D. E. McKenzie (Montana State University), S. Gburek (Space Research Centre, Polish Academy of Sciences), L. W. Acton, P. C. Martens (Montana State University) The Point Spread Function of the Yohkoh Soft X-ray Telescope Poster preparation for AAS meeting
Abstract The point spread function (PSF) of the Yohkoh solar observatory's SoftX-ray Telescope has two primary components, a sharply defined core and adiffuse wing due to photon scattering. Because the extent of the PSF issignificantly wider than a single pixel, its characterization is usefulfor improvement of the quality of the SXT images. We will present resultsfrom analyses of the two PSF components, and demonstrate our best model ofthe core and scattering wing of the SXT point spread function. An exampleof PSF deconvolution to remove the effects of photon scattering will begiven
Core part of the SXT PSF Properties: Size – about 5 pixels from the peak FWHM – approx. 1.5 pixels Depends on wavelength, position on the CCD
Calibration series to consider BX42_APR25 49 C K (0.28 keV/44.7 A) Best_Defoc XY Scan -> X,-11,500 to -2,500; Y, -6,500 to 2,500; Step 1,500 BX02_APR23 49 Al K (1.49 keV/8.34 A) Best_Defoc XY Scan -> X,-11,500 to -2,500; Y, -6,500 to 2,500 Step 1,500 BX51_APR25 49 Ag L (3.00 keV/4.16 A) Best_Defoc XY Scan -> X,-11,500 to -2,500; Y, -6,500 to 2,500; Step 1,500 Could be also BX21_APR24 49 C K Best_Defoc XY Scan -> X,-11,500 to -2,500; Y, -6,500 to 2,500; Step 1,500
bx02_apr23 calibration series The image above shows 49 images of bx01_apr23 ground calibration series. Enlarged contour plots of their peak portions in the image bellow.
Elipticity of the core calibration series bx42_apr25 bx02_apr23 bx51_apr25 The PSF core gets elliptically deformed with the distance from the CCD center. In the CCD corners can be even double peaked.
calibration series bx42_apr25 bx02_apr23 bx51_apr25 averaged core cross sections Solid line peak x-cross sections (upper row) and y-cross sections (the bottom row) for average PSF core for WSMR calibration series. The average PSF shape was determined from images 7-49 for each of (mentioned above) series respectively. Error bars show absolute errors for the selected images
Comparison of cross sections of averaged PSF core for different energies Ag-L Ag-L C-K C-K Al-K Al-K x-cross sections y-cross sections
Core aplications Aplications: Deconvolution of the SXT Flare images, mainly in horizontal belt shown to the left where eliptical deformation of the core PSF part is small. Above, a coverage map of the CCD detector surface by full resolution SXT frames. Gray intensity says how many times a given pixel was captured within a full resolution frame during year 2000.
Example of deconvolution of SXT Flare images SXT flare frame 8-MAY-00 at 10:50:21 Deconvolved image SXT flare frame (Log10 scale) Deconvolved image (Log10 scale)
PSF approximation from steepest descent method Calibration beam seen in Al.-K line Deconvolved PSF PSF cross sections (x-cross section in the left panel, to the right y-cross section. Thin solid line – cross sections of the PSF found by steepest descents method Thick solid line – cross sections of the calibration beam Diamonds – deconvolved PSF cross-sections