saw it every night in Texas, but I haven’t sketched it yet. Hopefully I’ll get that done soon. In the meantime, Sky & Tel has a good finder chart that will carry you through the end of April here.

After the comet, we looked at the galaxies M102, M82, and M104, and the globular cluster M13. I might have missed an object or two – I popped outside to call home, and spent some time in the attached classroom warming up and getting to know some of my fellow stargazers. I know we went to Jupiter at some point, and we back to Jupiter at the end of the session to catch the start of an Io shadow transit.

I slept in on Saturday and did some final tinkering on my talk. David Moody gave a talk before dinner about visiting the Royal Astronomical Society library and getting to see first editions of books by Copernicus, Newton, Bode, Bayer, and more.

After David’s talk we had dinner and door prizes in the mess hall. Here Jeff Barton (right) is pointing past Fred Koch, who was drawing names, to accuse Lonnie Wege (left) of something. It was all in good fun and there was plenty of laughter, especially when Phil Jones won the grand prize – 15×70 SkyMasters, just like mine – in absentia, having been out setting up his imaging gear. When he came in, Lonnie told him that all he had won was the case, and the binos were going to someone else. Well, binos did go to someone else (whose name unfortunately escapes me), but he had already won 10×50 binos so he kindly donated the 15x70s to Phil. This is Phillip L. Jones of VisualUniverse.org, by the way – you’ve probably seen his photos in books and magazines.

I won a door prize myself – a rechargeable hand warmer. I ran over and plugged it in after dinner so it would be ready to go by marathon time. I was very glad to have it later on.

Saturday night was looking much, much better. There were a few clouds low on the western horizon, but everyone who had come to Comanche Springs to observe or image was getting ready. Here are Glenn Winn in the foreground setting up his 17.5″ Discovery dob, and Jim Admire in the background with his XT10g. Just out of the frame on the right was Jay Ellis and his own XT10.

I set up just south of Jay, and the four of us were the biggest group of visual marathoners. Phil Jones had his imaging rigs set up about 100 feet south of Glenn. There were more imagers on the south observing field, by the Obsession shed, and at least two serious visual observers: Tom Monahan and Russ Boatright (there may have been more, but Tom and Russ are the two who came to the awards ceremony on Monday).

I don’t remember what scope Tom was rolling with, but Russ impressed the hell out of all of us by going super-minimal: he did a naked Messier Marathon from Memory. Not naked as in unclothed, but naked as in, not even with a list of the objects. In a regular M-cubed the observer is allowed no charts – they have to find all of the objects from memory, hence the name. In a naked M-cubed, the observers is not even allowed a list to remind them what to look for, it’s just them and their instrument. Russ ran his naked M-cubed with Canon 18×50 image-stabilized binoculars.

Saturday night’s marathon was great. There were clouds low in the west again, and none of us got M74. But the clouds blew through quickly and after that it was clear, dark skies all night. I was rolling with the Bresser AR102S Comet Edition and Fujinon 7x50s I had borrowed from 3RF. I’d actually flown in with my own binoculars, the Bushnell 10x42s that I had out at Santa Cruz Island last June, but the 7x50s gave a wider, brighter image and were more in line with my current fascination for low-power, wide-field uber alles. I would have brought the Bresser 7x50s that came with the Comet Edition package, but I ran out of room in my backpack – the Bushnell roofs take up about half the space.

And speaking of space in my backpack – I managed to fly with carry-on luggage only. A red duffel bag held the Bresser OTA, Manfrotto tripod, DwarfStar alt-az head, and big dinosaur claw, with my clothes wrapped around everything as packing material. My backpack had a couple more shirts, my laptop, travel paperwork, notebook, Pocket Sky Atlas, binoculars, boxed Aquilops skull, shaving bag, and Bob King’s new book Night Sky With the Naked Eye, which I’d gotten specifically to read on the plane (expect a review soon). Both bags were stuffed nearly to bursting, but they were both within carry-on allowances and the backpack still fit under the seat in front of me.

Oh – rules. There were five categories: Young Astronomer, GoTo Telescope, Non-GoTo Telescope, Binoculars, and Highest Aggregate Score. No-one has ever gotten all 110 objects in one night at a 3RF marathon, so the highest aggregate goes to the person who gets the most over the course of two nights. If there’s a tie in the number of Messier objects, the bonus points kick in. Herschel 400 objects were worth two points apiece, and there was an ascending scale of more difficult dim objects, including Hickson Compact Groups of galaxies.

Here’s my log from Saturday night. Although I missed M74, I tried to make up for it by nailing as many H400 clusters in Cassiopeia and Perseus as I could. By the time I took my first break at 10:15, I had 27 Messiers and 16 H400s. I took several short breaks over the course of the evening to get snacks and caffeine and chat with people. It all went pretty smoothly until just before dawn, when I was trying to catch M30. I star-hopped down from Deneb Algedi (aka Delta Capricorni) to the right vicinity and found myself looking at trees. They were only small trees, and probably 200 yards from the observing field, but they still obscured those last few crucial degrees above the horizon. I’d picked a bad spot.

What I should have done is pick up the binoculars and walk south until I could see the target star with no trees in the way. What I actually did was pick up the scope and chair and run south and set up where I thought I’d be in the clear, only to star-hop down again and see other, different trees – I’d gone too far south. So I moved everything yet again, and by the time I got on target, the sky was getting bright. Fooey. Still, I got 108 objects, tying my personal best from 2013, which was actually the last time I’d even attempted a Messier marathon, so I couldn’t be too unhappy.

As it happened, I tied with Glenn Winn that night. He’d missed M77 in the early evening, but gotten M30, so his list of 108 objects was slightly different than mine but came to the same total.

Anyway, I went to bed happy. Got up for lunch on Sunday, then slept some more, then got up for another talk by Robert Reeves. Robert’s second talk was also on the moon, but focused less on his imaging methods and more on the processes that have shaped the moon, and the moon’s changing appearance under varying conditions of light and shadow. It was incredible stuff – I took a whole page of notes to guide my own future moon-observing.

Sunday night we had clearer skies than Saturday, but it was colder and a brisk north wind was blowing not long after dusk. None of us got M74. Down at the Obsession shed, folks were looking for it with even bigger scopes and failed to see it, so I’m confident it just was not visible that night. Possibly that was atmospheric, but the zodiacal light certainly didn’t help – it was a broad dagger of light stabbing up vertically from the horizon all the way to the Pleiades. I have never seen it so bright.

The other thing that shaped my Sunday night plans was the fact that Glenn did get M77, bringing his aggregate Messier total to 109. All of my bonus points from H400s would only help in the event of a tie, and the only was I could tie him was to get M30. And without M74, there was no chance for me to achieve my personal goal of getting all 110 Messiers in one night. So I needed to be up before dawn to try for M30, but there was no point in subjecting myself to a whole night of observing in the windy cold. I packed up the scope and moved into the lee of Jeff Barton’s camper and switched over to binoculars. I was still using the 3RF Fujinon 7x50s.

