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Comparison of FG and SP data from Sun test

Comparison of FG and SP data from Sun test. M. Kubo (JAXA/ISAS), K. Ichimito, Y. Katsukawa (NAOJ), and SOT-team. Simultaneous observation with FG and SP. We simultaneously observe a sunspot with FG Shutterless IQUV and SP profiles in Sun light test at NAOJ.

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Comparison of FG and SP data from Sun test

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  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 01:01:29 - 01:02:31UT • - wavelength range: Fe I 6302.5ű240mÅ • - wavelength sampling: 40mÅ step • Spectro-polarimeter(SP) • - 2004/08/20 00:56:19 - 01:17:46UT • (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] (1pixel=21.5mÅ)

  4. Spatial distribution of IQUV at each wavelength Stokes I -240mÅ -120 0 +120 +240 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 -240mÅ -120 0 +120 +240 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 -240mÅ -120 0 +120 +240 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 -240mÅ -120 0 +120 +240 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 Red：normalized by red wing Blue：normalized 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 Red：normalized by red wing Blue：normalized 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 Red：normalized by red wing Blue：normalized by blue wing

  12. Summary • Stokes IQUV profiles of FG have rough agreement to • SP IQUVprofiles 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

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