Extend TOAST/sotodlib pointing comparison

[keskitalo]

Check that TOAST and sotodlib assign same samples to same pixels given the same WCS configuration.

Unit tests will not pass until hpc4cmb/toast#894 is merged.

[tskisner]

Thanks for improving these tests. We can't merge this in until the upstream toast PR is merged and a new tag is made.

[keskitalo]

This is the comparison to current tip of toast3:

This is the map comparison after 1/2 pixel offset added to TOAST (note the different plotting scales):

[keskitalo]

Turns out that the 1/2 pixel offset was only needed before a recent crpix data type fix in so3g. I removed the offset from this PR.

@Bai-Chiang noticed that the exact weather parameters used in qpoint azel->radec conversion impact the TOAST/so3g agreement. SimGround now has a special so3g_compat_mode where the pointing conversion assumes typical Atacama weather just like so3g.

[Bai-Chiang]

Is this half pixel offset removed or not?

[keskitalo]

Here we create a geometry with non-integer center pixel. It is separate from TOAST applying an offset in translating between pixel numbers and pointing angles.

The half-pixel offset turned out to be not needed in TOAST.

[Bai-Chiang]

Also it's better change the default weather to "toco" in mlmapmaker

sotodlib/sotodlib/toast/ops/mlmapmaker.py

Line 205 in 9fd7beb

weather = Unicode("vacuum", help="Weather to assume when making maps")

and add so3g_compat_mode to workflow script

sotodlib/sotodlib/toast/workflows/sim_observe.py

Lines 103 to 108 in 9fd7beb

	toast.ops.SimGround(
	name="sim_ground",
	weather="atacama",
	detset_key="pixel",
	session_split_key="wafer_slot",
	enabled=False,

[keskitalo]

Excellent points! Implemented both.

We won't be able to merge this PR until there is a tagged version of TOAST with so3g_compat_mode.