Pointing Stability of Hinode andRequirements for SOLAR-C (Option-B)
Y. Masada, Y. Katsukawa (NAOJ)、
T. Shimizu (ISAS/JAXA), K. Ichimoto (Kyoto U.)
Solar-C Science Definition Meeting 2 @ISAS/JAXA, 2010, March 10

Purpose:
Toward next Solar-C satellite with higher pointing-stability,
Report “on-orbit” performance of image stabilizing
system on-board Hinode satellite- Identify major sources for disturbances- Asses the achievement of Hinode Satellite- Raise Issues in realizing Solar-C (Option-B)

Contents:
1. Analysis on jitter ambient in the telemetry data of UFSS and IRU[low frequency regime (10-4 Hz < f < 10-1 Hz)]
2. Analysis on the jitter ambient from SOT with CT servo on/off[high frequency regime (10-2 Hz < f < 200 Hz)]
3. Requirements for Solar-C V.S. Performance of Hinode on-orbit

Image Stabilizing System on-board Hinode
Position Control Sensors and Correlation Tracker on board Hinode・Ultra Fine Sun Sensor [UFSS (-A,-B)], (10-5 Hz < f < 10-1 Hz)
・Inertia Reference Unit [IRU (-A, -B1)], (10-2 Hz < f < 10-1 Hz)
・Correlation Tracker [SOT/CT], (10-2 Hz < f < 290 Hz)

・Specify the dominant disturbances in the jitter by Fourier Analysis
・Evaluate the amplitude of major disturbances (= Pointing Error)
Y

UFSS-A
CT

UFSS-BZ

IRU-B1※）IRU-A : FRIG floated rate integrating
gyro (made by JAE)
IRU-B1: TDG tuned dry gyro
(made by MPC)

IRU-AX1. Diagnostic data of UFSS/IRUZTime Profile: Telemetry data of UFSS and IRU
Amplitude (arcsec)

32X

X-axisY-axis

UFSS-A+B

10-1-2-3
00:00

02:00

04:00

06:00Start Time (17-Dec-07 22:41:03)

Amplitude (arcsec)

20X-axis
Y-axisIRU-A
100-10-20

10:00

12:00

14:00

Start Time (20-Apr-09 08:41:05)

Y

16:00

Power Spectrum Density for Jitter Disturbances (UFSS)
5x10-3 Hz= 200 sec

UFSS-A

UFSS-B

5x10-3 Hz= 200 sec cycle
0.1 Hz0.1 Hzorbital modulations

X-axisorbital modulations

Y-axisX-axisY-axisFeatures and Major Sources for Disturbances in the jitter of UFSS:- f ~ 0.1 Hz : position sensor can control the disturbances with f < 0.1 Hz- f < 10-3 Hz: orbital modulation + its higher frequency (2f,4f,6f …)[f ~ 5x10-3 Hz: unidentified (but, the contribution to the jitter is small)]Power Spectrum Density for Jitter Disturbances (IRU)
IRU-A

orb
ital

mo

dul

0.1 Hzatio

ns

X-axisIRU-B1orb

ital

0.1 Hz

mo

dul
atio

ns
X-axisY-axisY-axisFeatures and Major Sources for Disturbances in the jitter of IRU:
- f ~ 0.1 Hz : position sensor can control the disturbances with f < 0.1 Hz- f < 10-3 Hz: orbital modulation + its higher frequency (2f,4f,6f …)[no peak around f ~ 5x10-3 Hz which can be seen in UFSS data]
The characters of PSD in the case IRU are almost same as that in UFSS

Secular variation of the pointing error
2007

2008

2009 （A.D.）(IRU-A)

Evolution of Orbital modulation(10-4 Hz < f < 10-3 Hz)

modulation around 0.1Hz(10-2 Hz < f < 100 Hz)

Start Time (May 2007)

Characteristics in the long term variation:- There is a seasonal variation in the orbital modulation as expected.
: shade term (Apr. to Aug.) → large error, but it become smaller during Oct.-Jan.
- The modulation around 0.1 Hz increases secularly (we don’t know why...).

