CIRCULAR T 461

ISSN 1143-1393
2026 JUNE 11, 14h 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_v0.8.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 2026 0h UTC APR 29 MAY 4 MAY 9 MAY 14 MAY 19 MAY 24 MAY 29 Uncertainty/ns Notes
MJD 61159 61164 61169 61174 61179 61184 61189 uA uB u
Laboratory k [UTC-UTC(k)]/ns
AGGO (La Plata) 306.8 304.2 298.3 297.4 301.7 302.4 298.1 0.7 3.2 3.3
AOS (Borowiec) 5.5 5.8 5.9 5.8 5.2 5.3 4.4 0.2 2.7 2.7
APL (Laurel) 1.0 0.4 -0.3 -1.1 -0.4 0.8 2.4 0.2 NC -
AUS (Sydney) -10.5 -1.4 15.2 36.9 21.8 9.7 22.2 0.2 3.2 3.2
AZ (Baku) 865.8 883.5 896.0 914.5 926.2 938.8 959.2 0.2 7.1 7.1
BEV (Wien) 15.6 16.7 6.3 22.3 34.4 19.7 -0.7 0.2 3.2 3.2
BFKH (Budapest) 5653.5 5700.6 5745.4 5776.6 5816.4 5860.0 5907.9 1.5 7.3 7.4
BIM (Sofiya) 7290.0 7337.6 7377.4 7418.6 7468.6 7510.8 7555.7 0.2 2.9 2.9
BIRM (Beijing) 0.2 -0.7 -0.2 0.4 1.7 -0.2 -0.1 0.2 3.7 3.7
BSJ (Kingston) 1.8 0.6 12.9 4.5 6.1 7.6 10.1 1.5 7.4 7.5
BY (Minsk) 8.3 11.8 10.8 9.1 - -1.4 -5.2 1.5 3.3 3.6
CAO (Cagliari) 144.5 140.6 139.6 140.7 139.6 143.7 139.9 0.7 NC -
CH (Bern-Wabern) -0.6 -0.7 -1.0 -1.2 -1.3 -1.4 -1.2 0.2 1.2 1.2
CNES (Toulouse) -1.4 1.1 1.7 -2.1 -2.1 -1.3 -0.3 0.2 2.6 2.6
CNM (Queretaro) 4.4 1.2 -1.1 0.0 0.7 0.4 -0.5 3.0 4.6 5.5
CNMP (Panama) -12.0 -0.8 5.4 0.1 1.3 -3.0 -1.5 0.2 5.7 5.7
DFM (Horsholm) 1.1 0.5 0.8 0.7 -0.8 -0.8 -0.1 0.2 3.0 3.0
DFNT (Tunis) -1591.4 -1669.3 -1752.4 -1843.5 -1916.7 -2004.6 -2082.2 0.7 2.7 2.8
DLR (Oberpfaffenhofen) -0.5 -0.9 -2.1 -2.7 -2.9 -1.7 -0.8 0.7 2.6 2.7
DMDM (Belgrade) -2.1 0.9 -3.0 -1.5 -6.7 -16.4 -13.3 0.2 7.5 7.5
DTAG (Frankfurt/M) -29.2 -43.7 -37.4 -34.2 -33.4 -28.4 -18.7 0.2 2.6 2.6
ESA (Noordwijk) 0.5 1.1 0.9 -0.7 -0.0 -2.1 -1.6 0.2 2.6 2.6
HKO (Hong Kong) 1225.6 1238.2 1256.7 1285.6 1305.4 1319.8 1344.7 0.2 3.9 3.9
IBM (La Paz) -66.2 -73.7 -83.3 -99.1 -111.4 -111.5 -119.9 4.0 7.7 8.7
ICE (San Jose) 11.0 4.6 12.0 15.6 13.2 4.9 -15.8 0.7 7.2 7.2
IDN (Serpong-Tangerang) 8503.5 8659.3 8815.2 8972.0 9109.4 9262.1 9411.5 0.2 NC -
IFAG (Wettzell) -1023.5 -1005.4 -992.6 -971.7 -953.8 -945.6 -923.0 0.2 2.6 2.6
IFZG (Zagreb) 313.4 318.2 326.8 329.5 333.4 333.2 320.2 0.2 2.9 2.9
IMBH (Sarajevo) 3.3 0.5 -0.0 0.1 0.4 1.5 -1.0 0.2 3.1 3.1
INCP (Lima) -17.4 -16.4 -27.0 -44.1 -40.6 -54.1 -43.6 5.0 4.0 6.4
INM (Bogota D.C.) -35.4 -33.5 -31.6 -15.5 -13.3 -7.2 -1.2 3.0 3.9 4.9
INPL (Jerusalem) -116.5 -118.6 -116.7 -121.1 -121.9 -134.8 -148.7 0.2 7.7 7.7
INTI (Buenos Aires) -168.0 -163.2 -161.0 -154.9 -161.2 -154.4 -144.6 0.2 3.4 3.4
INXE (Rio de Janeiro) -2.4 - 0.8 18.7 3.9 56.0 8.5 0.7 3.5 3.6