It was another Fujinon binocular that would provide the most memorable views of the evening: the 25×150 motorized bino chair. 3RF volunteer Gary Carter had set up the bino chairs and was touring people around the sky on Saturday evening, but I was too busy marathoning to partake. Sunday night I hopped in the big chair, Gary got the binos adjusted, and I was off.

In a word – WOW. I have been fortunate to get to observe with a lot of big telescopes, but I am not exaggerating when I say that using that bino chair was my favorite observing, ever. I just sat there comfortably in a padded chair and drove myself around the sky with the joystick, while enjoying hands-down the brightest, most immersive, most enjoyable views of the night sky that I have ever had. Six inches is a lot of light-gathering per eye. I don’t know the AFOV of the eyepieces but it is wide. It’s hard for me to even believe that the magnification was only 25x – everything subjectively seemed much bigger, because it was so much brighter and more detailed than I am used to. When I was cruising over to look at the Double Cluster, I kept getting distracted by all of the little open clusters that dot the Milky Way in and around Cassiopeia (I was coming in from the north). M78, near Orion, was so big and bright that at first I thought I had the wrong object.

In summation, observing with the Fujinon bino chair was a transformative experience – it changed my perspective on what observing could BE.

I knocked off a little before midnight with 60 Messiers in the bag, and went to get some sleep. I didn’t get up until 5:30, and I wasn’t back out on the observing field until 5:45.

I have read many accounts from observers under dark skies who said that when the summer Milky Way rose, it was so bright that they mistook it for a cloud. I had not previously experienced that for myself. But Monday morning I was headed out of the bunkhouse and I saw a bright, white cloud in the eastern sky. We’d been fighting the occasional cloud every other night, so when I saw that cloud out of the corner of my eye I thought, “Aww, crap, I need clear skies to get M30”. But when I turned my head to see how big the cloud was, and how extensive, it turned out to be the Milky Way in Sagittarius and Scutum. I should have known better anyway – Comanche Springs is so dark that actual atmospheric clouds aren’t bright, but dark. They show up as blank spaces in the starfields.

I didn’t get M30. I got the scope correctly placed this time, and I got to the target star, and I spent about 15 minutes alternately adjusting the zoom eyepiece and staring into the darkness. A couple of times I thought I saw something, but I couldn’t even hold it in averted vision, so it could well have been a case of averted imagination. Anyone who has pushed their gear to its limits in the search for faint fuzzies will know the feeling. There are the things that you see repeatably in the same place, with the same orientation, that you log as detected – and then there are things that never swim up out of the minor variations in background darkness that your retina throws up when confronted with a blank slate. M30 never surfaced for me.

Ah, well. I did get 25 more Messiers with the 7x50s between 5:45 and 6:05. It helped that I had seen them all the previous morning with the telescope, so I knew exactly where to look. I probably could have gotten a few more, like M2, if I hadn’t been so fixated on M30. But 85 Messiers in one night with 7×50 binos is not a bad total at all, especially not when I got a 5.5-hour break in the middle.

I was too keyed up to go right back to sleep, so I went into the observatory classroom, made myself a Frito pie with a microwave bowl of Dinty Moore Beef Stew – which was awesome, by the way – and copied my results over from my personal log to the 3RF competition forms. Then I went back to sleep for a couple more hours.

We all reconvened in the observatory classroom around 10:00 for the final tally and presentation of awards. Here’s the scoreboard:

The highest aggregate total went to Glenn Winn, with 109 objects over the two nights. I got second in the Non-GoTo category, behind Glenn, and also got second in the Binocular category, behind Russ Boatright. In his naked M-cubed with the 18×50 bins, Russ got a staggering 90 objects. Color me impressed – very impressed. Jim Admire got 91 objects with his XT10g, and that was without pushing through dawn, so he won the GoTo category. Tom Monahan wasn’t even going to turn in his sheet, figuring that his 47 objects from the first half of Saturday night would not qualify him for anything. But a lot of people who signed up didn’t turn in any results, so Tom got the pleasant surprise of third place in the Non-GoTo category. I think the Young Observer awards went unclaimed, as no actual youngsters participated in the marathon.

Here’s a shot of the winners’ circle. From left to right are:

  • Jeff Barton, our host and the competition judge;
  • Glenn Winn with his 1st place medal and aggregate score trophy;
  • Russ Boatright;
  • Jim Admire;
  • yours truly, and;
  • Tom Monahan.

Many thanks to 3RF volunteer Gary Carter for taking the photo, and for permission to use it here.

A good time was had by all, and plans are already being laid for next time. Turns out that Jeff Barton is a fan of double stars, and he visibly lit up when I brought the idea of a Double Star Marathon to his attention. Something like 80 globs are visible in the fall during fall Messier Marathon season, so some kind of glob marathon may be in the offing in the near future as well.

I learned some things about my gear, too. The Bresser/Manfrotto/Dwarfstar rig was utterly uncomplicated, as I suspected from my test run at the Salton Sea the previous weekend. Rarely have I had more effortless and trouble-free observing. And I’m proud to have gotten 108 objects in one night with a 4″ scope – I don’t think there’s any shame in losing to a 17.5″ reflector, nor to an observer as experienced and friendly as Glenn. I might even have ‘sold’ a few of the Bresser Comet Edition packages, as there was a lot of curiosity about the scope among the star party attendees. I think Jeff Barton may have ordered one yesterday morning.

Is a 4″ reflactor enough scope for a Messier Marathon? It wasn’t this time. I’m not hurt about not getting M74 – if people with 17″ and 18″ dobs couldn’t see it, then conditions were just not right for it to be seen, period. M30 is more troubling. I know for dead certain that I was pointed at the right place, and I tried every trick in the book – averted vision, tapping the tube, slowly sweeping – and still couldn’t get it to pop out, and this was from its rising onward. But I know it was visible in bigger scopes. Sure, it will be a few degrees higher by the end of the month, but M74 will be a few degrees lower, too.

Now, I know that people have gotten all 110 Messiers in one night with even smaller scopes. According to this analysis by A.J. Crayon, hosted at the SEDS Messier site, it has been done with a 60mm refractor. That is darned impressive. So theoretically, yes, under perfect conditions, a 4″ scope is more than enough. But your chances improve with bigger scopes. Still, even a 17.5″ scope wasn’t enough to get all 110 this time, at this site. And it is worth noting that I’ve now done just as well with a 4″ scope as with my Apex 127, having gotten 108 objects in one night with both instruments.

