1. GAIA - BORDEAUX WS 17-18 November 2002 Solar System Working Group 2nd Meeting ----- F. Mignard

2. GAIA - BORDEAUX WS 17-18 November 2002 AGENDA 17/10 09h00 Welcome and administrative matters of the WG, membership F. Mignard 09h30 Status of the GAIA programme M. Perryman 10h00Impacts of the new design : geometry, detection F. Mignard 10h30 Coffee 10h45 Orbit prediction and determination K. Muinonen, J. Virtanen 11h30 Orbit improvementsM. Carpino 12h15 lunch break 14h00 The NEO population model- Observations from space A. Morbidelli 14h30 Simulations of the MPs and NEOs passages with the new designF. Mignard 15h00 Update on a possible ground based network W. Thuillot 15h30 Design of an automatic instrument: the ARAGO project M. Boer 16h00 The asteroid data base by 2010 E. Zappala 16h30coffee 17h00 Simulation of images of asteroids by GAIA A. Dell'Oro 18h00Signal produced by gaia from asteroids D. Hestroffer (scattering, shape, photocenter shift) 18h30Interactions with the simulation group all

3. GAIA - BORDEAUX WS 17-18 November 2002 AGENDA 18/10 9h00 Taxonomy with the photometric data : status E. Dotto 9h30 Asteroids radial velocity E. Dotto 10h15 The data base for GAIA E. Zappala 10h45 Coffee 11h00 Masses of asteroides from ground based observations. M. Rapaport The present situation. Perspectives. 11h45 Statistics of close approaches in 2011-2016. F. Mignard 12h15 lunch break 14h00 Conclusions and actions, next meeting 16h00 End of the Meeting

4. GAIA - BORDEAUX WS 17-18 November 2002 The Solar System Science with GAIA The Solar System Working Group

5. GAIA - BORDEAUX WS 17-18 November 2002 Science Goals Systematic survey down to 20 mag ~ 5x10 5 objects Main belt NEOs Orbits : virtually all object observed - x30 better than now Masses from close encounters ~ 100 masses expected Diameter for over 1000 asteroids : shape, density Photometric data in several bands : albedo, taxonomic classification Space distribution vs. physical properties Perihelion precession for 300 planets

6. GAIA - BORDEAUX WS 17-18 November 2002 Objectives of the task Assess observability of : –minor planets, NEOs, satellite, comets, KBO Set the constraints on the CCDs for the best detection of moving sources Determine the algorithms for the orbit reconstruction (known or new objects) Assess the requirements on photometry for the best science return Assess the needs of and provide solar system ephemeris Provide recommendations for the quick alert mode Investigate the organisation of follow-up observations

7. GAIA - BORDEAUX WS 17-18 November 2002 M. Carpino A. Cellino A. del'Oro E. Dotto D. Hestroffer E. Hoeg S. Klioner F. Mignard K. Muinonen M. Rapaport P. Tanga W. Thuillot E. Zappala C. Bailer-Jones P. Bendjoya J. Berthier F. Colas A. Doressoundiram W. Evans C. Fabricius P. Hjorth J. Kovalevsky P. Kroll C.I. Lagerkvist R. Michelsen A. Morbidelli V. Vansevivius J. Virtanen S. Wolff Core members Associates Membership

8. GAIA - BORDEAUX WS 17-18 November 2002 Activities Tasks identified Leader - Asteroid size and shape A. Cellino - Simulation and detectionF. Mignard - Orbit determination K. Muinonen - Surface propertiesP. Tanga - Photometry & TaxonomyE. Dotto - Data baseE. Zappala - Mass determination D. Hestroffer - Ground based follow-upW. Thuillot

9. GAIA - BORDEAUX WS 17-18 November 2002 Review of Actions (Feb 02) Provide a reference orbit for GAIA about L2 (FM) Investigate the possibility to obtain radial velocities (ED) Short note on the Monte Carlo method for orbits (KM) Algorithms for the orbit determination with GAIA data (KM, MC,DH) Investigate the propagation of orbit uncertainty to positions (MC) Outline of a global solution for mass determination (FM, DH) Investigate the photocenter offset vs. scattering model (AC) State of the art in the knowledge of asteroid masses (MR) How many objects and orbits by 2010 ? (EZ) Web pages on-line (FM) Discussion area and common storage zone (PT)

