I am actually rather surprised it had not happened to me before. Given the number of times I have dodged animals along Saddle Road. Pigs, sheep, mongoose, feral cats, francolins, quail… I had hit a turkey a few years back, but this was my first encounter with a larger animal.
I really prefer to avoid killing, but luck was not with me or the poor mouflon sheep this time.
It came into the headlights from the side at a full run, I had no real chance of avoiding the collision. Fortunately it did not hit square on, as it was a fairly big ram. It struck a glancing blow under the passenger side headlight, with a dull thud I can still remember vividly.
Damage on the front quarter of a Ford Explorer due to a Mouflon SheepThe results were pretty ugly, bits of sheep across the road, blood and guts sprayed down the side of the vehicle. What was left of the unfortunate ram was left wrapped around a fencepost, thrown well clear of the collision. Yes, I have a photo. No, I am not posting it here. It is rather gory.
I did have one bit of luck, there was no critical damage, allowing me to continue on to headquarters in the middle of the night. I was a bit concerned when I found fluid leaking from under the vehicle, but it didn’t look yellow enough to be antifreeze. Further inspection showed it to be wiper fluid, the reservoir is just above the wheel and had taken a hit. In my flashlight beam it was slowly draining onto the road.
I inspected the tire, the brake line and everything else in the impact zone before continuing my journey. As I pulled out there was a chime and a message in the dash… “Wiper Fluid Low”… as if I was worried about wiper fluid!
Mike, our company mechanic, places the damage at about $4k in a quick guess. I suspect he is about right. Given the size of the ram and the speed I am really surprised it was not worse. I did do Mike a favor, I hosed the vehicle down before leaving it parked it in front of our little shop. With the contents of the sheep all down the side, it was pretty rank!
I always feel bad about killing a wild animal like this. My only solace is that feral mouflon are a species that represent a problem, with a population that is growing to the point it is damaging the mountain. I recall a few years ago when sighting sheep was a rare occurrence along Saddle Road, for the last year it has been difficult not to see them, with large herds a common sight.
I am not the first to hit a sheep in an observatory vehicle lately. This will not save me from the inevitable ribbing I will receive. There will be jokes, and I will just have to laugh along.
I am waiting for the Moon to leave the evening sky before shooting the comet again. In the meantime I am processing more of the material obtained earlier in the month. In this case a photo of Comet 103P/Hartley 2 taken October 6th with Keck 2 and DEIMOS. The image marks the first time I have attempted to take and process an image with a 10m telescope. Just a wee bit larger than the 76mm refractor I usually use to take astrophotos!
The image is notable for its complete lack of any interesting structure. There are no jets, shells or other inner coma detail visible. The tail is simply a general brightening to the southwest (lower right in this image).
The comet is moving very quickly across the sky, even more so with the high magnification lent by a large telescope. Even short exposures turn the stars into long streaks. In this case multicolor streaks as the camera cycles through the filters needed for a color image.
Comet 103P Hartley 2 with Keck2 and DEIMOS 6Oct2010 @ 7:27UT, 3x60s, 3x60s and 3x120s with standard BVR astrometric filters, credit: Cooper/Wirth/W.M. Keck Observatory
Visual astronomy is the practice of pushing our built in optical detectors to the limits of performance. Our eyes are surprisingly good optical instruments, and until the advent of film about a century ago were the only means we had of observing the universe. Even now, in the age of sensitive electronic detectors there are those who appreciate the view of the heavens through our own eyes.
The edge on spiral M104 photographed with a Collins I3 Image IntensifierThis does not keep some from trying other ways to improve the view. Night vision technology, devices pioneered by the military that amplify the available light, offer intriguing possibilities. Available in compact packages these amplifier image tubes have been incorporated into an eyepiece sized package that can replace a standard eyepiece and offer an amplified image.
