Suppress erfa warnings for future times

[bmorris3]

Methods for synthetic datamodels like create_wfi_image generate metadata (create_meta) with exposures (create_exposure). Exposures contain times represented with astropy.time.Time objects, which have limited support for times sufficiently far in the future. This stems from uncertainty due to upcoming leap seconds, which may (or may not) be added between now and far-ish future times. Far-ish future times can be initialized without a problem in some formats/scales, but if you translate them to some other formats, you get an ERFA warning about a "dubious year", like this:

In [1]: from astropy.time import Time

In [2]: Time(1893456000, format='unix')  # no problems
Out[2]: <Time object: scale='utc' format='unix' value=1893456000.0>

In [3]: Time(1893456000, format='unix').iso  # problems
/Users/bmmorris/miniconda3/envs/jdaviz-only/lib/python3.10/site-packages/erfa/core.py:154: ErfaWarning: ERFA function "d2dtf" yielded 1 of "dubious year (Note 5)"
  warnings.warn('ERFA function "{}" yielded {}'.format(func_name, wmsg),
Out[3]: '2030-01-01 00:00:00.000'

The unix time chosen in the example above is the upper limit on the randomly drawn times used by roman_datamodels:

roman_datamodels/src/roman_datamodels/random_utils.py

Lines 42 to 44 in 086dd88

	def generate_utc_timestamp():
	# Random timestamp between 2020-01-01 and 2030-01-01
	return generate_float(1577836800.0, 1893456000.0)

so the later randomly drawn times within the range will throw an erfa warning. We can dodge the warning by suppressing it directly or by changing the time range. Since the time range is meant to mimic Roman's mission duration, I opted for the former, and put in a switch (ignore_erfa_warnings) to recover the old behavior.

This PR is in support of spacetelescope/jdaviz#1822.

[WilliamJamieson]

These changes look good to me. However, do you mind adding a changelog entry for this.

[WilliamJamieson]

Note, this is part of a solution to #129.

[PaulHuwe]

LGTM

[codecov]

Codecov Report

Patch coverage: 87.50% and project coverage change: +0.01 🎉

Comparison is base (086dd88) 76.88% compared to head (cda4d45) 76.89%.

❗ Current head cda4d45 differs from pull request most recent head 7f84b9b. Consider uploading reports for the commit 7f84b9b to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #138      +/-   ##
==========================================
+ Coverage   76.88%   76.89%   +0.01%     
==========================================
  Files          17       17              
  Lines        2167     2173       +6     
==========================================
+ Hits         1666     1671       +5     
- Misses        501      502       +1     

Impacted Files	Coverage Δ
src/roman_datamodels/random_utils.py	95.37% <87.50%> (-0.71%)	⬇️

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