As I mentioned in our last post, we had the opportunity to meet up with college buddies Anthony and Anita (University of Iowa, 1970s) in Flagstaff Sunday. Anthony and I met in a general astronomy class (taught by the famous James Van Allen), so a natural place to meet up was Lowell Observatory. Melinda had never seen it, so it was a date!
Lowell Observatory is a private observatory, started by Percival Lowell with the construction of a 24" refractor on a hilltop in Flagstaff in 1894. It was at Lowell that Clyde Tombaugh discovered Pluto in 1930, working on a search for "Planet X" initiated by Percival himself. Though Pluto has been downsized to a dwarf planet, Lowell is at the forefront of astronomical research, and a partner in the new Discovery Channel Telescope, a 4.3 meter diameter telescope mentioned a few posts ago, since the mirror is under construction across the street at the Optical Sciences Center. We took the afternoon tour after meeting up with our friends, and brand new Lowell employee Jonathan, whom I've known for a decade and a half from the Grand Canyon Star Party. Jonathan just moved to town 2 weeks before, so it was great seeing him. His blog "Every Day is a New Adventure" is linked down on the right side of this page.
Shown here, our tour guide Mary Jane is showing off the relative sizes of the telescope diameters at Lowell. The original 24" is shown in brown, the scope that had been their largest for some time is a 72" (shown in yellow), and the new 4.3 meter Discovery Channel Telescope, shown in blue. Since the relative power of a telescope is in it's light gathering power, the DCT will be powerful indeed!
The tour starts with a walking tour of the 24", now nearly 115 years old. While no longer routinely used for research, it is still an impressive instrument. In fact, the night before, Anthony and Anita had gone to the public observing session and were privileged to observe Saturn through it. It is an interesting telescope - a combination of state-of-the-art of the Victorian age, combined with the craftsmanship of the Sykes Brothers, local craftsmen whom Percival Lowell put to work supporting all aspects of the Observatory. The lens cover for the big guide scope - a frying pan from the kitchen of Constance Lowell that happened to be the right diameter...
The thing I really like about Lowell is that it has a real sense of history. Kitt Peak National Observatory near Tucson, while only half the age of Lowell, has very little in historical displays. Lowell revels in displays of early instruments, telescopes and artwork. The Slipher Rotunda Museum, shown here, has all the above as well as duplicates of the Pluto discovery plates mounted on the blink comparator that Clyde Tombaugh himself used to discover the planet. Here Melinda sits at the comparator examining Pluto images.
A short walk from the museum is a scale model of the solar system, 1 million miles to the inch, culminating in Pluto located at the base of the telescope where it was discovered. Such scale models are interesting demonstrations that space is truly a pretty empty place, with the nearest stars scaled distance out near Los Angeles, CA. Just a short walk up the hill (near the scaled distance of Jupiter, we found a recently installed memorial to Robert Burnham Jr., a Lowell Staffer in the 60s and 70s and author of the classic "Burnham's Celestial handbook". Our friend Jennifer Polakis was instrumental in getting the memorial built and installed this last year, and it was my first time seeing it. Well done Jen!
And after a busy day of driving and touring the local Observatories, what are we to do? Why go off and find some local micro brew beer! We located the Flagstaff Brewing Company in the bustling downtown area, and enjoyed some ales while getting caught up and reacquainted. The next morning Melinda and I headed east towards Meteor Crater, while Anthony and Anita went south to visit Arcosanti. Now gainfully employed Jonathan headed up the hill to his new job at Lowell, after enjoying the Sunday tour with us. But the day was a great time and we made plans to cross paths again - we'll likely see Jonathan at the Grand Canyon Star party in June, and I may get to swing by Anthony and Anita's house during RAGBRAI week in July. Looking forward to it!
Tuesday, April 27, 2010
Monday, April 26, 2010
Unknown Arizona!
Arizona is a big state. Though we get out of the house pretty frequently, we tend to go to the same places (Grand Canyon, Kitt Peak, Chiricahuas), and generally always take the interstate to save time and mileage. There are huge swaths of the state we've never seen, let alone explored.
