Archive for the ‘Travel’ Category

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My 9.5-pound observatory

June 27, 2016

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In the last post I introduced my new small scope, the PICO-6 60mm Mak-Cass. After having a positive first light, I decided the scope was good enough to be the center of a new travel observing kit. Here’s the scope mounted on a Universal Astronomics DwarfStar alt-az head and a Manfrotto CXPRO4 Carbon Fiber Tripod.

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Here’s the kit broken down. The case is an AmazonBasics Medium DSLR Gadget Bag, which Doug Rennie helpfully put me on to. The Pocket Sky Atlas and small Night Sky planisphere go in the back pocket. In front of the bag from left to right:

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Here’s everything packed away. This was just a first pass. The final arrangement I came to is as follows:

  • The left-hand slot holds the DwarfStar head with the handle removed and stowed separately, as shown here, and the 6mm eyepiece in its cardboard box, wrapped in a small piece of bubble wrap.
  • The middle slot holds only the PICO-6 OTA, just as shown here.
  • The right-hand slot holds the 32mm Plossl and the 8-24mm zoom eyepiece on the bottom, both of them in the beige metal cases that the zoom eyepieces come in (I had a spare). The tops of the two cases form a horizontal shelf which holds the diagonal, wrapped up in a small drawstring bag.
  • Finally, a piece of bubble wrap goes across the tops of all three slots and gets tucked in at the edges and corners.

Oh, the vertical dividers in the case are held in with velcro so they can be adjusted or removed as needed.

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For flight, the tripod can go in a backpack or in checked luggage, and the AmazonBasics case goes as my carry-on “additional item”. The tripod weighs 3.5 lbs, the fully-packed case weighs 6. For a total of 9.5 lbs, I have a full-size tripod, a smooth, variable-resistance alt-az head, eyepieces giving magnifications of 22x, 29-88x, and 117x, a scope which will show the Cassini Division and split Epsilon Lyrae, a planisphere, and a mag 7.6 all-sky atlas.

Oklahoma dig

This past week I was out at Black Mesa, at the northwestern corner of the Oklahoma panhandle, to dig up dinosaurs. I took the whole kit, and I used it. On Sunday night I showed half a dozen people the moons of Jupiter, the ice caps of Mars, the rings of Saturn, a couple of double stars, and the full moon. Monday night I was too pooped for stargazing. Tuesday I spend a couple of hours observing with my parents and a couple of other visitors who were also staying at the Black Mesa Bed & Breakfast. We looked at the same run of stuff as I had Sunday evening, plus a couple more double stars, the open clusterM7, and the False Comet Cluster in southern Scorpio, which is a visual amalgam of the open clusters NGC 6231 and Trumpler 24. After that, we were clouded out for the rest of the week, but it was still more than worth it to have the little scope along.

Verdict: an amazingly flexible and capable setup. I look forward to many more adventures with it.

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Here’s one more shot from the road. Nothing telescopic – on Thursday morning the rising sun was accompanied by a pair of sun dogs. This is a raw shot with my iPhone 5c. The best sun dogs I’ve ever seen in my life.

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A tour of Big Bear Solar Observatory

October 13, 2015

BBSO from up high

The gleaming white domes of the Big Bear Solar Observatory sit at the end of a causeway that projects from the north shore of Big Bear Lake – they draw the eye from almost any point in Big Bear Valley. And as I mentioned in my last post, the Pomona Valley Amateur Astronomers got to visit the BBSO on Friday, October 9.

BBSO causeway

We were greeted at the gate by Claude Plymate, Chief Observer and Telescope Engineer at BBSO, and Teresa Bippert-Plymate, who is not only a professional solar astronomer but also the president of the Big Bear Valley Astronomical Society. As pros who are also enthusiastic amateur observers, Claude and Teresa did a great job of pitching the tour with just the right balance of necessary background, technical detail, and the hands-on practicality of managing big scopes and the complicated hardware and software necessary to run them.

BBSO GONG scope

The first thing you come to on the causeway is a big white storage container with a coelostat (sun-tracking mirror) – this is one of the six Global Oscillations Network Group (GONG) installations spaced roughly equally around the world. The GONG telescopes track the sun around the clock for helioseismology research, mapping the acoustic pressure waves that propagate around and through the sun.

PVAA group outside BBSO domes

The smaller dome just short of the end of the causeway holds two telescopes on a common mount. One is a 10cm full-disc hydrogen-alpha solar telescope, the other is a second smallish refractor for Project Earthshine, which tracks the Earth’s albedo by measuring the intensity of the earthshine that falls on the moon’s unlit side.

London with BBSO New Solar Telescope

The observatory’s ‘big gun’ is the 1.6-meter New Solar Telescope, an off-axis Gregorian. One-point-six meters is 63 inches, which means this scope has a slightly larger aperture than the famous 60-inch reflector on Mount Wilson (which I’ve been fortunate to visit – see here and here). Here’s the light path of the NST (an unmodified version of this image is at the bottom of the post):

BBSO New Solar Telescope light path

And here’s a view on the right side of the scope showing the mask that rejects the light from most of the sun (which bounces onto the back wall of the dome, landing at about the same intensity as natural sunlight). The mask has a small hole which allows light from a small part of the sun to pass through to the chain of lenses and mirrors that bounce the beam to the research instruments on the next floor down.

