The RHESSI telemetry data are not pre-binned in any way; they include all of the information about each detected photon.  This leaves the data analyst free to select the time resolution and spectral  range and resolution that are optimum for the event under study and scientific objectives.

Analysts use the RHESSI spectrum object software to accumulate the count-rate data binned into any time and energy binning desired, for selected detectors, and with other options such as decimation and pileup correction.  The user can view the accumulation in either dimension as a time history for multiple energies, or a spectrum for multiple times and extract the data for further analysis.  For further analysis using OSPEX (see below), the user instructs the RHESSI spectrum object to write two FITS files for the spectrum data and the corresponding detector response matrix (DRM).

To convert the count-rate spectrum to the incident photon spectrum, the spectrum and DRM FITS files created by the RHESSI spectrum object are input to the spectral analysis package, OSPEX. OSPEX facilitates subtracting background and fitting the count-rate data to combinations of approximately 30 spectral forms such as thermal and power law to produce a parameterized model of the photon spectrum.