Live Science
Minor Planet Center

by Steve Nadis

Halley's comet.

For the next month or so, I'll be spending some time at the Minor Planet Center (MPC) and Central Bureau of Astronomical Telegrams (CBAT). Both facilities are based at the Harvard-Smithsonian Center for Astrophysics (CFA) -- one of the world's premier astrophysics complexes, located in a quiet, residential neighborhood of Cambridge, Massachusetts, less than a mile from the heart of the Harvard University campus. The MPC and CBAT are non-profit organizations headed by astronomer Brian Marsden and operated by the Smithsonian Astrophysical Observatory for the 8,000-member International Astronomical Union.

The MPC is about to celebrate its 50th anniversary; it was launched in 1947 at the University of Cincinnati, although its predecessor was based in Germany prior to and during World War II. Brian Marsden took over operations of the center in 1978 when it relocated in Cambridge. CBAT has an even longer history, having been founded by the International Astronomical Union in 1920 in Brussels, one year after the IAU itself was established. From 1922 to 1964, CBAT was based in Copenhagen until it moved to the CFA in 1965. Marsden has been running the place since 1968 during some of the most eventful decades in astronomy.

In a remarkably efficient operation, Marsden and his colleagues -- Gareth Williams, associate director of the MPC, and Dan Green, associate director of CBAT -- collect, review, catalog, and disseminate information about discoveries and follow-up observations of minor planets (otherwise known as asteroids), comets, stellar explosions called "supernovas," and transient phenomena such as violent x-ray emissions and gamma ray bursts. There's no fancy control room comparable to that in the Apollo 13 movie. Marsden, Williams, and Green conduct their business in three ordinary offices, stuffed with the usual stacks of books and papers, and equipped with nothing more dazzling than a computer and modem. Yet somehow they manage to keep on top of this heady flow of information, while publishing daily and monthly circulars (in both electronic and print form) and communicating with hundreds of professional and amateur astronomers throughout the world.

Although the correspondence is often dry -- sometimes consisting of nothing more than the vital statistics of a minor planet or two -- the work is of more than esoteric interest. For keeping track of asteroids and comets in the vicinity of the Earth is the first line of defense against a potential impact which could jeopardize modern civilization and send homo sapiens, like the dinosaurs before them, on a one-way path to extinction.

--Steve Nadis

"What We Need Is A Good Scare"

The British magazine, New Scientist, asked Brian Marsden to review one of the new books about the threat of terrestrial impacts posed by asteroids and comets. He dealt with the matter promptly and efficiently, handing it over to Gareth. There have been 12 books on the subject in the past two years, plus several movies in the works -- including a feature film by Steven Spielberg and the made-for-TV NBC movie, Asteroid, that was broadcast in February. "It's kind of curious," Marsden says. "The search for near-Earth objects (NEOs) has dropped off in the last two years [owing to the termination of the photographic search programs in 1994], during the same time that there's been all this interest, and all these books and movies."

This interest, unfortunately, has not translated into more money for observations -- the amount being spent now, less than $1 million worldwide, is almost certainly less than what will be spent promoting the new Spielberg film. But observations and enhanced sky coverage are what we really need, Marsden insists. "We have to beef up our searches, which are now pretty dismal, so we can find out about these things before we get hit."

The question of how to rally public support for a thorough NEO survey is one Marsden has wrestled with, and fretted over, for a long time. "It takes a dramatic event to get people's attention," he says, "and we thought the comet crash with Jupiter might have done the job." While the event did capture Congress' notice for a while, this attention was shortlived and not followed by an appreciable boost in funding. "It's puzzling," Marsden adds. "With these claims of fossilized life on Mars, which everyone admits is not necessarily the correct interpretation, there's excitement and new space missions planned. Why, with something so speculative, is the U.S. government so anxious to give money, while at the same time we tend to ignore an extraterrestrial hazard that could reduce the planet to rubble?"

Part of the problem, he explains, relates to the weakness of statistical arguments. Even though it can be shown that, over the long run, people are as likely to be killed from an asteroid or comet impact as from a plane crash or other natural disasters, few find those kinds of arguments convincing. Why? Because nobody knows anyone who has died from an impact, whereas we see reports of plane crashes every month. The fact is, we don't have much experience dealing with extremely rare catastrophes that could kill billions of people in a single blow.

Dry, rational arguments on the subject may never succeed in drumming up the political and financial backing needed to sustain a far-reaching NEO search. "What we really need is a good scare," Marsden concludes. Of course, it has to be the right kind of scare -- big enough to shake things up, and make a lasting impression both in our psyches and in the soil, but not so big that we're all wiped out in the process.