IPQ (Caparica) -675.7 -703.0 -772.6 -843.9 -922.8 - -690.6 0.7 3.2 3.3
IT (Torino) 0.4 -0.2 -0.6 -0.6 -0.5 -0.4 -0.3 0.2 1.2 1.2
JATC (Lintong) -0.3 -0.6 -0.6 -0.7 -0.4 -0.2 0.1 0.2 3.9 3.9
JV (Kjeller) 1.2 3.1 4.4 4.5 3.4 1.8 0.2 0.2 5.0 5.0
KRIS (Daejeon) -0.1 -0.6 -1.4 -2.2 -2.4 -1.9 -1.5 0.2 3.2 3.2
KZ (Astana) -2.0 -2.2 -2.6 -2.9 -2.0 5.8 4.4 0.7 4.4 4.5
LRTE (Sao Carlos) -0.6 0.3 1.1 -3.8 -0.8 1.1 -2.2 0.2 3.6 3.6
LT (Vilnius) 1459.1 1465.8 1474.6 1479.8 1486.4 1485.0 1487.8 0.2 2.8 2.8
LUX (Belvaux) -4.2 -11.1 -13.1 -15.9 -20.5 -12.9 -8.5 0.5 2.6 2.6
MBM (Podgorica) 4702.7 4736.0 4742.6 4773.2 4793.0 4802.3 4809.0 0.2 3.1 3.1
MIKE (Espoo) 4.2 5.8 4.4 4.6 4.9 5.6 6.5 0.2 2.8 2.8
MSL (Lower Hutt) -22.6 -6.4 -2.0 3.2 -3.3 10.3 19.5 0.7 3.2 3.3
MTC (Makkah) 143.6 157.7 163.5 178.5 196.6 207.0 224.2 1.0 74.7 74.7
NAO (Mizusawa) -129.5 -143.8 -141.9 -140.9 -127.9 -108.6 -92.9 2.0 3.9 4.4
NICT (Tokyo) 1.1 0.9 1.1 1.1 1.0 0.4 0.3 0.2 2.2 2.2
NIM (Beijing) 0.3 0.1 0.3 0.2 -0.1 -0.1 -0.1 0.2 2.2 2.2
NIMB (Bucharest) 1980.5 1987.3 1985.6 1994.0 2001.1 2008.3 2013.8 0.7 7.0 7.0
NIMT (Pathumthani) 4.7 4.1 4.1 5.7 -4.4 -7.1 -4.7 0.7 2.5 2.6
NIS (Cairo) -31.4 -31.3 -22.3 -15.3 -11.0 -2.3 5.4 0.7 7.3 7.3
NIST (Boulder) 1.0 0.8 0.9 0.5 0.2 -0.1 -0.3 0.2 2.0 2.0
NMIJ (Tsukuba) 6.1 6.1 5.7 5.6 6.4 7.5 9.0 0.2 3.1 3.1
NMLS (Sepang) -266.8 -266.8 -270.5 -269.2 -263.9 -268.1 -272.3 0.2 2.9 2.9
NPL (Teddington) -1.2 -2.9 -2.6 -3.5 -1.3 -2.6 -2.9 0.2 1.2 1.2
NPLI (New-Delhi) -4.0 -3.9 -3.6 -3.1 -2.3 -1.7 -1.3 0.2 2.7 2.7
NRC (Ottawa) 0.8 0.8 0.8 0.8 0.8 0.9 1.8 0.2 2.8 2.8
NRL (Washington DC) - - - - - - -
NSAI (Dublin) - - - - - - -
NTSC (Lintong) -0.1 -0.3 -0.2 -0.5 -0.3 0.1 0.2 0.2 3.8 3.8
ONBA (Buenos Aires) 3719.3 3750.5 3777.0 3808.7 3829.2 3853.2 3873.2 2.0 3.5 4.0
ONRJ (Rio de Janeiro) -1.5 0.7 -1.6 -1.0 1.3 -1.1 -1.6 0.2 3.4 3.4
OP (Paris) 0.3 0.4 0.6 0.5 0.6 0.6 0.8 0.2 1.2 1.2
ORB (Bruxelles) -0.7 -0.9 -0.5 0.4 1.1 1.3 1.2 0.2 2.9 2.9
PL (Warszawa) -6.4 - -6.0 -6.0 -5.7 -5.4 -5.3 0.2 2.7 2.7
PTB (Braunschweig) 0.1 0.0 -0.1 -0.2 -0.2 -0.1 -0.1 0.2 1.2 1.2
ROA (San Fernando) 1.3 1.3 3.4 2.7 1.2 0.0 -0.8 0.2 1.2 1.2
SASO (Riyadh) 828.8 830.2 827.3 823.3 827.1 820.2 820.3 0.5 3.9 3.9
SCL (Hong Kong) 2.4 6.3 -0.0 4.1 11.2 0.4 -4.8 0.2 3.9 3.9
SG (Singapore) -4.3 -3.1 1.0 -5.0 3.9 15.4 -12.0 0.2 2.8 2.8
SIQ (Ljubljana) 1525.5 1520.4 1523.6 1523.0 1528.0 1533.0 1521.1 0.2 4.3 4.3
SMD (Bruxelles) 0.7 1.0 1.1 1.0 1.0 0.4 0.2 0.2 4.6 4.6
SMU (Bratislava) 119.2 120.9 52.1 96.3 114.4 32.0 -8.8 1.5 6.2 6.4
