Spectral Analysis

**The x-ray spectral analysis consists of a comparison between the
observed pulse height spectrum and a pulse height spectrum calculated
using a given spectral model. The
model, chosen by the user, is convolved with
the instrument and telescope responses.
**

**To obtain the spectral parameters for an x-ray source, several
steps need to be followed. For each source:
**

- extract counts (pulse height spectrum) from the source or region of interest
- select background region and extract counts
- obtain the distribution of the
gain values - for
*Einstein*IPC only - obtain the best fit parameters for a spectral model - repeated for each model of interest
- obtain a 1-D or 2-D grid of values around the best fit values - this can be done for as many models as desired
- determine the flux and luminosity of the source from the best fit model

**Plots of the gain distribution, the pulse height distribution,
the data compared to the
model spectra, and of the **** grids can be generated.
**

- Summary of Tasks in this Section
- A Quick Look at Spectral Fitting
- Notes on IPC and PSPC Spectral Fitting
- Model Spectra for Spectral-Fitting Program
- Structure of the Spectral Package
- *qpspec* - Extraction of Photon Distributions from QPOE files
- *fit* - Fit Data to a Specified Model
- *counts_plot* - Inspection of Results
- *search_grid* - Grid of - default mode
- *grid_plot* - Plot Results on Screen
- *xflux, hxflux* - Calculation of X-ray Flux
- *upspecrdf, downspecrdf* - Transform between RDF and pre-RDF spectral tables
- *xspec* - External Fitting Program
- *qpspec* - Time Resolved Spectral Fitting

1998-06-10