BBSO New Solar Telescope right side optics

It took me a while to wrap my head around how this works. If the mask rejects most of the sun’s light, doesn’t that mean that most of the telescope’s 1.6-meter aperture is wasted? The answer is no – the mask functions as a field stop, not an aperture stop. If I put a mask across the front of my 10″ Dob and let only a 4″ beam of light through, that’s an aperture stop – it effectively turns a 10″ f/4.7 obstructed system into a 4″ f/12 unobstructed system (which may be desirable for sharp planetary and lunar views, where light-gathering is not so important). But imagine I left the front of the scope uncovered and instead masked down the field stop at the bottom of one of my eyepieces, so that I could only see a tiny hole in the center. If I put the scope on Jupiter, I’d see Jupiter in the center of the field but nothing else – I’d be getting the full benefit of the 10″ mirror’s light-gathering and resolution on Jupiter, but rejecting the light from the surrounding starfield, which would reflect off the mask at the bottom of the eyepiece. That’s more or less what happens with the New Solar Telescope, only “the rest of the field” is the rest of the sun, and the small area that the scope focuses on is not a planet but a small patch of the sun’s surface. But that patch can be imaged with the full benefit of the 1.6-meter primary mirror’s angular resolution.

BBSO burnt light shield

Now, a 1.6-meter mirror focusing the light from the full disc of the sun onto an area about 3cm across is a hell of a lot of energy. That beam could fry electronics, melt metal, and start fires if it got off-course. There are multiple redundant systems to prevent that from happening – the dome can close, the primary mirror has a cover that can activate quickly, and if all else fails a 1/16″ steel plate slides into position in front of the field stop. A few years ago – before Claude’s tenure as Chief Observer! – there were not so many safeguards in place. The software that allows the telescope to track the sun briefly got confused by some passing clouds, and the scope stopped tracking properly. That allowed the concentrated beam of sunlight to slide off-target. The steel plate did its job and slid into place, and the scope melted two holes in it in the space of about 30 seconds. The folks at the observatory keep the melted metal plate as a visible reminder that they are in a very real sense playing with fire.

BBSO sunspot image

This sunspot is a bit larger than our planet.

Our last stop on the tour was the telescope control room, where another professional astronomer was driving the scope and taking data. There was a minor mechanical hiccup at one point and Claude had to swing into action, running back and forth from the control room to the instrument room to get everything back on track. It was amazing to see live images coming in in real time. I’ve been fortunate to tour a lot of observatories but never while they were working. At one point Claude and the other astronomer put the scope on a sunspot group which was just swimming in atmospheric distortion. Once the computer had enough data to engage the adaptive optics, they switched on the AO and the view instantly settled down to nearly rock-solid, like it was painted on the monitor.

BBSO New Solar Telescope

The NST is currently the largest, best-equipped solar telescope in the history of humankind, and it is producing the sharpest images of the sun ever taken. BBSO joins Mount Wilson and Palomar in continuing the long, proud history of world-class astronomy in southern California. And it’s 65 miles from my house. Many thanks to Claude and Teresa for being such gracious hosts and letting us see their beautiful machines in action.

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Another visit to the Palomar Observatory

November 28, 2014

Palomar 2014 - London with the dome 1

London had the whole Thanksgiving week out of school, so I took some vacation days to spend it with him. On Monay we went to Anza-Borrego Desert State Park to camp and observe – more on that in the next post. We’d never been there before, and in planning our route I noticed that we’d go pretty close to Palomar Mountain. I asked London if he’d like to visit the observatory again, and he jumped at the chance. Our only previous visit, in September of 2012, had left a big impression on him.

Palomar 2014 - 18-inch model

The visitor’s center had gotten a major upgrade to its exhibits in the intervening two years. Out in the entrance lobby, a small display case showed this model and photo of the 18-inch Schmidt camera, which was the first operational telescope on Palomar Mountain. It entered service in 1936, a full 12 years before the 200-inch Hale telescope first opened its shutters in 1948. The 18-inch Schmidt had a long run – Carolyn and Eugene Shoemaker and David Levy were using it in 1993 to find and catalog near-Earth objects when they accidentally discovered Comet Shoemaker-Levy 9.

Palomar 2014 - 18-inch front

The 18-inch Schmidt has since been retired, and now it’s on display in the visitor center. This is a huge upgrade to the exhibits there – when we visited in 2012, all there was to see were the lighted plates along the walls of the room. Now the 18-inch Schmidt sits in a plexiglass island that is surrounded on all sides with photographs, signage, a touch-screen that shows short movies about the history of the observatory, and display cases with equipment used to operate the camera, including the hand-operated press that punched 6-inch circles of film.

Palomar 2014 - 18-inch back

Here’s the back end of the scope. As you can see, it has no eyepiece and no provision for one. Where an amateur Schmidt-Cassegrain telescope has its secondary mirror, the Schmidt camera had a piece of film (and maybe later a CCD?). On top is what looks to be a 6- or possibly 8-inch guidescope, which does have an eyepiece. Until the advent of computerized autoguiders, taking long-exposure photographs meant that an astronomer had to sit at the guidescope for hours, keeping the crosshairs centered on a guide star and tweaking the alignment of the telescope by hand. Sounds thrilling, eh? I wonder how much more productive professional astronomers are as a group, now that they don’t have to spend so many hours guiding telescopes.

