The First G-APD Cherenkov Telescope

Short Intro

The First G-APD Cherenkov Telescope is the first Imaging Atmospheric Cherenkov Telescope using Geiger-mode avalanche photodiods as photo sensors.

FACT persues two main goals, on the on hand it serves as technology demonstrator for the SiPM technology in gamma-ray astronomy, on the other hand, it continuously monitors the brightest extra-galactic sources of TeV gamma rays.


For a general description of the FACT telescope, have a look into our Design and Operation Paper.

For the analysis of our SiPM performance, see the SiPM Performance Paper.

You can find all of our publications on the Publications Page.

Open Data

From the start on, FACT has made the analysis results of the on-site Quick-Look-Analysis available to the public.

Since November 2017, FACT has gone one step further and has released a datasample of 17.7 hours of high quality Crab Nebula observations along with extensive simulations to the public.

This datasample is available from the telescope raw data upwards on our Open Data Page.

Open Source Software

The FACT Collaboration believes strongly in the importance of Open Source Software to achieve reproducible science results.

You can find most of our software, including our main analysis frameworks FACT-Tools and Mars either in our GitHub organisation or our SVN.