But we've expanded our horizons a bit - we took a quick 2-day road trip to meet friends in Flagstaff Sunday afternoon (a future post), returning today (Monday). Melinda had never seen Meteor Crater, and it has been nearly 15 years for me, so we took the side trip there on the way home. While it would have been shorter and much faster to return to Flag and back on the Interstate system, we decided to take an alternate route and explore a bit of the state neither of us have seen. As shown on the map, our trip up is in green (about 260 miles, 4 hours), the return trip in blue (335 miles, 6.5 hours)
Hitting the I-40 after the Crater, we headed east for Winslow, yes, the destination of the Eagles' hit song "Take it Easy" from the '70s, which has been fully taken advantage of by the local Chamber of Commerce, where it is mysteriously piped out of hidden speakers on the sidewalks of town. We didn't hang out, or even examine the sculpture of the singer and the mural of the woman in the flatbed Ford of the song. We hotfooted it south into the wilderness of pines and mountains.
It was a beautiful trip, and while we went the speed limit, the lack of busy Interstate traffic somehow seemed to make the trip more leisurely. There were still snowbanks among the pines, burbling brooks, and a multitude of tiny to midsized towns I'd mostly heard of, but have never seen. Today's list included Strawberry, Pine, Payson, Rye, Punkin Center, Globe, Christmas, Winkelman, Dudleyville, Mammoth and finally Oracle before hitting the Tucson suburbs...
One of the really incongruous sights was the view of Roosevelt Lake in the middle of the desert, with Egrets and Herons nesting in the lakeside trees! There is a whole series of lakes that not only act as a water source for the metropolitan Phoenix area, but also generate hydroelectric power for the State. It just seems a shocking blue against the earthtones of the arid desert.
The springtime desert was spectacular too. With all the life zones we passed in dropping from the Ponderosa pines at 7,000 feet Flagstaff, to the 2,000 feet of the San Pedro Valley, we saw hillsides covered in the pink flowers of the early-blooming hedgehog cacti, to hillsides covered in the bright yellow Brittlebush among the Saguaros. As we approached Globe, 100 miles north of Tucson, we encountered the mining district, and even then the geology distinctly changed with the strong tilted rock layering shown in the picture here, to mineral veins exposed in the road cuts, and the truckloads of copper plates from the mines headed north.
It was a fun drive, demonstrating that allowing a little extra time and miles can reveal more about where we live here. We certainly saw places we'd like to return and spend more time, so today's first explorations were well spent!
But we've expanded our horizons a bit - we took a quick 2-day road trip to meet friends in Flagstaff Sunday afternoon (a future post), returning today (Monday). Melinda had never seen Meteor Crater, and it has been nearly 15 years for me, so we took the side trip there on the way home. While it would have been shorter and much faster to return to Flag and back on the Interstate system, we decided to take an alternate route and explore a bit of the state neither of us have seen. As shown on the map, our trip up is in green (about 260 miles, 4 hours), the return trip in blue (335 miles, 6.5 hours)
Hitting the I-40 after the Crater, we headed east for Winslow, yes, the destination of the Eagles' hit song "Take it Easy" from the '70s, which has been fully taken advantage of by the local Chamber of Commerce, where it is mysteriously piped out of hidden speakers on the sidewalks of town. We didn't hang out, or even examine the sculpture of the singer and the mural of the woman in the flatbed Ford of the song. We hotfooted it south into the wilderness of pines and mountains.
It was a beautiful trip, and while we went the speed limit, the lack of busy Interstate traffic somehow seemed to make the trip more leisurely. There were still snowbanks among the pines, burbling brooks, and a multitude of tiny to midsized towns I'd mostly heard of, but have never seen. Today's list included Strawberry, Pine, Payson, Rye, Punkin Center, Globe, Christmas, Winkelman, Dudleyville, Mammoth and finally Oracle before hitting the Tucson suburbs...
One of the really incongruous sights was the view of Roosevelt Lake in the middle of the desert, with Egrets and Herons nesting in the lakeside trees! There is a whole series of lakes that not only act as a water source for the metropolitan Phoenix area, but also generate hydroelectric power for the State. It just seems a shocking blue against the earthtones of the arid desert.
