Precision Array for Probing the Epoch of Reionization

Precision Array for Probing the Epoch of Reionization

Alternative names	PAPER
Location(s)	Meerkat National Park, Karoo Hoogland Local Municipality, Namakwa District Municipality, Northern Cape, RSA
Coordinates	30°43′21″S 21°25′40″E / 30.7224°S 21.4278°E / -30.7224; 21.4278
Wavelength	1.5 m (200 MHz)–3.0 m (100 MHz)
First light	October 2009
Telescope style	radio interferometer
Number of telescopes	64
Collecting area	18,000 m2 (190,000 sq ft)
Website	eor.berkeley.edu
Location of Precision Array for Probing the Epoch of Reionization
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The Donald C. Backer Precision Array for Probing the Epoch of Reionization (PAPER) is a radio interferometer funded by the National Science Foundation^[1] to detect 21 cm hydrogen (HI) fluctuations occurring when the first galaxies ionized intergalactic gas at around 500 million years after the Big Bang. PAPER is a focused experiment aimed toward making the first statistical detection of the 21 cm reionization signal. Given the stringent dynamic range requirements for detecting reionization in the face of foregrounds that are five orders of magnitude brighter, the PAPER project is taking a carefully staged engineering approach, optimizing each component in the array to mitigate, at the outset, any potentially debilitating problems in subsequent data calibration and analysis. This staged approach addresses the observational challenges that arise from very-wide-field, high-dynamic-range imaging over wide bandwidths in the presence of transient terrestrial interference. PAPER began as a collaboration between Don Backer of the UC Berkeley Radio Astronomy Laboratory and Richard Bradley of the National Radio Astronomy Observatory. With Backer's passing in 2010, Aaron Parsons has assumed leadership of PAPER on the side of UC Berkeley.

The two fundamental concerns that most influence the design of any HI reionization detection instrument are removing foregrounds and achieving the requisite sensitivity. The PAPER approach heavily emphasizes the former; the level of instrumental calibration and foreground characterization that will be required to model and remove polarized galactic synchrotron emission, continuum point-sources, and galactic/extra-galactic free-free emission is unprecedented in the 100–200 MHz band expected to encompass reionization.

PAPER consists of two distinct arrays: one located at the NRAO site in Green Bank, WV, which is used primarily for engineering investigations and field testing, and another located at the South African SKA site in the Meerkat National Park located in the Karoo desert of the Northern Cape, South Africa,^[2] which is used for science observations.