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SWG & DMS/PS simulations

SWG & DMS/PS simulations. C. Babusiaux, X. Luri, E. Masana, F. Arenou. SWG Kick-Off meeting – Cambridge 11-12 March 2002. GOALS. Involve the GAIA community in the activities of the SWG Organise the work and set up a coordination strategy Define priorities and needs for simulations

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SWG & DMS/PS simulations

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  1. SWG & DMS/PS simulations C. Babusiaux, X. Luri, E. Masana, F. Arenou DMS/PS-WG meeting

  2. SWG Kick-Off meeting – Cambridge 11-12 March 2002 GOALS • Involve the GAIA community in the activities of the SWG • Organise the work and set up a coordination strategy • Define priorities and needs for simulations • Define a schedule for simulation activities DMS/PS-WG meeting

  3. Community involvement: task list DMS/PS-WG meeting

  4. DMS/PS-WG meeting

  5. Organisation of the work DMS/PS-WG meeting

  6. Common toolbox Proposed structure of GAIA simulator GASS GIBIS Telemetry simulations Pixel-level simulations Cater for the “official” mission simulation needs Specific simulations for scientific purposes • Mission design (2002-2005) • Preparation of data reduction (2002 ) • Preparation of scientific exploitation (2002 ) DMS/PS-WG meeting

  7. CORE TEAM • Coordination • Maintenance & development of common toolbox • Ensure that mission needs are covered GASS TEAM GIBIS TEAM • Simulated images • Simulated Telemetry Proposed organisation of development Specific simulations DMS/PS-WG meeting

  8. Working tools • UML (Unified Modelling Language) • Design tool to build software systems • Java • Object oriented, portable language • CVS (Concurrent Versions System) • Development tool for maintenance of source code • See http://www.cvshome.org/ DMS/PS-WG meeting

  9. Common tool box & data generators DMS/PS-WG meeting

  10. Integration of contributions • Contributions provided by the community • Integration into the system is a responsibility of the Core Team • A programming interface, conventions & procedures will be developed • Documentation should be provided/developed in parallel with the code DMS/PS-WG meeting

  11. Status DMS/PS-WG meeting

  12. The GAIA System Simulator (GASS) The aim of the GASS is to simulate GAIA telemetry (observation + satellite HK data) using models of the objects and instruments. • The GASS will provide realistic data for: • Predictions to be used for mission design. • Filling of test databases (e.g. the GDAAS database) • Testing of algorithms (e.g. cross-matching, telemetry compression,..) and reduction software (e.g. core processing). • Evaluation of mission performances, in particular for some peculiar objects (binary stars, NEO’s, extrasolar planets,...) DMS/PS-WG meeting

  13. GASS - Simulation Process • Simulation of the objects visible along the scan of the instruments. For each object and epoch the program simulates position, kinematics and photometry. This step includes an Universe model and the scanning law and orbitals parameters of the satellite. • Transformation from sky coordinates to instrument coordinates. This step includes the geometry and the optics of the instrument, together with the configuration of the field of view (FOV). • Simulation of the observational process according to the instrumental parameters: detection, acquisition of data and telemetry. This step includes a model of the observational process. DMS/PS-WG meeting

  14. Reference Apparent Raw Snap - shot Telemetry Universe Sky data (t ,t ) 1 2 GAIA Satellite & instrument DB model Data processes: Reduction & calibration Scientific exploitation etc. Background Objects Scan law Instruments Attitude Noise Efemeris etc. etc. Housekeeping data GASS activities DMS/PS-WG meeting

