XMM-Newton Publication Statistics
We assessed the scientific productivity and data usage statistics of XMM-Newton by examining 3272 refereed papers published until the end of 2012 that directly use XMM-Newton data. The SAO/NASA Astrophysics Data System (ADS) was accessed for information on each paper including the number of citations. For each paper, the XMM-Newton observation identifiers and instruments were determined and used extract detailed information from the XMM-Newton archive on the parameters of the observations. The information obtained from these sources was then combined to allow the scientific productivity of the mission to be assessed. Since three years after the launch, about 300 refereed papers per year were published that directly use XMM-Newton data. After more than 13 years in operation, this rate shows no decline. Since 2002, around 100 scientists per year have become lead authors for the first time. Each refereed XMM-Newton paper receives around four citations per year in the first few years with a long-term citation rate of three citations per year, more than five years after publication. About half of the articles citing XMM-Newton articles are not primarily X-ray observational papers. The distribution of elapsed time between observations taken under the Guest Observer programme and first article peaks at 2 years with a possible second peak at 3.25 years. Observations taken under the Target of Opportunity programme are published significantly faster, after one year on average. 90% of science time taken until the end of 2009 has been used in at least one article. Most observations were used more than once, yielding on average a factor of two in usage on available observing time per year. About 20% of all slew observations have been used in publications. The scientific productivity of XMM-Newton remains extremely high with no evidence that it is decreasing after more than 13 years of operations.