Erik HErik Høøg g -- 20122012

Niels Bohr Institute Niels Bohr Institute -- CopenhagenCopenhagen

Content:• Photoelectric effect: Hipparcos• CCD astrometry with Roemer• From Roemer to GAIA and Gaia• Astrometry in 2040 AD ???

Hipparcos successors in the 1990sHipparcos successors in the 1990sThe development towards CCD astrometry with GaiaThe development towards CCD astrometry with Gaia

IAU GA in Beijing

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•• August 1989: Hipparcos launchedAugust 1989: Hipparcos launched•• Data reduction occupied us all, also me, Data reduction occupied us all, also me,

but a visit to USSR in 1990 gave me impuls:but a visit to USSR in 1990 gave me impuls:•• 19901990--91 dialogue with Russian colleagues91 dialogue with Russian colleagues•• Proposal HProposal Høøg 1992: g 1992:

Scanning mission with Scanning mission with CCDs : RoemerCCDs : Roemer

How Gaia beganHow Gaia began

In the USA 1989 POINTS and CCDs in TDI mode

POINTS / SIM :POINTS / SIM :2 pairs of pointed telescopes2 pairs of pointed telescopes2 m separation, 0.25 2 m separation, 0.25 ØØinterferometry interferometry 0.005 mas0.005 mas

”” POINTS is the naturalPOINTS is the naturalinterferometric descendantinterferometric descendantof HIPPARCOSof HIPPARCOS ”” (Chandler(Chandler& Reasenberg in1989)& Reasenberg in1989)

CCDs in TDI mode CCDs in TDI mode on a meridianon a meridiancircle planned by Stone & Monetcircle planned by Stone & Monetin 1989in 1989

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In the USA up to 1994 three space astrometry projects

POINTS / SIM : 1989, interferometer 0.005 masPOINTS / SIM : 1989, interferometer 0.005 mas

Hubble Space Telescope : Launched 1990Hubble Space Telescope : Launched 1990FGS and Wide Field/Planetary Camera 2 masFGS and Wide Field/Planetary Camera 2 mas

Newcomb : 1994, design concept, Newcomb : 1994, design concept, 3 or 4 stacked Michelson interferometers,3 or 4 stacked Michelson interferometers,0.1 mas for 1000 stars, Johnston et al. 19950.1 mas for 1000 stars, Johnston et al. 1995

All three aimed for All three aimed for very high accuracyvery high accuracyAll three with All three with pointed telescopespointed telescopes

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In the USSR by 1989 three successors to Hipparcos proposed

Lomonossov : 1 m Lomonossov : 1 m ØØ, F=50 m pointing telescope 1 mas, F=50 m pointing telescope 1 mas

REGATTAREGATTA --ASTRO : scanning, 10 mas accuracyASTRO : scanning, 10 mas accuracy

AIST : 2 telescopes, 0.25 m AIST : 2 telescopes, 0.25 m ØØ, scanning, 1 mas, scanning, 1 mas

All three aimed for launch before 1997All three aimed for launch before 1997and >1 mas accuracy and >1 mas accuracy –– similar to Hipparcossimilar to Hipparcos

Aim: Get very accurate proper motionsAim: Get very accurate proper motionsfor the 100 000 Hipparcos starsfor the 100 000 Hipparcos stars

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In the USSR by 1989 AIST

AIST : AIST : 2 telescopes, 2 telescopes, 0.25 m 0.25 m ØØ, F=3 m, F=3 m

Scanning mode, but Scanning mode, but different fromdifferent fromHipparcos scannningHipparcos scannning

CCD detectors, but how?CCD detectors, but how?

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Dialogue with Russians 1990-91 Here on a visit to Copenhagen in 1991

Valeri Makarov Valeri Makarov : 7 years Tycho/Tycho: 7 years Tycho/Tycho --2 in 2 in Copenhagen then USACopenhagen then USA

Mark ChubeyMark ChubeyAIST leaderAIST leader

V. YershovV. Yershov

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Hipparcos-2presented in Moscow in June 1991

Several improvements, but still photoelectric Several improvements, but still photoelectric Hipparcos system Hipparcos system with IDT and photomultiplierswith IDT and photomultipliers ::

1 mas for 400 000 stars1 mas for 400 000 stars0.2 mas/year proper motions for 120 000 Hipparcos s tars0.2 mas/year proper motions for 120 000 Hipparcos s tars

Proposed by HProposed by H øøg & Chubey in Moscow in June 1991g & Chubey in Moscow in June 1991and as poster in Buenos Aires later in 1991and as poster in Buenos Aires later in 1991

Then began my Then began my study of CCDs study of CCDs ……

Always reporting in the Hipparcos Science Team Always reporting in the Hipparcos Science Team ……

. .