The image tube operates by charging a grid to a high voltage inside a small vacuum tube. Incoming light (photons) strike this grid and create a shower of electrons that continue onwards to strike a phosphor screen at the rear of the tube. A single photon can create a shower of hundreds of electrons, a very large signal gain. The phosphor screen glows where struck by photons, creating a image of the amplified signal.
A bright image is seen on the screen of the object, hundreds of times brighter than the original. The image is green, as result of the phosphor, this amplification is a monochromatic process. There is some noise in the image, random “sparkles” called scintillation that result when electrons leave the charged grid in a random fashion.
The images shown here are taken with the Collins I3 eyepiece or I3piece. The device is a very nicely built unit that is about the same size as a modern high quality eyepiece. Actually it is much smaller than some of the large designer eyepieces seen on some telescopes. An internal battery means there are no cables resulting in a neat package. The intensifier has a standard 1.25″ or 2″ nose piece threaded to accept standard astronomy filters.
The image intensifier is not a panacea, there are some objects where the intensifier works well, and others where it does not perform. Globular clusters and planetary nebulae are quite dramatically represented in the intensified view. It is faint, low surface brightness objects like galaxies and extended nebulae that are often better appreciated with a normal eyepiece. Switching back and forth is generally a poor idea as using the intensifier decreases dark adaptation.
The edge on spiral M51 photographed with a Collins I3 Image IntensifierDuring personal observations of galaxy views in two large telescopes side by side, I noted more detail in the un-amplified images compared to those using the intensifier, particularly where subtle detail was concerned. I have had opportunity to observe the same galaxy in my 18″ f/4.5 followed by the view in a 24″ with the intensifier. The images in the intensifier were much brighter, but the contrast range seem compressed, such that HII regions and similar low contrast details disappeared.
One place where the value of the intensifier is undeniable is in public outreach. The live views of bright galaxies show far more detail to the inexperienced observer that they would otherwise have missed in the eyepiece view. A spiral galaxy is clearly a spiral galaxy, even to a first time observer. In addition the intensifier can be used to provide views of faint objects under less that ideal conditions. Addition of a narrowband filter can increase the signal to noise and allow viewing of emission nebulae even with substantial light pollution from natural (e.g. the Moon) or artificial sources.
Unfortunately the Collins intensified eyepieces are no longer available from the manufacturer, though the website still appears functional. There is an equivalent product from BIPH which uses the same technology. At nearly four thousand dollars these devices are not for everyone. they can be used to good effect under the right conditions.
As the big front-end loader approached my borrowed trailer with a full scoop I expected the operator to carefully dump just enough for a load. No… he dumped it all. The trailer disappeared in a cloud of dust and an avalanche of shredded mulch. As the cloud cleared, I saw that the trailer was nearly entirely buried. The loader operator cheerfully called out to me, and with a smile he asked if I wanted another scoop.
Having a trailer loaded with mulch at the Kealakehe transfer station“Umm… Uh… I don’t think I need any more. Thanks!?!” A little shocked, I gazed at the pile of mulch hitched to my vehicle and wondered how I was going to get it out, profoundly glad I had remembered to bring a shovel.
A telescope relies on the quality of the primary mirror. The shape must be exquisite perfection, with errors measured in millionths of a meter. The reflective coating must also perform to high standards, reflecting well over 90% of the light across a wide region of the spectrum.
A Keck mirror segment after stripping and cleaning, ready to place in the chamber to receive a new reflective coatingKeck observatory carefully monitors each primary mirror to insure it is performing accurately. Instruments can detect small variations in the shape, indicating where there may be trouble in the support structure and active positioning of the segments. The coating is tested for reflectivity, to insure as much precious starlight goes to the instrument as possible.
Keck uses pure aluminum to coat the surface of each mirror segment, chosen for its excellent reflectivity in the visible and infrared parts of the spectrum. It takes only 20.5 grams of aluminum to coat an entire Keck primary mirror. This thin layer of aluminum degrades with time, losing several percent of it’s reflectivity each year. Eventually it must be replaced.
