|SKA Telescope- How powerful are they?|
This article is extracted from the official SKA baseline design document SKA-TEL-SKO-DD-001 revision 1 dated 2013-03-12. The purpose here was to outline how powerful the SKA telescopes are without involving deep technical terms. For full, accurate and updated information, please visit www.skatelescope.org. The driving concepts for the SKA have been to develop high sensitivity as well as high “survey-speed” telescopes.
o The SKA Organisation has selected 2 sites for the SKA- one in Western Australia and one in Southern Africa. The telescope facilities for SKA1 have been defined as SKA1-low (a low-frequency aperture array); SKA1-survey (a mid-frequency array of dishes equipped with Phased-Array Feeds), both arrays to be built in Australia; and SKA1-mid (a mid-frequency array of parabolic dishes) to be built in South Africa. SKA1 has been scheduled for operation in 2019 and the 2nd phase called SKA2 has been scheduled for operation in 2024.
The receptors will consist of an array of ~250,000 log-periodic dual-polarised antenna elements. The antenna array will operate from 50 MHz to ~350 MHz (covering a similar frequency to LOFAR telescope and MWA telescope). Its sensitivity will be ~1000 m2 / K at frequencies above 110 MHz at the zenith- an increase of more than an order of magnitude albeit being optimised for brightness temperature sensitivity. The elements will be grouped into 866 35m diameter stations and beam-formed to expose a field-of-view of ~20 deg2 in a single smooth beam.
The telescope receptors will consist of 64 13.5m diameter dishes from the MeerKAT array and 190 15m SKA1 dishes. Three spiral arms will extend to a radius of ~100 km from the centre. SKA1-mid will cover the continuous frequency range from 350 MHz to at least 3050 MHz in three receiver bands. At the frequency of 1.4 GHz, SKA1-mid provides an order of magnitude better than existing instruments in terms of resolution, sensitivity and survey speed.
The telescope receptors will consist of 36 12m diameter dishes from the ASKAP array and 60 15m SKA1 dishes. Three spiral arms will extend to a radius of ~25 km from the centre, although space is available for ~50-km arms, if needed. SKA1-survey will cover the continuous frequency range from 650 MHz to 1670 MHz in a single dual-polarised PAF in a 500 MHz wide instantaneous bandwidth. The PAF provide a constant Field-of-View of approximately 18 deg2 in 36 beams at the highest frequency. It is comparable with the JVLA telescope in SEFD (System Equivalence Flux Density), but the SKA1-survey PAF-enabled field-of-view, about 100 times larger, provides a huge increase in survey speed.
o Note: LOGAR, MWA, JVLA are operating telescopes as in May 2013 and are quoted here for reference.