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On-orbit SOT performance

On-orbit SOT performance. Kiyoshi Ichimoto and SOT-team. Hinode workshop , 2007.12.8-10, Beijing. On-orbit performance of SOT reported in this presentation Image quality (BFI preliminary), Image stability, SP performance, Chromatic aberration, Focus stability, Throughput trend,

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On-orbit SOT performance

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  1. On-orbit SOT performance Kiyoshi Ichimoto and SOT-team Hinode workshop, 2007.12.8-10, Beijing

  2. On-orbit performance of SOT reported in this presentation • Image quality (BFI preliminary), • Image stability, • SP performance, • Chromatic aberration, • Focus stability, • Throughput trend, • Tunable filter status,

  3. Hinode SOT First Light image, 2006.10.25 Sun’s diameter ～1,400,000 km Above: The sun in white light (420 nm). Above-right and right:: From SOT showing in detail solar granulation (convection cells), and bright points between granules that are locations of concentrations of magnetic field. 10,000 km

  4. Close-up of granules in G-band (430nm) 4000km 16000km 0.2 arcsec Granules and bright points corresponding to tiny magnetic features are clearly seen in the movie. SOT achieves the diffraction limit resolution of 50cm-aperture telescope, 0.2 arcsec in the wavelength of 430 nm.

  5. 2006.10.31 CT servo-On, error signal/TM angle time profiles ~0.01arcsec rms Servo-off Image stability is perfect! 3 times better than the requirement.

  6. VLS-open VLS-close FW1 FW2 0.028”rms 0.031”rms 0.032”rms 0.036”rms 0.5s RSS=0.128”(3s) RSS=0.142”(3s) The XRT VLS produces a significant disturbance of SOT image, but, since the duration of its movement is very small fractions of time, there is no impact on SOT data.

  7. Spectropolarimeter performance SP takes excellent data!

  8. Two remarks on the SP feature Accuracy: DQUV/Ic ~ 10-3 (5s integ.) DI/Ic ~ 10-2 dominated by the compression noise Q=75 is a compromise.. No crosstalk. The best calibrated polarization instrument! Orbital drift of spectral image: Caused by deformation of FPP box. Minimized by careful heater setting, Corrected by sp_prep using slit pattern, no info. of absoluteline shift I-profile after flat correction Q=75

  9. Chromatic aberration Reimaging lens to FPP BFI has a chromatic aberration (caused by improper installation of a lens). Science impact is small but not zero. Reimaging lens 9step = 1.36mm 4step  WFE~21nm rms (< l/20 @430nm) No evidence of chromatic aberration in NFI

  10. G-band focus position history eclipse - Gradual drift of the focus is caused by shrinkage of the CFRP structure of OTA due to dehydration. --- expected behavior. -Focus offset between disk and limb pointing by ~5 steps. Cause is not well understood, but the response is fast enough to adjust the focus each time by OP.

  11. NGT NGT DAY+10min NGT-3min Focus drift in eclipse season The large focus drift is caused by excursion of the temperature of HDM in OTA in day/night cycle (expected). Eclipse season is certainly a ‘degraded performance period’ of SOT.

  12. BFI throughput history FG CCD baking The cause of the loss of throughput is not identified. No science impact at this point. eclipse

  13. NFI throughput history NFI 6302A lost ~ 60% of throughput due to a degradation of the blocking filter after a long exposure to the UV of sunlight. Since the blocking filter for 589nm (NaI D1) is durable against the UV, this filter is inserted in the beam always during the idle time of the NFI, thus the degradation of filters is suppressed in the current operation. There is no evidence of significant loss of throughput in other wavelengths of NFI and SP.

  14. Trend of the telescope temperature eclipse Telescope temperature is now stable. No evidence of significant progress of contamination in OTA.

  15. Tunable filter bubble Tunable elements which carries the bubbles are identified. TF6 big bubble TF5 ~1A TF Bubble in the FOV TF7 Small bubbles

  16. Appearance of tunable filter bubbles Current situation

  17. Tunable filter status; Images of the NFI contain blemishes which degrade or obscure the image over part of the field of view. The artifacts are caused by air bubbles in the index matching fluid inside the tunable filter. They distort and move when the filter is tuned. The locations of bubbles in the tunable filter were identified. To suppress the disturbance of bubbles, we are required to block 4 tuning elements out of 8.New software to enable such operation was successfully uploaded in Apr. 2007. This situation limits our capability of tuning the filter, but some useful schemes with a minimum usage of the 4 elements are still available and have been tested. NFI observing is usually done in one spectral line at one or a small number of wavelengths for extended periods of time. Rapid switching between lines is not allowed.

  18. The separation can not be free to prevent the motion of particular elements. Possible tuning w/o moving bubble elements

  19. Detection limit of NFI for weak magnetic fields Theoretical limit of NFI for detecting weak magnetic fields are evaluated using atlas solar spectrum. Symmetric wavelength observation in blue- and red-side of spectral lines with e=0.001 is considered. Zeeman sensitivities of the line, efficiency of the SOT’s polarization modulation, limitation of TF tuning step are taken into account, but no line shift. I’: line profiles convoluted by TF transmission curve 2nd moments of s and p-components 2007/11/22 K.I.

  20. +0.136A 0.04/1(km/s) Maybe better than intensity for seismology… Good for sunspot Dopplergram nfi_dopp_cal.pro

  21. FeI 5576 Dopplergram, 2007.07.14, 5576 + 0.136A

  22. NaI D1 Dopp./Mag. 2007.6.12, 5896 + 0.156A

  23. FeI 5250A IQUV 2007.6.21, -0.100/+0.136A

  24. Possible tuning w/o moving bubble elements This is possible; maybe useful for prominence /spicule Dopplergram. TF5,6 and 7 blocked

  25. Ha Doppler 2007.8.5, Ha+ 0.41A I Dopp.

  26. Original magnetogram is suffered from significant dI/dt noise (granule evolution) New scheme by T.Tarbell takes I+V in symmetric manner with time to reduce the dI/dt noise 6302 Test of New Shuttered IV Old OBS_ID 2: takes 3.9 sec V noise = 7.7 DN, S/N ~350 -20  +24 DN display New OBS_ID 61: takes 5.9 sec V noise = 6.5 DN, S/N > 400 -20  +24 DN display

  27. Seasonal variation of the orbital Doppler shift Good seasons for NFI

  28. Summary: • On-orbit SOT performance was reviewed. In general, SOT is excellent and sending outstanding data. • Some unexpected features exist; most of them are recovered by operation, i.e., frequent focus adjustment, frequent heater setting, corrections by calibration software… • The tunable filter contains air bubbles which degrade the NFI capability. • Schemes for tuning the filter without disturbing the bubbles have been developed and tested, and some useful procedures to obtain Dopplergram and magnetogram are now available. • October and March when the orbit of satellite becomes nearly perpendicular to the direction towards the sun provide a favorable condition for continuous runs of the NFI.

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