SP (Boras) 1.2 1.4 1.7 2.0 2.2 2.3 2.1 0.2 1.2 1.2
SU (Moskva) 0.9 1.0 0.9 1.0 1.0 0.9 1.0 0.2 3.0 3.0
TL (Chung-Li) 1.0 0.8 -0.2 -1.0 -1.1 -1.0 -1.2 0.2 2.1 2.1
TP (Praha) -14.4 -12.0 2.9 3.7 12.3 9.7 14.5 0.2 3.2 3.2
UA (Kharkiv) -9.6 - 2.6 -9.4 -0.9 0.1 -10.3 3.0 7.6 8.2
UAE (Abu Dhabi) -5.3 -1.5 -2.0 -4.9 -4.3 -12.8 -16.0 0.7 7.0 7.0
UME (Gebze-Kocaeli) -3.2 -1.3 2.3 7.2 7.6 -2.2 -11.8 0.2 22.5 22.5
USNO (Washington DC) 1.1 1.3 1.7 2.2 1.5 0.9 0.7 0.2 2.4 2.4
UZ (Tashkent) 65.3 54.2 47.5 43.1 39.0 34.7 28.3 0.2 2.5 2.5
VMI (Ha Noi) 292.1 279.2 345.2 408.1 468.4 - 89.4 0.7 3.1 3.2
VSL (Delft) 0.4 0.8 0.1 -2.1 -4.5 -2.5 0.6 0.2 1.3 1.3
ZA (Pretoria) -2.3 6.4 11.9 16.2 18.4 16.9 14.9 14.9 3.8 15.4

2 - Difference between the normalized frequencies of EAL and TAI.
Interval of validity f(EAL)-f(TAI)
Steering correction 61159 - 61189 6.498x10-13 (2026 APR 29 - 2026 MAY 29)
New correction 61189 - 61219 6.498x10-13 (2026 MAY 29 - 2026 JUN 28)
New correction foreseen 61219 - 61249 6.499x10-13 (2026 JUN 28 - 2026 JUL 28)

3 - Duration of the TAI scale interval d.

Table 1: Estimate of d by individual PSFS measurements and corresponding uncertainty.
All values are expressed in 10-15 and are valid only for the stated period of estimation.
Standard Period of d uA uB uA/Lab uB/Lab ul/Tai u uSrep Ref(uS) Ref(uB) uB(Ref) Uptime LastRep Nrep3y Steer Note
Estimation %
PTB-CS1 61159 61189 -19.40 8.00 8.00 0.00 0.00 0.13 11.31 PFS/NA T148 8.00 100.0 T460 36 Y (1)
PTB-CS2 61159 61189 -19.79 5.00 12.00 0.00 0.00 0.13 13.00 PFS/NA T148 12.00 100.0 T460 36 Y (1)
MIKES-Sr+1 61159 61174 -0.24 0.00 0.00 0.04 0.02 0.24 0.25 0.17 [1] T457 0.00 97.9 T460 13 Y (2)
MIKES-Sr+1 61184 61189 -0.46 0.00 0.00 0.14 0.02 0.65 0.67 0.17 [1] T457 0.00 93.1 T460 13 Y (2)
NICT-Sr1 61159 61189 -0.08 0.03 0.06 0.20 0.06 0.13 0.26 0.17 [1] T371 0.06 2.1 T460 3 Y (3)
NIM5 61159 61189 0.06 0.49 0.68 0.10 0.01 0.13 0.85 PFS/NA T340 1.40 93.0 T460 26 Y (4)
NIM6 61159 61189 -0.14 0.17 0.20 0.10 0.01 0.13 0.31 PFS/NA [2] 0.22 96.7 T460 19 Y (4)
NIST-F4 61159 61174 -0.45 0.36 0.22 0.10 0.01 0.24 0.50 PFS/NA T452 0.22 95.0 T460 15 Y (5)
NRC-FCs2 61159 61189 0.04 0.12 0.12 0.11 0.00 0.13 0.24 PFS/NA T448 0.11 94.9 T460 37 Y (6)
NTSC-CsF2 61159 61189 -0.55 0.45 0.34 0.10 0.00 0.13 0.59 PFS/NA T435 0.43 92.1 T460 43 Y (7)
NTSC-Sr2 61159 61189 -0.32 0.00 0.05 0.35 0.02 0.13 0.38 0.17 [1] T457 0.00 18.0 T458 11 Y (8)
LNEOP-FO2 61159 61189 -0.37 0.20 0.21 0.09 0.00 0.13 0.33 PFS/NA T301 0.23 80.4 T460 32 Y (9)
