Over the past 40 years, HEAD has grown from a group of about 10 scientists to a combined staff of approximately 300 including about 90 scientists and 30 postdoctoral fellows. The division includes the Chandra X-ray Center which operates the Chandra X-ray Observatory, and the budget for research and operations totals about $75M, mostly from external contracts and grants. The AD's have included Riccardo Giacconi (1973-1981), Harvey Tananbaum (1981-1991; CXC director 1991-2014; member NAS), Steve Murray (1992-2003; PI HRC, CfA Deputy Director for Science 2005-2010), Roger Brissenden (2003-2010; CXC manager 1993-; CfA Deputy Director 2010-), William Forman (2010-2021), and Randall Smith (2021-).
The primary focus of HEAD has been a series of major X-ray astronomy missions including Uhuru (1970-1973), Einstein (1978-1981), and Chandra (launched 23 July 1999). In addition, members of the division made major contributions to ANS, HEAO-1 (1977-1979), ROSAT (1990-1999) and a series of solar experiments including TRACE (launched July 1999), Hinode (launched Sept. 2006), and SDO (launched Feb. 2010).
The Einstein Observatory (nee HEAO-B), the second of NASA's three High Energy Astrophysical Observatories and the first fully imaging X-ray telescope, was developed and operated by HEAD. With angular resolution, moderate field of view, and a sensitivity several 100 times greater than any previous mission, the Einstein Observatory completely altered our view of the X-ray sky with observations spanning the full range of celestial objects including planets, stars, normal galaxies, collapsed objects from stellar mass black holes to AGN, clusters of galaxies, and detailed observations of the components of the X-ray background. It was also the first NASA X-ray mission to provide a Guest Observer program. In addition to managing the development of the observatory and its X-ray mirrors, HEAD provided the two imaging focal plane instruments (the High Resolution Imager and Imaging Proportional Counter).
Following the Einstein era, HEAD participated in the ROSAT mission (ROSAT Science Data Center) with the development of the second generation High Resolution Imager and development and participation in community-wide software tools.
Currently, HEAD operates the Chandra X-ray Observatory, one of NASA's Great Observatories, named in honor of Subrahmanyan Chandrasekhar (Nobel Prize in Physics, 1983). With its subarcesecond angular resolution and large effective area, Chandra has revolutionized the study of the X-ray background, normal and active galaxies, supernova remnants, planets, and galaxy clusters. During the development phase of the Chandra Observatory (nee AXAF), HEAD provided guidance on the development of the X-ray optics and developed a third-generation High Resolution Camera (HRC). As directed by NASA, HEAD operates the Chandra X-ray Observatory, solicits and plans observations, and provides data analysis tools for the community.
HEAD maintains a strong interest in new missions with a team working on instruments and concepts for future missions. Major efforts include laboratory development of high-resolution lightweight optics and high energy resolution microcalorimeters. Studies and planning for the future include concepts for Lynx (formerly SMART-X), high angular resolution telescopes with areas many times that of Chandra.
The Solar, Stellar, and Planetary Sciences (SSP), part of HEAD, maintains an operations center for Hinode. HEAD also manages the NASA Astrophysics Data System with 14 sites around the world containing more than 5 million entries. HEAD is a partner with GSFC in the HEASARC data archive.
Following Riccardo Giacconi’s passing in 2018, a memorial symposium was organized by the Space Telescope Science Institute, Center for Astrophysics | Harvard & Smithsonian, Johns Hopkins University, the European Southern Observatory, and Associated Universities, Inc. The program and presentations from this symposium can be found here.