## Compatibility between FITS and GILDAS

The notable projections supported by GILDAS are summarized in the Table 2.

Table 2: List of the projections implemented in GILDAS and subject to export or import to/from FITS data format. The top group was defined in the AIPS memo 27, the middle group in the memo 46, and the bottom group in the CG02 paper.
Name | FITS | GILDAS | Note
Gnomonic | TAN | gnomonic | Full compatibility GILDAS/FITS
Slant orthographic | SIN | orthographic | Basic compatibility (GILDAS does not implement the additional SIN projection parameters)
Zenithal equidistant | ARC | azimuthal | Full compatibility GILDAS/FITS
North Celestial Pole | NCP | ncp | Deprecated in FITS, kept in GILDAS as this would require additional projection parameters of the SIN projection
Stereographic | STG | stereographic | Full compatibility GILDAS/FITS since aug23 (see section 2.5)
Hammer-Aitoff | AIT | aitoff | Compatibility GILDAS/FITS as long as the reference is on the Equator
Global-Sinusoidal | GLS | radio | Compatibility GILDAS/FITS but deprecated in FITS, translated to SFL with translation
Sanson-Flamsteed | SFL | sfl | Full compatibility GILDAS/FITS since oct23 (see section 2.8)

Subsections

- Direct compatibility
- Incompatibilities
- The GLS/radio projection in details
- The Hammer-Aitoff case