Flying with the Bresser Comet Edition turned out to be surprisingly easy. I got scope, tripod, alt-az head, and clothes for five days into a standard duffel bag. The likelihood of this scope racking up more airline miles in the future is very high. And the 28mm RKE and 8-24mm Celestron zoom were all the eyepieces I needed. I didn’t use a finder of any kind – I didn’t take my green laser pointer for airport security reasons, and I forgot to borrow one from Jeff (who did offer) before the marathon started Saturday night. But it was okay, I just did my dead reckoning trick and didn’t even think about it after the first few objects. On the flip side, I did wish for a different atlas. I really need to suck it up and take the Jumbo PSA next time. At 4:00 in the morning when my eyes are tired and I’m trying to read by the dim light of a red headlamp, the writing in the standard edition is just too small.

I have new ambitions about gear – mainly, that I gotta get me some big binoculars. Frequent commenter and sometime observing buddy Doug Rennie has 20×80 bins that he mounts on one of these – that would be a potent and enjoyable combo for a very reasonable outlay (although I see that the price has crept up from the $65 or so it was going for last year). And my new no-holds-barred, price-is-no-object dream observing rig – which I may never achieve – is a motorized chair with 150mm binoculars. It was that good.

But ultimately the star party was not about gear, it was about experiences. I had a fantastic time at Comanche Springs, saw amazing things in the sky, learned a lot from my fellow amateurs, and most importantly made a lot of new friends. Many thanks to Jeff Barton and the whole 3RF crew for their hospitality and for making my trip possible. I don’t know when I’ll be back out there, but I’m already looking forward to it.

For more about Messier Marathons, including log sheets, links, and observing reports from previous marathons, see this page.

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Observing Report: more Messiers at the Salton Sea

March 21, 2017

I went to Mecca Beach again Saturday evening. Like my run at the end of February, it was a solo mission, decided on at the last minute. I made up my mind in the mid-afternoon and I emailed a few folks to see if anyone was interested, but that proved to be too little notice (not surprisingly).

I got a late start, didn’t arrive until about two hours after sunset, and there was a cloud bank to the west, so I missed out on all of the early evening Messiers. I skipped right over the winter objects, having spent the last 6 weeks observing them repeatedly with a variety of instruments.

Gear

I’m flying to Texas this weekend for a Messier Marathon star party – more news on that soon – and I’m taking the Badger along. I’ve flown with little Maks and with an AstroScan once, but this will be my first time flying with a refractor. I’ve had this trip in mind for a while – it’s why I was so excited to find that the Badger would ride securely and comfortably on my Manfrotto CXPRO4 plus DwarfStar rig, because that is an eminently flight-worthy mount and tripod combo. BUT the previous testing was just a short session in the driveway. I was curious to see how the Manfrotto/DwarfStar/Bresser setup would fare under semi-realistic conditions, on an extended observing run at a distant site.

I was also testing eyepieces. I want a travel setup that will be lightweight and low hassle, but that will still cover all the things I’m likely to want. My prime mover is the 28mm RKE. It is simply delightful and gives a bright view of a wide swath of sky. Next up is the Celestron 8-24mm zoom eyepiece, which covers most of the useful magnification range for this scope (19x-57x). I used this eyepiece a lot right after I got it. Then I was off it for a while – I went through a phase of doing a lot of high-power work with my Apex 127 and C80ED, and I thought (and still think) that the Celestron zoom was just a hair less sharp than the best of my non-zoom eyepieces, particularly the Explore Scientifics. However, my eyes are now the weakest link in the optical chain, even with glasses. So although I don’t get super-sharp pinpointy star images anymore (or at least, not until I get new glasses), I also don’t worry too much about whether my eyepieces are 100% sharp or only 97%.

I also auditioned some possible third players: the 32mm Plossl, just in case I needed more true field than the 28mm RKE will give; the 5mm Meade MWA for ‘high-power’ work (still only 92x); and the 2x Shorty Barlow. It turns out that I don’t need any more field than the 28mm RKE gives, so the Plossl is staying home; the MWA is nice but big, and not worth the bulk on this trip; and my Shorty Barlow has ever-so-slightly misaligned barrel pieces, so it won’t sit all the way down in the focuser. I’d noticed this before, but it didn’t bother me because all of my other eyepieces would come to focus anyway, but not, it turns out, the Celestron zoom. So the Barlow is staying home, too, and I’m planning to roll with just the 28mm RKE and the Celestron zoom.

Star Testing

I spent the first hour on just four targets: the Trapezium in Orion, the Pleiades, Jupiter, and Polaris. I looked at the Pleiades just to see them before they went down into the cloud bank over Palm Springs. The other three targets were to test the scope and the skies. The seeing was a little better than it has been for most of this spring, but still only so-so. The Trapezium was bouncing around too much for me to resolve the E and F components, although I suspected E a couple of times.

Jupiter looked a lot better than it has so far in this scope. I think that was partly a little better seeing, and partly the result of having collimated the scope. As I mentioned in the last post, the view of Jupiter at 92x was mesmerizing, with finely-divided belts and zones resolved all the way to the poles. I was using the 60mm aperture mask to knock down the CA, and that might have helped with the seeing and with other aberrations.

When I had stared at Jupiter for about 20 minutes, I removed the aperture mask and did a proper star test on Polaris. I’m not an expert at star testing but I know a little, and I have a copy of Suiter’s book, Star Testing Astronomical Telescopes, on loan from a friend in the club. I sketched the results inside and outside of focus and compared them to the diagrams in the book when I got home. The scope has about 1/4 wave of spherical aberration. That’s not great – it’s flirting with being not diffraction-limited, and it helps explain the scope’s so-so performance on solar system objects and double stars. On the upside, the perfectly-concentric diffraction rings confirmed that the scope is now in good collimation.

Binocular Messier Hunting

The best sky conditions of the evening were in the hour on either side of midnight. The cloud bank to the west was still there, but it had retreated down near the horizon. Transparency was as good as it was going to get. Lying down in a lounge chair and looking up naked-eye, I could make out sixth-magnitude stars at the zenith. After spending a good chunk of time at the telescope looking closely at a handful of objects, I was ready for a change of pace. I grabbed the 7×50 binoculars that came with the Bresser Comet Edition package and hopped in the lounge chair for a Messier tour.

I started with some galaxies in Ursa Major. M51, M81, and M82 were all easy, as were M94 and M63 in Canes Venatici. Then I jumped over to Corvus to pick up M68 and M104. After that I went to Coma Berenices and spent a while just staring into the Coma star cluster. It’s a true open cluster, and it looks huge because it is only 288 light years away. That’s farther than the Hyades (~150 light years), but closer than the Pleiades (380-440 light years, depending on the source), and the size of the Coma cluster is nicely intermediate between those two as well.

