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