Asteroidal Occultations around the world

1. Asteroidal Occultations around the world Summary of the best events in last 2 years

2. The number of events continues to grow…

3. Number of successful events by region, and max # observers - 2010 • Australasia 50 (5 obs, 6 stns) • Europe 51 (231 obs) • Japan 25 (34 obs) • US 106 (14 obs, 18 stns) Japan has a much smaller land area than the other regions; Australasia has a much smaller population

4. Double stars discovered in asteroidal occultations • New double stars can be discovered in an asteroidal occultation • Separations are usually in the range 0.1” to 0.001” • If several observers, the uncertainty in separation can be less than 1 milli-arcsecond

5. 9 double stars discovered in last 24 months Star number Sep ( ” ) P.A. Date Asteroid 0819-00852-1 .0075 ± 0.0007 124.9 ± 5.2 2009 Apr 16 336 Lacadiera 2255-01354-1 .1448 ± 0.0004 192.4 ± 0.2 2009 Jul 19 790 Pretoria 5186-00724-1 .0017 ± 0.0001 -87.0 ± 3.2 2009 Jul 28 732 Tjilaki HIP 116660 .0178 19.0 2009 Sep 9 1157 Arabia 0250-00557-1 .0024 128.1 ± 0.4 2009 Nov 9 79 Eurynome 6324-01847-1 .0165 ± 0.0001 180.3 ± 0.5 2010 Jun 8 371 Bohemia 2332-01054-1 .0012 188.7 2010 Aug 31 695 Bella 2U 41168613 .0283 ± 0.0002 205.1 ± 0.8 2010 Oct 20 675 Ludmilla HIP 46249 .0065 ± 0.0011 50.2 ±12.2 2011 Jan 24 160 Una

6. An odd-shaped asteroid- or –(234) Barbara has a heart • 2009 Nov 21, Florida + Germany • 28 stations – but only 13 observers • Degenhardt – 7 stations • Dunham – 4 stations • Maley – 5 stations • Venable – 3 stations

8. Issues with Barbara • Asteroid may be a contact binary asteroid • There were ‘timing issues’ with a couple of critical observations – which were resolved.

9. Roma occults δ Oph2010 Jul 08 • Path crossed Europe • Star mag 2.9 => naked eye event • Star has a significant diameter • Over 230 separate observations - most ever.

10. Star had a large diameter… Asteroid dia : 0.036” Star dia : 0.012” All events were gradual

11. Roma – sample light curve

12. Roma – fit is poor because of inconsistent light levels used for event times

13. Roma profile using good observations

14. Other well-observed events • A selection of the best observed events that show the profile of the asteroid.

15. 709 Pretoria

16. (449) Hamburga

17. (216) Kleopatra(the dog-bone asteroid)

18. (81) Terpsichore

19. (80) Sappho

20. (16) Psyche (timing issue with one chord)

21. (695) Bella

22. (96) Aegle

23. (93) Minerva

24. (212) Medea

25. (160) Una

26. (11) Parthenope (timing issues)