Data processing of filament observations using a tunable H-a filter

Hyungmin Park1,3, Jongchul Chae2,

Yong-Jae Moon3, Young-Deuk Park3

1Dept. of Astronomy and Space Science, Chungnam National University2SEES, Seoul National University

3Korea Astronomy and Space Science Institute

contents

• Introduction

• Basic data processing

• Additional data processing

• Further works

Introduction

• H-a observation– Chromosphere– Active Regions, Filaments, Flares…– Specific wavelength : H-a centerline, wing– Limitation

• Multiwavelength observations– Using two or more wavelength– Filter Scanning (Imaging Spectroscopy)– Can infer the temporal changes in the morphology,

brightness and so on

Two types for imaging spectroscopy

wavelength (scan)

space

space

wavelength

space(scan)

① ② ③

①

②

③

space

Data

• Aug 4, 2004, BBSO• 10 inch telescope (FOV 384”)• 5 wavelengths

– -0.65Å, -0.35Å, -0.05Å, +0.25Å, +0.55Å– Zeiss Filter (0.25Å)– About ~20(~4) sec

• Fast CCD Camera (30fps)• Using frame selection method• Filament

Basic data processing

• Classification of each wavelength data

• Subtraction of Dark/Bias

• Masking

• Flat fielding

• Fourier filtering

• Align dust

Raw data

Masking

Flat-fielding (Chae, 2004)

Align dust position

Fourier filtering

Filtergram Images-0.65Å -0.35Å -0.05Å

+0.25Å +0.55Å

Additional data processing

• Constructing Contrast Data Cube– Image Enhancement

• Using deconvolution

– Calculation of Contrast– Data Registration(destretching)– Align Different Wavelengths

• Subsonic filtering

Calculation of contrast

• Uncorrected Contrast

• Corrected Contrast

• Corrected reference intensity

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Subtracting background

Data Registration

• Make successive contrast images at the same wavelength

• Determine relative displacement of image files to reference image

• Correct relative displacement– Shifted back all images

• Image destretching• Repeated for every set of images taken at diffe

rent wavelengths

Subsonic filtering• Remove noise

– Oscillation• Cut-off speed

– 35km/s– Larger than the

transverse motion inside a quiescent prominence

Effect of image processing

Future work

• Additional data processing– Wavelength calibration

• Data analysis– Cloud model fitting– Get physical parameters

• Optical thickness• Line of sight velocity• Doppler Width• Source Function