  15. GASS - Current status • Reference Universe: • Sun & Earth: the simulator implements a very simple algorithm to calculate ephemeris for the Sun and Earth. No other solar system bodies are yet considered. • Galaxy: the Galaxy model from Torra et al. (1999; Baltic Astronomy 8, 171) is implemented. Only main sequencestars (single and binary) are included. • Satellite model: • Attitude model: nominal scan law (L.Lindegren) and (simplified) satellite orbit implemented. • Geometric model of the Astro Focal Plane. • Instrument model: • Only Astro1 and Astro2 instruments are considered. • A simple detection process is simulated in order to obtain the detection parameters for each object. • A bi-dimensional realistic PSF has been implemented (but does not include chromaticity or focal plane position effects). DMS/PS-WG meeting

  16. Test the on-board algorithms Detection, Confirmation, Selection Compression Provide statistical results for GASS Focal plane optimisation studies Patches and samples Impact of CCD degradataion on final accuracy Reduction studies Image combining Calibration GaiaImage and Basic Instrument Simulator DMS/PS-WG meeting

  17. GIBIS Simulator • Sources • All : ponctual, extended, fast moving objects • Statistical models • Special configurations • Time variation (variability, astrometry) • Observed images (HST) • Instrument • All transits (scanning law) • All fields • On-board detection, selection, tracking • CCD details (noise,CTI, degradation…) • Modular & easy to use DMS/PS-WG meeting

  18. GIBIS Status • Development • UML design, Java core, Iraf Image simulation • Web page • Instrument • All instruments, Gaia2, Detection, PSF, Noise • Scanning law, photometry, selection, tracking, saturation, linearity, CTE, aging, RVS • Universe • Single, multiple stars, clusters, galaxies, HST image • Time variation, cosmic-rays, solar-system objects DMS/PS-WG meeting

  19. Priorities & schedule DMS/PS-WG meeting

  20. Short term mission schedule 2001 2002 2003 2004 2005 Use of simulations for data analysis preparation GDAAS Use of simulations for mission/instrument design GAIA design is frozen Technology development DMS/PS-WG meeting

  21. Long term mission schedule 2005 2010 2020 2015 Use of simulations for data analysis preparation Use of simulations for scientific exploitation preparation Design, build, test Launch! Observations Analysis Catalogue! DMS/PS-WG meeting

  22. SWG priorities – immediate (2-3 months) • Set up the Core Team: members! You are invited to join • Estimate manpower available and match it to needs/deadlines • Coordination • Packages & tasks, responsabilities • Reference document to organise work • Compilation of conventions, constants & reference terms (use/complement GAIA-BCN-0??) • Merging of GIBIS-GASS • Take into account the new design of GAIA • Provide acces to simulated data (web page?) • Lists of objects • Images • Telemetry files • GDAAS access (feasibility? DAWG) DMS/PS-WG meeting

  23. SWG priorities – short term (2002-2005) I • Mission design • Detailed testing of the capabilities of the revised GAIA design • Simulations to complete Spectro design and evaluate its performance • Telemetry & compression: final budget and trade-offs • On-board data handling design • Data analysis • Database design optimisation • Data processing (pipeline) design • Ingestion • Quick-look & initial classification • Core processing (GIS) • Spectro & photometry processing • Query system & visualisation tools DMS/PS-WG meeting

  24. SWG priorities – short term (2002-2005) II • Scientific exploitation • Estimation of GAIA performance for critical types of objects Simulations for the development of specific algorithms for data reduction. • Other scientific aspects? DMS/PS-WG meeting

  25. SWG priorities – long term (2005 ) I • Data analysis • Data processing (pipeline) development & optimisation • Ingestion • Quick-look & initial classification • Core processing (GIS) • Spectro & photometry processing • Shell processing • Refined classification of objects • Refine and expand query system & visualisation tools • Interoperability with other large astronomical databases DMS/PS-WG meeting

  26. SWG priorities – long term (2005 ) II • Scientific exploitation • Produce simulated data allowing teams to prepare the exploitation of GAIA data (through GAIA DB?). DMS/PS-WG meeting

