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eLISA Data Processing Centre. Volker Beckmann APC, Francois Arago Centre A. Petiteau, E. Porter, G. Auger, E. Plagnol, P. Binétruy. Data Processing Centre. Thinking about eLISA data analysis The data stream of eLISA Ground segment structure of eLISA

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eLISA Data Processing Centre

Volker Beckmann

APC, Francois Arago Centre

A. Petiteau, E. Porter, G. Auger, E. Plagnol, P. Binétruy

Data processing centre
Data Processing Centre

  • Thinking about eLISA data analysis

  • The data stream of eLISA

  • Ground segment structure of eLISA

  • Tasks of the Data Processing Centre (DPC)

  • Structure of the DPC

V. Beckmann

Thinking about elisa data analysis
Thinking about eLISA data analysis

  • eLISA is a large and important mission

  • Data have to be easy to access, understand, analyse, display

  • Community appreciates real-time information (risk?)

  • Colleagues want the possibility to verify

  • Make all data public (raw to high level)

  • Provide (open source) s/w which allows community to re-do our analysis -- and potentially include own algorithms

  • Speak their language: astronomers like fits format, catalogs in their formats, easy access through established data bases

  • Listen to wishes and ideas from the

    larger community in order to achieve

    maximum support for our ambitious


Photo: Ted Carnaham

Data stream
Data Stream

  • Omni-directional observations, no ‘pointed observations’, no observers

  • The accumulated data provide the best sensitivity and include all information

  • Level 0: raw telemetry

  • Level 1: fully calibrated and corrected Time Delay Interferometry (TDI) data

  • Level 2: source identification, parameter extraction, model parameters and probability density function of sources. Transient identification

  • Level 3: source catalogue, (astro)physical source parameters, strain time series

  • Use different algorithms in the production of Level 2/3 data

  • Regular (e.g. weekly) reprocessing of the accumulated data stream

V. Beckmann

Data stream1
Data Stream

  • The data volume is small, the processing demand is large

  • 5 Hz measurements

  • 30 channels ‘mother’ spacecraft, 14 channels on each of the daughter spacecrafts

  • Housekeeping data (at various frequencies)

  • 11 kbs  << Gbyte per day

  • Few Gbyte per day (incl. everything L0-L3)

Ground segment
Ground Segment

Responsibility for data processing shared between MOC/SOC (ESA), IOTs (member states) and Data Processing Centre (member states)

Tasks of the dpc
Tasks of the DPC

  • Data Processing Centre (DPC) provides two analysis chains:

  • Quick look analysis (QA) and standard analysis (SA) pipeline.

  • QA: simplified version of SA. To run on a daily basis on the incoming data stream. Visualize data. Identify potential problems (beyond from what MOC/SOC) can spot.

  • SA: run full analysis on the accumulated data once a week

  • Integrate algorithms developed by the eLISA consortium members

  • Develop, test, maintain, document s/w chains

  • Distribute and provide user support for the SA pipeline

  • Report Level 2/Level3 results back to SOC for potential event announcements to the eLISA consortium/community.

  • Ensure mature level of s/w applied in the DPC

  • “Listen” to eLISA consortium, stay flexible

Structure of the dpc
Structure of the DPC

  • Data Processing Centre (DPC) does not define the algorithms, does not (exclusively) provide scientific interpretation.

  • Changes in algorithms and in definition of products are to be approved by a Change Control Board (CCB) of the eLISA consortium.

  • Technical changes and quality control (version control, unit testing, etc.) handled locally at the DPC

  • Though tasks at DPC are not ‘scientific’ deep understanding of eLISA science necessary at DPC management level

  • Several member states can contribute to DPC (FTE or being in charge of certain tasks).

Structure of the dpc1
Structure of the DPC

  • Project scientist and project manager organise the work of the DPC and ensure contact with eLISA consortium, IOTs, and ESA (MOC/SOC)

  • Start early (but not too early!): 5 yrs before launch (1 year earlier for management)

  • Ramp up staff until launch

  • Important aspects: Quality control (testing!), maturity of s/w chain, be ready for changes after launch, maintain knowledge over the whole mission duration (including post mission activities)

  • DPC relies strongly on knowledge of the IOTs and the eLISA consortium

  • Hardware costs: mainly computing (~1,500 CPU during science operations)

Fran ois arago centre
François Arago Centre

  • Project at APC, located across the street

  • Cluster, 640 CPU, 100 kW cooling, 100 TByte disk

  • 10 Gbit/s connection

  • 2 video conference rooms

  • Concurrent Design Facility (used e.g. for eLISA/NGO)

  • 2 meeting rooms

  • Offices on demand

  • Hard- and software support

  • Projects: LISA-PF, Euclid, CTA, INTEGRAL, HESS…

The dpc as member state contribution
The DPC as member state contribution

  • Providing the DPC by ESA member states, reduces the costs for ESA

  • I.e. the more tasks on data analysis/storage/distribution/support we as consortium can provide, the lower the costs to ESA

  • This has been done before: e.g. in INTEGRAL, the science data centre is considered as “5th instrument” of the mission (incl. specific consortium for the SDC, I.e. with SDC under control of the member states).

  • Competing with ESAC

  • CNES starts a phase-0 study (approved today!) concerning the eLISA data processing centre requirements, risks, options, etc.

  • Kick-off meeting in December 2012, phase 0 to start January 2013, lasting one year.


  • eLISA has to provide excellent service to the whole

    community, before, during, after the mission

  • Open to ideas, requests, wishes, concerns

  • DPC processes L1 to L3 data

  • Small data volume, large processing needs

  • Quick look and standard analysis (simulator not included)

  • Development, integration, testing, maintenance, documentation, user support

  • Algorithm development by eLISA consortium (not DPC), knowledge about instruments with IOTs

  • Start 2017 with 2 FTE management, 2018 first s/w integration activities

  • 58 FTE*years until launch

  • French community is ready to provide the Data Processing Centre services to the eLISA consortium!

  • See also Beckmann et al. 2012, “The eLISA/NGO Data Processing Centre”, ASP Conf. Series 467

V. Beckmann