Re-coating a mirror is a painstaking process of stripping the old coating, carefully cleaning the mirror, the placing the mirror in a vacuum chamber to deposit a new metal coating onto the glass. The process takes about a week per segment, with one full time technician dedicated to the task, with a little help to handle some of the more intense parts of the process.
An advantage of a segmented telescope is that individual segments may be swapped in a single day. Telescopes utilizing monolithic mirrors must shut down for weeks to remove the primary mirror, strip clean and re-coat. With spare segments available the maintenance crew can perform the task of re-coating on a reasonable schedule, without taking the telescope off sky for an extended period.
At Keck there is a special storage facility for segments awaiting re-coating and those that are ready for installation back into the telescope. The process is continuous, once the last segment is finished, it is time to start the rotation again.
Glow discharge cleaning the mirror surface prior to aluminizingThe first step in replacing the old coating is to chemically strip the old coating. This is done in a special bay used only for this purpose. An acid solution dissolves the aluminum revealing the glass below. The mirror is the extensively cleaned to remove any remaining contamination. If the mirror surface is not perfectly clean, the new aluminum coating will not adhere properly. All of the chemicals used are caught in a closed system for proper disposal off the mountain.
Once cleaned the mirror is moves to a large vacuum chamber where the new coating will be deposited. Here the mirror is positioned face downwards. With the cover reinstalled on the chamber it will take most of a day to pump out the air and ready the chamber for coating.
Glow discharge is a method of cleaning a surface prior to vacuum coating it. A high electrical charge is placed on an electrode just below the mirror in a partial vacuum. The result is something like creating a storm of electrons to blow any remaining impurities off the surface of the mirror. It is also a very beautiful process, looking through the ports one can see a brilliant violet haze around the electrode with sparks flickering along it’s length.
The bright glow of coils of aluminum vaporizing in the coating chamberThe final step is to vaporize the aluminum itself. In the bottom of the coating chamber are arranged a number of electrodes, each made of pure aluminum. By electrically heating these electrodes a few ounces of metal is vaporized. In the vacuum this aluminum forms a cloud of metal that coats everything in the chamber, including the mirror segment positioned above the electrodes. An instrument measures the buildup of the layer and shuts off the current when the deposited layer reaches the desired thickness of 100nm.
The coating process takes only a few minutes once the electrodes are turned on. Peering in through the small view port a cheery red glow is seen from each of the electrodes at the bottom of the chamber. The view only lasts a few moments as the cloud of vaporized aluminum soon reaches the view port and the glow fades as the window is covered by a layer of deposited aluminum along with the mirror segment.
What emerges from the chamber is a mirror with a beautiful, reflective metal coating. A few tests will be performed to insure the coating meets specification. If all is well the mirror segment will be prepared for installation in the telescope. It will await another segment exchange when it will replace another segment that has become dull with years of exposure to the elements. That segment will then receive it’s turn in the coating chamber.
It is an observation I have made before, but one that continually amazes me… Each Keck telescope consists of three hundred tons of steel and glass, with one simple purpose, to hold a few grams of aluminum in the perfect shape necessary to collect the light from distant stars and galaxies.
Looking into the optics of the Keck 2 telescopeEach segment of the primary mirror is covered with a very thin coating of pure aluminum, about 100nm thick, this is 1/10,000 of a millimeter or 0.000004 inches. Aluminum is used in the Keck telescope as it reflects over 92% of the light across a wide wavelength range extending from the UV well into the infrared.
The layer is just thick enough to reflect nearly all of the light, any thinner and too much light would penetrate the mirror, any thicker and small variations in the coating would begin to distort the shape of the mirror.
How much aluminum?
Density of Al…
2.70g/cm³
Area of a Keck Primary…
36 x 2.598 x (0.9m)² = 75.75m²
Mass of Al…
2.70g/cm³ x 75.75m² x 100nm x 1,000,000cm³/m³ = 20.45g
20.45g = 0.71oz (if you prefer imperial)
Just how much aluminum is really on each Keck primary mirror? Simple enough to calculate… just multiply the surface area of thirty six hexagons by the thickness of the aluminum layer to figure the total mass of metal used.