The springtime desert was spectacular too. With all the life zones we passed in dropping from the Ponderosa pines at 7,000 feet Flagstaff, to the 2,000 feet of the San Pedro Valley, we saw hillsides covered in the pink flowers of the early-blooming hedgehog cacti, to hillsides covered in the bright yellow Brittlebush among the Saguaros. As we approached Globe, 100 miles north of Tucson, we encountered the mining district, and even then the geology distinctly changed with the strong tilted rock layering shown in the picture here, to mineral veins exposed in the road cuts, and the truckloads of copper plates from the mines headed north.
It was a fun drive, demonstrating that allowing a little extra time and miles can reveal more about where we live here. We certainly saw places we'd like to return and spend more time, so today's first explorations were well spent!
Labels:
Roadtrip Stories
Saturday, April 24, 2010
More 3-D pics
These are the last of our pictures from our Rocky Point, Mexico trip last weekend. Our walk along the beach at low tide found us collecting a multitude of shell designs. We had to be sure the ones we picked up were unoccupied as many of them, especially the ones perched atop rocks were inhabited by hermit crabs! They were pretty shy, but they eventually revealed themselves for a picture.
We did find a pretty wide variety that were unoccupied, only a few of which are shown in this handful. Again, refer back a post or two about hints to view the stereo pairs. You need to cross your eyes to see the 3-D effect. Some people have good luck with the thumbnails, but if you don't get too close to the computer screen, you should be able to click on them for the full-size images. I'm trying to stay away from horizontal format images, which would require crossing your eyes more. It seems easier on the vertical format pairs...
The rest of these pairs were taken on the return trip to Tucson at a "pit stop" at organ Pipe National Monument. There is a nature trail we followed for a couple hundred yards. Many cacti were in bloom or soon to be, so 3-D opportunities abounded. First up is this Hedgehog Cactus. Normally an early Spring bloomer, you an see this is the last blossom in full flower.
I love the form of the Cholla Cactus skeleton, which gives the living plant it's strength. It was a natural to try to record it. Included are both the nearly full horizontal frame and a crop of a vertical format version to make it easier to merge the images. Be sure to give feedback which you prefer, but I suspect the closeup crop is better.
Prickly Pear is busting out in bloom all over, though these weren't quite out yet last weekend. Still a great stereo subject. Again, a nearly full frame and a closeup crop. I think the blowup is my new favorite - I like the little explosions of little spines visible in the close shot.
Here is the namesake of the Monument, or at least the top business end of an Organ Cactus. What caught my eye was that the top of the cactus had many blossoms of the background Ocotillo impaled on the spines. This pair is a closeup and an even-bigger-closeup of the red Ocotillo blossoms.
Another quick road trip tomorrow and Monday - a report from the road if we have Internet access...
We did find a pretty wide variety that were unoccupied, only a few of which are shown in this handful. Again, refer back a post or two about hints to view the stereo pairs. You need to cross your eyes to see the 3-D effect. Some people have good luck with the thumbnails, but if you don't get too close to the computer screen, you should be able to click on them for the full-size images. I'm trying to stay away from horizontal format images, which would require crossing your eyes more. It seems easier on the vertical format pairs...
The rest of these pairs were taken on the return trip to Tucson at a "pit stop" at organ Pipe National Monument. There is a nature trail we followed for a couple hundred yards. Many cacti were in bloom or soon to be, so 3-D opportunities abounded. First up is this Hedgehog Cactus. Normally an early Spring bloomer, you an see this is the last blossom in full flower.
I love the form of the Cholla Cactus skeleton, which gives the living plant it's strength. It was a natural to try to record it. Included are both the nearly full horizontal frame and a crop of a vertical format version to make it easier to merge the images. Be sure to give feedback which you prefer, but I suspect the closeup crop is better.
Prickly Pear is busting out in bloom all over, though these weren't quite out yet last weekend. Still a great stereo subject. Again, a nearly full frame and a closeup crop. I think the blowup is my new favorite - I like the little explosions of little spines visible in the close shot.
Here is the namesake of the Monument, or at least the top business end of an Organ Cactus. What caught my eye was that the top of the cactus had many blossoms of the background Ocotillo impaled on the spines. This pair is a closeup and an even-bigger-closeup of the red Ocotillo blossoms.
Another quick road trip tomorrow and Monday - a report from the road if we have Internet access...
