| Advisor Journal |
Solar Observing from Spain
| | Jay Pasachoff | July 12, 2006 |
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| Jay Pasachoff at the Swedish Solar Telescope |
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I am in the third year of a project to study the finest structure detectable at the edge of the sun. These features,known as "spicules," make up the solar chromosphere. They are only about as big as the smallest features readily observable so they are not well understood, in spite of their having been described by name sixty years ago and drawn in the 19th century. New methods of building telescopes and handling data allow finer spatial resolution than ever before, overcoming "seeing" effects caused by the atmosphere, and we were simultaneously using the Swedish Solar Telescope on La Palma, Canary Islands, Spain, arguably the world's best solar telescope, and NASA's Transition Region and Explorer (TRACE) spacecraft.TRACE has pixels (picture elements) only half an arcsec across, half the titular size of spicules, and the Swedish Solar Telescope can even surpass that under the right conditions (though not every day). |
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| The dome of the Spanish 10.4-m telescope, under construction. |
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My work on this joint project is sponsored by a grant from the Solar-Terrestrial Division of NASA and supplemented with Williams College funds. Each year I have brought two students with me to observe with the Swedish Solar Telescope. The students from 2004, David Butts and Joseph Gangestad, both just graduated and are going on in aerospace engineering. The students from 2005 were Owen Westbrook and Jennifer Yee; Owen has a job as a research assistant with Chandra X-ray Observatory Data at the Harvard-Smithsonian Center for Astrophysics after completing a senior thesis with me on these chromospheric studies; Jennifer will be a senior (she is at Swarthmore and worked with me at Williams College as part of our Keck Northeast Astronomy Consortium student exchange, originally funded by the Keck Foundation and now funded by the National Science Foundation). This year I came with Megan Bruck, a senior who is doing a thesis with me, and Anne Jaskot, a junior who just joined one of my colleagues in Tasmania to observe last month's Pluto occultation.The Swedish Solar Telescope has a large flat mirror at the top that reflects light into another mirror and then down an evacuated tube.With the vacuum, there are no air currents from the hot solar radiation to distort the image inside the telescope.An internal lens is 1 meter across, equal in size to the lens of the famous, old Yerkes refractor in Wisconsin near Chicago (which was just sold to a developer who will keep the old astronomical equipment as an amenity), and thus equal to the largest astronomical lens in use. |
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| Williams College students Anne Jaskot '08 and Megan Bruck '07 outside the Swedish Solar Telescope on La Palma, Canary Islands, Spain |
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We observe from a control room in the basement of the observatory. A key part of my observation is the use of SOUP, the Solar Optical Universal Polarimeter, a very narrow band (1/8 Å) tunable filter built and owned by Lockheed Martin Advanced Technology Center and first used on Spacelab on the Space Shuttle some years ago. SOUP has some big pieces of calcite in it; stacking them properly makes the filter so narrow. It is difficult or impossible to get such large pieces of optical-quality calcite anymore, and filters as good as SOUP are rare or nonexistent.Everything is computer controlled and an optical bench of optical parts splits the beam several ways. Splitters in the "red" beam that leads to SOUP feeds three cameras: one for SOUP itself and two others to be used for "phase diversity," which, after detailed and complex data reduction that I don't yet know how to do can lead to superior images with atmospheric effects eliminated. We are taking 1 TB (terabyte) of data a day and we cannot even save all those data, so we have to do preliminary data paring on site.We brought four 300 MB hard drives and one of them is now sitting up at the Observatory while we are in the residential building after dinner; it is undergoing an approximately 10-hour download of today's work.We are being helped on site by staff from the Royal Swedish Academy of Sciences, including long-term staffer Rolf Kever and newer telescope operator Elena and computer programer Roy. |
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| Williams College students Anne Jaskot '08 and Megan Bruck '07 with Prof. Jay Pasachoff next to the entrance flat mirror of the Swedish Solar Telescope on La Palma, Canary Islands, Spain |
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We are hopeful that in the long run we will have high-quality observations of solar chromospheric spicules from which we can make superior measurements of their motions and other statistics.They are known to rise and fall with periods of about 15 minutes.Since they have enough mass to replace the whole corona in less than an hour, it is important to know about how they transfer mass at the edge of the Sun. |
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| Alan Pickwick of Manchester, UK, with his ETX outside the Residencia of the Roque de los Muchachos Observatory, Canary Islands, Spain, at sunset on 11 July 2006 |
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Last week in Durham, New Hampshire, the Solar Physics Division of the American Astronomical Society held its yearly meeting.Among many scientific posters shown was one by Owen Westbrook, Kamen Kozarev '05 (who did a thesis with me on the project the year before), and me. We described some of the reduction of data from the Swedish Solar Telescope and TRACE, and showed some sample images. |
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| Several telescopes at the Roque de los Muchachos Observatory. Left to right on the ridge at top are the 4.2-m U.K. William Herschel Telescope, the Swedish Solar Telescope, and the Dutch Open Telescope. The MAGIC gamma-ray telescope is at lower left and a radio telescope at lower right |
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Just before our observing started, I gave one of two closing talks to the European Association of Astronomy Education summer school that was held this year on La Palma. I talked about our educational work at the International Astronomical Union and about how important middle-school and high-school teachers are to inspire students at ages 13 and 14. I also showed some of our results from the transit of Venus and from the most recent eclipse. One of the teachers, Alan Pickwick from the UK, had a Meade ETX and brought it up to the Observatory last night. We were able to watch it orient itself magically and go right to Jupiter, which showed in the middle of the field of view with its moons.
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| Classifications: Beginning Observing, Astrophotography, Advance Observing, Astronomy Outreach, General, Observatories, Solar| 0/0/0 - 0/0/0 |
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