THE ELECTRONIC JOURNAL OF THE ASTRONOMICAL SOCIETY OF THE ATLANTIC Volume 3, Number 11 - June 1992 ########################### TABLE OF CONTENTS ########################### * ASA Membership and Article Submission Information * History of the Ohio SETI Program - Robert S. Dixon * The Hyades: A Star Cluster Rich in Myth and Astronomy - Ken Poshedly and Don Barry ########################### ASA MEMBERSHIP INFORMATION The Electronic Journal of the Astronomical Society of the Atlantic (EJASA) is published monthly by the Astronomical Society of the Atlantic, Incorporated. The ASA is a non-profit organization dedicated to the advancement of amateur and professional astronomy and space exploration, as well as the social and educational needs of its members. ASA membership application is open to all with an interest in astronomy and space exploration. Members receive the Journal of the ASA (hardcopy sent through United States Mail - Not a duplicate of this Electronic Journal) and the Astronomical League's REFLECTOR magazine. Members may also purchase discount subscriptions to ASTRONOMY and SKY & TELESCOPE magazines. For information on membership, you may contact the Society at any of the following addresses: Astronomical Society of the Atlantic (ASA) c/o Center for High Angular Resolution Astronomy (CHARA) Georgia State University (GSU) Atlanta, Georgia 30303 U.S.A. asa@chara.gsu.edu ASA BBS: (404) 564-9623, 300/1200/2400 Baud. NEW TELEPHONE NUMBER or telephone the Society Recording at (404) 264-0451 to leave your address and/or receive the latest Society news. ASA Officers and Council - President - Don Barry Vice President - Nils Turner Secretary - Ingrid Siegert-Tanghe Treasurer - Mike Burkhead Directors - Bill Bagnuolo, Eric Greene, Tano Scigliano Council - Bill Bagnuolo, Bill Black, Mike Burkhead, Frank Guyton, Larry Klaes, Ken Poshedly, Jim Rouse, Tano Scigliano, John Stauter, Wess Stuckey, Harry Taylor, Gary Thompson, Cindy Weaver, Bob Vickers ARTICLE SUBMISSIONS - Article submissions to the EJASA on astronomy and space exploration are most welcome. Please send your on-line articles in ASCII format to Larry Klaes, EJASA Editor, at the following net addresses or the above Society addresses: klaes@verga.enet.dec.com or - ...!decwrl!verga.enet.dec.com!klaes or - klaes%verga.dec@decwrl.enet.dec.com or - klaes%verga.enet.dec.com@uunet.uu.net You may also use the above addresses for EJASA back issue requests, letters to the editor, and ASA membership information. When sending your article submissions, please be certain to include either a network or regular mail address where you can be reached, a telephone number, and a brief biographical sketch. DISCLAIMER - Submissions are welcome for consideration. Articles submitted, unless otherwise stated, become the property of the Astronomical Society of the Atlantic, Inc. Though the articles will not be used for profit, they are subject to editing, abridgment, and other changes. Copying or reprinting of the EJASA, in part or in whole, is encouraged, provided clear attribution is made to the Astronomical Society of the Atlantic, the Electronic Journal, and the author(s). Opinions expressed in the EJASA are those of the authors' and not necessarily those of the ASA. This Journal is Copyright (c) 1992 by the Astronomical Society of the Atlantic, Inc. HISTORY OF THE OHIO SETI PROGRAM by Robert S. Dixon The Ohio SETI (Search for ExtraTerrestrial Intelligence) Program began with a strong impetus from NASA's Project Cyclops. The goal of Cyclops - a paper study conducted in the early 1970s - was to assess what it would take in terms of time, people, equipment, and money to mount a large search for radio signals from interstellar civilizations. The end result was a report which was widely circulated as a NASA Special Publication, recommending a small array of radio telescopes which would grow with time as needed. During my Project Cyclops research, it became clear to me that many theoretical papers were being written about SETI but no one was doing any extensive actual searching. I also realized that we had a large, fully operational radio telescope available at Ohio State University (OSU) which was designed explicitly to search for new radio signals in the sky. It had just completed the largest all-sky survey of natural radio signals made up to that time. Coincidentally, this telescope was also chosen by the Russian scientist Gindilis as the telescope most suited for SETI, due to its unique surveying ability. Although we had no money, we did have a crew of able volunteers on hand. Faced with the alternative of ultimately turning off the telescope and letting it rust away, we decided that we had a respon- sibility to seize the opportunity which had been thrust upon us and start a real SETI program. It did not take too much arguing to convince John Kraus, Director of the OSU Radio Observatory, to allow me to use the telescope for humanity's first full-time SETI program. The Ohio State Radio telescope is larger than three football fields in size and equivalent in sensitivity to a circular dish 52.5 meters (175 feet) in diameter. The beam of the telescope is elliptical, being forty minutes of arc in the declination (vertical) direction and eight minutes of arc in the right ascension (horizon- tal) direction. This may be visualized by comparing it with the size of the Moon, which is a thirty minutes of arc diameter circle in Earth's sky. The telescope surveys the sky by remaining stationary and allowing the rotation of Earth to sweep its beam in a narrow circular path through the sky once each day. After a few days of observation, the beam is moved slightly up or down and the pattern is repeated. It takes several years to thoroughly search the sky. We went on the air in 1973, using an eight-channel receiver system, originally constructed for twenty-one-centimeter (21-cm) hydrogen line observations by Bill Brundage. Bill later went on to become Chief Engineer of the ninety-meter (three hundred foot) radio telescope at Green Bank (NRAO). Later still he was responsible for preparing the Very Large Array (VLA) in New Mexico to receive the faint VOYAGER 2 spacecraft signals during its flyby mission of the planet Neptune in August of 1989. The bandwidths of the channels ranged from ten to fifty kilohertz (kHz), depending on their distance from the center frequency. The output of the eight channels was plotted as wiggly lines on pen recorders. The charts were laboriously searched for unusual signals by graduate student Dennis Cole - now a contractor to the Jet Propul- sion Laboratory (JPL) - and used as the subject for his master's thesis in Electrical Engineering. This may have been the first graduate degree ever awarded in SETI. The search strategy chosen at the time was to explore in the vicinity of the 21-cm hydrogen line, Doppler correlated to the Galactic Standard of Rest. Due to the random motions of the stars and the rotation of our Milky Way galaxy, signals transmitted at the hydrogen line frequency (1420.4056 megahertz, or mHz) would be received at somewhat different frequencies because of the Doppler shift. To avoid this frequency ambiguity, we made the deliberate assumption that any civilization transmitting at the hydrogen line would offset their transmission frequency in just the right way to remove all their motions with respect to the center of the galaxy, which is the only unique reference point shared by all the galactic inhabitants. It was then up to us to offset our receiver frequency to compensate for Earth's motions to arrive at this unique "galactic" frequency. Because of our uncertainty about the galactic rotation velocity (we measure it by observing the motions of the stars and gas in our stellar neighborhood), we still had to search a total bandwidth of several hundred kHz. A lot of chart paper was generated during the two years this effort continued, but no recognized signals of intelligent origin were found. By 1975, a fifty-channel filter bank receiver had been borrowed from Green Bank. Software for the already old IBM 1130 computer had been developed by Professor Jerry Ehman - now Chairman of the Mathematics Department at Franklin University - and me, to process all fifty channels continuously. The software was sophisticated, with many internal checks for false alarms and equipment malfunctions. Each of the fifty channels was processed independently, and the computer automatically removed the individual gain and baseline variations of each channel. A number of search algorithms were run simultaneously, including searches for both isolated pulses and continuous signals which rose and fell in intensity in just the predicted way (for a continuous, narrowband signal) as they passed through the antenna beams. The highly processed output data were printed every ten seconds for all fifty channels. Signals the computer thought were "interesting" were also flagged and saved on punched cards for later analysis. The IBM computer was built like a battleship and ran without fail for many years. Its operating system could run huge programs in a tiny memory very efficiently. It was fast, even by today's standards. Over the years, a few cold hydrogen clouds were found and huge piles of computer printouts accumulated. There was no magnetic tape drive or equivalent device available, so there was no way to record all the data permanently in computer-readable form. Only the small fraction of data represented by the "interesting" signals were preserved in computer-readable form. Along the way, a small NASA grant was received, which continues today. Two types of unexplained signals were detected during this search. The first kind is quite rare, with the best example being the "Wow!" signal found in 1977. This name was unintentionally applied from Jerry Ehman's comments in the margin of the computer printout when he noticed the signal. The signal was unmistakably strong and had all the characteristics of an extraterrestrial signal. It was narrowband and matched the antenna pattern exactly, indicating it had to be at least at lunar distance. A signal from a nearer object would show a wider pattern. However, the strange signal was not coming from the direction of the Moon or any planet, or even any particular known star or galaxy. Of course there are always many distant stars and galaxies in the beam of a radio telescope all the time, but that is not