This WEB-based X-ray events simulator has been developed at the ASI Space Science Data Center (SSDC) to support Swift users (and team members) in simulating data taken with the Swift X-Ray Telescope (XRT) operated in different instrument modes.
The tool is an evolution of the X-ray events simulator developed for the BeppoSAX mission. Currently it supports the following simulation possibilities:
- Random sky plus a generic pointlike target with a specified spectral shape
- Random sky plus a generic extended target with a specified spectral shape.
- Specific sky areas with fluxes and source positions taken from one of the following ROSAT catalogs :
WGACAT, ROSATSRC, RASS (All Sky Survey).
- Gamma Ray Bursts and X-ray afterglows observed at different times from the main GRB event.
- Fields with position and spectral information provided by the user
The background events are generated using the following models:
- a Thermal Bremsstrahlung spectrum with T=40 keV for the (vignetted) Cosmic Background with an intensity of 2.5e-4 ct/s/sqarcmin and
- a Flat spectrum (independent of energy) for the particle/electronic background, with an intensity of 3.e-5 ct/s/sqarcmin.
The output of a simulation run consists of two level-2 FITS/OGIP event files written in a format that is very similar to that used for real XRT data. One file includes the list of photons as observed in the chosen instrument mode; the second file includes all the photons that would have been detected in the ideal case of Photon Counting mode with zero readout time. Both files can be retrieved by the user for off-line scientific analysis with the official XRT data analysis software or equivalent packages. Alternatively the simulated data can be displayed in various ways and (partly) analyzed on-line using the "On-line analysis" option.