The Einstein Probe Follow-up X-ray Telescope (EP-FXT) Calibration Database (CALDB) is an essential resource for researchers working with EP-FXT data. The CALDB contains a comprehensive collection of calibration files necessary for accurate data reduction and analysis. These files provide detailed information about the properties and performance of the EP-FXT detectors, mirrors, and other instrument components. The CALDB is organized into a well-defined directory structure, making it easy for users to locate and access the calibration files required for their specific analysis tasks.

Some of the key calibration files included in the EP-FXT CALDB are:

1）Ancillary Response Files (ARF): These files contain information about the effective area of the detectors and mirrors as a function of energy.

2）Response Matrix Files (RMF): These files characterize the energy response of the EP-FXT detectors, accounting for energy dispersion and detector resolution.

3）Point Spread Function (PSF) files: These files describe the spatial distribution of X-ray photons as they are focused by the EP-FXT mirrors.

4）Energy Encircled Fraction (EEF) files: These files provide information on the fraction of energy contained within a given radius for a point source.

5）Telescope Definition (TELDEF) files: These files describe the geometry and alignment of the EP-FXT detectors and mirrors.

6）Vignetting files: These files contain information on the reduction of the telescope's effective area due to off-axis angles.

7）Filter Transmission (FTRANS) files: These files describe the transmission properties of the filters used in EP-FXT.

8）Quantum Efficiency (QE) files: These files provide information on the detectors' sensitivity to incoming photons as a function of energy.

9）Gain and Charge Transfer Inefficiency (GAIN) files: These files contain information about the gain calibration and charge transfer inefficiency of the EP-FXT detectors.

10）Mirror effective area (EFF) files: These files provide data on the reflectivity and efficiency of the EP-FXT mirrors as a function of energy.

11）Background files: These files contain information on the instrumental and astrophysical background components relevant to the EP-FXT observations.

   The EP-FXT CALDB plays a crucial role in ensuring that researchers can obtain the most accurate and reliable results from their analysis of EP-FXT data. By providing up-to-date calibration information, the CALDB enables scientists to fully exploit the exceptional capabilities of the Einstein Probe Follow-up X-ray Telescope and contribute to the advancement of our knowledge of the high-energy universe.