Sent By: Steve Nadis on Wednesday, April 9, 1997 at 13:09:52.

30 Minor Planets in 15 Minutes

Gareth Williams is typing away furiously. "When the observations are few and far between, I have some interesting projects to work on," he says, "although I can't say whether anyone else on the planet thinks they're interesting." Today, he's entering the positions of minor planets and comets from the historical literature (mostly from the 1820s to 1930s) into the computer database. He's currently tackling a German journal from 1885. "Since the old observations were generally made with respect to a single comparison star, we can now recalculate the positions of these objects because we have a much better fix on the comparison stars," he says. This information also enables him to improve the orbital estimates for the objects.

It's a long-term project, Williams explains, pointing to the stack of 30 different volumes on his desk that he's slowly going through. He figures he's already entered about 40,000 old observations and has several hundred thousand to go. Ocassionally he gets Harvard students to help with the initial data input. "Of course, they don't have the interest that I do," he says. "For them, it's just typing in random numbers."

I asked him how he maintains his motivation to pursue this huge, and somewhat thankless, task. "It's my job to be interested in these objects," he replies. He also likes "logic problems" -- identifying objects, calculating orbits, and spotting mistakes in the published literature. "It's very satisfying to take a bad observation and make it good." Sometimes he notices that the sign of the declination is wrong, or he sees two numbers that have been accidentally transposed. "Of course, there are limits to what we can do today," he says. "We only make changes that we can be sure of."

While keeping up with new observations is still his top priority, he'll continue to whittle away at the historical data during his spare moments. He can knock off a batch of 30 minor planets in about 15 minutes. After he finishes with the German journals he's working on now, he has some British, French, and American publications ready and waiting. "There's a lot to do and it's going to take many, many years," Williams says. "I hope to see this project through as I plan on being around for quite a while."

Sent By:Steve Nadis on Tuesday, April 8, 1997 at 21:08:01.

The selling of Hale-Bopp

The thing Dan Green was worrying about has started: he's getting flooded with requests for information about Comet Hale-Bopp. Although he's not ready to face the deluge, he realizes some good may come of the inevitable comet mania. Professional astronomers will have their telescopes trained on the object, seeing how much gas and dust are thrown off by the comet's nucleus and hoping to determine the precise mix of atoms and molecules in the "coma" or atmosphere. Green will be one of the astronomers studying Hale-Bopp, following up on a project he's pursued since high school -- trying to correlate the brightness of a comet with its physical characteristics. Amateurs, too, can make critical measurements of the comet's size and brightness, as well as estimates of the size and angle of the tail. With all this attention focused on one "dirty snowball," a lot of useful knowledge may be acquired.

Yet Green is concerned about the hype, the loose talk about Hale-Bopp being "spectacular," and the letdown that is likely to occur. "Hale-Bopp won't be spectacular to the general public," he says. "Scientific American said this is the brightest comet in more than two decades, which is true, but that's not saying much. When I talk about `spectacular,' I'm talking about something as bright as that full moon, and this is much, much, much fainter."

He is particularly irked by a line in Astronomy Magazine asserting that "astronomers call Hale-Bopp the comet of the century." "Which astronomers say that?" he wonders. Hale-Bopp, he concedes, is the comet of the century in only one respect: more people on the planet may have seen it than any other comet in history, simply because it will be visible in the evening sky for several months. Given the hype and the high drama of cult deaths, it has been hard for the general public to ignore this comet and, as a result, millions more than anticipated are likely to see it.

But for his money, Halley's Comet still wins hands down. "Several spacecraft flew by it and we learned more about Halley's than any other comet in history," Green says. There's no doubt in his mind that "Halley's Comet is and was the comet of the century."

Sent By:Steve Nadis on Monday, April 7, 1997 at 12:45:23.

Comet Central: All the News on Streaking Hot Stuff

When I finally track down Dan Green, I realize why it's been so hard for the two of us to get together before: Green is an unusually busy fellow. In addition to running CBAT with Brian Marsden, he edits the International Comet Quarterly, the world's largest journal devoted solely to the observation of comets. He also edits a newsletter for the New England Light Pollution Advisory Group, a volunteer organization which is trying to educate the world about the problems related to light pollution. Meanwhile, he's working towards a PhD in astronomy. As if that weren't enough, he's just put the finishing touches on the newly published Guide to Observing Comets.

