Amateur astrophysics in the Arctic Circle.
The Arctic Circle, at approximately latitude 66[degrees] 30' north, is considered by many to be the southern limit of the Arctic region. The name Arctic is derived from the Greek word arktos, meaning "bear." This is in reference to the constellation Ursa Major, or the Great Bear, which is prominent in the northern circumpolar sky.
The northern third of Finland lies within the Arctic Circle. Here, part of winter is a period known as polar night, when the Sun doesn't rise above the horizon at all. In the northernmost extremity of the country, polar night lasts for 51 days; in southern Finland, the shortest day is about six hours long.
Because of this northerly location, weather conditions in the country are usually quite poor. November to January is the worst period--sometimes a month passes without a single clear night! Winter nights here are long and extremely cold (temperatures as low as -30[degrees] Celsius, or -22[degrees] Fahrenheit, are not rare), and the nearly constant displays of the aurora borealis, or northern lights, can be a nuisance to deep-sky observing. Yet despite these adversities, there are many active amateur astronomers in Finland. We have more than 30 astronomy clubs here, with over 10,000 registered members. There are also more than 20 amateur observatories across the country, but they usually have very modest equipment--15-centimeter (6-inch) refractors and 20-cm reflectors are the most common telescopes.
One of Finland's most active astronomy clubs is the Astronomical Association Jyvaskylan Sirius, or Sirius for short. Based in the city of Jyvaskyla, about 240 kilometers (150 miles) north-northeast of the capital city of Helsinki and 480 km below the Arctic Circle, Sirius was founded in 1959 and currently has more than 200 members. Our club publishes a quarterly newsletter, Valkoinen kaapio (White Dwarf), and holds monthly meetings with lectures, weekly telescope-making classes, and regular public star parties and member observing sessions at our two private observatories in Jyvaskyla and Nyrola.
Sirius has owned and operated the facility in Jyvaskyla since 1963. It features a 15-cm achromatic refractor made by the famous Finnish optician and asteroid discoverer, Yrjo Vaisala. This site is now plagued with light pollution, but it's still used for public events.
In 1997 our members built a new facility in the small rural village of Nyrola, about 20 km northeast of Jyvaskyla. Taking advantage of the site's dark, pristine skies, Nyrola Observatory was at first equipped with a homemade 45-cm Dobsonian reflector for visual observing, but two years later we upgraded it to a 40-cm Meade LX200 Schmidt-Cassegrain telescope. We can control the LX200 with its keypad or remotely from a heated computer room adjacent to the observatory building. In the beginning our sole CCD camera was a Santa Barbara Instrument Group ST-7E; now we also use an ST-8E loaned by the American Association of Variable Star Observers (AAVSO).
Initially we used our telescope setup mainly to take tricolor CCD images of deep-sky objects (see some examples on pages 71 and 72). Shortly afterward we started thinking of using it to perform scientifically useful observations as well. Our first serious research project was to hunt for Main Belt asteroids. This was inspired by an article written by Sky & Telescope senior editor Dennis di Cicco in CCD Astronomy. He uses a similar setup and has found more than 100 new asteroids from his backyard in the suburbs of Boston, Massachusetts.
We found our first two possible new asteroids on the very first night of the search, but as the following nights were cloudy, both were lost and never seen again. Then, on November 14, 1999, we found another unidentified moving object on our CCD images. As we managed to recover it the following night too, our discovery was officially confirmed by the International Astronomical Union's Minor Planet Center. The new asteroid, designated 1999 V[O.sub.24], was the first ever discovered by Finnish amateurs. Last year it was given the permanent catalog number 22978, and we named it Nyrola in honor of our new observatory.
