astropy

FITS I/O with Astropy lets you open, parse, and modify FITS files and their headers using the `fits` module. Load data with `fits.open()`, access table or image data, update headers, and write changes back to disk efficiently.

Coordinate transformations use Astropy's `SkyCoord` object to convert positions between frames like ICRS, Galactic, and AltAz. Specify input coordinates and frame, then transform to your target frame with a single method call.

Astropy's units module attaches physical dimensions to numbers and performs unit-aware arithmetic automatically. Access physical constants via the constants module for calculations without manual conversion.

The Time class unifies diverse time formats—ISO, JD, MJD, Unix—into a single object, handles timezone conversions, and performs time arithmetic for scheduling observations and calculating exposure timing.

Astropy's cosmology module provides standard models to convert redshift to luminosity distance, compute age of the universe at a given z, and calculate comoving distances without implementing formulas manually.