LNEOP-FORb 61159 61189 0.06 0.30 0.24 0.09 0.00 0.13 0.42 0.34 [1] T328 0.34 79.7 T460 32 Y (9)
PTB-CSF2 61159 61189 -0.37 0.12 0.17 0.02 0.00 0.13 0.25 PFS/NA T370 0.17 93.4 T460 39 Y (10)
PTB-Yb1E3 59634 59669 -0.14 0.00 0.00 0.03 0.01 0.06 0.07 0.17 [1] T461 0.00 85.6 N/A 0 Y (10)
PTB-Yb1E3 59669 59699 0.06 0.00 0.00 0.07 0.01 0.07 0.10 0.17 [1] T461 0.00 67.4 N/A 0 Y (10)
PTB-Yb1E3 59699 59729 0.30 0.00 0.00 0.12 0.01 0.07 0.14 0.17 [1] T461 0.00 49.3 N/A 0 Y (10)
PTB-Yb1E3 59729 59759 0.20 0.00 0.00 0.05 0.01 0.07 0.08 0.17 [1] T461 0.00 73.8 N/A 0 Y (10)
PTB-Yb1E3 59759 59789 0.15 0.00 0.00 0.01 0.01 0.07 0.07 0.17 [1] T461 0.00 97.1 N/A 0 Y (10)
PTB-Yb1E3 59789 59819 0.24 0.00 0.00 0.06 0.01 0.07 0.09 0.17 [1] T461 0.00 75.7 N/A 0 Y (10)
PTB-Yb1E3 59819 59849 0.46 0.00 0.00 0.09 0.01 0.07 0.11 0.17 [1] T461 0.00 65.7 N/A 0 Y (10)
PTB-Yb1E3 59849 59879 0.37 0.00 0.00 0.07 0.01 0.07 0.10 0.17 [1] T461 0.00 70.6 N/A 0 Y (10)
PTB-Yb1E3 59879 59909 0.15 0.00 0.00 0.10 0.01 0.07 0.12 0.17 [1] T461 0.00 66.8 N/A 0 Y (10)
PTB-Yb1E3 59909 59944 -0.26 0.00 0.00 0.18 0.01 0.06 0.19 0.17 [1] T461 0.00 30.7 N/A 0 Y (10)
PTB-Yb1E3 59944 59974 0.04 0.00 0.00 0.05 0.01 0.10 0.12 0.17 [1] T461 0.00 79.3 N/A 0 Y (10)
PTB-Yb1E3 59974 59999 -0.01 0.00 0.00 0.03 0.01 0.12 0.13 0.17 [1] T461 0.00 85.1 N/A 0 Y (10)
PTB-Yb1E3 59999 60034 0.12 0.00 0.00 0.04 0.01 0.06 0.07 0.17 [1] T461 0.00 69.2 N/A 0 Y (10)
PTB-Yb1E3 60034 60064 0.30 0.00 0.00 0.02 0.01 0.07 0.07 0.17 [1] T461 0.00 84.2 N/A 0 Y (10)
PTB-Yb1E3 60064 60094 0.07 0.00 0.00 0.07 0.01 0.07 0.10 0.17 [1] T461 0.00 58.6 N/A 0 Y (10)
PTB-Yb1E3 60094 60124 0.23 0.00 0.00 0.20 0.01 0.07 0.21 0.17 [1] T461 0.00 29.0 N/A 0 Y (10)
PTB-Yb1E3 60124 60154 -0.29 0.00 0.00 0.10 0.01 0.07 0.12 0.17 [1] T461 0.00 50.4 N/A 0 Y (10)
PTB-Yb1E3 60154 60184 0.06 0.00 0.00 0.07 0.01 0.07 0.10 0.17 [1] T461 0.00 51.0 N/A 0 Y (10)
PTB-Yb1E3 60184 60214 -0.04 0.00 0.00 0.09 0.01 0.10 0.14 0.17 [1] T461 0.00 59.5 N/A 0 Y (10)
PTB-Yb1E3 60214 60244 -0.07 0.00 0.00 0.05 0.01 0.13 0.14 0.17 [1] T461 0.00 79.6 N/A 0 Y (10)
PTB-Yb1E3 60244 60274 0.06 0.00 0.00 0.22 0.01 0.10 0.24 0.17 [1] T461 0.00 18.4 N/A 0 Y (10)
PTB-Yb1E3 60274 60309 -0.49 0.00 0.00 0.12 0.01 0.06 0.13 0.17 [1] T461 0.00 50.0 N/A 0 Y (10)
PTB-Yb1E3 60309 60339 -0.05 0.00 0.00 0.13 0.01 0.07 0.15 0.17 [1] T461 0.00 37.0 N/A 0 Y (10)
PTB-Yb1E3 60339 60369 0.13 0.00 0.00 0.03 0.01 0.07 0.07 0.17 [1] T461 0.00 81.4 N/A 0 Y (10)
PTB-Yb1E3 60369 60399 0.22 0.00 0.00 0.05 0.01 0.07 0.08 0.17 [1] T461 0.00 75.4 N/A 0 Y (10)