Traces of this manuscript -- which he edited and wrote in large measure -- are strewn throughout the office. Green looks a bit tired and admits that completing the book was an ordeal that dragged out over the last two years. He worked on it in bits and pieces, while juggling all his other obligations. The last few months have been a real crunch, as he rushed to get the first edition ready before the hype about Comet Hale-Bopp gets out of control (the comet was discovered while the book was in progress). And of course the "hype" surrounding Hale-Bopp -- thanks to Heaven's Gate -- surpassed his expectations to say the least. Orders are rolling in.

Although the book is not specifically geared to Hale-Bopp, it is intended to be the most comprehensive guide for observing comets ever published. "That's not saying a lot," Green says modestly, "as there isn't much competition." There was one book about observing Halley's Comet -- published by the Jet Propulsion Laboratory and designed for amateur astronomers -- that is long out of print. Other booklets he's seen have been produced for various amateur astronomy groups around the world. The new guide, which should be a valuable tool for both professional and amateur astronomers, provides tips for observing comets in visible, ultraviolet, radio, and infrared wavelengths. "I expect this to be a fluid guide that will be updated every couple of years, owing to the rapid changes in astronomy," Green says. "For example, it's only in the last few years that amateur astronomers have begun using CCDs [charge-coupled devices] to study comets." The CCD chapter will definitely need updating as the technology matures.

The discussion of how to find information about comets on the World Wide Web was also hard to write, he says, as the Web has just taken off in recent years and "everything is changing all the time." New material on these and other subjects will appear in the Guide's second edition, on which Green has already begun work. He's now toiling seven days a week and doesn't expect things to let up anytime soon.

Sent By: Steve Nadis on Friday, April 4, 1997 at 15:52:26.

Minor Planets Numbered: 7300 & Growing

Brian Marsden has just compiled some statistics from the previous month to get a sense of the MPC's capabilities to handle the flood of data that would be pouring in if a Spaceguard-scale survey were in place. Last month, the MPC published 22,000 observations, an average of more than one observation every two minutes. "We're actually getting even more than that because there's quite a few that are not published," he says. Including all the unpublished observations, they receive some 30,000 observations monthly -- or nearly one a minute. "All this is being processed quite readily. It's not not an enormous struggle to keep up with it. Granted, Gareth is here seven days a week, but he does other things too, including all the computer programming for MPC and CBAT."

In his conversations with members of the Spaceguard Foundation, Marsden has heard the MPC would be the logical place to handle data management, at least initially. "Given our experience and track record, it would be kind of silly to start afresh," he says. Yet he acknowledges there are political considerations. "Some European astronomers believe their governments may be reluctant to support their efforts if their work is strictly confined to observation, rather than analysis, as some feel doing observations alone may not require a great deal of thought," he says. "But this is an international venture and it's simply more efficient for some to do the observations, while others handle the calculations." There's little risk, he adds, that bad calculations would go unnoticed for long, "because if we predict an object will be in a certain place at a certain time, and it's not there, then everyone will know we've made a mistake."

With an expanded survey along the lines advocated by the Spaceguard Foundation, the MPC or some other designated "coordination center" could get 10 to 30 observations per minute, or about 10 to 30 times the present rate. Would they be able to keep pace? A faster computer would surely help. In fact, the MPC already has a faster computer, but no one has yet had the time to set it up. Having a computer systems expert on hand would fill one of MPC's greatest voids. Still, Marsden doesn't believe that a massive boost in manpower would be required. They'd hire one person at a time and see how it goes. "Most organizations have too many people," he says. "It's better to have a few people who know what they are doing."

A problem he hasn't yet solved is how to handle observations coming in at the rate of one every couple of seconds, while still finding the time to respond to observers and correct their measurements. "Suppose an observer does something silly, like the other day when someone sent us some measurements that accidently had two decimal points together?" he asks. "Whenever something like that happens, it confuses our computerized system and slows us down. But how much can a program like this guard against the idiocies of observers?" He's confident that the MPC, in a slightly beefed-up form, could handle a greater flow of incoming data. "But we couldn't handle all the questions. People would have to take what we give out without asking a lot of questions."

One strategy would be to insist on a rigid format for all entries; anything deviating from that would automatically be returned. The drawback of that approach, he explains, is that "people don't do what they're told. That's 90 percent of the problem." The result would be that a large number of entries containing errors, or with an improper format, would necessarily fall by the wayside.

