I was maintaining the documentation of our tensegrity shade structures on my website (bweebweebwee) for a while, but have now retired that site.
These may eventually end up somewhere else, but this blog seems like a perfectly fine place for the time being. So here are the original instructions, over ten years old now. I will append some newer notes below.
Camp Elsewhere’s Tensegrity Shade Structures
The idea behind a tensegrity structure is that the solid members are loaded under pure compression with ropes or cables providing all the tension. This allows them to be very strong while using a minimum amount of materials. The first of these tensegrity shade structures was built and used at Burning Man in 1998. In 1999, we redesigned them and made a bunch more. They work well for Burning Man because they are:
1) cheap to build,
2) fairly easy to transport,
3) fast and easy to set up,
4) nice and cool with maximum airflow, and
5) best of all for the playa, they are pretty much indestructible.
A bonus is that they are more minimalist, unique, and, in our humble opinion, more attractive than the sea of white pvc and blue tarp shanty structures which blanket Black Rock City. The downsides are:
1) they have a fairly big footprint for the amount of shade they provide so they may not work if you are camping in a crowded area.
2) as currently used they are not intended to block the wind or rain at all, they are for shade when it is nice and hot, although with the addition of more walls, they could provide some wind protection, and
3) idiots trip on ropes.
You can make structures like these with all sorts of variations in size and geometry which will all work just fine. Here is what you need to buy or steal to build one like ours.
Three 8 foot beams. These can be any material that is light, stiff, and can be easily drilled. We used cheap 2x3 lumber, but aluminum, steel or pvc pipe would probably work provided they are stiff and strong enough. Your mileage may vary.
A whole crapload of rope, at least 200 feet and more like 250 feet, depending on how efficient you are with cutting and tying knots. We use truck rope, that black and orange stuff, because it is cheap, very very strong, is weather resistant, and does not stretch. Downside is that it does not knot very easily. You can get them in 100 foot rolls at hardware stores. I usually use 1/2” because I like overkill, but you can probably get away with smaller. Do not burn this stuff, at least not anywhere near me, as it is plastic and will give off nasty fumes which I do not want to breathe. Any other rope that does not stretch too much should work fine. Steel cable would kick ass. One of our people made a structure using detachable rope hardware which made set up and take down a snap. Go nuts.
6 pieces of rebar. At least 2 feet long and 3/8” diameter and I personally like 3 ft x 1/2 inch cuz that’s the kind of guy I am. Do not attempt to put up one of these structures with tent stakes or even with wimpy rebar. You will end up being a sad panda.
Fabric for shade - We used white cotton cloth custom sewn for our structures with many, many, many grommets. One triangular piece for the top and one rectangular piece for a wall which could be moved around. Our fabric was pretty sturdy in strong wind, but we always took it down during major windstorms. If you intend to leave your shade material mounted in major storms then you should think about some very heavy duty grommets or webbing or other suitably strong attachment method. Recently, we have been using old sails lying over the top of our structures and staked directly into the ground. This is very strong and provides a lot of shade and decent wind protection, as well.
That’s it - that’s all the materials you need!
Tools you will need to build
Drill and drill bits
Maybe a lighter to melt off plastic rope ends.
A couple of big pieces of pipe, about 3 feet long each and big enough to slip over your rebar.
Tools you will need to set up
Sledgehammer - everyone should own at least one big ass sledgehammer.
How to make the thing
I am not going to go through how to tie knots and loops and such because I don’t know much about this myself and there is no one correct way to tie these things together. Do it however it works for you. I find that figure-8 knots work well for the permanent loops at the ends of the anchoring ropes. If you don’t know how to make a figure 8 knot ask a friend who rockclimbs.
Step 1: Basically, just drill some holes sideways though the beam at the top and bottom big enough for your rope to go through. I used one hole at the bottom and two at the top (one for the top rope and one for the anchor ropes). The first structure used 1 inch eye screws in the ends but this is just something else to fail. Holes are better. Lookee at Diagram 1
Step 2: Then lay the beams out on the ground and tie it all together with loops at the end of the anchoring ropes. You may want to make a few of the anchoring ropes with adjustable loops/knots (e.g. a trucker’s hitch) to make adjustments to the structure. Lookee at Diagram 2
There are only two different lengths of rope you need to remember.
