New capabilities have been added to the ACIS Extract (AE) package, an
IDL tool for automated ACIS point source extraction & spectral fitting.
The software and a detailed users' manual are available at
The starting point for AE is cleaned & calibrated x-ray event data,
possibly from multiple ACIS observations, plus a catalog of point
sources derived from that data. The ending point for AE and its several
accessory tools is a set of spectral model fit parameters and light
curves for each source, plus a wide variety of statistical properties of
the sources. The complex data processing tasks falling in between, and
addressed by AE and its several accessory tools, include:
* refining the accuracy of source positions
* assisting the observer in reviewing the catalog for spurious and
* defining extraction regions
* defining source mask regions (to facilitate construction of background
spectra and study of extended emission)
* extraction of source spectra
* extraction & scaling of local background spectra
* grouping of source spectra
* computation of instrument responses (RMF & ARF)
* computation of a PSF fraction curve for each extraction region
* lowering of the ARFs by the PSF fraction curves to improve flux estimates
* computation of light curves and K-S tests for variability
* computation of source median energy time series
* wide-band photometry
* automated spectral grouping & fitting
* review of fitting results, and compilation of results into LaTex tables
* Maximum Likelihood reconstruction of each source neighborhood
Notably, all these tasks are performed in a context that may include
multiple observations of the field. Composite images, light curves,
spectra, ARFs, RMFs, etc. (using all observations) are constructed.
A rich variety of interactive plots are produced showing various source
properties across the catalog.
Posters describing AE were presented at the 2003 HEAD meeting, and at
the Four Years of Chandra Observations symposium.
AE was first released to the Contributed Software site at the CXC in
February 2003. An email to the chandra-users list announcing the
release was unfortunately not delivered due to a technical malfunction.
The changes made since the February release are described in the
What's New section of the manual:
Support provided by NASA contract NAS8-38252 to Gordon Garmire, the
ACIS Principal Investigator.
Patrick S. Broos email@example.com
UVOT Software Systems Engineer
Swift Explorer Project My office 814-865-5509
Penn State University
2565 Park Center Blvd., Suite 200 FAX 814-865-6854
State College, PA 16801
http://www.swift.psu.edu project office 865-7750
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