Marsden tries to put the issue in historical perspective. Early in the game, when observations of asteroids and comets were few and far between, astronomers had little trouble keeping up with their calculations, even though those calculations were done by hand rather than by computer. Things changed dramatically by the 1930s, as photographic plates became easier to use and calculations began falling behind. The main processing work, at the time, was being done at MPC's predecessor in Germany. "World War II came along and everything collapsed, but it would have collapsed anyway because observations were way ahead of the calculations," he says.

When the MPC resurfaced at the University of Cincinnati in 1947, then director Paul Herget introduced the "modern era" by relying on the rudimentary computers of the day. There were 1,564 known and numbered minor planets in 1947 and 2060 numbered objects in 1978 when Marsden took over operations. Now there are more than 7,300 numbered minor planets. One change instituted by Marsden was to publish the MPC Circulars more often. Monthly publication gave people a bigger, and more frequent, outlet for their work which led to an even greater volume of observations. "At first, that made it tough for us to keep up," he says. "Now we're on top of it again -- at least for the time being. And that's the way it's been over the years -- sometimes observing has been on top, other times computing has been on top." This balance is likely to sway back and forth in the future, as people on the computational end of things try to match their capabilities to the rate of incoming data.

Marsden is still puzzled about one thing, though. Now that MPC Circulars are printed on a monthly basis and electronic notices sent out virtually every day, some observers still want more, insisting that monthly circulars are not enough. "Why are people so impatient for this information?" he asks. "I honestly don't know."

Sent By:Steve Nadis on Tuesday, April 1, 1997 at 16:36:15.

Heaven's Gate: What the Comet Wrought

By the time I reach Marsden, he's already been grilled mercilously by reporters from the Boston Globe, Boston Herald, and other journals who are trying to make some sense out of the carnage in Rancho Sante Fe. But no one -- neither scientists, psychiatrists, nor astrologers -- is likely to produce a logical explanation for the cosmic theories swirling around Comet Hale-Bopp which culminated in mass suicide by members of the Heaven's Gate cult.

Comets always bring out the "lunatic fringe," Marsden says in dismay, pointing to the doomsday predictions and other prophecies that have been tied to comet sightings over the centuries. "It's something we've seen time and time again, although it usually doesn't go so far." In 1973, for example, cultists linked the arrival of Comet Kohoutek with the end of the world. At earlier points in history, comet sightings have been linked to the death of Julius Caesar, Napoleon's invasion of Russia, William the Conqueror's incursion into the British Isles, and the massacre in southeastern Europe led by the Mongol warlord Genghis Khan.

For some reason, Marsden says, there's a tendency to link astronomical phenomena with a whole range of outlandish predictions and beliefs. "We try to educate people, but you can't succeed. Some people aren't prepared to listen, and there's just no reasoning with them."

Whenever a bright comet appears in the skies, a host of crazy theories inevitably emerge. "It's particularly bad when we have a long lead time," Marsden notes. Given that Hale-Bopp was discovered back in July 1995, "there's been a lot of time for all this nonsense to brew and develop." Some people are blaming the San Diego disaster on an image displayed on the Internet showing an object that some inferred to be a "spaceship" lurking behind the comet. Although the object was, in fact, just an ordinary star, the rumors were hard to quell.

"Once people start concocting these far-fetched scenarios, there's no stopping them," Marsden says. "They'll draw on whatever evidence they can -- and conjure up spaceships, if necessary -- to bolster their warped views." The story in this case ended tragically, while providing yet another blow to rational thought. Those whole believe we live in an "age of enlightment," the astronomer adds, are sadly mistaken.

Sent By:Steve Nadis on Friday, March 28, 1997 at 19:39:46.

The Observer & the Observed

Compared to the usual dizzying pace at the MPC, it had been a slow week. Gareth Williams had just three unusual objects to report, as it was the wrong time of month, just past the full moon. "Most people aren't observing right now," he says. Which is fine -- it gives him time to catch up on some of his "rainy day" projects.

At the moment, he's trying to incorporate some ideas from Lowell Observatory astronomer Ted Bowell and the Finnish mathematician Karri Muinonen into his computer program. Bowell and Muinonen have done calculations intended to guide observers to the best time to observe an object. "For example, if you have a small field of view [on your telescope] and the uncertainty in position is too high, your chances of getting the object in your frame are very small," Williams explains. His new program is supposed to tell people when it's most useful to observe and help them figure out what is observable for them, given the capabilities of their equipment. "I've compiled the program and can run it, and it doesn't crash at this point, which is better than what it was doing yesterday," he says.

