Archive for the ‘Moon’ Category


Observing report: Saturday night stargazing on Mount Baldy

April 2, 2017

Waxing crescent moon, afocal shot by Eric Scott with Samsung Galaxy S6, shooting through Orion XT10 reflecting telescope.

London and I went up Mount Baldy last night with our friends Thierra Nalley and Eric Scott. Marco Irigoyen and Leandra Estrada joined us up on the mountain. We went up to look for comet 41P, but that didn’t pan out.

Since we went ostensibly to look for the comet, I brought the XT10 for firepower, and lots of binoculars. We got set up at Cow Canyon Saddle at about 8:30. Our first target was Orion, before it could sink into the light dome over LA. Second targets were the Pleiades and the Double Cluster. The Double Cluster in particular looked magnificent. I’ve been on a small-scope kick for a while so the XT10 hasn’t been out much, and I tend to forget what a potent instrument it is, especially under dark or semi-dark skies.

The skies on Mount Baldy last night were definitely semi-dark. Even three days shy of first quarter, the waxing crescent moon was bright enough to throw shadows and rather seriously degrade the darkness of the sky.

I tried for the comet but just couldn’t see it. I had the chart, knew where to look, and swept the area repeatedly with binoculars of all sizes and with the XT10, and I got bupkiss. This was after catching the comet easily in 7×50 binos every time I looked for it in Texas last weekend – but I wasn’t fighting any moon then. I think the comet is so big and diffuse that the surface brightness is low, and therefore it is easily swamped by moonlight. It certainly was not evident last night.

While we were in the neighborhood of the Big Dipper, we had a look at Mizar and Alcor, the famous double star in the dipper’s handle. Then for comparison we checked on Sigma Orionis, and then Marco wanted a look at Jupiter. After Jupiter we went on an extended tour of the deep sky, in which we observed:

  • M81, M82 (interacting galaxy pair)
  • M97, M108 (planetary nebula and galaxy in same field)
  • M3 (globular star cluster)
  • M37 (open star cluster)
  • M35 (open star cluster)
  • M104 (Sombrero galaxy)

In addition, we also saw three more open star clusters with our naked eyes and/or binoculars: the Hyades, M44, and the Coma Berenices star cluster.

We finished up on the moon, and then Jupiter again. We spent quite a bit of time getting pictures of both with Thierra’s and Eric’s phones. By coincidence, they both have the Samsung Galaxy S6, which has a very full-featured slate of camera options. Leandra is a pretty talented photographer and she was able to coach us on what settings to use. I think the results are pretty astounding, for handheld shots using phones. Here are the two best images of Jupiter, captured by me using Thierra’s phone and Leandra’s advice:

Here’s a composite of Jupiter and the Galilean moons – the planet was overexposed in the original to get the moons to show up, so I replaced it with the better of the two shots above.

And here’s a comparison screenshot from Sky Safari Pro 5 identifying the moons – from left to right in the above image they are Callisto, Europa, Io, and Ganymede.

As usual, the view at the eyepiece was about an order of magnitude more detailed than what the photos captured. One thing that I had never seen before with one of my own scopes was a band of ruffled white clouds within the north and south equatorial belts (the prominent orange-brown stripes on either side of the equator). The barest hint of this survives in the photos. It was a pretty mesmerizing view. For eyepieces we used a 32mm Plossl (37.5x), 28mm RKE (43x), 24mm ES68 (50x), 14mm ES82 (86x), 8.8mm ES82 (136x), and 5mm Meade MWA (240x). The most used were the 28mm RKE, 14mm ES82, and 5mm MWA. If you’re wondering why we used both a 32mm Plossl and a 24mm ES68 – since they give the same true field of view – we used the Plossl during the afocal photography because it gives a wider exit pupil, which is easier to keep the camera’s aperture centered inside.

