New SJICubeSequence Class

[DanRyanIrish]

The development of an SJICubeSequence class would provide a few important benefits. Firstly, it would enable multiple SJI files to be read into a single object, say if a OBS was split over two files due an eclipse, or if a user wanted to combine data from different campaigns using the same OBS number. Secondly, it would enable an SJICube to be broken out into a sequence of single images, each with its own WCS. This would enable fine-scale pointing corrections to be made on a frame by frame basis, but still give users an object that they could use as a single cube.

Proposed Implementation

• SJICubeSequence would be subclassed from NDCubeSequence
• As SJI data is always 3D (unlike spectrograph data), the __getitem__ method would be over-ridden. If the dimensionality of the sequence was 3D, i.e. all sub-cubes were 2D, normal slicing would be implemented. If the dimensionality is 4D, i.e. sub-cubes are 3-D, the index_as_cube slicing property would be called. This could also be determined by whether there was a common axis set.
• A new section of the read_iris_sji_level2_fits would be added to handle multiple files and return a SJICubeSequence.