Thomas H. Markert died on 19 June 1996, after a long battle with cancer. Tom received his BS from Caltech in 1970 and his PhD from MIT in 1975, both in physics, joining the AAS the next year. He remained at MIT throughout his career, first as a member of the research staff and then as Principal Research Scientist in the Center for Space Research.
Tom's professional life began in the early days of X-ray astronomy, and he was to play major roles in several of the key satellites that helped to establish and exploit this flourishing discipline. His work on the MIT OSO-7 experiment led to a series of papers on galactic X-ray sources and to one of the early catalogs of intensities, multi-band spectra, and variability of X-ray sources.
Tom was the instrument scientist for the Focal Plane Crystal Spectrometer (FPCS) on the Einstein Observatory (HEAO-2), helping to design, build, test, and then use this instrument to obtain the first high resolution spectra of X-ray emission lines from a variety of galactic and extra-galactic sources. His work with the FPCS helped to pioneer the use of plasma diagnostics in celestial X-ray astronomy. One major contribution was his measurement of Doppler shifts in X-ray lines from the supernova remnant Cas A, giving the first direct indication of the bulk velocity and, consequently, the kinetic energy, of the hot X-ray-emitting stellar ejecta that dominate the mass of this young remnant. He also helped establish that non-equilibrium ionization conditions prevail in SNRs. He used the imaging instruments on Einstein to pursue studies of X-ray sources in galaxies of the Local Group.
Tom then became the Project Scientist and CoInvestigator for the High Energy Transmission Grating Spectrometer (HETG) and the Bragg Crystal Spectrometer (BCS) investigations on the Advanced X-ray Astrophysics Facility (AXAF). He made critical contributions to the technology and to the management of these instruments, both of which involved innovative technology development. Although the BCS was eventually deleted from AXAF when it was descoped, Tom helped move the HETG from conceptual design to a nearly flawless flight instrument by the time of his death. He also lent his expertise to the early establishment of the AXAF Science Center.
Tom's scientific accomplishments are more than matched by the very profound impact he had on students, colleagues, and friends. He was an extraordinarily warm and caring individual, universally liked and respected for his honesty, steadfastness, selflessness, and extreme humility. His private life was devoted to caring for those in need: together with his wife, Angie, he helped many hundreds. He was instrumental in creating the Hospitality Program, opening his home to dozens of families of patients at Boston hospitals, and played leadership roles in his church and his community.
As a fitting memorial, one of the HETG grating facets that will be launched in August 1998 with AXAF is inscribed with Tom's name.
Photo (available in PDF version) courtesy Claude Canizares.