Labels:
3-D Images,
Roadtrip Stories
Tuesday, April 20, 2010
Rocky Point Redux
After a spectacular 3 day Easter Weekend in Rocky Point visiting our friend Margie and meeting new friends Rick and Linda (who were also visiting that weekend), we looked at Melinda's work schedule and decided to go again this last weekend! Margie, always the gracious host, didn't turn us away at inviting ourselves down again, so we made the trip, this time bringing our buddy Donna along. Donna is a Florida native exiled to the desert, so jumped at the chance to spend some beach time so close to Arizona. We headed down Saturday morning, arriving mid-afternoon in the sleepy tourist town, sleepy, at least compared to Easter Weekend! I joined Donna on a walk on the beach (that is her foot in the picture at left), while Melinda, who worked graveyard the night before, got a 40-wink nap.
Two weeks earlier, our group had headed to the old section of town to have dinner on the bluff overlooking the old port of Puerto Penasco. There are a couple restaurants up a few hundred feet overlooking not only a wide expanse of the Sea of Cortez, but also a bird's eye view of town and a long stretch of resort development. Over Easter, there was so much traffic with the end of spring break and Easter revelers that the police had closed off the streets and we couldn't get there. This time there weren't any crowd issues, so we made it up the hill. A couple years back, Margie, Melinda, me and a few others had eaten at "Captains" up at the very peak. Margie has heard the food is a little uneven, so this time we ate at the adjacent "Lighthouse". The food turned out as spectacular as the views. Donna and I both had steak and shrimp - the bacon-wrapped and grilled shrimp being quite Divine. Shown here in the growing twilight the brilliant Venus shines over the lights of town.
One of our interests this trip was the status of our friendly Osprey couple that we imaged in our last post. They were religious about staying on their eggs, so we were wondering if they had any babies yet. We have good news - there are at least 2 babies that we saw! The nest is deep enough that we saw them only rarely, but there are definitely at least 2 chicks. On Monday morning, a dreary day when it actually was spitting rain, I was photographing the nest after one had gone out for food. Luckily, after being gone a good 15 minutes, it returned with a sizable flounder to share. Note the little head popping up from the nest - a lil' baby Osprey! By noon, the weather had cleared, and I walked down to pace off the distance to the nest from Margie's house (a good 200 meters!). They don't really like visitors as they watched me like, well, hawks! Check out those talons - between those and the "barking" warning they gave, I didn't tarry!
The one thing that surprised veteran beachcomber Donna was the tidal amplitude. It was nearly full moon, just a couple days past new, and the low-to-high tide was over 5 meters (over 16 feet). While not sounding like a lot, with the shallow slope of the beach, at low tide, the Sea went out a couple hundred yards! Shown here are pictures from Saturday afternoon's nearly-high-tide compared to Sunday morning's low tide. Taken from nearly the same spot you can see the amazing difference. As I understand it, the tidal effect is amplified by the long, narrow, relatively shallow Sea of Cortez, and almost acts like water sloshing up the shallow end of a wading pool.
And of course, with my recent display of 3-D images in our last post, many of the pictures I took were of the stereoscopic kind, where 2 pictures are taken from slightly different angles. Refer back to that post for hints on fusing the pair together - some can see depth in the thumbnails, but click on the image to enlarge it to see the detail. I'll have more soon, but this one will do for now - it shows the shells of little crabs poised on low rocks waiting for the tide to come back in. It is Melinda's current favorite, so check it out!
Two weeks earlier, our group had headed to the old section of town to have dinner on the bluff overlooking the old port of Puerto Penasco. There are a couple restaurants up a few hundred feet overlooking not only a wide expanse of the Sea of Cortez, but also a bird's eye view of town and a long stretch of resort development. Over Easter, there was so much traffic with the end of spring break and Easter revelers that the police had closed off the streets and we couldn't get there. This time there weren't any crowd issues, so we made it up the hill. A couple years back, Margie, Melinda, me and a few others had eaten at "Captains" up at the very peak. Margie has heard the food is a little uneven, so this time we ate at the adjacent "Lighthouse". The food turned out as spectacular as the views. Donna and I both had steak and shrimp - the bacon-wrapped and grilled shrimp being quite Divine. Shown here in the growing twilight the brilliant Venus shines over the lights of town.
