Pointing Correction

While individual spacecraft align themselves on orbit using star tracker observations, a refined correction using stellar positions must be applied to allow for precise data reprojection and merging later in the pipeline.

Concept

The pointing correction is carried out by the thuban package, with a module within the punchbowl calling this code.

Applying correction

The correction is carried out primarily in the punchbowl.level1.alignment.align_task function:

punchbowl.level1.alignment.align_task(data_object: NDCube, distortion_path: str | None, mask: Callable | None = None, pointing_shift: tuple[float, float] = (0, 0)) → NDCube

Determine the pointing of the image and updates the metadata appropriately.

Parameters:

• data_object (NDCube) – data object to align

• mask (Callable | None) – function accepting coordinates and returning them only if they are not masked out

• distortion_path (str | None) – path to a distortion model

• pointing_shift (tuple[float, float]) – offset to pre-apply to the pointing to account for boresight to satellite-x shift

Returns:

a modified version of the input with the WCS more accurately determined

Return type:

NDCube

If you wish to incorporate this as a Prefect task in a custom pipeline, using something like the punchbowl.level1.alignment.align_task is recommended.