File Input and Output

FITS Input

DISCO accepts standard FITS files conforming to the ALMA imaging output convention. The following header keywords are read and utilised:

Keyword	Usage
`CDELT2`	Pixel scale in degrees per pixel. The absolute value is multiplied by 3600 to yield arcseconds per pixel.
`BUNIT`	Flux density units. If `"JY/BEAM"`, the data are multiplied by 1 000 to convert to mJy/beam.
`BMAJ`, `BMIN`	Synthesised beam major and minor axes in degrees. Used for beam area computation, SNR scoring, inner radius estimation, beam homogenisation, and brightness temperature conversion.
`BPA`	Beam position angle in degrees. Used for beam kernel construction.
`RESTFRQ`	Rest frequency in Hz. Used for brightness temperature conversion. Fallback: searches `CRVAL3`/`CRVAL4` for a frequency axis; if absent, assumes 230 GHz.
`DATE-OBS`	ISO-T observation date string. Used for Gaia proper-motion epoch.
`MJD-OBS`	Modified Julian Date of observation. Fallback for `DATE-OBS`.
`NAXIS1`, `NAXIS2`	Image dimensions in pixels.
WCS keywords (`CTYPE1/2`, `CRPIX1/2`, `CRVAL1/2`, etc.)	Used for pixel ↔ ICRS coordinate transformations.

Multi-dimensional FITS cubes (e.g. with Stokes and frequency axes) are handled by numpy.squeeze, which collapses all degenerate axes to produce a 2D image.

CLI Output Files

The CLI pipeline writes the following files to <output_dir>/ for each processed group. All paths are relative to the group output directory.

Radial Profile Plot

Filename	Description
`RP_<group_name>.PNG`	Matplotlib figure (dpi=150, white background) showing normalised radial profiles for all images in the group, with the optimised geometry annotated in the title (inclination ± uncertainty, PA ± uncertainty). One line per FITS file, labelled by band if a `Band_N` token is present in the filename.

CSV Exports (`--csv on`)

Filename	Contents
`RP_<group_name>_global.csv`	Global geometric parameters. Columns: `parameter`, `value`, `uncertainty`. Parameters written: `Rout_arcsec`, `Rmin_arcsec`, `Inclination_deg`, `PA_deg`, `Ellipse_smaj_arcsec`, `Ellipse_smin_arcsec`, `Center_RA_deg`, `Center_Dec_deg` (if WCS available), `Gaia_pmRA_masyr`, `Gaia_pmDec_masyr`, `Gaia_match_arcsec` (if Gaia match found).
`RP_<group_name>_bands.csv`	Per-image metadata. Columns: `filename`, `snr`, `cx_pix`, `cy_pix`, `bmaj_arcsec`, `bmin_arcsec`, `peak_flux_mJyBeam`.
`RP_<group_name>_profile.csv`	Tabulated radial profile data. For each image (column group labelled by band): `R_<band>_arcsec`, `Flux_<band>_mJy`, `FluxNorm_<band>`, `FluxNormErr_<band>`. Rows correspond to radial bins; missing values are empty strings.

Debug Output (`--debug on`)

Filename	Contents
`debug_pipeline/<group_name>_debug_center_rout.png`	PNG (dpi=150) of the deprojected image of the reference file, with a white cross at the optimised centroid and a dashed cyan circle at the outer radius.

GUI Session Files

The GUI supports saving and restoring sessions as JSON files. The session file schema is:

{
  "filename": "<base FITS filename>",
  "params": {
    "cx": <float>,
    "cy": <float>,
    "incl": <float>,
    "pa": <float>,
    "rout": <float>,
    "fit_rmin": <float>,
    "fit_rmax": <float>
  },
  "timestamp": "<ISO-8601 string>",
  "pixelScale": <float>
}

On restore, the stored parameters are applied immediately and the referenced FITS file is reloaded from the upload directory via POST /load_local.

GUI FITS Downloads

Any pipeline output image type ("data", "deproj", "model", "residuals", "polar") can be downloaded as a FITS file via GET /download_fits?type=<type>. The returned FITS file carries the original header from the loaded FITS file.

GUI CSV Export

The handleDownloadCSV function in AnalysisDashboard.jsx produces a three-column CSV file (radial_profile.csv) with the following columns:

Column	Units	Source
`Radius [arcsec]`	arcsec	`profileData.radius`
`Intensity [Jy/beam]`	Jy/beam	`profileData.raw_intensity`
`Brightness Temp [K]`	K	`profileData.intensity`