Alternatives¶

IACTrace is not the only tool for simulating segmented telescope optics. This page compares it to other commonly used approaches in the IACT community and beyond.

sim_telarray¶

sim_telarray is the de facto standard for IACT simulations within the Cherenkov Telescope Array Observatory (CTAO) and H.E.S.S. collaborations.

Advantages of sim_telarray:

Mature, validated against real telescope data
Integrated with CORSIKA for full air shower simulation
Handles detector electronics and trigger logic
Well-documented with established analysis pipelines

When to use IACTrace instead:

You need gradients for optimization or inverse problems
You want a Python-native workflow!
You want GPU acceleration
You want standalone optical simulations

Zemax / Commercial¶

Commercial optical design softwares provide comprehensive tools for lens and mirror system design. Zemax is commonly used in the design of telescopes.

Advantages of commercial software:

Full-featured GUI for interactive design
Extensive optimization algorithms built-in
Handles complex optical systems (lenses, coatings, tolerancing)

When to use IACTrace instead:

You don’t want to pay money (duh)
You want to integrate optical simulation with machine learning in jax
You specifically need IACT features (hexagonal sensors, segmented primaries)
You want to use open-source code where you can contribute features

ROBAST¶

ROBAST (ROOT-based simulator for ray tracing) is an open-source non-sequential ray-tracing library built on the ROOT framework, widely used within the CTA collaboration.

Advantages of ROBAST:

Established in the CTA community
Handles complex segmented mirrors and aspherical lenses
Integrates with ROOT analysis ecosystem
Supports Winston cone / light concentrator simulations

When to use IACTrace instead:

You need differentiable simulations for optimization
You want GPU acceleration
You prefer a pure Python workflow without ROOT dependencies

Summary Table¶

Feature	IACTrace	sim_telarray	Commercial	ROBAST
Non-sequential ray tracing	No	No	Yes	Yes
Complex 3D models	No	No	Yes	Yes
Differentiable	Yes	No	Limited	No
Python-native	Yes	No	No	No
GPU support	Yes	No	Varies	No
Open source	Yes	Partial	No	Yes
Cost	Free	Free		Free