Sun and Snow: Mount Wilson Observatory s Summer Program. By Mike Simmons

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1 Sun and Snow: Mount Wilson Observatory s Summer Program Undergraduate students spend two weeks at this historic mile-high facility, learning about the Sun, the stars, and themselves Ascending the primitive mule trail to Southern California s remote Wilson s Peak in 1903, solar astronomer George Ellery Hale, founding director of Yerkes Observatory, envisioned a professional research observatory at the summit that would lead the world in the New Astronomy astrophysics. With grants from the recently established Carnegie Institution of Washington and other donors, Hale succeeded in establishing this facility, which quickly became renowned for its superbly steady seeing. As home to the 100-inch (2.5-meter) By Mike Simmons Hooker reflector, the world s largest telescope for 31 years, Mount Wilson Observatory dominated modern astronomical research and discovery for much of the 20th century. In addition to Hale, its staff included such luminaries as Edwin Hubble, Milton Humason, Walter Baade, Harlow Shapley, Fritz Zwicky, Allan Sandage, and many others. Despite worsening light pollution from nearby Los Angeles, Mount Wilson has remained scientifically productive. In recent years it has pioneered in the field of laser adaptive optics and has continued its tradition of groundbreaking stellar inter- ferometry as the site of Georgia State University s Center for High Angular Resolution Astronomy (CHARA), which is the world s largest optical interferometric array ( But for the past 13 years Mount Wilson has also hosted a unique educational program that has attracted some of astronomy s future stars, affording them research opportunities not found elsewhere. Each year since 1990 CUREA the Consortium for Undergraduate Research and Education in Astronomy has invited up to eight college juniors and seniors who are considering a career in science or science teaching to work with Mount Wilson s telescopes for two weeks under the tutelage of experienced astronomers. Above: Her face lit by the computer screen, Anne Forbes of Leicester, England, works on her project of taking comparative CCD images of planetary nebulae with Mount Wilson Observatory s 16-inch Meade LX200 telescope. Forbes was a participant in the 13th annual summer program presented by the Consortium for Undergraduate Research and Education in Astronomy (CUREA). This two-week course in astronomy and astrophysics was held last August at the mile-high facility in the San Gabriel Mountains above Los Angeles. In the background is Mount Wilson s 150- foot (45-meter) solar-tower observatory. All photographs in this article are by the author. Sky & Telescope April