Even though we missed the comet, I was pretty happy with what we did see – at least one of every major class of deep-sky object, including all of the stages of the life cycle of stars. In the disk of the Milky Way, new stars are born from vast nebulae of gas and dust, like Orion. In time, heat and light from the newborn stars push away the remnants of their birth clouds, leaving behind only the stars themselves, as open star clusters (‘open’ as opposed to globular). Over time, the stars in open clusters drift apart to become ‘field stars’ like the Sun, no longer gravitationally bound to their siblings. When the run out of fuel, stars blow themselves apart in supernovae if they are 8 times the mass of the Sun or larger, whereas smaller stars blow off their outer layers of gas to form planetary nebulae like M97. Whether stars die suddenly in supernovae or slowly as planetary nebulae, the matter blown out by dying stars enriches the galactic gas and dust clouds, and in time it will be incorporated into new generations of stars and planets. We are products of this process – all of the elements in our bodies other than hydrogen were born by fusion in the hearts of stars, and seeded into the galaxy’s spiral arms when those stars died.

Farther out, globular clusters like M3 orbit the core of the galaxy on long elliptical orbits that are not flat, but come looping in from all directions. The stars in globular clusters are typically very old, 12 billion years or more. We know very little about how and why globular clusters formed, and how they came to have such weird orbits. Probably they are some kind of developmental leftover from the formation of the earliest galaxies in the first billion years after the Big Bang – astrophysical fossils, if only we knew how to interpret them.

All of these processes are going on in other galaxies as well, especially spiral galaxies like M81, M104, and M108.

To put all of that into context, here are all of the objects we observed again, this time ranked from closest to farthest:

In our solar system:

  • moon – 240,000 miles or 1.3 light seconds
  • Jupiter – 370 million miles or 33 light minutes (currently – Jupiter is about 5 AU out from the sun, but right now we’re on the same side of the sun so it’s only 4 AU from us)

In our spiral arm of the Milky Way galaxy (the Orion spur):

  • Mizar and Alcor (double star) – 83 light years
  • Hyades (open star cluster) – 151 light years
  • Coma Berenices cluster (open star cluster) – 280 light years
  • M45 (Pleiades; open star cluster) – 440 light years
  • M44 (Beehive; open star cluster) – 577 light years
  • Sigma Orionis (multiple star) – 1255 light years
  • M42, M43 (Orion nebula; star-forming region) – 1344 light years
  • M97 (planetary nebula in same field as M108) – 2030 light years
  • M35 (open star cluster) – 2800 light years

In the next spiral arm out from the galactic center (Perseus arm):

  • M37 (open star cluster) – 4500 light years
  • NGC 869/884 (Double Cluster; open star clusters) – 7500 light years

In the galactic halo of the Milky Way:

  • M3 (globular star cluster) – 34,000 light years

External galaxies:

  • M81, M82 (interacting galaxy pair) – 11 million light years
  • M104 (Sombrero galaxy) – 31 million light years
  • M108 (galaxy in same field as M97) – 46 million light years

That is very satisfying to me, to take in such a menagerie of celestial objects, at so many scales and distances, in the space of a couple of hours armed only with a comparatively inexpensive telescope and an idea of what’s out there to be seen. I can’t wait for next time.

Saturday night astro crew. Left to right: Marco Irigoyen, Leandra Estrada, London Wedel, Matt Wedel, Thierra Nalley, Eric Scott. Photo courtesy of Eric Scott.


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.


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 (UPDATE: hey look, I did!).

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.


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

March 1, 2017


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.


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:



Why and how to make a sub-aperture mask for a refractor

February 11, 2017


Here’s the Bresser Messier AR102S Comet Edition with a homemade aperture mask. I just converted the scope from a 102mm f/4.5 to a 60mm f/7.7.

“WAT!? You took a refractor, the most aperture-challenged of the three basic telescope designs, and made it even smaller?”

Yup. For several reasons.

The first and most obvious is to control chromatic aberration (CA), also known as false color. Despite the name ‘achromat’, which literally means ‘no color’, doublet refractors without extra-low dispersion (ED) glass do show some false color, because their lenses do not bring all of the colors of light to the same focus point (they’re still a LOT better than scopes with a singlet objective lens, like those used by Galileo). For dim objects like galaxies, nebulae, and most field stars, the effect is not noticeable, even in large and optically fast scopes like the AR102S Comet Edition (nickname needed). But bright objects like the moon, planets, and first magnitude stars will be surrounded by purplish halos, and may have yellowish margins. In effect, the purple and yellow-orange parts of the spectrum are forming out-of-focus images that are superimposed on the main in-focus image.