10. GAIA - BORDEAUX WS 17-18 November 2002 Relevance of the new design for Solar System

11. GAIA - BORDEAUX WS 17-18 November 2002 ASTRO-1 secondary mirror Astro-2 Primary mirror Astro-1 Primary mirror Basic angle monitoring GAIA : Optical system ASTRO focal plane reflectors)

12. GAIA - BORDEAUX WS 17-18 November 2002 Parameters of the main optics Aperture 1.4 x 0.5 m 2 Aperture 1.4 x 0.5 m 2 Focal length 47 m Focal length 47 m Scale 1 mas = 0.2 µm Scale 1 mas = 0.2 µm Basic angle106° Basic angle106° Spin period6 h Spin period6 h Astro Fi eld of view Astro Fi eld of view 0.66 x 0.66 deg 2 Extended0.92 x 0.66 deg 2 Extended0.92 x 0.66 deg 2

13. GAIA - BORDEAUX WS 17-18 November 2002 Astro Focal plane ~ 750 mm, 0.92 deg 600 mm 0.74 deg ASM2 ASM1 AF1-11BBP Astro Field Cell size : 49 x 60 mm 2 Cell size : 49 x 60 mm 2 CCD size : 45 x 59 mm 2 CCD size : 45 x 59 mm 2 4.5 k x 2 k 4.5 k x 2 k Pixel size 10 x 30 µm 2 Pixel size 10 x 30 µm 2 = 44 x 133 mas 2 = 44 x 133 mas 2 TDI : 0.735 ms TDI : 0.735 ms Airy (along) 103 mas Airy (along) 103 mas Integration time : 3.3 s Integration time : 3.3 s For ASM : 1.9 s For ASM : 1.9 s FOV 2 FOV 1

14. GAIA - BORDEAUX WS 17-18 November 2002 Photo and spectro telescope Focal length 2.1 m Aperture0.5 x 0.5 m 2 Airy spot~ 300 mas Field of view2° x 4.8 ° Unvignetted2° x 3.2 ° Scale10 µm = 1"

15. GAIA - BORDEAUX WS 17-18 November 2002 MBP and Spectro Fields 1.6° 60 mm 2° = 120s = 74 mm 1.6° 60 mm MBP2 1.6° 60 mm RVS RVSM MBPSM MBP1 CCDs MBP : 336 x 3932 pxs RVS : 1100 x 3932 pxs Pixel size 10 x 15 µm 2 10 x 15 µm 2 1 x 1.5 arcsec 2 1 x 1.5 arcsec 2 Integration time RVSM ~ 3 x 5.5s MBPSM : 5.5 s Resolution R ~ 10000 = 0.4 Å/pixel V =19%

16. GAIA - BORDEAUX WS 17-18 November 2002 Detection of moving objects

17. GAIA - BORDEAUX WS 17-18 November 2002 Detection and recognition Solar system objects are moving relative to the stars Internal detection from motion: field crossing ~ 30 s, Observations in the 2 astro FOVs and in the spectro FOV – NEO~ 50-100 mas/s – Main belt~ 10 mas/s – Trojan~ 5 mas/s – Kuiper belt~ 1 mas/s

18. GAIA - BORDEAUX WS 17-18 November 2002 Astro and Spectro Focal planes ~ 750 mm, 0.92 deg 600 mm 0.74 deg ASM2 ASM1 AF1-11BBP FOV 2 FOV 1 1.6° 60 mm 2° = 120s = 74 mm 1.6° 60 mm MBP2 1.6° 60 mm RVS RVSM MBPSM MBP1 V =19%

19. GAIA - BORDEAUX WS 17-18 November 2002 Detection-I AiryPixelIntegration masmas s ASM100401.9 AF1100403.3 RVSM30010005.5*3 MBPSM30010005.5

