organizations of esa’s x-ray observatory missions: the...

Examples of Ground segment organizations of ESA’s X-ray

observatory missions:

the cases of LOFT and XIPE

E. Bozzo – University of Geneva (Switzerland)

The overall structure of the LOFT ground segment has been designed in collaboration with ESA to maximize the science return of the mission, optimize the usage of resources and taking into account that:

- for the LOFT mission it is important to identify relevant transient events and follow statechanges in the observable sources to optimize the observational program QLA conceptand data processing strategy

- The on-board LBAS will transmit VHF messages to communicate rapidly (<30 s) thedetection of bright impulsive events on the ground. The prompt diffusion of these alerts tothe science community at large can significantly improve the science return of the missionat modest costs integration of the LBAGS in the LOFT SGS

Data products

Raw telemetry: science telemetry + (preliminary) auxiliary data (e.g., electrical calibration data, pedestal data, science rate-meters, orbit prediction files, housekeeping data).

Level 0: binary FITS files for the 2 instruments (LAD: FITS event files; WFM: photon by photondata, images sliced in time and energy, rate meters, spectra). On-board calibrations areapplied to both the LAD and WFM data.

Level 1: all corrections (such as aspect correction, time calibration, barycentric corrections) and instrument-specific calibrations (such as detector gain and good-timing information) are applied to level 0 data to obtain cleaned event files.

Level 2: pre-defined science products (LAD data: light curves, energy and power spectrum, photon lists for the observed target; WFM data: sliced images in time and energy - LBAS data are preserved in full energy and time resolution (NOTE: level 2 products are also used for the QLA).

Level 3: enhanced, higher level, scientific products derived from Level 2 data

Data products: NRT and CONS

Level 0, Level 1, Level 2 data can be both “Near Real Time” and “CONSolidated”

NRT - Preliminary WFM data are provided within 2 orbits (3 h) for QLA purposes (preliminary

attitude and time correlation data, to be used for the NRT data products, will be derived from the on-board GPS system and information from the star trackers)

- Preliminary LAD data for QLA and observations progress checks are provided within 1 day(the difference between the two instruments is due to the required reliability in data transmission)

- Level 2 standard data products are extracted for inspection as soon as new NRT data arrives

CONS- Consolidated data and consolidated auxiliary files (with Flight Dynamics) are provided within 1 week and are used for the final scientific analysis.

NB: Level 3 are extracted only from CONS data.

Preliminary data policy

- WFM data: public immediately (QLA products are also made immediately available to the science community)

- LAD data: proprietary period of 1 year (QLA products used only at SOC to communicate with the science PI and optimize pointings strategy/observational plan – i.e. continue/interrupt an observational campaign)

Operational Ground Segment - Main LOFT Ground Stations (Kourou, Malindi):

o about 6.7 Gbit of data every 90 minutes (~110 Gb/day)

- Mission Operation Center (MOC):o commanding of the spacecraft and instruments o ensuring the spacecraft safety and health o provision of Flight Dynamics support o all communications with the satellite through the ground stations (upload of the

platform and payload telecommands, reception of telemetry) o collecting the science data and the transmission to the SOCo providing the raw telemetry, housekeeping and auxiliary data to the SOCo Providing the telecommand history and other auxiliary data (including attitude

history, time calibrations and barycentric corrections) to the SOC (WFM QLA within 2 orbits!)

Science Ground Segment- Science Operation Center- Instrument Operation Centers- Science Data Center- LOFT Burst Alert Ground Segment (LBAGS)

- Science Operation Center (SOC):o Mission planning and proposals handlingo Automatically process lower level data (Raw to Level 0 and Level 0 to Level 1 data

processing)o LOFT Science Data Archive (data and software distribution to the users)o Observation and performance simulator o User Support and mission outreach

Science Ground Segment- Science Operation Center- Instrument Operation Centers- Science Data Center- LOFT Burst Alert Ground Segment (LBAGS)

- Instrument Operations Centers (IOCs, one per instrument):o through national funding o deep expertise of the payloado support to ESA for payload system integration on the spacecraft, maintenance,

operations and calibration (provide required knowledge on the instruments to ESA through the Instrument Operation Scientists – partly located at IOCs, partly at SOC)

o characterize and calibrate the instrument responses (provide calibration data)o monitor the science performance of the instruments, long-term trend analysis of

instrument performanceo maintain the on-board software (OBSW)o maintain the on-board databaseo raise anomaly reports o support the investigations of anomalies

