Data package for Skyfield
Data files for Skyfield
Skyfield is a Python library for astronomical computations. It depends on various data files to accurately compute moon phases, planet positions, etc.
Several issues are raised by these data files:
- If they're not found in the path of the
Loader, they're downloaded at runtime. Depending on the archive you're requesting, some files might be very large, causing a long delay (directly related to your network bandwidth). In the case of a web server app, you'd cause a timeout on client's end.
- They come mainly from 2 sources: NASA's JPL, and the IERS. If one of them is temporarily unavailable, you couldn't perform any computation.
- In some countries, or behind some filtering proxies, some hosts may be blocked.
- These files have an expiration date (in a more or less distant future). As a consequence, even if the files are already downloaded in the right path, at each runtime you could possibly have to download one or more files before making any computation using them.
Currently known expiration dates
Deprecation warning: As of
deltat.preds files are not used anymore. They were not maintained anymore, and Brandon Rhodes switched to other source files for ∆T computations.
Goal for this project
- Providing at least the most common of these assets in Python Package.
- Make regular releases to refresh the files before they expire.
- Provide a warning / logging mechanism when the files are about to expire (or when they are outdated) to still allow you to compute things with the loaded assets, but being informed you need to upgrade.
This way, you could install or upgrade this data package via
Once all the files are on your disk space, you can instantiate your
skyfield loader pointing at their path, without having to worry about anything.
Install the packages using:
pip install skyfield skyfield-data
To create a custom Skyfield loader, use the following code:
from skyfield_data import get_skyfield_data_path from skyfield.api import Loader load = Loader(get_skyfield_data_path()) planets = load('de421.bsp') # this command won't download this file ts = load.timescale(builtin=False) # this command won't download the IERS file
For the record, using
buitin=True as an argument to load the timescale data won't trigger the download of the file, because python-skyfield embeds its own data files as a built-in data source.
If you want to make sure that the data files would never be downloaded, you can also use the
expire option like this:
load = Loader(get_skyfield_data_path(), expire=False)
Whenever a file contained in the catalog has expired, you're going to receive a warning when loading the
>>> from skyfield_data import get_skyfield_data_path >>> from skyfield.api import Loader >>> load = Loader(get_skyfield_data_path()) /home/[redacted]/skyfield_data/expirations.py:25: RuntimeWarning: The file de421.bsp has expired. Please upgrade your version of `skyfield-data` or expect computation errors RuntimeWarning
By default, the loading isn't blocked, but it's strongly recommended to upgrade to a more recent version, to make sure you're not going to make wrong astronomical computations.
By default, the
RuntimeWarning is raised when the file has expired. You may want to be aware of this warning in advance, that is to say a few days or weeks before, in order to eventually upgrade your version of
In order to trigger this warning, you can use the
expiration_limit argument, like this:
>>> from skyfield_data import get_skyfield_data_path >>> from skyfield.api import Loader >>> load = Loader(get_skyfield_data_path(expiration_limit=30)) /home/[redacted]/skyfield_data/expirations.py:25: RuntimeWarning: The file de421.bsp would expire in less than 30 days. Please upgrade your version of `skyfield-data` or expect computation errors RuntimeWarning
expiration_limit argument should be a positive integer (or zero).
We assume that you'll be using a Python3.6+ version for all regular operations.
We're providing a
Makefile with basic targets to play around with the toolkit. use
make help to get more details.
In order to be able to run the
download.py script, we recommend to run it from a virtualenv where you'd have installed the "dev" dependencies, using:
Important: This project is, and should stay compatible with Python 2.6, 2.7 and Python 3.5+ up to 3.9, to keep the same Python compatibility that
Improving or fixing
skyfield-data will require you to have at least a virtualenv with
tox installed on it.
We'll ask you to add tests along your patch, to make sure that no regression or bug would be introduced by your patch or further ones.
To make a quick'n'dirty test, inside your "tox-ready" virtualenv, run:
to launch the Python 2.7 and Python 3.5+ test jobs.
If you want to test your branch against Python 2.6, you'll have to setup a Python 2.6-ready tox environment, by doing something similar to:
sudo apt install python2.6 python2.6-dev # dev headers to compile numpy mkvirtualenv TOX26 --python=`which python2.6` # You will activate this venv with `workon TOX26` pip install tox tox -c tox-py26.ini
Known issues: on Ubuntu, you may be unable to build numpy at this point, due to misplaced C header files in your system. I've had hard times on Ubuntu, but your mileage may vary.
If you don't want to or can't install Python 2.6 requirements, you'll have to rely on the Online CI jobs by Circle-CI.
Online CI with Travis & Circle-CI
The online CI is done by two services:
If either one of them is failing, your PR won't be merged.
de421.bspis provided by the Jet Propulsion Laboratory,
finals2000A.allis provided by the International Earth Rotation and Reference Systems Service.
This Python Package code is published under the terms of the MIT license. See the
COPYING file for more details.
Download the file for your platform. If you're not sure which to choose, learn more about installing packages.
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|Filename, size skyfield_data-3.0.0-py2.py3-none-any.whl (16.9 MB)||File type Wheel||Python version py2.py3||Upload date||Hashes View|
|Filename, size skyfield-data-3.0.0.tar.gz (16.9 MB)||File type Source||Python version None||Upload date||Hashes View|
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