"We are a weird bunch," Columbia astronomer Joseph Patterson confessed in a recent newsletter decorated with the logo of a sunlight-hating lizard. In another, he applauded the group's "air of darkness, subversiveness, (and) lack of sanction from the folks that run the world."
They may talk underground talk, but their walk is completely beyond reproach. The lovers of darkness are astronomers, a group called the Center for Backyard Astrophysics and headed by Professor Patterson. These astronomical irregulars are dedicated amateurs, night owls who power up their backyard telescopes, cameras and computers after the sun goes down to record the doings of stars dozens of light-years distant.
Scattered around the globe, the network of more than 30 stargazers in 11 countries on six continents communicates by e-mail and Professor Patterson's newsletter. Their targets, binary stars whose brightness rises and falls over hours or days, are difficult to observe from fixed observatories because the earth's rotation snatches them from view after only a few hours. They supply data to Professor Patterson that he would otherwise be unable to obtain: Having observers in different places on the globe allows almost continuous monitoring of binary stars and also helps counter the effects of bad weather.
In their daylight existences, most are engineers, academics or other technical professionals. Some contribute scientific observations; others learn from the network's reports.
"It's not exactly your average junior high school student with a telescope he got for Christmas, or your frenetic Wall Street type who needs to calm down by watching the stars," Professor Patterson said. "But the equipment is getting cheaper and easier to use. If people stay with this a few years, they can do it."
Participation in CBA is highly satisfying for the amateurs, said Tonny Vanmunster of Landen, Belgium, a 1996 CBA recruit who is chief software engineer for a Belgian noise abatement engineering firm.
"Joe not only selects and promotes the target objects, but he also collects and analyzes all the observations he receives," Vanmunster said. "The immediate feedback on the observational material that we submit, as amateur astronomers, is enormously rewarding."
The far-flung astronomers may be "weird," but they are also technically sophisticated. Some use optical telescopes with mirrors as large as 24 inches for their observations. Images are captured with cameras that use a charge-coupled device (CCD), a computer chip that records photons of light. The CCD cameras, which cost $2,000, are sensitive to very faint light levels and must be cooled to near minus 30o F to minimize "noise" from heat-generated photons.
Using coordinates supplied by Professor Patterson, the amateurs focus on a tiny patch of sky that is expected to yield a variable binary star, then take as many as 300 digital photographs over a five-hour period. Computer analysis of the images can detect the star's rapid changes in brightness and disclose information about how the two stars in a binary system move around each other.
In most binary systems, two stars are locked together with an extremely dense white dwarf star exerting a powerful gravitational pull on a larger star similar to the sun. Hydrogen and other material pulled from the larger star whirls into a gaseous disk that orbits the white dwarf.
With the help of his astronomical irregulars, Professor Patterson has been studying a new class of variable binary stars with short periods, SU Ursae Majoris stars, after the prototype found in the Great Bear, or Big Dipper. In these binary stars, which he affectionately calls "whiz kids," the long axis of the disk's elliptical orbit is itself rotating slowly around the star, a movement called abscital precession. The center's newsletter excitedly reports on "superhumps," periodic disturbances in brightness that correspond to this precessional motion.
A recent binary star that has generated enthusiasm is CR Bootis, two white dwarf stars that orbit one another every 24.5 minutes, by far the shortest period yet observed. Other stars rise in brightness manyfold only every few decades, affording astronomers rare opportunities to observe them; one such star was EG Cancri, which burst into view in late November.
"We're basically using these binary stars, and especially the gaseous disks around the compact star, as celestial mechanics laboratories," Professor Patterson said. "We learn from observation how these disks precess and oscillate, as they are regularly perturbed by the orbiting secondary star."
The center began in 1991 when Dave Skillman of Laurel, Md., a NASA spacecraft engineer, told Professor Patterson that equipment sensitive enough to make meaningful scientific observations was within the price range of most amateurs. Skillman described his robotic observatory, the first built by an amateur that can be left unattended all night. The Columbia researcher needed data from remote locations, and agreed to a collaboration.
A friend of Skillman's in Tucson, David Harvey, was the next to join, and Professor Patterson, armed with a $75,000 equipment grant from Research Corporation of Tucson, continues to recruit amateurs from different longitudes.
"We're strong in North America and Europe, and we have scattered people in places like Israel and South Africa," Professor Patterson said. "But we're weak in Asia. We have coverage in Japan and Australia, but nothing in China, Russia or India."
