Astrophysics

Chandra X-ray Observatory

Pointed Observatory · Directed · Agency-led · Launched on July 23, 1999 · Extended Mission · LCC: $2.7B/$7.5B (2025 $)Life-cycle cost: NASA’s reported cost to build, launch, and operate a mission through its prime mission, plus documented partner contributions, in 2025 dollars. Extended missions are not included. Methods · Wikipedia

Scope Active Mission WindowActivePapers published from the first full month after science operations begin through two years after the mission ends. Citations are counted through the third calendar year after each paper appears. For Chandra, papers published September 1, 1999 to January 1, 2024. Methods LifetimeLifetimeEvery tracked publication to date, with every citation to date. For Chandra, papers published from 1999 to November 3, 2026. Methods
Tracked publicationsTracked publications: peer-reviewed papers we found that name the mission or its instruments in their titles, abstracts, or keywords. Papers that used the data without naming it are missed. Methods9,224
CitationsCitations: every citation these publications have drawn to date. Older missions have had longer to collect them. Methods465,262
Citation indices
h-indexh-index: the largest h such that h papers have at least h citations each. It only grows with time, so older missions score higher. Methods244
g-indexg-index: the largest g for which the g most-cited papers together hold at least g² citations. Like the h-index, but it lets the most-cited papers count for more. Methods372
m-indexm-index: a mission’s h-index divided by the years since its first peer-reviewed paper. It falls every 1 January even when nothing else changes; the figure shown is as of November 3, 2026. It also discounts the long operating life that larger missions paid for. Methods8.7
toritori (total research impact, from SciX): for every paper citing one of the mission’s papers, 1 divided by the citing paper’s reference count times the cited paper’s author count, summed, with self-citations removed. It favors citations from papers with short reference lists and from outside the mission’s own authors. Computed over the tracked citation graph, which can be slightly incomplete. Always over every tracked publication to date, whichever scope is chosen. Methods1,723
riqriq (research impact quotient): 1,000 times the square root of tori, divided by the years since the mission’s first paper. A rate, not a total, so it does not keep growing with age the way the h-index and tori do. Like tori, always over every tracked publication to date. Methods1,431

Publications and citations by year (lifetime)

Publications per yearCumulative citations

Institutional contributions (lifetime)The institutions SciX lists for each paper’s authors, as printed on the paper, located through the Research Organization Registry. A square counts a paper once, however many of its authors worked there. Methods

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Tracked publications over the lifetime (9,224)

All publications CSV · JSON

  1. On the Absorption of X-Rays in the Interstellar Medium

    Wilms, J., 2000, ApJ

    3,963 lifetime citations

  2. First Sagittarius A* Event Horizon Telescope Results. I. The Shadow of the Supermassive Black Hole in the Center of the Milky Way

    Event Horizon Telescope Collaboration, 2022, ApJ

    2,498 lifetime citations

  3. A Direct Empirical Proof of the Existence of Dark Matter

    Clowe, Douglas, 2006, ApJ

    2,248 lifetime citations

  4. Collisional Plasma Models with APEC/APED: Emission-Line Diagnostics of Hydrogen-like and Helium-like Ions

    Smith, Randall K., 2001, ApJ

    2,037 lifetime citations

  5. X-ray spectral modelling of the AGN obscuring region in the CDFS: Bayesian model selection and catalogue

    Buchner, J., 2014, A&A

    1,713 lifetime citations

  6. The Great Observatories Origins Deep Survey: Initial Results from Optical and Near-Infrared Imaging

    Giavalisco, M., 2004, ApJ

    1,684 lifetime citations

  7. Chandra Sample of Nearby Relaxed Galaxy Clusters: Mass, Gas Fraction, and Mass-Temperature Relation

    Vikhlinin, A., 2006, ApJ

    1,345 lifetime citations

  8. Cosmological Evolution of the Hard X-Ray Active Galactic Nucleus Luminosity Function and the Origin of the Hard X-Ray Background

    Ueda, Yoshihiro, 2003, ApJ

    1,097 lifetime citations

  9. VISTA Variables in the Via Lactea (VVV): The public ESO near-IR variability survey of the Milky Way

    Minniti, D., 2010, NewA

    1,036 lifetime citations

  10. Chandra Cluster Cosmology Project III: Cosmological Parameter Constraints

    Vikhlinin, A., 2009, ApJ

    1,031 lifetime citations

  11. A Systematic Study of Radio-induced X-Ray Cavities in Clusters, Groups, and Galaxies

    Bîrzan, L., 2004, ApJ

    904 lifetime citations

  12. The synthesis of the cosmic X-ray background in the Chandra and XMM-Newton era

    Gilli, R., 2007, A&A

    869 lifetime citations

  13. Chandra X-Ray Spectroscopic Imaging of Sagittarius A* and the Central Parsec of the Galaxy

    Baganoff, F. K., 2003, ApJ

    824 lifetime citations

  14. Constraints on dark energy from Chandra observations of the largest relaxed galaxy clusters

    Allen, S. W., 2004, MNRAS

    822 lifetime citations

  15. Infrared Luminosity Functions from the Chandra Deep Field-South: The Spitzer View on the History of Dusty Star Formation at 0 <~ z <~ 1