Top ropes = 14 feet
Anchoring ropes = 10 feet 7 inches
These lengths are based on 8 foot beams, a 14 foot radius hexagon footprint, and the beams ending up at 60 degrees from horizontal and are the theoretical point to point distances in the final geometry. In practice they end up being a little shorter because the holes in the beams where the ropes are attached are not at the exact ends. As with every thing else, you can vary the geometry however you like, but found that these measurements provide a nice symmetrical small to medium sized structure that can fit about a half dozen people under it comfortably.
Basically, the tops of the three beams are connected in a triangle 14 feet on a side. And each of the three beams has 4 anchoring ropes coming off of it, two from the top and two from the bottom with a loop at the end of each.
Step 3: Bend your rebar. Stick a rebar into a pipe with about 10 inches of rebar protruding. Slip the other pipe over the protruding rebar leaving a few inches of rebar visible. Bend the top 6 inches back so it ends up looking like a candy cane. With 1/2 inch rebar this will not be easy. Have some friends stand on the pipe covering the long section of rebar or stick it in a huge vice. Do not hurt yourself doing this and do not sue me. Lookee at Diagram 3
Setting Up 1: Precise Method (need only 2 people, maybe 1 if you are desperate and have no friends)
1. Lay out a hexagon on the ground which is 14 feet in radius, 14 feet on a side. You can do this more easily by tying yourself a piece of rope with two loops 14 feet apart and use it with a couple of pieces of rebar like a big compass.
a) mark a center and draw a big 14’ radius circle
b) pick a starting point on the circle and then use the 14’ rope to find your other points along the hexagon. Lookee at Diagram 4
2. Hammer in your rebar at the six points but not all the way in - allow enough room to slip your anchor loops onto the candy cane sections.
3. Lay out your beams with tops in toward the center of the circle and bottoms out
4. Have a friend hold up one of the beams in close to its final position and attach its anchor loops and hammer the 2 rebar most of the way in (leave a little bit out in case you need to change something). Your other two beams will be all over the place now.
5. Have your pal hold up the 2nd beam and attach and hammer in the ropes from this one. Things will look a bit better now.
6. Continue on and do the 3rd beam.
7. If everything looks good. Hammer the rebar in so they are flush with the ground.
8. There will probably be some looseness in the structure. Adjust the knots so that everything is taut. There should be very little to no slack in any of the ropes. The structure should be rock solid now.
9. Attach whatever shade material you have fashioned.
Setting Up 2: Easy Method (need 4 people - works remarkably well)
1. Get three people to hold up the beams in more or less the final configuration (leaning away from each other about 60 deg from horizontal with the top triangle as taut as possible
2. Run around and hammer the 6 rebars into the ground, anchoring the 12 anchor ropes to the ground so that the structure is nice and taut and not too crooked.
3. Adjust or tighten any of the individual ropes as needed.
4. Attach shade material.
It’s a good idea to practice putting one up near your home.
Here are pics from Camp Elsewhere - Burning Man 1999 showing the shade structures under construction and being used.
Logan finishes her structure (layout of beams and ropes are shown clearly and labeled)
A bare structure in the background (ignore the choad blocking the view)
Blowin in the wind (and Tammy with her birds)
The structures are strong enough to support a hammock.
Big shout outs to Elsewhere campers Layla, Logan, and Jila who put a lot of time and effort into the design and building of these structures.
Big ups to Jon Luini, Logan, jD, and Lettuce for providing all the photos. Diagrams are by me.
2014 Updated notes/comments:
The scholarly observer will note that these structures are not pure tensegrity structures from a mathematical standpoint because they are not freestanding—they rely on attachment to the ground. I find that precise definition to be less relevant when discussing architectural structures. After all, bridges and buildings are always assumed to have at least one fixed point. And these structures do satisfy what I consider to be the key quality of tensegrity—the rigid members are loaded under pure compression, with no torsion.
The most apt description I have seen of ground-dependent structures like these are “open tensegrity structures” as opposed to “closed” or self contained ones.
