Ground Instrumentation

PAU – Physics of the Accelerating Universe


The PAU Camera (PAUCam) consists of an array of 18 red-sensitive CCD’s of 4kx2k pixels. The Camera is equipped with a system of 40 narrow-band (10nm width) and 6 wide-band (100nm width) filters spanning the entire optical range (300nm to 1000nm). This results in a multicolor map of the sky where each pixel has a low resolution spectra.

PAUCam will image about 2 square degree per night, providing photometric spectra for around 30,000 galaxies, 5,000 stars and 1,000 quasars.


Several observations indicate an apparent acceleration of the expansion rate of the Universe (Nobel Prize 2011), namely that the universe seems to be expanding faster now than in the past.

The main objective of the PAU project is to understand the Physics of the Accelerating Universe (PAU) by means of a large cosmological galaxy survey that map the cosmological expansion with unprecedented combination of density and radial distance accuracy. The PAU Survey will provide simultaneous measurement of the cosmic expansion and growth history of structures to differentiate between the hypothetical existence of dark energy and alternative explanations, such as the modification of gravity or other laws of nature.


PAUCam has been designed to be mounted on the prime focus of the William Herschel Telescope (WHT), a 4m-class telescope located in the Observatorio del Roque de los Muchachos in La Palma, Canary Islands. PAUCam is expected to be installed and running at the WHT in 2013.

IEEC’s Contribution

The PAUCam consortium is comprised by IEEC, IFAE/PIC and CIEMAT. IEEC has the leading role (Principal Investigator) for the PAU Camera and the PAU Survey Science.

In addition, IEEC is responsible for the Data Management and Data Reduction in collaboration with the other PAU institutions. The institute also produces the MICE numerical simulations obtained with the Marenostrum Barcelona Supercomputer Center, required for its design and exploitation.