My first Messiers in this area were the globular clusters M3 and M53. Both were easy catches, and M3 was so bright I had to look twice to make sure it wasn’t a star. Seeing them in binoculars brought back fond memories of the very first time I ever observed them. It was the spring of 2008, and we were still living in Merced. I was on a backyard campout with London, who was only 3 1/2 years old. We were using my old dome tent, and as soon as London went to sleep I poked my top half out onto the grass and did some binocular stargazing. That was the first time I ever saw M3 and M53 with my own eyes.

My next target was the galaxy M64, and it was bright and obvious – so much so that it seemed to pop out from the background, the way that planetary nebulae sometimes do. M65 and M66 were not so pronounced but they were still easy prey. M95, M96, and M105 took a little more work and chart-checking, but I managed to bag them all. Later in the morning, after I’d gone back to the scope, I picked up the globular clusters M13 and M92, and the open clusters M6, M7, and M11.

I know that other observers have seen all 110 Messier objects with 7×50 binoculars – Jay Reynolds Freeman reports having done so in his essay, “Messier surveys“. I’ve seen all of the Messiers in my 15x70s and most of them in 10x50s, but I’ve never even attempted them in 7x binos. So I am working on a proper Messier survey with these 7x50s, and so far I’m up to 40 objects. Here’s my visual log – I’m highlighting objects in green as I observe them:

If you’d like a similar record sheet for your own observations, here’s a blank one:

A Varmint of the Skies

After an hour of binocular observing, I was ready for a stretch, and also champing to track down some of these objects with the scope. I had gotten through most of them with the scope, and I was about to make my assault on the Virgo galaxies when the moon rose.

I thought that contrast had dropped off a bit, and I was seeing fewer faint stars, and the rising moon made the reason clear: a high, thin haze had developed over most of the sky. Galaxies that had been dead easy in the binoculars just an hour before were now completely invisible in the scope. I missed out on M63, M94, and M101, and abandoned my Virgo galaxy hunt. I watched the moon rise through my binoculars, then I switched to double stars for a while. I’m not going to say much about that right now – suffice it to say that the results of my double star observing will be coming to a newsstand near you this fall.

After I’d done my double star ‘homework’, I was feeling very pleased. At the start of the evening I’d written down three goals for the session: “Messiers, double stars, chill”. With the first two activities done to my satisfaction, I was content to engage in the third. I spent more time looking at Jupiter and the moon through the scope, and a fair amount of time just sitting on a picnic table and looking up with my naked eyes. The haze had thinned out somewhat by 3:00 and I was just happy to be out under the stars. Although there were people camped just a few hundred feet from me, I had the place all to myself. Even the coyotes had stopped yipping and howling.

Back at the scope, I spent a while looking around in Lyra. My favorite astronomical axe to grind is that the “celestial sphere” compresses almost limitless space and time into what looks like a dome over our heads. As I put it in this article (and this even earlier blog post), I’m constantly trying to “shatter the bowl of the sky, to see space as space”. Lyra is a good area in which to do this, with objects as close as Vega – a scant 25 light years away – and as distant as the globular cluster M56, which lies 33,000 light years away. I’ll probably write a whole post about that soon.

Usually if I’m up that late at this time of year, I go through the “steam from the teapot” Messiers in Sagittarius and Scutum. But an unfortunate cloud was camped out in my way. I did pick up M11 in Scutum, and M6 and M7 near the ‘stinger’ of Scorpius, with both the binoculars and the scope. I also had a nice long look at the False Comet cluster near Zeta Scorpii. The False Comet is a fantastic object for binoculars and rich field scopes – or maybe I should say “a fantastic set of objects”, since it includes the open clusters NGC 6231 and Trumpler 24, and other bright stars in the Scorpius OB1 assocation, of which both clusters are members.

I’m up to 43 Messiers with the Badger. There are 3 objects that I’ve seen in the Bresser binoculars but not yet in this scope: M63, M94, and M101. And there are 6 that I’ve seen in the scope but not yet in the bins: M5, M29, M39, M56, M57, and M79. I’m not worried about the mismatch – most of the objects I haven’t seen in the binoculars because I just haven’t tried yet. Although I am a little nervous about my ability to distinguish the smaller planetary nebulae from stars at only 7x. Still, it’s a fun hunt and so far I’ve seen almost everything I’ve attempted. Here’s the visual tally for the scope:

I ended back in the solar system. I had a nice long look at Saturn a little after 4:00 AM, and at 4:15 I was gazing at the moon when I fell asleep. After a lifetime in academia, I’m very good at sleeping sitting up, and I didn’t realize I had drifted off until my eyebrow brushed the eyepiece, ever so gently. I think that’s the first time in almost a decade of stargazing that I have actually fallen asleep at the eyepiece. I called it a night, dragged the lounge chair around to the west side of the car where it would be out of the sun, and slept until almost 11:00.

Verdict? Well, the scope is no planet-killer. Doing the star test confirmed what I already suspected. But if I use an aperture mask and keep both the magnification and my expectations modest, it still delivers rewarding views of solar system targets. And it continues to be a fantastic wide field, low power scope for deep sky work. I was also happy to find that the light Manfrotto tripod and DwarfStar mount were more than adequate. I did have to let the scope settle a little at high power, but for Messier sweeping the whole rig just got out of the way and let me observe, which is what I had hoped for. Finally, although I had other eyepieces sitting in the rack, I spent almost the entire evening using just the 28mm RKE and the 8-24mm zoom. So as a test of my travel kit, the evening was a resounding success – and a heck of a lot of fun to boot.

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Collimating a reflactor

March 20, 2017

One of the nice things about ‘reflactors’, like the ones shown here, is that they can be collimated just like reflectors – and at the fast focal ratios that reflactors typically work at, they’re likely to need it.

I don’t think I’ve ever blogged about collimation before. I haven’t blogged about how to do it because there are so many other sites that cover it already. I learned it myself from the book Astronomy Hacks by Robert Bruce Thompson and Barbara Fritchman Thompson, which is a pretty good book for anyone getting started with a telescope, and an absolute gold mine for anyone who owns a reflector. The Thompsons have nice step-by-step instructions, illustrated with photos, for making and using your own collimation cap, and for collimating using the Barlowed laser method.

Collimation is one of those things that seems forbiddingly complex until you’ve done it a couple of times, at which point it becomes so routine as to hardly be worth mentioning. In conversation with other amateur astronomers I usually compare it to changing a baby’s diaper – awkward and probably terrifying the first time or two, and a complete non-event the next thousand or so times.

The Badger and the Ferret both have Allen bolts on the back ends of their OTAs that look pretty much the same as those on the spiders of Newtonian reflectors. The central bolt controls the distance down the tube and the rotational facing of the diagonal mirror, and the three perimeter bolts control the mirror’s tilt. You can use a Cheshire sight tube or collimation cap and collimate a reflactor just like you’d do a reflector. You can also use the Barlowed laser method, which is what I did.

