CIRCULAR T 363 ISSN 1143-1393
2018 APRIL 11, 10h UTC
BUREAU INTERNATIONAL DES POIDS ET MESURES
THE INTERGOVERNMENTAL ORGANIZATION ESTABLISHED BY THE METRE CONVENTION
PAVILLON DE BRETEUIL F-92312 SEVRES CEDEX TEL. +33 1 45 07 70 70 tai@bipm.org

The contents of the sections of BIPM Circular T are fully described in the document " Explanatory supplement to BIPM Circular T "
available at https://webtai.bipm.org/ftp/pub/tai/other-products/notes/explanatory_supplement_v0.1.pdf

1 - Difference between UTC and its local realizations UTC(k) and corresponding uncertainties. From 2017 January 1, 0h UTC, TAI-UTC = 37 s.
Date 2018 0h UTC FEB 25 MAR 2 MAR 7 MAR 12 MAR 17 MAR 22 MAR 27 Uncertainty/ns Notes
MJD 58174 58179 58184 58189 58194 58199 58204 uA uB u
Laboratory k [UTC-UTC(k)]/ns
AOS (Borowiec) -4.6 -3.9 -2.9 -2.0 -0.8 -0.5 -0.1 0.5 3.3 3.3
APL (Laurel) 3.3 2.6 3.3 4.3 0.6 1.2 1.6 2.0 10.9 11.1
AUS (Sydney) 182.5 176.9 177.9 168.2 157.5 152.6 138.7 0.4 6.3 6.3
BEV (Wien) -10.5 -6.4 5.4 -2.6 0.2 -9.3 -8.3 0.4 3.1 3.1
BIM (Sofiya) - - - - - - -
BIRM (Beijing) 22.4 24.3 19.9 17.5 17.1 15.8 15.1 0.5 3.0 3.0
BOM (Skopje) 138.3 143.3 141.6 137.6 -7.0 -33.0 -59.6 1.5 8.1 8.2 (1)
BY (Minsk) 1.5 1.1 0.8 2.3 2.3 1.9 0.7 1.5 9.7 9.8
CAO (Cagliari) - - - - - - -
CH (Bern-Wabern) 35.4 33.9 26.7 23.3 19.7 15.4 10.0 0.4 2.1 2.1
CNES (Toulouse) 11.3 8.2 5.9 6.8 8.3 12.6 10.6 0.4 4.5 4.5
CNM (Queretaro) -9.2 -6.1 -11.1 -1.6 1.9 4.7 0.6 2.5 11.2 11.5
CNMP (Panama) -8.8 -1.3 -14.5 -3.5 9.7 -4.1 -8.6 0.6 7.3 7.3
DFNT (Tunis) 26815.5 27012.7 27202.2 27409.8 27599.2 27778.7 27958.8 0.7 20.0 20.0
DLR (Oberpfaffenhofen) 103.0 109.1 98.9 97.2 88.3 78.2 65.3 0.7 3.2 3.2
DMDM (Belgrade) 1043.6 1095.2 1146.0 1196.8 1235.5 1301.9 1351.9 0.4 3.1 3.1
DTAG (Frankfurt/M) 27.1 24.8 16.7 11.5 12.1 10.0 -1.5 0.4 3.0 3.0
EIM (Thessaloniki) - - - - - - -
ESTC (Noordwijk) 1.7 1.2 0.6 -0.8 -0.5 -1.3 -2.6 0.4 3.0 3.0
HKO (Hong Kong) 286.0 286.4 287.7 288.5 286.7 292.9 296.7 0.4 7.7 7.7
