astropy-iers-data

import astropy.time as atime import astropy.units as u from astropy.utils import iers import os # Ensure astropy-iers-data is installed for local data access # For demonstration, we'll try to prevent online download if possible. # In a real scenario, you might want auto_download=True for freshest data. # Temporarily set auto_download to False to ensure bundled data is preferred # (if astropy-iers-data is installed and current enough). # If astropy-iers-data is not present or too old, this might fail. original_auto_download = iers.conf.auto_download iers.conf.auto_download = False try: # Create a Time object that requires IERS data (e.g., UTC to TAI/TT conversion) t = atime.Time('2023-01-01 00:00:00', scale='utc', format='isot') # Access a property that triggers IERS data lookup, e.g., TT # This operation implicitly uses the IERS tables. tt_time = t.tt print(f"UTC Time: {t}") print(f"TT Time (using IERS data): {tt_time}") # Demonstrate using Earth rotation parameters (requires IERS data) xp_val = iers.IERS_A.pm_x(t.mjd).to(u.arcsec) yp_val = iers.IERS_A.pm_y(t.mjd).to(u.arcsec) print(f"Pole motion x (xp) at {t.iso}: {xp_val}") print(f"Pole motion y (yp) at {t.iso}: {yp_val}") print("Successfully accessed IERS data, likely from astropy-iers-data if auto_download was False.") except Exception as e: print(f"An error occurred, potentially indicating missing or outdated IERS data: {e}") finally: # Restore original auto_download setting iers.conf.auto_download = original_auto_download