It’s a three-step process:

  1. Draw a set of concentric circles on a piece of graph paper to make a collimation target, and rubber-band this over the front of the scope.
  2. Pop a laser collimator (or any laser, really) into a Barlow lens and see where the beam lands.
  3. Adjust the rotation and tilt of the mirror until the beam is centered.

I did the first bit in my garage, which is why there’s so much crap in the background of the first photo. Then I realized that it would be a lot faster and easier if I could see what was happening to the beam while I adjusted the collimation bolts, so I carried the whole rig inside the house and into the bathroom and pointed it at the bathroom mirror. Once I had the collimation spot-on, I spun the scope a quarter turn to get the final photo, which is why our tropical-themed shower curtain is in the background of the second shot.

As you can see from the photos, the scope arrived a bit out of collimation. That wasn’t a huge deal for the kind of low-power scanning that I got the scope for, but it probably did degrade lunar and planetary images somewhat. I can tell you that after collimation, it does better. I got a mesmerizingly good view of Jupiter Saturday night at the Salton Sea, with gently ruffled belts and zones marching all the way to the poles, like the layers of crust in a good baklava. But that’s a story for another time.

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Young crescent moon, pleasant surprises, the Bresser gets a name

March 1, 2017

earthshine-feb-28-2017-450

Got out tonight for a few short burst of observing amidst other things. I set up the C80ED and caught the young crescent moon as it was going down. Above is my best shot. It is still wildly inferior to the one I have up in the banner image, to the right of the blog title. That one I shot with my XT6, which had about three times the light gathering ability and almost twice the angular resolution of the C80ED, and I got that shot one night earlier in the lunar cycle. That was back in the early days, when we were still living in Merced. From my driveway I had a straight shot almost to the horizon, so I could catch a 2-day old moon. Here I have lots of trees and buildings in the way, so I generally have to wait an extra night to get a shot at the moon from the driveway.

Then I was out again in the half hour before midnight to try some things with the Bresser Messier AR102S Comet Edition. First, I put it on the lightweight Manfrotto CXPRO4 tripod and DwarfStar alt-az mount that I have previously only used for much smaller scopes (example 1, example 2). Orion was going down over LA so it was pretty stinky, but I still had a long look at both the belt and the sword, and I powered up to split the Trapezium and Sigma Orionis. Then I swept up to hit M35 in Gemini, then back down to Meissa at the ‘head’ of Orion. I finished on Jupiter, using the 60mm aperture mask to knock down the CA.

bresser-on-dwarfstar-1

I was deliberately bouncing around the sky, looking at a variety of targets at a variety of magnifications, to see if the Manfrotto/DwarfStar combo would keep up. I’m a pretty forgiving observer – witness my near-pathological devotion to cheap scopes and stuff made out of junk – but one thing I just can’t handle is an undermounted scope. My first Mak was a 4″ which I hated and sold away before I realized that I hated it because I’d never put it on a solid mount. That experience left me traumatized when it comes to rickety mounts.

The Bresser/Manfrotto/DwarfStar rig doesn’t look like it should work. It looks like the definition of a spindly undermounted disaster. But it was fine. I never had any problem slewing, tracking, or focusing. It helps that the Bresser is lighter than it looks, and carbon fiber is a lot stronger than it looks.

(In the photo, I have the optional eyepiece rack attached to the DwarfStar – I don’t think I’ve ever shown a photo of the mount with it in place. It’s useful.)

I was also pleasantly surprised by the views I got of Jupiter. To get to a decent magnification I used the 8.8mm ES82, both natively (52x) and Barlowed (104x), and a Celestron 8-24mm zoom dialed down to 8 (57x). In both eyepieces I could see the North and South Equatorial Belts and stacks of minor belts marching away toward the poles. There was some CA, but I could minimize the effect by keeping Jupiter in the center of the field, and my eye centered over the eyepiece. The view was so good that I slipped out of gear testing mode and just stared for a few pleasant minutes. I was also happy to find that with the rubber eyeguard removed, I could see the entire field of the 8-24mm zoom at all magnifications while wearing glasses. Which I have to do now. In fact, the other night at the Salton Sea I made almost all of my observations with glasses on.

And lastly, the Bresser Messier AR102S Comet Edition – whew! – finally has a name. I posted on Cloudy Nights about the Messier survey I’m starting with it (thread here), and CN user ‘Glob’ wrote,

mwedel, I read and enjoy your blog, let me suggest nicknaming the 4″ “The Ferret” as King Louis XV called Messier.

I responded:

That is a lovely suggestion, and it put a huge smile on my face. One thing I haven’t blogged about yet is that basically by serendipity I managed to pick up an 80mm prototype of the Bresser ‘reflactor’. So now I have two, big and little, otherwise nearly identical. Ferrets are mustelids (weasel family), along with wolverines, badgers, skunks, fishers, martens, stoats, weasels, and otters. My late grandfather was an accomplished taxidermist and one of his stuffed badgers is sitting on top of a bookcase about four feet from me as I type. It’s just about the same size as the 4″ reflactor. So I’m going to take your charming suggestion, with one modification: the 80mm will be the Ferret, as I anticipate some effort to ferret out all the Messiers with it, and the 4″ is henceforth the Badger, because it can just knock them around with all that aperture. Thanks for helping me solve that long-standing and vexing problem!

So, it’s official now: from now on, the Bresser AR102S is the Badger, and the 80mm will be the Ferret. More info on the Ferret one of these days. I’m going out with this family photo of the two – Badger’s up front, Ferret looms behind:

bresser-ar102s-comet-edition-and-80mm-prototype-1

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Finally – the Bresser Messier AR102S Comet Edition at the Salton Sea

February 26, 2017

ar102s-at-dawn

Sometimes life is cruel.

(Did I say cruel? I meant ridiculously First World cushy, where a grown man can afford nice toys and has the time to play with them and blog about it. But within the context of this grown man’s play-time blog, sometimes life is cruel.)

To wit: my Bresser Messier AR102S Comet Edition (still sans snappy nickname) arrived on Sunday, January 29, just a few hours late for the new moon observing run at the Salton Sea that Terry Nakazono and I went on the night before. Since then it’s been mostly cloudy here, with poor transparency on the nights it hasn’t been totally socked in, so I’ve been misusing the scope on bright stuff like the moon and Jupiter. And waiting not-so-patiently for a chance to get out to dark skies and do some wide-field, low-power scanning.

I actually did get about 45 minutes of semi-dark time with the scope a week ago. I was on dawn patrol up in the foothills and I spent some time in the summer constellations before the sun came up. The views were bright and contrasty, but all it did was whet my appetite.

Friday night I finally got the scope out under decent skies, for a decent amount of time. I decided pretty late to go to the Salton Sea – originally we had other plans, but Vicki and London were wiped out from a long week, and the forecast said that Friday was the last clear night for a while, all over SoCal. I didn’t leave Claremont until almost 7:00 PM, and with set up time after I arrived at Mecca Beach, I didn’t start observing until 10:00.