PTB-Yb1E3 60399 60429 0.20 0.00 0.00 0.05 0.01 0.07 0.08 0.17 [1] T461 0.00 67.6 N/A 0 Y (10)
PTB-Yb1E3 60429 60459 0.21 0.00 0.00 0.08 0.01 0.10 0.13 0.17 [1] T461 0.00 40.4 N/A 0 Y (10)
PTB-Yb1E3 60459 60489 0.20 0.00 0.00 0.04 0.01 0.13 0.14 0.17 [1] T461 0.00 69.9 N/A 0 Y (10)
PTB-Yb1E3 60489 60519 0.22 0.00 0.00 0.07 0.01 0.13 0.15 0.17 [1] T461 0.00 74.4 N/A 0 Y (10)
PTB-Yb1E3 60519 60549 0.20 0.00 0.00 0.03 0.01 0.13 0.13 0.17 [1] T461 0.00 75.2 N/A 0 Y (10)
PTB-Yb1E3 60549 60579 0.29 0.00 0.00 0.05 0.01 0.13 0.14 0.17 [1] T461 0.00 66.0 N/A 0 Y (10)
PTB-Yb1E3 60579 60614 0.41 0.00 0.00 0.05 0.01 0.11 0.12 0.17 [1] T461 0.00 76.5 N/A 0 Y (10)
PTB-Yb1E3 60614 60644 0.41 0.00 0.00 0.06 0.01 0.13 0.14 0.17 [1] T461 0.00 69.5 N/A 0 Y (10)
PTB-Yb1E3 60644 60674 0.23 0.00 0.00 0.04 0.01 0.13 0.14 0.17 [1] T461 0.00 78.8 N/A 0 Y (10)
PTB-Yb1E3 60674 60704 0.20 0.00 0.00 0.04 0.01 0.13 0.14 0.17 [1] T461 0.00 79.6 N/A 0 Y (10)
PTB-Yb1E3 60704 60734 0.13 0.00 0.00 0.04 0.01 0.13 0.14 0.17 [1] T461 0.00 78.5 N/A 0 Y (10)
PTB-Yb1E3 60734 60764 0.08 0.00 0.00 0.03 0.01 0.13 0.13 0.17 [1] T461 0.00 82.4 N/A 0 Y (10)
PTB-Yb1E3 60764 60794 -0.04 0.00 0.00 0.02 0.01 0.13 0.13 0.17 [1] T461 0.00 89.6 N/A 0 Y (10)
PTB-Yb1E3 60794 60824 -0.01 0.00 0.00 0.03 0.01 0.13 0.13 0.17 [1] T461 0.00 83.8 N/A 0 Y (10)
PTB-Yb1E3 60824 60854 -0.04 0.00 0.00 0.02 0.01 0.13 0.13 0.17 [1] T461 0.00 85.8 N/A 0 Y (10)
PTB-Yb1E3 60854 60884 -0.00 0.00 0.00 0.02 0.01 0.13 0.13 0.17 [1] T461 0.00 84.2 N/A 0 Y (10)
PTB-Yb1E3 60884 60914 0.05 0.00 0.00 0.02 0.01 0.13 0.13 0.17 [1] T461 0.00 83.1 N/A 0 Y (10)
PTB-Yb1E3 60914 60944 0.07 0.00 0.00 0.08 0.01 0.13 0.15 0.17 [1] T461 0.00 66.4 N/A 0 Y (10)
PTB-Yb1E3 61159 61189 -0.30 0.00 0.00 0.05 0.01 0.13 0.14 0.17 [1] T461 0.00 73.9 N/A 0 Y (10)
SU-CsFO2 61159 61189 0.15 0.25 0.22 0.17 0.00 0.13 0.40 PFS/NA T315 0.50 83.1 T460 36 Y (11)

Notes:
(1) Continuously operating as a clock participating to TAI
(2) Report dated 29 MAY. 2026 by MIKES
(3) Report dated 02 JUN. 2026 by NICT
(4) Report dated 02 JUN. 2026 by NIM
(5) Report dated 01 JUN. 2026 by NIST
(6) Report dated 30 MAY. 2026 by NRC
(7) Report dated 03 JUN. 2026 by NTSC
(8) Report dated 09 JUN. 2026 by NTSC
(9) Report dated 04 JUN. 2026 by LNE-OP
(10) Report dated 03 JUN. 2026 by PTB
(11) Report dated 03 JUN. 2026 by SU
[1] CCTF Recommendation Redefinition (2025), 24th meeting (session II),
available at https://www.bipm.org/en/committees/cc/cctf/24-_2-2025
[2] Corrigendum: Uncertainty evaluation of the caesium fountain primary frequency standard NIM6 (2025 Metrologia 62 035005).