There are times, he says, when it is "bad" to do an observation. "You can actually make the orbit determination worse. There are other times when you can get a large improvement in the orbit." He's trying to make people aware of that. "The problem comes about because observations have errors in them, even if the observer is extremely careful." An orbit is computed by tracing the path of the object through known positions and then extrapolating the rest. Since the quality of the orbit calculation is dependent on the accuracy of the data, some observations could degrade the orbit, while others could enhance it. "The best time to look is when the uncertainty [in the object's position] is greatest because you can shrink down the `error box' from a huge region of the sky to practically nothing," he says. The new improved orbit calculations contribute to more accurate predictions of the object's position (ephemerides). "People can plug this software into their own PC, which will enable them to figure out the ephemerides for themselves."

Williams is working on several new features designed to make things easier for observers. He's putting in links on the MPC web page, for instance, so that a person can call up information from a previous circular simply by clicking on a reference to that circular. Viewers of the MPC page will be able to move more freely to other pages, where they may find some useful background information. "Some of the stuff in our circulars is pretty esoteric, but most of it is accessible to any reasonably intelligent person," he notes. "We can't dumb it down too much."

Meanwhile, he's also putting orbit diagrams of comets online, so that people can click on that and "get a nice picture of the orbit." The next step will be to post "finder charts" for asteroids and comets. "Most people are too lazy to locate the position from a star chart and who can blame 'em?" he says.

As he talked, my attention wondered to the assortment of cassette tapes on his bookshelf. One in particular, labeled "Laurel & Hardy," lept out at me. Curious, I picked it up and checked out the "liner notes." Evidently the tape contained excerpts from such classics as "Swiss Miss," "Way Out West," and "Them Thar Hills," to mention a few. These zany routines apparently provide a bit of comic relief during the grueling workdays. "I like to listen to music or something funny when I work," Williams explains. "More than 60 years later, Laurel & Hardy are still among the best ever."

Sent By:Steve Nadis on Tuesday, March 25, 1997 at 20:53:22.

Near-Earth Objects: Too Close For Comfort

When Williams turns on his computer in the morning -- generally not too early, as he often works into the wee hours -- he never knows what "goodies" might be waiting for him. Usually, he finds some new minor planet observations sent by the biggest "producers" in the asteroid- watching business: the Spacewatch Telescope in Arizona, the NEAT program in Hawaii, the Xing Long program in China, and the "new kid on the block," ODAS at the Observatoire de la Cote d'Azur in southern France, which just sent its first batch of observations earlier in the week.

This informal network, with the MPC at its hub, is a far cry from the more extensive (and expensive) Spaceguard Survey advocated in a 1992 NASA report. The report called for a coordinated international network consisting of six dedicated telescopes. A 25-year-long survey, the panel of astronomers and planetary scientists concluded, could identify 90 percent of the potentially-threatening "Earth-crossing" asteroids at a total cost of about $300 million.

Earth-crossing asteroids are not just a theoretical possibility, but a reality, though it should be pointed out that just because an object crisscrosses the Earth's orbit doesn't mean it will actually collide with our planet. (The odds of this happening are, fortunately, slim.) Yet calculations performed at the MPC last May revealed that a large asteroid or comet called 1996JA1 came within the moon's distance of the Earth. "That's the biggest object ever to come so close to us," Williams says. "At least that we know about -- there's always that qualification." Indeed, the vast majority of "near-misses" of our planet currently pass by unnoticed.

Despite the very real threat of global catastrophe posed by near-Earth objects (NEOs), neither the U.S. government nor any other country has acted on the NASA recommendation. In an attempt to remedy that oversight, a non-profit Spaceguard Foundation was officially set up in Rome last March by a group of concerned astronomers. (Williams is a founding member and Marsden is on the board of directors.) The principal goal is to initiate a comprehensive surveillance program aimed at answering one question: Is a major asteroid or comet impact due within the next century or two?

In addition to the proposed network of ground-based telescopes, the Foundation also calls for the establishment of a "Coordination Center" where data would be gathered, analyzed, publicized, and archived. Right now, the MPC stands as the logical choice for such a center. "We're the only place on the planet with experience dealing with observers all over the world and calculating the orbits of the objects they find," Williams notes. "Why spend a lot of money setting something else up when we can do it here, with just a little more computational power and another person or two?"

