Archive for the 'Lowell' Category

Coconino Forest Flowers Near The DCT

July 09th, 2010 | Category: Arizona,Lowell

Arizona’s forests are so pretty during flower season! Every other half-acre is a charmed meadow sprinkled with flowers of all hues.  Nobody plants them; they grow wild everywhere.  It’s been like this for about 3 weeks now.  During the “golden hour” it will take your breath away as the angled light transfixes the blossoms and spatters the forest floor with long beams of our star’s light.  All of these images were taken within a mile of the Discovery Channel Telescope.













Bob’s Telescope Tour

February 28th, 2010 | Category: Arizona,Lowell

My Father-in-law Bob visited and I gave him the grand tour of Lowell’s Telescopes. Here are a few shots of the two of us and some of Lowell Observatory’s telescopes.


The Discovery Channel Telescope (DCT) perching on its ridge in Happy Jack, Arizona. This is “my” telescope.


Bob standing in front of the DCT.


Bob standing inside of the DCT dome.  The black machine next to him is a man-lift that will be used for maintenance when the telescope is in operation.  The telescope is not here yet, but the building and the dome are completed. The dome weighs 330,000 pounds; the telescope will weigh a little more.


The electronics that spin the dome. Among other things, I’m working on the firmware that controls this system. The four motors use 480 volts, but can be controlled very precisely.


The Perkins Telescope.

Dr. Dierdre Hunter and Predoctoral Fellow Hongxin Zhang were using the Perkins that night, but were kind enough to let us fool around taking pictures. They are studying dwarf galaxies in an effort to learn more about star formation.




The John Hall Telescope.


The dome of the John Hall telescope in the moonlight.

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Telescope developments and Sedona

September 11th, 2009 | Category: Arizona,Lowell

Recently my Dad and his family visited, so I took them out to see the Discovery Channel Telescope (DCT)  site.  Below you can see a couple of views of the telescope and the mirror coating chamber.  The chamber will be used to put an aluminum coating on the mirror; the coating will be only a few molecules thick.  When in the telescope, it will be open to the elements (when it’s being used) and not protected from dust by anything other than occasional blasts of cleaning gases. So every so often, it will have to have the aluminum coating replaced.  The mirror will be removed from the telescope, transported on rails into the auxiliary building, washed with acids and put into the chamber, where under a vacuum we’ll vaporize some aluminum filaments, coating the glass with the metal.  The layer of aluminum will be 400 atoms thick.


After visiting the telescope we went to Sedona and watched the sun set.  A nearby forest fire created a dramatic sunset.

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A visit to Anderson Mesa

July 16th, 2009 | Category: Arizona,Lowell

My sister and brother-in-law visited and I wanted to show them some cool science stuff, so we went out to the Anderson mesa where Lowell has its current research telescopes.  This area is not open to the public, so it was a real treat.  Of course, I’ve been there many times, but it always excites me.  These telescopes are a little antiquated and small by modern standards, but still very impressive.  Real science is produced here every year, even every day.  Scientists use these instruments to look for near-earth asteroids, comets, examine the atmospheres of planets, and to look for planets around other stars.

Here’s the LONEOS 25-inch telescope dome.


The LONEOS telescope.


My brother-in-law David near the scope.


The 72-inch Perkins telescope.  The man in the red shirt is Bruce Koehn, Observer and telescope operator extraordinaire.



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Telescope building looking more and more finished

June 22nd, 2009 | Category: Lowell,Work

I’ve been too busy to be creative, so here’s a link.

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Letter to friends

June 07th, 2009 | Category: Arizona,Lowell,Work

Here is a letter I sent to friends recently – I’ll put it here as a catch-all for people I might have missed.

Greetings all!

If you find anyone that I’ve left off of this email, please forward it to them. Omission from this list is accidental!

