Pierre Auger Observatory


The Pierre Auger Project developed from a suggestion by Jim Cronin and Alan Watson in 1992 to build a giant air shower array with much greater collecting power than had ever been considered previously. The idea developed through a sequence of workshops in Paris (1992), Adelaide (1993), Tokyo (1993), and finally at Fermilab in 1995. Jim Cronin was given the title Spokesperson Emeritus in 2002; Alan Watson also became Spokesperson Emeritus in 2007.



Jim W. Cronin and Alan A. Watson suggest building a giant air shower array with much greater collecting power than had ever been considered previously.

Jan. 30 – Jul. 31

Production of a design report – reference design and cost estimate – by the Design Group for the Auger Project hosted by Fermilab, Illinois, USA. This becomes the basis for funding proposals in 17 participating countries.

1995 – Nov.

A meeting is held in Paris to form the collaboration. It chooses site the site of Mendoza, Argentina in the Southern Hemisphere. The Observatory is named after the French physicist Pierre Victor Auger.

1999 – Mar.

Signature of the International Agreement in Mendoza.


Beginning of the construction of the observatory.


The Engineering Array – a full-scale prototype of the first 32 SD stations and a single fluorescence telescope – is operated for 6 months. It is later integrated into the main setup and used for more detailed design choices and calibration.


The Observatory becomes the largest detector in the world for the detection of ultra-high energy cosmic rays.


First physics results are reported from more than 100 surface detector stations.

2007 – May

Release of 1% of the data to the public for outreach purposes. The data can be explored at the website of the Public Event Display (www.auger.org/event-display).

2007 – Nov.

Preliminary results indicate that the directions of origin of the 27 highest-energy events are correlated with the locations of active galactic nuclei (AGNs).


Observation of the energy spectrum of cosmic rays confirmes that the flux is strongly suppressed above 4.1019 eV as predicted by the GZK theory.


Best present limits are set on the detection of photons with an energy of 1018 eV.


Observations of the depth of the maximum of air-shower profiles above 1018 eV give first hints on the composition of cosmic rays at ultra-high energy.


Solar physics with the Auger Observatory.


Measurement of the proton-proton cross section at a centre-of-mass energy of 57 TeV, complementing results from the LHC always below 14 TeV.


Best present limits on the detection of neutrinos with an energy of 1018 eV.


Observation of large-scale anisotropies: Arrival directions of cosmic rays are not evenly distributed, giving hints on the origin whether galactic or extragalactic of cosmic rays at ultra-high energy.


Observations of a deficit in the number of muons in air showers challenge predictions from hadronic interaction models.

2015 – Nov. AugerPrime Celebrate 15 years of achievements and signature ceremony of a new International Agreement for the next ten years (www.auger.org/augerprime).