# 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.

### Cosmology Calculator I

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.

### Cosmology Calculator II

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.

### Cosmology Calculator III

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).

### Cosmology Calculator IV: CosmoTools

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.