Since 2000, the structures have remained exactly the same. In fact, most of the original structures are still intact and in occasional use. We stopped going to Burning Man years ago, but continued to camp on the Black Rock Desert for many years after.
The one thing that changed drastically was the covering materials that we used.
For a few years we experimented with using old sails. These were indestructible and provided tons of shade, but they were overkill—extremely heavy and difficult to transport.
We also tried different types of woven materials and attachment methods.
The final design I settled on and still use is heavy canvas. I bought a bunch of 12 oz. canvas 12’x15’ drop cloths (available at any hardware store) and arrange them in various configurations on the ropes.
The attachment points are 1” nylon webbing sewn into the corners and edges with heavy duty thread. These points are then attached to the ropes with heavy duty reuseable cable ties (these must be the beefy ones, like 100 lb tensile strength) and roped to additional ground anchor points.
If you look at the high-res original, you will see that the black nylon makes a ‘U’ shape. I put one piece along the edge of the canvas, which is stitched down at both ends with a 1-inch crossed box like you normally see with nylon webbing. The middle is free and is where the cable tie or rope goes through. Then over each end I sew in two additional pieces that extend in from the edge. The idea is to distribute the load away from the edge of the fabric which is where it will always tear first.
At the corners, I likewise sew several pieces of cloth extending inward to distribute the load. I also add piece a perpendicular piece to secure the edges and keep them from tearing in that direction. This can also be done with one very long piece folded in half to form the loop and then both “legs” sewn into the fabric parallel to each other and diagonally in from the corner.
Heck, this is hard to explain. Just to show you how much I care, I went downstairs and pulled out a shade cloth to take these pics of the corner and edge attachment points.
Corner attachment point — you can see there’s actually some fraying/tearing of the canvas at the corner, but it stops right there at the nylon webbing.
In the sidebar are some ways to contact me if you have questions.
I came across the Kickstarter for the Black Rock Observatory to build a small observatory at Burning Man with a 20” Dobsonian telescope, science exhibits, and some solar scopes.
I am all for astronomy and science outreach and the Black Rock Desert is an amazing dark sky location, but there’s a few issues here.
- If you’ve been to Burning Man, you know that the dust, smoke, and light pollution can be significant. I hope they don’t depend on seeing much in the way of nebulae or galaxies, at least from Thursday on.
- Jupiter will set before 7 pm.
- Saturn and Mars will set before 11 pm.
Uh oh: “Dust!? We got this covered. Our telescope will resolve the Galilean Moons of Jupiter, the Rings of Saturn and 5 of its moons, Martian polar ice caps and the outer planets. We’ll be exploring faint galaxies many thousands of times too dim to view with the naked eye and distant nebula…”
On the plus side:
- They’ll be on the “outer playa” which I assume means near the wind fence. So depending on the direction of the wind, the sky facing away from the city may be clear. I hope they can put themselves south of the city and the Man if they plan on observing Sagittarius (M8 and M20 are mentioned on the project website).
- At least the moon will be setting pretty early those days.
- The nice thing about that observatory is that it will block the winds, which are hell on image stability out there, even with a small telescope.
- The solar scopes should be really cool (provided the daytime dust cooperates).
- This would be fantastic to have out there when Burning Man is not happening, perhaps during 4th of July (which I already stopped attending because it’s too crowded now).
- This is a great way to get people to buy you a 20” dob.
I’m not saying that this is not a great project, just that I hope they temper their expectations about what people will be able to observe through their telescope.
I may back it at $25 and get a cool patch.
Part two of my trip to New Mexico… (part 1 here)
I woke up mid-afternoon, Friday, March 27, prepared for my day, and then went to scope out the best observing sites. I drove through downtown Glenwood, which took about 30 seconds, and visited a local ranger station to get the lay of the land.
My Airbnb host had told me about her friend’s amazing project to establish a dedicated astronomy campsite within the Gila National Forest:
The campsite’s precise location is a bit difficult to find on the website, but it is located at (according to Google):
But how to get there is the trick. Even the ranger was unclear about where to turn off from the highway (understandable, given that the campsite is still under construction and not featured on any official maps).