Zheng F., Chen W., Liu K., Dai S., Liu N., Wang Y. and Fang F., Metrologia 63 029501.

Table 2: Estimate of d by the BIPM based on all PSFS measurements identified to be used for TAI steering
over the period MJD 60799-61189, and corresponding uncertainties.

Period of estimation d u
61159-61189 -0.19x10-15 0.09x10-15 (2026 APR 29 - 2026 MAY 29)

4 - Relations of UTC with predictions of UTC broadcast by GNSS.

For this edition of Circular T:

σ_GPS = 5 ns
σ_GLO = 10 ns
σ_GAL = 5 ns
σ_BDS = 5 ns

DATE 0h UTC MJD UTC-bUTC_GNSS /ns
GPS GLO GAL BDS
2026-04-29 61159 1.2 -9.8 0.5 1.7
2026-04-30 61160 1.6 -9.5 0.5 1.7
2026-05-01 61161 -0.1 -13.2 -0.5 2.0
2026-05-02 61162 0.5 -13.8 -0.2 1.5
2026-05-03 61163 2.2 -14.0 -0.5 1.8
2026-05-04 61164 0.5 -16.6 -0.7 1.6
2026-05-05 61165 1.5 -1.3 -0.7 1.8
2026-05-06 61166 0.9 -5.0 -0.3 1.5
2026-05-07 61167 0.5 -8.7 1.7 1.6
2026-05-08 61168 0.5 -12.4 2.6 1.4
2026-05-09 61169 2.1 -8.4 3.7 1.9
2026-05-10 61170 2.8 -9.4 3.4 1.7
2026-05-11 61171 1.1 -14.9 3.7 1.4
2026-05-12 61172 0.4 -15.7 3.5 1.3
2026-05-13 61173 -0.1 -21.0 3.6 1.3
2026-05-14 61174 2.2 -20.6 3.4 1.0
2026-05-15 61175 1.2 -21.6 1.9 1.9
2026-05-16 61176 2.7 -19.5 3.0 1.0
2026-05-17 61177 2.4 -17.4 3.0 1.3
2026-05-18 61178 -0.6 -16.7 2.8 1.2
2026-05-19 61179 -0.1 -12.1 0.8 1.0
2026-05-20 61180 -0.8 -15.2 -1.0 1.4
2026-05-21 61181 1.2 -22.7 -0.2 1.1
2026-05-22 61182 0.3 -23.2 -0.3 1.2
2026-05-23 61183 0.1 -24.9 -0.4 1.1
2026-05-24 61184 -0.7 -27.3 -0.3 1.2
2026-05-25 61185 0.1 -29.2 -0.3 1.3
2026-05-26 61186 0.4 -31.5 -0.6 1.1
2026-05-27 61187 0.7 -28.4 -0.9 0.8
2026-05-28 61188 -0.5 -25.8 -1.0 1.0
2026-05-29 61189 0.3 -30.8 0.4 0.9

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
AGGO/PTB GPS P3 TC_2 /PT13 1014-2021 / 1001-2025 0.7 3.2 2.0
AOS /PTB GPSPPP AO_5 /PT13 1012-2024 / 1001-2025 0.3 2.7 1.1
APL /PTB GPSPPP AP04 /PT13 NC / 1001-2025 0.3 NC
AUS /PTB GPSPPP AU06 /PT13 1015-2021 / 1001-2025 0.3 3.2 2.0
AZ /PTB GPSPPP AZ01 /PT13 2002-2024 / 1001-2025 0.3 7.1 0.9
BEV /PTB GPSPPP BE1_ /PT13 1016-2021 / 1001-2025 0.3 3.2 2.0
BFKH/PTB GPS MC MK01 /PT13 NA_Al / 1001-2025 1.5 7.3 1.8 -193.2 2406
BIM /PTB GPSPPP BM51 /PT13 1016-2023 / 1001-2025 0.3 2.9 1.4
BIRM/PTB GPSPPP BI41 /PT13 1016-2018 / 1001-2025 0.3 3.7 2.7
