In order to enable the correction of photon fluxes a file is produced containing the deadtimes per specified period (minimum 1 second). The calculation is performed by program 'whkproc' from the Science Housekeeping data. The MAIN trigger ratemeter counts the number of events which triggers the low level discriminator of the Main A nnode section of detector. The LOGIC trigger ratemeter counts the number of events which pass the first validation check in the Digital Frontend and triggers the Event Processor to transfer the event data into the Event Processor. During the transfer process the ratemeter is stopped and also if for any reason buffers temporarily cannot be sent to the telemetry. This allows the calculation of the dead-time of the instrumant. Both meters are reset to zero every second. Therefore the deadtime = ( RATE_MAIN - RATE_LOGIC ) / RATE_MAIN and the actual_flux = measured_flux / ( 1 - deadtime ) The deadtime is stored in a FITS file together with the time in Modified Julian Day plus the accumulation or binning time in seconds