significant. A check of artificial satellite data showed that no publicly-known Earth satellites were anywhere near the position of the signal source. Furthermore, the frequency of the signal was near the 1420 mHz hydrogen line, where all radio transmissions are prohibited everywhere on and off Earth by international agreement. We searched in the direction of the "Wow!" signal hundreds of times after its discovery and over a very wide frequency range. We never found the signal again. It was gone. In fact, while we were receiving this signal the first time, it turned off as we listened. The radio telescope actually receives two beams from the sky at once (somewhat offset in direction from each other) and subtracts one from the other to cancel out terrestrial radio inter- ference. Objects in the sky are usually received twice with a slight delay, once in each beam. But the "Wow!" signal was received only once, indicating either that it turned off after the first beam received it, or that it turned on after the first beam had passed it. What was the "Wow!" signal? Probably we will never know. Conceivably it could have been a secret military satellite in solar orbit, transmitting on an illegal frequency. Military transmitters often ignore civilian agreements. Its characteristics rule out any terrestrial transmitter, near-Earth satellite, reflection from space debris, or equipment malfunction. Perhaps it was a transmission from some other civilization. If so, it seems that they were not trying very hard to attract our attention, since the signal disappeared before we could really find out what it was. The other kind of unexplained signals we receive are much more numerous. These are narrowband pulses (lasting less than ten seconds) which go "bump!" in the night. There have been thousands of such signals received, apparently from all over the sky, and never from exactly the same direction more than once. Clearly these signals are not from any single source (intelligent or otherwise), but they are very interesting in their own right. They could be some form of previously unknown astrophysical phenomenon. As an example, pulsars were first thought to be of alien origin when discovered in 1967, due to their regularly timed radio waves. They are now known to be rapidly rotating neutron stars, the remains of supernovae. Of course pulsed signals like these could easily be caused by terrestrial radio interference or equipment malfunction. But if those were their sources, then they should appear randomly scattered across the sky. The interesting thing is that they do not. They exhibit a zone of avoidance along the galactic plane and areas of concentration above and below the galactic center, along the galactic north and south polar axes. It is possible that the zones of avoidance and concentration are caused in some complex unknown way by an interaction between the galactic continuum radiation and the automatic gain and baseline correction algorithms in the computer. We simply do not know. A resurvey of a portion of the same area shows roughly the same effect, so the phenomenon appears to be repeatable. We plan to resurvey this area again with all new equipment in the future. At one point, there was danger that the telescope would be destroyed. The land under and around the telescope was sold without our knowledge to a developer who wanted to enlarge the neighboring golf course. The developer wanted the telescope torn down and completely removed. This created a furor that was widely reported in the world press. After great struggle and with help from many people, the telescope was saved and a long-term lease was signed for the land. For several years we published the first and only SETI magazine, called COSMIC SEARCH. Its editorial board included all the worldwide luminaries of SETI. The magazine was a technical and popular success, receiving great praise on all fronts. Sadly, it was a financial failure and finally folded after the thirteenth issue. In the middle 1980s, a new and more powerful computer was donated by Digital Equipment Corporation. We began what we knew would be years of effort to place it into operation in the next generation of the Ohio SETI Program. Unfortunately, while this development was proceeding, the old IBM computer came to a premature death at the hands of a mouse. The mouse had built a nest at the air intake to the disk drive, cutting off the machine's air supply. This caused the disk drive to destroy itself. IBM said the computer was so old that it would cost a lot of money to fix it. They also would not guarantee it to work normally even after it was fixed. So regretfully we abandoned the IBM computer and devoted all our efforts toward getting the new Digital computer operational. During the years of eight-channel and fifty-channel observations, we accumulated more on-the-air SETI observing time than all earlier or contemporary SETI programs combined. The new system (now in test operation) has many improvements over the earlier one. No assumption as to exact signal frequency is made, as the entire "water hole" (1.4 to 1.7 gigahertz, or gHz) is searched continuously in three thousand channels. When a signal is found the search