The turn off is located at:
Basically, just go north up US 180 from Glenwood and turn right at 13.9 miles onto a dirt road that has a cattle guard. Google Maps directions.
The site itself is just a 5 minute drive straight down the dirt road.
The site is currently cleared and open for use, but without any facilities. The plan is to add pit toilets and concrete pads for telescopes. The site is amazing, with views nearly to the horizon in 360° and is completely shielded from the highway by low rolling hills. There is a tiny bit of skyglow to the south, probably from Silver City, but it is barely noticeable. You really have to look for it.
Here’s some friendly cows. They were blocking the road when I checked out the site during the day, but courteously got out of my way.
The view spanning north to southeast.
The view spanning from south to northwest.
I returned a little after sunset at 7:30 and was ready to start observing by the end of astronomical twilight. It was another incredible night. Clear except for some small scattered clouds in the evening that disappeared by midnight.
Even though it was slightly warmer than the night before, around 40° F, it felt much colder due to windchill. It wasn’t terribly gusty and didn’t interfere with the stability of my scope, but the slight wind was enough to suck any warmth right out of me. I had to retreat to my car a couple of times to eat, hydrate, and thaw out by running the engine and heat full blast (with a window cracked, of course). Thank goodness the little Hyundai had heated seats.
That night, I observed the following:
Yes, that is a lot of Messier objects.
With the clearer horizon, the Milky Way was an even more incredible sight than the night before. After I had completed my above list of targets for the night, I went back to observe some of the finer sights, such as the incredibly rich areas of Sagittarius and Scorpius. I spent many minutes observing M42 Orion Nebula, which I can do at home, but in such perfect conditions, it popped with detail and texture like I had never seen through visual observation. And then I spent a lot of time just leaning back against the side of the car staring agog at the enormous Milky Way.
One exciting thing happened. In the wee hours, probably sometime between 2 and 4 am. I heard a few isolated howls and then a whole chorus of them, echoing all around me. Yikes!
Now this is not the first time I’ve encountered howling coyotes while out observing in the night. It always excites some primal alarm bells. But on those occasions, I hadn’t been that far out from civilization and other people. Rationally, I knew that coyotes were harmless. Still, there I was, alone, with the closest human being probably 10 miles away. I was about a half mile from the highway as the crow flies, and about a mile by the road. My host sort of new where I was. Sort of. I immediately sized up my situation. Was there anything I could wield as a weapon? My telescope and tripod? Nope, too heavy. Maybe my telescope case could be a decent shield. Nah. I figured the best bet would be retreat. I made sure that the car door closest to me was unlocked. Also? Please don’t be wolves. Please don’t be wolves.
In retrospect, I had on a million layers of clothes, a brown jacket and dark red pants so I probably looked like a bear. Not exactly something other predators would mess with.
I stayed out again until about 5 am, then packed up using only red lights to preserve my night vision. I spent a last few minutes enjoying the Milky Way before heading out. (I will say that after spending 8-9 hours with fully dark-adapted vision, car headlights are incredibly bright.)
On the drive back up the road to the highway, I came across tons of jackrabbits. So I knew what those coyotes or wolves were so excited about.
I found some bluegrass guitar on the radio for the drive back to my cabin and was in bed before the sun came up around 7. Another epic night!
Here’s the skinny (especially for Northern California):
- The peak time for the meteor shower is projected to be 6:00 - 8:00 AM UTC on May 24, 2014.
- For Pacific Daylight time this is FRIDAY NIGHT, May 23rd, 11:00 PM to 1:00 AM Saturday.
- Look almost due north, slightly left of and below Polaris. The radiant point (where meteor trails originate) is projected to be in the constellation Camelopardalis at RA=122.8°, Dec=+79.0° (source: arXiv:1311.0235).
- The source of the meteors is the comet 209P/LINEAR.
- The moon will set in the afternoon and not rise until 3:21 AM. This is good!
I don’t have my Stellarium in front of me, but I will post a diagram with the projected radiant point before Friday.
EDIT—here’s a diagram showing the approximate radiant point at 11:00 pm on Friday, May 23rd from San Francisco. Created with Stellarium planetarium software.