The problem is that CA gets bad fast as refractors get bigger. There are a couple of standards that are commonly used to describe the focal ratio necessary to minimize CA to acceptable levels, the Conrady standard and the Sidgwick standard. By the Conrady standard, the focal ratio must be 5 times the aperture in inches; by the less stringent Sidgwick standard, 3 times the aperture in inches is good enough. Note that the standards describe focal ratios, not focal lengths, so they go up fast with increasing aperture. Here are some apertures, focal ratios, and focal lengths required to meet the Sidgwick standard:

  • 50mm (2″) : f/6 : 300mm
  • 76mm (3″) : f/9 : 684mm
  • 102mm (4″) : f/12 : 1224mm
  • 127mm (5″) : f/15 : 1905mm
  • 152mm (6″) : f/18 : 2736mm

This, along with mounting considerations, explains why reflectors and catadioptric scopes are progressively more common past 4″ in aperture. A 6″, f/8 Newtonian will be free of false color (as are all reflectors) and has such a gently converging light cone that it is easy to collimate and to focus – it’s easy for such scopes to achieve ‘planet-killer’ status if the mirror is good. A 6″, f/8 achromat will be a beast to mount and it will show lurid false color on bright objects.

But people still make, buy, and use such scopes! Why? Horses for courses: big, fast achromats can be superb deep-sky scopes, where chromatic aberration is typically not a problem. With the fixed sizes of standard eyepieces, achieving wide true fields requires short focal lengths (not just short focal ratios), and bright images require aperture, which drives the development of large but optically fast scopes like the AR102S Comet Edition. At f/4.5, it is well into ghastly CA territory on bright targets. The other night I stayed up late to catch Jupiter, and in the AR102S the planet wouldn’t even come to a clean focus. It was just a bright ball of light inside a sea of purple. I switched over to London’s 60mm f/11 Meade refractor and Jupiter snapped into a sharp and essentially color-free focus. There was a moon emerging from behind the limb of planet, already one moon-diameter out into black space, that was completely invisible in the CA-smudged view of the AR102S.

I’m okay with that – as I noted in a previous post, observing bright solar system targets with the AR102S is deliberate misuse of the scope. When I want good planetary views, I have a 5″ Mak and a 10″ Dob that can both be pushed to 500x (assuming the atmosphere is steady enough). But their max fields of view are pathetic compared to the AR102S – about 1.1 degrees for the Mak, and a shade over 2 degrees for the Dob, versus 3.6 degrees for the refractor, which is enough to take in all of Orion’s sword at once, with space left over on either side.

Still, I’m not going to take all of my scopes out with me every time I go observing, and chances are good that at some point I’ll want to look at something bright even if my main goal for the evening was low-power sweeping with the AR102S. Under those circumstances, it’s easier to have an aperture mask shoved in my eyepiece case than to pack a second scope. Hence this project and this post.

But I’m getting ahead of myself. There are other reasons to stop down a scope besides reducing CA:

  • To reduce glare from bright objects. Mostly applies to the moon when it’s full or very gibbous.
  • To give a more aesthetically pleasing image when the seeing is bad. Opinions differ on this point. Some folks prefer to look through a larger aperture despite the increased susceptibility to bad seeing, on the grounds that in the moments when the atmosphere does settle down a bit, you’ll see more detail. I suppose it depends on whether one is in exploration mode or aesthetic observation mode.
  • To make it easier to focus. F/4.5 is a steep light cone, and it’s easy to overshoot the point of best focus. Stopping down the scope makes a shallower light cone, so it’s easier to watch the image transition from out of focus, to near focus, to in focus. I’m going to test this method of finding best focus on some close double stars.