SOT Diagnostic data

Fourier Power Spectrum: SOT/CT - lower frequency band
Polarization peaks due topolarization modulator
X-axisY-axis

0.625Hz

1.25Hz
2.5Hz

CT Servo ON

X-axisY-axisCT Servo OFF

0.625Hz

1.25HzFeatures:- the disturbances are reduced
clearly by CT in f < 10 Hz- Peaks around 1.0 Hz are dueto the polarization modulator
rotating with period 1.6 sec
・ 0.625 Hz
・ 1.25 Hz (Stokes V)・ 2.5 Hz (Stokes Q and U)※ Polarization modulator which
is located in the optical pathgenerates the modulations ofthe circular and linear
polarization signals

Fourier Power Spectrum: SOT/CT - higher frequency band
IRU-SA (113Hz)

Cross over frequency

CT Servo ON

IRU-B (155Hz)
X-axisY-axisFeatures:- 40-290Hz → a lot of peaks are
generated due to the external
disturbances (momentum wheel)- The peak value of the error
is typically 10-2 [arcsec]
20Hz (= cross over frequency)

IRU-SA (113Hz) IRU-B (155Hz)

CT Servo OFFX-axis
Y-axis

CT servo off

Cross over frequency

PSD [arcsec2/Hz]

SOT/CT performance on-orbit: Excellent !

CT servo on- The disturbances are reduced drastically at the lower frequency band
than 20Hz (= cross over frequency).
SOT/CT show, even on-orbit, the performance expected before launching.

Requirements for Solar-CV.S.
Performance of Hinode on-orbit- Asses the achievement of Hinode Satellite- Raise Issues in realizing Solar-C (Option-B)

Required Ability for Hinode and its Performance on-orbit
UFSS(for pointing error)
IRUCT1）Pointing Error in X-axis is used for CT
2）Acceptable level is the 1/3 of requirements
and is filled by the color

UFSSperformance

Hinode SOT
Hinode EIS

IRU
performance
CT (servo on)

CT (servo off)

(Required)

Hinode XRTThe performance of image stabilization system on-board Hinodeis excellent and meets the required ability even on-orbit.

Requirements for Solar-C and Performance of Hinode on-orbit(for pointing error)

UFSSIRU

CT1）Pointing Error in X-axis is used for CT2）Acceptable level is the 1/3 of requirements
and is filled by the colorUFSS
performance
IRU
Solar-C: UV-Vis-NIR
Solar-C: VUV/EUV IRU
Solar-C: X-ray (GI)performance

CT (servo off)

(Required)

Solar-C: X-ray (NI)

※GI: Grazing Incidence
NI: Normal Incidence

CT (servo on)

Issues:The performance of Hinode around 0.1 Hz does not meet the requirement for X-ray (NI)The performance of Hinode around 100 Hz does not meet the ability for UV-Vis-NIR

Requirements for Solar-C and Performance of Hinode on-orbit
UFSSIRUCT1）Pointing Error in X-axis is used for CT
2）Acceptable level is the 1/3 of requirements
and is filled by the color

UFSSperformance

IRU

IRU
Solar-C: UV-Vis-NIR performance
Solar-C: VUV/EUV
Solar-C: X-ray (GI)

(Required)

Solar-C: X-ray (NI)CT (servo off)

CT (servo on)Requirements for Solar-C and Performance of Hinode on-orbit
UFSS
IRU

CT1）Pointing Error in X-axis is used for CT
2）Acceptable level is the 1/3 of requirements
and is filled by the color

UFSS
performance

IRU

IRU
Solar-C: UV-Vis-NIR performance
Solar-C: VUV/EUV
Solar-C: X-ray (GI)CT (servo on)(Required)

Solar-C: X-ray (NI)CT (servo off)

If UV spectrograph with 0.2” spatial resolution is assumed, the required ability for
VUV/EUV become more severe (0.3 arcsec → 0.05 arcsec).

