cutout_fits.cutout¶

Attributes¶

_

Classes¶

`SpatialIndex`	Start and end indices for spatial axes.
`SpectralIndex`	Start and end indices for spectral axes.
`StokesIndex`	Start and end indices for Stokes axes.

Functions¶

`cutout_beamtable`(→ astropy.io.fits.BinTableHDU)	Cut out a beam table
`format_shape`(→ str)	Produce a string representation of the shape of an cube
`get_cutout_parser`(→ argparse.ArgumentParser)
`get_cutout_shape`(→ tuple[int, Ellipsis])	Get the shape of a cutout
`get_file_parser`(→ argparse.ArgumentParser)
`get_spatial_indices`(→ SpatialIndex)	Get the start and end indices for spatial axes
`get_spectral_indices`(→ SpectralIndex)	Get the start and end indices for spectral axes
`get_stokes_indices`(→ StokesIndex)	Get the start and end indices for Stokes axes
`main`(→ None)
`make_cutout`(→ astropy.io.fits.HDUList)	Make a cutout of a FITS file
`make_slicer`(→ tuple[slice, Ellipsis])	Create a slicer for a given WCS, centre, radius, and frequency range
`update_header`(→ astropy.io.fits.Header)	Update the header to reflect the cutout

Module Contents¶

class cutout_fits.cutout.SpatialIndex¶

Bases: NamedTuple

Start and end indices for spatial axes.

start_ra_index¶: int | None

end_ra_index¶: int | None

start_dec_index¶: int | None

end_dec_index¶: int | None

end_dec_index: int | None¶: End index for Dec axis

end_ra_index: int | None¶: End index for RA axis

start_dec_index: int | None¶: Start index for Dec axis

start_ra_index: int | None¶: Start index for RA axis

class cutout_fits.cutout.SpectralIndex¶

Bases: NamedTuple

Start and end indices for spectral axes.

start_freq_index¶: int | None

end_freq_index¶: int | None

end_freq_index: int | None¶: End index for frequency axis

start_freq_index: int | None¶: Start index for frequency axis

class cutout_fits.cutout.StokesIndex¶

Bases: NamedTuple

Start and end indices for Stokes axes.

start_stokes_index¶: int | None

end_stokes_index¶: int | None

end_stokes_index: int | None¶: End index for Stokes axis

start_stokes_index: int | None¶: Start index for Stokes axis

cutout_fits.cutout.cutout_beamtable(hdu: astropy.io.fits.BinTableHDU, image_wcs: astropy.wcs.WCS, freq_start_hz: float | None = None, freq_end_hz: float | None = None) → astropy.io.fits.BinTableHDU¶

Cut out a beam table

Parameters:

hdu (fits.BinTableHDU) – HDU with the beam table
image_wcs (WCS) – WCS of the image that needs beams
freq_start_hz (float | None, optional) – Starting frequency cut in Hz. Defaults to None.
freq_end_hz (float | None, optional) – End frequnecy cut in Hz. Defaults to None.

Returns:

Cutout beam table

Return type:

fits.BinTableHDU

cutout_fits.cutout.format_shape(wcs: astropy.wcs.WCS, shape: tuple[int, Ellipsis]) → str¶

Produce a string representation of the shape of an cube

Parameters:

wcs (WCS) – Cube WCS
shape (tuple[int,...]) – Shape of the cube

Returns:

String representation of the shape

Return type:

str

cutout_fits.cutout.get_cutout_parser(parent_parser: bool = False) → argparse.ArgumentParser¶

cutout_fits.cutout.get_cutout_shape(wcs: astropy.wcs.WCS, slicer: tuple[slice, Ellipsis]) → tuple[int, Ellipsis]¶

Get the shape of a cutout

Parameters:

wcs (WCS) – WCS of the cutout
slicer (tuple[slice, ...]) – Slicer for the cutout

Returns:

Shape of the cutout

Return type:

tuple[int, …]

cutout_fits.cutout.get_file_parser(parent_parser: bool = False) → argparse.ArgumentParser¶

cutout_fits.cutout.get_spatial_indices(wcs: astropy.wcs.WCS, centre: astropy.coordinates.SkyCoord, radius: astropy.units.Quantity) → SpatialIndex¶

Get the start and end indices for spatial axes

Parameters:

wcs (WCS) – WCS for HDU
centre (SkyCoord) – Centre of cutout
radius (u.Quantity) – Radius of cutout

Returns:

start_ra_index, end_ra_index, start_dec_index, end_dec_index

Return type:

SpatialIndex

cutout_fits.cutout.get_spectral_indices(wcs: astropy.wcs.WCS, start_freq: astropy.units.Quantity | None = None, end_freq: astropy.units.Quantity | None = None) → SpectralIndex¶

Get the start and end indices for spectral axes

Parameters:

wcs (WCS) – WCS for HDU
start_freq (u.Quantify | None, optional) – Starting frequency. Defaults to None.
end_freq (u.Quantify | None, optional) – End frequency. Defaults to None.

Returns:

start_freq_index, end_freq_index

Return type:

SpectralIndex

cutout_fits.cutout.get_stokes_indices(wcs: astropy.wcs.WCS) → StokesIndex¶

Get the start and end indices for Stokes axes

Parameters:: wcs (WCS) – WCS for HDU
Returns:: start_stokes_index, end_stokes_index
Return type:: StokesIndex

cutout_fits.cutout.main() → None¶

cutout_fits.cutout.make_cutout(infile: str, outfile: str, ra_deg: float, dec_deg: float, radius_arcmin: float, freq_start_hz: float | None = None, freq_end_hz: float | None = None, overwrite: bool = False) → astropy.io.fits.HDUList¶

Make a cutout of a FITS file

Parameters:

infile (str) – Path to FITS file - can be a remote URL
outfile (str) – Path to output file - must be local
ra_deg (float) – Centre RA in degrees
dec_deg (float) – Centre Dec in degrees
radius_arcmin (float) – Cutout radius in arcminutes
freq_start_hz (float | None, optional) – Start frequency in Hz. Defaults to None.
freq_end_hz (float | None, optional) – End frequency in Hz. Defaults to None.
overwrite (bool) – Whether to overwrite the output file.

Returns:

Cutout HDUList

Return type:

fits.HDUList

cutout_fits.cutout.make_slicer(wcs: astropy.wcs.WCS, centre: astropy.coordinates.SkyCoord, radius: astropy.units.Quantity, start_freq: astropy.units.Quantity | None = None, end_freq: astropy.units.Quantity | None = None) → tuple[slice, Ellipsis]¶

Create a slicer for a given WCS, centre, radius, and frequency range

Parameters:

wcs (WCS) – WCS for HDU
centre (SkyCoord) – Centre of cutout
radius (u.Quantity) – Radius of cutout
start_freq (u.Quantity | None, optional) – Starting frequency. Defaults to None.
end_freq (u.Quantity | None, optional) – End frequnecy. Defaults to None.

Returns:

Tuple of slices for each axis - in numpy order

Return type:

Tuple[slice,…]

cutout_fits.cutout.update_header(old_header: astropy.io.fits.Header, slicer: tuple[slice, Ellipsis]) → astropy.io.fits.Header¶

Update the header to reflect the cutout

Parameters:

old_header (fits.Header) – Original header
slicer (tuple[slice, ...]) – Slicer for the cutout

Returns:

Cutout header

Return type:

fits.Header

cutout_fits.cutout._ = False¶