Table Of Contents

Previous topic

Welcome to THELI’s documentation!

Next topic


This Page


Software Description

THELI is a complete image processing system for the reduction of astronomical CCD data. Its software modules cover all necessary tasks from raw images of single- and multi-chip CCD cameras up to astrometrically and photometrically calibrated co-added images. The main focus is on observations in optical wavelengths. A scientific justification for the involved data-calibration modules and the used algorithms is published in the article Astronomical Notes 326, 432 (Erben et al.)

THELI exists in two flavours. This version is command-line based and the user interacts with the system via shell script commands on the UNIX prompt. Mischa Schirmer extended THELI with a Graphical User Interface (GUI) which allows a complete menu-driven and interactive work with THELI. Moreover, he developed additional codes to process Near-Infrared observations. This GUI and the Near Infrared modules are not included in this package but are distributed and documented here.

Beginners in the fields of data processing and imaging pipelines are advised to start with Mischas GUI version. Users who wish to process only a small data set, or who intend to use THELI only occasionally, are also encouraged to use that version. The command-line interface better suits the needs for more involved data processing of complete surveys. It is also the method of choice for long, non-interactive processing runs or if remote processing is necessary. It requires deeper knowledge of THELI internals, and has higher demands on the users computing knowledge, e.g. bash shell scripting.

Software Prerequisites

THELI is based on many external software modules. Most of them are integrated as source code into the distribution package. Furthermore, the following software components are required for a full functional THELI install:

  • A UNIX/Linux machine with a standard scientific computing setup. This includes the GNU Compiler Collection, standard UNIX/Linux tools such as awk, sort, find. The bash shell is required in version 3 or higher.
  • For astrometric calibration THELI can use Emmanuel Bertins scamp, or a modified version of Mario Radovichs Astrometrix. The first option is currently our method of choice.
  • THELI uses the SuperMongo (SM) plotting tool to create control plots. It is non-free but typically available at astronomical institutes.
  • In the astrometric and photometric calibration modules, THELI makes heavy use of Python (required is V2.X with X>=5) and the Python modules pyfits (V1.1 or higher), numpy (V1.3.0 or higher) and matplotlib (V0.98.1 ot higher)

The THELI install setup will test the current configuration of your machine and report unmet dependencies.

Software Download

Please find the latest version of the software at here. You find there also a modified version of Mario Radovichs Astrometrix if you want to use this module for astrometric calibration of your data.

Please find Mischa Schirmers THELI GUI version here

Software Authors and Software License

The software is maintained by Thomas Erben at the Argelander-Institut für Astronomy in Bonn/Germany. Please email_me with your questions, suggestions and comments. THELI is released under the GNU General Public License, version 2.

Core parts of the software were contributed by Mischa Schirmer, Jörg Dietrich and Hendrik Hildebrandt.

THELI is heavily based on public software, in particular from Emmanuel Bertin, Nick Kaiser, Erik Deul, Mario Radovich, and the ESO Eclipse team.


If you use THELI for your own research, please cite it with the article Astronomical Notes 326, 432 (Erben et al.)