is temporarily suspended, so that the signal may be examined immediately in great detail and studied for an hour or so. We call this the SETI ZOOM system, because of the way it seizes upon any detected signal and focuses in on it. This systems avoids the problem encountered by other SETI programs where interesting signals are found after-the-fact as part of a systematic search, but are no longer there when further observations are attempted. Russ Childers has now written his masters thesis on this system. An online catalog of known Radio Frequency Interference sources has been developed, to be used by the computer to ignore them. A new type of radio telescope is being designed and a small prototype has been successfully tested. This telescope is called a Radio Camera, since it forms an image of the entire sky at once. This avoids the possibility that a signal might arrive from an unexpected direction but be missed by radio telescopes that are looking in "likely" directions. Jim Bolinger wrote his master's thesis describing the prototype. Plans are now being made to build a much larger one. Steve Brown is writing his masters thesis on several aspects of this development. We have named this the Argus telescope, after the being of Greek mythology that had one hundred eyes and could see in all directions at once. It is the physical realization of a concept that has been fictionalized earlier by Carl Sagan in his 1985 book, CONTACT, and by Arthur C. Clarke in his 1976 novel, IMPERIAL EARTH. A new method of detecting unknown signals is being developed, based on the Karhunen-Loeve transform. Unlike the Fourier transform commonly used, this method makes no assumptions as to the type of signal being received. It works well with all types of signals, particularly so with complex ones. Professor Chuck Klein and his students are running computer simulations of the signal detection process, comparing the KLT approach to the FT approach. The Ohio SETI Program has now been merged with the Canadian SETI Program run by Bob Stephens. Bob is now at Ohio State University and we are jointly figuring out how we can best combine our equipment. This was made possible by a large increase in the size of our NASA grant this year. The Flag of Earth flies at the OSU Radio Observatory and many other SETI locations around the world. It symbolizes the fact that SETI is carried out on behalf of Humanity as a whole. The individual people, organizations, and nations involved are but a part of the incredible work being done to find intelligent life in the Universe. Related EJASA Articles - "Does Extraterrestrial Life Exist?", by Angie Feazel - November 1989 "Suggestions for an Intragalactic Information Exchange System", by Lars W. Holm - November 1989 "Radio Astronomy: A Historical Perspective", by David J. Babulski - February 1990 "Getting Started in Amateur Radio Astronomy", by Jeffrey M. Lichtman - February 1990 "A Comparison of Optical and Radio Astronomy", by David J. Babulski - June 1990 "Curbing Light Pollution in Ohio", by Robert Bunge - June 1991 "The Search for Extraterrestrial Intelligence (SETI) in the Optical Spectrum, Parts A-E", by Dr. Stuart A. Kingsley - January 1992 "A History of Ohio's Perkins Observatory", by Earl W. Phillips, Jr. - February 1992 THE HYADES: A STAR CLUSTER RICH IN MYTH AND ASTRONOMY by Ken Poshedly and Don Barry Consider the Hyades in the constellation of Taurus the Bull, an open star cluster considered by most too big to be a telescopic object and not quite bright enough to be a dazzling unaided-eye group from urban skies. Binoculars best reveal this group's beauty, ranging from the distinctly V-shaped bright stars which form the snout of the Bull, Taurus, to the hundreds of dimmer cluster members in the vicinity. The Hyades cover over five degrees of the sky. The total magnitude of the cluster is 0.5, but with its individual stars so thinly distributed, it seems less so. The Hyades have been known variously by the Greeks, Romans, and Arabs as Thyrene (or Thyene or even Thyone), Parilicium, Sidus Hyantis, Al Mijdah, and Al Kilas. From ancient Greece to China, the Hyades were associated with wet and stormy weather due to their seasonal evening appearance in rainy November and disappearance in wet May. In Greek mythology, the Hyades were the seven daughters of Atlas and Aethra, making them half-sisters of the much more famous Pleiades, another star cluster in Taurus. They were given the job of raising the infant Dionysus (Bacchus), son of the god Zeus and Earthly princess Semele. Zeus rewarded them for their good work with a place in the heavens. The classic V-shape outlines the snout and horns of Taurus. The Bull's horns extend all the way to the star El Nath and a corner star in the constellation of Auriga. The Pleiades mark the back of the Bull: Perhaps these stars are stinging the Bull and goading him into confrontation with Orion. Ahead of the V, a thin line of stars mark Orion's shield, well placed to deflect the sharp horns. The middle- left star, Theta 1 and 2, of the V is a lovely visual double, one of the best wide equal pairs in the sky. Today we know the Hyades to be the closest well-defined star cluster to our own solar