Reconstruction (reco)

Introduction

ctapipe.reco contains functions and classes to reconstruct physical shower parameters, using either stereo (multiple images of a shower) or mono (single telescope) information.

All shower reconstruction algorithms should be subclasses of Reconstructor which defines some common functionality.

Currently Implemented Algorithms

Moment-Based Stereo Reconstruction

Moment-base reconstruction uses the moments of each shower image (the Hillas Parameters to estimate the shower axis for each camera, and combines them geometrically to estimate the true shower direction.

The implementation is in the HillasReconstructor class.

Template-Based Stereo Reconstruction

Moment-base reconstruction uses the a fit of the full camera images to an expected image model to find the best fit shower axis, energy and depth of maximum. The implementation is in the ImPACTReconstructor class.

• Analysis with ImPACT
  • What is ImPACT?
    • Image Templates
    • Image Prediction
    • Calculating Image Likelihood
    • Maximum Likelihood Fitting
    • Performance
  • Running an ImPACT analysis
    • Choosing you minimiser

Reference/API

ctapipe.reco Package

Classes

Reconstructor(**kwargs)	This is the base class from which all direction reconstruction algorithms should inherit from
ShowerProcessor(**kwargs)	Needs DL1_PARAMETERS as input.
HillasReconstructor(**kwargs)	class that reconstructs the direction of an atmospheric shower using a simple hillas parametrisation of the camera images it provides a direction estimate in two steps and an estimate for the shower’s impact position on the ground.
ImPACTReconstructor(**kwargs)	This class is an implementation if the impact_reco Monte Carlo Template based image fitting method from parsons14.
HillasIntersection(**kwargs)	This class is a simple re-implementation of Hillas parameter based event reconstruction.

ctapipe.reco.hillas_intersection Module

TODO: - Speed tests, need to be certain the looping on all telescopes is not killing performance - Introduce new weighting schemes - Make intersect_lines code more readable

Classes

HillasIntersection(**kwargs)

This class is a simple re-implementation of Hillas parameter based event reconstruction.

ctapipe.reco.hillas_reconstructor Module

Line-intersection-based fitting for reconstruction of direction and core position of a shower.

Classes

HillasPlane(p1, p2, telescope_position[, weight])	a tiny helper class to collect some parameters for each great great circle
HillasReconstructor(**kwargs)	class that reconstructs the direction of an atmospheric shower using a simple hillas parametrisation of the camera images it provides a direction estimate in two steps and an estimate for the shower’s impact position on the ground.

ctapipe.reco.impact Module

Functions

energy_prior(energy[, index])
xmax_prior(energy, xmax[, width])
guess_shower_depth(energy)	Simple estimation of depth of shower max based on the expected gamma-ray elongation rate.

Classes

ImPACTReconstructor(**kwargs)

This class is an implementation if the impact_reco Monte Carlo Template based image fitting method from parsons14.

ctapipe.reco.reco_algorithms Module

Classes

Reconstructor(**kwargs)	This is the base class from which all direction reconstruction algorithms should inherit from
TooFewTelescopesException
InvalidWidthException