ASTRONOMY RIDDLE FOR THE DAY
The word camelopardalis is the Latin combination of the Greek words for camel and leopard, describing an animal that looks like a combination of both. The constellation is named for its resemblance to this animal.
What is the animal that looks like a combination of a camel and a leopard?
I had a fortuitous opportunity to take a memorable astronomy trip this past spring. I was due in Phoenix, Arizona for a professional conference at the beginning of April and I’d often heard that the southwestern United States has some of the best dark skies in the world. Scanning the various dark sky maps and astronomy sites, I realized that Phoenix was about half a day’s drive away from several excellent dark sky areas including northeast Arizona, Arizona Sky Village in southeast Arizona, and western New Mexico.
Likewise, the weekend prior to my conference would have perfect timing in terms of a total absence of moonlight. In fact, the All-Arizona Messier Marathon was scheduled for that weekend just a few hours west of Phoenix.
After looking at all the options, I decided to rent a car and drive to the Gila National Forest in western New Mexico. This seemed like a rare opportunity to observe under real black skies with ideal moon conditions. So I booked three nights at an Airbnb guest house in Glenwood, New Mexico. Glenwood is a tiny town at 4,760 feet elevation at the edge of a black zone in most dark sky maps.
On the evening before my flight, I packed all my gear including my Orion ED80, Vixen Porta mount, finderscope, Telrad reflex site, and a selection of eyepieces. This was the first time I’d flown with a telescope, so I was a little worried about transporting my equipment but everything went off without a hitch, including airport security. I have a very sturdy Stellarvue carry-on hard case that fits the ED80, diagonal, Telrad, finderscope (underneath the Telrad in this picture), and eyepieces. The only eyepiece that doesn’t fit in the hard case is the big 40mm Williams Optics wide angle, which I carried in its box in my backpack. And the Vixen Porta, once disassembled, fit (rather snugly) into a suitcase borrowed from my friend jD.
In addition to the astro equipment and cold weather gear, I also had to pack for my conference, so I pared down to essential equipment only. In terms of atlases and books, I brought only the Pocket Sky Atlas and my Nexus 7 tablet (more on that in another entry).
On Thursday, I flew to Phoenix, took the shuttle to the rental car center, loaded my suitcase, telescope case, and backpack into the car, and started driving. With only a stop for groceries along the way, I made the beautiful 5 hour drive to Glenwood.
I arrived at my Airbnb guest house around 7 pm. The host turned out to be wonderful and the property beautiful (message me if you’re interested in details). I quickly got settled in and prepared for my first night’s observing. I’d arrived too late for my preferred practice of surveying the area for choice sites, so I just went up on the raised levee adjoining the property. Despite some scattered clouds and nearby mountains slightly impeding the horizon, the conditions were beyond anything I’ve experienced. I stayed out from the end of twilight around 9 pm to about 5 am. It was cold, in the mid-30’s, but the area was sheltered from wind, so it was quite comfortable. I wore the following:
- long underwear
- ski pants
- thick socks and boots
- long undershirt
- long sleeved shirt
- wool sweater
- fleece jacket
- gore-tex shell with hood
- neoprene facemask
- wool cap
- windproof liner gloves
- snowboarding mittens (when not handling equipment)
The list of objects I viewed that night/morning:
- NGC 3628
- NGC 4388
- NGC 4435
- NGC 4438
- NGC 4461
- NGC 4473
- NGC 4477
- NGC 4478
Around 3 AM, the Milky Way came up above the mountains to the east and were like nothing I’ve ever seen. I’ve camped under the black zone skies of northern Nevada, but with either moonlight or light pollution from other campers, RVs, etc. At first, I actually thought the Milky Way was intruding clouds, but then realized that they couldn’t be because there was no light pollution to illuminate clouds. Under black skies, clouds simply appear as the absence of stars, like blotches of nothingness in the tapestry of the night. This was the Milky Way, brighter and clearer than I’ve ever seen. With dark-adapted eyes, it was like something seen only in photographs. Sagittarius was astounding. I’m sorry that I just don’t have words to do justice to the beauty of it.
I packed my gear around 5 am and returned to my cabin. I ate a ham sandwich (famished), chugged some V8 (parched), washed up, and then collapsed into bed as the pre-dawn glow grew in the eastern sky.
