Version 21.0: June 16, 2023


Updated for SAS Version 21.0

Questions and Problems Should Be Sent to xmmhelp@athena.gsfc.nasa.go


Formerly: Code 662, NASA/Goddard Space Flight Center, Greenbelt, MD 20771
Currently: Retired and Enjoying Life to its Fullest



Currently: The Henry A. Rowland Department of Physics & Astronomy, Johns Hopkins University, Baltimore, MD 21218
Futurely: Thinking about Retirement


The following manual/cookbook is for the use of the XMM-Newton Extended Source Analysis Software (XMM-ESAS, or just ESAS) suite of packages for the analysis of imaging mode EPIC MOS and pn observations. ESAS creates both model quiescent particle background spectra for use in spectral fitting and exposure-corrected, background-subtracted (particle, soft proton, and solar wind charge exchange) images. The spectra and images are produced for user-defined regions within an observation field of view. The output files are in standard FITS format. Software for mosaicking multiple observations of not necessarily co-aligned pointings is included in this package.

This version of ESAS is significantly different from previous versions of ESAS. The original ESAS relied very heavily on scripts, in part to manage the large number of files required to produce the background images and spectra. The goal was to allow the scripts to do everything that did not require direct human intervention. As a result, ESAS required a very rigid directory/file name structure. As part of an effort to implement ESAS more closely into SAS, the ESAS routines have been modified 1.) to be less dependent upon the rigid directory/file name structure, 2.) to make the routines more modular, 3.) reduce the number of files produced, and 4.) clean up a number of loose ends, unclear usage, and the like. As a result, the bulk of the scripting has been moved out of ESAS. This is unlikely to be a traumatic change; users have become more accustomed to scripting in a variety of languages.

A new method of constructing the quiescent particle background spectra should arrive with SAS V22.0.

We would like to thank members of the MOS and pn hardware and software teams, the XMM-Newton SOC at the European Space Astronomy Centre (ESAC), and other members of the EPIC Background Working Group for their contributions that ranged from helping us to understand instrument and software issues to the identification of filter-wheel closed observations in the archive. Carlos Gabriel and Aitor Ibarra of the SOC and Brendan Perry of the NASA GOF deserve special thanks for their efforts in converting XMM-ESAS routines into SAS tasks. Ignacio de la Calle PĂ©rez also deserves our thanks for being the point person at the SOC for responding to users' questions about ESAS. We would also like to thank the many users that have provided comments that have been used to improve this software. Suggestions and comments are always welcome.

Users of this package should be aware of the informational web pages covering the background issues of EPIC observations at: and the EPIC Calibration Status document at: