# COSMOLOGY CALCULATORS

NED is providing these links to outside sites at the specific request
of users and as an additional service to extragalactic researchers in
general. The NED Team has not fully validated any of these
calculators, and questions concerning the algorithms used, their range
of application and the precision of the returned results should be
directed to the original Web site creators.

Ned Wright, UCLA

This calculator allows one to input user-selected values of the Hubble
constant, Omega(matter), Omega(vacuum) and the redshift z, and returns
the current age of the Universe, the age, the co-moving radial distance
(and volume) and the angular-size distance at the specified redshift,
as well as the scale (kpc/arcsec) and the luminosity distance.

Curator's email address:
wright@astro.ucla.edu

Nick Gnedin, University of Colorado

This calculator accepts Omega(total), a value of the Hubble constant,
plus either a redshift or a scale factor, and it computes: (1) the age
and lookback time, (2) the past and future horizon distances, (3) the
angular size for a given physical size (and vice versa), (4) the
angular distance, (5) the Hubble parameter at the given redshift, and
(5) the distance between two input redshifts. Physical scale units can
be in either parsecs or lightyears.

Curator's email address:
gnedin@casa.colorado.edu

Chip Kobulnicky, University of Wyoming

This calculator allows one to input a redshift (or a list of up to 20
redshifts), the Hubble constant, Omega(matter), Omega(Lambda) and a
luminosity, returning the age of the Universe at redshift z, the
look-back time to redshift z, the angular scale, the surface
brightness factor, the observed flux, the effective distance modulus and
the K-correction (band-pass term only).

Curator's email address:
chipk@uwyo.edu

Alberto Cappi, Bologna

This simple program calculates luminosity and
co-moving distances from a user-specified redshift, deceleration
parameter and Hubble constant. Presently the calculator uses only
the standard Friedmann-Lemaitre (i.e., Lambda = 0) cosmological models.

Curator's email address:
cappi@@bo.astro.it

### K-Correction Calculators

#### Ultraviolet to Near-Infrared K-corrections
calculator

This service provides analytical approximations of
K-corrections applicable to quiescent ("red and dead"), star-forming, and
starburst galaxies (non-AGNs) with z < 0.5. The photometric bands covered
include GALEX FUV/NUV, SDSS ugriz, Johnson/Cousins UBVRI, UKIRT YJHK, and 2MASS
JHKs.

See Chilingarian &
Zolotukhin 2012, MNRAS, 419, 1727.

The *calc_kcorr* function
in the Sherpa data analysis package can be used to calculate K-corrections
for various spectral models at X-ray energies.