The figures are found in the sidebar, and the answer is surprisingly little, about 20.5g. In comparison, an empty 12oz soda can weighs about 15g, thus it take a bit more than one soda can of aluminum to cover the Keck’s 10 meter primary mirror.
There is much more to a telescope than just one simple layer of aluminum. But that one component is critical. It is the mirror that gets a great deal of the attention. The primary mirror is what gives a large observatory the ability to capture light from the earliest eras of the universe, billions of years in the past.
A crescent Mercury, 16Apr2010Earlier this month, as Mercury was slipping back into the glare of the Sun, I had an opportunity to shoot some webcam material of the planet in hopes of getting an image of the crescent shape. The resulting image does not look like much, but I have to think it really isn’t all that bad.
The photo does represent Mercury fairly well, at least the normal view you get in a telescope. As the innermost planet does not get very far from the Sun, it is typically seen quite low on the horizon. This leads to poor views seen through a great deal of atmospheric distortion.
What the photo does not show is the chromatic distortion, this was corrected during processing of the photo. The atmosphere will also break up the color, refracting the light when an object is low on the horizon. The processing software allows realigning the color planes, correcting much of the effect.
It has been a week since the paving machine began it’s slow work. Gone is the patchwork of pavement, a road seemingly built by many years of repair crews, so many patches that little remained of whatever pavement originally existed. Bit by bit the ragged road we have bounced over for many years is being covered by a smooth surface.
Crews laying asphalt on Saddle Road near MP40 in 2009The machine has reached milepost 48, a half mile more than that in the Kona bound lane. The first layer mostly completed by the county crews. From there to the district line the lanes are pleasant and smooth drive, such a contrast from the old pavement. This latest segment leads to the section that was paved last year, from MP48 to the rebuilt sections across PTA, the road is nothing like the rough experience of Saddle Road past. The only rough section remaining is the few miles from MP48 to the western terminus at Mamalahoa highway.
While making a pass in each lane, the crews left about a foot in the middle unpaved for now, keeping the center line exposed, and creating a road a few inches wider. Breaking with tradition, no one drives the center of the road in the repaved section, avoiding the small trough created between the lanes.
The infamous Saddle Road of fable and legend is vanishing, repaved or completely rebuilt. Those of us who drive it regularly enjoy the new smooth ride, but in some ways we also mourn the disappearance of the real Saddle Road.
The Telrad finder is one of the most useful telescope accessories ever invented. A set of glowing red rings showing you, at a glance, exactly where your telescope is pointed in the sky. I have one on each of my telescopes. The Mauna Kea VIS also equips each telescope with one of these simple devices.
They do not work so well after hitting the ground a few times.
As I have mentioned in the past, the equipment at the Mauna Kea VIS gets used hard. It is setup every single night of the year. Thousands upon thousands of people use these telescopes to see the wonders of the night sky, the first time for many. The wear and accidental damage in the darkness takes a toll.
A box full of broken Telrad finders awaiting repairWhen Deb and I were last at the VIS we spent the day cleaning eyepieces and making other repairs to the ‘scopes. One of the things I found in the storeroom was a small pile of broken Telrads. Some were missing windows, many had broken battery holders, mirrors were missing and reticle holders hanging loose. Many had been patched back together with tape or hot glue, attempts to keep them working for another night.
Quite a few had reticles that were missing or melted by exposure to sunlight. The lens that focuses the reticle’s ring pattern, projecting it into the sky, will also focus sunlight on the reticle, quickly melting the thin film if a Telrad is left in the sun.
Gathering up partial and scattered parts I collected a box of finders that I can work on later. It made quite a pathetic sight, a box of broken Telrads. A couple evenings later, five of the Telrads are now rebuilt and ready to return to duty. Four more are awaiting replacement reticles before I can call them completed. I will take them back up next time we are on the mountain, but I expect we will find something else that needs to be fixed.
