December/January 2000/2001 Issue
From the President's Desk
by Richard Greiner
With this issue of the News letter, you will find an en closure of considerable importance. It is a copy of the revised by-laws for the Madison Astronomical Society. Many small modifications have been made which range from correcting grammatical errors to improving consistency of references to the membership and offices within the document.
Several larger changes have been made as well. The ad hoc by-laws committee met twice for a total of almost 10 hours. The committee consisted of the officers and board of directors of the MAS with the addition of two members at large. We as a group believe we were meticulous in creating this revision.
Please read it carefully. As required by the current by-laws, this document is being distributed to all members at least one month before it is acted upon by the general assembly of the MAS. Action will be called for at the regular January meeting of the Society. If you have any concerns bring them to the January meeting for discussion.
I thank the members of the by-laws committee for their diligent efforts.
On other matters, my message is very short. We have had several excellent, interesting and exciting speakers already this Fall. Approval of our operating budget at the November meeting showed that the Society is in good financial shape. We have added a few regular members and a few additional members have converted to observation status.
I wish you kind thoughts for the Holiday season and encourage you to join us at the December Holiday party. Join us in bringing refreshments and sharing them along with Holiday spirits.
The annual Holiday Party will be held in lieu of the December regular meeting. Join us on Friday night, December 8 at Space Place for some informal socializing. Bring a drink or treat to share.
Just before this issue went to press we received the very sad news of the death of Dan Strome's son David in a drowning accident. MAS extends our deep and heartfelt sympathy to Dan, his wife Therese and daughter Rebecca. Dan and family, our thoughts are with you.
December 8: MAS annual Christmas party. Bring a treat or drink to share, come to enjoy some holiday cheer. 7:00 pm, Space Place, 1605 S. Park St.
December 20: MMSD Planetarium: Season of Light, multicultural holiday program, 5:30, 6:45, 8:00, Memorial High School, corner of Gammon and Mineral Point. 829-4053 for info.
January 12: MAS monthly meeting: Getting started with astrophotography. Visitor/beginner meeting at 7:00, main meeting at 7:30. Space Place, 1605 S. Park St.
January 16: Good Neighbor Lighting Group meets to combat light pollution, MMSD Planetarium, 7:00 pm, Memorial High School, corner of Gammon and Mineral Point. 246-0222 for info.
January 17: MMSD Planetarium: Skywatching, 6:30 and 7:45, Memorial High School, corner of Gammon and Mineral Point. 829-4053 for info.
Professor Anderson Speaks on SALT
by Wynn Wacker
On Friday, Oct. 13th, the Madison Astronomical Society had the good luck to hear a presentation by Prof. Christopher M. Anderson, Chairman of the University of Wisconsin Astronomy Department, on the Southern African Large Telescope (SALT). This is a state-of-the-art spectroscopic telescope to be constructed in South Africa at the site of the South Africa Astronomical Observatory. The UW is committed to providing $4.8 million to the project and is the largest U.S. contributor (though Carnage-Mellon is a competitive close second).
SALT will be an 11-meter aperture telescope specialized for spectroscopic measurement (so don't expect a lot of pretty pictures). It is in many ways similar to the newly constructed University of Texas Hobby-Eberly Telescope, though hopefully benefiting from the "learning experiences" of that project. It is designed to get the maximum "bang for the buck", and incorporates a number of short-cuts made possible by swapping sophistication in detector design for big-ticket support structures. For example, much like the Areceibo radio dish, the mirror does not change it's tilt. Instead, the detector housing moves as the object image is carried along by the Earth's rotation. This eliminates the complex structures needed to correct for sag when a large mirror is tilted, as well as the heavy axis and mountings needed for the motion. However, the mirror tilt of 37° is combined with the ability to rotate in azimuth giving the telescope access to about 75% of the sky. The combination of detector and telescope motion will allow objects to be followed for from 2 hrs to 4-5 hrs, depending on their declination. Another savings is in the use of spherical hexagonal mirror segments to make up the main mirror, rather than the traditional paraboloidal ones. This means that the segments are interchangeable and can be swapped out for resurfacing. The mirror segments are kept in the proper plane by sophisticated mechanical actuators, and the spherical aberration will be corrected at the detector.
