Astropy: A Community Python Package for Astronomy (1307.6212v1)

Abstract: We present the first public version (v0.2) of the open-source and community-developed Python package, Astropy. This package provides core astronomy-related functionality to the community, including support for domain-specific file formats such as Flexible Image Transport System (FITS) files, Virtual Observatory (VO) tables, and common ASCII table formats, unit and physical quantity conversions, physical constants specific to astronomy, celestial coordinate and time transformations, world coordinate system (WCS) support, generalized containers for representing gridded as well as tabular data, and a framework for cosmological transformations and conversions. Significant functionality is under active development, such as a model fitting framework, VO client and server tools, and aperture and point spread function (PSF) photometry tools. The core development team is actively making additions and enhancements to the current code base, and we encourage anyone interested to participate in the development of future Astropy versions.

• The paper introduces Astropy as a cohesive Python package that standardizes astronomical data handling and analysis.
• It details core modules for managing physical units, time, celestial coordinates, and cosmological calculations with precision.
• The work emphasizes community-driven development and continuous integration to ensure robustness and future enhancements in astronomy research.

An Overview of the Astropy Package: A Community Python Resource for Astronomy

The Astropy package exemplifies collaborative, open-source development in the astronomical software community, presenting a concerted effort to create a cohesive set of tools for astronomers utilizing the Python programming language.

The core objective of Astropy is to standardize astronomy-specific functionality, avoiding the fragmentation seen in earlier efforts across different teams. As such, it covers a variety of needs, from managing data in domain-specific formats to providing sophisticated cosmological transformations.

Key Features and Capabilities

1. Units and Quantities: astropy.units offers comprehensive support for physical units, allowing users to define, convert, and manipulate units and quantities with seamless integration into scientific workflows.
2. Time and Dates: The astropy.time module provides robust support for different time scales and formats, crucial in astronomy for precise time conversions and handling of leap seconds.
3. Celestial Coordinates: astropy.coordinates enables manipulation and transformation of astronomical coordinates, supporting conversions between numerous coordinate systems, along with a flexible transformation graph for easy integration of new systems.
4. Data Structures: With support for tabular and gridded data through astropy.table and astropy.nddata, Astropy provides easy handling of complex data structures with metadata, essential for astronomical datasets.
5. Astronomical File Formats: The package supports standard file formats like FITS and VOTable, ensuring seamless read/write operations crucial for data interchange within the astronomy community.
6. World Coordinate Systems (WCS): Utilizing astropy.wcs, the package interacts with pixel-to-sky coordinate transformations, enabling precise spatial analysis in imaging data.
7. Cosmology Calculations: astropy.cosmology provides tools for representing various cosmological models and performing calculations of cosmological distances, volumes, and times, supporting a range of ΛCDM and alternative cosmologies.

Development and Community Approach

Astropy's development is highly collaborative, facilitated through GitHub, and prioritizes community involvement to ensure the interface aligns with user workflows. The project employs continuous integration practices to maintain code quality across platforms and Python versions. Its open-source nature and use of a permissive BSD license encourage wide adoption and community participation in bug reports and feature enhancements.

Implications and Future Directions

Astropy's structured approach to development ensures that it not only meets current needs but also facilitates rapid inclusion of new capabilities and adaptation to evolving research demands. Plans for future releases include better interoperability within Astropy components, improved representation of large datasets, and expanded support for additional astronomical protocols and data analysis tools.

Astropy represents a significant step towards unifying Python-based software tools for astronomers, encouraging consistent methodologies, and fostering a culture of collaboration and code sharing across the community. Its ongoing development ensures it remains responsive to the advancing requirements of astronomical research, making it an indispensable tool for the modern astronomer.