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2012 Astronomical Telescope + Instrumentation in Amsterdam, 3 July 2012

Developments of the wideband spectropolarimeter of the Domeless Solar Telescope at Hida Observatory. 2012 Astronomical Telescope + Instrumentation in Amsterdam, 3 July 2012 Tetsu Anan, Kiyoshi Ichimoto, Akihito Oi, Goichi Kimura, Yoshikazu Nakatani, Satoru Ueno (Kyoto University).

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2012 Astronomical Telescope + Instrumentation in Amsterdam, 3 July 2012

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  1. Developments of the wideband spectropolarimeter of the Domeless Solar Telescope at Hida Observatory 2012 Astronomical Telescope + Instrumentationin Amsterdam, 3 July 2012 Tetsu Anan, Kiyoshi Ichimoto, Akihito Oi, Goichi Kimura, Yoshikazu Nakatani, Satoru Ueno (Kyoto University)

  2. Solar polarimetric observation • Stokes vector • Zeeman effect => magnetic fields of photosphere U = 　− I = V map I map Q = 　− V = 　− PASJ intensity White：N Black：S view towards the sun Magnetic field of photosphere Photosphere HINODE/SOT

  3. Development goalSpectro-Polarimetric observation system • Science • Open a new window of plasma diagnostics • Zeeman and Hanle effect => magnetic fields of chromosphere • Consideration for science and instrument of Solar-C • Stark effect => electric fields • impact polarization => non-thermal particles • Scattering polarization => radiation fields • Instrument • precise spectropolarimetric observations(〜10-4) • wide range of wavelength in visible and near infrared (400〜1100 nm) 3/27

  4. Hida Observatory 4/27

  5. Hida Observatory 5/27

  6. Domeless Solar Telescope (DST) at Hida Observatory DST 24m above ground Vacuum Tube Horizontal Spectrograph Focal plane ground Modulator / Analyzer Vertical Spectrograph 14m under ground 6/27

  7. Modulator / Analyzer Iobs+ (θ、δ) Iobs− (θ、δ) Iin=Qin Iin=Vin Iobs+ Iin=Uin 360 270 0 180 90 7/27 θ [deg] Rotation angle θ Waveplate retardation δ Polarizer (Beam splitter)3 Wollaston prisms

  8. Retardation of Waveplate V Quartz Q,U APSAW http://astropribor.com/content/view/25/33/ 9/27

  9. DetectorGE1650 & XEVA640 Quantum efficieency Non-linearity of XEVA640 GE1650 ・ Measured value ー Function for calibration XEVA640 Maximum frame rate : 30Hz To achieve photon noise〜10−3 　30 sec (visible), 60 sec (near infrared) Sampling : 0.4arcsec, 4pm 10/27

  10. Rotation angle Rotating waveplate Detector CCD Camera：GE1650 IR Camera：XEVA640 Origin sensor accuracy of θ 〜 0.07°  Error of QUV/I〜10−4 Origin sensor produces a trigger for the camera to start a sequence of exposures 8/27

  11. Instrumental polarization of DST Entrance window • System • DST has 2 oblique mirrors (Newton & Coude) => Necessity to calibrate instrumental polarization of DST • DST polarization model • Parameters • Solar position (Hour Angle & Zenith distance) • Each optics • Stray light Newton mirror Coude mirror Secondary mirror Exit window Primary mirror Slit Modulator / Analyzer 11/27 Vertical Spectrograph

  12. DST polarization model • Mueller matrix MDST : 4×4 matrix Den MN MDST = R(φV)MscatDexMCMGR(φC)MNMPDenR(φN) MG MC MP, MN, MG, MC Dex MP Slit Modulator / Analyzer 12/27

  13. Idealized DST polarization model • Idealization Dex = Dex = identity matrix, Den M’DST = R(φV)MscatMCMGR(φC)MNMPR(φN) MN MG MC Unknown parameters : pN, pC, τN, τC, s MN, MC Dex MP Slit Modulator / Analyzer 13/27

  14. How to develop DST polarization model • Induce a well known polarization into DST • Observe IQUV of the polarization on the slit Unknown parameters of idealized MDST Remotely controllable turret Battery & Wireless set Linear polarizer peeped through 8 holes Solar panel 14/27

  15. Entrance window 15/27

  16. Remotely controllable turret mask Nakatani, Kimura, Anan, Ichimoto 16/27

  17. Remotely controllable turret under the mask Hole of mask Hole of panel Linear polarizer Under the mask, there is a remotely controllable turret accommodating 8 linear polarizers & 8 holes Nakatani, Kimura, Anan, Ichimoto 17/27