ICE (San Jose) -2.0 -5.9 -6.6 -6.3 -20.7 -27.5 -42.6 5.0 20.0 20.7
IFAG (Wettzell) -965.3 -964.7 -976.3 -972.2 -982.0 -988.1 -977.4 1.0 6.1 6.2
IMBH (Sarajevo) 1.9 -3.4 5.7 0.5 0.3 -2.4 -1.2 0.4 7.2 7.2
INCP (Lima) 41.4 36.5 33.9 44.1 21.0 29.5 18.4 5.0 20.0 20.7
INM (Bogota D.C.) -5.3 -6.0 -11.5 -91.9 -8.4 -4.9 -17.2 2.0 20.0 20.1 (2)
INPL (Jerusalem) -65.3 -58.1 -54.0 -52.8 -53.3 -61.4 -63.3 0.4 7.2 7.2
INTI (Buenos Aires) - - - - - - -
INXE (Rio de Janeiro) -17.8 -14.4 -6.7 -12.4 -7.3 -16.7 -13.0 0.4 20.0 20.0
IT (Torino) 3.3 2.3 -0.4 -9.1 -11.9 -7.1 -4.4 0.5 1.7 1.7 (3)
JATC (Lintong) 1.6 0.9 -0.1 0.2 1.2 2.2 0.3 0.4 2.6 2.6
JV (Kjeller) -54.8 -59.0 -56.7 -54.5 -53.8 -55.8 -50.5 0.4 20.0 20.0
KEBS (Nairobi) - - - - - - -
KIM (Serpong-Tangerang) 453.6 476.8 511.0 521.2 521.4 525.0 522.3 2.0 20.0 20.1
KRIS (Daejeon) -1.3 0.1 0.9 1.6 2.9 3.5 4.8 0.4 3.0 3.0
KZ (Astana) -3.6 2.0 13.5 19.7 33.0 31.8 37.3 1.5 9.7 9.8
LT (Vilnius) 198.3 163.2 182.1 200.5 191.0 200.4 194.5 2.0 11.3 11.4
MASM (Bayanzurkh) -161.4 -170.1 -177.5 -190.7 -208.6 -212.0 -218.6 0.5 20.0 20.0
MBM (Podgorica) 63390.4 63712.3 64014.6 64343.2 64653.1 64961.2 65284.9 1.5 20.0 20.1
MIKE (Espoo) 0.4 0.2 -0.1 -0.3 0.3 -0.1 0.0 0.7 4.3 4.4
MKEH (Budapest) 2726.2 2528.3 2341.0 2139.2 1938.8 1746.4 1556.0 1.5 20.0 20.1
MSL (Lower Hutt) 364.7 334.3 343.3 333.1 302.4 308.6 311.2 1.5 20.0 20.1
MTC (Makkah) 1476.5 1490.7 1503.7 1518.4 1529.4 42.9 53.1 1.7 8.3 8.5 (4)
NAO (Mizusawa) 115.0 111.2 106.2 88.6 90.9 82.1 71.6 2.0 20.0 20.1
NICT (Tokyo) 14.3 12.6 11.8 10.2 7.6 5.2 4.0 0.4 2.4 2.4
NIM (Beijing) -0.4 -0.5 -0.3 1.6 -0.5 0.2 0.3 0.4 2.3 2.3
NIMB (Bucharest) 1445.4 1500.8 1550.5 1595.4 1642.8 1699.3 1745.4 0.4 7.4 7.4
NIMT (Pathumthani) 55.3 38.9 31.5 22.9 15.3 -4.3 -23.4 1.5 3.4 3.8
NIS (Cairo) -23.6 -20.4 -18.1 -11.7 -7.9 -1.7 41.2 1.6 20.0 20.1
NIST (Boulder) -1.8 -2.6 -2.8 -2.9 -2.2 -0.7 0.4 0.4 2.0 2.1
NMIJ (Tsukuba) 10.3 11.3 10.8 10.6 11.8 11.9 11.4 0.4 3.2 3.2
NMLS (Sepang) -642.3 -681.6 -717.3 -751.4 -791.6 -832.4 -871.3 1.5 3.4 3.8
