Lunar
Occultations
of Close
Double Stars
Occultation of R946,
2011 November 14
The why and wherefore of
observing these events
NACAA 2014 April 20
Occultations Session
Brian Loader RASNZ Occultation Section
SAO 160149
2013 September 12
1
SAO 160149 Occultation Video Frame
2
Occultation Light Curve, Single Star
3
Occultation Light Curve for SAO 160149
4
Double Star Occultation, Light Curve
Secondary Intensity
Step Length
(seconds)
Primary Intensity
5
Double Star Occultation, Light Curve
176 ± 78
Step Length
(seconds)
1.16 s
367 ± 42
6
Double – Fainter Star second
7
Double Reappearance
8
Double Star Programme Aims
Accurate times of both events
Position Angle and Separation
and Magnitudes
md
Discovery of new doubles
Confirmation / Rejection
Publication of results
9
Solution for R68 using OCCULT
N
EE
Prediction: 0.092” 258.37°
10
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.
11
Total Number of Observations
Archived as at 2014 April 6
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
12
Numbers of Observations Received
as at 2014 April 6
WDS ‘double’
WDS ‘single’
No. of
Obsn.
393
148
OCc ‘double’
OCc ‘single’
Discoveries
Doubtful Dbl
35
498
109
98
19
310
82
75
8
125
14
15
Wide Dbl >3”
80
64
11
1331
855
294
Group
TOTALS
No. of
stars
209
96
No. > 1
Obsn.
87
34
Max obsns.
per star
7(+2 nil)
4
3
6
6(+2 nil)
4
5
13
Numbers of Observers by Country
Australia
New Zealand
11
4
Japan
17
USA
9
Europe
7
14
Publication
Suitable observations are published in the on-line
Journal of Double Stars Observations.
http://www.jdso.org
15
Discovery Papers
16
JDSO July 2010
17
JDSO July 2011
18
JDSO October 2012
19
JDSO April 2014
20
Known doubles, PA and
Separation Measured
21
Occultation Discoveries
22
Possible Double Stars shown
to be single
23
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
24
25