Convert ASDF to FITS Online Free & Fast

FAQ

Q1: Why would I convert ASDF to FITS instead of just sticking with ASDF?

A1: You typically convert when you need to interact with software or archives that primarily use FITS. Many legacy astronomical tools, observatory data pipelines, and journal submission requirements are still anchored in FITS. While ASDF is modern and powerful, FITS remains the de-facto standard for long-term archival and wide-scale data sharing within the astronomy community.

Q2: Will all my ASDF metadata be perfectly preserved when converting to FITS?

A2: No, probably not perfectly. ASDF allows for highly flexible, nested, and human-readable metadata structures with long keys. FITS headers are much more rigid, using 8-character keywords and a flatter structure. You'll likely need to either truncate ASDF keys, flatten nested metadata, or store complex metadata as JSON strings within FITS keywords, which means some loss of native structure and human-readability.

Q3: What's the easiest way to perform this conversion, especially for complex files?

A3: The easiest and most robust method is using Python with the astropy.io.asdf and astropy.io.fits libraries. These libraries handle many complexities automatically, especially if your ASDF file uses astropy.nddata objects. For very complex or custom ASDF structures, you might need to write specific Python code to extract and map data/metadata to FITS HDUs.

Q4: Can I convert FITS back to ASDF if needed?

A4: Yes, generally you can. astropy.io.fits can read FITS files, and the extracted data and header information can then be structured and written out as an ASDF file using astropy.io.asdf. The round trip is usually more straightforward going from FITS to ASDF in terms of data preservation due to ASDF's greater flexibility with structure and metadata.