The real sophistication of the project lies in the detector. The hexapod prime focus tracker mounted on the dome slit must simultaneously move in six directions with high precision to follow the image. The high-tech heart of the project, and the contribution from the UW, is the prime-focus imaging spectrograph (PFIS). Because it is high and hard to reach, the detector is considered a remote site and our Space Astronomy Laboratory's experience in designing remote-operated instruments was reason the UW's participation was solicited. There are actually modes for the spectrograph. The most precise spectral measurements will use a sophisticated (and expensive) Fabry-Perot etalon tunable interferometric filter built at Rutgers. Getting the maximum photons over the entire detector range from 3100 Å 8700 Å requires lenses constructed of such exotic elements as silica, CaF2, and NaCl (yes- there's actually some salt in the SALT telescope!). The other mode substitutes a volume phase holographic (VPH) grating for the etalon, permitting entire spectra to be sampled simultaneously. The VPH is superior to a standard diffraction grating in that more of the light goes into the first-order spectrum.
As is usual, telescope time will be allotted in proportion to the participant's contribution to the project, and the UW's efforts will insure that astronomers from flat and cloudy Madison will have the chance to do cutting-edge spectrographic research in the relatively under-studied southern heavens. Lest anyone have a lingering bad taste from the apartheid policies of the previous South African regime, they should know that this is flagship technological project being promoted by the current government, which is picking up half the $35 million cost. It is designed to develop local technological infrastructure and encourage research participation by all the countries of southern Africa. As the head of the project says, research needs to be something done by Africans and not for Africans by Europeans and others.
For more information, check out:
The December 25 partial solar eclipse
Late this month, on Christmas day, a partial solar eclipse will be visible from the United States (except Alaska and Hawaii), Canada, Mexico, Central America, the Caribbean and the North Atlantic. In Madison, approximately 56% of the sun's disk will be covered at greatest eclipse. Since the central part of the moon's shadow, the umbra, misses the earth entirely, there will be no "total" eclipse visible on this, the last eclipse of the millennium.
For observers in Madison, the partial eclipse begins at about 9:43 AM, reaches maximum at 11:18 AM, and ends at 12:48 PM. Even though a little more than half the sun's disk will be obscured, the actual drop in light levels will be virtually unnoticeable. Unless you're watching the sun, you won't notice anything at all. There will be no daytime roosting of birds, no unusual animal behavior, no drop in air temperature - all events regularly reported by observers of total solar eclipses. This plus the fact that it happens on the morning of Christmas may conspire to make it a relatively unobserved event. Many may find it difficult to break away from family get-togethers and holiday celebrations. If you get clouded out or just can't get an opportunity to view this eclipse, you'll have a few more chances in the next several years. Madisonians will see partial eclipses on December 14, 2001, June 10, 2002, May 20, 2012, and October 23, 2014, but these will all be very late afternoon events, where the sun will actually set while in a partially eclipsed state. This month's event is visible from beginning to end while the sun is high in the sky.
The big enchilada is coming up on August 21, 2017 - the next opportunity for the continental United States to view a total solar eclipse. The path of totality will follow a line from Oregon to South Carolina. Madison observers will see a deep partial eclipse but most diehard observers will want to drive to southern Illinois or Missouri to see totality. Mark your calendars.
From the Observatory Director
The R. A. "Doc" Greiner observatory is back in service. MAS president Doc Greiner generously replaced the damaged controller cards in the telescope drive, returning the instrument to full functioning status. I am reminding everyone that nothing may be either plugged in or unplugged from the drive unit without first shutting off the power. This means that if you wish to operate the scope from a notebook computer or if you simply want to remove the dedicated control pad, you must first switch off the telescope (the same switch that puts the "Doc" Greiner observatory into operation). Disregarding this rule will likely result in more damage to the telescope controls.
