Setup and usage tips is easy to use on Linux and Windows. Windows uses Windows Subsytem for Linux for


After install, if you need the star index files, use:

Linux / Windows Subsystem for Linux

  1. Download/install the pre-compiled binary code

    apt install
  2. Install the star map data necessary to solve images.

    apt install astrometry-data-2mass-08-19 astrometry-data-tycho2-10-19


Using Homebrew:

brew install astrometry-net


The major steps in achieving a useful WCS starfield polynomial fit are:

  1. source extraction (identifying star position in image frame)

  2. quad asterism hashing, including tolerance for star position wiggling due to noise.

  3. Match hash to star catalog, at least 3 choices are available:

  4. Bayesian decision process, find extremely high probability solution or reject.

We have written a separate article on tips and techniques


[Optional] compile

This is normally not necessary, unless you want to customize/optimize.


apt install libcairo2-dev libnetpbm10-dev netpbm libpng12-dev libjpeg-dev zlib1g-dev swig libcfitsio-dev

Install: If you have Anaconda/Miniconda Python as your default, will use them (or whatever your default Python is). Back to at least 0.70, is Python 3 compatible.

curl -O

tar xf*.gz


make py
make extra

make install INSTALL_DIR=~/

Add to ~/.bashrc

export PATH="$PATH:$HOME/"

do not use ~ or you’ll get error

cannot find executable astrometry-engine

Uncomment inparallel in ~/ (or /etc/astrometry.cfg)

Copy the star index files with


If it can’t find the index file, be sure ~/ contains:

add_path /home/username/astrometry/data

~ or $HOME will NOT work!

Reference paper

Program giving azimuth/elevation for each pixel of your sky image

Alternative: online image scaling