Williams tells me Marsden is, as we speak, readying a Spaceguard Foundation pamphlet for distribution. He's editing the manuscript -- with the uninspired title, "The Spaceguard Foundation" -- when I barge in on him. "Oh yes, the man from Omni...," Marsden says, by way of a greeting. He hands me a copy of the pamphlet which was drafted by Australian astronomer and Foundation vice president Duncan Steel. "We felt we needed some publicity -- a way of trying to promote the whole organization," he explains. The document makes the case that the chance of dying from an asteroid impact exceeds the risk of dying in a plane crash (for the typical resident of America, Europe, or Japan, that is). If the total devastation of a direct hit were averaged out over the years, the "annual expectancy of loss" from an impact would amount to many billions of dollars. By contrast, the amount of money now being spent, worldwide, on observational programs is a paltry sum -- less than $1 million. "It's clearly not enough," Marsden says. "We've got to do better."

The main thrust of the Spaceguard program, he adds, is "to find your enemy before it finds you. If we find no specific danger in the next century, that's fine. We can all sleep better. The dinosaurs, mind you, didn't have this luxury 65 million years ago to go out and look for these things. If they did, they might have found a way to survive."

The top priority should be to boost the observational effort. A NASA scientist once remarked that the number of professional astronomers searching for asteroids and comets, worldwide, is fewer than the number of people working in a single fast-food restaurant. Marsden agrees that the amount of sky being covered now by the major programs -- Spacewatch, NEAT, and ODAS - - is "dismally small." He points to the July 1994 collision between Comet Shoemaker-Levy 9 and Jupiter, which was witnessed throughout the world, as evidence that we can predict these kind of events in advance. "We only had 14 months notice in that case, but ideally we'd like to have decades to try to avert a collision," he says. "We don't have to discover these things when they're right on top of us."

Ironically, Marsden notes, support in this field is currently dwindling. He shows me a brochure describing an International Astronomical Union meeting, sponsored by the United Nations Office on Outer Space Affairs, held in Europe. "The IAU and UN are interested in getting Third World countries involved in the search for asteroids and comets, which is a good thing." But, meanwhile, the Australian program, which has been the most active in the southern hemisphere, is on the verge of running out of money. "I'm all for promoting this work in developing countries. We all have to be involved because this is a global problem. But we can't let developed countries like Australia fall by the wayside," he says, shaking his head in disgust. "It's a strange world we live in." He steps out of the room, for a moment, allowing me time to read the Spaceguard brief and contemplate the end of that world as we know it.

Sent By:Steve Nadis on Thursday, March 20, 1997 at 13:34:10.

Unusual Objects & Feedback Loops

When I arrive on the scene, Gareth Williams is in his usual position, hunched over the computer keyboard. I notice that the pile of soda cans and bottles on the floor behind him is starting to get out control. "I gotta take this stuff home one of these days," Williams says, sheepishly. "Harvard doesn't recycle them, which is kind of a pain."

He's about to send off a Circular to publicize the discovery and recent observations of new "unusual objects." By unusual objects, he generally means comets or asteroids that come close to, and possibly even intersect with, the Earth's orbit around the sun. The Circular lists available observations for each object, the orbital trajectory that was calculated by his computer program, and the "empheris" -- that is, the predicted position of the object in the sky telling observers where to look.

"This is a Discovery Circular that may need to be updated because we've received additional observations," Williams says. "As a result of the last Circular, we've received more observations. This version, hopefully, will have a more precise estimate of the positions and orbits." This kind of positive feedback loop -- in which the announcement of a discovery leads to further observations which provide a more detailed knowledge about a newly-found object -- lies at the heart of MPC's mission.

I follow Williams down the hall, where he asks Marsden to proofread the bulletin before he sends it out by e-mail to hundreds of subscribers. "People get miffed when we get their names spelled wrong, which is why I like to have someone else check it for me," Williams explains.

I stop to ask Marsden about the idea of feedback loops in his work, and he provides a nifty example. "We received some observations from NEAT [Near-Earth Asteroid Tracking]," he says, referring to a project run by astronomers at the Jet Propulsion Laboratory (JPL) in Pasadena which relies on telescopes based on Mauna Kea in Hawaii. "NEAT transmits data from Hawaii to JPL; they analyze the data in the morning and send it to us. We process that in the afternoon and put it on our `confirmation page,' which is our way of soliciting help from other observers. It's now nighttime in Europe, so observers there can get a confirmation and send the measurements back to us by 5:30 E.S.T., before we quit for the day." This example, which is more the rule than the exception, gives a sense of the kind of closeknit asteroid-observing network that Marsden and his colleagues hope to establish.

Sent By:Steve Nadis on Saturday, March 15, 1997 at 20:04:12.

Who Put the Bopp in Hale-Bopp?