Palomar 2014 - Hale dome with book

But of course the real attraction at Palomar Observatory is the 200-inch Hale telescope, which was the world’s largest fully-operational telescope for almost half a century. Astronomy books from before the early 90s talk about the Hale telescope in the same glowing tones reserved for the Hubble Space Telescope today. And for good reason – the 200-inch scope served roughly the same purpose as the HST and the twin Keck telescopes today. Until the space race of the following decades, the construction of the 200-inch telescope was probably the closest thing to a ‘megaproject’ in science and engineering. The story of how the telescope came to be is a decades-long saga of obsession, invention, science, engineering, and politics; if you’re interested in that story, I highly recommend The Perfect Machine: Building the Palomar Telescope by Ronald Florence. Here’s the 200-inch dome alongside its portrait from London’s Golden Book of Stars and Planets (1985 printing).

Palomar 2014 - London with Hale model

Famously, much of the design of the 200-inch scope came from the mind of amateur astronomer and amateur telescope maker Russell Porter, who built this scale model in the 1930s.

Palomar 2014 - Hale telescope

And here’s the scope itself. We didn’t get to go inside the dome and walk around the scope like we did last time. Those tours only run from April to October. But we were able to look in at the scope from an observation gallery.

Palomar 2014 - Hale concrete mirror blank

Outside the dome is this 200-inch concrete disk, which was used as a mass simulator to make sure the mechanical structure of the telescope worked before the actual mirror was installed. The mass blank has apparently been sitting out in the elements, right across the road from the dome, since 1948. It looks little worse for the wear, and it gives visitors a visceral sense of just how big a 200-inch mirror actually is.

Palomar 2014 - London with the dome 2

One last shot from this visit: London just off the path that leads from the visitor center to the dome. I had to take this one to replicate the picture below, from our last visit in 2012. It’s part of what is apparently now an ongoing series of pictures of London at different ages in front of the same telescope – see him with a replica of Galileo’s telescope here.

London at Palomar Mountain

Next up: crazy-dark skies at Anza-Borrego. Stay tuned.

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Observing Report: All-Arizona Star Party 2014

October 30, 2014

 

AASP 2014 - loaded for bear

If it’s late October or early November, it must be time for the All-Arizona Star Party. London and I headed out for it this past Saturday, Oct. 25. As in 2012, we were joined by the indefatigable Terry Nakazono. Here Terry and London pose for the obligatory “look how much crap we crammed into the car!” photo.

We arrived at the site about an hour before sunset, plenty of time to set up camp and chat with the neighbors. As usual, we set up not far from Darrell Spencer and AJ Crayon, but irritatingly I failed to get a picture with Darrell, my first such lapse.

AASP 2014 - setting up in the shade

When we arrived the sun was still well above the horizon and temperatures were in the mid-90s. London and I set up our scopes on the east side of the car so we could sit in the shade. Here London is tinkering with his AstroMedia 40mm “plumber’s telescope”, which we just built last week. More about that scope in a future post. The scope behind London was another AASP newcomer.

C80ED newly arrived 1600

This is my new Celestron C80ED. This scope originally retailed for about $500. Celestron donated all of the remaining stock of the spotting scope version to Astronomers Without Borders, and AWB sells it for $350 with free shipping. Vicki got me one for our anniversary last week (and I got her some leather boots–in both cases, the choice of gift was, ahem, heavily influenced by the recipient). The package arrived on Thursday about half an hour before the partial solar eclipse was to start, so I just had time to take this photo before I ran out the door to London’s school.

I got this scope because it filled a hole in my lineup. My Maks have sharp optics but can’t do wide fields. The TravelScope 70 can do wide fields but still has limitations, even after its tune-up. And the C102 is a wonderful scope but not exactly small, and although its chromatic aberration is minimal it is still there. I figured a small ED scope could be a grab-n-go that could deliver wide fields like the TS70, take magnification on planets and double stars like the Maks, in a more convenient and false-color-free package than the C102. Plus I’d just always wanted to try an ED scope. I was going to get an AstroTech AT72ED but they are out of stock and have been for ages. The C80ED offered a small but significant aperture boost for less dough, so I bit–or rather, encouraged Vicki to do so.

I was going to bring both the C102 and the C80ED, but as the date got closer I decided that what I really wanted to do was put the C80ED through its paces under those dark Arizona skies, and another scope would just be a distraction. I had briefly set up the C80ED on Friday night to make sure the scope didn’t have anything seriously wrong. It didn’t–in fact, it star-tests as well as any scope I’ve ever owned.

AASP 2014 - refractor city

Turns out we were all rolling with small refractors. From left to right they are the C80ED, London’s 60mm Meade refractor, Terry’s Orion Short-Tube 80, and London’s 20×50 Orion spotting scope (reviewed here). Terry had been going to bring a 4.5-inch reflector but the Clear Sky Chart said that conditions were iffy. Also, like me he had been interested to see how deep he could push a small refractor under dark skies.