20. GAIA - BORDEAUX WS 17-18 November 2002 Detection II Signature : relative motion of the image wrt TDI'ed image Measure : comparison of abscissa in different CCDs Average alon-scan speed : –10 mas/s main-belt –30 mas/s neo ASM1ASM1 ASM2ASM2 AF1AF1 s mas pixels MBNEOMBNEO ASM1  AF14.5451351.13.3 ASM2  AF12.626 780.72.1 AF1  AF11333301000 824 RVSM1  RVSM3121203600.120.4

21. GAIA - BORDEAUX WS 17-18 November 2002 Detection III Motion between Prec and Foll FOV No direct comparison of position But shift wrt to the stars  shift in crossing time 106° ~ 6000 s MBNEO  ~60180"  t ~ 1s3s

22. GAIA - BORDEAUX WS 17-18 November 2002 Detection IV 0.7° ~ 3s = 180 " 0.25° max t t+ 6000 s

23. GAIA - BORDEAUX WS 17-18 November 2002 Simulations and tools available

24. GAIA - BORDEAUX WS 17-18 November 2002 Simulation for the Solar System Goal : to provide realistic sequences of observations of moving sources Method : Computing the crossing time in the 3 FOVs of minor planets Crossing over 5 years of the scanning law and several 10 4 asteroids (main belt, neos) Output : for each object –t 1, t 2, … t n : crossing times –v 1, v 2, … v n : crossing speed ( along scan and transverse) –Apparent magnitude

25. GAIA - BORDEAUX WS 17-18 November 2002 Structure of the output file 1 Ceres 310 2 2 0 1 -1 0 2 2 15.5200 15.7708 16.0217 16.0731 16.1475 16.2725 16.5234 36.5252 8.0 8.0 8.0 8.0 8.0 8.0 8.0 7.6 21.45 21.43 21.40 21.40 21.37 21.37 21.34 17.87 2.30 2.20 2.11 2.11 2.01 2.01 1.91 -3.05 6.05 6.03 6.01 6.01 5.99 5.99 5.97 -1.52 Planete ID, N_obs Fields (0 : spectro, 1: astro leading, -1 : astro trailing, 2 : MBP) Crossing time (days) Apparent magnitude Phase angle in deg. Inertial speed along scan in mas/s Inertial speed cross scan in mas/s

26. GAIA - BORDEAUX WS 17-18 November 2002 Other tools Scanning law of GAIA as a callable subroutine – call scanning(XMJD, XSI,XKK,ETAZ, XLSUN, PSI, TETA,PSIP,TETAP, SUN, EPS) ! input ! ! xmjd : date in modified julian days ! xsi : sun aspect angle (50 deg) ! xkk : precession frequency (5.25 rd/yr) ! etaz : initial phase ! ! output ! ! xlsun: longitude of the sun in degrees ! psi : ascending node/sun of the scanning circle in deg ! teta : inclination of the scanning circle in deg ! psip : dpsi/dt in "/s ! tetap : dteta/dt in "/s ! sun : heliotropic abscissa of the node ! eps : latitude of the sun /scanning circle (pi/2-xi)

27. GAIA - BORDEAUX WS 17-18 November 2002 Other tools A realistic orbit of Gaia about the L2 point (file or subroutine) –Lissajous orbit with 6 - 7 years quasi-period Motion of the barycenter wrt the Sun –Surbroutine with an accuracy of 1000 km

