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Clifford G. Toner (1959–2009)

Published onDec 01, 2011
Clifford G. Toner (1959–2009)

Cliff Toner passed away unexpectedly at home in Tucson, Arizona on March 29, 2009. For most of his career, Cliff was involved with the Global Oscillation Network Group (GONG), a facility of the National Solar Observatory in Tucson, Arizona. GONG is a set of instruments around the world to observe the inside of the sun using the sound that is trapped below the solar surface. This science is called helioseismology.

Cliff Toner was born on December 8, 1959 in New Westminster, British Columbia near the western coast of Canada. After receiving his B.Sc. in Physics & Astronomy at the University of British Columbia at Vancouver in 1981, he headed east to the University of Western Ontario in London. His graduate school period was spent in collaboration with David F. Gray, with whom he received both an M.Sc. in Astronomy in 1984, and a Ph.D. in Astronomy in 1988. Toner actually wrote two theses at UWO, one on “Line Asymmetries in F, G, and K Supergiants and Bright Giants” for his M.Sc., and the other on “The Time Variability of Spectral Line Asymmetries and Equivalent Widths for the G8 Dwarf ξ Boo A: Evidence for a Starpatch” for his Ph.D.

After graduate school, Cliff Toner left the cool climate of Canada in 1988 and accepted a postdoctoral position in the warmer temperatures of Hawai’i at the Institute for Astronomy located at the University of Hawai’i in Honolulu. There he worked primarily with Barry LaBonte. At first, he continued his work on ξ Boo A, but he became interested in the sun and helioseismology. This led to the discovery of halos of enhanced high-frequency acoustic power surrounding solar active regions (Ap.J. 415, 847).

At the end of his post-doc, Cliff Toner was hired by the GONG project as a Data Scientist in 1991. He quickly tackled the problem of merging the data from the six GONG sites, which was the major data reduction challenge facing GONG at the time. In parallel, he and Stuart Jefferies developed an algorithm to measure the radii of full-disk solar images to a relative precision of 0.01% by determining the zero points of the Hankel transform of the image. As a by-product of the algorithm, the modulation transfer function (MTF) of each image was also obtained, and this led Toner to develop a merging scheme based on the MTF of every image. It proved to be a very effective approach, and both the radii measurement and the merging algorithm remain in daily use in the GONG processing pipeline. However, there was one remaining challenge to assembling the GONG time series in a seamless manner. Each of the six GONG instruments is slightly and unavoidably misaligned with geographic North, producing an angular misregistration of the solar image between sites. Cliff Toner developed a sophisticated optimization scheme that determined a network-wide solution to the relative orientations of the images, and then pinned down the absolute value with drift scans. He further refined the solutions to compensate for gear irregularities in the camera rotator units at the sites. As a result of these algorithms, Toner was able to co-align all of the GONG images to a precision and accuracy of 0.02°, as verified by his observations of the transits of Mercury and Venus. Without this complex and clever strategy and these extremely important algorithms, it would have been impossible for the GONG data to be merged into a single uniform time series of adequate accuracy for precision helioseismology. Cliff Toner’s tireless, selfless, and generally unseen work behind the scenes was essential for the success of GONG. Toner also developed the scheme for merging together the GONG high-cadence magnetograms, and was working on determining the radii of the forthcoming GONG Hα data at the time of his untimely death.

Cliff Toner was a very tall man, and colleagues at Hawai’i enjoyed the sight of him riding around the campus on a small moped. Everyone who met him loved him for his patience and willingness to help out. One of his colleagues from his stay in Hawai’i, K.D. Leka, recalls that “Cliff was the embodiment of a "gentle giant"; so tall, yet so soft-spoken and patient, and I just recall a sense of his always being ready to help any living thing. Cliff was out with a back injury in March 1991, and it was under his temporarily-abandoned desk that Betsy, the IfA cat had her one (and only) litter (when my cat Audrey, whom many of you know, was born). As the littermates grew, Cliff, Matt Penn and I had kittens crawling over us; I can still hear his chuckles, "well helloooh, who are you there now?" as they would scramble up his chair to his desk. It was always with a smile that he'd greet me when we ran into each other after the "Hawai’i days"; we'd swap some stories, kid updates but only recently we were more in touch as I'm now playing with GONG data. I was heartened to hear he was working on the magnetogram merging, because I knew it'd be done really well with his attention.”

Cliff Toner was a caring and loving person, an excellent scientist, and a hero of GONG. He will be sorely missed by everyone who knew him. He is survived by his wife, Nelsey, children, Ariel, Nathaniel, Miranda, and Kayla, sister Gloria, brothers Ethan (Heather) and Emanuel (Lisa).

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