Summary: Toward Solar-C with required ability for Option-B
In the band f > 20Hz, we should reduce the disturbances generated by MW orextend the cross over frequency up to 300 Hz in order to meets the requirement.
The major disturbance source in UFSS/IRU is the orbital modulationsin the band f < 10-3Hz. They are generated due to the change of thermal
environment, not due to the characteristics of the position control sensors.

We should consider seriously the thermal structure of Solar-C
In the band 0.01Hz < f < 1Hz, the performance meets the required abilities
for UV-Vis-NIR, VUV/EUV and X-ray (GI) at least, but not for X-ray (NI).
CT would be needed for X-ray (NI) with required ability
CT would be needed for UV spectrograph with 0.2” spatial resolution

The disturbances in ~ 0.1 Hz seems to have serious impacts on Solar-C.
It must be reduced in designing the position control sensor for Solar-C.

Please keep this viewgraph in your mind !
UFSSIRUCT1）Pointing Error in X-axis is used for CT2）Acceptable level is the 1/3 of requirements
and is filled by the color

UFSSperformance

IRU

IRU
Solar-C: UV-Vis-NIR performance
Solar-C: VUV/EUV
Solar-C: X-ray (GI)Solar-C: X-ray (NI)CT (servo off)

CT (servo on)when you explore the science target for Solar-C

Appendix

Instruments on board Hinode and Data Sets
Position Control Sensors and Correlation Tracker on board Hinode・Ultra Fine Sun Sensor [UFSS (-A,-B)], (10-5 Hz < f < 10-1 Hz)
・Inertia Reference Unit [IRU (-A, -B1)], (10-2 Hz < f < 10-1 Hz)
・Correlation Tracker [SOT/CT], (10-2 Hz < f < 290 Hz)

We analyze the jitter in telemetry date of UFSS, IRU and diagnostic data of SOT/CT
UFSS, IRU:
- 40 data sets [from November 2006 to April 2009 (full disk only)]- Sampling: 0.5 sec (successive data more than 9 hours)- drift component is removed (by using the linear fitting)
SOT/CT:- diagnostic data of CT servo on/off [focus on Dec. 2007]- Sampling: 580 Hz (df = 0.5 Hz for averaging)・Specify the distinguished peak from Fourier Power Spectrum (PSD)
・Evaluate the amplitude of the major disturbances (= Pointing Error)※）IRU-A : FRIG floated rate integrating gyro (made by JAE),
IRU-B1: TDG tuned dry gyro (made by MPC)

Pointing Error (UFSS, IRU)
UFSS-A+B

IRU-A

Xaxis

Xaxis

Yaxis

Yaxis

OrbitalperiodOrbitalperiodresonances

resonances

Evaluation Methods for Disturbances- Thick line：By using high pass filter, we integrate PSD in the lower frequency regime- Symbol：By picking the distinguished peak from PSD up, we integrate the peak value
around peak frequency

Pointing error with high pass filter gives the upper limit of the error

Short term variation of higher frequency peaks
Short term variation of higher frequency peaks around 100Hz (t < 20sec)

10-2
Pointing Error (arcsec)~ 160 Hz~ 120 Hz~ 100 Hz~ 60 Hz10-1~ 260 Hz- no remarkable variation in short termLong term variation for pointing error in CT Servo oﬀ

X-axisY-axis20061027

20061108

20071215

20071216

20070316

PSD from diagnostic data in CT servo oﬀ (100sec data)

Ex = 0.032 [arcsec]
Ey = 0.045 [arcsec]

20061108

Secular swing for the disturbances in the higher frequency
Evolution of high frequency peaks during 2006 to 2009
Reference date~ 160 Hz
Now analyzing thedata obtained in 2010

~ 120 Hz~ 260 Hz~ 100 Hz~ 60 Hz~ 180 Hz(2007)(2008)(2009)

・Higher frequency disturbances tend to increase secularly.
・The peaks around 150Hz (due to IRU) and 180Hz swing remarkably.