I had done some calculations in advance to figure out what sizes of aperture masks I’d want to try out. Given that the AR102S has a fixed focal length of 459mm, here are the focal ratios at full aperture and at 10mm decrements:

  • 102mm gives 459/102 = f/4.5
  • 90mm gives 459/90 = f/5.1
  • 80mm gives 459/80 = f/5.7
  • 70mm gives 459/70 = f/6.5
  • 60mm gives 459/60 = f/7.7
  • 50mm gives 459/50 = f/9.2
  • 40mm gives 459/40 = f/11.5


I didn’t want to trade away too much resolving power, so I tested the scope on the moon using cardboard masks of 76mm and 60mm, made from the light cardboard spacers from a box of wet cat food. The 76mm is shown above. Perhaps unsurprisingly, at this aperture and focal ratio (f/6) the view was still unappealingly soft. But 60mm looked good, with minimal CA. This makes sense – the working focal ratio of f/7.7 is a healthy step beyond the f/7.2 that the Sidgwick standard suggests for a 60mm aperture. Going any smaller would be trading away valuable resolution, without significantly improving the image.


The light cardboard aperture masks were fast and easy to make, but they weren’t very sturdy. To make a more permanent mask, I needed plastic, heavier cardboard, or foam-core board. So I unscrewed the dewshield from the scope and walked down to the dollar store, where I looked for food packages and storage containers that might fit. Finally on the last aisle I found this 1-gallon plastic jar. The lid slip-fit over the dewshield with just a bit of extra room, which I knew I could shim out with some sticky-back felt.


I wanted to make sure the lid would fit before I did the hard work of cutting, so I put the felt on first. This was very familiar – it seems like every other scope I get has a loose dust cover that has to be shimmed to fit correctly. I’ve been slowly chipping away at the same package of sticky-back felt since 2010. I didn’t have a compass handy, so I used a small paper ruler to make a ring of marks around concentric 60mm circle inside the lid. Then found a lid to a jar of vitamins that was exactly 60mm in diameter and used that to trace the circle neatly.


I was going to cut out the aperture using hobby knife, but the plastic was too tough. So I moved up to a box knife, and then a linoleum knife. Then I said heck with it and got the Dremel. The hole I cut wasn’t perfectly circular and had rough edges to boot, so I wrapped some sandpaper around a pill bottle to make a tool for rounding out the aperture.


Here’s the scope before…


…and after.

Even with the aperture mask, the AR102S is not a champion scope on solar system targets. The C80ED blows it away, which makes sense – it has a 33% resolution advantage over the stopped-down AR102S, and frankly just better glass. But at least the view now is clean and not appallingly degraded. A dramatic way to see the difference is to get a good tight focus on the moon with the mask on, then quickly take it off without removing one’s eye from the eyepiece, and watch the view get a lot brighter and a lot softer at the same time.

I have a few more things I want to do. The 60mm aperture mask fits over the end of the scope so securely that it could work as a dust cover, if only I can find or make something to plug the central hole. Also, I think I am going to play with making aperture masks in other sizes, just to see what happens.

And finally, I have another 4″ scope that will be fun to make an aperture mask for. But that will be a subject for another post.


Misusing a fast reflactor: moon-gazing with the Bresser AR102S Comet Edition

February 1, 2017


I was going to hold off before I posted anything on the performance of the Bresser Messier AR102S Comet Edition (which I swear I am going to start calling something else, just as soon as I think of a good nickname). That’s because I haven’t had a chance to try it out under the conditions where it is likely to do well. This is an optically fast scope, optimized for low-power, widefield scanning, ideally under dark skies where those faint stars can really pop. A great time and place to test-drive this scope would have been last Saturday night at the Salton Sea, right after the new moon, when Terry Nakazono and I stayed up observing almost to dawn, (expect that observing report in the not-too-distant future).

Unfortunately, the scope arrived Sunday afternoon, a day late for our Salton trip. Mount Baldy is covered in ice and snow, and I haven’t had time on these school nights to get up there anyway, much less to get to anyplace farther away. And the skies down here in Claremont have been crappy this week. Never clouded out, but never truly clear either – there has been a thin, high-altitude haze that is really good at both obscuring dim stuff and reflecting light pollution. So the only objects that have looked good are the bright, small things – the moon, Venus, Jupiter, and double stars. In other words, exactly the things that the AR102S Comet Edition is not specialized for.