  27. SWG initial schedule & milestones • Immediate coordination activities • Complete task list with names: April 2002 • Ref. document: May 2002 including schedule for 2002-2005 activities related to mission design • Complete the merging of GIBIS & GASS: June 2002 • Integration activities • Initial version of web page access to simulations: May 2002 • Agreed schema for integration of contributions: ?? • 1st version of common tool box: ?? • Programming interface: ?? DMS/PS-WG meeting

  28. DMS/PS simulations DMS/PS-WG meeting

  29. Object simulation: unification of the process • The AstroObjects that form the ObservingList contain all the methods needed to generate observations. This allows the unification of the process even for very different types of objects. An unique Method with different implementations (one for object type) DMS/PS-WG meeting

  30. Object simulation: SnapShots • The simulation of objects is carried out through the SnapShots. • A SnapShot is a list of candidate objects (of one or more types) to be observed by an instrument between two times (time1 and time2). • Example: the SnapShot for the galaxy model is formed by the objects (single stars, binary stars,...) generated into the HTM triangles crossed by the FOV between time1 and time2. DMS/PS-WG meeting

  31. Crude simulation of Double Star / Planets • Why ? • Initially, to complexify the sky model in GDASS • Now included in GASS/GIBIS • Need to be complexified: to be used as a template • Two Java classes • Generation (dms_simu) • Use (dms_orbit) DMS/PS-WG meeting

  32. I) Generation • A call each time a star is created • Randomly choose • Number of companions • Masses, down to EP • Orbital elements • Just needs as input: • The absolute magnitude of the primary • Optionally colour and mass of primary • Simplistic assumptions • Mostly based on Duquesnoy&Mayor 1991 for all stars • Main-sequence assumed • … needs something more realistic at a later stage DMS/PS-WG meeting

  33. II) Observations • Computes the orbital effect at the given epoch • getPosition(t) • Simplistic hypothesis • No interaction between companions • No limb darkening, no mass transfer, etc… • Astrometry • Alpha, delta • Distance • Spectroscopy • Radial velocity • Photometry (if eclipsing) • Light curve • Light-time travel R CMa, eclipsing binary with a P=100yr companion DMS/PS-WG meeting

  34. More realistic distribution of DMS/PS/BD Evolved companions Peculiar objects (contact binaries) Variable companions Optimisations Needed DMS/PS-WG meeting

  35. DMS/PS-WG meeting

  36. Backup slides DMS/PS-WG meeting

  37. Instrument models DMS/PS-WG meeting

  38. UML The design and building of the GAIA simulator is a challenging task: • Need for requirements & specifications to guide the development • Many teams involved • Management and coordination required • Need to organise & control the source code • Standarisation of tools, methods and interfaces is key for success DMS/PS-WG meeting

  39. The Unified Modelling Language (UML) was developed as a tool for the design and management of software projects: • Allows to specify, visualize and document a system under development • Facilitates the collaboration between teams • Allows a modular, iterative and incremental development • Provides a common description tool, avoiding ambiguities in the design of the system DMS/PS-WG meeting

  40. Java • Object-oriented • Really portable • Allows a fast development • Not too fast • Not yet popular in the astronomical • community • No numerical libraries available DMS/PS-WG meeting

  41. Programming languages • We propose to build the system around a Java core. • It is possible, with proper planning, to integrate algorithms & modules written in any programming language. • However, this integration should be carefully planned and carried on to ensure portability and to avoid a heavy load on the team in charge of the integration. DMS/PS-WG meeting

  42. CVS http://www.cvshome.org/ CVS is a version control system used to record the history of the project source files It allows a team of developers to simultaneously work in the same set of source code files while avoiding the overwritting or incompatibility of each other updates. CVS solves this problem by insulating the different developers from each other. Every developer works in his own directory, and CVS merges the work when each developer is done. At the same time, it ensures that each developer has the most recent version of the files. DMS/PS-WG meeting

  43. CVS REPOSITORY Reference version of source files Local version Local version Local version Local version CVS server CVS client CVS client CVS client CVS client DMS/PS-WG meeting

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