Secular swing for the disturbances in the lower frequency

X-axis (0.05-0.3Hz)
Y-axis (0.05-0.3Hz)

X-axis (0.6-0.75Hz)

Y-axis (0.6-0.75Hz)(2007)

・There is no significant secular variation in lower frequency band.

Comment on Solar-C VUV/EUVUV spectrograph in Solar-C can really achieve 0.2” resolution ?
UV spectrograph

Normalized intensity

Solar-C: UV-Vis-NIR
Solar-C: VUV/EUV
Solar-C: X-ray (GI)Solar-C: X-ray (NI)

UFSS

IRU
CT (servo off)
CT (servo on)(arcsec)

We need CT in UV spectrograph for realizing 0.2” pointing resolution

Appendix 2：Data Sets (UFSS/IRU)

2008-4-22UFSS-A: (2008-4-22)

25

UFSS-B: (2008-4-22)

26

UFSS-A+B: (2008-4-22)

27

IRU-A: (2008-4-22)

28

IRU-B1: (2008-4-22)

29

2008-12-20

UFSS-A: (2008-12-20)

31

UFSS-B: (2008-12-20)

32

UFSS-A+B: (2008-12-20)

33

IRU-A: (2008-12-20)

34

IRU-B1: (2008-12-20)

35

Appendix 3：data sets (SOT/CT)

Summary of data analyzed
Data Set 1

Data Set 2

Data Set 3

on/offservo onservo off

servo onservo off

servo onservo offDate

2006/10/31

2006/10/27

2007/12/15

2007/12/15

2007/12/16

2007/12/16

Td [sec]

1687

256

1965

30.01724

24.1

Δf1

[Hz]

0.5

0.5

0.5

0.5

0.50.5

Δf2 [Hz]

0.025

0.025

0.025

0.025

Td ・・・duration of data
Δf1 ・・・frequency resolution for analyzing higher frequency bandΔf2 ・・・frequency resolution for analyzing lower frequency bandData Set 1

Δf = 0.5Hz

IRU-A (113Hz)

Δf = 0.5Hz

Figure 1: normal plot

IRU-B (155Hz)(20061027)

Servo off

(20061031)

Servo on(20061027)

Servo off

Δf = 0.5Hz(20061031)

Servo onΔf = 0.5Hz

Figure 2: logarithm plot of Fig.1

Δf = 0.025Hz

Polarization peak 1 : 0.625Hz
Polarization peak 2 : 1.25Hz
Polarization peak 3 : 2.5Hz

Δf = 0.025Hz

Figure 3: low frequency regime of Fig.1(20061027)

Servo off

(20061031)

Servo on

Figure 4:

Bode plot

G = 20log10(Aon/Aoff)
Aon: amplitude in servo on
Aoff: amplitude in servo off
G: GainData Set 2

Servo off

Δf = 0.5Hz(20071215)(20071215)

Servo onΔf = 0.5Hz

Figure 5: Other date (meanings are same as Fig.1)

Servo off

Δf = 0.5Hz(20071215)(20071215)

Servo onΔf = 0.5Hz

Figure 6: Other date (meanings are same as Fig.2)

Figure 7:

Bode plot

G = 20log10(Aon/Aoff)
Aon: amplitude in servo on
Aoff: amplitude in servo off
G: GainData Set 3

Servo off

Δf = 0.5Hz(20071216)(20071216)

Servo onΔf = 0.5Hz

Figure 8: Other date (meanings are same as Fig.1)

Δf = 0.5Hz

Δf = 0.5Hz

Servo on(20071216)

Servo off

(20071216)

Figure 9: Other date (meanings are same as Fig.1)

Figure10:(Bode plot)G = 20log10(Aon/Aoff)
Aon: amplitude in servo on
Aoff: amplitude in servo off
G: Gain