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CCDs with modulationwith modulation for Hipparcos-2in report Jan.1992

Presented by HPresented by H øøg & Lindegren in Shanghai in Sept. 1992g & Lindegren in Shanghai in Sept. 19920.5 mas at 10th mag from 2.5 years mission0.5 mas at 10th mag from 2.5 years mission

In May 1992 began my study of In May 1992 began my study of direct imaging on CCDs :direct imaging on CCDs :Roemer Roemer ………… GaiaGaia 9

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Focal plane of Roemer - Høg Sept. 1992

Sampling and CCDs

Always reporting in the Hipparcos Always reporting in the Hipparcos Science Team Science Team ……

2 telescopes 26 cm 2 telescopes 26 cm ØØ5 years mission5 years missionAstrometry Astrometry ++--0.1 mas 0.1 mas at 14 mag at 14 mag Photometry Photometry ++--0.006 mag 0.006 mag in V in V ……

CCDs, direct imaging, elongated pixels, TDI, CCDs, direct imaging, elongated pixels, TDI, short CCDs for bright stars, sampling windowsshort CCDs for bright stars, sampling windows

Roemer was presented in Shanghai in September 1992 – IAU Symp. 156

In China you are askedIn China you are askedto sing or tell a storyto sing or tell a story

at the at the conference dinnerconference dinner

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Innovations in Roemer 1992 comp. with Hipparcos and retained in Gaia

1. CCDs = high QE1. CCDs = high QE2. Direct imaging, no modulation2. Direct imaging, no modulation3. Rectangular pixels corresponding to optical reso lution3. Rectangular pixels corresponding to optical reso lution4. TDI mode4. TDI mode

5. Short CCDs for bright stars5. Short CCDs for bright stars6. Sampling: Windows for reading CCDs and transmiss ion6. Sampling: Windows for reading CCDs and transmiss ion7. Astrometry + multicolour photometry7. Astrometry + multicolour photometry8. Much higher accuracy ~ 10x 8. Much higher accuracy ~ 10x ~ 100 muas~ 100 muas

These 8 innovations are retained in GaiaThese 8 innovations are retained in Gaia12February 2011 Erik Høg

Roemer proposed as M3 mission in 1993

Roemer meeting March 1993 in Copenhagen : Roemer meeting March 1993 in Copenhagen : Kovalevsky, Kovalevsky, Lindegren, Lindegren, Halbwachs, Makarov, Halbwachs, Makarov, HHøøg, g, van Leeuwen, van Leeuwen, Knude Knude –– missing here: missing here: Bastian,Bastian, Gilmore, Gilmore, Labeyrie, Pel, Schrijver, Stabell, ThejllLabeyrie, Pel, Schrijver, Stabell, Thejll

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Roemer proposed as M3 mission in 1993M3 = Third Medium Size ESA Mission

Roemer proposed for M3 by Roemer proposed for M3 by Lindegren et al. in May 1993Lindegren et al. in May 1993

Proposal rated highly by the ESA Proposal rated highly by the ESA advisory committees advisory committees –– scientificallyscientificallythe highest rank of all mediumthe highest rank of all medium --sized missions sized missions by the Astronomy Working Group by the Astronomy Working Group

But then referred to a But then referred to a Cornerstone MissionCornerstone Missionif 10if 10 --20 muas could be demonstrated20 muas could be demonstrated

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Proposal for an ESA Cornerstone Missionwith study of a large Roemer and GAIA

