The BIPM Time Department manages the calibration of time transfer systems used to generate UTC. Calibrations may be carried out by the BIPM, by the RMOs, by individual time laboratories or, in some cases, by other entities such as manufacturers. These pages give access to the calibration results and reports for all techniques contributing to UTC.

Starting 2015, calibrations in laboratories contributing to UTC follow specific guidelines. For more information please click on the Documentation tab above.

Current calibration results (available via the "Current files" tab above) are labelled with a calibration identifier (Cal_ID) to enable the process yielding the results to be traced. The Cal_ID is used to report calibration information in Section 5 of Circular T; an example is given here.

The calibration identifiers are of the form znnn-YYYY where

• z identifies the type of calibration;
• nnn is a number assigned by the BIPM;
• YYYY indicates the year (typically the start of the calibration exercise).

The types of calibration are:

• z = 0: For TWSTFT links, whatever the technique used for the link calibration. nnn then is the calibration identification of the ITU format.
• z = 1: For GNSS systems, with GNSS calibration campaigns under the supervision of the BIPM; nnn then identifies a report corresponding to a calibration trip; see details in the GNSS Guidelines.
• z = 2: For GNSS systems, calibrated with other techniques (e.g. manufacturer calibration, absolute calibration, or transfer using a calibrated link); nnn then identifies a report and is a sequential number within the year.
• z = 3: direct links, e.g. through RF cables or optical fibres; nnn then identifies a report and is a sequential number within the year.

Calibrations made before 2014 have been included in the current scheme by assigning a Cal_ID when a full report is available. The history of calibrations until 2014 can also be accessed in its original form through the "Archive" tab above.

Starting 2015, GNSS and TWSTFT calibrations in UTC contributing laboratories are organized as follows:

The GNSS calibration scheme is a hierarchical system.

The BIPM will organize the calibration of some laboratories (called "Group 1") in each Regional Metrology Organization, and the RMOs, together with these "Group 1" laboratories, will organize calibration campaigns for the other laboratories of their region (called "Group 2"). Guidelines will assure that the calibration processes will all be consistent with those implemented at the BIPM. See the GNSS Guidelines for more information. See a short description of the calibration procedure in the Readme file and a list of upcoming calibration exercises here.

The TWSTFT calibrations are organized by the TWSTFT stations contributing to UTC following the Guidelines for TWSTFT link calibrations.

