FITS Astronomy Data (.fits / .fit / .fts)
.fits.fit.ftsNASA, ESA, astronomical observatories, telescope CCD cameras, and astrophysics pipelines
What it is
Flexible Image Transport System (FITS), the standard open format for astronomical data. AltaiPlot reads Primary HDU header cards and extracts 1D spectrum or 2D image data directly using big-endian NumPy decoders without heavy external dependencies.
Who produces it
Astronomers, astrophysicists, and astrophotographers analyzing spectral lines, light curves, and telescope sensor readouts.
What we read / what we don't read
What we read
- Primary HDU 1D spectrum and time-series data
- Primary HDU 2D image data arrays (flattened into columns)
- Linear 1D wavelength/time axis reconstruction via CRVAL1, CDELT1, and CRPIX1 header cards
- Big-endian integer and floating-point data types (BITPIX = 8, 16, 32, -32, -64)
What we don't read
- Extension HDUs (BINTABLE or image extensions beyond the Primary HDU)
- Non-linear World Coordinate System (WCS) projections
- Data arrays with more than 2 dimensions (NAXIS > 2)
How to import it into AltaiPlot
- Open AltaiPlot and drag your .fits, .fit, or .fts file onto the window, or use File → Import.
- AltaiPlot verifies the FITS 2880-byte header block structure and extracts the Primary HDU data.
- Preview the reconstructed X-axis (if WCS cards exist) and intensity/flux columns.
- Click Import.
Auditability note: this page's capability claims are sourced fromresources/python/app_sidecar.py:804 — see the full format list for every extension AltaiPlot recognizes.