Incidentally, after bringing my XT10 to the AASP in 2010 and 2012, I brought the Apex 127 last year and now an 80mm refractor this year. At this rate, in a couple more years I’ll be down to bringing just a finderscope. (I jest, but I have had a longstanding interest in going to a dark site with only the SV50 or GalileoScope to see how many things I could see with a small scope under dark skies–so far, greed for photons has always won out, so this project remains unattempted).

AASP 2014 - moon in C80ED

Our first target of the evening was the waxing crescent moon. I got a few shots with the iPhone shooting through the C80ED. Here’s the best one. All I did was crop it and flip it left to right–other than the orientation change, the actual pixels have not been tinkered with at all. Note the absence of false color. I also put the scope on Vega early in the evening and could not detect any false color–very impressive.

On the drive out, Terry asked me if I had any plans or goals for the evening. I did have a few:

  • above all, spend some time observing with London;
  • look at some familiar objects to get a feel for the scope;
  • track down some southern objects, since I’d be at a dark site with a clear and dark southern horizon;
  • to the extent that I could, test the scope on challenging targets like globular clusters and close double stars.

And that is more or less what I actually did.

A word about the sky conditions before I get into actual observations: they were not fantastic. Seeing was lousy the whole night, with the stars twinkling visibly all over the sky. Transparency was good in the early evening but around 9 or 10 a very light haze set in across the whole sky. It wasn’t ghastly, but it noticeably knocked down the contrast–where the Milky Way had blazed overhead at 8:00, by 10:00 it was just sort of there, visible but not nearly as prominent. In my notebook, I rated the seeing at 2 out of 5 and the transparency at 3 out of 5.

I only used four eyepieces for most of the night:

  • 24mm ES68, which in the C80ED gives a magnification of 25x and a true field of 2.7 degrees
  • 14mm ES82 (43x, 1.9*)
  • 8.8mm ES82 (68x, 1.2*)
  • 6mm Expanse (100x, 0.67*)

I did use a 32mm Plossl to drop the power down to 18.75x to see if Polaris could still be split (it couldn’t, but read on), and I used a Barlow once. Other than that, it was just these four, and out of these four, I used the 24mm and 8.8mm EPs significantly more than the other two. I had planned to use the 8-24mm Celestron zoom, but in testing the scope Friday night, I could tell that the Explore Scientific eyepieces were noticeably sharper. Good heavens, I think I’m turning into a refractor weenie and an eyepiece snob.

After the moon we visited Mars, but it was tiny and featureless and fairly burning in the bad seeing. Then I swung next door to Sagittarius and got my first surprise of the evening: the big glob, M22, was partially resolved even at 25x with the ES68! I love globs–they are one of my chief joys in observing with the XT10, and I expected them to be dim, featureless cottonballs in the C80ED. That I was getting partial resolution on one in a small scope at low power was pretty arresting. I had a quick look at M28, M8, and M24, and then helped London get his 60mm on target on M22, M28, and M8. London was interested in seeing a double star so we wheeled the scopes around and had a look at Mizar and Alcor. Then we looked at M13, M57, the Pleiades, the Double Cluster, and Stock 2 in his 60mm.

AASP 2014 - our camp

Highlights of the Evening: M13, M57, M27

After all that, London went to lie in the lounge chair and watch for shooting stars–he got 17 before he went to sleep around 10:30. I went on to M13, the Great Globular Cluster in Hercules, and had my socks knocked off. Like M22, it was partially resolved even at 25x, and much better at 68x and 100x. It wasn’t fully resolved, of course, and the XT10 will blow away the C80 on this or any other glob, but it was at least a ball of many, many stars and not just a fuzzy blob. Here’s one of the nice things about widefield eyepieces and short focal length scopes: you get huge fields even at reasonable magnifications. At 68x in the 8.8mm ES82, I could park M13 comfortably inside the field stop and watch it drift across the field of view for more than four minutes. Even at 100x in the 6mm Expanse, I could watch the cluster drift across the center of the field for a bit over two minutes. I commented to Terry that if I hadn’t had other things I wanted to see, I could have kept watching M13 all evening and been very happy.

Lyra was still pretty high overhead so I went there next. Epsilon Lyrae was shimmering in the bad seeing. It was elongated at 68x and almost split at 100x, but I had to Barlow it up to 200x to get a clean split. You may recall that under better conditions, the TravelScope 70 split the Double-Double at 133x, and I know that it is often split at well under 100x by high quality small refractors. So the high magnification required for the split here reflects more on the quality of the seeing than on the quality of the telescope. I’m looking forward to seeing how the C80ED performs on Epsilon Lyrae on a better night.

M13 was probably my favorite view of the night, but a close runner-up was M57, the Ring Nebula. It was clearly ring-like at 68x, but I liked it even better at 25x–the expansive 2.7-degree field of the ES68 showed the nebula nicely framed between Beta and Gamma Lyrae (the stars that mark the south end of the constellation stick-figure) and their attendant stars. It reminded me of the view of the Ring at 12.5x in the TravelScope 70 back in 2012, which is what got me into refractors in the first place.

After that I spent a few pleasant minutes rocking through the Lyra-Cygnus-Sagitta axis, observing M56, Albireo, Brocchi’s Coathanger (Cr 399), M71, and M27. Interestingly, the view of the M27 was very similar to the one I had through the C102 at the Salton Sea last year: I could not only see the “apple core” extensions, but also some of the “football” nebulosity between those extensions. That is a lot of nebulosity to pick up in an 80mm scope. I wonder what I could see on a night with better transparency.