More from the following nights to follow soon…
On August 14, amateur astronomer Koichi Itagaki discovered a nova in the constellation Delphinus. He did this with a 180 mm reflector telescope.
For comparison, my Zhumell Z8 is a 200 mm reflector. Amazing job, Mr. Itagaki! (His reflector is probably on an equatorial mount as his discovery was through photographic comparison).
We had a nice viewing of it on Saturday night, Aug. 17th. I was able to spot it very quickly with 12x70 binoculars and Sky and Telescope’s helpful star map:
1. Start at Delphinus
2. Scan north-northwest to locate a funny, lopsided trapezoid with two little “eyes” in the middle.
3. Move west a couple of degrees to the nova. For orientation, a magnitude 5.7 star lies just 1 or 2 degrees N-NE of the nova. Both that star and the nova have slightly dimmer close neighbors, though these may not be visible in binos. The 4 stars together form a long, narrow rectangle.
I used the ED80 (80mm f/7.5) at 20x (30 mm William Optics widefield eyepiece) for a more detailed comparison to the Uranometria 2000.0 star atlas and to share the views with others. Through the ED80, the nova appeared to me to be at least 5.5 in magnitude, by rough comparison to its 5.7 neighbor, which is in the ballpark of professional estimates.
So what is this nova thing? From the Sky and Telescope article:
A classical nova happens in a special kind of tightly-orbiting binary star system: one where a relatively normal star pours a stream of hydrogen onto the surface of a companion white dwarf. When the layer of fresh hydrogen on the white dwarf’s surface grows thick and dense enough, the bottom of the layer explodes in a runaway hydrogen-fusion reaction — a hydrogen bomb in the shape of a thin shell roughly the size of Earth. The underlying white dwarf remains intact, and as new hydrogen builds up, the process may repeat in a few years to tens of thousands of years.
Overall, it was a fun treat to witness such a relatively ephemeral cosmic event. Thank you, Mr. Itagaki!
EDIT—Here’s a neat diagram from the wikipedia entry on novae.
EDIT 2—I misread the chart I found. What I took for star designations were actually just the magnitudes. I’ve corrected the above entries.
EDIT 3—This article at Universe Today has the clearest diagrams I’ve found that show the exact location of the nova.
The skies were clear tonight and the weather was slightly less ridiculously cold than it has been recently. I did some quick observing of a few standard winter treats including M42 Orion Nebula, M45 Pleiades, and Jupiter which is just past opposition and a very nice sight even in my small ED80 telescope. Both equatorial belts were easily visible. I thought I saw the Great Red Spot, but I just checked my Stellarium software, which tells me that the GRS didn’t come into view until after I came inside. Ah well, wishful thinking.
Jupiter is in conjunction with HIP 20417, a lovely red star in Taurus. Tonight, it looked like an eccentric fifth Galilean moon, hanging just southeast of Io. I snapped a few pics of the evenings events.
Jupiter and the Galilean moons with a guest
Apologies for the long absence. Let’s restart our exploration of the serried multitude of the stars with a review of some lighter (and simultaneously darker) quasi-scientific entertainment.
The Manhattan Projects is an alternate-history retelling of the Manhattan Project, the secret US government program that created the atomic bomb. The main characters include the Manhattan Project director Leslie Grove, Robert Oppenheimer, Albert Einstein, Robert Feynman, Enrico Fermi, Harry Daghlian, Werner von Braun, and Franklin Delano Roosevelt
The first twist in this alternate universe is that the atomic bomb is the merest trifle in the Manhattan Project’s super-scientific advances, which include dimensional portals and contact with extraterrestrials.
The second twist is that the alternate versions of these famous geniuses are all deranged in some manner, ranging from garden-variety narcissists and alcoholics to multiple-personality-disordered psychopaths.
The storyline is dark, cynical, and violent. This will not be to everyone’s taste, but if you can stomach this sort of thing, it’s also incredibly imaginative, thrilling, and darkly hilarious. Who doesn’t want to see famous scientists machine-gun down Japanese robots?