Gear

I was rolling pretty light. I wanted to test the Bresser reflactor/bino set as a package, so I used the AR102S on the came-with mount and tripod. I essentially always have binos out while I’m observing, so I used the 7x50s that came with the scope. That was a novel experience – I usually roll with 10x50s or 15x70s. This was my first time using 7x binos for serious deep-sky observations.

The only way I broke with the Bresser package was with eyepieces. I did use the included 20mm 70-degree a few times early in the evening, and I briefly tested the 10mm 70-degree that just came in, but my most-used set for most of the evening consisted of the 28mm Edmund RKE, both natively (16.4x) and with a 2x Barlow (33x), and the 8.8mm ES82 (52x and 104x).

28mm-rke-in-ar102s

A word about the 28mm RKE. It is simply the most comfortable eyepiece I’ve ever used. There are several factors that play into that. One is the long eye relief. Another is the magical floating stars effect, which is real, and impressive. Finally, there’s the wide exit pupil it gives, which in the AR102S is 6.2mm. That’s probably wider than my pupils go these days (same is true of the 7mm exit pupil of the 7×50 binos). Using binos or eyepieces with exit pupils wider than your own will go is usually not recommended. The extra light falls on the muscles of your iris, not on your retina, so your pupil becomes an aperture mask, stopping down the system to a smaller working aperture. You could get just as much light delivered to your brain using a smaller instrument or eyepiece. But there is one positive effect of using a “too-wide” exit pupil: you can move your eye around a bit within the light beam, without any falloff in illumination. So “too-wide” exit pupils are very bright – maximally bright – and very comfortable. And if a bit of light is wasted, oh well, it’s not like the cops are going to come for you.

One nice effect of swapping the 28mm RKE for the 20mm 70-degree is that they have close to the same true field of view of 2.9-3.0 degrees, but the RKE gives a much sharper image with fewer aberrations. Unsurprisingly, since it’s bending light from the same true field into a much smaller apparent field. Normally, a 45-degree AFOV would feel downright claustrophobic to me these days, but for some reason the 28mm RKE doesn’t bother me. I think it’s the magical floating stars effect – most narrow-fields (okay, anything south of 50 degrees) feels tight, like looking through a soda straw, because so much my field of view is taken up by the inside of the eyepiece barrel. But with the 28mm RKE, there is no visible eyepiece barrel, so although the AFOV isn’t actually that big, it feels much more expansive.

I did have one minor gear screw-up: I forgot my laser. I haven’t installed a finder on the AR102S. Same with the C80ED, except for one or two nights early on. When I really need help I lay a laser finder along a straight edge and use it to point to things in the sky. On the C80ED, there are a couple of buckles on the tube clamp that together form a de facto trough like the one I built for the SkyScanner 100. On the AR102S, the finder bracket serves the same purpose. But I forgot my laser. So I did what I usually do, just dead-reckoned it. I’ve gotten to the point where I usually don’t even have to sight down the tube, I can just sort of look up and aim the scope and get the target within a 3-degree circle. The AR102S will go wider than 3 degrees – a 32mm Plossl or 24mm ES68 will give 3.6 degrees, and my 32mm Titan 2″ will go to 4.88 degrees. But none of those eyepieces do their thing with the same panache as the 28mm RKE – at least in this scope. I did get out the 32mm Plossl just in case I needed a wider ‘finder’ eyepiece, but it never made it into the focuser.

Goals

I had a program in mind. Long-time readers will know that I’m a big fan of Jay Reynolds Freeman’s astronomy essays, especially “Refractor Red Meets the Herschel 400”. More relevant to this post is “Messier Surveys”, in which Freeman relates his habit of running through all the Messier objects with every instrument he gets his hands on, from 7×50 binoculars to a 14-inch SCT. Despite my Messier Marathon attempts, I’ve never kept track of which Messiers I’ve seen with which instruments. I’m certain I’ve seen them all with the XT10, and I’ve seen almost all of them with my 15x70s, but beyond that, I have no idea. So I decided that the best way to properly test the Bresser would be to start a Messier survey with it.

To be clear, I had no intention of attempting an off-season or mini Messier Marathon. I decided to just go until I got tired. I also was not a purist – I looked at plenty of non-Messiers along the way, including some I had never seen and wasn’t planning to observe when I started.

And in fact, I started with some non-Messiers.

Perseus

When I started observing at 10:00, plenty of good stuff was getting perilously low in the west. The western reaches of Cassiopeia were already down in the Palm Springs/Indio light dome. I started with the Double Cluster and Stock 2 – my first time looking at them with the AR102S. They were spectacular as always. Then I swept up through the Alpha Persei Association and followed the eastern ‘arm’ up to NGC 1528. The cluster was fully resolved at 33x, but I thought it was prettier at 16.4x, when the dimmer stars trembled just at the threshold of resolution. I also checked in on NGC 1545, which is a much less impressive cluster and a much tougher catch since it is dominated by a bright foreground star. But my favorite observation in this area was another OC, NGC 1513. I tried this one at a variety of magnifications and it always ‘popped’ a little more in averted vision, as previously unresolved stars swam into visibility. Not one of the sky’s stunning showpiece objects, but delicately beautiful if you have the time to tease out its secrets (and the skies – it’s not bright).

I hit M34 on my way out, and of course I stopped at the Pleiades, which were very nicely framed at 16.4x.

Orion and Vicinity

After all of that, I realized that I had to get a move on if I wanted to catch M79, the glob in Lepus, before it set. I hopped over to snag it, and visited Hind’s Crimson Star while I was in the neighborhood. It was a tiny red spark in the 28mm RKE.

The whole sword of Orion fits into the field of view of the RKE. The Trapezium was nicely broken out into four stars at 33x with the Barlow. I had a quick look at Sigma Orionis and scanned the Belt and the big OB association just off Orion’s western hip. M78 was delightful. Even at 16.4x, the two foreground stars were visible and distinct from each other and from the background glow, and the western edge of the nebula showed a more abrupt cut-off, which lent the whole object the feel of a comet.

Binocular Tours

Up to this point I had been using the 7x50s to trace my star hops in advance, but now I really started to run ahead. One thing about writing my deep-sky tour articles for Sky & Tel – I usually remember all the stops and I can run through them quickly anytime I’m out. In this case, I started at Sirius and followed the path of my December 2015 article down through Canis Major, across Puppis – with a side trip down to Vela that was not in the article – and into Hydra (for M48). Then I picked up where my tour from this March started, running northwest through Monoceros and northern Orion before ending in Gemini. Running through both tours took about 10 minutes, and I saw a lot and missed a lot more. Seriously, that stretch of the winter Milky Way is just ridiculous. You can swing your optics over it again and again and not pick out all there is to see.