NPL (Teddington) 0.0 -1.1 -3.9 -4.2 -3.2 -2.3 -2.6 0.4 2.9 2.9
NPLI (New-Delhi) 4.6 11.6 11.7 16.4 17.6 18.0 16.3 2.0 19.9 20.0
NRC (Ottawa) 64.7 66.7 70.8 67.5 60.7 68.9 66.2 0.4 3.0 3.1
NRL (Washington DC) - - - - - - -
NTSC (Lintong) 2.9 1.7 0.5 2.0 2.7 3.0 0.8 0.4 2.4 2.4
ONBA (Buenos Aires) -2199.0 -2210.0 -2208.3 -2208.6 -2185.8 -2205.3 -2212.3 2.0 11.3 11.4
ONRJ (Rio de Janeiro) 1.4 -3.5 -5.9 -2.0 -1.8 1.8 1.0 1.0 7.9 7.9
OP (Paris) 1.4 0.7 0.2 1.2 1.0 -0.1 -1.7 0.4 1.6 1.7
ORB (Bruxelles) 2.9 2.5 0.3 0.9 1.7 1.4 1.6 0.4 3.0 3.0
PL (Warszawa) -18.5 -22.7 -14.1 -17.6 -15.9 -4.4 8.3 0.4 3.9 3.9
PTB (Braunschweig) 1.5 2.0 2.3 3.2 3.1 2.7 2.6 0.2 1.3 1.3
ROA (San Fernando) 0.2 1.3 2.2 3.1 3.0 0.3 -1.5 0.4 1.7 1.7
SASO (Riyadh) -748.4 -756.2 -763.0 - - - - 0.7 7.7 7.7
SCL (Hong Kong) -7.5 -2.1 3.8 10.2 5.4 - - 5.0 14.2 15.0
SG (Singapore) 29.7 25.8 19.0 11.1 4.6 -3.7 -8.9 0.4 6.5 6.5
SIQ (Ljubljana) 397.1 407.2 405.5 433.8 444.6 432.1 449.4 0.4 7.5 7.5
SMD (Bruxelles) -24.9 -20.6 -14.8 -3.4 -2.2 -7.8 1.0 0.4 3.0 3.0
SMU (Bratislava) -1637.3 -1639.2 -1642.8 -1647.8 -1662.3 -1652.9 -1665.5 1.5 12.3 12.4
SP (Boras) 4.8 4.9 4.8 4.6 4.5 4.1 3.7 0.4 1.6 1.7
SU (Moskva) -0.2 -0.3 0.3 0.4 0.5 0.6 0.6 1.3 6.8 6.9
TL (Chung-Li) -4.6 -4.6 -4.3 -4.6 -3.3 -1.9 -0.5 0.4 2.4 2.4
TP (Praha) -29.3 -20.1 -13.3 -8.5 -4.2 2.9 3.8 0.4 6.6 6.6
UA (Kharkov) -0.6 -2.1 -9.1 0.1 -1.7 -2.8 2.7 1.5 9.0 9.1
UAE (Abu Dhabi) - - - - - - -
UME (Gebze-Kocaeli) -142.5 -149.4 -154.1 -174.5 -169.5 -172.3 -219.4 0.7 3.2 3.2
USNO (Washington DC) 0.3 0.4 1.5 2.1 1.9 1.8 1.5 0.3 1.5 1.5
VMI (Ha Noi) -35.7 -24.3 -24.5 -21.5 -9.8 6.2 11.7 3.0 3.4 4.6
VSL (Delft) 10.6 13.4 14.7 -3.4 -10.0 -9.7 -4.2 0.4 1.7 1.8
ZA (Pretoria) 0.1 7.3 12.5 15.9 18.1 17.8 15.6 0.4 4.3 4.4
- Note on section 1:
(1) BOM : Apparent time step of UTC(BOM) of about +140 ns between MJD 58190 and 58193
(2) INM : Time step of about -100 ns on MJD 58190
(3) IT : Time step of +8 ns on MJD 58187
(4) MTC : Time step of +1500 ns on MJD 58195.76

