large scale triangulation: from struve to refsdal
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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
Professor with students
First Republic
Uniküla-Rannaküla
baseline
Wilhelm Struve1816-1819Triangulation of Livonia
Simuna-Võivere baselineNorthern part of Struve’s Arc
Sharpest angles
Size/Baseline
112 10
tan( )S
x
Large scale triangulation
Parallax measurements
Wilhelm Struve1835-1836
611.65 10
tan( )S
x
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
Astrometric tradition lives on
Valeri MalyutoHIPPARCOS,GAIA
Indrek KolkaGAIA
S Andromedae (1885)
Karl Ernst Albrecht Hartwig (1851 — 1923)
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
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
Refsdal’s method
6'' 1314.95 10
tan( )S
x
Sjur Refsdal December 30, 1935 – January 29, 2009
Quasars!
Sleeping beauty (said Virginia Trimble)
First gravitational lens system QSO 0957+561
1979Dennis Walsh, Bob Carswell, and Ray Weymann using the Kitt Peak National Observatory 2.1 meter telescope.
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
Sjur Refsdal and Rudy Schild
2002, Soomaa, Estonia
Oslo, 1997-1998 Centre of Advanced Studies
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
Prediction
Full observable universe will be covered at log(S)=15.46 or in 2036
Weak and strong lensing
Mapping of near by dark matter haloes
Second stage
Dark matter mapping methods
• Millisecond pulsar timing, Shapiro delays (Siegel et al).
• Microlensing (magnification events)
• Large scale weak lensing studies
• Strong lensing, precise modeling
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)
Final stage uses already compiled maps
Collectingtime delays forfast and faraway events
Galaxy microlensing taken into account
Paths through the real space
Can be done for:
• Gravitational waves (LISA)
• Gamma ray burst
• Far away quasars
• Yet unknown violent fast, bright, violent events
Conclusions
• Hamburg-Estonia connections (not taking into account Bernhard Schmidt – who worked 1927-1935 in Hamburg Observatory).
• Keep the first result!
• 2036 – Mission completed!
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