    Le Floc'h, Emeric, 2005, ApJ

    807 lifetime citations

  16. Shocks and cold fronts in galaxy clusters

    Markevitch, Maxim, 2007, PhR

    803 lifetime citations

  17. Compact Object Modeling with the StarTrack Population Synthesis Code

    Belczynski, Krzysztof, 2008, ApJS

    790 lifetime citations

  18. The Chandra Deep Field North Survey. XIII. 2 Ms Point-Source Catalogs

    Alexander, D. M., 2003, AJ

    765 lifetime citations

  19. Detection of an Unidentified Emission Line in the Stacked X-Ray Spectrum of Galaxy Clusters

    Bulbul, Esra, 2014, ApJ

    765 lifetime citations

  20. An Overview of the Performance and Scientific Results from the Chandra X-Ray Observatory

    Weisskopf, M. C., 2002, PASP

    726 lifetime citations

How we found these papers

We searched NASA’s Science Explorer (SciX) for peer-reviewed articles naming Chandra in the title, abstract or keywords; standard filters drop articles that are not peer-reviewed and magazine pieces.

((=abs:"Chandra X-ray" OR =abs:"Chandra observations" OR =abs:"Chandra observation" OR =abs:"Chandra data" OR (abs:Chandra AND (=abs:"X-ray" OR =abs:"X-rays" OR =abs:xray OR =abs:xrays) AND NOT (abs:Chandrayaan OR abs:Chandrayan OR =abs:"Himalayan Chandra Telescope")) OR (abs:Chandra AND collection:astronomy AND NOT (=abs:"Himalayan Chandra Telescope" OR =abs:"Harish-Chandra" OR =abs:"Harish Chandra" OR =abs:"Chandra Wickramasinghe" OR abs:Chandrayaan OR abs:Chandrayan OR abs:glacier OR abs:glaciers OR =abs:"Chandra basin" OR =abs:"Chandra valley")) OR ((abs:ACIS OR abs:HETG OR abs:HETGS OR abs:LETG OR abs:LETGS OR abs:CXO) AND (=abs:"X-ray" OR =abs:"X-rays" OR =abs:xray OR =abs:xrays) AND collection:astronomy) OR (abs:HRC AND (abs:ACIS OR abs:HETG OR abs:HETGS OR abs:LETG OR abs:LETGS)) OR =abs:"Advanced CCD Imaging Spectrometer" OR =abs:"High Energy Transmission Grating" OR =abs:"High Energy Transmission Gratings" OR =abs:"Low Energy Transmission Grating" OR =abs:"Low Energy Transmission Gratings" OR facility:CXO OR facility:Chandra)) AND property:refereed AND doctype:article AND pubdate:[1999-09 TO 2040-01] AND NOT bibstem:("A&R" OR "ACPD" OR "AIASJ" OR "AMTD" OR "AeAm" OR "AirSp" OR "AsNow" OR "AsUAI" OR "AvWST" OR "BGD" OR "C&E" OR "C&T" OR "CAPJ" OR "CliPD" OR "E&S" OR "ENews" OR "ESDD" OR "ESSDD" OR "ESuDD" OR "GID" OR "GMDD" OR "GeCAS" OR "HESSD" OR "IrAJ" OR "JCos" OR "JRASC" OR "LAstr" OR "MNSSA" OR "Met" OR "NHESD" OR "NPGD" OR "NewSc" OR "OcScD" OR "Orion" OR "PhT" OR "PhTea" OR "PhuZ" OR "PhyOJ" OR "PhyW" OR "PlR" OR "SOILD" OR "SciAm" OR "SpFl" OR "TCD" OR "ZemVs")

Open in SciX

Added after review (2)

  1. Accurate X-ray position and multiwavelength observations of the isolated neutron star RBS1774 X-ray position of RBS1774 from a Chandra High Resolution Camera observation. Decision 🤖
  2. Cassiopeia A: Supernova explosion and expansion simulations under strong asymmetry conditions Cassiopeia A simulations analysing Chandra and NuSTAR observations of the ejecta. Decision 🤖

Removed after review (5)

  1. Type-Ia Supernova Rates and the Progenitor Problem: A Review "Sub-Chandra" refers to sub-Chandrasekhar-mass white dwarfs, not the observatory. Decision 🤖
  2. Technology developments needed for future X-ray astronomy missions Technology needs for future X-ray missions; mentions Chandra only as a predecessor. Decision 🤖
  3. Soft X-ray performance of an optimised charge-coupled device for astronomy Ground tests of a CCD for the SMILE mission; mentions Chandra only for comparison. Decision 🤖
  4. The NewAthena mission concept in the context of the next decade of X-ray astronomy Mission concept for ESA's NewAthena X-ray observatory; mentions Chandra only as context. Decision 🤖
  5. Soft X-ray quantum efficiency of a commercial CMOS imaging sensor Lab test of a CMOS sensor for future missions; names Chandra only for comparison. Decision 🤖