2 2002 CUREA student and University of Toronto astrophysics major Helen Kirk adjusts one of the coelostat mirrors that direct the Sun s image into the Snow Horizontal Solar Telescope. This instrument and its associated diffraction-grating spectrograph (located at the bottom of a 15- foot pit) give participants valuable practical experience in solar research. A Hands-On Learning Experience Solar physicist Joseph L. Snider of Ohio s Oberlin College founded CUREA after working for several years with Mount Wilson s historic Snow Horizontal Solar Telescope. This instrument, named in memory of George W. Snow, the father of its donor, Helen E. Snow of Chicago, and designed by master optician George W. Ritchey, was the first permanent telescope at the summit. Installed in 1904, the Snow features a coelostat-fed 24-inch f/30 primary mirror and a subterranean, high-resolution diffraction-grating spectrograph that was added in 1919 and was the first of its kind used for astrophysical research (S&T: February 1991, page 206). The aging telescope was more than adequate for Snider s studies of solar rotation and surface oscillation, the latter being a field of research that began at Mount Wilson. Because the more powerful 60-foot and 150-foot solar-tower telescopes built by Hale alongside the Snow supplanted it for the observatory s regular research programs, the venerable Snow telescope sat idle most of the time. Snider knew that the instrument was still capable of producing excellent results, and its availability presented a unique educational opportunity that this lifelong professor couldn t pass up. Thus, the idea for CUREA was born. Undergraduate physics and astronomy majors rarely get practical experience in astronomical observing and data collection and analysis. Hands-on experience in solar research is even more rare. Snider advertised CUREA at colleges and universities across the United States and brought the best applicants to the mountain for the initial summer session. The wealth of detail revealed by the Snow s spectrograph allowed students under the guidance of Snider and other experienced educators and observers to directly observe and study solar phenomena previously available to them only in textbooks. Solar physics remains an important part of CUREA s curriculum, an approach that promotes Hale s belief that the Sun must be studied in detail in order to better understand other, more distant stars. Still controlled by its original brass paddles and buttons, giant knife switches, DC motors and relays, and a weight-driven clock drive to track the Sun, the Snow lets students experience observing as it was done in Hale s day, before the advent of transistors and computers. The glass photographic plates used by early CUREA students have given way to film, but students still learn various darkroom techniques and develop their own images. Along the way they gain an appreciation for what precision optics and mechanical devices can accomplish without modern electronic accessories. With the Snow telescope students have studied and photographed sunspots, prominences, and the solar spectrum in great detail; measured the solar rotation rate using the Doppler shift of a spectral line at opposite limbs of the Sun; observed hydrogen-alpha and helium emission lines in the chromosphere; looked for the apparent widening or occasional splitting of absorption lines due to intense magnetic fields associated with sunspots (an effect known as Zeeman splitting); watched 5-minute oscillations of the solar surface being displayed in real time on a chart recorder; and much more. Mount Wilson Observatory Association member Dave Jurasevich (far left) introduces CUREA students to the 16-inch LX200 that they will be using for their observing projects. Nighttime Activities Other celestial targets have not been ignored. Students have observed the Moon, planets, variable stars, galaxies, nebulae, and other deep-sky objects with a fine 6- inch Warner & Swasey refractor that was also part of Mount Wilson s early solarresearch program. This telescope has now been replaced with a computer-controlled 16-inch LX200 Schmidt-Cassegrain telescope donated by Meade Instruments. The Mount Wilson Observatory Association (MWOA), the observatory s support 78 April 2003 Sky & Telescope

3 group for public programs, recently purchased a Santa Barbara Instrument Group ST-8E CCD camera for imaging and photometry with the 16-inch. In addition, CUREA owns an Optec photometer and a DayStar hydrogen-alpha filter system, and faculty members often bring instruments from their home institutions for use at Mount Wilson. Students learn how to process CCD images and analyze data obtained with the 16-inch using IRAF and other software. CUREA participants also spend two half nights with Mount Wilson s famous 60-inch reflector. The observing program on the big scope is determined by the students themselves. Some telescope time on the 60-inch is usually devoted to visual observing a rare treat for even professional astronomers and experienced amateurs and instruments brought by the teaching staff may be used to gather data. For example, in 2001 an SBIG spectrograph brought by CUREA director Michael Faison (then with Northwestern University and Adler Planetarium, now at Reed College in Oregon) was installed on the 60-inch so students could obtain the spectra of objects that were beyond the reach of the 16-inch. In 1996 participants even spent two evenings with the 100-inch telescope. While the 24-inch Cole telescope of Mount Wilson s Telescopes in Education (TIE) program has been used in the past for simple imaging, last year saw CUREA utilizing for the first time TIE s new remotely operated 14-inch telescope for student CCD imaging and photometry projects. (For more information about TIE, point your Web browser to Helen Kirk records sunspots at the 60-foot focus of the Snow telescope. The Snow produces a solar image inches across. Daily sunspot recording is carried out at the nearby 150-foot solar-tower observatory, as it has been since Sky & Telescope April