So I don’t feel like I can give the scope a fair review yet, because all I’ve been able to do with it are the things it’s not built for. It’s like taking a Lamborghini Huracán on a Moab jeep trail – it’s not going to work out well, in ways that are completely predictable, and you’re not going to learn very much by doing it.

But when has that ever stopped me? I may not be able to review the scope, but I can still play around with it.


Here’s a raw shot of the moon, taken with a Nikon Coolpix 4500 shooting afocally (and handheld) through the supplied 20mm 70-degree eyepiece.


Same shot tweaked with Unsharp Mask and Curves in GIMP.


And then converted to black and white.

I didn’t learn much. Yes, there is chromatic aberration. In other news, water is wet and the Pope is Catholic. On the plus side, the Trapezium in Orion is split into four members at 23x. Haven’t tried it on the Double Double or any other double stars, really.

On the to-do list are (1) to get this scope out someplace dark and clear and really put it through its paces, at a variety of magnifications – and using a variety of eyepiece designs – on a variety of targets, (2) to do some actual testing on close double stars and doubles with significant magnitude differences, and (3) to experiment with sub-aperture masks to knock down the CA on bright stuff. “Why not just use a smaller or better-corrected scope?” you may wonder. Well, this is sold as a travel kit, and if by using a sub-aperture mask I can make it into a passable solar system scope, I’ve just made it a better all-rounder when and if I take it on the road.

Given the waxing moon and the continuing lousy forecast for the coming week, I’ll probably have to tackle that to-do list in reverse order. Stay tuned.


Parting shot. I got this Earthshine pic by doing a half-second exposure with the Coolpix. It’s not nearly as good as the one in the banner at the top of the page. I need to try again next cycle when the moon is younger.


Small, medium, large – observing near and far in the last two weeks

June 4, 2016

Matt at Delicate Arch IMG_2984

Preface – Running with the Red Queen

I’ve just finished maybe the busiest spring of my life. January and February were largely sunk into day-job work – time-consuming, but necessary, interesting, and in fact rewarding. Then the last three months have been taken up with travel and public lectures.

  • In March I went to Oklahoma for 10 days of paleontological research in field and lab, and I gave a talk at the Oklahoma Museum of Natural History titled, “Dinosaurs versus whales: what is the largest animal of all time, and how do we know?”
  • In April I did a two-day trip to Mesa, Arizona, for more paleo work. No talk on that trip, but I did participate in the “Beer and Bones” outreach at the Arizona Museum of Natural History.
  • In early May I was in Utah for another 10 days of paleo research, and I gave a talk at the Prehistoric Museum in Price on, “Why elephants are so small”. My colleague Mike Taylor and I took one day off from dashing through museums to tour Arches National Park, which is where Mike took the photo at the top of the post.
  • Last weekend I was up at RTMC, where I gave a Beginner’s Corner talk on, “The scale of the cosmos”.

I’m not complaining – far from it. It’s been exhilarating, and the collaborative work I have rolling in Oklahoma and Utah will hopefully be paying off for years. And planning and executing all of the work has been satisfying. Particularly the RTMC talk, which deserves a whole post of its own. And ultimately this is all stuff that I chose to do, and if I could do it all over again, I would.

BUT there have been consequences. Most frustratingly, I haven’t had enough uninterrupted time to get anything written up for publication – not the sizable backlog of old projects I need to get finished up, and not the immense pile of new things I’ve learned this year. I haven’t gotten out to observe as much as I’d like, and I’ve barely blogged at all.

And it’s not over. In two weeks I leave for a week of paleo fieldwork in Oklahoma, then I’m back for a week, then I’m off to Utah for about 10 more days of digging up dinosaurs. In between I’ll teaching in the summer human anatomy course at WesternU.

But I’ve had a nice little pulse of observing in the last couple of weeks – two weekends ago up at Arroyo Grande, near San Luis Obispo, last weekend at RTMC above Big Bear, and this week at Santa Cruz Island off the coast. No time for separate observing reports, so I’m combining them all into one.