  18. Remotely controllable turret under the mask Hole of mask Hole of panel Linear polarizer Nakatani, Kimura, Anan, Ichimoto 18/27

  19. Remotely controllable turret under the mask Hole of mask Hole of panel Linear polarizer Machine produce polarizations (I,Q,U,V) = (1,0,0,0), (1,±1,0,0), (1,0,±1,0) Nakatani, Kimura, Anan, Ichimoto 19/27

  20. Remotely controllable turret Circuit Turret Control circuit Backflow preventer Battery Solar cell on the entrance window of DST Control circuit PC Wireless in observation room Wireless 20/27

  21. Observation 21/27

  22. DST instrumental polarizationCaⅡ854.2 nm Red : observation Black : DST model Q=U=V=0 I = +Q I = −Q I = +U I = −U 1 0.04 0.00 0 Q/ I −0.04 −1 1 0.04 0 0.00 U/ I −0.04 −1 1 0.024 0 V/ I 0.020 −1 0.016 20 0 60 40 20 0 −20 60 40 −20 20 20 0 20 0 60 0 60 40 60 40 40 −20 −20 −20 HA [deg] HA [deg] HA [deg] HA [deg] HA [deg] Disk center, Quiet region, continuum • pN=−0.050、τN=346°.0、pC=0.003、τC=27°.5 + stray 3% • Fitting residual 〜 0.001 at I2>>Q2+U2+V2 22/27

  23. DST instrumental polarization5 parameters −0.01 −0.02 pN −0.04 −0.05 0 −10 τN[deg] −20 −30 0.02 0.00 pC −0.02 −0.04 40 τC[deg] 20 0 0.08 0.04 s 0.00 600 400 800 1000 1200 Telescope position Red : west Blue: east Wavelength [nm] 23/27

  24. Flare Kernel Ca II (854 nm) Hα image 1.0 I 0.6 0.04 0.00 Q/ I −0.04 0.04 U/ I 0.00 −0.04 Slit 0.02 V/ I 0.00 −0.02 854.0 855.0 854.5 Wavelength [nm] Polarization sensitivity (V/I)：〜10−3 [[Resolution]] λ ：0.07 Å/pix Slit ：0.8 arcsec/pix T ：〜19 sec Solid line : after calibration Dotted line : before calibration 24/27

  25. Polarization sensitivity (V/I)：〜10−3 [[Resolution]] λ ：0.03 Å/pix Slit ：0.6 arcsec/pix T ：〜28 sec Umbral oscillation 1083 nm DST Hα Slit position I Q/ I Si Si Wavelength [pix] Wavelength [pix] He He H2O H2O Slit Slit U/ I V/ I Si Si Wavelength [pix] Wavelength [pix] He He H2O H2O Slit [pix] Slit [pix] 25/27

  26. Umbral oscillation I V/ I 8000 8000 6000 6000 Time [sec] Time [sec] 4000 4000 2000 2000 0 0 10834 10830 10832 10828 10834 10826 10830 10826 10828 10832 Wavelength [Å] Wavelength [Å] 26/27

  27. Summary • Modulator, Analyzer, and detector • A rotating achromatic waveplate & Wollaston prisms • Wide wavelength range (400 〜 1100 nm) • Systematic error of QUV/I 〜10−4 • To achieve photon noise 〜10−3〜30 sec (visible), 〜60 sec (near infrared) • DST instrumental polarization • We developed DST polarization model for wide wavelength range • Accuracy (cross-talk) 〜10−3at I2 >> Q2+U2+V2 Slit Modulator / Analyzer 27/27 Vertical Spectrograph

  28. Thank you for listening

  29. Summary • Modulator/Analyzer • a rotating achromatic waveplate & Wollaston prisms • Systematic error of QUV/I 〜10−4 • DST instrumental polarization • We developed DST polarization model • Accuracy (cross-talk) 〜10−3 at I2 >> Q2+U2+V2 • But we need re-calibration by using observed profiles

  30. 超広帯域波長板 Astropribor Achromatic True Zero-Order Waveplates (APAW)Astropribor Super-Achromatic True Zero-Order Waveplates (APSAW) Quartz zero-order 420 700 560 1120nm 840 980 http://astropribor.com/content/view/25/33/ APSAW f25mm ～ 3000ユーロ 5 birefringent polymers

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