heyoka.eop_data

heyoka.eop_data#

class heyoka.eop_data#

EOP data class.

Added in version 7.3.0.

This class is used to manage and access Earth orientation parameters data.

Note

A tutorial illustrating the use of this class is available.

Methods

__init__(self)

Default constructor.

fetch_latest_iers_long_term()

Fetch the latest IERS EOP long-term data.

fetch_latest_iers_rapid([origin, filename])

Fetch the latest IERS EOP rapid data.

Attributes

identifier

EOP data identifier.

table

EOP data table.

timestamp

EOP data timestamp.
__init__(self)#

Default constructor.

The default constructor initialises the EOP data with a builtin copy of the finals2000A.all rapid data file from the IERS datacenter.

Note that the builtin EOP data is likely to be outdated. You can use functions such as fetch_latest_iers_rapid() to fetch up-to-date data from the internet.

static fetch_latest_iers_long_term() → eop_data#

Fetch the latest IERS EOP long-term data.

This function will download from the IERS datacenter the latest EOP long-term datafile, from which it will construct and return an eop_data instance.

The file downloaded by this function is eopc04_20.1962-now.csv, which contains the IAU2000A EOP data from 1962 up to (roughly) the present time. Note that long-term data does not contain predictions for the future.

Note

This function will release the global interpreter lock (GIL) while downloading.

Returns:

an eop_data instance constructed from the remote file.

static fetch_latest_iers_rapid(origin: str = 'usno', filename: str = 'finals2000A.all') → eop_data#

Fetch the latest IERS EOP rapid data.

This function will download one the latest IERS EOP rapid data files, from which it will construct and return an eop_data instance.

origin indicates the datacenter from which the file will be downloaded, and its possible values are "usno" (indicating the US Naval Observatory) and "iers" (indicating the IERS datacenter).

The filename argument specifies which EOP data file will be downloaded. Its possible values are:

  • "finals2000A.all",

  • "finals2000A.daily",

  • "finals2000A.daily.extended",

  • "finals2000A.data",

for the usno datacenter, and

  • "finals.all.iau2000.txt",

  • "finals.daily.iau2000.txt",

  • "finals.data.iau2000.txt",

for the iers datacenter. These datafiles are updated frequently and they contain predictions for the future. They differ from each other mainly in the timespans they provide data for. For instance, finals2000A.all and finals.all.iau2000.txt contain several decades worth of data, while finals2000A.daily and finals.daily.iau2000.txt contain only the most recent data.

Note that there is considerable overlap between the USNO and IERS data files. For instance, at any given time, finals2000A.all and finals.all.iau2000.txt are expected to contain exactly the same data. The ability to fetch the same data from multiple origins is provided in order to improve resilience against transient network issues.

Please refer to the documentation on the USNO and IERS websites for more information about the content of these files.

Note

This function will release the global interpreter lock (GIL) while downloading.

Added in version 7.6.0: The origin function parameter.

Parameters:

  • origin – the datacenter to use for the download.

  • filename – the file to be downloaded.

Returns:

an eop_data instance constructed from the remote file.

Raises:

ValueError – if origin or filename is invalid.

property identifier#

EOP data identifier.

A string uniquely identifying the source of EOP data.

Return type:

str

property table#

EOP data table.

This is a structured NumPy array containing the raw EOP data. The dtype of the returned array is eop_data_row.

Return type:

numpy.ndarray

property timestamp#

EOP data timestamp.

A timestamp in string format which can be used to disambiguate between different versions of the same dataset.

The timestamp is inferred from the timestamp of the files on the remote data servers.

Return type:

str

Contents