It has been a few months since I left the Lab and I have been thinking about all of you. After a 6-week marathon session of home refurbishing, car purchasing and all kinds of last-minute details, we (Holly and myself) rented our house to a great lady (who is taking care of our dog) and hit the road. We drove for about two weeks, eventually landing up in Flagstaff, AZ. Along the way, we stopped to see the creation museum in Kentucky (it was like the twighlight zone), Arches national park, monument Valley, many smaller parks, friends along the way, and of course too many interesting roadside sights to mention here. The trip length was 2900 miles.

I have been at my new job for three weeks. The assignment is as challenging as any I have faced at JHUAPL, but the conditions of work are very different. Lowell Observatory is like a big family. There are only 80 people on staff. Everyone knows everyone else. Although I have many tasks, they are all for the same project. I don’t have to worry about what I’m going to be doing next month, and don’t have to fill out a weekly time sheet. Among the staff, there is a sense of work/life balance, but also an intense feeling of dedication to the work and to the institution. There is a sense that the work is important, and a sense of the history of the institution. The campus is situated within a national forest on a small pine-covered mountain overlooking Flagstaff at 7300 feet. There are breathtaking views of mountains and many animals around the place. It is dog-friendly and some people bring dogs to work. In three weeks, I’ve purchased one tank of gas, and probably won’t need another one for a week or two unless I go on a trip.

We have been living in temporary quarters in a historic building on campus; the building is filled with historical curiosities dating back to the 1890s when Percival Lowell began his investigations on the planet Mars. We’ve found a special apartment of our own, less than a mile away from Lowell, and will soon move into it. The observatory is the local center of public science education, in the same way as the Baltimore aquarium (only smaller), so there is a constant stream of visitors. The facilities are open until after dark, and if the weather is good and the sky clear (which it usually is) visitors can look through the historic 24-inch telescope which dates back to 1896. Flagstaff has just the right balance of small-town and large-town features. The place has an old town district with many locally-owned businesses, restaurants and art galleries. On the outskirts there is a wal-mart, supermarkets, etc. It is a resort town, but with all the conveniences needed. The grand canyon is 1.5 hours away. Many of the country’s most famous national parks (Zion, Canyon de Chelley, Meteor crater, petrified forest, etc.) are weekend trips. It is a very outdoorsy society and almost everyone you see is athletic and tanned, but in a mountain way, not a Miami way. The city is full of trails; mountain biking, climbing and skiing are big here. In the summer, people come from the desert cities (Phoenix, Tuscon, etc.) to get out of the heat. In the winter, people in Flagstaff can be in the desert in an hour or so to get some alternative weather. Simply walking around the streets on an errand, you can see breathtaking sights like a pink sunset over volcanoes. Like any place it has some problems (traffic from tourists, transient homeless, the danger of urban sprawl) but there is nothing like this in Maryland, even counting the wonderful eastern shore and mountainous western portion of the state.

When I left I promised I’d keep up with my friends back home. Although you are out of sight, you are definitely not out of mind. I am still in the process of processing pictures and writing about our adventures, but some of them are on my blog. Here are the main links. If you’d like to keep up to date, take a look at the blog periodically. I post something at least every week, and will be posting about our trip out here for weeks to come. (the blog main page) (daily maps of progress and short descriptions of that day, keep hitting “next”) (creation museum, this stirred up a minor controversy. See comments at end of post, and also ) (St. Louis) (monument valley) (the telescope) and (pictures of where we live)

Fondly, Dan


The Discovery Channel Telescope (DCT)

June 07th, 2009 | Category: Lowell,Work

Recently there was a Lowell Observatory Advisory board meeting.  A couple of my colleagues and myself gave tours of the construction site to  board members.  The discovery channel telescope ( or DCT, so named because of significant funding from that television channel) is being built on a mesa near Happy jack, AZ.

You can see that the building is in an advanced state of construction; the telescope itself is not yet completed and is not yet inside.


The portion on top that is mostly girders – “the dome” will weigh about 1/3 of a million pounds when complete.  It will be turned by four electric motors.  The telescope is a leviathan that will weigh some 145000 pounds and sit on its own bearing and have its own motors.  The dome and telescope will turn together in separate but synchronized motion.


