Diagnostic capability of FG/SP

Kiyoshi Ichimoto

NAOJ

Hinode workshop, 2007.12.8-10, Beijing

Contents:- Spectral windows of SOT- Available spectral lines and their Zeeman properties- Detection limit for the magnetic field w/ polarization sensitivity of SOT- Retrievability of magnetic field from NFI observables

SOT broadband filters

Field of view 218" × 109" (full FOV)

CCD 4k × 2k pixel (full FOV), shared with the NFI

Spatial Sampling 0.0541 arcsec/pixel (full resolution)

Spectral coverage

Center (nm) Width (nm) Line of interest Purpose

388.35 0.7 CN I Magnetic network imaging

396.85 0.3 Ca II H Chromospheric heating

430.50 0.8 CH I Magnetic elements

450.45 0.4 Blue continuum Temperature

555.05 0.4 Green continuum Temperature

668.40 0.4 Red continuum Temperature

Exposure time 0.03 - 0.8 sec (typical)

BFI

BFI

BFI

Contribution function of BFI continuum

log(5000)

Response function of BFI intensity from T/Tcourtesy Dr. Mats Carlsson

CH3883, CN4305 (G-band) formation height

S. V. Berdyugina etal., 2003,A&A 412, 513–527

Quiet region

sunspot

SOT narrowband filterField of view 328"×164" (unvignetted 264"×164")

CCD 4k×2k pixel (full FOV), shared with BFI

Spatial sampling 0.08 arcsec/pixel (full resolution)

Spectral resolution 0.009nm (90mÅ) at 630nm

Spectral windows (nm) and lines of interest

Center -range Lines geff Purpose

517.2 0.6 Mg I b 517.27 1.75 Dopplergrams and magnetograms

525.0 0.6 Fe I 524.71 2.00 PhotosphericmagnetogramsFe I 525.02 3.00

Fe I 525.06 1.50

557.6 0.6 Fe I 557.61 0.00 Photospheric Dopplergrams

589.6 0.6 Na I D 589.6 1.33 Very weak fields (scattering polarization)Chromospheric fields

630.0 0.6 Fe I 630.15 1.67 Photospheric magnetograms

Fe I 630.25 2.50

Ti I 630.38 0.92 Umbral magnetograms

656.3 0.6 H I 656.28 ~1.3? Chromosphreic structure

Exposure time 0.1 - 1.6 sec (typical)

NFI 517.27 (Mg b2)

NFI 525.02

NFI　 557.60

NFI　 589.60 Na D1

D1D2

NFI　 630.25

NFI　 656.27 H

MG1 5172.680 3P1 - 3S1 2.700 -.3800WI 1259.0 b2

NA1 5895.920 2S0.5 - 2P0.5 .000 -.1840MS 564.0*

H 1 6562.740 1 2S 0.5 2P 0.5 10.199 -.0606WI 4020.0

FE1 6302.503 5P1 - 5D0 3.686 -.6100CW 　 83.0

FE1 5250.207 5D0 - 7D1 .121 -4.4600CW 62.0

Zeeman patterns of NFI lines

10” 100” 1000” FOV

Time res.

1”0.1”Spatial res.

1sec

1min

Time span

1hr

1day

1week

10sec

1

# of wavelength (reliability)

Random noise(detection limit)

1min

1hr

1day

10min 4

2

64

16

0.01%

0.1%

1%

0.2” 0.4”

SOT/NFIfull image Ground SP

Ground FG magnetographSOT/SP

full scan

SOT performance

Resolution for energy element　～　 (x)2

SOTセミナー＠花山　 2004.12.7

dx=0.2”

(SOT)

dx=1”

(ground)

n = 0.5% n = 0.1% n = 0.1%

Detection limit

Bl (G) 8.5 1.7 1.7

Bt (G) 141 63 63

j (A) 1.2 x 109 5.2 x 108 2.6 x 109

(erg, l=104km) 1.3 x 1028 6.6 x 1027 1.3 x 1029

Accuracy

Bt (G, Bt=500G)

(deg., ” )

20 4 4

2.3 0.45 0.45

j (A, ” ) 1.6 x 108 3.3 x 107 3.3 x 108

erg) 2.4 x 1030

(N=1000)

4.8 x 1029

(N=1000)

1.5 x 1031

(N=500)

Detection limit and accuracy of magnetic field measurements-- rough comparison with ground-based observations --

Photon noise limited, FeI6302A line

S’ = XSX : polarimeter response matrix

Ground calibrationXr

-1S’ S”

on-boarddemodulation

SIncident Stokes vector

I’

modulatedintensity

STIncident topolarimeter

Telescope

ST = TS

S”reducedStokes vector

I”

CCDoutput

S’ SOT

product

CCD gain/darkI’’ = I’+

Polarization modulation

Measurement error: S

I’ = W ST

dark/gaincorrection

SrawSOT

raw data

Polarimeter response matrixX : true matrixXr

: matrix used in calibration

polarimeter response matrix

Sheet polarizer

window

(I,Q,U,V)

mask

FPP

Heliostat

ＳＯＴ polarization calibration before launch 2005.6 @Mitaka

incidentproductV

U

Q

I

xxxx

xxxx

xxxx

xxxx

V

U

Q

I

33231303

32221202

31211101

30201000

Using well-calibrated sheet polarizers (linear & circular), the polarimeter response matrices, X, of SP and all wavelength of NFI were determined with an accuracy below.