The Central Bureau for Astronomical Telegrams is in business to report on observational, as opposed to theoretical, discoveries. Its responsibilities overlap with the Minor Planet Center, as do its personnel and physical space -- with both centers, for the most part, crammed into a few modest-sized offices in Building A of the Center for Astrophysics. The prime emphasis at CBAT is on comets and supernova (exploding stars), which is in itself an exploding industry. The supernova discovered a few months ago, for example, "SN1996bx," was the 76th supernova discovered in 1996, which constitutes a single-year record. Yet Brian Marsden stresses that "the act of discovery, itself, doesn't mean much if you don't follow up on it. The whole point of publishing these things in our telegrams is that someone might follow up on it." The Bureau sends out its telegrams (or Circulars), with announcements of new discoveries, every day or two to more than 400 print subscribers and 500 e-mail subscribers as a way of keeping people in the observing community apprised of new developments.

"Until a few years ago, when somebody reported a probable supernova, we sent out word in our notices and there was often no feedback on it," Marsden says. These days, there is more follow-through, but that involves having people do more work, which does not always pay off. Last night, for instance, an amateur claimed to have found a new supernova -- a fact that was reportedly confirmed by a professional astronomer. "I passed the information on to one team who checked it out and determined that it was an ordinary star, not a supernova," Marsden says. "They were annoyed and have every right to be. With telescope time at a premium, and astronomer's time at a premium, you can't afford too many false alarms." He and his colleagues are now considering more rigorous conditions that have to be met in order for alleged supernova discoveries to be taken seriously.

One of CBAT's important roles is in determining what is a discovery and in giving credit where credit's due. "We've run into trouble from some professional groups regarding the definition of a 'discovery,'" Marsden says. "If a team of four people discovers a comet, is everyone on the team a discoverer? And what about people who do the follow-up observations, if the original observers don't do it themselves?"

As examples, he cites the original announcements about Comet Hale-Bopp and Comet Hyakutake which came through CBAT, captured a lot of media attention, and "brought a fair amount of fame to the discoverers." Comet Hale-Bopp -- a bright comet that should be visible to the naked eye right now -- was discovered in July 1995 by Alan Hale, an active comet-watcher from New Mexico, and Thomas Bopp, an amateur astronomer from Phoenix, Arizona. Hale's name appears first owing to the judgment of Marsden and his colleagues that Hale found the object about 15 minutes before Bopp did. Comet Hyakutake, which was visible in the spring of 1996, was a less controversial call, named after its sole discoverer, a Japanese amateur named Yuji Hyakutake.

Shortly after his comet find, Hyakutake was brought to the Adler Planetarium in Chicago where he was wined and dined. Some comet hunters of the previous century received even more handsome rewards. Maria Mitchell of Nantucket, for instance, was given a gold medal from the King of Denmark for spotting a comet in October, 1847. A few decades later, the comet-hunting activities of Louis Swift, the co-discover of Comet Swift-Tuttle, were supported by a wealthy New York industrialist who provided Swift and others with a payment of $200 for every new comet discovered. E.E. Barnard, a well-known American astronomer from Nashville received 10 of these awards and used the money to purchase a piece of real estate he called "Comet House." Things are a lot different nowadays, Marsden comments. "Most people get a piece of paper for their trouble, and that's about it."

Marsden is not prepared to remedy this situation by offering any cash rewards himself, but he feels strongly that the process of naming comets, and giving proper credit. should be done on the basis of fairness and simplicity. He takes this job seriously, although perhaps not with the single-minded devotion of the French astronomer Charles Messier, who elevated comet-hunting to a fine art in the 18th century and reportedly was sadder when he missed a comet sighting than when his wife died.

Sent By:Steve Nadis on Tuesday, March 11, 1997 at 12:23:19.

A Cautionary Tale

Sitting in his office just a few doors down the hall from Gareth Williams, Brian Marsden -- at 59, the veteran asteroid and comet-tracker of the bunch -- relates a "cautionary tale" that shows how things, on rare occasions, can go very, very wrong. He is a jovial man who enjoys a hearty laugh and can spin a good yarn, in a voice worthy of a stage actor -- or a sea captain. About a year ago, he tells me, an amateur astronomer in England thought he had found a minor planet using a charge-coupled device (CCD) detector -- a device that basically counts light photons. "The observations were just for one night and they were three weeks old, so there was not much we could do about it. "Gareth made the mistake of telling the guy we'd file his observations, which meant putting it in a place that was one step from the trashbin," Marsden says. "The fellow misunderstood. He talked to the press and told them he had discovered a new minor planet. Somehow, the word `minor' got dropped, and a new planet near Mars was reported in the British press on TV and radio and in the papers. It was ridiculous!"