Year	Cal_ID	Type of Calibration	Other info.	Version	Last updated
Year	Cal_ID	Type of Calibration	Other info.	Version	Last updated
2011	0211-2011	TW	CH		January 8, 2016
2011	0214-2011	TW	NIST		January 8, 2016
2011	0220-2011	TW	VSL		January 8, 2016
2012	0281-2012	TW	SU		April 8, 2015
2012	0284-2012	TW	CH	v1.0	January 7, 2016
2012	0284-2012	TW	CH	v2.0	December 12, 2017
2015	0295-2015	TW	VSL	v1.0	January 7, 2016
2015	0295-2015	TW	VSL	v2.0	December 12, 2017
2014	0374-2014	TW	Europe-IT		June 2, 2015
2014	0377-2014	TW	Europe-OP		June 2, 2015
2014	0380-2014	TW	Europe-ROA		June 2, 2015
2014	0381-2014	TW	Europe-SP		June 2, 2015
2014	0391-2014	TW	USNO		April 8, 2015
2015	0392-2015	TW	USNO		January 7, 2016
2015	0393-2015	TW	NIST	v1.0	August 26, 2015
2015	0393-2015	TW	NIST	v2.0	December 12, 2017
2016	0395-2016	TW	USNO	v1.0	October 11, 2016
2016	0395-2016	TW	USNO	v2.0	December 12, 2017
2016	0417-2016	TW	NIM		October 10, 2016
2016	0418-2016	TW	NTSC		October 10, 2016
2016	0434-2016	TW	IT		December 12, 2017
2016	0434-2016	TW	IT	v1.0	April 3, 2017
2016	0434-2016	TW	IT	v2.0	December 12, 2017
2016	0437-2016	TW	OP	v1.0	April 3, 2017
2016	0437-2016	TW	OP	v2.0	December 12, 2017
2016	0440-2016	TW	ROA	v1.0	April 3, 2017
2016	0440-2016	TW	ROA	v2.0	December 12, 2017
2016	0441-2016	TW	SP	v1.0	April 3, 2017
2016	0441-2016	TW	SP	v2.0	December 12, 2017
2017	0449-2017	TW	AOS	v1.0	August 16, 2017
2017	0449-2017	TW	AOS	v2.0	December 12, 2017
2017	0450-2017	TW	NPL	v1.0	August 16, 2017
2017	0450-2017	TW	NPL	v2.0	December 12, 2017
1993	1001-1993	CA	199305		April 8, 2015
2003	1001-2003	P3	NRC		April 8, 2015
2004	1001-2004	CA	200802		April 8, 2015
2005	1001-2005	P3	TL		April 8, 2015
2007	1001-2007	P3	DLR		April 8, 2015
2008	1001-2008	P3	PTB		April 8, 2015
2009	1001-2009	P3	SP		April 8, 2015
2010	1001-2010	P3	SG		April 8, 2015
2011	1001-2011	P3	TCC		April 8, 2015
2012	1001-2012	P3	ORB		April 8, 2015
2014	1001-2014	GPSP3C1	Initial-Group1-trip		April 25, 2018
2014	1001-2014	GPSP3	Initial-Group1-trip		August 1, 2016
2016	1001-2016	GPSP3C1	Group1-trip		October 24, 2017
2003	1002-2003	CA	200406		April 8, 2015
2004	1002-2004	CA	200803		April 8, 2015
2005	1002-2005	P3	NMIJ		April 8, 2015
2007	1002-2007	P3	IT		April 8, 2015
2008	1002-2008	P3	OP		April 8, 2015
2009	1002-2009	P3	TP		April 8, 2015
2010	1002-2010	P3	AUS		April 8, 2015
2005	1003-2005	P3	KRIS		April 8, 2015
2008	1003-2008	P3	CH		April 8, 2015
2009	1003-2009	P3	ONRJ		April 8, 2015
2005	1004-2005	CA	200804		April 8, 2015
2008	1004-2008	P3	ROA		April 8, 2015
2008	1005-2008	CA	201004		April 8, 2015
2006	1007-2006	CA	201002		April 8, 2015
2006	1008-2006	CA	201003		April 8, 2015
2007	1011-2007	CA	EIM		April 8, 2015
2010	1011-2010	P3	NPL		April 8, 2015
2011	1011-2011	P3	IFAG		April 8, 2015
2012	1011-2012	P3	ESTC		April 8, 2015
2016	1011-2016	GPSP3	BIM-UME-BOM-DMDM-IMBH-INRIM		January 17, 2017
2012	1012-2012	P3	ESTC		April 8, 2015
2016	1012-2016	GPSP3	DLR-METAS-VSL-BEV		October 7, 2016
2016	1012-2016	GPSP3	DLR-METAS-VSL-BEV	V2.0	March 16, 2018
2012	1013-2012	P3	NIM		April 8, 2015
2016	1013-2016	GPSP3	INRIM-SP		March 21, 2017
2017	1013-2017	GPSP3C1	NIMT-NMLS-VMI		September 27, 2017
2016	1014-2016	GPSP3	NTSC		July 5, 2017
2017	1014-2017	GPSP3C1	NPL-SMD		August 30, 2017
2016	1015-2016	GPSC1P3	BIRM		May 19, 2017
2017	1015-2017	GPSP3	DTAG		August 31, 2017
2016	1017-2016	GPSP3	NRC		January 18, 2017
2017	1017-2017	GPSP3C1	KRISS		September 28, 2017
2017	1018-2017	GPSP3	ORB		September 29, 2017
2016	1019-2016	GPSP3	ESTEC		April 27, 2017
2017	1020-2017	GPSP3C1	SASO	V1.0	February 1, 2018
2013	1101-2013	GPSP3	AOS-GUM		March 23, 2016
2015	1101-2015	GPSP3	ESOC		March 23, 2016
2016	1101-2016	GPSP3	CNES		September 15, 2016
2016	1101-2016	GPSP3	CNES	V2.0	March 27, 2018
2015	1102-2015	GPSP3	MIKES		March 23, 2016
2016	1102-2016	GPSP3	ZA		October 7, 2016
2017	1102-2017	GPSP3C1	TP	V1.0	January 30, 2018
2006	2001-2006	CA	SMU		April 8, 2015
2008	2001-2008	CA	BY		April 8, 2015
2009	2001-2009	CA	INPL		April 8, 2015
2011	2001-2011	CA	ONRJ		April 8, 2015
2012	2001-2012	CA	HKO		April 8, 2015
2013	2001-2013	CA	MTC		April 8, 2015
2014	2001-2014	CA	AOS		April 8, 2015
2015	2001-2015	CA	NIMB		January 26, 2016
2016	2001-2016	CA	UAE		January 9, 2017
2017	2001-2017	CA	ICE		August 17, 2017
2008	2002-2008	CA	KZ		April 8, 2015
2011	2002-2011	CA	SMD		April 8, 2015
2012	2002-2012	CA	HKO		February 25, 2014
2012	2002-2012	CA	IMBH		April 7, 2015
2013	2002-2013	CA	SASO		April 8, 2015
2014	2002-2014	CAP3	SIQ		April 8, 2015
2015	2002-2015	CA	CNMP		May 11, 2016
2016	2002-2016	GPSP3C1	INPL		June 1, 2018
2008	2003-2008	CATW	BEV		January 7, 2016
2011	2003-2011	CA	UA		April 8, 2015
2012	2003-2012	CA	KZ		May 6, 2015
2013	2003-2013	CA	UME		April 8, 2015
2014	2003-2014	CA	IMBH		April 7, 2015
2016	2003-2016	GPSP3C1	INPL		June 1, 2018
2017	2003-2017	GPSP3C1	NPLI		March 2, 2018
2017	2003-2017	GPSP3C1	NPLI	V2.0	April 5, 2018
2008	2004-2008	CA	BIM		April 8, 2015
2012	2004-2012	CA	IMBH		April 7, 2015
2014	2004-2014	CA	BOM		April 20, 2016
2016	2004-2016	CA	IMBH		January 13, 2017
2017	2004-2017	GPSP3C1	NPLI		March 2, 2018
2014	2005-2014	CA	IGNA	v1.0	April 4, 2018
2017	2005-2017	GPSP3C1	NPLI		February 26, 2018
2017	3001-2017	LK	JATC-NTSC	v1.0	January 3, 2018