By now it was about 8:50 and I knocked off the serious observing for a while. First I went to hang out with London, and while he watched for shooting stars, I used the 15×70 bins to sweep up many of the same summer showpieces I’d just seen in the telescope: M57, M56, Albireo, Cr 399, M71, M27, M13, the Double Cluster, some of the nice NGC open clusters in Cassiopeia. Then some folks from the other end of camp stopped by and we chatted for a while. Darrell came over and had a look at M13, and London and I went down to the center of camp to get some hot chocolate. When we got back, London sacked out. I had a quick look at M11 before it set, and tracked down the asterism DeLano 1 just to make sure it was still there. Then, at Terry’s suggestion, I tried M15, the big glob off the nose of Pegasus. Here are my unedited notes:

M15 – tough nut to crack. Starting to look grainy at 100x. Also pretty grainy at 68x in 8.8mm ES82. Even though it only gives about 2/3 the magnification of the 6mm Expanse, I think the 8.8mm ES82 shows almost as much. It’s just a superior piece of glass. Another ES82 or 68 in the 3-5mm range should be priority.

Now, this idea that the 6mm Expanse is maybe not 100% awesome–hold onto that thought, we’ll revisit it at the end of the evening.

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Go South, Young Man

Ever since my incredible Salton Sea run with David DeLano last fall, I have been painfully aware of how much I’ve neglected the southern sky. So from 10:45 to 12:30, that’s where I went. My first southern target was NGC 7293, the Helix Nebula. It was dead easy to see once I got there, but it took me an unusual amount of faffing about to get on target. I was using the 6×30 straight-through correct-image finder that came with the C80ED. I’m normally a RACI man so using a straight-through finder took some getting used to. But I kinda like it, now that I have the hang of it.

After that it was onto some galaxies and planetaries: NGCs 55, 300, 288, 253, 247, 246, 720, and 779. NGC 288 and NGC 253 were nicely framed in the same field. NGC 288 is a globular cluster circling our own Milky Way galaxy, about 29,000 light years away, whereas NGC 253, the Silver Coin galaxy, is 11.4 million light years away, almost 400 times farther, and rivals our own Milky Way in size. So that pair has a bit of the M97/M108 ‘odd couple’ thing going on.

The not-quite-edge-on galaxies NGC 720 and NGC 779 were my only new objects for the evening. Both of them are on the Herschel 400 list, and bring my H400 tally to 175. I am starting to wonder if I will ever finish the Herschels–the only new ones I’ve notched in the past couple of years have been bagged at the All-Arizona Star Party. I gotta get out in the spring more. I’ve just about exhausted the fall Herschels, but there are hundreds of spring galaxies to observe in Ursa Major and the Virgo-Coma Cluster.

C80ED AASP 2014 2000

Orion and Points North

After almost two hours of faint fuzzies, I was ready for a change of pace. I turned east, toward Orion. The view was pretty great–the Trapezium was split into four components at only 25x, and the nebulosity seemed to go on forever. And yet, the subtle gradations in the nebulosity did not seem as pronounced as I had observed on other nights. Terry noticed the same thing observing Orion through his ST80. He thinks that the poor transparency was leaching some of the contrast out of the view, and I am inclined to agree.

Without a doubt, the strangest observation of the night was of NGC 1980, the field of nebulosity around Iota Orionis. When I looked right at the nebula, it was steady, but when I looked back at M42/M43, NGC 1980 would flicker in my averted vision like a bad fluorescent bulb. At first I thought maybe it was just my eyes, but I called Terry over and he reported seeing the same effect.

Now, I don’t think that the nebula was actually flickering. I suspect that through some quirk of eye/visual system physiology, it only seemed to flicker in averted vision.

Just to rule out the obvious distractors: we were parked on the very east end of the airstrip so there was probably no-one between us and Phoenix. Neither of us were using flashlights or any electrical gear at all while we were observing in Orion. Our nearest neighbors were about 50 yards to the NW and SW, and they’d all turned in for the night. So I’m about as certain as I can be that it wasn’t some terrestrial source that just happened to be shining into the eyepiece or objective lens. Also, we only noticed the flickering on NGC 1980, and not on the extended “wings” of nebulosity from M42, which were of similar brightness at their extremities.

Has anyone else seen anything like this, either for NGC 1980 or other DSOs? If so, I’d love to hear about it–the comment thread is open.

After Orion’s Sword I bounced around a few northern Messiers–M78, M1, M35 with NGC 2158 just starting to resolve behind it, M81 and M82 in the same field, and M97 and M108 in their own field. Midway through that tour I stopped to split Polaris. It was continuously split at 24x in the 24mm ES82, not split at 18.75x in the 32mm Plossl. This illustrates just how seeing-dependent double star splitting is–Friday night from my driveway, the seeing was even worse, and that evening Polaris was not continuously split at 25x, but it was a 43x in the 14mm ES82, and even at 28.5x in the 21mm Stratus. As indicated above, the seeing out in Arizona Saturday night was not awesome. One of my quests with the C80ED is to see how low I can go, magnification-wise, and still get clean splits on some of the classic double stars. Watch this space.