Accuracy:

0.3333 0.3333 0.25000.0010 0.0500 0.0067 0.00500.0010 0.0067 0.0500 0.00500.0010 0.0067 0.0067 0.0500

X <

SOT is cross-talk free at ~ 10-3 level

Diagonal elements tell about the sensitivity of the SOT to Q,U,V

Left 1.0000 0.2205 0.0187 -0.0047 0.0012 0.4813 0.0652 -0.0014 0.0001 0.0513 -0.4803 -0.0057 -0.0025 0.0032 -0.0046 0.5256

Right 1.0000 -0.2112 -0.0170 -0.0051 -0.0025 -0.4875 -0.0560 0.0022 -0.0001 -0.0426 0.4907 0.0060 0.0027 -0.0008 0.0042 -0.5301

Median Mueller matrix

x matrices at scan center; CCD image each element is scaled to median + tolerance, x00 (=1) is replaced by I-image

The x matrix can be regarded as constant in the CCD.

SP

X matrix over the CCD, 517280x1024

Example of FG/NFI

left: theta= -1.571deg. 1.0000 -0.2994 -0.0336 -0.0435 0.0009 -0.4544 0.0208 0.0045 -0.0009 0.0287 0.4478 0.0068 -0.0085 0.0318 -0.0134 0.5774

right: theta= -4.441deg. 1.0000 -0.2871 -0.0305 -0.0434 -0.0003 -0.4473 0.0653 0.0038 -0.0007 0.0738 0.4435 0.0061 -0.0077 0.0310 -0.0150 0.5718

1) Detection limit for circular and linear polarizations

is the photometric accuracy x33 and x11 are diagonal elements of X

11

33

/~

/~

xQ

xV

2) Polarization signals by Zeeman effect in a weak field

)()(' TII

max//

2

max2

222

'~

'

~

d

dIBgV

d

IdBGQ

eff

3) Thus detection limit for magnetic fields are given by

Line profile convoluted with the tunable filter profile

Detection limit of NFI for weak fields

)2(0

)2(1 GGG Difference of 2nd

moments of and-components

max

222211

2

max2

33//

/'

11~

/'

11~

dIdGxB

ddIgxB

eff

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Q

U

V

SOT modulation profiles from the measured PMU retardance

Wavelength (nm)

Retardation (wave)

517.3 6.682

525.0 6.572

589.6 5.762

630.2 5.344

656.3 5.110

Wavelength

(nm) geff

Ｇ

Pol. Sensitivity(diagonal element of X)

Detection limit for B(Gauss)

V QU Bl Bt

MgI 517.2 1.75 2.88 0.577 0.452 37 970

FeI 525.0 3.00 9.00 0.266 0.609 15 210

FeI 557.6 0.00 0.00 - - - -

NaI 589.6 1.33 1.33 0.633 0.297 21 1240

FeI 630.2 2.50 6.25 0.526 0.503 10 240

HI 656.3 1.33 1.33 0.402 0.073 78 >5000

Detection limit of FG for the weak magnetic fields,

= 0.001

Line

(A)

Usage Detec. limit B

= 0.1% (G)

Bl Bt

5172 Active region lower chrom. Vector mag.fields

Shutterless mode is preferable

37 970

5250 Vector mag.field in photosphere

Highest sensitivity to linear pol. with higher spatial resolution

15 210

5576 Photospheric Dopplergram - -

5896 Longitudinal meg.field in lower chromosphere

Prominence core imaging

21 1240

6302 Vector mag.field in photosphere

Umbral mag.field with TiI line

10 240

6563 Chromosphere/prominence imaging and Dopplergram

No sensitivity to linear pol.

78 >5000

Choice of a NFI line

NFI observables -- I(i), Q(i), U(i), V(i), i = 1,,, N

Physical quantities derived from the observables -- B field strength (G),

inclination (deg.), azimuth (deg), S Doppler shift (mA)

• fill factor =1• Other quantities responsible for line formation are assumed to be those in typical quiet sun.

An algorithm to derive the magnetic field from the NFI observables is tested.The algorithm is based on the least square using model Stokes profiles calculated beforehand

How well can we retrieve the magnetic field from the products (IQUV) of the NFI?

データ解析ワークショップ　 2004.12.20-23

Qpeak （ =90 ゜）

Polarization degree

Peak wavelength

I,Q,V Zeeman profiles against B

Vpeak （ =0 ゜）

I

Q

V

The method to derive the magnetic field vector from the NFI observables depends on the number of observed wavelength points.

N = 1: 1-dimensional LUT for V/I Bl, Q/I Bt individually

N = 2: Rotate the frame to make U=0 (ignore MO effect)

+ search for the best fitting to model observable in (B, , S) space

N > 3: Initial guess with cos-fit algorithm

+ rotate the frame to make U~0

+ search for the best fitting to model observable in (B, , S) sub space

To test the performance of the algorithm, numerical simulations are made using ‘artificial sample observables’ (1000 sets) calculated with an atmospheric model with random physical parameters in a range of

0 < B < 3000 G 0 < < 180 deg.-90 < < +90 deg.-90 < S < +90 mA

No Doppler info.

N = 1 at dl = -80mA, Simulation result

Sample observable, 1000pointsB < 2000G B >2000G

|S| < 60mA black blue

|S| > 60mA green red

alternative method: - ignoring MO effect - search entire (S, B, ) space

B < 2000G B >2000G

|S| < 60mA black blue

|S| > 60mA green red

N = 2 at d = [-80, 80] mA, simulation result

N = 4 at d = [-110, -70, 70,110] mA, simulation resultB < 2000G B >2000G

|S| < 60mA black blue

|S| > 60mA green redNon-uniform wavelength sampling

Diagnostics using SP data

Zeeman effect produces polarization in spectral lines

Obtain magnetic field vectors and motions in solar atmosphere.

slit

Stokes profiles fitting program

- Milen-Eddington fitting for Hinode SP Data analysis session..

- SIR fitting programs

SP data contains much more information on the structures of the solar atmosphere..