All Threads - CIAO 3.4

Introductory

These threads explain the basics of Sherpa: reading data, establishing models, fitting, and plotting. Information on how to customize plots via the Sherpa state objects (a.k.a. configuration variables) is covered as well.

Fitting

Sherpa provides extensive facilities for modeling and fitting data. The topics here range from basic fits using source spectra and responses to more advanced areas such as simultaneous fits to multiple datasets, accounting for the effects of pileup, and fitting spatial and grating data.

Spectral (1-D) Data
- Introduction to Fitting PHA Spectra
- Changing the grouping scheme of a dataset within Sherpa
  Uses: the sherpa_utils.sl S-Lang script
- Introduction to Fitting ASCII Data with Errors: Single-Component Source Models
- Fitting PHA Data with Multi-Component Source Models
- Independent Background Responses
- Simultaneously Fitting Two Datasets
- Simulating 1-D Data: the Sherpa FAKEIT Command
- Simulating 1-D Data: the S-lang Script simspec
  Uses: the simspec script
- Simulation for Suzaku: Evaluate HXD systematic errors
- Using A Pileup Model
- See also: a comparison, for low pileup fractions, of the pileup models in Sherpa and XSpec with that in ISIS.
Spatial (2-D) Data
- Fitting FITS Image Data
  Uses: the sherpa_plotfns.sl S-Lang script
- Using an Exposure Map in Fitting Image Data
- Using a PSF Image as the Convolution Kernel
- See also: the Obtain and Fit a Radial Profile thread
Grating Data

Plotting

Sherpa allows the user to plot data, fits, statistics, ARFs, contours, surfaces, and more. These threads describe the basics of plotting as well as various methods for customizing plots.

Data Visualization
Changing the look of Sherpa plots using setplot.sl
Uses: the setplot.sl S-Lang script
Step-by-Step guide to changing the look of Sherpa plots
Advanced customization of Sherpa plots
Uses: the sherpa_plotfns.sl S-Lang script

Statistics

Sherpa provides numerous tools for determining goodness of fit, errors in parameter values, confidence intervals, and other statistical measures of a model's validity. These threads describe how to use these tools in your analysis.

Estimating Errors and Confidence Levels
Uses: the paramest.sl S-Lang script
Step-by-Step Guide to Estimating Errors and Confidence Levels
Accessing fit results using S-Lang
Visit the The California-Harvard Astrostatistics Collaboration page

S-Lang

The S-Lang language and Sherpa/S-Lang module provide a powerful means of extending Sherpa's capabilities through custom-made functions and scripts. The threads here introduce Sherpa's S-Lang functionality and provide some examples of its use.

Introduction to the Sherpa S-Lang Module
Changing the grouping scheme of a dataset within Sherpa
Uses: the sherpa_utils.sl S-Lang script
Fitting FITS Image Data
Uses: the sherpa_plotfns.sl S-Lang script
Accessing fit results using S-Lang
Advanced customization of Sherpa plots
Uses: the sherpa_plotfns.sl S-Lang script
Calculating K-corrections using S-Lang and Sherpa
Uses: the sherpa_utils.sl S-Lang script
See the Preparing to Run ChaRT thread for another example of using S-Lang to extend Sherpa

Miscellaneous

These threads describe other tasks that one can perform using Sherpa.

Simulating 1-D Data: the Sherpa FAKEIT Command
Simulating 1-D Data: the S-lang Script simspec
Uses: the simspec script
Simulation for Suzaku: Evaluate HXD systematic errors

Sherpa Threads for CIAO 3.4

Introductory

Fitting

Spectral (1-D) Data

Spatial (2-D) Data

Grating Data

Plotting

Statistics

S-Lang

Miscellaneous