Alignment

Limitations of run_align recipes

The esorex implementation of the alignment procedure (implemented in the pymusepipe.prep_recipes_pipe.PipePrep.run_align_bydataset()) for multiple object exposures suffers from some severe limitations:

• It does not perform absolute astrometry, but merely fixes the astrometry of subsequent exposures to the WCS of the first one. This is problematic for comparison of MUSE data with external datasets.

• It works by finding and matching point sources across white light images from multiple exposures. This requires the images to contain a sufficient number of point sources. Moreover, in case of mosaics, is requires the overlap region between different MUSE pointings to contain a sufficient number of point sources. In practice, this requirement is very limiting.

Pymusepipe provides the pymusepipe.align_pipe() module to overcome both these limitations.