What does the PSF look like?

(2/15/94)

The PSPC has an intrinsic Gaussian resolution that appears independent of off-axis angle. It scales roughly as the inverse of $\sqrt{E}$ with a value of about 25 arcsec at 1 keV.

a broadening occurs, as the counter is focused for 1 keV photons; particularly for photons of greater energy, there will be additional penetration into the counter. The functional form is that of an exponential. Below 1 keV, the gaussian component is dominant.
the intrinsic scattering of the mirror (function = Lorentz)
the blurring due to off-axis photons
residual blur due to the wobble not being completely removed by the attitude solution (approximately +/- 5 arcsec). This term is a function of the roll angle.

The most recent discussion of the PSPC point spread function (and the PSFs for the HRI and WFC as well) can be found in "The ROSAT point spread functions and associates" (Boese 2000A&AS, 141, 507B). The figures below show the PSF for various combinations of energies and off-axis angles.

PSPC Pointing PSF density for E=1keV,off-axis angle = 0, 12, 24, 36, 48 and 57arcmin — PSPC Pointing PSF density for E=1keV, ϵ= 0, 12, 24, 36, 48 and 57arcmin (Figure 1 from Boese 2000, where ϵ is the off-axis angle of the source)

On-Axis PSPC Pointing PSF density for E= 0.1, 0.5, 0.9, 1.3, 1.7 and 2keV (Figure 2 from Boese 2000)

PSPC Pointing PSF density for off-axis angles = 30 arcmin, E= 0.1, 0.5, 0.9, 1.3, 1.7 and 2keV — PSPC Pointing PSF density for ϵ= 30 arcmin, E= 0.1, 0.5, 0.9, 1.3, 1.7 and 2keV (Figure 3 from Boese 2000, where ϵ is the off-axis angle of the source)

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This file was last modified on Friday, 12-Jun-2020 14:18:11 EDT