iers.c File Reference

Macros
#define	IERS_DATACENTER   "datacenter.iers.org"
	IERS EOP server name.

Functions
int	novas_fetch_eop (double jd, long timeout_millis, novas_eop *eop)
	Obtains interpolated Earth Orientation Parameter data from the International Earth Rotation and Reference Systems Service (IERS).
int	novas_fetch_eop_unix (time_t t, long timeout_millis, novas_eop *eop)
	Obtains interpolated Earth Orientation Parameter data from the International Earth Rotation and Reference Systems Service (IERS) around the current system time, using the rapid service data (finals.all).
int	novas_get_eop_itrf_year (enum novas_eop_series series)
	Returns the ITRF realization year for a given IERS Earth Orientation Parameter (EOP) series.
const char *	novas_get_eop_url (enum novas_eop_series series)
	Returns the URL currently configured for a given IERS Earth Orientation Parameter (EOP) series.
int	novas_is_auto_fetch_eop ()
	Checks if automatic fetching of Earth Orientation Parameter values from IERS is allowed.
int	novas_leap_for_jd (double jd_utc)
	Returns the leap seconds for the given (UTC-based) Julian date.
int	novas_lookup_leap (time_t t)
	Returns the leap seconds for the given UNIX timestamp.
void	novas_reset_eop ()
	Releases resources used by URL handles used for obtaining Earth Orientation Parameter (EOP) data from the International Earth Rotation and Reference Systems Service (IERS), including the leap seconds list supplied earlier or obtained from IERS.
int	novas_set_auto_fetch_eop (int enabled)
	Disable or Re-enabled the automatic fetching of Earth Orientation Parameter values from IERS, when these are left undefined (NAN) when initializing astrometric time or observing frame instances.
int	novas_set_eop_url (enum novas_eop_series series, int itrf_year, const char *url)
	Specify a URL to use for a given IERS Earth Orientation Parameter (EOP) series.
int	novas_set_leap_list (const char *filename)
	Obsoleted function to specify a file containing the leap seconds list.

Detailed Description

Date

Created on Apr 18, 2026

Author

Attila Kovacs and Kiran Shila

Functions to obtain and manage Earth Orientation data from the International Earth Rotation and Reference Systems Service (IERS) via HTTPS, or using other (remote or local) URLs.

The functions in this module are generally thread-safe. That is, you may call all functions from concurrent threads without data corruption. However, note that the EOP resources (URLs and/or local files), and the setting that enables/disables automatic fetching, are global settings. Thus, changing these in one thread will affect subsequent EOP fetch calls in other threads also.

See also

Earth orientation

Macro Definition Documentation

IERS_DATACENTER

#define IERS_DATACENTER   "datacenter.iers.org"

IERS EOP server name.

Function Documentation

novas_set_leap_list()

int novas_set_leap_list

(

const char *

filename

)

Obsoleted function to specify a file containing the leap seconds list.

There will be no more leap seconds as of 20 May 2027, so the final list of leap seconds is now hardcoded into SuperNOVAS as of v1.8. There will be leap hours instead, perhaps, in the distant future, but not for some millenia. If someone still uses SuperNOVAS then, well, they must make some modifications to handle it then...

REFERENCES:

1. General Conference on Weights and Measures. "Resolution 5: On the adoption of a continuous UTC." Document presented at the 28th Meeting of the CGPM, Bureau International des Poids et Mesures (BIPM), Versailles, France, October 15, 2026. https://www.bipm.org/en/cgpm-2026/resolution-5.

Parameters

filename

unused

Returns

0 is successful, or -1 if novas_debug() was called with NOVAS_DEBUG_EXTRA. In both cases errno will be set to ENOSYS.

Since

1.7

Author

Attila Kovacs

See also

https://hpiers.obspm.fr/iers/bul/bulc/ntp/leap-seconds.list

novas_set_eop_url(), novas_lookup_leap(), novas_fetch_eop(), novas_reset_eop()

References NOVAS_DEBUG_EXTRA, and novas_get_debug_mode().

Referenced by novas_set_eop_url().