Professor Patterson has no backyard telescope, but travels to major observatories such as the Cerro Tololo Inter-American Observatory in Chile and the South African Astronomical Observatory near Cape Town, among others, to track his "whiz kids," often rounding out information provided by the amateur network. With observing time at the big telescopes at a premium, he often schedules time at these observatories' smaller telescopes, sensitive enough for his purposes. An assistant, Jonathan Kemp, a 1996 Columbia College graduate and former Rabi Scholar, also makes trips to Chile, South Africa and the Kitt Peak National Observatory in Arizona, and relays his data back to Professor Patterson.
Note to editors: The following members and collaborators of the Center for Backyard Astrophysics (partial list) are available for media interviews.
David Skillman
Center for Backyard Astrophysics (East)
9517 Washington Avenue
Laurel, MD 20723-1868
(301) 490-9593
cba-e@astro.columbia.edu
David Harvey
Center for Backyard Astrophysics (West)
1552 West Chapala Drive
Tucson, AZ 85704-2039
(520) 797-2512
comsoft@primenet.com
Tonny Vanmunster
Center for Backyard Astrophysics (Belgium)
Walhostraat 1A
Landen B-3401 Belgium
32-11-831504
tvanmuns@innet.be
Lasse Jensen
Center for Backyard Astrophysics (Denmark)
Suhrs Alle 5
Farum DK-3520
Denmark
ltj@tt.dk
Robert Fried
Center for Backyard Astrophysics (Braeside)
P. O. Box 906
Flagstaff, AZ 86002-0906
(520) 774-4222
captain@braeside.org
Timothy Abbott
Canada-France-Hawaii Telescope
P.O. Box 1597
Kamuela, HI 96743
(808) 885-7944
tmca@cfht.hawaii.edu
Thomas Augusteijn
European Southern Observatory
Casilla 19001
Santiago 19, Chile
tauguste@eso.org
David Buckley
South African Astronomical Observatory
Post Office Box 9
Observatory 7935
Cape Town, South Africa
dibnob@saao.ac.za
Michael Dusseault
6090 Red Willow Drive
Ottawa, ONT K1C 7J6
Canada
mike@strategis.ic.gc.ca
Gordon Garradd
Post Office Box 157
Tamworth, NSW 2340
Australia
gjg@mpx.com.au
Carole Haswell
University of Sussex
Astronomy Centre
Falmer
Brighton BN1 9QH
United Kingdom
chaswell@star.maps.susx.ac.uk
Coel Hellier
University of Keele
Department of Physics
Keele
Staffordshire ST5 5BG
United Kingdom
ch@astro.keele.ac.uk
Taichi Kato
Kyoto University
Faculty of Science
Department of Astronomy
Kitashirakawa
Sakyo-Ku
Kyoto 606, Japan
tkato@kusastro.kyoto-u.ac.jp
Seiichiro Kiyota
1-401-810 Azuma
Tsukuba
Ibaraki 305, Japan
pfg00474@niftyserve.or.jp
Paddy McGee
University of Australia
Department of Physics and Mathematical Physics
Adelaide, SA 5005
Australia
pmcgee@physics.adelaide.edu.au
Berto Monard
Post Office Box 70284
Die Wilgers 0041
Pretoria, South Africa
lagmonar@csir.co.za
Daisaku Nogami
Kyoto University
Faculty of Science
Department of Astronomy
Kitashirakawa
Sakyo-Ku
Kyoto 606, Japan
nogami@kusastro.kyoto-u.ac.jp
Darragh O'Donoghue
University of Cape Town
Department of Astronomy
Private Bag
Rondebosch 7700
Cape Town, South Africa
dod@uctvax.uct.ac.za
Warren Offutt
Piney Woods Estate
Cloudcroft, NM 88317
offutt@galileo.apo.nmsu.edu
Gary Poyner
67 Ellerton Road
Kingstanding
Birmingham B44 OQE
United Kingdom
gp@star.sr.bham.ac.uk
Alon Retter
Tel Aviv University
Wise Observatory
Ramat Aviv
Tel Aviv 69978, Israel
alon@wise.tau.ac.il
Frederick Ringwald
Penn State University
Department of Astronomy and Astrophysics
525 Davey Laboratory
University Park, PA 16802
(814) 863-1756
ringwald@astro.psu.edu
John Thorstensen
Dartmouth College
Department of Physics and Astronomy
6127 Wilder Laboratory
Hanover, NH 03755-3528
(603) 646-2869
thorsten@dartmouth.edu
Stan Walker
Post Office Box 173
Awanui 0552, New Zealand
astroman@voyager.co.nz
Paul Warhurst
1 / 63 Vauxhall Road
Devonport
North Shore City, New Zealand
pwar022@phy.auckland.ac.nz
Brian Warner
University of Cape Town
Department of Astronomy
Private Bag
Rondebosch 7700
Cape Town, South Africa
warner@physci.uct.ac.za
###