Our next project was to conduct photometric observations of cataclysmic variable stars using standard Johnson-Cousins filters in the B (blue), V ("visual" yellow), and R (red) bands. Cataclysmic variables are close binary systems that erupt in brightness more or less unpredictably in response to an explosive event. They include novae, dwarf novae, recurrent novae, symbiotic stars, and others. The explosion occurs when a stream of gas from a fairly normal, cool, low-mass star spills onto an accretion disk surrounding the star's white-dwarf companion. As the gas in the disk slowly spirals down to the white dwarf, instabilities in the disk can cause it to collapse suddenly, producing dwarf-nova flare-ups; the thermonuclear ignition of hydrogen that has piled up on the white dwarf's surface leads to the outbursts of novae and recurrent novae (S&T: October 1998, page 77).
In January 2000 the dwarf nova IY Ursae Majoris discovered by Japanese amateur astronomer Kesao Takamizawa two years earlier underwent an outburst. Kyoto University astronomers belonging to VSNET, the Variable Star Network (http://vsnet.kusastro.kyoto-u.ac.jp/vsnet/), immediately launched an observing campaign, urging observers to closely monitor the star's behavior. Our members volunteered, and we quickly learned the art of doing high-precision, time-series CCD photometry as well as reducing and analyzing our data using the IRAF program. Our first observing runs were very short, obtaining just a few data points for the star's light curve. But soon our sessions became hours long, and we precisely measured the star's magnitude hundreds of times each night. This international collaboration resulted in a technical paper, "Discovery of a New Deeply Eclipsing SU UMa-Type Dwarf Nova, IY UMa (=TmzV 85)," published in the April 2000 Publications of the Astronomical Society of Japan. It was our first coauthored paper to appear in a professional journal.
Our next target was the X-ray nova XTE J1118+480, now known as KV Ursae Majoris. In 2000 we performed high-speed photometry with the SBIG ST-7E camera to help scientists around the world better understand the nova's observed flickering. Our contributions were especially valuable since they complemented simultaneous observing runs with the orbiting Rossi X-ray Timing Explorer and ASCA satellites. Several technical papers will be coming out shortly regarding this galactic black-hole candidate.
We've participated in many observing campaigns of cataclysmic variables in past years, led by the AAVSO, the VSNET, and the Center for Backyard Astrophysics (http://cba.phys.columbia.edu/). One of our most notable campaigns is the very intensive observation of WZ Sagittae, which went into superoutburst in 2001 after 23 years of quiescence. We measured the brightness of this very interesting dwarf nova more than 8,500 times from July to October that year. After the data had been analyzed, I was made one of the coauthors of papers published in Astronomy and Astrophysics and Publications of the Astronomical Society of the Pacific.
Some of our most distant photometric targets are blazars--active galactic nuclei that are thought to harbor supermassive black holes in their centers. The blazars' brightness varies in both short and long time scales. Nyrola is one of the few amateur observatories participating in an international collaboration called the Whole Earth Blazar Telescope (www .to.astro.it/blazars/webt). We monitor a number of blazars in the V and R bands each clear night throughout the year, including BL Lacertae, Markarian 421, S5 0716+714, AO 0235+164, and PKS 2005-489, and report our magnitude measurements to astronomers at Finland's Turku University.
From GRBs to an Extrasolar Planet
Some of the most mysterious and, by far, the most powerful events in our universe are gamma-ray bursts, or GRBs. Going off roughly once per day, these intense flares of gamma radiation typically can attain luminosities up to 3 billion times that of the entire Milky Way galaxy. Current theories suggest that they are produced when the core of a supermassive star collapses into a rapidly spinning black hole, or when a neutron star merges with another neutron star or a black hole. However, since GRBs last only briefly (from a fraction of a second to a few minutes) and occur at random points on the sky, finding the sources' exact locations is a big challenge. That's why catching the extremely faint and short-lived optical (visiblelight) afterglows left by a few GRBs hours or days after the burst is important in determining not only the GRBs' precise positions but also their incredible luminosities and vast, cosmological distances.
In 1999 we joined the GRB Coordinates Network (GCN), operated by NASA's Goddard Space Flight Center in Greenbelt, Maryland (see http://gcn.gsfc.nasa.gov/). After several unsuccessful attempts, on September 26, 2000, we finally managed to catch the 20th-magnitude optical afterglow from GRB 000926--the first by a European amateur group (S&T: January 2001, page 92).
