1. KBO Workshop, DPS 2003 - Stellar occultations are diffracting phenomena - A powerful tool to accede to invisible small KBO - First results of the Pic du Midi campaign - Prospective projects Roques, F., (1), Doressoundiram A. (1), Moncuquet M. (1), Chevreton M. (1), Colas, F. (2), Lecacheux, J.(1), Auvergne, M.(1) GP Tozzi (3), O. Hainault (4) (1) LESIA, Observatoire de Paris, 92195 Meudon (France) (2) IMCCE, Observatoire de Paris, 92195 Meudon (France) (3) Oss. Astrofisico di Arcetri, Firenze (Italy) (4) European Southern Observatory

2. KBO Workshop, DPS 2003 The shadow of the Kuiper Belt Objects Roques and Moncuquet, 2000 Circular 1km KBO Elliptical 1km KBO

3. KBO Workshop, DPS 2003 Occultation profiles for different stars

4. KBO Workshop, DPS 2003 Amplitude variation of the stellar flux R * < Fresnel scale = √ ( D/2) Roques and Moncuquet, 2000

5. KBO Workshop, DPS 2003 Amplitude variation of the stellar fux R * > Fresnel scale Roques and Moncuquet, 2000

6. KBO Workshop, DPS 2003 The detection of diffracting occultations needs High speed photometric observations The noise (scintillation) limits the possibility to detect an occultation event The simulations => depth of the occultation profiles A 4  deep event is detectable  => detectable KBO 0.01=> 120 meters KBO 0.001=> 40 meters KBO The velocity of the KBO in the sky plane toward the opposition : 25 km/sec => Fast photometry (20 hz) is necessary

7. KBO Workshop, DPS 2003 Occultations rates TAOS T4M T8M space

8. KBO Workshop, DPS 2003 Estimated Occultation Rates (stellar size = 0.003 mas) Event depth rate/night q=3 q=4 1. 0.1 0.01 0.001 1. 0.1 0.01 10. P = 0.02 (80 m) P = 0.06 (150m)

9. KBO Workshop, DPS 2003 Telescopes sizes and constraint on q The noise is due to scintillation:  = S 0.d -2/3.X 3/2.e -h/H0.(2  ) -1/2 T2M :  =0.02 T4M :  =0.01 T8M :  =0.001

10. KBO Workshop, DPS 2003 Observations PIC 2000-2003 2 telescopes: T-2m and T-1m Multi-objects photometers: - a target star - a comparison star - sky Ecliptic latitude = 0.2 °- r * =50m 20 Hz 09/2000(7 nights) +03/2003 (7 nights) Method : cumulative observations homogeneous data processing=>4-  events comparison with estimations

11. KBO Workshop, DPS 2003 Observations PIC 2000 T2m data 15 hours of data with  better than 0.02 (T-2m) and  = 0.027 (T-1m) Stellar flux  (5 mn )

12. KBO Workshop, DPS 2003 Observations PIC 2003 12 hours of data with  better than 0.02 (T-2m)

13. KBO Workshop, DPS 2003 Observations PIC 2000-2003 27 hours of observations and 4-  level of detection => Estimation of occultation rate : 0.4 (q = 3) 2 (q = 4) 4 (q = 4.5) 0 detection

14. KBO Workshop, DPS 2003 Observations PIC 2000-2003 A potential event (3-  ) compatible with a 150 meter KBO q = 3 q = 4 log(depth) log(rate)

15. KBO Workshop, DPS 2003 COROT Launch : 2005 EDDINGTON (one month) : hundreds of KBO, 15 m - 5 km

16. KBO Workshop, DPS 2003 Prospective -chromaticity-  = 0.01 (4.m telescope) - r = 100 m = 0.4  m = 1.2  m Information on the Fresnal scale, then, on the distance of the KBO

17. KBO Workshop, DPS 2003 Prospective : 8 meters telescope - space  = 0.001 (8-m telescope) - r = 40m Information on the size and distance of the KBO Fast phtometry 20-100 Hz needed!

18. KBO Workshop, DPS 2003 Prospective Distants objects : Oort cloud A 4 km Oort cloud object at 10 4 AU

19. KBO Workshop, DPS 2003 Future projects Campaign on the TBL telescopes Larges telescopes => pb : fast photometry Technical data : guiding cameras ESO-VLT Space : Corot, Eddington, dedicated instrument

20. KBO Workshop, DPS 2003 Conclusions Stellar occultations give a zoom on planétésimals :kilometer and sub- kilometer Kuiper Belt objects Diffracting occultations are accessible from ground-based telescopes Campaign on Pic du Midi 2000-2003 : zero 4  event on 27 h => first constraint on q one potentiel event (150 meters KBO) Large Telescopes + fast photometry (20 hz) =>??? Space : high precision photometry missions (Corot - Eddington) Dedicated instrument/mission

21. KBO Workshop, DPS 2003 Occultations rate and telescope sensitivity log(depth ) log(rate/night) q=3 q=4