point_map.fits uses RING ordering

[delucchi-cmu]

Bug report

The provided point map uses NESTED, and everywhere in hipscat interprets the ordering as NESTED, but healpy writes, by default, that the pixels are in RING ordering.

We should specify on fits writing that we're using NESTED ordering.

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• I have described the situation in which the bug arose, including what code was executed, information about my environment, and any applicable data others will need to reproduce the problem.
• I have included available evidence of the unexpected behavior (including error messages, screenshots, and/or plots) as well as a descriprion of what I expected instead.
• If I have a solution in mind, I have provided an explanation and/or pseudocode and/or task list.

[delucchi-cmu]

Closed by #273