Since then we've tried to observe six more outbursts--GRB 010119, 010324, 010412, 020322, 020409, and 020411, but without success. Their optical afterglows were just too dim for our LX200 telescope. But our February 22, 2001, observation did bag our second afterglow, from GRB 010222. We observed it the entire night using photometric B, V, and R filters--the first such multicolor observation by amateurs. The afterglow's fading was well defined in the resulting light curve (see the diagram above).
Interestingly, even though our other attempts to observe GRB afterglows had negative results, researchers still considered them important since they set an upper limit to ground-based optical observations. That's why our negative observation of GRB 010119 was included in a paper published in the March 1, 2002, Astrophysical Journal.
We get instantaneous GRB alerts from the GCN and AAVSO on our mobile phones, e-mail, and pagers. This way, we receive notification immediately after an outburst has been detected by the Interplanetary Network and the orbiting Rossi XTE, BeppoSax, and HETE-2 satellites.
On September 16, 2000, we performed the ultimate test of our observing accuracy by detecting the transit of an extrasolar planet more than 150 light-years away. The unnamed Jupiter-like object passed in front of the 7.6-magnitude star HD 209458 in Pegasus, causing it to dim ever so slightly for nearly three hours. We took almost 900 CCD images and carefully processed and measured them with IRAF. After averaging several data points, we obtained a beautiful light curve that shows not only the star's brightness drop of 0.02 magnitude but also the expected gradual dimming and brightening between the first and second contacts (see the diagram on the facing page). Astronomer Geoffrey Marcy (University of California, Berkeley) confirmed our observation and told us that we are the first amateur group to succeed in observing such a transit.
We're also actively observing comets, both for our own pleasure and as part of NASA's Small Telescope Science Program (http://deepimpact.umd.edu/stsp/). Our first STSP observing campaign was to monitor the short-period comet Tempel 1, which is the target of NASA's Deep Impact Mission in July 2005. The goal of this program is to gather amateur optical observations of the comet to supplement professional data obtained by the mission's science team. The team uses these observations to determine the comet's properties, such as the rotation period and dust-production rate of its nucleus. These are essential for accurately modeling the comet's environment and refining its orbit, as well as for designing the Deep Impact spacecraft itself and its instruments. We observed Tempel 1 throughout the summer of 2000 with standard photometric filters. The program resumes in 2004, when the comet returns to the inner solar system.
Nyrola Observatory is also participating in the Triton Watch Project (www .boulder.swri.edu/TritonWatch). Based at the Southwest Research Institute in Boulder, Colorado, the project aims to provide worldwide, comprehensive photometric observations of the Neptune-Triton system. The data are analyzed in near-real time to monitor any changes in the planetary system, so a more intensive follow-up study can be conducted. An observing campaign was held in 2001; the next one is scheduled for 2003.
The key to success in amateur scientific work is the ability to be flexible when selecting new targets every night, and even during the course of a night. By closely following the various Internet mailing lists and Web sites, we amateurs can access the very same information as the professional astronomers. International collaboration allows selected targets to be followed nearly continuously around the world in real time. This is especially important when observing outbursts of cataclysmic variables.
Our next major project is to build a radio telescope at Nyrola. It will consist of a 3-meter parabolic dish on a computerized altazimuth mount, with full remote access over the Internet. We plan to operate the telescope at a frequency band of 1 to 10 gigahertz. It's scheduled to be operational in 2003.
For more information contact Jyvaskylan Sirius at Sepankeskus, Kyllikinkatu 1, FIN-40100 Jyvaskyla, Finland, http:// nyrola.jklsirius.fi/, or contact me at arto .email@example.com; +358-40-565-9438.
ARTO OKSANEN is the president of Jyvaskylan Sirius. An Internet consultant by day, he lives in Muurame, Finland, with his wife, Minna, and one-year-old son, Atte.
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|Title Annotation:||astronomy club in Scandinavia|
|Publication:||Sky & Telescope|
|Date:||Nov 1, 2002|
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