Science Ground Segment - Science Operation Center- Instrument Operation Centers- Science Data Center- LOFT Burst Alert Ground Segment (LBAGS)

- Science Data Center (SDC):o established through national funding and led by the Univ. of Geneva (Geneva) o providing interactive and pipeline data analysis software, Quick-Look Analysis (QLA)

software, pre-processing software o perform pipeline processing of higher level data (Level 1 to 2 and Level 2 to 3)o lead the data processing software maintenance task o perform sky monitoring and provide the publicly available results to the communityo The SDC will support the IOC in the instrument calibration activities, and provides

support to the LOFT user community related to analysis software, data processing, data quality and data characteristics

o It may organize workshops for training in data analysis and software usageo contributes to the testing and validation of new releases of the LSDA and the overall

SGS operational system.

Science Ground Segment - Science Operation Center- Instrument Operation Centers- Science Data Center- LOFT Burst alert Ground Segment (LBAGS): LAC+VHF stations

- LBAGS:o 15 VHF ground stations deployed around the equator, designed according to the

SVOM heritage and deployed in a sub-set of their sites (or use pre-existing stations from SVOM)

o LOFT Alert Center (LAC): SDC personnel monitor the LBAS alert messages and provides support and feedback to the community to maximize the science return of the mission and the synergy between other facilities operating across the multi-messenger spectrum at the time of LOFT.

The VHF system of ground antennas for LOFT

- Designed on the heritage of previous missions (HETE2, SVOM)- If launched, only 15 out of 36 SVOM antennas will be needed for LOFT (otherwise they are

considered part of the SDC contribution of the consortium to the LOFT SGS).

15 HETE-2 ground VHF antennas around the equator (similar to LOFT)

The augmented VHF network foreseen for SVOM.

An example of the old HETE 2 VHF equipment: antenna + workstation.

Data flow

Processing of raw telemetry into level 0 and 1 data done automatically at SOC as soon as telemetry is provided by MOC

Processing of level 1 data into level 2 and 3 data: done by SDC through the LSDA

Calibrations ingested by IOCs into the LSDA

(Figure from LOFT SOAD)

SDC organization: consortium of several institutes. Coordination guaranteed by the managing through a single entity (distribution of the work-load and the timely achievement of all tasks)

Schedule of SDC activity: planned to match closely SOC milestones.

SDC start the most intense phase of software development in 2016, and provide a firstversion of the most relevant software tools to the SOC about 4 years ahead of launch leavingsufficient time for the SDC-SOC interactions before the SG end-to-end tests starts (about 2years ahead of launch). The complete software delivery to SOC (ESA) is expected from SDC 2years ahead of launch.

(Figure from the SOAD)

XIPE participating InstitutionsBR: INPE; CH: ISDC - Univ. of Geneva; CN: IHEP, NAOC, NJU, PKU, PMO, PurdueUniv., SHAO, Tongji Univ, Tsinghua Univ., XAO; CZ: Astron. Institute of the CAS;DE: IAAT Uni Tübingen, MPA, MPE; ES: CSIC, CSIC-IAA, CSIC-IEEC, CSIC-INTA,IFCA (CSIC-UC), INTA, Univ. de Valencia; FI: Oxford Instruments Analytical Oy,Univ. of Helsinki, Univ. of Turku; FR: CNRS/ARTEMIS, IPAG-Univ. ofGrenoble/CNRS, IRAP, Obs. Astron. de Strasbourg, IN: Raman ResearchInstitute, Bangalore; IT: Gran Sasso Science Institute, L'Aquila, INAF/IAPS,INAF/IASF-Bo, INAF/IASF-Pa, INAF-OAA, INAF-OABr, INAF-OAR, INFN-Pi, INFN-Torino, INFN-Ts, Univ of Pisa, Univ. Cagliari, Univ. of Florence, Univ. of Padova,Univ. of Palermo, Univ. Roma Tre, Univ. Torino; NL: JIVE, Univ. of Amsterdam;PL:CopernicusAstr. Ctr., SRC-PAS; PT: LIP/Univ. of Beira-Interior, LIP/Univ. ofCoimbra; RU: Ioffe Institute, St.Petersburg: SE: KTH Royal Institute ofTechnology. Stockholm Univ.: UK: Cardiff Univ., UCL-MSSL, Univ. of Bath; US:CFA, Cornell Univ., NASA-MSFC, Stony Brook Univ., Univ. of Iowa, BostonUniv., Institute for Astrophysical Research, Boston Univ., StanfordUniv./KIPAC.

