Pierre Auger Observatory - cloud monitoring system upgrade

Scheduled for commissioning 2012

The Pierre Auger Observatory is devoted to the study of ultra-high energy cosmic rays. The Observatory operates from near the city of Malargüe in Mendoza province, Argentina. It has a current proposal for a larger complementary site in south east Colorado, USA. The Observatory is a scientific collaboration between 18 countries around the world and the University of Adelaide is currently the only Australian university with scientists in the collaboration.

The Observatory operates with 1600 water Cherenkov detectors. The water tanks are fitted with photo multiplier tubes that detect Cherenkov light allowing the determination of the number of particles in each cosmic ray shower. Four sites, each containing six UV telescopes, view nitrogen fluorescence light from incoming cosmic ray showers over the 3000 km² area of the Observatory. Each of those sites comprise six 4-metre diameter Schmidt telescopes, each with approximately 500 photomultiplier tubes and an elevation range of 2-30^o.

Australia, through the University of Adelaide, has played a central role in the Observatory from the beginning (the Observatory began taking data in 2004), based on its long experience in high energy astrophysics and, particularly, in the atmospheric fluorescence techniques employed by the optical detectors of the Observatory.

Atmospheric monitoring

The University of Adelaide's contribution to the Observatory workload is largely through leading data analysis work, observing shifts, and, importantly, atmospheric monitoring, a critical service task for the Observatory. Atmospheric monitoring is important since the fluorescence detectors often view cosmic ray air showers at distances of over 30 km and corrections must be made for cloud obscuration and the absorption and scattering of the light by molecules and aerosols. Thus the presence of night-time cloud must be monitored over the full Observatory area.

Using EIF funding the University of Adelaide will build four new cloud monitoring systems for the Observatory. Each of the four new cloud cameras will scan across the field of view of each fluorescence detector telescope, plus surrounding areas of sky, using a commercial pan-and-tilt platform as used in security camera applications. The images thus produced will provide both data on cloud cover for each fluorescence telescope pixel and real-time all-sky cloud images for observers.

The new cloud detectors are expected to be commissioned in late 2012.

Key Contacts

Prof Roger Clay and Prof Bruce Dawson, University of Adelaide.