M97 and M108 were my last DSOs of the evening. After that I turned to Jupiter, and even at 68x I could see at least 4 belts. The Galilean moons were spaced about evenly, two on each side of the planet. Terry and I compared views of the planet through the C80ED and his ST80. We could get similar magnifications with our favorite short eyepieces: the 8.8mm ES82 gave 68x in the C80ED (FL = 600mm), and the 6mm Expanse gave 67x in the ST80 (FL = 400mm). So how did the scopes compare? Well, obviously the ST80 was throwing up a lot of false color, but I could detect the same four belts that I could in the C80ED, albeit not quite as crisply. More informative was the comparison of eyepieces. Terry had a 6mm Expanse clone from AgenaAstro.com. While were swapping all of these eyepieces between the two scopes–the 8.8 ES82, the 6mm Expanse, and the 6mm Expanse clone–I noticed something I had never spotted before: the 6mm Expanse threw up a huge circle of glare around Jupiter. Perfectly circular, like a lens flare, centered on Jupiter, and spanning out to the outermost moon on each side. The glare circle was there in the 6mm Expanse in both scopes. It was not there in either scope in the ES82, nor in the AgenaAstro Expanse clone. These are the Agena Enhanced Wide Angle (EWA) 6mm, which goes for $45 (you can find it here), and the 6mm Orion Expanse, list price $68, street about $59. So if you’re in the market for a 66-degree EP, you can save about 25% and get noticeably better performance from the Agena version. I’m tempted to get one myself, and hock the Orion EP. Until now, the 6mm Expanse has been one of my most-used EPs, but now that I can see its faults…like I said, eyepiece snobbery is taking hold.

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Settling Up

After one last look at Jupiter in the ES82 at 3:00 AM, I shut down and went to bed. The next morning, London and I went on our customary “bone hike”, and we did find several bones, including a couple of cow limb bones, and the jackrabbit lower jaw shown in the photo. More exciting were the Western diamondback rattlesnake and the horned lizard that we found.

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My final tally for the evening was 45 telescopic objects:

  • 2 planets (Mars and Jupiter)
  • 22 Messiers
  • 13 other NGCs
  • 2 asterisms (Brocchi’s Coathanger, DeLano 1)
  • 1 other catalogued DSO (Stock 2)
  • 5 double/multiple stars (Mizar/Alcor, Albireo, Epsilon Lyrae, Trapezium, Polaris)

…plus a couple of meteors.

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Irritatingly, I realized later that I had completely missed out on some real gems. I never once pointed the scope at the Andromeda galaxy or its satellites–detail in M31 would have been a good test of the C80’s optics. And I skipped the nice open clusters in Auriga–M36, M37, and M38–which maybe more than any other set of clusters give that “diamonds on black velvet” feeling in a sharp telescope. We set up early enough that I could have rocked through all of the Sagittarius Messiers instead of the handful I actually saw, but I deliberately traded that time away to help London find some things, so I don’t feel bad about that particular omission. The others are a bit galling.

Even with those omissions, I still met all of the goals that I had set for myself: I got in some good observing time with London, I had fun touring the southern skies, even if most of the things I saw there were revisits, and I both got a feel for how the scope performed on average targets, and got to push it on some challenging ones. The biggest revelation to me was that an 80mm scope would start to crack open some of the bigger globs. M13 and M22 didn’t just look good, they looked stunning. I wish I was observing them right now.

In sum, a great night of stargazing, and a pretty thorough field test for the C80ED. I think I am going to have a LOT of fun with this scope.

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Observing Report: a semi-cloudy night at Joshua Tree

October 8, 2012

My scope at Joshua Tree Saturday night. Clockwise around the scope are the bright star Capella just in front, the constellation Perseus (12:00), the Pleiades (2:00), the Hyades (V-shaped arrow of stars directly oppose Capella), and Jupiter (4:00). Photo by Kevin Zhao.

Saturday evening I was at Joshua Tree. My summer anatomy students invited London and me along to the Indian Cove campground. I didn’t have room in the car for the big gun so I took my 5” Mak, which is what it’s for—times when I need a decent amount of aperture in a small package. That was no loss: the sky was striped with high, thin clouds all night and never really cleared out. We got decent views of a few things, but the 10” would have been wasted. We used the Mak to look at the Double Cluster and Jupiter. In moments of steady seeing there were quite a few cloud belts showing, and all four Galilean moons were lined up on one side of the planet, which was pretty cool. London brought along his AstroScan and we used it to look at extended objects like the Pleiades and the Andromeda galaxy.

iPhone panorama by Chad Claus. Click for the big version!

The clouds might have made for lousy telescopic views but they made for gorgeous naked-eye skywatching. At sunset the whole sky was striped with light from one horizon to the other.

Here’s another view, actually taken by me for a change. This is the unprocessed raw image, direct from my Coolpix 4500.

Moon halo photo by Kevin Zhao. Jupiter is inside the ring at 1:00, and the Pleiades are outside at about the same angle.