The XIPE Science Ground Segment

Enrico BozzoISDC

University of GenevaSwitzerland

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XIPE Science Ground Segment

XIPE Relevant Science Requirements

XIPE will be operated as an observatory, with key science goals to be achieved through observations that can last up to a few Ms

A large fraction of the XIPE interesting targets are variable and/or transient sources: • They need to be observed in the interesting state, with typical transition probabilities of once or

few times a year• The interesting state can last from several days to months

The observing program will comprise:

• On target observations (few ks up to few Ms for about 150 observations per year)• Target of Opportunity observations (anticipated and unanticipated)• “Monitoring program”

• Up to few 100s of short pointings per year lasting 300-500 s• To be scheduled in order to minimize the impact on the mission operations• Re-visits to different classes of sources to be scheduled on their typically expected state-

change frequency

Transient/Variable sources: early inspection of the data (<few days) might help to promptly recognize the interesting state of a source, optimizing the observational time and maximizing the science return

• Data availability requirement is 7 days for 80% of the cases• Quick look data need to be available on a shorter timescale

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Data Products

Raw data: Science telemetry plus (preliminary) auxiliary data (e.g., electrical calibration data, orbit prediction files,housekeeping data) that have been produced on board. Science data are currently foreseen (TBD) to be in FITS formatfollowing the CFDP protocol.

Level 0: Raw data removed of any communication artefacts (e.g., headers, duplicated data, etc.) and with applied on-boardcorrections (e.g. corrections of the pixel to pixel gain). Output is a generic events file in binary FITS format including allrecorded events in each GPD detector. The FITS files still contain the full information on the tracks measured by thedetectors, i.e. the photoelectron emission direction is not yet reconstructed.

Level 1: Photon list with the reconstructed photoelectron direction, photon absorption point, energy and time of arrival.Note that a number of calibrations have to be applied to derive this information, including the overall detector gaincalibrations. Photoelectron tracks are no longer available in the FITS file.

Quick look data: A set of preliminarily science data such as light curves, spectra, images, and modulation curves for thecentral source in each observation. The QLA data are produced on board by the XIPE ICU and are downlinked with highpriority, requiring at most 3 kbps TM rate. They provide a quick means to assess the observation output without the need ofprocessing all the observation data.

Level 2: Level 1 data with all corrections applied (such as aspect correction, time calibration, barycentric corrections) andremaining instrument-specific calibrations (such as good-timing information) to level 1 data. Output is cleaned FITS eventfiles for each GPD detector. The data will be organized per exposure/pointing.

Level 3: a set of pre-defined science products (examples: light curves, energy and power spectra, photon lists, andpolarization measurements) extracted for each observation, eventually combining the information derived from allexposures/pointings that constitute an observation.

Level 4: Data containing enhanced, higher level, scientific products derived from Level 3 data, such as catalogs of sources,historical measurements of the flux, combined multi-wavelength spectral energy distribution and polarization. More level 4data products may be defined during the course of the mission.

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Overview (from the SOAD)

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Science Data Center

The XIPE SDC will: • produce all software needed for the processing of the mission data, as well as the daily

processing, analysis, and exploitation of all XIPE data (the software needed for the processing of the raw telemetry into the level 0 data is provided by the IOC)

• package the software in order to facilitate the distribution to the science community• daily process level 0 data into the level 1, 2, 3, and 4 data • check of the X-ray emission status of all XIPE targets with QLA data (“sky monitoring”) • assist SOC in user support for what concerns the data processing, analysis, and exploitation. • organize dedicated workshops for the training of scientists to the usage of the XIPE software

and the manipulation of the mission data products (including training of SOC personnel)

Note on the QLA data: • produced on-board by the ICU, no further processing required on-ground• downlinked through dedicated prioritized virtual channel and sent from MOC to SOC• Include lightcurves in different energy bands, images, spectra, modulation curves• could be used to derive ToO triggers• could be used for instrument health checks by the IOC • could originate circulars/telegrams from the SDC to the science community• could be freely distributed to the science community to maximize their involvement • on best effort basis: if QLA data are lost during transfer, no recovery action foreseen

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Science Data Center

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Slide subtitle

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SGS Timeline

• There is a long-standing expertize and heritage in the European part of the eXTP consortium for the preparation and organization of the SGS (SDCs) of X-ray observatory missions

• We could soon try to exploit ways to make such expertize available to help maximizing the science return of eXTP

• Areas of possible collaboration: – Software development– Archive development and data distribution– Quick look analysis of the WFM data (exploit a continuous sky

monitoring)– QLA and validation of data from all instruments– European «help desk»– ......

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