4 CUREA students and staff look on as Georgia State University astronomer Nils Turner (center) explains the operation of the university s Center for High Angular Resolution Astronomy (CHARA) array at Mount Wilson. At upper left is one of CHARA s six 1-meter telescopes designed for stellar interferometry. Mini Projects CUREA s curriculum varies each year, reflecting the program s ability to adapt to the interests of each session s students and the expertise of its staff. I feel that the program s goal all along has been to bring together good teachers and curious students and to follow whatever directions the group finds interesting and valuable, says Snider. CUREA s first week is always a hectic mix of activities. Classroom lectures on solar physics, spectroscopy, optics, and other topics provide the necessary background for upcoming observing sessions. Although some students may have prior experience operating telescopes and instruments, the Snow telescope is generally unlike any they ve used or even seen before coming to Mount Wilson. With beams of intense sunlight passing overhead, observers are literally inside the telescope. Much of the first few days is spent getting acquainted with the Snow and its spectrograph and with the mountain surroundings. MWOA s Bob Eklund traditionally leads an introductory tour of the grounds early in the program, and in the ensuing days there are tours of all of Mount Wilson s facilities. Guest instructors from on and off the mountain also take part. Some report on the research they re conducting, while others work with students on some of the more involved data-analysis problems. The program s second week is devoted mainly to students personal mini projects. Because student backgrounds and interests vary considerably, each project is unique. One student might choose to examine the characteristics of various optical telescope designs, while another might undertake advanced photometric observations of cataclysmic variables. The choice of instruments and how they are used is ultimately made by the observer, and telescope time is allocated according to the needs and merits of the observing proposal, just as with professional astronomers working with larger instruments nearby. The problem was not what to observe, but what not to observe, notes one student. Participants take advantage of opportunities in the sky, too. For example, when asteroid 2002 NY 40 passed within 530,000 kilometers of Earth during last year s CUREA session, Eric Briggs of the Royal Astronomical Society of Canada took time out from his project of measuring the rotation periods of asteroids to record the close encounter. Mini projects don t always end with the expected results, but their real purpose is to teach the various observing methods and techniques. And students are exposed to research at the limit of the resources at their disposal, a situation they re likely to encounter later in their professional careers. It s a practical lesson in science how research is done and what it s really all about. Field trips to other important Southern California facilities, such as Palomar Observatory, Caltech, and NASA s Jet Propulsion Laboratory, round out the very busy final week. CUREA has earned a special place at Mount Wilson, as evidenced by the In addition to hands-on learning, CUREA participants attend classroom lectures given by the teaching staff and guest instructors. While the course is intended primarily for undergraduate physics and astronomy majors, amateur astronomers and other interested adults have often participated in the past and will be considered. 80 April 2003 Sky & Telescope

5 tremendous volunteer effort of its staff and other CUREA supporters. MWOA has been especially supportive, providing scholarships, arranging for volunteer operators for the 16-inch, and making equipment available for use during each session. Individuals who are not officially part of the program give their time as well, including observatory personnel and amateur astronomers who make the drive up the mountain just to assist in the program. An Invitation To date, 81 students from 8 countries have graduated from CUREA. Some are amateur astronomers and public educators who draw on their Mount Wilson experience to better educate others. Two have returned to the mountain to become full-time staff researchers. Perry Rose, a student in the first CUREA class, joined the University of Southern California s helioseismology program at the 60-foot solar-tower observatory. Former student David Hale is now an observer at the University of California s Infrared Spatial Interferometer. Both remain part of CUREA s volunteer corps, giving talks and tours each year. It s no exaggeration for me to say that CUREA changed my life, explains Hale. My participation in the program holds a large proportion of responsibility for where and who I am today. The experience of staying on the mountain for two weeks is something I ll never forget, exclaims Thomas Hakewill, a senior astrophysics student at Cardiff University in Wales, United Kingdom, who attended the 2002 CUREA. I had an amazing time! This year s program will take place August 11th to 23rd. You can apply online at The deadline to submit applications is April 1st. Tuition costs $1,550, which covers all expenses during the session, including meals and shared accommodations at Mount Wilson s Monastery (the visiting astronomers living quarters). For more information contact the 2003 CUREA director, Paula Turner of Kenyon College, at ; turnerp@kenyon.edu. Mike Simmons s previous article, Amid the Treasures of Persia, appeared in the April 2001 issue, page 76. He traveled to Iran in 1999 and 2002 (see his Web site at and attended a conference at Baghdad University in Iraq last January. He s now waiting for an invitation to visit North Korea. Sky & Telescope April