Now that the cold months are here, I am reminding everyone that when you first open the clubhouse and wish to warm things up a bit, simply set some time on the heating timer on the floor just below the air conditioner. All other heat controls are left permanently at the desired settings. The clubhouse will rapidly warm up to a sustained temperature of about 68 degrees. Maintenance level heating will otherwise keep the clubhouse at a steady 48 degrees or so. The only heat control that anyone should use is the timer. If the timer is still running when you leave, please turn it back to zero.
The Yanna Research Station got it's last lawn mowing of the season a few weeks ago. The Deer Mice were frolicking to and fro. I suggest that we all keep on the lookout for them when opening up observatory buildings during these Winter months. Anyone using the facilities should check to see that throwaway mouse traps are in place.
MAS welcomes new member Joe Hermolin. Donations received this month from Doris Koster, Howard Bixby, Terry Young, and Tom Brissette.
Please note that the Spring Banquet will be at DeLaney's on Grand Canyon Drive on Friday, April 20. We will be in a party room with a bar, similar to what we've had at CJ's the past few years. Look for more info about the banquet in an upcoming issue.
Reflection of Genius
by William Jollie
Wisconsin lost one of its great astronomers as autumn skies rolled into view. Herbert Swoboda passed on late Friday night, September 29, 2000.
I never met Herbert Swoboda, but I got to know him, briefly and not well enough. I work with his grand daughter, and one evening as we were leaving the building Angela said "I told my grandfather about your interest in astronomy, and the great telescope you own, and he wants me to show you one of his."
"OK, love to see it," I replied, mildly curious. I figured it was another modest commercial scope, but it might be an old modest commercial scope.
She opened the trunk of her car. WOW. The scope was medium aperture, a 4.5-inch reflector. But it was a thing of beauty. It had obviously been designed and built by a single informed passion, not a company. But you couldn't call it home made. The aluminum tube and its odd handle mount were extremely well formed, fitted and finished. The scope mounted on one's shoulder, looking like a bazooka. I'd never seen anything like it before.
"Can I try it?"
"Sure. My grandfather loves to make things. He made four of these, for his grandkids and their friends."
Four of these. And from Angela's casual tone this accomplishment wasn't at all unusual. "He ground and polished the mirrors, did all the metal work. He's made a lot of telescopes."
I shouldered the scope. Well balanced, and the shoulder mount felt just right. "This guy knows human and metal engineering," I thought. I aimed across the street and peered through the custom helical focuser. WOW. This guy knows optics, too. I looked around for sunlight glint off a car hood: the closest "star test" I was going to get at the moment. Peering through the focuser (crisp, smooth actionand easy to accomplish focus even with the scope balanced on my right shoulder) I saw a brilliant, pinpoint of light; no misfiguring, coma, or smear.
"Look, here's a sun watching telescope he made." The brass refractor mounted a 2.5-inch lens with a screw on glass solar filter in a brass mount. Don't remember seeing those in the Orion catalogueThe machining on the brass and its alt-az mount was exquisite. The rack and pinion focuser had obviously been designed to fit this scope and no other, with artful bevels to match the flair at the helioscope's business end. I resisted the urge to run into the street and stop traffic so I could check for sunspots before the sun dipped below a building.
"Um, Angela, do you think I could call him and tell him how much I admire his instruments. Your Grandfather is a master craftsman."
"I'm sure he'd love to speak with you. He's invented things all his life. He's really old now, and sick. But he loves to talk about telescopes."
And so began my weekly calls to Herbert Swoboda.
"Hello?" The voice was crisp, inquiring and focused. I felt a momentary pang of anxiety. I hadn't rehearsed this first call, I just had a few minutes between putting my child to bed and getting a paper ready for work the next day.
