When iers_degraded_accuracy = error, Astropy reports a warning and not an error (in coordinates)

Description

iers_degraded_accuracy can be set to "error", "warn" or "silent".

iers_degraded_accuracy = error has the same behavior as iers_degraded_accuracy = warn

Expected behavior

Expected behavior is log error instead of warning and an uncatched IERSRangeError . As documented here https://docs.astropy.org/en/stable/utils/iers.html

iers_degraded_accuracy:
Some time conversions like UTC -> UT1 require IERS-A Earth rotation data for full accuracy. In cases where full accuracy is not required and downloading the IERS-A is not possible or desired (for instance running on a cluster) then this option can be set to either 'warn' or 'ignore'. The default is 'error' which will raise an exception if full accuracy is not possible for a time conversion, 'warn' will issue a warning, and 'ignore' will ignore the problem and use available IERS-B data.

How to Reproduce

astropy.utils.iers.conf.iers_degraded_accuracy = "error"
t = Time("2016:001")
t.ut1

Versions

Python 3.10.12 (main, Nov 20 2023, 15:14:05) [GCC 11.4.0]
astropy 6.0.0
Numpy 1.26.2
pyerfa 2.0.1.1
Scipy 1.11.4
Matplotlib 3.8.2

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Are you sure that is going to raise anything? I tried your code with latest dev version and there is not even a warning.

We do test for the config behavior here and it seems to work both in CI and locally:

astropy/astropy/utils/iers/tests/test_iers.py

Lines 460 to 463 in ac2427c

    
           # Default is to raise an error 
        
           match = r"\(some\) times are outside of range covered by IERS table" 
        
           with pytest.raises(iers.IERSRangeError, match=match): 
        
               (now + 100 * u.day).ut1

Sorry, indeed my example was wrong. I need to post a more elaborate example, that gives only warning and does not stop. This is the case where internet is not enabled and times are outside of range covered by IERS table.

import astropy.units as u
import astropy

astropy.utils.data.clear_download_cache()
astropy.utils.data.conf.allow_internet = False
astropy.utils.iers.conf.iers_degraded_accuracy = "error"

time = Time("2024-02-29T17:53:03.605", format="isot", scale="utc")
x = np.array([1, 0, 0])
y = np.array([0, 1, 0])
z = np.array([0, 0, 1])
itrs = ITRS(CartesianRepresentation(x * u.m, y * u.m, z * u.m), obstime=time)
gcrs = itrs.transform_to(GCRS(obstime=time))

Running this example, I receive some warnings, but the execution doesn't stop and doesn't send any error for iers_degraded_accuracy:

WARNING: IERSWarning: failed to download https://datacenter.iers.org/data/9/finals2000A.all: <urlopen error URL https://datacenter.iers.org/data/9/finals2000A.all was supposed to be downloaded but allow_internet is False; if this is unexpected check the astropy.cfg file for the option allow_internet> [astropy.utils.iers.iers]
WARNING: IERSWarning: failed to download https://maia.usno.navy.mil/ser7/finals2000A.all: <urlopen error URL https://maia.usno.navy.mil/ser7/finals2000A.all was supposed to be downloaded but allow_internet is False; if this is unexpected check the astropy.cfg file for the option allow_internet> [astropy.utils.iers.iers]
WARNING: IERSWarning: unable to download valid IERS file, using local IERS-B [astropy.utils.iers.iers]
WARNING: Tried to get polar motions for times after IERS data is valid. Defaulting to polar motion from the 50-yr mean for those. This may affect precision at the arcsec level. Please check your astropy.utils.iers.conf.iers_auto_url and point it to a newer version if necessary. [astropy.coordinates.builtin_frames.utils]
WARNING: (some) times are outside of range covered by IERS table. Cannot convert with full accuracy. To allow conversion with degraded accuracy set astropy.utils.iers.conf.iers_degraded_accuracy to "warn" or "silent". For more information about setting this configuration parameter or controlling its value globally, see the Astropy configuration system documentation https://docs.astropy.org/en/stable/config/index.html. Assuming UT1-UTC=0 for coordinate transformations. [astropy.coordinates.builtin_frames.utils]

@maxnoe

Thank you very much for the complete example. Turns out the bug is in coordinates, not utils.iers. The warnings you see are coming from https://github.com/astropy/astropy/blob/main/astropy/coordinates/builtin_frames/utils.py that has custom code to bypass your configs. I am not sure if this is intentional or oversight.

For example, in get_jd12 (but not the only place it happens):

astropy/astropy/coordinates/builtin_frames/utils.py

Lines 114 to 117 in 73df592

    
           try: 
        
               newtime = getattr(time, scale) 
        
           except iers.IERSRangeError as e: 
        
               _warn_iers(e)

And this is where the "polar motion" one happens and it does not check for config at all:

astropy/astropy/coordinates/builtin_frames/utils.py

Line 49 in 73df592

"Tried to get polar motions for times {} IERS data is "

A quick git blame points to @maxnoe and @taldcroft for some of the designs, so hopefully they can clarify or ping those who can.

I am pretty sure that I didn't touch any code directly related to the warning / error handling there.

Checking the blame, I just slightly changed the wording of the message there

@eteq

I think @eteq is also in the blame somewhere. 😸

Sorry for the noise, @maxnoe !

@pllim

@pllim no problem at all, our software also runs in cluster environments so this issue is definitely relevant to us

In the meantime, for the affected use case, you would have to catch those warnings yourselves and promote them to error using https://docs.python.org/3/library/warnings.html

@pllim

@pllim nice workaround thanks!

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When iers_degraded_accuracy = error, Astropy reports a warning and not an error (in coordinates) #16128

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	# Default is to raise an error
	match = r"\(some\) times are outside of range covered by IERS table"
	with pytest.raises(iers.IERSRangeError, match=match):
	(now + 100 * u.day).ut1

	try:
	newtime = getattr(time, scale)
	except iers.IERSRangeError as e:
	_warn_iers(e)

When iers_degraded_accuracy = error, Astropy reports a warning and not an error (in coordinates) #16128

Description

Description

Expected behavior

How to Reproduce

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github-actions commented on Feb 28, 2024

pllim commented on Feb 28, 2024

IlDordollano commented on Feb 29, 2024

pllim commented on Feb 29, 2024

maxnoe commented on Feb 29, 2024

pllim commented on Feb 29, 2024

maxnoe commented on Feb 29, 2024

pllim commented on Feb 29, 2024

IlDordollano commented on Feb 29, 2024

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