Inversion Model Summary of Asteroidal Occultations

1. Inversion Model Summary of Asteroidal Occultations Historical Model Fits Multi - Model Fits Multi-Year Model Fits Brad Timerson, IOTA Annual Meeting October, 2015

2. Historical Model Fits Do present modeling techniques fit old events? Multi - Model Fits Does one model fit better than another? Multi-Year Model Fits How do models fit the same asteroid over time?

3. Introduction to Inversion Models “The knowledge of basic physical characteristics of asteroids – the spin rate, the spin axis orientation, the shape, the size, the mass, the spectral type, etc. – is important for understanding the history and the current state of the asteroid population. Apart from a few asteroids directly imaged by spacecraft, our knowledge about asteroid physical properties is based on remote sensing techniques. And from all these techniques, time-resolved photometry is by far the most important source of information because it is in principle available for all known asteroids. The lightcurve inversion method developed by Kaasalainen & Torppa (2001) and Kaasalainen et al. (2001) is a powerful tool for deriving asteroid shapes and spins from their lightcurves observed over several apparitions. So far, the lightcurve inversion method has led to models of about one hundred asteroids. The models have been published in several papers (Kaasalainen et al. 2002b, 2004; Torppa et al. 2003; Durech et al. 2009, for example). “ “Most DAMIT models were derived from photometric data by the lightcurve inversion method. Some of them have been further refined or scaled using adaptive optics images, infrared observations, or occultation data.” (J. Durech, V. Sidorin, and M. Kaasalainen, 2010)

4. Historical Model Fits Do present modeling techniques fit old events? Inversion Model fits – 1979 to present

5. 11 December 1979 – 3 Juno

6. 29 May 1983 – 2 Pallas

7. 21 January 1991 – 230 Athamantis

8. 10 December 1993 – 85 Io

9. 21 March 1998 – 39 Laetitia

10. 2 July 1999 – 41 Daphne

11. 10 February 2004 – 34 Circe

12. 12 December 2004 – 85 Io

13. 13 August 2005 – 89 Julia

14. 17 May 2005 – 54 Alexandra

15. 10 January 2007 – 44 Nysa

16. 14 January 2007 – 26 Freia

17. 18 February 2007 – 55 Pandora

18. 6 June 2008 – 5 Astraea

19. 4 June 2010 – 80 Sappho

20. 21 August 2010 – 16 Psyche

21. 26 January 2011 – 11 Parthenope

22. 9 March 2011 – 72 Feronia

23. 22 April 2011 – 17 Thetis

24. Multi - Model Fits For those asteroids having more than one model, does one model fit better than another?

25. 29 October 2004 – 8 Flora – Model 1

26. 29 October 2004 – 8 Flora – Model 2

27. 12 June 2006 – 2 Pallas – Model 1

28. 12 June 2006 – 2 Pallas – Model 2

29. 22 January 2008 – 13 Egeria – Model 1

30. 22 January 2008 – 13 Egeria – Model 2

31. Multi-Year Model Fits How do models fit the same asteroid over time?

32. 13 April 2007 – 19 Fortuna

33. 18 June 2008 – 19 Fortuna – 1 year later

34. 3 October 2006 – 25 Phocaea

35. 16 April 2012 – 25 Phocaea – 5+ years later

36. 9 March 2008 – 45 Eugenia

37. 13 June 2014 – 45 Eugenia – 6+ years later

38. 7 September 2001 – 9 Metis (5 events)

39. 12 September 2008 – 9 Metis – 7 years later – Model 1

40. 12 September 2008 – 9 Metis – 7 years later – Model 2

41. 29 December 2008 – 9 Metis – 7 years later

42. 7 March 2014 – 9 Metis – 12.5 years later

43. 7 October 1981 – 88 Thisbe (2 events)

44. 21 February 2007 – 88 Thisbe – 25+ years later

45. 22 November 1982 – 93 Minerva (3 events)

46. 24 December 2010 – 93 Minerva – 28 years later

47. 6 September 2014 – 93 Minerva – 32 years later

48. References “DAMIT: a database of asteroid models” J. Durech , V. Sidorin, and M. Kaasalainen, 2010 http://astro.troja.mff.cuni.cz/projects/asteroids3D/download/durech_et_at_damit_preprint.pdf Webpage http://astro.troja.mff.cuni.cz/projects/asteroids3D/web.php

49. Comments? Questions?