Observing Report 1 (Medium): The Planets and Moon from Arroyo Grande

I was fortunate to be part of a great, tightly-knit cohort of grad students at Berkeley. Of the people I was closest to, some are still in and around the Bay Area and some of us have been sucked into the gravity well of the LA metro area. Occasionally we get together somewhere halfway in between, either up in the Sierras or near the coast. I usually take a telescope, because almost everywhere is darker than where I live, and when I’m traveling by car there’s simply no reason not to.


This year we met up for a couple of days and nights in Arroyo Grande. We hiked in the hills, went down to Morro Bay to watch ocean wildlife and buy seafood, played poker, and generally got caught up on work, family, hobbies, and life. Our first night was wonderfully clear. I had along the trusty C80ED, which has become my most-used scope. It’s mechanically rugged, optically damn near perfect, and compact enough to not require much time or thought when it comes to transportation and setup. On Saturday, May 21, we spent some time with Jupiter, Mars, and Saturn. Jupiter and Saturn were as they always are: beautiful and surprising in their immanence. I cannot look through the telescope at either of them without being forcefully reminded that they are as real as I am, that as I go about my days full of busyness and drama, they are always out there, hundreds of millions of miles away, go about their own business whether I or anyone else pay them any attention or not. One of my friends had never seen the rings of Saturn with his own eyes, so that was an added bonus.

Mars was the real treat. Using the Meade 5mm 100-degree EP and a Barlow I was able to crank up the magnification to 240x. The dark dagger of Syrtis Major and the white gleam of the north polar cap were both obvious. It is always arresting to see details on this world that has loomed so large in the human imagination, from ancient mythology to science fiction to current and future exploration.

The next night we sat out on the patio, eating oysters and watching the sun set. I didn’t have any of my own binoculars along, but a friend had brought a couple, and after it got dark we watched the still-mostly-full moon rise through the trees on the ridgeline to the east.

It was all shallow sky stuff (solar system, that is), but it was all spectacular, and I’m glad we did it.

Observing Report 2 (Large): Going Deep at RTMC

Last weekend I was up at RTMC, finally. I’ve been wanting to go since I got to SoCal, but in the past it’s fallen on the same week as our university graduation and I’ve been too wiped out. I didn’t make it up for the whole weekend. We went up as a family to stay Saturday and Sunday nights. I went up to RTMC early Sunday morning to look around, give my talk, and hang out. Ron Hoekwater, Laura Jaoui, Jim Bridgewater, Ludd Trozpek, and Alex McConahay of the PVAA were all there and we spent some time catching talks and jawing about skies and scopes. I also chatted with some folks from farther afield, including Arizona and NorCal.


I took off in the afternoon to spend time with London and Vicki, then went back up after dinner. All I had along were my Celestron 10x50s (yes, those), but Ron had his 25-inch Obsession dob, and he was content to use it as the centerpiece of a group observing session. We looked at the planets, or at least Jim Bridgewater and I did – Ron had checked them out the previous night and didn’t want to blow out his dark adaptation. That was a smart call, as the Obsession gathers a LOT of light and the planets were almost blown out. We could have put in a filter, but ehh, we had other things to be getting on with.

We started with globular clusters. M3, M5, M53, NGC 3053, and one or two other distant NGC globs. The close ones were explosions of stars that filled the eyepiece. The distant ones shimmered out of the black like the lights of distant cities. Then we moved on to galaxies. M81 and M82 were bigger, brighter, and more detailed than I had ever seen them. M51 was just stunning – the spiral arms were so well-defined that it looked like Lord Rosse’s sketch.

M51 sketch by Lord Rosse

As nice as those were, the Virgo galaxy cluster was better. There were so many galaxies that identifying them was a pain – there were so many little NGCs in between the familiar Messier galaxies that my usual identification strategies kept getting derailed. It was kind of embarrassing, actually – I did just write an article about this stuff. But also incredible. NGC 4435 and 4438 – the pair of galaxies known as “The Eyes” – were so big, bright, and widely separated that I didn’t realize I was looking at them until the third or fourth pass.

We finished up on planetary nebulae. The seeing was good but not perfect – the central star in the Ring Nebula was visible about a quarter of the time. The Cat’s Eye, NGC 6543, was a fat green S with a prominent central star – it looked like it had been carved out of jade.

