Potentially Visualize HiPS surveys with VisIVO/CARTA

Investigate how to interact with HiPS services through VisIVO/CARTA tool in order to access and visualize hierarchical tiling of sky regions at finer and finer spatial resolution which facilitates a progressive view of a survey, and supports multi-resolution zooming and panning;

Potential implementation of functionality to allow users to query HiPS2fits services in order to generate FITS images cutouts of arbitrary size and resolution from a given HiPS.

Notes from 4122:
The idea is to have a number of HiPS mirrors with a HiPS2FITS service co-located. The CARTA frontend will send requests to CARTA backend servers only accessing the API endpoints, rather than the web interface. We plan to integrate the UI into CARTA and will provide users with a limited set of options to tune, rather than providing the full set of API options.

The use case we are looking at in the first instance is:

• user loads a radio image
• user finds a region of interest
• user clicks the "HIPS query" button and it presents a list of available surveys and a pre-filled set of WCS parameters (based on the region of interest)
• user clicks "fetch", and the CARTA backend process fetches the FITS file and opens it (actually just using the fitsio HTTP functionality). From then on it behaves like any other image in CARTA.