Ted Forte replies: Distance estimates made by different methods often vary greatly for the same object--and, as you've noted, redshift
can be most problematic to interpret.
The zCosmos-deep galactic survey  consists of a collection of visible galaxies with respective redshifts
obtained for a given spectroscopic area in the sky.
In order to be more precise in this assessment we must take into account the fact that the redshifts
of GRB090219 and of GRB091230A were not determined.
Another recent Hubble survey also found a handful of faraway galaxies with redshifts
possibly in the range of 8.5 to 10.
Measuring velocity is based on an effect seen in everyday life: as an object moves further away, its light shifts to longer, or red, wavelengths (called redshift
Quantization and Anomalous Redshifts
Tifft expanded his database to other clusters of galaxies to see if a relationship between redshifts
and magnitudes was present.
A small redshift
of perhaps 15 km/sec is calculated in this measurement.
In the tired-light cosmology where redshifts
are explained by a decay of the photon energy, the following equation replaces the cosmological redshift
equation of the expanding Universe theory:
range from 8.6 (590 million years after the Big Bang) to 9.5 (520 million years).
"If we could measure the redshifts
of millions of quasars, we could use them to map the structures in the universe out to a large redshift
," Starkman noted.
The results obtained with the equation we derived for the propagation of light solved jointly with the Friedmann equation are inconsistent with observations as it is common to observe galaxies with redshifts
up to 6, and more recently beyond 8.5 .
To be able to detect these very distant objects which were forming near the beginning of the universe, astronomers look for sources which have very high redshifts
"By far the most intriguing result of these initial studies was the suggestion that galaxy redshifts
take on preferred or 'quantized' values.
If we did not compute the scale factor on the basis of metric distances, the equation would fail to work with cosmological redshifts
, which are a homothetic transformation for describing the evolution of light wavelength.