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The aXe Software Package


The aXe software package is designed for the extraction, calibration, visualization, and simulation of spectra from slitless spectroscopic instruments.

The overall aXe package consists of three components:

aXe was originally developed by the Space Telescope - European Coordinating Facility (ST-ECF), a unit of the European Space Agency (ESA) hosted by the European Southern Observatory (ESO) headquarters in Garching, Germany. As of January 1, 2011, the Space Telescope Science Institute (STScI) has taken responsibility for support and distribution of the software.

To report problems, or seek help on aXe issues not addressed in these webpages, please contact


aXe can be installed as part of Anaconda 3. It requires a Python 2.7 installation, Pyraf , pydrizzle and multidrizzle. It is therefore recommended that it be installed as a new Anaconda 3 environment, using the following steps:
Note: We have verified that Anaconda3 version 5.1.0 works and if you encounter problems, please install that version specifically from

aXe News

A new Jupiter based cookbook using aXe and WFC3 slitless data is now available at The cookbook shows how to run aXe and aXedrizzle and comes with test data.

aXe is currently distributed as part of Anaconda and the STScI astroconda channel.

aXe is currently distributed as past of Ureka.
The latest version, equivalent to the older STSDAS IRAFX distribution, can be obtained from the SSBX development build.

STSDAS 3.16 has been released, but aXe users should note that the version of aXe bundled there ONLY supports processing with Multidrizzled direct images. Support of processing with AstroDrizzled products is currently provided only in versions of aXe in IRAFX with release dates after 2013-03-28. aXe software release notes can be found at The WFC3 IR grism cookbook has been updated to accurately reflect availability of AstroDrizzle support in IRAFX.

Fix for iolprep bug reported on 2013-03-13 in aXe v2.x available in IRAFX (the STSDAS testing environment).

Bug Report 2013-03-13 (IRAFX 2013-03-07; aXe v2.x iolprep)

The WFC3 IR grism cookbook has been updated to reflect changes made to the aXe software to accommodate AstroDrizzle image products. An updated manual will be available shortly.

aXe was originally designed to support Multidrizzle style astrometric information. Current (aXe v2.3) and earlier versions of the software rely on output files from the Multidrizzle process to transform object pixel coordinates between the user supplied "drizzled" direct image and corresponding spectral images. We are currently working on updating aXe to accommodate the use of new Astrodrizzle products, and maintain back-compatability with Multidrizzle.
A version of aXe, where iolprep and fcubeprep has been modified for compatibility with Astrodrizzle, is available via IRAFX (the STSDAS testing environment). Work and testing of these tasks are still on-going. Release notes can be found here.