Then I had a long break to rehydrate, eat a snack, and get into my cool-weather getup. I’ll have to write a whole post about that sometime.

ar102s-set-up-for-observing

After the break I went back through almost all of that with the telescope, in part just to see it all with more than 50mm of aperture. I noticed some Herschel 400 objects in Puppis that I had never observed, namely the open clusters NGC 2479 and 2509. Both were dim swarms of faint stars that were still not fully resolved at 52x, but very pretty. I had not noticed them in the binos, but after catching them in the scope I was able to see them when I went back with the 7x50s. I was comparing the two clusters in the binos when a meteor flashed through my field of view, which is always a cool sight. I spent about half an hour trying to catch the planetary nebula NGC 2440, and even hauled out Interstellarum to help me get on target, but I never got a definite sighting. I’m going to have to study that one and come back another time.  I did catch NGC 2438, the planetary nebula that is superimposed on M46 but only about half as far off as the cluster. It was obvious at 52x but I couldn’t separate it from the glow of the cluster at 16.4x. Needless to say, it didn’t show in the binos.

Roaming

By the time I was finished retracing my winter Milky Way tours, the Auriga Messiers were getting low in the west, so I hopped over to check them out. After that I hit M44 and M67 in Cancer. M44 was just perfect at 16.4x – everything nicely resolved, but still compact enough to look like a coherent object. The stars in that cluster always seem to fall into geometric patterns to me, as if they were laid out using a grid system that got erased the morning after creation. I can’t think of anything else in the sky that gives me the same impression.

I also popped up north, past Iota Cancri and over the border into Lynx, to check on NGC 2683, a surprisingly bright and easy Herschel 400 galaxy that I had previously only observed with binoculars. (Want to know more about this galaxy and its neighbors? See the April 2017 Sky & Tel!) Since I’d seen it with smaller-aperture binos under worse skies, naturally it was an easy catch for the AR102S.

After that I turned south, to Omega Centauri. Although I haven’t written about it yet, when Terry and I were at the Salton Sea last month, I spent a long time looking at the monster ‘glob’ – actually the exposed core of a dwarf galaxy that was cannibalized long ago by the Milky Way. It’s a favorite spring target of mine when I have a good southern horizon. From Mecca Beach there is a definite light dome from El Centro and usually some near-horizon haze in the southwest – directly over the water. But Omega Centauri culminates between that particular Scylla and Charybdis. Last month I spent nearly an hour checking it out, using naked eyes, binoculars, and several levels of magnification with the C80ED. I could just get the outermost stars to resolve at 120x, albeit in imperfect seeing. This time was worse – about the same lousy seeing, and slightly worse transparency. I didn’t get any actual resolution, but I could make out pronounced differences in brightness across the face of the cluster. I also had a look at NGC 1528/Centaurus A, the famous radio galaxy. I think it should be naked-eye visible under optimum conditions, but my conditions were not optimum. It was obvious in the binos and showed some detail in the scope.

Then it was on to Corvus to check in on M104 and M68. I also observed the planetary nebula NGC 4361, I think for the first time. It’s bright but small, and it turned out that I could see it at 16.4x, I just didn’t recognize it – I had to go up to 52x to confirm that it was nonstellar. I also visited M83 while I was in that neck of the woods. What a wonderful galaxy, so big, bright, and obviously elongated even at low magnification.

By now it was almost 3:00 AM and I was getting pooped. I finished in Lyra, with Epsilon Lyrae and the Ring Nebula, M57. I couldn’t split the Double Double. That might have been the scope, but it might have been the skies – by this point there was a steady breeze blowing right in my face when I looked east. I have had other nights where the seeing was so bad that Epsilon Lyrae would not split. I did notice some CA around those stars at high power, which probably didn’t help.

I decided to finish with M57, which was fitting since it was a chance observation of that nebula with the TravelScope 70 a few years ago that got me hooked on refractors. I wanted to recreate the feel of that surprising low-power observation so I left in the 28mm RKE. The whole southern end of the parallelogram fit very nicely into the 3-degree field, with M57 showing as a pale little dot. Then I realized that I had stopped the scope down to 60mm while I was playing with the double star and had forgotten to take off the aperture mask. So I got to do one of my favorite tricks – reach up and pull of the mask while I’m observing, and watch the sky get brighter in a hurry, as if all the lights out there suddenly turned on. The nebula had been obvious at 60mm – at full aperture it was so bright it almost looked stellar.

ar102s-at-mecca-beach

Tally

I ended the night having observed several double stars and 46 unique DSOs with the telescope, of which only 22 were Messier objects. Three were Herschel 400s which I believe I observed for the first time – those were the open clusters NGC 2479 and 2509 in Puppis, and the planetary nebula NGC 4361 in Corvus.

I’ll have a more complete review along soon, but the Bresser Messier AR102S lived up to its middle name – it is a superb Messier-catcher. Every Messier I attempted was not just visible but easy at 16.4x. Will be interesting to try it on some of the smaller, tougher objects like M76. I think this will be my Marathon scope this year.

Don’t take this as a full-spectrum endorsement. When I do post a full review of the scope, I’ll have both good and bad to report. It’s not a good all-rounder, not a good first or only scope. But what it’s built to do, it does quite well.

The biggest surprise for me was how much I could see with the 7×50 bins. I didn’t catch everything, but of the 46 DSOs I observed telescopically, 34 were also visible in the binos, and some of the rest I simply forgot to check (the galaxy NGC 2683 comes to mind). There were more DSOs that I saw in the binos but didn’t take the time to log, including shedloads of clusters in Monoceros. I don’t know if I will be able to complete a Messier survey with the 7x50s – I reckon some of the smaller planetary nebulae will prove my undoing – but I’m at least going to make the attempt.

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From sub-aperture mask to replacement dust cap

February 23, 2017

aperture-mask-2-4-length-comparison

Here’s something dumb. The Bresser AR102S Comet Edition is optimized for two things: widefield, low-power scanning, and portability. At 20″ for the OTA it’s just within the bounds of airline carry-on-ability, but you can unscrew the dewshield and shave off another 4″, at which point the options for storage and transport expand wildly.

BUT the stock dust cap for the objective is dome-shaped, for no good or obvious reason, which means it sticks out about a full centimeter longer than necessary. When you’re thinking about flying with a scope, that is one centimeter more stupidity than you should have to put up with.

There’s another problem with the stock dust cap: when the scope gets cold, it gets loose and falls out easily. Nothing unique to this scope about that – I’ve had to shim the majority of my scopes’ dust caps for the same problem, including the C80ED and XT10. One cheap package of sticky-back green felt has kept me going since 2010. I think I’ve used almost a third of it.

