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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

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Diagnostic capability of fg sp

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)

SOT broadband filters






Response function of BFI intensity from DT/T

courtesy Dr. Mats Carlsson


CH3883, CN4305 (G-band) formation height

Quiet region

S. V. Berdyugina etal., 2003,

A&A 412, 513–527

sunspot


Sot narrowband filter

Field 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

l-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

Photospheric

magnetograms

Fe 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)

SOT narrowband filter




Nfi 557 60
NFI557.60


Nfi 589 60 na d1
NFI589.60 Na D1

D2

D1


Nfi 630 25
NFI630.25


Nfi 656 27 h a
NFI656.27 Ha


Zeeman patterns of NFI lines

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

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

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

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


Time res.

# of wavelength

(reliability)

1sec

64

10sec

16

1min

10min

4

2

1hr

1

1day

FOV

10”

100”

1000”

Spatial res.

1”

0.4”

0.2”

0.1”

1min

1%

1hr

0.1%

1day

1week

0.01%

Random noise

(detection limit)

Time span

SOT performance

SOT/NFI

full image

Ground SP

Ground FG magnetograph

SOT/SP

full scan

Resolution for energy element ~ e (Dx)2


Detection limit and accuracy of magnetic field measurements

-- rough comparison with ground-based observations --

Photon noise limited, FeI6302A line

SOTセミナー@花山 2004.12.7


Polarimeter response matrix
polarimeter response matrix

CCD

gain/dark

I’’ = a I’+b

ST

Incident to

polarimeter

Polarization modulation

S

Incident

Stokes

vector

I”

CCD

output

I’

modulated

intensity

Telescope

ST = TS

I’ = W ST

on-board

demodulation

Sraw

SOT

raw data

Measurement

error: DS

S’

SOT

product

S”

reduced

Stokes

vector

dark/gain

correction

Polarimeter response matrix

X : true matrix

Xr: matrix used in calibration

Ground

calibration

Xr-1S’ S”

S’ = XS

X : polarimeter response matrix


SOT polarization calibration before launch

2005.6 @Mitaka

Heliostat

mask

window

(I,Q,U,V)

Sheet polarizer

FPP

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 0.2500

0.0010 0.0500 0.0067 0.0050

0.0010 0.0067 0.0500 0.0050

0.0010 0.0067 0.0067 0.0500

DX <

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

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


SP

x matrices at scan center; CCD image

each element is scaled to median + tolerance, x00 (=1) is replaced by I-image

Median Mueller matrix

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

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


Example of FG/NFI

X matrix over the CCD, 5172

80x1024

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


Detection limit of NFI for weak fields

1) Detection limit for circular and linear polarizations

e is the photometric accuracy

x33and x11 are diagonal elements of X

2) Polarization signals by Zeeman effect in a weak field

Line profile convoluted with the tunable filter profile

Difference of 2nd moments of s and p-components

3) Thus detection limit for magnetic fields are given by


SOT modulation profiles from the measured PMU retardance

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

Q

V

U




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

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

  • Physical quantities derived from the observables

  • -- B field strength (G),

  • g inclination (deg.),

  • c 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


I,Q,V Zeeman profiles against B products (IQUV) of the NFI?

Polarization degree

Vpeak (g =0゜)

I

Qpeak (g =90゜)

Q

Peak wavelength

V

データ解析ワークショップ 2004.12.20-23


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, g, 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, g, 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 <g< 180 deg.

    • -90 <c< +90 deg.

    • -90 < S < +90 mA


N = 1 observables depends on the number of observed wavelength points.at dl = -80mA, Simulation result

No Doppler info.

Sample observable, 1000points


N = 2 observables depends on the number of observed wavelength points.at dl = [-80, 80] mA, simulation result

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


N = 4 observables depends on the number of observed wavelength points.at dl = [-110, -70, 70,110] mA, simulation result

Non-uniform wavelength sampling


Diagnostics using sp data
Diagnostics using SP data observables depends on the number of observed wavelength points.

slit

Obtain magnetic field vectors and motions in solar atmosphere.

Zeeman effect produces polarization in spectral lines


Stokes profiles fitting program observables depends on the number of observed wavelength points.

- 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..


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