pycf3 - Cosmicflows Galaxy Distance-Velocity Calculator client for Python

QuatroPe Travis-CI License Python 3.7+ PyPI


pycf3 is a Python client for the Cosmicflows-3 Distance-Velocity Calculator, and NAM Distance-Velocity Calculator

Code Repository & Issues


pycf3 is under The BSD 3 License

The BSD 3-clause license allows you almost unlimited freedom with the software so long as you include the BSD copyright and license notice in it (found in Fulltext).

Basic Install


$ pip install pycf3

Development Install

Clone this repo and install with pip

$ git clone
$ cd pycf3
$ pip install -e .

Quick Usage

>>> import pycf3
>>> cf3 = pycf3.CF3()
>>> result = cf3.calculate_distance(velocity=9000, glon=283, glat=75)
>>> print(result.observed_velocity_)
>>> result.observed_distance_

For more information, read the tutorial in the documentation.


  • If you use the results of this work in your research or other applications, please cite Kourkchi et al. 2020, AJ, 159, 67
  • Please acknowledge pycf3 in any research report or publication that requires citation of any author’s work. Our suggested acknowledgment is:
The authors acknowledge the pycf3 project that contributed to the research reported here. <;


All data exposed by pycf3 belongs to the project

Cosmicflows-3 Distance-Velocity Calculator ( Copyright (C) Cosmicflows Team - The Extragalactic Distance Database (EDD)

Please cite:

Kourkchi, E., Courtois, H. M., Graziani, R., Hoffman, Y., Pomarede, D., Shaya, E. J., & Tully, R. B. (2020). Cosmicflows-3: Two Distance–Velocity Calculators. The Astronomical Journal, 159(2), 67.


    author = {{Kourkchi}, Ehsan and {Courtois}, H{\'e}l{\`e}ne M. and
        {Graziani}, Romain and {Hoffman}, Yehuda and {Pomar{\`e}de}, Daniel and
        {Shaya}, Edward J. and {Tully}, R. Brent},
    title = "{Cosmicflows-3: Two Distance-Velocity Calculators}",
    journal = {\aj},
    keywords = {590, 1146, 902, 1968, Astrophysics - Cosmology and
        Nongalactic Astrophysics, Astrophysics - Astrophysics of Galaxies,
        Astrophysics - Instrumentation and Methods for Astrophysics},
    year = 2020,
    month = feb,
    volume = {159},
    number = {2},
    eid = {67},
    pages = {67},
    doi = {10.3847/1538-3881/ab620e},
    archivePrefix = {arXiv},
    eprint = {1912.07214},
    primaryClass = {astro-ph.CO},
    adsurl = {},
    adsnote = {Provided by the SAO/NASA Astrophysics Data System}



This project is part of the QuatroPe scientific tools.

Indices and tables