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LunarOccultations

of Close Double Stars

The why and wherefore of

observing these events

NACAA 2014 April 20

Occultations Session

Brian Loader RASNZ Occultation Section

Occultation of R946,

2011 November 14

SAO 1601492013 September 12

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SAO 160149 Occultation Video Frame

Occultation Light Curve, Single Star

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Occultation Light Curve for SAO 160149

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Double Star Occultation, Light Curve

Step Length (seconds)

Secondary Intensity

Primary Intensity

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Double Star Occultation, Light Curve

Step Length (seconds)

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176 ± 78

367 ± 421.16 s

Double – Fainter Star second

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Double Reappearance

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md

Double Star Programme Aims

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Position Angle and Separation

and Magnitudes

Discovery of new doubles

Confirmation / Rejection

Publication of results

Accurate times of both events

Solution for R68 using OCCULT

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Prediction: 0.092” 258.37°

N

EE

Possible Resolution

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2 or 3 video frames, ca 0.1 second …

… ca 30 to 35 milli arc-second...

60 m on the moon,

1AU at 100 light years.

Total Number of Observations Archived as at 2014 April 6

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Year of Obsn. No of Obsn Cumulative

up to end 2007 147 147

2008 75 222

2009 223 445

2010 249 694

2011 196 890

2012 222 1112

2013 184 1296

2014 65 1361

Numbers of Observations Receivedas at 2014 April 6

Group No. of Obsn.

No. of stars

No. > 1Obsn.

Max obsns.per star

WDS ‘double’ 393 209 87 7(+2 nil)

WDS ‘single’ 148 96 34 4

OCc ‘double’ 35 19 8 3

OCc ‘single’ 498 310 125 6

Discoveries 109 82 14 6(+2 nil)

Doubtful Dbl 98 75 15 4

Wide Dbl >3” 80 64 11 5

TOTALS 1331 855 294

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Numbers of Observers by Country

Australia 11New Zealand 4

Japan 17

USA 9

Europe 7

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Publication

Suitable observations are published in the on-line

Journal of Double Stars Observations.

http://www.jdso.org

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Discovery Papers

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JDSO July 2010

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JDSO July 2011

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JDSO October 2012

JDSO April 2014

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Known doubles, PA and Separation Measured

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Occultation Discoveries

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Possible Double Stars shown to be single

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Observer Separation

10° round the Moon’s limb projectedon the Earth’s surface is ca 3° latitude

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Hobart – Melbourne ca 5°

Sydney – Brisbane ca 6°

Melbourne – Sydney ca 4.5°

Brisbane – Rockhampton ca 4.2°

Perth Adelaide Murrumbateman

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