Description
The 2dF survey covered an area of about 1500 square degrees, surveying regions in both the north and the south galactic poles. The name derives from the fact that the survey instrument covers an area of approximately two square degrees.
The areas selected for observation were previously surveyed by the massive APM Galaxy Survey (on which Steve Maddox also worked). The regions surveyed cover roughly 75 degrees of right ascension for both bands, and the declination of the North Polar band was about 7.5 degrees while the declination of the South Polar band was about 15 degrees. Hundreds of isolated two degree fields near the South Polar band were also surveyed (see this illustration, where black circles represent survey fields, and the red grid represents the earlier APM survey).
In total, the photometry of 382,323 objects were measured, which includes spectra for 245,591 objects, of which 232,155 were galaxies (221,414 with good quality spectra), 12,311 are stars, and 125 are quasi-stellar objects (quasars). The survey necessitated 272 required nights of observation, spread over 5 years.
The survey was carried out with the 4 metre Anglo-Australian Telescope, with the 2dF instrument installed at the primary focus permitting the observation of a field of 2 degrees per pointing. The instrument possesses a spectrograph equipped with two banks each of 200 optical fibres, permitting the simultaneous measurement of 400 spectra.
The limiting apparent magnitude of the survey is 19.5, covering objects with a redshift mostly within less than z=0.3 and a median redshift of 0.11. The volume of the Universe covered by the survey is approximately 108 h−1 Mpc3, where h corresponds to the value of the Hubble constant, H0, divided by 100. H0 is approximately 70 km/s/Mpc. The largest redshift observed by the survey corresponds to a distance of 600 h−1 Mpc.
Read more about this topic: 2dF Galaxy Redshift Survey
Famous quotes containing the word description:
“God damnit, why must all those journalists be such sticklers for detail? Why, they’d hold you to an accurate description of the first time you ever made love, expecting you to remember the color of the room and the shape of the windows.”
—Lyndon Baines Johnson (1908–1973)
“The next Augustan age will dawn on the other side of the Atlantic. There will, perhaps, be a Thucydides at Boston, a Xenophon at New York, and, in time, a Virgil at Mexico, and a Newton at Peru. At last, some curious traveller from Lima will visit England and give a description of the ruins of St Paul’s, like the editions of Balbec and Palmyra.”
—Horace Walpole (1717–1797)
“It is possible—indeed possible even according to the old conception of logic—to give in advance a description of all ‘true’ logical propositions. Hence there can never be surprises in logic.”
—Ludwig Wittgenstein (1889–1951)