The Software Legacy of the Planck Mission

March 24, 2015

The Planck mission to survey the Cosmic Microwave Background (CMB) has not only advanced our understanding of the Universe, it also created advanced software systems for data analysis. Three interrelated software packages, which were developed at the Max Planck Institute for Astrophysics (MPA) specifically for the Planck mission, are now publicly available for use in other projects: the basic Planck simulation package to generate mock observations with Planck and other CMB experiments, the “ProC” workflow engine to define and execute scientific data analysis workflows, and the data management component “DMC” to store and organize the results of complex data processes.

The analysis of data from the Planck mission is a challenging task. The telescope was scanning the whole sky in small stripes and at nine different frequencies, continuously over several years. To convert the huge number of individual observations into integrated maps of the whole sky, the raw data streams have to be checked and calibrated. Afterwards, sky maps are constructed for the nine frequency channels and those maps are analysed for both astrophysical foreground signals and for their cosmological information content. Furthermore, this complex data analysis has to be verified with simulations, which take the relevant cosmological, astrophysical, and instrumental effects into account.

Fig.1: The ProC workflow engine automates recurring data processes running on single machines or even on supercomputers. Together with the data management compontent it tracks and documents the changes made to data, allowing full retraceablity. — **Fig.1:** The ProC workflow engine automates recurring data processes running on single machines or even on supercomputers. Together with the data management compontent it tracks and documents the changes made to data, allowing full retraceablity.

**Fig.1:** The ProC workflow engine automates recurring data processes running on single machines or even on supercomputers. Together with the data management compontent it tracks and documents the changes made to data, allowing full retraceablity.

To support these complex procedures, the Planck software group at MPA provided essential parts of the Planck software infrastructure; in particular a simulation package, a workflow engine and a database front end. Although specifically designed for the requirements of the Planck project, these software packages are useful for a larger community, as they facilitate generic tasks in CMB data analysis as well as other data driven research areas.

The ProC suite for workflows should have the broadest applicability. It consists of a graphical user interface to construct complex data processing workflows out of a given set of computer programs. The ProC workflow engine to actually execute these workflows on computing clusters or in a computational grid. These are complemented by the data management component to store and organize all data products. The user can, for example, specify that only data products which are affected by a change in the input data are updated selectively, avoiding unnecessary computations. As it is very flexible, the ProC suite satisfies basic needs of data processing centres, which have to be able to restructure their data processing along with the development of a project.

Fig.2: The graphical editor allows the easy defintion of workflows. It supports the use of loops, conditions and recursion. Parameters of the incorporated programs can be defined here. — **Fig.2:** The graphical editor allows the easy defintion of workflows. It supports the use of loops, conditions and recursion. Parameters of the incorporated programs can be defined here.

**Fig.2:** The graphical editor allows the easy defintion of workflows. It supports the use of loops, conditions and recursion. Parameters of the incorporated programs can be defined here.

The Planck simulation package takes a cosmological model specified by the user and calculates a potential CMB sky consistent with this model, including astrophysical foregrounds, and then performs a simulated observation of this sky. This Simulation embraces many instrumental effects such as beam convolution and noise. Alternatively, the package can simulate the observation of a provided sky model, generated by another program such as the Planck Sky Model software. The Planck simulation package does not only provide Planck-like data, it can also be easily adopted to mimic the properties of other existing and upcoming CMB experiments. Therefore, it is a valuable and generic tool for CMB research.

Fig.3: The data management component allows access to the data without knowledge of the database backends. Data can be visualized and exported. Also the creation history of a data product can be followed here. — **Fig.3:** The data management component allows access to the data without knowledge of the database backends. Data can be visualized and exported. Also the creation history of a data product can be followed here.

**Fig.3:** The data management component allows access to the data without knowledge of the database backends. Data can be visualized and exported. Also the creation history of a data product can be followed here.

The Planck software development at MPA was funded by the German Space Administration of the German Aerospace Center on behalf of the Federal Ministry for Economic Affairs and Energy as well as by the Max Planck Society. This development was led by Matthias Bartelmann until 2003 and by Torsten Enßlin since then.

Planck is a project of the European Space Agency (ESA) with instruments provided by two scientific consortia funded by ESA member states and led by Principal Investigators from France and Italy, telescope reflectors provided through a collaboration between ESA and a scientific consortium led and funded by Denmark, and additional contributions from NASA (USA).

Torsten Enßlin

Links:

Planck Mission
ProC workflow engine
Planck Sky Model
Planck Legacy Archive
Planck Simulation Package

Contact:

Dr. Torsten Enßlin
Max-Planck-Institut für Astrophysik
Tel.: +49 89 30000-2243
email: tensslin(at)mpa-garching.mpg.de

The Software Legacy of the Planck Mission

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