One of our interests this trip was the status of our friendly Osprey couple that we imaged in our last post. They were religious about staying on their eggs, so we were wondering if they had any babies yet. We have good news - there are at least 2 babies that we saw! The nest is deep enough that we saw them only rarely, but there are definitely at least 2 chicks. On Monday morning, a dreary day when it actually was spitting rain, I was photographing the nest after one had gone out for food. Luckily, after being gone a good 15 minutes, it returned with a sizable flounder to share. Note the little head popping up from the nest - a lil' baby Osprey! By noon, the weather had cleared, and I walked down to pace off the distance to the nest from Margie's house (a good 200 meters!). They don't really like visitors as they watched me like, well, hawks! Check out those talons - between those and the "barking" warning they gave, I didn't tarry!
The one thing that surprised veteran beachcomber Donna was the tidal amplitude. It was nearly full moon, just a couple days past new, and the low-to-high tide was over 5 meters (over 16 feet). While not sounding like a lot, with the shallow slope of the beach, at low tide, the Sea went out a couple hundred yards! Shown here are pictures from Saturday afternoon's nearly-high-tide compared to Sunday morning's low tide. Taken from nearly the same spot you can see the amazing difference. As I understand it, the tidal effect is amplified by the long, narrow, relatively shallow Sea of Cortez, and almost acts like water sloshing up the shallow end of a wading pool.
And of course, with my recent display of 3-D images in our last post, many of the pictures I took were of the stereoscopic kind, where 2 pictures are taken from slightly different angles. Refer back to that post for hints on fusing the pair together - some can see depth in the thumbnails, but click on the image to enlarge it to see the detail. I'll have more soon, but this one will do for now - it shows the shells of little crabs poised on low rocks waiting for the tide to come back in. It is Melinda's current favorite, so check it out!
Labels:
3-D Images,
Roadtrip Stories
Thursday, April 15, 2010
The Blog Now in 3D!
Well, this one post is in 3D, anyway, till I get some feedback! I've been a 3D stereo nut for a couple decades now. We detect depth as a result of our 2 eyes viewing a scene from slightly different angles. So if 2 pictures are taken from different angles, and each picture viewed by each eye, depth can be replicated or simulated. The difficulty is in how to show it to the viewer. All of you don't have the red/blue glasses, and besides, it screws up the color balance. Movie blockbusters these days have complicated 2-projector systems and polarizing glasses, or expensive shuttered glasses restricting each of the 2-image sets to each eye. All are outside the scope of a blog post on your own computer screen.
However, with a little practice, you can see the 3D effect in the enclosed picture pairs. The two shots were taken at slightly different angles, from an inch or two for the cactus to 100 meters or more for the Grand Canyon Isis Temple image. With small pictures, you can look "through" the image to see stereo, but you are limited to little pictures no bigger than your eye separation.
For this post, you need to cross your eyes. View the left image with your right eye, the right image with your left. It is easier than it sounds - don't view too close to the screen - one or two feet away is good to start. Cross your eyes slightly, perhaps tilt your head left-right slightly to align the image, and they should pop together - you will see 3 images, with the center one in 3D showing depth! The cactus one is my favorite, the Fermilab sculpture is likely the hardest, the Canyon shot the neatest. You might try fusing the thumbnails before clicking them for the full-size version - the smaller images require less crossing of the eyes.
Feel free to comment with your feedback, or click on my name at upper right of the blog to send an e-mail and let me know if you were successful - if so I'll take and post more! I'm not responsible for headaches, but give it a try!
However, with a little practice, you can see the 3D effect in the enclosed picture pairs. The two shots were taken at slightly different angles, from an inch or two for the cactus to 100 meters or more for the Grand Canyon Isis Temple image. With small pictures, you can look "through" the image to see stereo, but you are limited to little pictures no bigger than your eye separation.
For this post, you need to cross your eyes. View the left image with your right eye, the right image with your left. It is easier than it sounds - don't view too close to the screen - one or two feet away is good to start. Cross your eyes slightly, perhaps tilt your head left-right slightly to align the image, and they should pop together - you will see 3 images, with the center one in 3D showing depth! The cactus one is my favorite, the Fermilab sculpture is likely the hardest, the Canyon shot the neatest. You might try fusing the thumbnails before clicking them for the full-size version - the smaller images require less crossing of the eyes.