BSJ /PTB GPS P3 JM__ /PT13 2001-2026 / 1001-2025 1.5 7.4 2.3
BY /PTB GPS MC BY46 /PT13 1020-2021 / 1001-2025 1.5 3.3 2.0
CAO /PTB GPS P3 CA__ /PT13 NC / 1001-2025 0.7 NC
CNES/PTB GPSPPP CS24 /PT13 1011-2025 / 1001-2025 0.3 2.6 0.5
CNM /PTB GPS MC CN00 /PT13 NA_Al / 1001-2025 3.0 4.6 3.2 -27.3 0804
CNMP/PTB GPSPPP MP1_ /PT13 1011-2017 / 1001-2025 0.3 5.7 3.2
DFM /PTB GPSPPP DK01 /PT13 1017-2022 / 1001-2025 0.3 3.0 1.6
DFNT/PTB GPS P3 DN__ /PT13 1015-2024 / 1001-2025 0.7 2.7 1.1
DLR /PTB GAL P3 DL11 /PT13 1016-2024 / 1001-2025 0.7 2.6 0.8
DMDM/PTB GPSPPP ZM01 /PT13 2002-2018 / 1001-2025 0.3 7.5 2.8
DTAG/PTB GPSPPP DT05 /PT13 1016-2024 / 1001-2025 0.3 2.6 0.7
ESA /PTB GPSPPP ES07 /PT13 1017-2024 / 1001-2025 0.3 2.6 0.9
HKO /PTB GPSPPP HKO1 /PT13 1011-2018 / 1001-2025 0.3 3.9 3.0
IBM /PTB GPS MC BO__ /PT13 2005-2016 / 1001-2025 4.0 7.7 3.3
ICE /PTB GPS P3 CE__ /PT13 2001-2023 / 1001-2025 0.7 7.2 1.5
IDN /PTB GPSPPP KI03 /PT13 NC / 1001-2025 0.3 NC
IFAG/PTB GPSPPP IF20 /PT13 1016-2024 / 1001-2025 0.3 2.6 0.8
IFZG/PTB GPSPPP HR01 /PT13 1016-2023 / 1001-2025 0.3 2.9 1.4
IMBH/PTB GPSPPP BH02 /PT13 1013-2022 / 1001-2025 0.3 3.1 1.8
INCP/PTB GPS MC CP__ /PT13 1012-2023 / 1001-2025 5.0 4.0 0.8
INM /PTB GPS MC IC__ /PT13 1012-2023 / 1001-2025 3.0 3.9 0.6
INPL/PTB GPSPPP IL06 /PT13 2003-2016 / 1001-2025 0.3 7.7 3.3
INTI/PTB GPSPPP INTI /PT13 1014-2021 / 1001-2025 0.3 3.4 1.8
INXE/PTB GPS P3 NXRA /PT13 1012-2020 / 1001-2025 0.7 3.5 2.5
IPQ /PTB GPS P3 IP05 /PT13 1017-2021 / 1001-2025 0.7 3.2 2.1
JATC/PTB GPSPPP JA02 /PT13 1201-2018 / 1001-2025 0.3 3.9 2.9
JV /PTB GPSPPP JV02 /PT13 1101-2017 / 1001-2025 0.3 5.0 3.0
KRIS/PTB GPSPPP KRP1 /PT13 1015-2021 / 1001-2025 0.3 3.2 2.0
KZ /PTB GPS P3 KZ04 /PT13 1202-2021 / 1001-2025 0.7 4.4 1.9
LRTE/PTB GPSPPP LRR2 /PT13 1201-2025 / 1001-2025 0.3 3.6 0.9
LT /PTB GPSPPP LT03 /PT13 1020-2023 / 1001-2025 0.3 2.8 1.2
LUX /PTB GPSPPP LU01 /PT13 1011-2025 / 1001-2025 0.5 2.6 0.5
MBM /PTB GPSPPP ME01 /PT13 1021-2021 / 1001-2025 0.3 3.1 1.8
MIKE/PTB GPSPPP MI04 /PT13 1019-2023 / 1001-2025 0.3 2.8 1.3
MSL /PTB GPS P3 MS01 /PT13 1015-2021 / 1001-2025 0.7 3.2 1.9
MTC /PTB GPS P3 MC02 /PT13 NA_Al / 1001-2025 1.0 74.7 74.3 32.6 1411
NAO /PTB GPS MC NAT2 /PT13 1012-2022 / 1001-2025 2.0 3.9 1.9
