Notes:

1. This simulator gives the observational results for one of the two FXT modules.
2. The simulation of FXT is based on the open source package SIXTE ( Dauser, T. et al. A&A, 630, A66(2019)).
3. The particle background, which is ~3.6e-2 counts/s/keV in the whole image area of pnCCD, is derived from a previous Geant4 simulation (the latest value is 3.1e-2 counts/s/keV, J. Zhang, et al. Astroparticle Physics, 137 (2022) 102668).
4. The diffuse X-ray background model is adopted from D. McCammon, et al. (ApJ, 576, 188(2002)).
   For more details, please refer to J. Zhang, et al. (Astroparticle Physics, 137 (2022) 102668).
5. The ancillary file (arf) comes from our simulation. Other calibration files such as the response (rmf), point-spread-function (psf) and vignetting files come from the publicly released CALDB of eRosita , considering that the on-ground calibration of FXT has not finished at the moment, and that the design of FXT is nearly identical to a single telescope module of eRosita.
6. The output files include the image of the entire filed of view, the intrinsic source (background-subtracted) and background spectra and light curves, as well as the response and ancillary files which are required by the spectral analysis.
7. The significance is calculated based on the source and background rates at 0.5-10 keV within a circle with a radius of 1.5 arcmin centered at the foci.
8. If too few source photons (<20) are generated, a warning message will be displayed, and The following analysis will not be performed.