"Uh, good evening Mr. Swoboda. You don't know me, but I work with your grand daughter "
"Oh yes, the telescope owner. Angela told me you might call" The voice was still crisp, but friendly and inviting now. Easy to talk with a man you admired and had never met. And as Herbert Swoboda talked, I admired him more. I didn't get to the paper that night. I glanced off a genius instead.
Swoboda was exuding energy and talking quickly, but distinctly. Yes, Yes the shoulder mount reflectors. All cut from the same blank. He'd made a grinding tool just to figure those mirrors. A friend had done the silvering (the original Clausen). And did I notice how easily the mirror and diagonal could be reversed in the tube? I had not.
"The boys loved that. Thought it was the best part. See, they could go to the beach and pretend to look at boats when really they were looking at the pretty girls behind them. Heh. Heh. Yeah, those are good scopes for the beach."
Well, maybe not politically correct, but Herbert Swoboda loved his kids and any part he could play in their life. And the guy loved glass. And metal, and machining, and electronics, and photography, and bursting through the constraints of ordinary thoughts about the way things worked. Like the army. Along with many men his age, Swoboda served in the Second World War. But when he was posted to Fort Jackson, in South Carolina, he knew where he was. Only a couple of miles from the Melton Memorial Observatory, in Columbia. So he pulled evening KP in order to whiz through his chores, and then steal out at night to meet the observatory director. In a short time he was running their Cassegrain. An impressive instrument, but he tweaked it to the delight of the professionals there. The army got a call. Could they spare Mr. Swoboda on a more regular basis? Heh. Heh.
After the war, he was an aeronautical photographer. He took pictures of Yerkes that can still be seen at the observatory and in their publicity stills. Got to know Mary Cavendish, the operations director, and designed instruments for the Observatory Directors Otto Struve and Gerard Kuiper. Would run the dome when he had the time. Offered a full time job at Yerkes, he turned it down. Too far from family in Green Bay.
Herbert Swoboda loved big glass and fast scopes. He liked to build his own machines to figure and polish big glass. He mounted a 16-inch f4 on his station wagon, so he could run up to Fish Creek in the summer time without hauling a lot of stuff in and out of his car. A traveling observatory with a premier instrument, back when Door County's skies were really dark.
He had designed and built spectography, spectrometry, crystallography, and other scientific research equipment, and I started collecting sand samples to bring him when we finally got together. Green Bay isn't that far from Madison. But he was sick and I was busy. The free weekend I could find here and there wasn't coinciding with his health, which was worsening. Kids soccer, office work, my own aging parents and other distractions intruded when he was feeling good enough to receive visitors.
His mind was still extremely sharp and restlessly active. He explained one night how to build a collimation device he had invented that used several components including a half silvered mirror in its optical tube. I professed my lack of machining skills.
"Well, call the folks at Edmund Scientific, and tell them, this is what you want and how to make it" I am sure the folks at Edmund Scientific would have dropped what they were doing to fill a special order from Herbert Swoboda. Me, a different story.
"Yep, You've got to get the collimation super precise for those big f4s and f3.8s. And that's the best device I ever invented for collimation. You see, it gets all the mirrors exactly lined up along your geometrical axis. Best collimator there is."
"Better than these new laser collimators?"
A pause. The teacher trying to figure out a way to explain something to a slower student who didn't get it the first time.
"Well, you see, the collimation ends up precisely where you put your eye at the eyepiece. Most people have a natural way of standing at the eyepiece and if its only slightly off the geometrical path, the telescope's optical path can still be correct, but with the physiology of your eye, and of course you see so much better when you are at ease with the telescope...it's so fast and easy, you can recollimate for every user if you want to."
The last time I called he opened immediately with, "My grand daughter told me the size of your refractor, and I just want you to know I realize the financial and physical hardship you endure to use that thing. Heh. Heh."
Herbert Swoboda had specific instructions for me at my next star party. And I should get Angela and her shoulder mount refractor out there, too.
"She wants to come see me, but the night sky is so much more interesting, don't you think?"