Meanwhile, he notes, other amateur astronomers who'd been making significant contributions in total obscurity were annoyed by all the exposure this "rank amateur" had received. "That shows how things can backfire and how careful you have to be in explaining something to the would-be discoverer." A new policy emerged as a result of the debacle, one that sounds as if it might have originated in the Pentagon press office rather than from the astronomer Marsden's lips: "Don't give out any more information than you have to."

Sent By:Steve Nadis on Wednesday, March 5, 1997 at 12:23:38.

The Minor Planet Center in Action: The Chain of Command

When I interrupt Gareth Williams, he is analyzing some data that have just arrived, via e-mail, at the MPC. Observations -- which come in at the average rate of about one every two minutes -- can pile up if they're not attended to promptly. "We tend to deal with just numbers, not a lot of pretty pictures," explains Williams -- a 31-year old British astronomer who's been associate director of the MPC for the past seven years. He arrived at the center in January 1990 for a three-month appointment. That was followed by a second three-month appointment. After getting lucky and receiving a "green card" in the lottery, he's been at the MPC ever since.

The center's main job is to gather and distribute information about asteroids and comets, calculate the orbits of these objects, and generally keep track of their peregrinations in the sky. Observations -- hopefully arranged in a standard, numerical format -- are sent to the MPC as the first step in the process. Next, Williams and Marsden check the entry to make sure the objects (asteroids or comets) are correctly identified and that no gross errors have been made. (Only accurate measurements will receive further attention.) If the objects appear to be new, they are assigned temporary designations until they can be confirmed by follow-up observations. When an observer can verify the findings on a second night ("one-night stands don't count with us," Williams says), the object is given a new, provisional designation. In the past two weeks, 1,600 such designations have been awarded.

The entry Williams is currently evaluating was sent by amateur astronomers from the Fort Bend Astronomical Club in Missouri City, Texas. (Asteroid hunting, he notes, is a field where amateurs can make a useful contribution.) The Fort Bend observers are reporting on two presumably new objects that they call FBAC13 and FBAC14. Williams acknowledges receipt of their missive and then lets his computer go to work. Using a program that he wrote, he checks to see if the objects correlate with others previously identified. It turns out that both of these objects are identical to objects discovered last month by the Spacewatch Telescope team at the Kitt Peak Observatory in Arizona, he learns. The Spacewatch discoveries are so new that they haven't been published. "The Fort Bend people are not going to be happy about this," he says.

Williams then sends a message back to the Texans telling them that the things they thought were new were, in fact, known objects. Both are so-called "main belt asteroids" -- part of a vast reservoir of orbital rubble residing in the gap between Mars and Jupiter. The original note from Texas came in at 11:06 a.m., and Williams is sending his response with the previously-assigned designations of the objects at 11:29. "That was slow because I was explaining things to you as I did them," he tells me." Normally, it can be a quick turnaround of just a few minutes.

"It's often an impersonal process," he adds. "There are people I've had e-mail communications with for years and years -- like Dave Balin of the Dominion Observatory in British Columbia -- but never met in person or even talked to over the phone." By and large, that's not a bad thing. "We tend to discourage phone calls, as they can be really disruptive," he says. "Most people come around to realizing they have to do things our way" -- sending notes in a standard format, citing a tentative name for the object, the time of the observation, the object's position in the sky, its brightness, and the observatory code. "They can't all be Frank Sinatra."

There are, of course, the occasional nuisance calls (or letters or e-mail messages) from cranks. A woman named Nancy, for instance, has been going around claiming that Comet Hale-Bopp is the 13th planet; it's going to hit the Earth; and there's been a massive conspiracy to suppress this information -- knowledge she gained, evidently, by channeling aliens. "She's commented on me personally, casting aspersions on my character," Will iams says. "That's libel. But if I were to pursue any legal recourse, it would be a case of science versus pseudoscience, and there's no guarantee a jury would come down on the side of science."

Fortunately, most of his interactions are much more straightforward. He might inform observers of the new provisional designations for their object, tell them the number of the known object that their alleged discovery matches, or say that their measurement is 'bad.' "They usually don't take the bad news personally," he says, "but we've never lost an argument like that." Williams realizes he is not a kingmaker, capable of making or breaking so meone else's career. "This may not be a position of power, but it is a position of responsibility," he notes. And he takes that responsibility seriously, often working seven days a week just to prove the point.

Sent By:Steve Nadis on Monday, March 2, 1997 at 12:31:31.

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