1 On-orbit SOT performance Kiyoshi Ichimoto and SOT-team Hinode workshop, , 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, 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. Sun’s diameter ～ 1,400,000 km 10,000 km

4 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 km 0.2 arcsec 4000km Close-up of granules in G-band (430nm)

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

6 FW1 FW2 VLS-close 0.031”rms 0.028”rms 0.032”rms 0.036”rms RSS=0.142”(3  ) 0.5s RSS=0.128”(3  ) VLS-open 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 Accuracy:  QUV/Ic ~ (5s integ.)  I/Ic ~ 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 absolute line shift Q=75 I-profile after flat correction Two remarks on the SP feature

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

10 G-band focus position history - 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. eclipse

11 NGT DAY+10minNGT-3min NGT 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 eclipse The cause of the loss of throughput is not identified. No science impact at this point.

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 Telescope temperature is now stable. No evidence of significant progress of contamination in OTA. eclipse

15 TF Bubble in the FOV TF6 TF5 ~1A Tunable elements which carries the bubbles are identified. Tunable filter bubble big bubble 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 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 Possible tuning w/o moving bubble elements The separation can not be free to prevent the motion of particular elements.

19 Wavelength (nm)g eff Ｇ Pol. Sensitivity (diag.elem. of X) Detection limit of B (  = 0.001, Gauss)  blocking TF5-8 (mA) VQU Optimized TF specified BlBl BtBt BlBl BtBt MgI FeI FeI NaI FeI HI > > Detection limit of NFI for weak magnetic fields 2 nd moments of  and  -components I’: line profiles convoluted by TF transmission curve 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  =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. 2007/11/22 K.I.

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

21 FeI 5576 Dopplergram, , A

22 NaI D1 Dopp./Mag , A

23 FeI 5250A IQUV , /+0.136A

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

25 Ha Doppler , H  A I Dopp.

Test of New Shuttered IV New OBS_ID 61: takes 5.9 sec V noise = 6.5 DN, S/N >  +24 DN display Old OBS_ID 2: takes 3.9 sec V noise = 7.7 DN, S/N ~  +24 DN display 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

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.