Not at all, Mr. Swoboda. Not at all.
Professor Linda Sparke looks for dark matter in bizarre "polar-ring" galaxies
At MAS' November meeting, Dr. Linda Sparke, professor of astronomy at UW Madison, gave a talk on the search for dark matter. She opened her presentation with a fascinating picture of NGC4650 (released by the Hubble Heritage project last May), the so-called polar-ring galaxy (picture below). As has been well established, the rotational dynamics of galaxies indicate much more mass than is visible at optical or radio wavelengths. However, most studies of the rotational dynamics of galaxies are able to follow the matter on only one axis. The unusual double axis rotation of 4650 enables Sparke to measure rotational velocities in both axes, thereby learning something about the distribution of dark matter throughout the structure (conclusion? The mass is not distributed spherically). Exactly what caused the unusual shape of 4650 is not clear, says Sparke. It's possible that an interaction with another galaxy perturbed matter in the halo 3 to 5 billion years ago setting off a burst of star formation above the plane of the original disk.
Image Credit: The Hubble Heritage Team (AURA/STScI/NASA)
In general, the gas distribution in a galaxy reveals the distribution of dark matter. The rotational speeds of the gas (visible at radio wavelengths) or the stars (visible at optical wavelengths) do not fall off as you get further from the center, as Newton says they should. Presumably as our instruments get more and more sensitive, and we are able to follow the gas further and further from the core, we will detect this drop-off in rotational velocity, but no definitive findings have been established yet
Oops! Last month's article on the University of Arizona Space Camp carried this photo of David Levy addressing campers. We omitted the credit for this photo. Thanks to Jeff Regester of Wellesley College for snapping the picture and letting us reproduce it!
June 8, 2004 Venus in Transit
by Eli Maor, Princeton Univ Press, February, 2000, hardcover - 186 pages
Reviewed by John Rummel
A delightful short book about an astronomical event both dynamic and rare, and one that has an important place in the history of science. Venus is the closest planet to earth, and having an inferior orbit (closer to the sun than us), can occasionally be seen to cross the face of the sun a transit. Such events can be observed with the naked eye (appropriately filtered) but are relatively rare, occurring in pairs separated by about 8 years, 100 years apart. Only five times in recorded history have Venus transits been observed, and Maor tells the story of each encounter painted in lively narrative against the historical backdrop of the times. From theorist Kepler, whose accurate calculations of the orbits of the planets first permitted accurate prediction, to observers Gassendi and Horrocks in the 17th century, Maor intersperses the story with well written nontechnical explanations of the celestial mechanics that lie behind the transit phenomenon, including the best explanation I have ever read of the reason behind the curious pairing of two transits just 8 years apart, with each pair separated by 100 years or more.
The historical importance comes due to the fact that as astronomers were slowly unraveling the mysteries of the solar system, the absolute distance scale remained elusive. Kepler's 3rd law allowed scientists to compute the relative distances of the planets from the sun, but absolute distances couldn't be obtained unless one knew the exact distance from the sun to the earth. In 1677, Edmund Halley observed a transit of Mercury, and realized that a transit event could serve as an excellent opportunity to obtain measurements of the transiting planet's parallax, from which could be calculated the distance of the transiting body. Then, using Kepler's 3rd law, the distances of all other planets - including the earth - could be calculated. Halley worked on the problem for almost 40 years, and in 1716 published a detailed plan for using the next transit of Venus to determine the size of the solar system. Already 60 when he published his plan, Halley knew he would be long dead before the next transit in 1761, but his scientific stature and eloquent appeal was all that was necessary - when the time came, the scientific world was ready (Halley's posthumous reputation was further enhanced when the periodic comet that now bears his name reappeared in 1758, just as he had predicted).
