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Large scale triangulation: from Struve to Refsdal
Jaan Pelt
Tartu Observatory
Expanding the Universe,
Conference in Tartu 27-29 April 2011
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Professor with students
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First Republic
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Uniküla-Rannaküla
baseline
Wilhelm Struve1816-1819Triangulation of Livonia
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Simuna-Võivere baselineNorthern part of Struve’s Arc
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Sharpest angles
Size/Baseline
112 10
tan( )S
x
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Large scale triangulation
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Parallax measurements
Wilhelm Struve1835-1836
611.65 10
tan( )S
x
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α Aquilae (Tartu Pubs. III, 1822) 0".181 current 0".198
α Lyrae (1835-1836) 0".125±0.055 (1840 AN) 0".2613 ± 0".0254 current 0".123
Friedrich Georg Wilhelm Struve b. 1793 Altona, Hamburgd. 1864 St. Petersburg
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Astrometric tradition lives on
Valeri MalyutoHIPPARCOS,GAIA
Indrek KolkaGAIA
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S Andromedae (1885)
Karl Ernst Albrecht Hartwig (1851 — 1923)
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From orbital speeds to Eq.1
0
20
, 1, 1
( ) ( .1)
GMv
r
GMw M r
r
v MEq
w r
1922,ApJ 55,406
Among other: Rector of Baltic University (1946-1948) - Hamburg
Ernst Julius Öpik 22. oktoober 1893 – 10. september 1985
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And now to distance!20
20
2 220
20
( ) ,
( ) , triangle!!!sin( )
[ ]( ) , because ,
sin( ) 1
1sin( )( )
[ ]
ML
ML
v M
w rv M
w D
v D l L D
w D l
vD
l w
919.3 10
tan( )S
x
150''
Öpik 1921 785000 pcÖpik 1922 450000 pcHubble 1929 275000 pcCurrent 690000 pc
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Refsdal’s method
6'' 1314.95 10
tan( )S
x
Sjur Refsdal December 30, 1935 – January 29, 2009
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Quasars!
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Sleeping beauty (said Virginia Trimble)
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First gravitational lens system QSO 0957+561
1979Dennis Walsh, Bob Carswell, and Ray Weymann using the Kitt Peak National Observatory 2.1 meter telescope.
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Vanderriest et al. 1989 415 20 days
Controversy of baseline
measurement(time delay)
Press et al. 1992 536 5 days
Pelt et al. 1994 (Hamburg) 415 or 536 days
Pelt et al. 1996 (Hamburg) 423 6 daysKundić et al. 1997 417 3 daysPelt et al. 1998 (Oslo) 416.3 1.7 days
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Sjur Refsdal and Rudy Schild
2002, Soomaa, Estonia
Oslo, 1997-1998 Centre of Advanced Studies
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How it does?
Meta surveys
Best single lens( B1608+656, Suyu et al): 70.6 3.1First lens system (QSO 0957+561, Fadely et al):
6.78.579.3
Canonical (Freedman): 73 2 4
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Prediction
Full observable universe will be covered at log(S)=15.46 or in 2036
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Weak and strong lensing
Mapping of near by dark matter haloes
Second stage
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Dark matter mapping methods
• Millisecond pulsar timing, Shapiro delays (Siegel et al).
• Microlensing (magnification events)
• Large scale weak lensing studies
• Strong lensing, precise modeling
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How this will be done?
• 3000-4000 strong lens systems
• 300-400 lensed supernovae
• Abundant weak lensing data base
• Hundreds of thousands of microlensing events
Just one example – LSST(Large Synoptic Survey Telescope)
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Final stage uses already compiled maps
Collectingtime delays forfast and faraway events
Galaxy microlensing taken into account
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Paths through the real space
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Can be done for:
• Gravitational waves (LISA)
• Gamma ray burst
• Far away quasars
• Yet unknown violent fast, bright, violent events
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Conclusions
• Hamburg-Estonia connections (not taking into account Bernhard Schmidt – who worked 1927-1935 in Hamburg Observatory).
• Keep the first result!
• 2036 – Mission completed!