An evening under dark skies with a giant scope is both a blessing and a curse. A blessing because you get to see so many unfamiliar objects, and so many details in familiar objects, that are beyond the reach of smaller scopes. A curse because by the end of the session you may find yourself thinking, “Sheesh, why do I even bother with my little 3-, 5-, and 10-inch scopes?”

Fortunately another observing experience, one that would remind me of the joys of small-aperture observing, was right around the corner.

Observing Report 3 (Small): A Binocular Tour of the Spring Sky

My son, London, is finishing up fifth grade at Oakmont Outdoor School, one of the half-dozen or so different elementary schools in the Claremont Unified School District. We were fortunate when we moved to Claremont to land just a couple of blocks from Oakmont – we would have been happy to land within walking distance of any of the schools, but if we’d had our choice we would have picked Oakmont anyway, since we wanted to raise London with as much exposure to the outdoors as we could.

Oakmont’s slogan is, “Learning in the world’s biomes”. The major activities of each grade are organized around a particular biome, and so is the end-of-year field trip. In third grade, the kids went to Sea World. Last year it was the desert by Palm Springs for a 2-day, 1-night trip. This year it was Santa Cruz Island, in Channel Islands National Park, for a 3-day, 2-night trip. Parent chaperones are needed and I’ve been fortunate to get to go every year.


The island was amazing. We saw dolphins, sea lions, and petrels on the boat ride out – I took the photo above from the prow of the ship – more sea lions, seals, pelicans, cormorants, gulls, and red pelagic crabs at the shore, and dwarf island foxes, ravens, and the occasional hawk inland. On the final evening, June 2, we hiked up to the top of the cliffs to watch the sun set over the Pacific, which was one of the most beautiful things I have ever seen in my life. I didn’t know it at the time, but I’d see something even more beautiful just a few hours later.

I had binoculars along – Bushnell 10×40 roofs that I got specifically for daytime use, and which I had used a lot on the trip already to watch wildlife. When we got back to camp, a few of the teachers and hung back and started talking about the planets, bright stars, and constellations. I started pointing out a few of the brighter targets and passing around the binoculars, and we ended up having an impromptu binocular star party. (The kids and a fair number of the adults were all exhausted from a full day of hiking, and sensibly went to bed.)


What followed was one of the best and most memorable observing sessions of my life. The only permanent residents of Santa Cruz Island are a couple of National Park employees, and they turn their lights off after dark. We got a little light pollution on the eastern horizon from Ventura and Oxnard, some 20 miles distant, but for the most part the sky was darkAfton Canyon dark, Hovatter Road dark – what I typically refer to as stupid dark.

We roamed all over the sky, looking at targets large and small, near and far, bright and dim. I didn’t keep track as we were going, but I wrote down a list yesterday morning on the boat ride back to the mainland (we went through a fog bank and only saw a handful of dolphins, so I had plenty of time).

In the northern sky:

  • Polaris and the Engagement Ring asterism
  • Mizar and Alcor
  • M51 – yes, it was visible in the 10×40 bins
  • The 3 Leaps of the Gazelle

In the western sky:

  • M44, the Beehive – easily visible to the naked eye, and just stunning in the binos
  • Leo
  • Coma Berenices star cluster
  • Virgo/Coma galaxies – identifications were tough, but a few were visible

In the eastern sky, Lyra had just cleared the trees when we started observing (at 9:15 or so), and all of Cygnus was above the trees when we finally shut down at 12:45 AM. In addition to tracing out the constellations, along the way we looked at:

  • Epsilon Lyrae, the Double-Double star
  • Albireo
  • Alpha Vulpeculae (the subject of my Binocular Highlight column in the ### issue of Sky & Telescope)
  • Brocchi’s Coathanger (Collinder 399)
  • Sagitta (just traced the constellation)
  • M27, the Dumbbell Nebula
  • Sadr and its surrounding ring of stars in the heart of Cygnus
  • NGC 7000, the North American Nebula – this and the Northern Coalsack were easily visible to the naked eye once Cygnus has risen out of the near-horizon LP

…and we just cruised the Milky Way from Cygnus to Cepheus, not singling out individual objects but just taking in the rich star fields.

