EXSdetect: Extended X-ray Source Detection


EXSdetect is a Python software designed to detect extended sources in X-ray images down to lowest flux levels, while maintaining robust photometry, high completeness, and low contamination, regardless of source morphology. It is developed mainly to exploit the ever-increasing wealth of archival X-ray data, but is also ideally suited to explore the scientific capabilities of future X-ray facilities, with a strong focus on investigations of distant groups and clusters of galaxies.

EXSdetect combines a fast Voronoi tessellation code with a friends-of-friends algorithm and an automated deblending procedure. The values of key parameters are matched to fundamental telescope properties such as angular resolution and instrumental background.

Presently, EXSdetect is only calibrated for Swift-XRT data. We plan to present a Chandra version by adjusting the parameters according to Chandra ACIS characteristics in the future.


Liu et al. 2013 A&A 549 143 "EXSdetect: an end-to-end software for extended source detection in X-ray images: application to Swift-XRT data"


  EXSdetect_Swift inputimage.fits [options]


You need to have Python in your system, together with a few commonly used Python packages:

  numpy    numerical python package
  scipy    scientific python package
  pyfits   interface to FITS formatted files
It was developed with Python 2.7.

How to use it

Download and unpack the software, put it anywhere you like. Allow execute permission to the file EXSdetect_Swift and run it directly.
  chmod +x YOURDIRECTORY/EXSdetect/EXSdetect_Swift
  YOURDIRECTORY/EXSdetect/EXSdetect_Swift -h
For your convenience, you can add the EXSdetect/ directory to your $PATH in .bashrc:
Or add an alias to your .bashrc:
  alias EXSdetect_Swift=’YOURDIRECTORY/EXSdetect/EXSdetect_Swift’
Then you can call it directory like:
  EXSdetect_Swift -h


  Document.pdf	Document
  Manual.txt	Manual page
  exsdetect.py	The main program
  sweepline.py	The sweep-line Voronoi construction program
  CurveDef_SWIFT.py	Curve Definition for Swift-XRT
  CurveDef_CHANDRA.py	Curve Definition for Chandra ACIS
  EXSdetect_Chandra	Entrance for Chandra ACIS, executable
  EXSdetect_Swift	Entrance for Swift XRT, executable

Last modified: December 2013

Ha ha~, you know where the web page style is stolen from, if you are a X-ray astronomer. I like the "CIAO" website a lot. Grazie, CIAO. I acknowledge the Chandra X-ray Center (CXC) for their excellent work.

Teng Liu Email: lewtonstein@gmail.com