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Please Note: An updated, and maintained, version of this content is available on the Maximum Likelihood page.

Fermitools Cicerone—Likelihood

This section explains why a maximum likelihood technique is usually necessary to analyze the LAT data, describes the methodology behind the maximum likelihood tools, and provides guidance into the use of these tools.

• The Data Analysis Challenge
• Likelihood Overview
• The Functional Form of the Likelihood
• XSPEC Analysis of Fermi Data
• Choosing the Data to Analyze—Regions of Interest and Source Regions
• Model Selection
• Calculating Livetime and Exposure
• Likelihood Model Fitting
• Source Detection and Localization
• Time-Series Analysis with Likelihood

» Forward to the data analysis challenge section
» Back to the beginning of the Cicerone

• Curator: J.D. Myers
• NASA Official: Elizabeth Hays
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• › Page Last Updated: Tue, Aug 05, 2025