But the southern sky was the best. Looking south from Santa Cruz Island, there’s only open ocean, broken here and there by other, distant islands and ultimately by Antarctica. It reminded me of looking south from Punta del Este in Uruguay, only I was in a valley instead of on a beach. The ridgeline to the south did cut off a bit of the sky, but we were still able to see all of Scorpio, including the False Comet, made up of NGC 6231 and Trumpler 24, which was one of the highlights.

It was trippy watching the Milky Way rise. I usually look at the summer Milky Way when it is higher overhead. I usually have to do that, because the objects aren’t visible in the near-horizon haze. But from Santa Cruz Island, things were not only bright but obvious as soon as they cleared the ridgeline to the south. It’s almost pointless to list them – we saw every Messier object in the “steam from the teapot”, from M7 and M6 in the south to M11 in the north, plus a lot of NGCs, plus star clouds and dark nebulae almost beyond counting. They were all great through the binoculars – M7 was a special treat, like a globular cluster on a diet – but honestly the best views of the night were naked-eye.

I realized that I am just never out observing the Milky Way at this time of year. My regular desert observing spots are all too hot in the summer, and when I do go there is often at least some light pollution to the south (El Centro from the Salton Sea, Barstow from Owl Canyon, etc.). I do most of my deep and dark observing in October and November, when the southern Milky Way is setting, not rising.

So I was completely unprepared for how much detail would be visible to the naked eye. When the Milky Way rose, it didn’t look like a band of light, it looked like a galaxy. I searched through a lot of photographs of the rising Milky Way to find one that approximated the naked-eye view, and this is the closest I got:

I am not exaggerating – the bright and dark areas were that defined. The Great Rift was visible from Cygnus to the horizon, and its southern border was notched by distinct deep sky objects from Aquila onward. The Scutum Star Cloud, M16, M17, M24, M23, M8, M6, M7, NGC 6281, and the False Comet were all easily visible to the naked eye as a chain of luminous patches against the dark dust lane of our own galaxy. In fact, I noted NGC 6281 with my naked eyes first, thought, “What the heck is that?”, and had to look it up. We also caught M4, M22, M23, and M25 in the bins, plus a bundle of dark nebulae that I’d never noted before and didn’t bother keeping track of.

Longtime S&T contributor Tony Flanders (now retired but still writing occasionally) is active on Cloudy Nights, and his sig file reads:

First and foremost observing love: naked eye.
Second, binoculars.
Last but not least, telescopes.
And I sometimes dabble with cameras.

Until fairly recently I would have listed my own preferences in reverse order, from telescopes to binos to naked eye. That may sound odd for a “bino guy”, which I guess I am since all of my ‘professional’ astro-writing has been binocular-based. But it’s true – as much as I love binoculars, I would have picked a telescope first. But I am – gradually, belatedly – waking up. In some ways, it would have been great to have a scope, any scope, along on the island trip. I’m sure that even the C80ED would have taken us crazy deep, considering what we could see with a pair of low-end 40mm roof-prism bins. But it would also have come between us and the sky, and I would have spent more time futzing with eyepieces and less time just looking up.

This was a surprising and welcome realization, coming so shortly on the heels of a frankly astonishing session with Ron’s 25-inch dob at RTMC. I was worried that big-telescope observing might spoil me, but that fear turned out to be unfounded. All I need to be happy is a dark sky. If I have some people to share it with, even better. Anything more is just cake at the end of an already long buffet.

Let’s eat.


Observing Reports: two perfect imperfect nights at the Salton Sea

November 23, 2015

Apex 127 ready for stars 2015-11-14

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

Terry Nakazono with Meade Polaris 114 2015-11-14

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

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

Matt aligning finder on Apex 127

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

Matt digiscoping moon

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

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

Jupiter and moons 0530 PST 2015-11-15

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

Clouds at dawn 2015-11-15

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

Waxing gibbous moon 2015-11-22

Back Again

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

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

Sigma Orionis sketch 2015-11-22

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

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


That planet above the scope is Venus, not Jupiter.

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

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


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