find_optimal_celestial_wcs

reproject.mosaicking.find_optimal_celestial_wcs(input_data, hdu_in=None, frame=None, auto_rotate=False, projection='TAN', resolution=None, reference=None, negative_lon_cdelt=None)

Given one or more images, return an optimal WCS projection object and shape.

This currently only works with 2-d images with celestial WCS.

Parameters:

input_dataiterable

One or more input data specifications to include in the calculation of the final WCS. This should be an iterable containing one entry for each specification, where a single data specification is one of:

• The name of a FITS file as a str or a pathlib.Path object

• An HDUList object

• An image HDU object such as a PrimaryHDU, ImageHDU, or CompImageHDU instance

• A tuple where the first element is an Numpy array shape tuple and the second element is either a BaseLowLevelWCS, BaseHighLevelWCS, or a Header object

• A tuple where the first element is a ndarray and the second element is either a BaseLowLevelWCS, BaseHighLevelWCS, or a Header object

• An NDData object from which the .data and .wcs attributes will be used as the input data.

• A BaseLowLevelWCS object with array_shape set or a BaseHighLevelWCS object whose underlying low level WCS object has array_shape set.

If only one input data needs to be provided, it is also possible to pass it in without including it in an iterable.

hdu_inint or str, optional

If input_data is a FITS file or an HDUList instance, specifies the HDU to use.

framestr or BaseCoordinateFrame

The coordinate system for the final image (defaults to the frame of the first image specified).

auto_rotatebool

Whether to rotate the header to minimize the final image area (if True, requires shapely>=1.6 to be installed).

projectionstr

Three-letter code for the WCS projection.

resolutionQuantity

The resolution of the final image. If not specified, this is the smallest resolution of the input images.

referenceSkyCoord

The reference coordinate for the final header. If not specified, this is determined automatically from the input images.

negative_lon_cdeltbool or str, optional

Whether the CDELT value for the longitude coordinate should be negative (True) or positive (False), or determined automatically ('auto'). For astronomical observations of the sky CDELT is usually negative, while for coordinate systems used in solar physics this is usually positive. If this is 'auto', the value will be True if the first four characters for CTYPE for the longitude is RA--, GLON, ELON, HLON, or SLON, and False otherwise. The default is currently True, and will become 'auto' in future.

Returns:

wcsWCS

The optimal WCS determined from the input images.

shapetuple

The optimal shape required to cover all the output.