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

Asteroidal Occultations around the world

Summary of the best events in last 2 years

The number of events continues to grow…

Number of successful events by region, and max # observers - 2010• Australasia50 (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

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

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

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

Issues with Barbara• Asteroid may be a contact binary

asteroid• There were ‘timing issues’ with a

couple of critical observations – which were resolved.

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.

Star had a large diameter…

Star dia : 0.012”

Asteroid dia : 0.036”

All events were gradual

Roma – sample light curve

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

Roma profile using good observations

Other well-observed events

• A selection of the best observed events that show the profile of the asteroid.

709 Pretoria

(449) Hamburga

(216) Kleopatra (the dog-bone asteroid)

(81) Terpsichore

(80) Sappho

(16) Psyche (timing issue with one chord)

(695) Bella

(96) Aegle

(93) Minerva

(212) Medea

(160) Una

(11) Parthenope (timing issues)