Cover letter by Lindegren of 12 Oct. 1993Cover letter by Lindegren of 12 Oct. 1993proposes initially to study together a proposes initially to study together a ”” large Roemerlarge Roemer ”” and and GAIAGAIA as two optionsas two options ……”” without a priori excluding eitherwithout a priori excluding either ..””www.astro.ku.dk/~erik/gaia_proposal_1993.pdfcontains 6 pages= letter + proposalcontains 6 pages= letter + proposalConfirmation in April 1994: Confirmation in April 1994: www.astro.ku.dk/~erik/beckwith_lindegren.pdfwww.astro.ku.dk/~erik/beckwith_lindegren.pdf

Lindegren in mail to HLindegren in mail to H øøg of 3 Sep. 2010:g of 3 Sep. 2010:“…The GAIA proposal of course does not mention the "large Roemer“… I never received any response (as far as I can remember) concerning the "large Roemer", and when the study was initiated that option had apparently been forgotten and the name GAIA (or Gaia) had stuck.”

Lennart Lindegren (2003)Lennart Lindegren (2003)

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Two innovations in GAIA 1993 compared with Roemer

GAIA proposed by Lindegren, Perryman et al.GAIA proposed by Lindegren, Perryman et al.GAIA=Global Astrometric GAIA=Global Astrometric InterferometerInterferometer for Astrophysicsfor Astrophysics

1. Fizeau interferometers1. Fizeau interferometers2. Much higher accuracy :2. Much higher accuracy :

1010--20 muas at V=1520 muas at V=15

The interferometry fascinated us in 1993The interferometry fascinated us in 1993ButBut only the innovation about higheronly the innovation about higher

accuracy has been retained in Gaiaaccuracy has been retained in Gaia

Lennart Lindegren (2003)Lennart Lindegren (2003) Michael Perryman (2009)Michael Perryman (2009)

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GAIA Oct.1993 / Sept.1994 by Lindegren, Perryman et al.

3 stacked Fizeau interferometers3 stacked Fizeau interferometersModulation by gridModulation by grid

Detection by CCDs in August 1994: Detection by CCDs in August 1994: Most of the field detects modulation,Most of the field detects modulation,the corners apply direct imaging, i.e. TDIthe corners apply direct imaging, i.e. TDI

One of the interferometers One of the interferometers Diffraction Diffraction imageimage

3 m

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Innovation in Roemer+ Aug. 1994 by Høgcomp. with GAIA and retained in Gaia

Accuracy 20 muas Accuracy 20 muas at 13 mag with at 13 mag with direct imaging direct imaging / 2.5 yr/ 2.5 yr

This innovation This innovation retained in Gaiaretained in Gaia

70 cm 70 cm ØØ

= The 1st large Roemer= The 1st large Roemer

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In the USA in Dec.1995 space astrometry project: FAME

FAME FAME proposed by Johnston, Seidelmann et al.proposed by Johnston, Seidelmann et al.

Fizeau interferometerFizeau interferometeron scanning satelliteon scanning satelliteNo photometry now !No photometry now !

a version in June had spectra !a version in June had spectra !

I was for a time a member of I was for a time a member of the FAME team andthe FAME team andreceived this optical system received this optical system of FAME in Septemberof FAME in September

I then designed a new system I then designed a new system for GAIA in October 1995 for GAIA in October 1995 ……

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New optical system for GAIA in 1995 Gregorian system – dispersed fringes

GAIA95 proposed by HGAIA95 proposed by H øøg, Fabricius & Makarovg, Fabricius & Makarov

Fizeau interferometerD=1.5 m

Prism

Dispersed fringes perpendicular to scan

Diffraction image

Scan

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GAIA95 was starting point for DIVA in 1996

DIVADIVA proposed by Rproposed by R ööser, Bastian, de Boer, Hser, Bastian, de Boer, H øøg et al. g et al. in August 1996 for a Phase A study in August 1996 for a Phase A study in Germanyin Germany

D=15 cmD=15 cm , 1.3 year, 0.8 mas, at 10.5 mag, >1 million stars, 1.3 year, 0.8 mas, at 10.5 mag, >1 million starsMultiMulti --colour photometry by dispersed fringescolour photometry by dispersed fringes

GAIA95 was considered for GAIA in 1997GAIA95 was considered for GAIA in 1997

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Cornerstone study selected in 1997

Interferometry fascinated everybodyInterferometry fascinated everybodyIt led us to propose GAIA in 1993It led us to propose GAIA in 1993

and to elaborate such ideasand to elaborate such ideas

In 1997 the ESA Committees selectedIn 1997 the ESA Committees selectedspace space interferometryinterferometry for Cornerstone studyfor Cornerstone study

Invitation 11 March 1997: Invitation 11 March 1997: www.astro.ku.dk/~erik/esa_sag_invitation_970311.pdfwww.astro.ku.dk/~erik/esa_sag_invitation_970311.pdf

Without GAIA no astrometry Cornerstone!Without GAIA no astrometry Cornerstone!