The telescope and the interior of the dome must be kept at the same temperature as outside so that there are no thermal disturbances which will mess up the optical seeing.  To do this, the building has many vent doors which can be opened, as well as active liquid cooling that will control the temperature of the telescope’s mirrors.  Also, air will be drawn through the tubular support structure of the telescope as well as the mirror mount.

Here are a couple pictures of me during the tour, taken by Holly.



Here I am explaining the Active Optics System (AOS).  It is not designed to correct atmospheric distortions, but to control the shape of the main mirror while the telescope moves around. Although the mirror is made of ultra-low-expansion glass, and a chunk of it would seem rigid, you can think of it as a blanket of glass.  It weighs 6,700 lbs is about 4.2 meters – 14 feet – across and only 10 cm thick.  So, as it moves, it wrinkles and sags.  You can not see this with the naked eye, but since the mirror needs to be maintained in shape by only a fraction of a wavelength of light (less than 1 millionth of a meter), it is a problem.  To counteract this, there are mechanical “pushers” around the periphery and underneath the mirror.  These components push, pull and lift the mirror to maintain its shape.  The mirror is not bolted to its mount, because that  would distort the surface to the mirror and thus the resulting image.  It is made to slide around while the mechanical compensators keep it in shape and in the right position.

I am pointing at an engineering drawing of the mirror on its mount.  To my right is a rendering of the telescope which will sit inside the dome.  I’ll really have to get some JPEGS to post here.


Inside the dome, under construction.


One of the numerous dome bearings that will support the enormous mass of the dome structure and allow it to turn smoothly.


View looking up from the mezzanine level.  The temporary wooden structure fills the space that will be occupied by the telescope.


View of the landscape around the telescope site.  It’s in the coconino national forest north of Phoenix.


The day’s pictures (including some already shown above):

For “official” photos of the site as well an engineering documents and more, see here.

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Uncle Percy’s attic

June 07th, 2009 | Category: Lowell

We’re lodged in the Slipher building at Lowell observatory.  It is one of the older buildings at the here – a wonderful old creaking mansion, built in the early 1900s from local stone and ponderosa pine.  It’s filled with fireplaces, multiple stairways, wood paneling, and period furniture.  The window glass is wrinkled; its large attic is stuffed with historical curiosities.

Don’t forget that you can click on any of these images to see larger versions.

On the first night, I explored the entire building from top to bottom.  The attic was by far the most fantastic place.  Although the rotunda of the building houses Percival Lowell’s library and a number of historical astronomical instruments (like the blink comparator used to find Pluto), a large quantity of material lies out of public view.  Creeping around in that attic late at night with only a flashlight, I felt like I was in a Harry Potter movie.  Cobwebs were draped across ancient wooden telescope cameras; shadowed corners divulged piles of glass plates bearing images of mars exposed at the dawn of the last century.  90-year-old notes scratched with fountain pens described the contents of disintegrating crates of handwritten data.  Handmade, 19th-century brass machinery gleamed dully in the feeble light from the unevenly spaced bulbs.  Good thing I had a flashlight.  I wiped a thick rime of dust from the manufacturer’s plate on a primitive-looking electric telescope drive; it was patented (and manufactured) around 1900.  Less antique but still dated tube-based equipment also piqued my interest, as did a box of mariner 9 data.

I went back in the day time to make use of the beautiful dusty light.


The intriguing stairway upwards…


As you go up, you can see the inside curve of the rotunda.




In seemingly endless shelves lining the attic, a jumble of astronomic history sits awaiting display by future curators.  At lower left, a portrait of Percival Lowell glares sternly at me and my camera.


In dozens of boxes, historical artifacts lie in a semi-organized jumble.


The label on this box of glass plates reads “Negative enlargement of Mars and pro-mars arranged in order of original films.”  The date on the box is 1922.