NICT/PTB GPSPPP NC5S /PT13 1001-2022 / 1001-2025 0.3 2.2 1.6
NIM /PTB GPSPPP IM02 /PT13 1001-2022 / 1001-2025 0.3 2.2 1.6
NIMB/PTB GPS P3 MB02 /PT13 2002-2026 / 1001-2025 0.7 7.0 0.2
NIMT/PTB GPS P3 MTTN /PT13 1016-2025 / 1001-2025 0.7 2.5 0.2
NIS /PTB GPS P3 IS_5 /PT13 2001-2021 / 1001-2025 0.7 7.3 2.1
NMIJ/PTB GPSPPP NM0F /PT13 1015-2022 / 1001-2025 0.3 3.1 1.8
NMLS/PTB GPSPPP LSM2 /PT13 1011-2023 / 1001-2025 0.3 2.9 1.5
NPLI/PTB GPSPPP LIAA /PT13 1011-2024 / 1001-2025 0.3 2.7 1.0
NRC /PTB GPSPPP NRCC /PT13 1015-2023 / 1001-2025 0.3 2.8 1.3
NRL /PTB NL
NSAI/PTB NL
NTSC/PTB GPSPPP NT03 /PT13 1016-2018 / 1001-2025 0.3 3.8 2.7
ONBA/PTB GPS MC ON__ /PT13 1014-2021 / 1001-2025 2.0 3.5 1.9
ONRJ/PTB GPSPPP RJ04 /PT13 1012-2020 / 1001-2025 0.3 3.4 2.4
ORB /PTB GPSPPP OR5Z /PT13 1017-2023 / 1001-2025 0.3 2.9 1.4
PL /PTB GPSPPP PL_5 /PT13 1012-2024 / 1001-2025 0.3 2.7 1.1
SASO/PTB GPSPPP SAS0 /PT13 1020-2017 / 1001-2025 0.5 3.9 3.0
SCL /PTB GPSPPP SC05 /PT13 1011-2018 / 1001-2025 0.3 3.9 3.0
SG /PTB GPSPPP SG02 /PT13 1018-2023 / 1001-2025 0.3 2.8 1.2
SIQ /PTB GPSPPP SI01 /PT13 1013-2019 / 1001-2025 0.3 4.3 2.5
SMD /PTB GPSPPP SD31 /PT13 1201-2020 / 1001-2025 0.3 4.6 2.3
SMU /PTB GPS MC SM00 /PT13 1202-2024 / 1001-2025 1.5 6.2 1.0
TL /PTB GPSPPP TLT5 /PT13 1001-2022 / 1001-2025 0.3 2.1 1.5
TP /PTB GPSPPP TP02 /PT13 1013-2021 / 1001-2025 0.3 3.2 2.1
UA /PTB GPS MC UA05 /PT13 2003-2018 / 1001-2025 3.0 7.6 2.9
UAE /PTB GPS P3 AE02 /PT13 2001-2025 / 1001-2025 0.7 7.0 0.2
UME /PTB GPSPPP UM01 /PT13 1011-2016 / 1001-2025 0.3 22.5 22.3
UZ /PTB GPSPPP UZ__ /PT13 1013-2025 / 1001-2025 0.3 2.5 0.3
VMI /PTB GPS P3 VM02 /PT13 1011-2022 / 1001-2025 0.7 3.1 1.8
ZA /PTB GPS P3 ZA02 /PT13 1018-2018 / 1001-2025 15.0 3.8 2.8
Link Type Equipment Cal_ID uStb/ns uCal/ns uAg/ns Al/ns YYMM
CH /PTB TWGPPP CH01 /PTB05 0623-2024 0.3 1.2 0.7
IT /PTB TWGPPP IT01 /PTB05 0622-2024 0.3 1.2 0.7
NIST/PTB TWGPPP NIST01/PTB05 0593-2024 0.3 2.0 0.4
NPL /PTB TWGPPP NPL02 /PTB05 0620-2024 0.3 1.2 0.7
OP /PTB TWSDRR OP51 /PTB55 0624-2024 0.3 1.2 0.7
ROA /PTB TWGPPP ROA01 /PTB05 0618-2024 0.3 1.2 0.7
SP /PTB TWGPPP SP01 /PTB05 0621-2024 0.3 1.2 0.7
SU /PTB TWSDRR SU51 /PTB53 0626-2026 0.3 3.0 0.0
USNO/PTB TWGPPP USNO01/PTB05 0534-2021 0.3 2.4 2.2
VSL /PTB TWGPPP VSL01 /PTB05 0616-2024 0.3 1.3 0.7