2 - Difference between the normalized frequencies of EAL and TAI.
Interval of validity f(EAL)-f(TAI)
Steering correction 58174 - 58204 6.501x10-13 (2018 FEB 25 - 2018 MAR 27)
New correction 58204 - 58234 6.501x10-13 (2018 MAR 27 - 2018 APR 26)
New correction foreseen 58234 - 58269 6.501x10-13 (2018 APR 26 - 2018 MAY 31)

3 - Duration of the TAI scale interval d.

Table 1: Estimate of d by individual PSFS measurements and corresponding uncertainties.
All values are expressed in 10-15 and are valid only for the stated period of estimation.
Standard Period of d uA uB ul/lab ul/Tai u uSrep Ref(uS) Ref(uB) uB(Ref) Steer Note
Estimation
PTB-CS1 58174 58204 -20.98 8.00 8.00 0.00 0.13 11.31 PFS/NA T148 8. Y (1)
PTB-CS2 58174 58204 -3.54 5.00 12.00 0.00 0.13 13.00 PFS/NA T148 12. Y (1)
PTB-CSF1 58174 58204 0.02 0.07 0.37 0.10 0.13 0.41 PFS/NA T162 1.40 Y (2)
PTB-CSF2 58174 58204 -0.27 0.10 0.20 0.06 0.13 0.27 PFS/NA T287 0.41 Y (2)
SU-CsFO2 58174 58204 -1.09 0.29 0.24 0.13 0.85 0.94 PFS/NA T315 0.50 Y (3)
SYRTE-FORb 58174 58189 0.03 0.50 0.30 0.12 0.49 0.77 0.7 [1] T328 0.34 Y (4)

Notes:
(1) Continuously operating as a clock participating to TAI
(2) Report 27 MAR. 2018 by PTB
(3) Report 03 APR. 2018 by SU
(4) Report 04 APR. 2018 by LNE-SYRTE
[1] CIPM Recommendation 2 (CI-2015) : Updates to the list of standard frequencies in Proces-Verbaux
des Seances du Comite International des Poids et Mesures, 104th meeting (2015), 2016, 47 p.

Table 2: Estimate of d by the BIPM based on all PSFS measurements identified to be used for TAI steering
over the period MJD57814-58204, and corresponding uncertainties.

Period of estimation d u
58174-58204 -0.22x10-15 0.20x10-15 (2018 FEB 25 - 2018 MAR 27)

4 - Relations of UTC and TAI with predictions of UTC(k) disseminated by GNSS.

[UTC-UTC(USNO)_GPS] = C0', [TAI-UTC(USNO)_GPS] = 37 s + C0'
[UTC-UTC(SU)_GLONASS]= C1', [TAI-UTC(SU)_GLONASS]= 37 s + C1'

For this edition of Circular T, σ0'= 1.0 ns, σ1'= 6.6 ns

2018 0h UTC MJD C0'/ns N0 C1'/ns N1'
FEB 25 58174 -4.6 89 5.5 88
FEB 26 58175 -3.9 89 4.4 89
FEB 27 58176 -4.9 90 4.6 90
FEB 28 58177 -3.8 89 5.0 88
MAR 1 58178 -3.5 89 4.6 88
MAR 2 58179 -3.5 89 5.0 86
MAR 3 58180 -2.9 90 5.9 89
MAR 4 58181 -3.0 89 8.1 86
MAR 5 58182 -2.8 89 8.8 89
MAR 6 58183 -1.1 89 7.9 88
MAR 7 58184 -1.2 90 9.4 82
MAR 8 58185 -2.0 89 11.6 89
MAR 9 58186 -1.7 89 12.1 86
MAR 10 58187 0.4 89 10.9 65
MAR 11 58188 -0.2 90 8.7 65
MAR 12 58189 -0.4 89 8.9 84
MAR 13 58190 -0.3 89 9.1 85
MAR 14 58191 -1.3 89 10.5 89
MAR 15 58192 -1.2 90 8.2 79
MAR 16 58193 -1.1 89 4.9 53
MAR 17 58194 -1.3 89 6.6 86
MAR 18 58195 -1.7 89 8.9 83
MAR 19 58196 -2.9 90 8.4 88
MAR 20 58197 -2.7 89 6.7 85
MAR 21 58198 -1.2 89 7.4 85
MAR 22 58199 -3.1 89 8.6 89
MAR 23 58200 -1.7 90 8.7 90
MAR 24 58201 -1.8 89 8.8 88
MAR 25 58202 -1.2 89 9.2 84
MAR 26 58203 -1.5 89 8.1 78
MAR 27 58204 -1.4 90 6.5 86

5 - Time links used for the computation of TAI, calibrations information and corresponding uncertainties.