22ESTEC

Telescopes and payload of GAIA 1993 - 1997

3 stacked Fizeau interferometers + telescope for rad ial velociti3 stacked Fizeau interferometers + telescope for rad ial velociti esesThe18 mirrors and 3 focal planes of the interferometers requirThe18 mirrors and 3 focal planes of the interferometers require e

high stability of order nanometers and microarcsecondshigh stability of order nanometers and microarcseconds

3 m

1

2

3

MMS design of June 1997

3

2

1

ARVI - radial velocities proposed 1995

~ GAIA 1993

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Some steps during development of Gaia

Radial velocities proposed in 1995 by Favata & Perr yman

GAIA Science Advisory Group first meeting March 1997Radial velocities with separate telescope in June 1 997Input catalogue dropped in July 1997Sampling schemes 1997-2007

Interferometry dropped on January 15, 1998 – again direct imaging = ”large Roemer”

The name GAIA changed to Gaia in 2003-05

Prism photometry instead of filters in 2005Radial velocities in same telescope in 2005 24

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Telescopes and payload of Telescopes and payload of GAIA = 2GAIA = 2ndnd large Roemerlarge RoemerMMS design of mid MMS design of mid 1998: 4 focal planes, 3 telescopes1998: 4 focal planes, 3 telescopes

Silicon Carbid mirrorsSilicon Carbid mirrorsRotation axis (6 h)Rotation axis (6 h)

Anastigmatic offAnastigmatic off--axis telescopesaxis telescopes

SiC toroidalSiC toroidalstructurestructure

(optical bench)(optical bench)

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Telescopes and payload of Telescopes and payload of Gaia = 3Gaia = 3rdrd large Roemerlarge Roemer

2005 2005 –– One focal plane One focal plane -- Launch 2013 asLaunch 2013 as RRGaia Gaia (~(~WWMAP)MAP)Two SiC primary mirrorsTwo SiC primary mirrors

1.45 1.45 ×× 0.50 m0.50 m22 at 106.5at 106.5°°

Basic angleBasic anglemonitoring systemmonitoring system

CombinedCombinedfocal planefocal plane

(CCDs)(CCDs)F = 35 mF = 35 m

Rotation axis (6 h)Rotation axis (6 h)

Figure courtesy EADSFigure courtesy EADS--AstriumAstrium

Superposition of Superposition of two Fields of View two Fields of View

SiC toroidalSiC toroidalstructurestructure

(optical bench)(optical bench)

Two anastigmatic offTwo anastigmatic off--axis telescopesaxis telescopes

Astrometric Accuracy versus Time

Hipparchus/Ptolemy - 1000 stars

1000

100

10

arcsec 1

0.1

0.01

0.001

0.0001

0.00001

Erik Høg1995/2009 150 BC … 1600 1800 2000 Year

The Landgrave of Hesse - 1000 stars

FK5 - 1500

Positions

Parallaxes =

Small angles

All parameters

Tycho-2- 2.5 million

Hipparcos - 120,000

Bessel - 1 star

Jenkins - 6000

Gaia 23 million(SIM - 10,000)

USNO - 360

ROEMER - 45 millionProposal 1992

Flamsteed - 3000

Tycho Brahe - 1000

Argelander - 34,000Bradley - aberration

PPM - 379,000

Gaia- 1200 million

Lalande - 50,000

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A lesson to learn:A lesson to learn:Think Think of 2040 of 2040 nownow

Astrometry???Astrometry???

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Encourage: Encourage: Education Education –– Creativity Creativity –– New projectsNew projects

High precision astrometry by : High precision astrometry by : Optical/NIR VLBI Pulsar timingOptical/NIR VLBI Pulsar timing