Feel free to comment with your feedback, or click on my name at upper right of the blog to send an e-mail and let me know if you were successful - if so I'll take and post more! I'm not responsible for headaches, but give it a try!
Labels:
3-D Images,
Photography general
Wednesday, April 14, 2010
Star Party at TIMPA for a few friends
My former UMC friend, Vanessa, came into town to visit her Tucson friends this week. When she was planning her visit, she asked if we would take her out observing for an evening. She had never gotten to do that when she was living here - and now lives in Quincy, Mass. - where she can usually see Orion's belt from her balcony. We were happy to oblige, planning for last evening well in advance and keeping fingers crossed for clear skies! For this outing, the Nurses outnumbered the non-Nurses (for a change)! A few more friends joined in the excursion out to the TAAA nearby 'dark sky site' - TIMPA, and I think that fun was had by all! Pictured left, we are: Frank Koch, Vanessa Young RN, Ben Jeffrey RN, Melinda Ketelsen RN, Dean Ketelsen, Jenny Koch RN, and Roger Ceragioli. While you would think that having all of these Nurses would have been an advantage in the event of a snake bite or other injury - we all are NICU Nurses, so not in the habit of working on people older than about 6 months old!
Early in the evening we enjoyed looking at Venus and Mercury (the crescent getting skinnier by the day). You can easily see Venus in the background of this picture of Vanessa looking through the C-14 (and Mercury faintly visible "through" Roger's head as he moved). We actually watched Venus as it set behind the mountains, looking much like a very bright sodium vapor street light before blinking out. It was a good night for showing the planets - Mercury, Venus, Mars, Saturn (with three moons visible), and of course - Earth (duh)! We were also able to show off the Orion Nebula, Crab Nebula, as well as various galaxies and open and globular star clusters.
Here, Roger is giving Vanessa a 'sky tour', using a green laser to point out Aldebaran and the Hyades...then 'connecting the dots' to form Taurus. In addition to Dean's C14, we also set up an 8" telescope and had a pair of binocs for easier viewing of the Pleiades. Even though it was dark of the moon, there is significant sky glow at TIMPA. That makes it difficult to observe some of the fainter objects. It was a good starting point, though, for dipping ones toes into the wading pool of the Universe!
Early in the evening we enjoyed looking at Venus and Mercury (the crescent getting skinnier by the day). You can easily see Venus in the background of this picture of Vanessa looking through the C-14 (and Mercury faintly visible "through" Roger's head as he moved). We actually watched Venus as it set behind the mountains, looking much like a very bright sodium vapor street light before blinking out. It was a good night for showing the planets - Mercury, Venus, Mars, Saturn (with three moons visible), and of course - Earth (duh)! We were also able to show off the Orion Nebula, Crab Nebula, as well as various galaxies and open and globular star clusters.
Here, Roger is giving Vanessa a 'sky tour', using a green laser to point out Aldebaran and the Hyades...then 'connecting the dots' to form Taurus. In addition to Dean's C14, we also set up an 8" telescope and had a pair of binocs for easier viewing of the Pleiades. Even though it was dark of the moon, there is significant sky glow at TIMPA. That makes it difficult to observe some of the fainter objects. It was a good starting point, though, for dipping ones toes into the wading pool of the Universe!
Labels:
Astronomy-general,
Friends
Tuesday, April 13, 2010
Finished Perfection!
I make precision optics for a living. While a small 6" telescope mirror curve can be roughed out, ground, polished, and suitably accurate for a telescope can be done in a week, the near-30 foot behemoths we do at work go on for years! Generally, the start of a project to finish including the casting take 4 years or more. So while it seems our current projects have been going on a long time, it is nice to congratulate others in finishing a project.
I've blogged once before about the Optical Sciences Center, their optics shop, and the project known at the Discovery Channel Telescope. Since that last post, I've heard "through the grapevine" that the mirror was now finished, so I ambled over yesterday when I had a few moments to check it out. The rumors are true, the testing has been completed, and the final reports are nearing completion. The shipping box is having some slight modifications before loading and shipping to Flagstaff in a couple weeks. Eventually it will be installed in a telescope SE of there, becoming the 6th largest telescope in the continental US.
