Glossary#

CCD#: Charge-Coupled Device — the XRT’s imaging detector, where photons are converted into electrons and then digitized into data numbers (DN).
Channel#: A specific configuration of the XRT instrument, defined by the combination of filters in both filter wheels. Each channel affects the telescope’s sensitivity and spectral response.
Contamination (related to the XRT)#: Refers to the gradual accumulation of material on the CCD and focal plane filters (FPFs), which reduces instrument throughput. This time-dependent degradation impacts effective area calculations and must be accounted for in data analysis. Refer to Section 2.5.3 Contamination in the SolarSoft XRT Analysis Guide for more information.
Deconvolution#: A numerical image processing technique used to correct for the blurring caused by the telescope’s Point Spread Function (PSF), improving sharpness and visibility of fine structures.
DEM#: Differential Emission Measure (DEM) — a function that describes the distribution of plasma as a function of temperature along the line of sight. XRTpy will support DEM modeling in future versions.
DN#: Data Number (DN) — the digital value recorded by the CCD, representing the detected photon flux, usually in DN s⁻¹.
Effective Area#: A measure of the telescope’s throughput for a given channel, combining geometric area with efficiencies of mirrors, filters, and detector — all affected by contamination and aging.
Emission Measure#: A quantity proportional to the square of the electron density integrated along the line of sight, used to infer the amount of emitting plasma.
FilterRatio Method#: A technique used to estimate plasma temperature and emission measure by comparing the intensity of X-ray images taken with two different XRT filters. Assumes an isothermal plasma and relies on accurate temperature response functions.
Light Leak#: Refers to periodic increases in visible stray light contamination in XRT images, likely caused by a pinhole or defect in the entrance filter. This results in unwanted signal contributions, particularly affecting synoptic composites and thin filters. Users are encouraged to consult the SolarSoft XRT Analysis Guide (see Table 2.2) and use xrtpy.image_correction.remove_lightleak for correction.
PSF#: Point Spread Function — describes the response of the telescope to a point source of light. In XRTpy, it is used in deconvolution routines to sharpen images.
Solar Emission Spectra#: Emission spectra produced by solar plasma across a range of temperatures, calculated using spectral models such as CHIANTI. These spectra are used in temperature response and filter ratio methods
Temperature Response#: The expected response of the instrument to isothermal plasma as a function of temperature, given in units of DN cm⁵ s⁻¹ pix⁻¹ for each filter channel. Calculated using CHIANTI atomic models and user-defined abundances.