Now, I already have a nice 60mm sub-aperture mask for this scope (construction details here). If I could plug the central hole securely, I’d have a replacement dust cap that would be shorter, would get tighter rather than looser if it shrunk in the cold, and would serve double-duty as both a dust cap and a sub-aperture mask. The problem was finding a plug the right size, with a good lip on it to keep dust out, that would grab the edges of the mask hole securely.

aperture-mask-2-1-tootsie-roll-can

And it’s the dollar store to the rescue again, with this container of Tootsie Rolls that is intended to double as a coin bank. The hard plastic lid snaps down into the cardboard tube very securely, and the plug bit is just a shade over 60mm in diameter.

aperture-mask-2-2-external

I used the Dremel and some sandpaper to enlarge the hole in the sub-aperture mask ever so slightly, and voila. There’s a small lip that runs around the top edge, and even a little recess in which to hook a finger and pull out the plug.

aperture-mask-2-3-internal

Here you can see the ridges on the plug. By sanding in short increments, I was able to fine-tune the hole diameter until the plug snapped in very securely, without stressing either piece. I need to put some tape or a little epoxy or something over the perforated slot, which is intended to be punched out so the candy container can become a coin bank. Or cut out the center and replace it with another, smaller plug, so I’d have a dust cap and two aperture masks in one package…

aperture-mask-2-5-dust-cap-replacement

Boom. Now the scope is a centimeter shorter for travel, and I don’t have to keep the sub-aperture mask in my eyepiece case.

What I really want is for someone with even rudimentary 3D modeling skills to create a series of nested aperture masks, like Russian dolls, in 10 or 20mm increments, which could be 3D printed on demand in whatever combinations people needed. Most of them could be standard sizes, with only the outermost adapter for each telescope model needing to be custom. Then you could order the adapter for your scope and whatever set of nested masks you wanted, or maybe all of them to simplify, so your 100mm scope could also be an 80mm, a 60mm, a 40mm, and even a 20mm (the “Galileo model”) if you liked, just by taking out the relevant bits from the dust cap. Sure, it would be gross overkill for most people, but for those of us who like playing “what if” (“what if my C80ED was a C40ED?”) it would be a godsend. And with 3D printing no-one would be stuck with a bunch of useless stock when the idea inevitably bombed.

Anyway, if someone would to that, it would save me the trouble of building my own “Mask-ryoshka” dust cap out of junk from the dollar store. But if I’m being totally honest, avoiding building my own stuff out of junk from the dollar store was never the point of the exercise, was it?*

* With apologies to Adam Savage.
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Me and the ‘Stig

February 19, 2017

This story started a few nights ago. I had been monkeying around with the AR102S, both at its native aperture and stopped down, and I decided to see how it compared to the C80ED. In particular, I wanted to compare the rich-field views of both scopes (such as they are here – I was observing from the driveway after all), so I was looking at the belt and sword of Orion. The results of that comparo were not very surprising – with it’s wider aperture and shorter focal length, the AR102S goes significantly wider and brighter, but the longer focal ratio and low-dispersion glass of the C80ED produce a better-corrected image.

What was not only surprising, but actively alarming, was that at low power I was getting ugly star images in the C80ED. Even in the center of the field, stars were not focusing down to nice little round points, but to crosses and shapes like flying geese. I wondered if my diagonal might have gotten banged up, so I swapped diagonals. The problem persisted. The scope will not reach focus without a diagonal or extension tube, and I don’t have an extension tube, so I couldn’t try straight-through viewing. Still, it was exceptionally unlikely that both of my good diagonals got horked in the same way.

I didn’t know what to make of that. I figured maybe the scope had gotten out of collimation somehow, and I was pondering whether to mess with it. It’s always been optically excellent and mechanically solid (overbuilt, in fact), and I was loathe to take it apart (as opposed to the TravelScope 70 and SkyScanner 100, both of which were crying out for disassembly).

Then a few days later I ran across this thread on CN, in which a guy was having the same problem I had. It sounded like it was more likely astigmatism (aka the Stig) in the eyes than in the telescope. Apparently it’s worse at low powers where the exit pupil is large, which makes sense – astigmatism is caused by having corneas that are out of round (football-shaped rather than basket-ball shaped), but as the exit pupils get smaller, the less of the cornea is involved in vision, and the more likely it is that the ‘active’ portion will approximate a radially even curvature.

astigmatism-of-the-eye

One commenter recommended making a little diaphragm between thumb and forefinger to stop down the exit pupil. I tried that, but it was awfully difficult to hold my finger and my eye all steady and in alignment. Then I had the idea of using a collimation cap from one of my reflectors. That stopped down the exit pupil to a 1mm circle, which made the image d-i-m, but the star images cleaned right up. Then I took away the collimation cap and tried the view with and without glasses, and the glasses also cleaned up the star images.

It wasn’t the scope, it was me. I have astigmatism, and it’s bad enough that stars look ugly at low power unless I wear glasses.

On one hand, that’s a big relief, because the C80ED scope has always been a rock-solid performer. Along with the Apex 127, it’s my reference standard for good optics. I was feeling a bit queasy at the thought that it might have gotten out of whack.

On the other hand, I now need to prioritize eye relief in my eyepiece collection. I have a bunch that are too tight to show the whole field when I’m wearing glasses. So I have some decisions to make.

That was the first major discovery of the night.

The second was that the AR102S can take 2″ eyepieces with the most minor tinkering. The 2″-to-1.25″ adapter at the top of the AR102S focuser drawtube screws right off. I had been worried that it might be permanently affixed, but when I tried turning it, it spun with remarkable ease. Once I had it off, I dropped in the 32mm Astro-Tech Titan, which is my only 2″ eyepiece, and the views were pretty darned good. Way wider than with any of my 1.25″ eyepieces, and pretty clean as well, although I need to a little more head-to-head testing on that score. Possibly the star images looked good because they were so small at only 14x.

bresser-ar102s-with-2-inch-ep

In any case, the 32mm Titan gives a significant boost in true field, from 3.6 degrees in the 32mm Plossl and 24mm ES68, to a whopping 4.88 degrees.

I don’t think there would be any advantage in going wider, at least in the AR102S. Astronomics seems to be out of Titans, but the equivalent 70-degree EPs are available through Bresser and Agena. The next step up would be a 35mm or 38mm, giving 13x and 12x, but those would push the exit pupil to 7.7mm and 8.5mm, and that’s just wasted light. At least in the AR102S – in the C80ED, longer 70-degree eyepieces would yield the following:

Focal length / magnification / exit pupil / true field

  • 35mm / 17.1x / 4.7mm / 4.1 degrees
  • 38mm / 15.8x / 5.1mm / 4.4 degrees

Either of those would be a good step up from the 3.7-degree max field that the 32mm Titan gives in the C80ED, without pushing the exit pupil uselessly wide.

Anyway, I’m just noodling now. The big news is that the C80ED is fine, I need to prioritize long eye relief in future EP purchases (and maybe thin the herd a bit?) so I can observe with glasses on, and the AR102S can take 2″ EPs after all.