GAIA SWG April DMS/PS-WG meeting1 SWG & DMS/PS simulations C. Babusiaux, X. Luri, E. Masana, F. Arenou

GAIA SWG April DMS/PS-WG meeting2 SWG Kick-Off meeting – Cambridge March 2002 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 GOALS

GAIA SWG April DMS/PS-WG meeting3 Community involvement: task list

GAIA SWG April DMS/PS-WG meeting4

GAIA SWG April DMS/PS-WG meeting5 Organisation of the work

GAIA SWG April DMS/PS-WG meeting6 Proposed structure of GAIA simulator Common toolbox GASSGIBIS Pixel-level simulations Telemetry simulations Cater for the “official” mission simulation needs Mission design ( ) Preparation of data reduction (2002  ) Preparation of scientific exploitation (2002  ) Specific simulations for scientific purposes

GAIA SWG April DMS/PS-WG meeting7 Proposed organisation of development CORE TEAM Coordination Maintenance & development of common toolbox Ensure that mission needs are covered GIBIS TEAM Simulated images GASS TEAM Simulated Telemetry Specific simulations

GAIA SWG April DMS/PS-WG meeting8 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

GAIA SWG April DMS/PS-WG meeting9 Common tool box & data generators

GAIA SWG April DMS/PS-WG meeting10 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

GAIA SWG April DMS/PS-WG meeting11 Status

GAIA SWG April DMS/PS-WG meeting12 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,...)

GAIA SWG April DMS/PS-WG meeting13 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.

GAIA SWG April DMS/PS-WG meeting14 Reference Universe Snap-shot (t 1,t 2 ) GAIA DB Objects Background Scan law Attitude Efemeris etc. Instruments Noise etc. Data processes: Reduction & calibration Scientific exploitation etc. GASS activities Telemetry Raw data Apparent Sky Housekeeping data Satellite & instrument model

GAIA SWG April DMS/PS-WG meeting15 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 sequence stars (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).

GAIA SWG April DMS/PS-WG meeting16 Gaia Image and Basic Instrument Simulator 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

GAIA SWG April DMS/PS-WG meeting17 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

GAIA SWG April DMS/PS-WG meeting18 GIBIS Status Development UML design, Java core, Iraf Image simulation xWeb page Instrument All instruments, Gaia2, Detection, PSF, Noise xScanning law, photometry, selection, tracking, saturation, linearity, CTE, aging, RVS Universe Single, multiple stars, clusters, galaxies, HST image xTime variation, cosmic-rays, solar-system objects

GAIA SWG April DMS/PS-WG meeting19 Priorities & schedule

GAIA SWG April DMS/PS-WG meeting Use of simulations for mission/instrument design GAIA design is frozen Short term mission schedule Use of simulations for data analysis preparation GDAAS 2005 Technology development

GAIA SWG April DMS/PS-WG meeting21 Long term mission schedule Use of simulations for data analysis preparation Launch! Observations Use of simulations for scientific exploitation preparation Analysis Design, build, test Catalogue!

GAIA SWG April DMS/PS-WG meeting22 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)

GAIA SWG April DMS/PS-WG meeting23 SWG priorities – short term ( ) 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 oIngestion oQuick-look & initial classification oCore processing (GIS) oSpectro & photometry processing  Query system & visualisation tools

GAIA SWG April DMS/PS-WG meeting24 SWG priorities – short term ( ) 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?

GAIA SWG April DMS/PS-WG meeting25 SWG priorities – long term (2005  ) I Data analysis  Data processing (pipeline) development & optimisation oIngestion oQuick-look & initial classification oCore processing (GIS) oSpectro & photometry processing  Shell processing  Refined classification of objects  Refine and expand query system & visualisation tools  Interoperability with other large astronomical databases

GAIA SWG April DMS/PS-WG meeting26 Scientific exploitation  Produce simulated data allowing teams to prepare the exploitation of GAIA data (through GAIA DB?). SWG priorities – long term (2005  ) II

GAIA SWG April DMS/PS-WG meeting27 SWG initial schedule & milestones Immediate coordination activities  Complete task list with names: April 2002  Ref. document: May 2002 including schedule for 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: ??

GAIA SWG April DMS/PS-WG meeting28 DMS/PS simulations

GAIA SWG April DMS/PS-WG meeting29 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. ClassExtended ClassMethod AstroObjectSingle Star Multiple Star NEO Quasar... getPosition(time) An unique Method with different implementations (one for object type)

GAIA SWG April DMS/PS-WG meeting30 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.

GAIA SWG April DMS/PS-WG meeting31 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)

GAIA SWG April DMS/PS-WG meeting32 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

GAIA SWG April DMS/PS-WG meeting33 II) Observations Spectroscopy – Radial velocity Photometry (if eclipsing) – Light curve – Light-time travel R CMa, eclipsing binary with a P=100yr companion 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

GAIA SWG April DMS/PS-WG meeting34 Optimisations Needed More realistic distribution of DMS/PS/BD Evolved companions Peculiar objects (contact binaries) Variable companions

GAIA SWG April DMS/PS-WG meeting35

GAIA SWG April DMS/PS-WG meeting36 Backup slides

GAIA SWG April DMS/PS-WG meeting37 Instrument models

GAIA SWG April DMS/PS-WG meeting38 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

GAIA SWG April DMS/PS-WG meeting39 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

GAIA SWG April DMS/PS-WG meeting40 Java Object-oriented Really portable Allows a fast development Not too fast Not yet popular in the astronomical community No numerical libraries available

GAIA SWG April DMS/PS-WG meeting41 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. Programming languages

GAIA SWG April DMS/PS-WG meeting42 CVS 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.

GAIA SWG April DMS/PS-WG meeting43 CVS REPOSITORY Reference version of source files CVS server CVS client Local version Local version Local version Local version