Pitarra’s art is beautiful—detailed and energetic, leaning in the direction of Geof Darrow and Moebius (two of my favorites), while still maintaining absolute clarity of action.
I’ve finished Volume 1, which collects issues #1-5. Issue #11 is already out, so I must decide whether to wait for Volume 2 or to catch up on the individual issues. Regardless, I am hooked.
The tagline on the back cover of Volume 1 reads: “Science. Bad.”
And when it’s bad, it’s oh so good!
Last night, our friends Jim and Izzy joined my wife and I for an outing at an undisclosed location north of San Francisco. I’d noted three potential yellow-zone locations to check out—2 categories darker than the red zones where we all live. The roads to two were blocked. The third turned out to be an excellent site.
About light-pollution zones:
- The World Atlas of the Artificial Night Sky Brightness has been the de facto standard reference for light pollution since it was published in 2001. It was modeled from 1996-1997 satellite data.
- In 2010, amateur astronomer DaveL recalculated the map using data from 2001. In my opinion, DaveL’s map with Google Maps overlay is the best resource for amateur astronomers.
- DaveL’s page has the new and old maps with supporting information.
Our yellow zone site was indeed noticeabley darker than Berkeley. On Friday night, I could see only Alpha, Mu, and Beta Serpentis in Serpens Caput, but last night, I could easily make out the brightest 7 or so stars in the constellation. In addition, we had a 360° unobstructed view, with noticeable skyglow only to the south.
Jim brought his 4.5” reflector on an EQ (equatorial) mount. I brought my 8” Dobsonian reflector.
A note about equatorial mounts: I know nothing about them other than what I have read. Their big advantage is that one of the rotational axes of the mount can be aligned with the the Earth’s polar axis (or the star Polaris, which is close enough). This allows easier tracking of objects as the Earth rotates (or the sky rotates if referring to a fixed reference point on the Earth’s surface). The disadvantage is more difficult set up and operation compared to a simple mount like a Dobsonian, though this difficulty is reduced or erased with experience.
We were set up around 9:45 and got in over 90 minutes of observing. Because of the unobstructed view to the west, I decided to tag some of the Messier objects in the Virgo galaxy cluster, pretty much the final chance to see them this year.
- M49—Fairly easily located by starhopping west and south from Epsilon Virginis aka Vindemiatrix. M49 is just west and north of a convenient nearby landmark—a line of three stars, the western pair closer together.
- NGC 4526—a bonus item that I was not looking for. This galaxy lies right in between the two closer stars of those three in a line.
- M61—And then hopping further south and west from there. This galaxy makes a lopsided rectangle with three nearby stars, one of which is a variable (which makes it standout on star maps, even if not to the eye).
- M60—Back up to Vinemiatrix, then northwest to find another line of three stars: 41 Virginis, a fainter star (actually a multiple), then 34 Virginis (also a multiple). This line points right at M60, about 1° from 34 Vir.
- M59—Just west of M60 and a hair north.
- M58—Moving west there are six stars that form a sort of squashed wedge, like a banana, pointing northeast. M58 lies just east of the northern tip.
- M89 and M90 are a hop to the north. These two were just barely visible to me, much more faint than M58. This makes sense since M89 is a hair dimmer in magnitude than M58 and M90 is similar in magnitude to M58 but larger and thus more diffuse.
All in all, a great night of observing with great friends at a nice location. I am tempted to name this viewing site Lot 49, in honor of one of my favorite authors and the secret nature of its location.
Summer is the season for backyard astronomy… except when there’s fog, which is most of the time in the San Francisco Bay Area! Tonight was a nice clear night, with the moon both a thin crescent and setting shortly after sunset.
Summer is also the season for Hercules and its neighbors. Tonight was a globular mini-marathon.
- M5—The only Messier object in Serpens Cauda (Serpent’s tail) and a lovely one.
- M10 and M12—Neighboring clusters in Ophiucus. M12 is slightly lower magnitude (less bright) than these other clusters, and a bit harder to locate in light-polluted skies due to slightly sparser nearby stars.
- M13—The Great Globular Cluster in Hercules. I’ll never tire of this amazing sight.
- M92—The other big cluster in Hercules, and sometimes overlooked, but still amazing.