While I'm not privy to the final report, the engineer indicated it fully met the specifications, and while you didn't hear it from me, 80% of the light will fall into a .08 arcsecond circle. That is indeed very good for a telescope of that size.
What made this mirror more difficult is that the design chose to use a very thin mirror - only 1/40th of the mirror diameter. It is difficult to polish a smooth surface on such a thin, flexible mirror. Of course, you can take advantage of this flexibility by bending out some of the optical aberrations by using active optics applied through the 120 or so supports you can see through the telescope mirror. While polished with passive, hydraulic supports, when installed in the telescope, computer controlled supports that can slightly push and pull at the supports will correct minuscule figure errors, and correct support errors as the telescope moves across the sky. With the allowed bending errors subtracted, the residual errors are about 16nm rms, 16 millionths of a mm. Numbers this small are difficult to understand - the standard comparison is if you stretch the mirror from Atlantic to Pacific, the average height errors in the precision surface of this mirror would be about 20mm high, just over 3/4".
While the Optical Sciences Center's Optics Shop isn't "the competition", I take pride in their accomplishments, since I used to work there. Congratulations on a job well done!
I've blogged once before about the Optical Sciences Center, their optics shop, and the project known at the Discovery Channel Telescope. Since that last post, I've heard "through the grapevine" that the mirror was now finished, so I ambled over yesterday when I had a few moments to check it out. The rumors are true, the testing has been completed, and the final reports are nearing completion. The shipping box is having some slight modifications before loading and shipping to Flagstaff in a couple weeks. Eventually it will be installed in a telescope SE of there, becoming the 6th largest telescope in the continental US.
While I'm not privy to the final report, the engineer indicated it fully met the specifications, and while you didn't hear it from me, 80% of the light will fall into a .08 arcsecond circle. That is indeed very good for a telescope of that size.
What made this mirror more difficult is that the design chose to use a very thin mirror - only 1/40th of the mirror diameter. It is difficult to polish a smooth surface on such a thin, flexible mirror. Of course, you can take advantage of this flexibility by bending out some of the optical aberrations by using active optics applied through the 120 or so supports you can see through the telescope mirror. While polished with passive, hydraulic supports, when installed in the telescope, computer controlled supports that can slightly push and pull at the supports will correct minuscule figure errors, and correct support errors as the telescope moves across the sky. With the allowed bending errors subtracted, the residual errors are about 16nm rms, 16 millionths of a mm. Numbers this small are difficult to understand - the standard comparison is if you stretch the mirror from Atlantic to Pacific, the average height errors in the precision surface of this mirror would be about 20mm high, just over 3/4".
While the Optical Sciences Center's Optics Shop isn't "the competition", I take pride in their accomplishments, since I used to work there. Congratulations on a job well done!
Monday, April 12, 2010
Spring blossoms in the desert
The one aspect of our recent trip to Mexico that Dean didn't touch on, in his entries to the blog, was the Spring bloom that we witnessed in the desert. Even though I have been in Arizona long enough to have seen the wildflowers blooming, I actually hadn't gotten to see them until this year. The desert wildflowers typically bloom in late February or early March. This year we had significant amounts of rain during February and the beginning of March (as well as a little cooler than usual temperatures). As a result, the wildflower bloom was delayed until the beginning of April - which was great luck for us!
We stopped at spot west of Kitt Peak to take some pictures, where we had a safe pull off of the road. The bright colors of the poppies are spectacular against the usual brown of the earth. The trees were starting to get their leaves, as well! I've been missing the Spring bloom of the upper Mid-West (hearing from my sisters about the Daffodils and "Blue Cindy's" that are bursting out everywhere). It was nice to see the bright colors and know that even the desert has a season of new life!
We stopped at spot west of Kitt Peak to take some pictures, where we had a safe pull off of the road. The bright colors of the poppies are spectacular against the usual brown of the earth. The trees were starting to get their leaves, as well! I've been missing the Spring bloom of the upper Mid-West (hearing from my sisters about the Daffodils and "Blue Cindy's" that are bursting out everywhere). It was nice to see the bright colors and know that even the desert has a season of new life!
Labels:
Arizona blossoms
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