Thomas Edward Lutz, an internationally-known expert in fundamental calibrations of stellar distances and luminosities, died suddenly, of cardiac arrhythmia, at his home in Pullman, Washington, on February 20, 1995.
Born on November 20, 1940, in Teaneck, New Jersey, Tom was the oldest of four children of Harry and Mary Farrell Lutz. His father was a construction worker, his mother worked for the Veterans Administration. Tom's childhood years were spent in Passaic, New Jersey. When he was 11 the family moved to New City, New York, where he graduated from Clarkstown High School in 1958, winning a New York State Regents Scholarship to attend Manhattan College in New York City. Family finances were tight, so Tom worked as a milkman to help put himself through school. He majored in mechanical engineering, graduating in 1962.
Part way through college, Tom's interests turned toward physics, but he decided not to switch majors because this would have cost him extra time and money he could not afford. His transition to astronomy seems to have involved a certain element of fate. Thinking about going on for a master's degree, Tom happened to read a catalog from the University of Illinois, where his best friend John Healey was considering going. When Tom came across the description of the graduate program in astronomy, he decided to apply. In later years he said that though he had always liked astronomy, he never realized until that moment that it was possible to make a living being an astronomer!
This eventually proved to be true, although Tom did spend his first three summers after graduation working as a mechanical engineer at the U.S. Naval Ordnance Lab in Silver Spring, Maryland. He got his first astronomy job, as a Summer Assistant at Kitt Peak National Observatory, in 1965, the same year he received his master's degree in astronomy.
Tom did very well in the graduate program at Illinois, despite not having had an astronomy course in college. Influences from his graduate school days included Ken Yoss, Stan Wyatt, Ivan King and George Mc Vittie, who was department chair at the time. The year 1965 was of more than academic importance to Tom; that fall he met Julie Haynes, a new astronomy graduate student at Illinois. Tom and Julie were married in July 1966; their daughters Melissa and Clea were born in 1967 and 1969. Tom completed his doctorate in 1969, with Ken Yoss as his thesis adviser.
In his thesis he developed an objective method to measure the Ca II K-line emission widths needed to determine stellar absolute magnitudes by the Wilson-Bappu effect; he used a two-error least squares method to re-calibrate Wilson's K-line absolute magnitudes from trigonometric parallaxes. This led Tom to a lifelong interest in the application of sound statistical methods to the interpretation of parallax observations.
With the exception of several fruitful sabbaticals, the whole of Tom's academic career after getting his Ph.D. was spent at Washington State University, which he joined in the fall of 1969 to teach mathematics and astronomy. He became a full Professor in 1981, and was Director of WSU's Program in Astronomy from 1980 to 1992. He spent two sabbatical years in England, at the Royal Greenwich Observatory in 1976-77 and at University College, London in 1982-83. He spent part of 1986 in Chile as a Visiting Resident Astronomer at Cerro Tololo Inter-American Observatory, and returned there for a full year in 1988-89.
Following his Ph.D. thesis, Tom's research on stellar luminosity calibrations, with WSU statistician Douglas Kelker, led to a 1973 paper which became a landmark in the field. For years it had been partially understood that random observational errors in trigonometric parallaxes could introduce a systematic error in derived absolute magnitudes. Lutz and Kelker were the first to demonstrate directly and quantitatively how to correct for this bias. It soon became standard practice to apply the Lutz-Kelker corrections, making Tom's name a household word in the field of astrometry.
During his first sabbatical in England, Tom worked with Bernard Pagel at the RGO on the physical nature of the Wilson-Bappu effect. Applying multivariate least squares analysis to stellar atmosphere data he demonstrated that line widths depend on the basic physical parameters, effective temperature and surface gravity, as well as metallicity.
During this same year at the RGO, Tom worked with Andrew Murray on statistical studies of trigonometric parallaxes. This subject had taken on renewed importance with the 1976 proposal by William van Altena to compile a new edition of the Yale General Catalogue of Trigonometric Stellar Parallaxes, which would require a thorough re-investigation of the systematic errors in parallaxes obtained at different observatories and revision of the precepts for combining the results. Tom undertook this task, and his 1978 review "Statistics and Parallaxes," presented at an IAU Colloquium in Vienna, established him as a leader in the modem statistical assessment of the accuracy of parallax observations, and led him to a fruitful collaboration with Robert Hanson of Lick Observatory, which he continued to the end of his life. Tom's definitive analysis, published in a series of papers with Hanson between 1980 and 1983, concluding with recommended precepts for the new Yale Parallax Catalogue, probably represents his most significant contribution to astrometry.
Tom Lutz took an active role in the work of IAU Commission 24 (photographic Astrometry), serving on its Organizing Committee and as chairman of the Working Group on Parallax Standards. His major contribution here was his successful proposal that a list of standard stars be selected for observation by all parallax observatories, to allow more reliable comparisons in the future.
Tom's interest in cosmic distances was not limited to trigonometric parallaxes. In the late 1980s he began working on the period-luminosity-metallicity relations and absolute magnitudes of Population II pulsating variable stars, which form an important link between distances in our Galaxy and nearby galaxies. This work, in collaboration with James Nemec, was a major focus of his research during the last two years of his life; his last published paper gives a very extensive statistical analysis of the subject.
During his sabbatical year at CTIO in 1988-89, Tom used his expertise in astrometry to improve methods for locating and tracking stars with the Argus multi-object spectrograph. At the time of his death he was WSU's representative on the Scientific Advisory and Computing Committees of the Astrophysical Research Consortium (ARC) of five universities operating the new 3.5m reflector at the Apache Point Observatory in New Mexico. He was co-Principal Investigator on the NSF grant to build the ARC telescope and was involved in its commissioning. Tom set up a faclhty at WSU for remote data analysis, and Was able to gather data himself for a few months after the start of scientific observing in November 1994.
As an astronomer working in a university mathematics department, Tom Lutz had ready access to the expertise of statisticians, and put this to good use in his own research. He continually encouraged his fellow astronomers to interact with statisticians and to use modern statistical methods. Tom re-introduced normal probability ("probit') plots into astronomy. These are a valuable diagnostic tool, used in many other fields, but too little-known in astronomy.
An ebullient personality who made many friends, Tom bore his full share of administrative responsibilities as well as being an enthusiastic and outstanding educator at all levels. His workshops for local school teachers gave him, and them, particular pleasure. His teaching was of prize-winning quality. He was awarded the 1995 Dean's Teaclting Excellence Award from WSU. As a permanent honor to his memory, this annual Award will be named after him, and endowed by the Thomas E. Lutz Memorial Fund established for this purpose from contributions from his many friends and colleagues. The Fund will also endow Fellowships in Science Education for teachers.
Tom maintained many intetests outside of astronomy. He read voraciously in two favorite subjects - history and mystery. He enjoyed gardening, woodworking and fixing things around the house. From high school to the end of his life, Tom was a dedicated long-distance runner. He enjoyed many other outdoor sports as well, including volleyball, baseball, softball, cross-country skiing and backpacking. He was an enthusiastic photographer, and found many opportunities to combine this interest with his other outdoor activities.
He is survived by his wife, Professor Julie Haynes Lutz, who is Chair of the WSU Department of Mathematics and Director of its Program in Astrono.my, and by his two daughters, three grandchildren, mother, sister, and two brothers. Tom Lutz is also missed and fondly remembered by his many friends and colleagues around the world.
This obituary is based, with permission, on a briefer version prepared for the Quarterly Journal of the Royal Astronomical Society. The authors especially wish to thank Julie Lutz for her invaluable assistance in providing background material on Tom's life and career.