Link Type Equipment Cal_ID1 / Cal_ID2 uStb/ns uCal/ns uAg/ns Al/ns YYMM
APL /PTB GPS MC AP02 /PT10 NA_Al / 1001-2016 2.0 11.2 10.0
AUS /PTB GPSPPP AU01 /PT02 1002-2010 / 1001-2016 0.3 6.2 3.7
BEV /PTB GPSPPP BE1_ /PT02 1012-2016 / 1001-2016 0.3 2.8 1.3
BIM /PTB NL
BIRM/PTB GPSPPP BI01 /PT02 1015-2016 / 1001-2016 0.4 2.7 1.1
BOM /PTB GPS MC MABM /PT10 2004-2014 / 1001-2016 1.5 8.0 3.8
BY /PTB GPS MC BY46 /PT10 NA / 1001-2016 1.5 9.6 6.6
CAO /PTB NL
CNES/PTB GPSPPP CS21 /PT02 1101-2016 / 1001-2016 0.3 4.3 1.4
CNM /PTB GPS MC CN00 /PT10 NA_Al / 1001-2016 2.5 11.2 10.0 -27.3 0804
CNMP/PTB GPSPPP MP1_ /PT02 NA_Al / 1001-2016 0.5 7.2 1.7 41.7 1607
DFNT/PTB GPS P3 DN__ /PT02 NC_Al / 1001-2016 0.7 20.0 10.3 1507
DLR /PTB GPS P3 DL05 /PT02 1012-2016 / 1001-2016 0.7 2.9 1.4
DMDM/PTB GPSPPP ZM68 /PT02 1011-2016 / 1001-2016 0.3 2.8 1.3
DTAG/PTB GPSPPP DT04 /PT02 1015-2017 / 1001-2016 0.3 2.7 1.1
EIM /PTB NL
ESTC/PTB GPSPPP ES04 /PT02 1019-2016 / 1001-2016 0.3 2.7 1.1
HKO /PTB GPSPPP HKO2 /PT02 2002-2012 / 1001-2016 0.3 7.6 3.0
ICE /PTB GPS MC CE1_ /PT10 NC / 1001-2016 5.0 20.0
IFAG/PTB GPS P3 IF19 /PT02 NA_Al / 1001-2016 1.0 6.0 3.4
IMBH/PTB GPSPPP BH01 /PT02 2004-2016 / 1001-2016 0.3 7.1 1.0
INCP/PTB GPS MC CP__ /PT10 NC / 1001-2016 5.0 20.0
INM /PTB GPS MC IC__ /PT10 NC / 1001-2016 2.0 20.0
INPL/PTB GPSPPP IL05 /PT02 2002-2016 / 1001-2016 0.3 7.1 1.2
INTI/PTB NL
INXE/PTB GPSPPP NXRA /PT02 NC / 1001-2016 0.3 20.0
JV /PTB GPSPPP JV01 /PT02 NC_Al / 1001-2016 0.3 20.0 130.0 1509
KEBS/PTB NL
KIM /PTB GPS MC KI02 /PT10 NC_Al / 1001-2016 2.0 20.0 -30.6 0901
KRIS/PTB GPSPPP KRG1 /PT02 1017-2017 / 1001-2016 0.3 2.7 1.1
KZ /PTB GPS MC KZ01 /PT10 2002-2008 / 1001-2016 1.5 9.6 6.6
LT /PTB GPS MC LT01 /PT10 1007-2006 / 1001-2016 2.0 11.2 10.0
MASM/PTB GPSPPP MN__ /PT02 NC / 1001-2016 0.4 20.0
MBM /PTB GPS MC MEBM /PT10 NC / 1001-2016 1.5 20.0
MIKE/PTB GPS P3 MI04 /PT02 1102-2015 / 1001-2016 0.7 4.3 1.7
MKEH/PTB GPS MC MK01 /PT10 NC / 1001-2016 1.5 20.0
MSL /PTB GPS P3 MS0_ /PT02 NC / 1001-2016 1.5 20.0
MTC /PTB GPS MC MC02 /PT02 2001-2013 / 1001-2016 1.7 8.2 4.2
NAO /PTB GPS MC NAT2 /PT10 NC / 1001-2016 2.0 20.0
NICT/PTB GPSPPP NC01 /PT02 1001-2016 / 1001-2016 0.3 2.2 1.4
NIM /PTB GPSPPP IM06 /PT02 1001-2016 / 1001-2016 0.3 2.0 1.3
