M' Kubo JAXAISAS,

1
Comparison of FG and SP data from Sun test

• M. Kubo (JAXA/ISAS),
• K. Ichimito, Y. Katsukawa (NAOJ),
• and
• SOT-team

2
Simultaneous observation with FG and SP

• We simultaneously observe a sunspot with
• FG Shutterless IQUV and SP profiles
• in Sun light test at NAOJ.
• Filtergraph (FG Shutterless IQUV)
• - 2004/08/20 010129 - 010231UT
• - wavelength range Fe I 6302.5Å240mÅ
• - wavelength sampling 40mÅ step
• Spectro-polarimeter(SP)
• - 2004/08/20 005619 - 011746UT
• (20 minutes for obtaining one map)
• - spectral profile of Fe I 6302.5Å (and Fe I
  6301.5Å )
• - wavelength sampling (1pixel) 21.5mÅ

FG (-240mÅ)
SP (-240mÅ)
Time of FG observation (13 wavelengths)
20 min
3
Data processing for FG and SP
Stokes I (SP data)
1. Polarization calibration for FG and SP -
X-matrices of FG and SP are presented in
previous talks. - We do not calibrate
polarization induced by optics outside
SOT. 2. Determination of an absolute wavelength
of SP profiles from the telluric line
(6302.0Å) (FG wavelengths are referred to
fits header values.) 3. Convolution of SP
profiles with a transmission profile of FG
Tunable Filter ? SP profiles are modified to
the profiles observed with FG. 4.
Image co-alignment between FG - SP and
between FG images with various wavelengths
using image cross-correlation
Fe I 6302.5Å
telluric lines
Fe I 6301.5Å
wavelength pixel (1pixel21.5mÅ)
4
Spatial distribution of IQUV at each wavelength
Stokes I
0
240
-240mÅ
120
-120
FG
At first, we compare FG IQUV images with SP maps
at each wavelength same as the FG images.
SP
5
Spatial distribution of IQUV at each wavelength
Stokes V
0
240
-240mÅ
120
-120
FG

• Line center of V profile
• (zero-cross)for FG is
• shifted about -40mÅ to the
• line center of SP
• (absolute wavelength).
• Stokes V images of
• FG and SP have
• similar patterns.

SP
6
Spatial distribution of IQUV at each wavelength
Stokes Q
0
240
-240mÅ
120
-120
FG
Stokes Q and U images of FG also have
similar patterns of SP maps.
SP
7
Spatial distribution of IQUV at each wavelength
Stokes U
0
240
-240mÅ
120
-120
FG
Stokes Q and U images of FG also have
similar patterns of SP maps.
SP
8
Comparison of FG and SP profiles

• We compare FG and SP profiles for umbra,
• penumbra, and quiet region.
• FG and SP profiles are averaged over the sky
• blue boxes to reduce influence on image
• motion due to seeing and alignment error
• Line centers of FG and SP are determined by
• second-order polynomial fitting. FG profiles
  are
• shifted to align the line centers of SP.

FG (-240mÅ)
SP (-240mÅ)
Stokes I
umbra
penumbra
?FG -SP
quiet region
alignment result
Wavelength mÅ
9
FG and SP profiles (penumbra)
I
Q

• FG and SP IQUV profiles
• are rough agreement as
• a whole, but their difference
• is large at some points.
• The difference of I is larger
• than Q, U, and V. This would
• be due to variation of light
• level during the observation.

U
V
?shifted FG profile, -SP profile Rednormalized
by red wing Bluenormalized by blue wing
10
FG and SP profiles (quiet region)
I
Q

• FG IQUV data also have
• similar shapes to SP profiles
• in the quiet region.
• Q, U, and V profiles of
• SP and FG are well fitted
• although degree of polarization
• is very small in the quiet region.

U
V
?shifted FG profile, -SP profile Rednormalized
by red wing Bluenormalized by blue wing
11
FG and SP profiles (umbra)
I
Q

• FG IQUV data also have
• similar shapes to SP profiles
• in the umbra.
• A scatter of FG data is larger
• than that in the penumbra or
• the quiet region. The umbral
• profiles are easy to be affected
• by surroundings because the
• umbra is darker than the
• surroundings.
• The deviation of I is large on
• red-side. However the absolute
• deviation is small, because the
• profiles are normalized by
• dark local continuum.

U
V
?shifted FG profile, -SP profile Rednormalized
by red wing Bluenormalized by blue wing
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Summary

• Stokes IQUV profiles of FG have rough agreement
  to
• SP IQUV profiles in umbra, penumbra, and quiet
  region.
• But their deviation is large at some points.
• The deviation of I is larger than that of Q, U,
  and V.
• The difference between FG and SP profiles would
  be due to
• - false modulation signal caused by a poor
  seeing condition
• - variation of light level
• seeing condition, intensity ripple of FG
  tunable filter
• (Removal of the intensity ripple were
  represented by Katsukawa-san.)
• - time difference
• - alignment error