When the moon rose around 11:30, it was surrounded by a ring of faint light. I thought it was a moonbow, but that’s something different. The ring we saw around the moon is called a 22-degree halo and apparently has no other or more poetic name. That’s a shame. In the early morning, when the moon had gotten well above the horizon, it was surrounded by a complete circular halo with radiating clouds on either side. That was worth the clouds. I’ve been under wonderfully clear desert skies many times, but I’ve never seen a moon halo quite like that. For once, I think the clouds were worth it.

Update: There wasn’t just a moon halo, there was also a sun halo Saturday afternoon. Agnes Kwon captured it in pixels. Witness:

Many thanks to Agnes, Chad, and Kevin for letting me illustrate my post with their awesome photos!

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Observing Report: SkyScanning in Oregon

October 2, 2012

I was up in Oregon last week to visit my university’s second campus in Lebanon. It was a kill-many-birds-with-one-stone type trip: in addition to day-job work in Lebanon on the weekdays, I got in a productive meeting about a joint project with a paleontological colleague who lives nearby, and–the point of this post–last Wednesday night I got to go stargazing with frequent commenter Doug Rennie.

Doug lives up by Portland and I was staying in Albany, so we needed someplace in between with reasonably dark skies. We settled on Baskett Slough Wildlife Refuge, just north of Dallas, OR. We met in Dallas for dinner and then drove out to the slough.

I had along a new-ish pair of Nikon Action 10×50 binoculars that I picked up this summer and haven’t used much. Doug brought his Celestron SkyMaster 15x70s–the same model I have and love–and his Orion SkyScanner 100 tabletop telescope.

Neither of us really knew what to expect in terms of sky quality. The waxing gibbous moon was only three days shy of full, and I was seriously concerned that we’d get “mooned out” and not be able to observe anything in the deep sky.

This brings up the interesting question of how much moonlight it takes to significantly degrade the night sky. I’ll write a full post about it someday, but for now it is enough to note that the brightness of the moon increases exponentially on the run up to opposition (full moon), and decreases exponentially after full moon. For explanations of why that is, check out this graph and this tutorial and read up on opposition surge and heiligenschein. The upshot is that three days shy of full the moon is only perhaps a quarter as bright as it is at full moon, and happily we were able to see quite a bit.

I didn’t know that when we started out, though, but I knew that we wouldn’t see anything if we didn’t try. Ursa Major was opposite the moon, getting closer to the horizon, and with it some of the best and brightest galaxies in the sky. I spent a few minutes faffing around and managed to get M81 in the field of view. It was dim, but it was there, and our observing run was underway.

Some hazy clouds were skirting the northern horizon, and I was worried they might come south and ruin things for us. Also, after the frustrating chase and unimpressive view of M81 we needed a win, so our next target was the Double Cluster, NGC 869 and 884. They were spectacular–two brilliant knots of stars in the rich Milky Way starfields of northern Perseus.

After that we hit some other summer and fall “best of” objects, including the Andromeda galaxy (M31), the Great Glob in Hercules (M13), the Ring Nebula (M57), and the Dumbbell Nebula (M27). Next to M31 we caught the brighter and more compact of its two Messier satellite galaxies, M32. I don’t know if M110 would have been visible or not. It’s a tougher catch, especially under less-than-perfect skies, and I didn’t waste any time looking for it.

M13 was an easy catch, and we kept running up the magnification to see if we could get it to resolve at all. Doug’s 6mm Expanse yielded 67x and, we thought, some tantalizing hints of detail. We Barlowed it up to 133x and the cluster took on the slightly grainy texture that is often the most resolution one can get in a small scope. We also tried lots of magnifications on the two planetary nebula, M57 and M27. We could only glimpse in averted vision the slightly darker center that makes the Ring a ring, and the Dumbbell showed the barest hint of its bilobed structure.

After that we turned back north and plied the starry Milky Way between Cassiopeia and Perseus. Cassiopeia is just lousy with asterisms and open clusters; the only ones we bothered to identify were M103 and nearby NGC 663, which is bigger and brighter.

A highlight of the evening was sweeping the Alpha Persei Association with binoculars. It’s really seen best this way–very few telescopes have a wide enough field of  view to show more than a small part of it. I once read a description of this big, close cluster–variously catalogued as Melotte 20 and Collinder 39–as a “vast wonderland of far-flung suns”, and I can’t look at it without those words coming to mind.

Since Perseus was now a good way up the sky I thought it would be worthwhile to track down the open cluster M34. I’m glad we did. When Doug looked at it he said, “I know this cluster–I’ve drawn it!” And he had–his sketchbook recorded the fingerprint-specific arrangement of stars that make up the cluster. I was most impressed by this–by the drawing and his visual memory both.

At this point we were winding down a bit and just scanning around with binos, taking things as they came. Halfway down the western sky I found the brilliant blue-white double star 16/17 Draconis. By this point Doug’s green laser pointer was fading a bit from cold and overuse, but with some yammering and gesticulating on my part–and much patience and good humor on his–we were able to get both pair of binos on target. That really is a gorgeous double, and just wide enough to be clearly split in low-power binoculars. I recommend it.

Our last stop of the night was the Pleiades, which had just climbed over the northeastern horizon. They were stunning, as always. That gave us a total of nine Messier objects, three non-Messier NGCs (663, 869, and 884), another big open cluster (the Alpha Persei Cluster), and a double star. So, 14 objects in all, which is pretty good for a two-hour session under any conditions.

