Switch External Trigger workflow to use multi-ordered sky maps when possible

There has been work to enable the use of MOC style sky maps when calculating the sky map overlap, meaning we no longer need to rely on flattening sky maps for the RAVEN workflow (ligo-raven/merge_requests/72). Preliminary calculations comparing the speeds of these algorithms show an improvement of 20-100x based on the method (MOC-MOC, MOC-flattened). There are many more reductions in latency that will result from this work, including no longer having to wait for a flattened GW sky map, shorter times to produce GRB sky maps, and quicker transfer speeds due to smaller MOC files.

This work will require the following changes to fully implement:

• Update to the latest ligo-raven version once released
• Default to load .multiorder.fits GW sky maps
• Default Swift GRB events (i.e. from GCN, not Targeted search) to pass RA/dec rather than wait for sky map to be created (apply EXT_SKYMAP_READY when RA/dec available)
• Create MOC GRB sky maps
• Use mhealpy to create combined sky map

See the documentation for mhealpy for tools for MOC sky maps.

changed milestone to %O4

added External Triggers Sky Maps labels

assigned to @brandon.piotrzkowski and @naresh.adhikari

changed the description

marked the checklist item Update to the latest ligo-raven version once released as completed

mentioned in issue #440 (closed)

mentioned in merge request !864 (closed)

unassigned @naresh.adhikari

mentioned in merge request !904 (merged)

marked the checklist item Default to load .multiorder.fits GW sky maps as completed

marked the checklist item Default Swift GRB events (i.e. from GCN, not Targeted search) to pass RA/dec rather than wait for sky map to be created (apply EXT_SKYMAP_READY when RA/dec available) as completed

mentioned in issue #413 (closed)

added RAVEN Priority label

set weight to 10

closed with merge request !904 (merged)

closed with commit 28a01c2d