Alas, Venus transits proved not to be the answer to the scale of the solar system (exact timing of transit events proved unreliable due to Venus's thick atmosphere), but the stories of the explorers who traveled to the corners of the earth in 1761, 1769, 1874 and 1882 are worth the price of the book. Maor concludes by pointing out that the upcoming event in June of 2004 will the only the sixth opportunity in recorded history to observe such an event, and while scientists are no longer watching for the same reasons as two centuries ago, the event will have enormous popular appeal.
Maor's book is wonderfully written, and will be of interest to amateur astronomers as well as those with an interest in the history of science.
A Photographic Atlas of Selected Regions of the Milky Way
by Edward Emerson Barnard. Edited by Edwin B. Frost and Mary R. Calvert. (Carnegie Institution of Washington, 1927).
Reviewed by John Rummel
I requested this two volume set via interlibrary loan, never expecting to receive it due to its age and rarity (replacement costs would be as much as $12,000). About one month later, both volumes arrived at the Middleton library. Barnard's Atlas is an astronomical classic - an important historical work that very few amateur astronomers ever get a chance to examine.
Volume 1 contains 52 original prints produced from Barnard's original negatives, and 31 pages of Barnard's description of each plate. All plates were shot with the 10" and 6.25" Bruce photographic refractors at Yerkes Observatory in Williams Bay Wisconsin, or Mt. Wilson California. The plates themselves have the appearance of original photographic prints mounted on linen pages. The cover and overleaf bear a portrait of Barnard, followed by an introduction to the work by Edwin Frost, and after that an extensive introduction by Barnard. Vol. 2 contains hand drawn charts showing objects of interest on the plates and a listing of the coordinates of the objects on the page facing the chart.
Barnard was a procrastinating perfectionist, and his classic atlas was not published until 20 years after the Carnegie grant 5 years after Barnard himself had died. After his death in 1922, the cause to finish the epic project was taken up by his long-time assistant Mary Calvert and Yerkes' director Edwin Frost.
The books have that authentic "dusty" feel and bear the nameplate of the Washburn Observatory Library on the inside flap. The cover is a cloth-bound hard cover, brown in color. The pages are yellowed and just shy of brittle. Many pages bear light pencil marks, cryptic annotations of researchers lost to the years. Several plates also have what appear to be wax marker imprints, noting the positions of various open clusters, or other items of interest to readers of a generation ago.
Only 700 copies of the atlas were produced, and since Barnard was unsatisfied with any method of reproducing his photos for publication, he personally supervised the printing and inspection of the over 35,000 prints necessary for the publication of his work. As his notes for each plate attest, he was not satisfied fully with the final result; he frequently criticized the prints as being over or underexposed, too bright or too dark, etc.
Photo of both volumes open to the same entry. The top has the photograph on the right and Barnard's description on the left. The bottom (volume 2) has Barnard's hand-drawn chart on the right with a table of stars and objects with coordinates listed at left. Title page and overleaf of the Atlas. Note the impression of Barnard's portrait, in reverse, on the title page. Intentional artistic touch or bleeding of the ink over the years?
Spending two weeks pouring over the beautiful glossy prints of was sheer joy. Barnard wrote a one page description of each plate, with date, exposure time, celestial coordinates, observing location, and a brief title (e.g., region west of Sagittarius). Each page is rich with his descriptive prose and drips with history as he struggled with the nature of the many dark lanes and twisting tendrils of nebulosity, most of which he was the first to examine. All prints bear slight concentric star trailing at the corners, a testament to the length of the exposures. That such wide field shots from that era are as clear as these are is amazing.
This is not a mere book, it is the result of a lifetime's obsession with photographing the sky and capturing the beauty and mystery of astronomy. Barnard's soul is in this book, and its pages speak of his passion better than prose or poetry.
"The Milky Way has always been of the deepest interest to me. My attention was first especially attracted to its peculiar features during the period of my early comet-seeking. Indeed, there is no work in observational astronomy that gives one so great an insight into the actual heavens as that of comet-seeking. The searcher after comets sees more of the beauties of the heavens than any other observer." -E. E. Barnard
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