October 31, 2014

27.04.11: MeerKAT & the Bid for SKA.

Artist’s impression of a SKA offset Gregorian dish. (Credit: Swinburne Astronomy Productions on a Creative Commons 3.0 license).

African radio astronomers are taking an innovative approach to a bid in hosting a unique proposal. The idea is known as the Square Kilometer Array, a radio observatory that will employ hundreds of dishes over a large area to scan and survey the radio sky in unprecedented detail. Much like the Allen Telescope Array being built in California, SKA’s strategy is to use the technique known as radio interferometry and go for many small dishes linked together rather than one large single antenna.

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22.01.11: A Quasar Campaign.

  Field for 3C 273. (Credit: Marcus Hauser Landessternwarte Heidelberg-Koenigstuhl)

   A call recently went out from the American Association of Variable Star Observers (AAVSO) that we thought was worth passing along. Specifically, Alert Notice 430 is calling for well-equipped and skilled observers to monitor to two exotic objects: Blazar-type quasars 3C 273 and 3C 279. If 3C 273 is sounding familiar, that’s because it was one of our astronomy challenges last year; at around magnitude +12.7, 3C 273 was the first quasar identified as such and is one of the brightest quasars in the sky. [Read more...]

10.04.10- Radio Astronomers Refine Celestial Grid.

(Credit: Image courtesy of NRAO/AUI and Earth image courtesy of the SeaWiFS Project NASA/GSFC and ORBIMAGE)

(Credit: Image courtesy of NRAO/AUI and Earth image courtesy of the SeaWiFS Project NASA/GSFC and ORBIMAGE)

 The VLBA family of radio telescopes!

   Getting a good fix on positions both on the Earth and in the sky is tougher than it may sound. Tectonic plates move. The Moon raises tides under our feet. The whole planet orbits our Sun, which is itself flying about the galaxy and getting jostled by other stars, as the galaxies themselves are flying apart. Last year, however, astronomers at the National Science Foundation’s Very Long Baseline Array of radio telescopes tackled the problem in a novel way. Using 35 radio telescopes worldwide, they monitored and measured the positions 243 quasars over a 24 hour period starting November 18th 2008. Quasars are ideal candidates for this kind of measurement because of their extreme distance. These high precession measurements break the old record for the most radio dishes employed, which stood at 23. The telescopes utilized a method known as Very Long Baseline Interferometry, which combines simultaneous signals collected over individually spaced telescopes to increase resolution power. Headquartered in Socorro, New Mexico, the VLA’s data will not only refine astronomical measurements, but increase the accuracy of geophysical science as well.

18.03.10: ALMA in Action.

 

ALMA antenae at sunset. (Credit: ESO/NAOJ/NRAO).

ALMA antennae at sunset. (Credit: ESO/NAOJ/NRAO).

  

    A unique trio of antennae has been successfully installed in the high Chilean desert. ALMA, the Atacama Large Millimeter Array, is a series of 12-meter diameter antennae that will scan the sky between the infrared and radio wavelengths. This area of the spectrum is strongly absorbed by atmospheric water vapor, hence the high and dry locale of 9,500 on the Chanjnantor plateau. Recently, engineers linked the first of three antennae to observe an astronomical source; quasar 1924-292. The link up is crucial to ALMA’s use as an interferometer, and should start producing its first scientific results in 2011. Ultimately, ALMA will be a series of 66 dishes working in unison to probe the cosmos.