28. GAIA - BORDEAUX WS 17-18 November 2002 Overall Statistics

29. GAIA - BORDEAUX WS 17-18 November 2002 Number of observations

30. GAIA - BORDEAUX WS 17-18 November 2002 Number of Epochs

31. GAIA - BORDEAUX WS 17-18 November 2002 Phases of minor planets with GAIA Statistics on the first 20 000 planets

32. GAIA - BORDEAUX WS 17-18 November 2002 Solar elongation of minor planets Statistics on the first 20 000 planets

33. GAIA - BORDEAUX WS 17-18 November 2002 Apparent magnitude Statistics on the first 20 000 planets

34. GAIA - BORDEAUX WS 17-18 November 2002 Apparent Magnitudes V = H +  m

35. GAIA - BORDEAUX WS 17-18 November 2002 Along and across-scan proper speed MB NEOs

36. GAIA - BORDEAUX WS 17-18 November 2002 Distance to Sun and Earth MB

37. GAIA - BORDEAUX WS 17-18 November 2002 How many Close Approaches ?

38. GAIA - BORDEAUX WS 17-18 November 2002 Close approach : impulse approximation Perturbed motion of a minor planet m  mD  V  M sol kmuakm/smas 10 -10~ 5000.1340 0.05380 10 -11~ 2000.134 0.0538 V 

39. GAIA - BORDEAUX WS 17-18 November 2002 Close approaches 2010.5 - 2016 List of close approaches between –the first 500 minors planets and 20 000 targets Criteria used for an effective close approach –distance –relative speed –angular deflection –impulse change of orbital elements Ouptut : – each close approach (date, geometry, efficiency) – global statistics per deflector

40. GAIA - BORDEAUX WS 17-18 November 2002 d min < 0.2 0.1 0.05 0.02 0.01 au 1 Ceres 356 82 14 3 0 2 Pallas 181 46 9 1 1 3 Juno 531 125 23 3 0 4 Vesta 597 159 37 5 2 5 Astraea 577 141 41 5 1 6 Hebe 512 134 34 4 2 7 Iris 556 136 34 1 0 8 Flora 626 155 35 6 1 9 Metis 597 141 38 8 2 10 Hygiea 238 56 14 3 2 11 Parthenope 603 153 43 6 2 12 Victoria 532 129 36 4 2 13 Egeria 287 86 12 1 0 14 Irene 408 108 22 5 2 15 Eunomia 473 115 25 1 0 Number of closest approaches < d min

41. GAIA - BORDEAUX WS 17-18 November 2002 Statistics

42. GAIA - BORDEAUX WS 17-18 November 2002 Number of deflections >  lim  > 1 5 20 100 mas 1 Ceres 8738 4828 1518 163 2 Pallas 275 18 1 0 3 Juno 162 6 0 0 4 Vesta 5772 1575 314 30 5 Astraea 41 6 0 0 6 Hebe 66 9 0 0 7 Iris 382 51 7 1 8 Flora 188 22 2 2 9 Metis 3369 773 144 16 10 Hygiea 3675 901 193 26 11 Parthenope 377 48 8 0 12 Victoria 34 8 2 0 13 Egeria 93 5 2 0 14 Irene 1874 195 24 3 15 Eunomia 377 27 6 0 N > 5 305 120 40 11

43. GAIA - BORDEAUX WS 17-18 November 2002 Actions for the next six months

44. GAIA - BORDEAUX WS 17-18 November 2002

45. Actions (Oct 02) Pending from the last meeting Outline of a global solution for mass determination (MR, FM, DH) Web pages on-line (FM, PT) –available documents, presentations... New actions Initial error model for the astro observations of moving objects (FM) Simulated observations in the astro fields over short timespan (FM) Contact with C. Jordi for the photometric band (ED) Algorithms for detection for moving objects (SW, FM, PH, EH) Contact with IAU WG on GB astrometry (WT) Determination of physical parameters from photometry (EZ) Observability of planets and satellites (PT) Add planets in the simulation file (FM)

46. GAIA - BORDEAUX WS 17-18 November 2002 Actions (Oct 02) New actions (ctd) Radial velocities in the simulation file (FM) List of minor planets and pieces of software for Sim WG (AM) Observations of very faint objects with input catalogue () GB observations vs. GAIA for orbit improvement (MC) Non gravitational forces (AM,....)

47. GAIA - BORDEAUX WS 17-18 November 2002 D : diameter - H : abs. mag. -  : angular diameter - V : apparent mag. Some useful numbers Albedo = 0.05