Chandra Bibliographic Statistics

Tracking Scientific Productivity:

To evaluate the relative scientific effectiveness of Chandra observations, we have undertaken to compile and study data on related publications. Across institutions and even across disciplines, professional publications and citations represent the most commonly used and accepted method of tracking scientific productivity. See the March 2004 Newsletter article describing this effort.

Basic Annual Bibliographic Statistics (as of 2025-04-20) :

The basic annual bibliographic statistical data for the Chandra X-ray Observatory pertain to papers on Chandra observations. These papers fall into two groups: those that present specific Chandra observations (Category 1) and those that refer to published Chandra results with complementary observations, follow-up analysis, or theoretical analysis (Category 2 with flags A, B, or C). We define these as Chandra Science Papers.

Year	Refereed Chandra Science Papers	Number of Citations to these Papers	All Chandra Science Papers	Observations Published in Refereed Papers *
2000	55	8151	60	104
2001	198	20284	217	439
2002	330	27954	380	1074
2003	431	31759	521	1830
2004	400	26331	497	2233
2005	447	28282	578	3089
2006	549	40283	688	2317
2007	499	32461	610	2325
2008	519	29002	674	4503
2009	432	26750	552	5444
2010	421	25415	534	4050
2011	441	23633	577	5871
2012	453	25631	552	7534
2013	425	23264	518	7470
2014	405	20411	492	6705
2015	429	20723	491	7411
2016	440	19278	530	7473
2017	472	25602	579	11065
2018	459	15579	515	7935
2019	421	11067	471	9748
2020	390	8396	416	13202
2021	378	6821	410	4647
2022	367	5112	378	6299
2023	441	3606	454	6303
2024	500	2255	517	17621
2025	127	319	128	1881
Total	10429	508369	12339

* Note: this is a lower limit since it refers to Category 1 papers only.

The Chandra Bibliography Database:

The Chandra Bibliography Database allows the public to search all Chandra-related articles and to follow links from the data to the literature, as well as from the literature to the data. Thanks to the Astrophysics Data System (ADS), publication data are highly complete, and relatively easy to track. We query the ADS daily for publications related to Chandra or to X-ray astronomy, and we are complete from before Chandra's launch. We review the publications, categorize them by several different parameters, and enter them into the Bibliography Database. For publications that present, analyze, or refer to Chandra data, we determine the ObsIds involved (either from the text or by asking the authors). ObsIds allow links to other information, such as Chandra Proposal Database items like scientific category and proposal type.

(You Know What They Say About) Statistics:

The Chandra Biliography Database allows for the compilation of a large number of publication statistics. We create selected data tables and plots, linked below, which are updated monthly. The resulting plots and statistics have the potential for misinterpretation, unless one is alert to embedded assumptions and details affecting the tally. For instance, most plots linked here (except those by publication year) include only refereed journal articles that present specific Chandra observations, and all plots tally only programs whose observations are complete. We strongly recommend reading both the NOTES and CAVEATS and the DEFINITIONS and CONVENTIONS, as a guide for interpreting the plots linked below. If you have pressing questions or concerns, please contact Paul Green of the Chandra Director's Office.

Plots and Data:

Refereed Chandra Science Papers by Publication Year
Citations to Refereed Chandra Science Papers by Publication Year
Plots and Data for Category 1 papers only

Supporting Documents:

NOTES and CAVEATS
DEFINITIONS and CONVENTIONS