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

bx42_apr25 calibration series

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.

bx51_apr25 calibration series

Elipticity of the corecalibration 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.

averaged core cross sectionscalibration series

bx42_apr25 bx02_apr23 bx51_apr25

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

x-cross sections y-cross sections

Al-K

C-K

Ag-L

Al-K

C-K

Ag-L

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.

SXT flare frame

8-MAY-00 at 10:50:21Deconvolved image

SXT flare frame (Log10 scale) Deconvolved image (Log10 scale)

Example of deconvolution of SXT Flare images

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