celerity 0.2.0

Celerity is a lightweight, zero-dependency and type-safe Python library for astronomical calculations.

Celerity

Celerity is a lightweight, research-grade, zero-dependency type-safe Python library for astronomical calculations to plan your observations. It's only dependency is the Python 3.11+ standard library.

It has been designed to be independent of any other popular astronomical libraries, with a focus on providing a simple and intuitive API for performing common astronomical calculations.

N.B. This project is currently in the early stages of development and is not yet ready for production use.

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Usage

Installation

Celerity can be installed using pip:

pip install celerity

or poetry:

poetry add celerity

API

The API has been designed to be written in an idiomatic and natural way for English speakers, as well as idiomatic to Python.

It has been specifically designed to only depend on the core set of Python modules, such that it is not strictly dependent on other popular astronomical libraries, e.g., astropy (although it can compliment the usage of these libraries).

It's important to note that the API does not perform string parsing of times and coordinates, but instead requires the user to provide the correct data types. This is to ensure that the API is type-safe and that the user is aware of the data types being used at all times.

For example, to find out the horizontal coordinate for the star Betelgeuse on the 14th May 2021 at 12:00 UTC, at Mauna Kea, Hawaii, you would write:

from datetime import datetime, timezone

from celerity import Observer, Time

# Mauna Kea, Hawaii:
observer = Observer(
    latitude=19.82,
    longitude=-155.47,
    elevation=4205,
)

# Time of observation in UTC:
time = Time(
    when=datetime(2021, 5, 14, 12, 0, 0, tzinfo=timezone.utc)
)

# Provide a Sky target in equatorial coordinates at epoch J2000:
betelgeuse = { ra: 88.792938, dec: 7.407064 }

# Observe the target:
betelgeuse = observer.at(time).observe({ ra: 88.792938, dec: 7.407064 })

# Get the horizontal coordinates:
{ alt, az } = betelgeuse.altAz()

# What is the Local Sidereal Time at the time of observation?
lst = observer.at(time).LST()

# What is the Julian Date at the time of observation?
jd = observer.at(time).JD()

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Package Development

Project Requirements

• Python 3.11.*
• Docker.
• Docker Compose.
• Poetry for Python package and environment management.

Installing Dependencies

The Celerity project manages Python package dependencies using Poetry. You'll need to follow the instructions for installation there.

Then you can start a shell session with the new environment with:

$ poetry shell

N.B. For development with vscode you will need to run the following command:

$ poetry config virtualenvs.in-project true

This will installed the poetry .venv in the root of the project and allow vscode to setup the environment correctly for development.

To start development, install all of the dependencies as:

$ poetry install

N.B. Ensure that any dependency changes are committed to source control, so everyone has a consistenct package dependecy list.

Local Development

The Celerity development stack can be built with the following docker compose command, with the $INSTALL_DEV build environment argument*.

$ docker compose -f local.yml build --build-arg INSTALL_DEV="true"

* This is required to install the development dependencies in the container.

Then start the development stack with a running shell session with:

$ docker compose -f local.yml run app bash

N.B. The docker compose command will build the development stack if it has not been built already.

Running Tests

To run the tests, please ensure you have followed the steps for building the development server:

The Celerity development stack can be built with the following docker compose command, with the $INSTALL_DEV build environment argument*.

$ docker compose -f local.yml build --build-arg INSTALL_DEV="true"

You can then run the pytest suite using the following command:

$ docker compose -f local.yml exec api pytest