Output Data Formats#

simtools workflows exchange structured data products between preparation, production, and validation steps. This page summarizes the main formats and their typical roles.

Event-level simulation output#

  • EventIO / sim_telarray output (.simtel, often compressed): telescope-level simulated events and embedded metadata.

  • EventIO output is consumed by downstream CTAO tools and by simtools validation utilities.

Tabular workflow products#

  • ECSV (.ecsv): human-readable tables with units and metadata, used for production grids, CORSIKA limits, and statistics summaries.

  • HDF5 (.hdf5): compact multidimensional data products used for histogram-based workflows and intermediate analysis results.

Trigger histograms#

Trigger-histogram products store dense arrays below TRIGGER_HISTOGRAM_DENSE/<reference_id>/<name>. Each histogram group contains a values dataset and one edges_<axis> dataset for every axis. The axis_names and axis_units attributes are JSON arrays with one entry per axis, or JSON null when metadata is absent; individual units may also be null. The parent TRIGGER_HISTOGRAM_DENSE group has a format_version attribute set to 2.

Configuration and parameter files#

  • YAML (.yml, .yaml): workflow configuration and schema documents.

  • JSON (.json): model-parameter records and machine-oriented interchange products.

Selection guidance#

  • Use ECSV when tables need inspection, version control, or manual review.

  • Use HDF5 for large numeric arrays and histogram products.

  • Use YAML and JSON for configuration and schema-validated parameter definitions.

For metadata structures attached to these formats, see Metadata.