NIMB/PTB GPSPPP MB02 /PT02 NA_Al / 1001-2016 0.3 7.3 2.0 32.2 1611
NIMT/PTB GPS MC MTTO /PT10 1013-2017 / 1001-2016 1.5 3.2 1.9
NIS /PTB GPS P3 IS__ /PT02 NC_Al / 1001-2016 1.6 20.0 +16.4 1303
NMIJ/PTB GPSPPP NM0D /PT02 NA_Al / 1001-2016 0.3 3.0 2.4
NMLS/PTB GPS MC LSM1 /PT10 1013-2017 / 1001-2016 1.5 3.2 1.9
NPL /PTB GPSPPP NPL2 /PT02 1014-2017 / 1001-2016 0.3 2.7 1.1
NPLI/PTB GPS MC LIT4 /PT10 NC / 1001-2016 2.0 20.0
NRC /PTB GPSPPP NRC4 /PT02 1017-2016 / 1001-2016 0.3 2.8 1.2
NRL /PTB NL
NTSC/PTB GPSPPP NTP3 /PT02 1001-2016 / 1001-2016 0.3 2.1 1.2
ONBA/PTB GPS MC ON__ /PT10 1002-2004 / 1001-2016 2.0 11.2 10.0
ONRJ/PTB GPS P3 RJ01 /PT02 NA_Al / 1001-2016 1.0 7.8 3.3 +5.6 1302
ORB /PTB GPSPPP OR1Z /PT02 1018-2017 / 1001-2016 0.3 2.7 1.1
PL /PTB GPSPPP PL_3 /PT02 1101-2013 / 1001-2016 0.3 3.7 2.8
SASO/PTB GPS P3 SA00 /PT02 NA_Al / 1001-2016 0.7 7.6 3.0 32.8 1312
SCL /PTB GPS MC SC__ /PT10 1001-1993 / 1001-2016 5.0 14.1 10.0
SG /PTB GPSPPP SG01 /PT02 NA_Al / 1001-2016 0.3 6.4 3.9 -114.2 1802
SIQ /PTB GPSPPP SI01 /PT02 2002-2014 / 1001-2016 0.3 7.4 2.3
SMD /PTB GPSPPP SD21 /PT02 1014-2017 / 1001-2016 0.3 2.7 1.1
SMU /PTB GPS MC SM00 /PT10 NA_Al / 1001-2016 1.5 12.2 10.0 57.8 0908
SU /PTB GPS MC SU19 /PT10 NA_Al / 1001-2016 1.5 7.9 6.2 -7.8 1411
TL /PTB GPSPPP TLT1 /PT02 1001-2016 / 1001-2016 0.3 2.1 1.5
TP /PTB GPSPPP TP04 /PT02 1002-2009 / 1001-2016 0.3 6.5 4.2
UA /PTB GPS MC UA04 /PT10 2003-2011 / 1001-2016 1.5 8.9 5.4
UAE /PTB NL
UME /PTB GPS P3 UM01 /PT02 1011-2016 / 1001-2016 0.7 2.9 1.4
VMI /PTB GPS MC VM__ /PT10 1013-2017 / 1001-2016 3.0 3.2 1.9
ZA /PTB GPSPPP ZA02 /PT02 1102-2016 / 1001-2016 0.3 4.2 1.2
Link Type Equipment Cal_ID uStb/ns uCal/ns uAg/ns Al/ns YYMM
AOS /PTB TWGPPP AOS01 /PTB05 0449-2017 0.4 3.0 1.2
CH /PTB TWGPPP CH01 /PTB05 0284-2012 0.3 1.7 1.4
IT /PTB TWSTFT IT02 /PTB05 0434-2016 0.5 1.1 0.5
JATC/NTSC INT LK INTDLY 3001-2017 0.2 1.1 0.4
NIST/PTB TWGPPP NIST01/PTB05 0393-2015 0.3 1.7 0.8
OP /PTB TWGPPP OP01 /PTB05 0437-2016 0.3 1.1 0.5
ROA /PTB TWGPPP ROA01 /PTB05 0440-2016 0.3 1.1 0.5
SP /PTB TWGPPP SP01 /PTB05 0441-2016 0.3 1.1 0.5
USNO/PTB TWGPPP USNO01/PTB05 0395-2016 0.3 1.1 0.3
VSL /PTB TWGPPP VSL01 /PTB05 0295-2015 0.3 1.2 0.6