Carefully opening the box and gingerly holding the plate up to the light, I could see an image of mars used in research almost 50 years before I was born, and about 90 years ago.  In the intervening years, many spacecraft have orbited Mars, and several robots have landed and even crawled around on its surface.  If only those early astronomers could have seen the data we have!  What they labored to learn, squinting through primitive telescopes, imagining the details of this distant and blurry planet, was only a fraction of the larger understanding we now have; but the modern knowledge would not have been possible without their pioneering labor.


Here are some primitive filters used for photographing mars (and probably other objects).  The one on top reads “To measure apparent brightness of Mars.”



I’m not sure what this is – probably a small blink comparator, or a device for close inspection of photographic plates.  It has the look of old machinery, made by hand with brass fittings.


A box of Mariner 9 data from 1972.  Notice the small sign tacked to a beam – it says “Photographic equipment – ‘old’.”


Here is some of that photographic equipment, made of wood and brass and with an enormous bellows.  Lying on top and around this camera (known as an “astrograph”) are the carriers for the  enormous glass negative plates of approximately 10’x14′.  Glass plates date from the earliest days pf photography, before there was cheap celluloid film.  They continued to be useful for some time after the invention of celluloid because the rigid glass maintained the flatness of large glass plates.  I don’t know how old these are, but I’m guessing they date from before 1915.  Matthew Brady used similar equipment to photograph the civil war.



A primitive-looking reflector telescope made of riveted struts, and with brass fittings.  Any time I see a metal construction with brass and no welds, I suspect that its old; welding wasn’t commonly used priot to 1930, specially in one-off custom pieces like this.  Brass is not often used in the modern era; aluminum has largely replaced it.


If you look closely, you can see the reflection of me and my camera.


An antique vacuum pump, probably used to evacuate spectroscopy tubes.  It has a leather belt and a wooden base.  They don’t make ’em like that any more!


The manufacturer’s plate on the motor.  The patent date is 1900; based on the appearance and other objects attached to it, I’m guessing that the motor was made around than 1915 (the patent date of 1900 does not reflect the manufacture date, which is always later).


This mysterious and ancient-looking mechanism was sitting on top of a piece of modern electronics when I found it.  I put it on the floor to photograph it, then carefully replaced it.  It seems to be some kind of synchronized reflector.


A large telescope lens found lying amidst a pile of picnic equipment.


Finally, the iconic painting of Percival Lowell gazing through his signature Clark telescope.  This painting has been reproduced many times on various promotional materials.  It is really quite good; it was painted by Flasgstaff junior high school students in 1980.




June 07th, 2009 | Category: animals,Arizona,Lowell

The grounds at Lowell are filled with Hummingbirds.  They are broad-tailed hummers, a species not found on the east coast, although they look almost identical to the ruby-throated hummers found on the eastern seaboard.  They have a distinctive metallic “churr” as they fly.  They are bold and extremely territorial, and will not hesitate to swoop down on a person in order to chase them away!

This guy always perches on the same branch of the same tree, where he periodically asserts his dominance by making fantastic flights up to high altitudes before plunging at high speed almost to the ground in great, looping dives.

In the scenic image, you can just barely see him at the center, a miniature bird-shaped dot.  These animals sooo tiny.

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Todd’s visit and the Clark telescope

June 07th, 2009 | Category: Arizona,Lowell

My good friend Todd was on a business trip and was able to stop by.  Here he is with Holly, as the overlook at the entrance to Lowell Observatory.  In the background to the right, you can see a hint of a rainbow.


After dark we walked over to the Clark Telescope, and had a great view of Saturn.  This telescope is no longer used for research and is of historical interest only.  We are using, and building much larger telescopes!


If you look at the next picture in darkness and allow your eyes to adjust you can see the moonlight on the dome and stars in the sky.


The 24-inch barrel of the clark telescope, made in 1894, points out of the wooden dome like a giant cannon.  The woodwork is complex and beautiful, although meant to be utilitarian.



Here are some images inside the rotunda, which has been turned into a museum of artifacts from the early days of work here.  Among the interesting items are the blink comparator used to find Pluto, and some early spectroscopic equipment used to show that most observable objects in the universe are receding from us, supporting the “big bang” theory.




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