Using the SkyScanner was a revelation. I had taken a few brief peeks through Terry Nakazono’s SkyScanner on our Baldy runs, and been impressed, but I’d never gotten to just pick one up and freewheel. And “freewheel” is a pretty good description of what we were doing. The scope is light enough that you don’t think twice about just picking up one-handed and moving it wherever you need it. At the same time, four inches is a lot of aperture, and I was consistently impressed by how much the little scope could do, both in terms of light-grasp and resolution. Doug must have collimated it to within an inch of its life, because the image was still good at 133x–a real achievement in any small, fast Newtonian. Finally, I didn’t notice any issues with the focuser. This is one of my pet peeves. Fast scopes have steep light cones and it takes a precise focuser to consistently hit focus without going past in either direction. One of the things that drove me crazy about the Celestron FirstScope was the lousy focuser, which consistently overshot focus. So when I say the focuser on the SkyScanner didn’t draw attention to itself, that’s a good thing. I’m sure that like all consumer scopes there’s some sample-to-sample variation with the SkyScanner, and Doug’s might be an unusually fine example, but so far both of the SkyScanners I’ve gotten to use have impressed me. I think I’ll get one for the Suburban Messier Project, which is on hold until it cools off some–it was 107 here today. In October!

Oh, and speaking of the Suburban Messier Project, I was most impressed by the quality of Doug’s sketches, and by the fact that, having sketched something once, he could recognize it at the eyepiece later without knowing in advance what it was. I’d like to have that level of familiarity with these objects, and I intend to get it–by sketching them. Stay tuned.

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Guest post: The “First” Great Telescope: the Great Dorpat Refractor in Tartu’s Old Observatory

October 1, 2012

Here’s another guest post by Terry Nakazono (his first is here). Enjoy!

(All pictures, except for the image of F.G.W. Struve, were taken by the author)

In a few posts (and one Cloudy Nights article), Matt made mention of getting his start in observational astronomy after a visit to Lick Observatory in San Jose, California and looking through the Great Lick Refractor.

The term “Great Refractor” refers to an achromatic refracting refractor that is the largest in a region, or in the world. When it was completed in 1888, the Lick refractor was the biggest (36-inch lens) in the world. Hence the term the “Great Lick Refractor”.Earlier in April this year, I made a visit to the Old Tartu Observatory in Tartu (Estonia), built between the years 1808-1810 and now a museum.

This observatory houses the first “Great Refractor” – the Great Dorpat Refractor (Dorpat is the old German name for Tartu), built by the noted German optician Joseph Fraunhofer in 1824 (also known as the Fraunhofer Refractor). This telescope was the forerunner of the Lick and other large refractors built in the 19th and 20th centuries.

This 9.6 inch (24cm) achromat with a focal ratio of 16.6 was the largest and best refractor in the world for many years. The lens had a light-gathering capacity equal to a reflector of that era having twice the aperture of this refractor. This was also the first telescope to use a German equatorial mount, with a precision clock drive that allowed objects to be tracked automatically.

The man who ordered this telescope from Fraunhofer was Friedrich Georg Wilhelm Struve, the director of the observatory from 1820-1839.

His most famous observations with this refractor included a massive survey of double stars (whereby he published two double star catalogs), the measurement of the parallax of Vega in 1837, measurements of the diameters of Jupiter’s 4 largest satellites in 1826 (which turned out to be the most accurate for the next century), and Halley’s comet in 1835, where he measured the dimensions of the tail and was able to see the nucleus of the comet. On the observatory grounds is a monument to Struve.

On display at the observatory are many other instruments used by Struve and others. One is the Dollond transit instrument (purchased in 1807), used to determine exact astronomical coordinates.

Another instrument used to measure the position of stars was the Reichenback-Ertel Meridian Circle (purchased in 1822).

The Troughton telescope (purchased in 1807) was a 3.5 inch achromat that was Struve’s main observational instrument before the Fraunhofer refractor.

But the most fascinating item on display (besides the Fraunhofer scope) is the Herschel 7-foot refractor, bought in 1806. Herschel made 200 of these 7-foot scopes between 1778 and 1820, out of which only 21 have survived today. It was with one of these scopes that he discovered Uranus in 1781. The aperture of the Herschel 7-foot scope was 160mm, or 6.3 inches. Reflectors of that era were made of speculum metal, which tarnished easily and reflected only 66% of the light that hit it. During the pre-Fraunhofer refractor days, it was easier for Struve to use the Troughton 3.5 inch refractor as his main observing scope, since it was much more portable and probably matched, if not exceeded, the light-gathering capability of the Herschel reflector. Consequently, the Herschel scope was used mainly for observing the occultation of stars by the Moon.

There were two Tartu University students working in the observatory (one worked the front desk and the other was letting visitors in and out of rooms]. Unfortunately, they were neither astronomy nor science majors and could not answer any of my questions regarding the Fraunhofer and other instruments.

Here is a picture of the dome of the observatory at night – you can see the moon and Venus next to it.

This next picture shows my Galileoscope 2-inch achromat refractor in front of the entrance to the observatory.

Looking forward to visiting other historic observatories, including the ones closer to home (e.g. Lick, Mt. Wilson, Palomar).