This data is associated with M.E. Jarvis et al. 2021, MNRAS, 503, 1780, "Quasar Feedback Survey: Discovering hidden Radio-AGN and their connection to the host galaxy ionised gas". Also available on the pre-print archive: arxiv.org/abs/2103.00014
This dataset contains all of the in-band spectral index maps (C-band; 4-8GHz) images for the 40 of the 42 quasars that were studied in this work and that have the necessary data (see paper for details). There is also an error map corresponding to each spectral index map.
The details of how these maps were created from the raw datasets are described in the paper. The file format and meta-data stored in the header follow the astronomical standard fits format.