Lunar Occultations of Close Double Stars Occultation of R946, 2011 November 14 Lunar Occultations of Close Double Stars The why and wherefore of observing these events NACAA 2014 April 20 Occultations Session Brian Loader RASNZ Occultation Section SAO 160149 2013 September 12

SAO 160149 Occultation Video Frame

Occultation Light Curve, Single Star

Occultation Light Curve for SAO 160149

Double Star Occultation, Light Curve Secondary Intensity Step Length (seconds) Primary Intensity

Double Star Occultation, Light Curve 176 ± 78 Step Length (seconds) 1.16 s 367 ± 42

Double – Fainter Star second

Double Reappearance

Double Star Programme Aims md Accurate times of both events Position Angle and Separation and Magnitudes Discovery of new doubles Confirmation / Rejection Publication of results

Solution for R68 using OCCULT E E Prediction: 0.092” 258.37°

2 or 3 video frames, ca 0.1 second … Possible Resolution 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 Year of Obsn. No of Obsn Cumulative up to end 2007 147 2008 75 222 2009 223 445 2010 249 694 2011 196 890 2012 1112 2013 184 1296 2014 65 1361

Numbers of Observations Received as at 2014 April 6 Group No. of Obsn. stars No. > 1 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 Wide Dbl >3” 80 64 11 5 TOTALS 1331 855 294

Numbers of Observers by Country Australia 11 New Zealand 4 Japan 17 USA 9 Europe 7

Publication Suitable observations are published in the on-line Journal of Double Stars Observations. http://www.jdso.org

Discovery Papers

JDSO July 2010

JDSO July 2011

JDSO October 2012

JDSO April 2014

Known doubles, PA and Separation Measured

Occultation Discoveries

Possible Double Stars shown to be single

Observer Separation 10° round the Moon’s limb projected on the Earth’s surface is ca 3° latitude Hobart – Melbourne ca 5° Melbourne – Sydney ca 4.5° Sydney – Brisbane ca 6° Brisbane – Rockhampton ca 4.2° Perth Adelaide Murrumbateman