system. Although the cluster stars are young (under one billion years), the cluster age itself is old compared to many more familiar open clusters, which often disperse within tens of millions of years of formation. The entire group is moving through space relatively slowly - about fifty kilometers (thirty miles) per second - toward a point several degrees east of the red giant star Betelgeuse in Orion. Fifty million years from now, the Hyades and other stars known collectively as the "Taurus Moving Group" will appear as a dim telescopic object less than half of one degree in diameter. The Hyades distance from Earth, so important to our understanding of more distant star clusters, was the subject of former ASA member Edmund Dombrowski's Ph.D. thesis. His determination, based on double-star observations in the Hyades, gives the most precise measurement to date: Some forty-eight parsecs or 157 light years. The age of the Hyades is inferred from the absence of bright, massive stars, which burn up their nuclear fuel very rapidly and meet their calamitous ends. Several very important binary stars with relatively rapid orbital periods are found in the Hyades. These stars are the best source of knowledge about stellar masses and distances in the cluster and have been studied extensively by Georgia State University (GSU) astronomers. The star 51 Tauri was discovered to be a binary by Hal McAlister in the late 1970s. It has an orbital period of 11.295 years. Other notable binaries and their orbital periods are: Finsen 342 (6.277 years), ADS 3475 (16.3 years), ADS 3210 (27.672 years), and ADS 3135 (89.470 years). Of these, only the last is resolvable in an amateur optical instrument. Even then, with maximum separation of 0.57 arc seconds, it is a test of superb optics and atmospheric conditions for twenty-centimeter (eight-inch) and larger telescopes. Historically, the Hyades distance was first determined through what is now called the "moving cluster method". In this technique, which works only for a cluster as close as the Hyades, the motion of the cluster through space is apparent on exposures taken years apart. The direction of each star is plotted, and when viewed as a whole, appears as a series of arrows which meet at some location in the sky toward which the cluster is moving. Only the Hyades are sufficiently close that this motion and "vanishing point" is detectable in exposures taken a few decades apart. A study of the relative velocity of the cluster and the distance of its "vanishing point" gives an estimate of the cluster distance, independent of the properties of the stars themselves. Now, binary star studies can determine the distance to individual systems within the Hyades to greater precision than the moving cluster method, and most recent analyses of the Hyades distance use these techniques. Although observers often assume it to be a member of the cluster, Aldebaran is much closer to us at only seventy light years distance. Its ruddy orange color reveals its low surface temperature: Aldebaran is a red giant star that just happens to be in the way. Every three years, the planet Mars passes close to Aldebaran from Earth's view, inviting comparison between the Red Planet and red "Eye of the Bull". About the Authors - Ken Poshedly was Secretary of the ASA through 1990-1991 and now serves as the Publications Chairman. Ken has restored a Criterion RV-6 Dynascope and is still clawing his way through the various levels of "amateur astronomer" status. Ken is a long-time amateur astronomer and maintains an ongoing interest in astronomical writing and historical astronomy. Ken's interests also include education and Volkswagens. A technical writer by profession, Ken has a degree in Journalism from Kent State University in Ohio. Ken is the author of the following EJASA articles: "Did Kepler Fake the Evidence?" - May 1990 "When the Light Gets in Your Eyes, You Shouldn't Have to Drive to the Country" - February 1991 (with James Smith) "Solar Eclipses in History" - July 1991 "The July 11 Total Solar Eclipse and the ASA" - November 1991 Don Barry, ASA President, is an astronomer with the Center for High Angular Resolution Astronomy (CHARA). Don is currently writing his Ph.D. thesis involving measuring the relative luminosity of very close double stars. Don's professional interests include optical interferometry, binary astrometry and photometry, and innovative instrumentation. An active amateur as well, Don's interests include telescope making, antique instruments, and fostering amateur- professional collaborations. Don is the author of the following EJASA articles: "Astronomy Week in Georgia" - August 1989 "Profiles in Astronomy: Albert Whitford" - September 1989; an interview with Edmund Dombrowski and Sethanne Howard "Alar Toomre: Galactic Spirals, Bridges, and Tails" - October 1989; an interview with Edmund Dombrowski and Sethanne Howard "Observing the Wreaths of Winter" - December 1989 "The Mayall Four-Meter Telescope" - May 1990 "A Southern Travel Diary: An Observer's Tale" - August 1990 "Saturn's Great White Spot" - February 1991 THE ELECTRONIC JOURNAL OF THE ASTRONOMICAL SOCIETY OF THE ATLANTIC June 1992 - Vol. 3, No. 11 Copyright (c) 1992 - ASA