Occultation observations from around the world

Jan 2011 to Jun 2012

Dave Herald

Part 1

Lunar OccultationsSummary of observations

Jan. 2011 – Jun. 2012

# Observations by region

• Nth America 357• Australasia 1201• Japan 928• Europe 2082• MiddleEast 88

# Reported Grazes by region

• Nth America 2• Australasia 10• Japan 12• Europe 10• Middle East 2

• Total 36

Grazes with 5 or more observers2011 Apr 23 – Australia (5)

2011 Aug 24 – Europe (5)

2011 Sep 17 – Australia (6)

2012 Jan 29 – Japan (6)

Grazes by number of events (>10)• Date # events Region (# observers)• 2011 Sep 17 42 Australia (5)• 2011 Apr 8 36 Australia (3)• 2011 Nov 3 36 Japan (4)• 2011 Aug 22 34 USA (2)• 2011 Aug 24 31 Europe (5)• 2011 Oct 3 30 Japan (3)• 2012 Jan 29 28 Japan (6)• 2011 Mar 13 27 Japan (2)• 2011 Mar 11 20 Europe (2)• 2011 Dec 10 16 Japan (2)• 2012 Feb 4 14 Japan (1)• 2012 Apr 1 14 USA (1)• 2012 Apr 29 13 Europe (1)• 2011 May 7 12 Japan (1)• 2011 Jun 23 12 Australia (1)• 2012 Jan 29 12 Europe (1)

Double star observations

• # positive measures 94• # doubtful doubles 30• # definite ‘not double’ 58• # wide doubles 22

Reports collected and analysed by Brian Loader, New Zealand

Some double star solutionsR3287

S96610

S97067

S76152

Part 2

Asteroidal OccultationsSummary of the best events

Jan 2011 – June 2012

The number of events has flattened off…

Number of successful events by region, and max # sites: 2011/01 2012/06

• Australasia51 + 29 (7 sites)• Europe 51 + 31 (19 sites)• Japan 25 + 21 (25 sites)• US 76 + 27 (57 sites)

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

7 double stars discovered since Jan 2011

Star number Sep (mas) P.A. Date Asteroid

HIP46249 6.5 ± 1.1 50.2 ±12.2 2011 Jan 24 160 Una

1866-01091-1u 12.5 34.0 2011 Sep 13 177 Irma

2849-00430-1 0.6 68.4 ± 3.3 2012 Jan 13 759 Vinifera

HIP41337 93.0 93.0 2012 Jan 19 911 Agamemnon

1865-01119-1 23.0 99.0 2012 Feb 18 177 Irma

0126-00781-1 3.5 ± 1.0 38.3 ±14.6 2012 Mar 11 57 Mnemosyne

6273-01033-1 36.0 151.0 2012 Mar 20 44 Nysa

90 Antiope how good does it get!

Star diameter from 90 Antiope

• Dia from 61 light curves : 2.14 0.03 mas• For ‘complex’ occultations, correct

interpretation of a light curve may depend on results from adjacent chord => need to ensure data is available for re-analysis.

212 Medea 2011 Jan 8, Japan

144 Vibilia2011 Jan 25, Europe

(11) Parthenope2011 Jan 26, USA

(554) Perega2011 Mar 08, Europe

(360) Carlova2011 Aug 15, USA

(156) Xanthippe2011 Dec 26, ES + US

(329) Svea2011 Dec 28, Japan

(705) Erminia2012 Jan 2, Japan

(654) Zelinda2012 Jan 6, Japan

(266) Aline2012 Jan 17, Japan

(57) Mnemosyne2012 Mar 11, USA

(128) Nemesis2012 Mar 30, Australia

(1030) Vitja2012 Apr 28, CA + US

Any questions?