NET TIME AND FREQUENCY BULLETIN 

NlSTlR 5057-1 2 

NO. 481 DECEMBER 1997 

1. GENERAL BACKGROUND INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 

2. TIME SCALE INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 

3. UT1 CORRECTIONS AND LEAP SECOND ADJUSTMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 

4. PHASE DEVIATIONS FOR WWVB AND LORAN-C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 

5. GOES TIME CODE INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 

6. BROADCAST OUTAGES OVER FIVE MINUTES AND WWVB 

PHASE PERTURBATIONS ...................................................... 5 

7. NOTES ON NlST TIME SCALES AND PRIMARY STANDARDS . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 

8. BIBLIOGRAPHY .............................................................. 

9. SPECIAL ANNOUNCEMENTS ................................................... 7 

This bulletin is published monthly. Address correspondence to: 

Gwen E. Bennett, Editor 

Time and Frequency Division 

National Institute of Standards and Technology 

325 Broadway 

Boulder, CO 80303-3328 

(303) 497-3295 

NOTE TO SUBSCRIBERS: Please include your address label (or a copy) 

with any correspondence regarding this bulletin. 

U.S. DEPARTMENT OF COMMERCE, William M. Daley, Secretary 

TECHNOLOGY ADMINISTRATION, Mary L. Good, Under Secretary for Technology 

NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY, Robert Hebner, Acting Deputy Director 

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1. GENERAL BACKGROUND INFORMATION 

ABBREVIATIONS AND ACRONYMS USED IN THIS BULLETIN 

NOV 1997 MJD UTI - UTC(N1ST) 

BIPM - CClR - cs 

GOES - GPS 

IERS - LORAN - MC 

MJD - 

NVLAP - NIST - NOAA - SI 

TA 

TAI 

USNO - 

UTC - VLF 

UTC(USN0,MC) - UTC(NIST) 

Bureau International des Poids et Mesures 

International Radio Consultative Committee 

Cesium standard 

Geostationary Operational Environmental Satellite 

Global Positioning System 

International Earth Rotation Service 

Long Range Navigation 

Master Clock 

Modified Julian Date 

National Voluntary Laboratory Accreditation Program 

National Institute of Standards & Technology 

National Oceanic and Atmospheric Administration ns - nanosecond 

International System of Units PS - microsecond 

Atomic Time ms - millisecond 

International Atomic Time S - second 

United States Naval Observatory min - minute 

Coordinated Universal Time 

very low frequency 

2. TIME SCALE INFORMATION 

~~ P~ I-P 6 50758 +317 ms 5 ns I 

13 50765 +299 ms 3 ns 

20 50772 +287 ms 3 ns 

27 50779 +275 ms 5 ns 

3. UTI CORRECTIONS AND LEAP SECOND ADJUSTMENTS 

The master clock pulses used by the WWV, WWVH, WWVB, and GOES time code transmissions are referenced to the 

UTC(NIST1 time scale. Occasionally, 1 s is added to the UTC time scale. This second is called a leap second. Its purpose 

is to keep the UTC time scale within kO.9 s of the UTI astronomical time scale, which changes slightly due to variations 

in the rotation of the Earth. 

Positive leap seconds, beginning at 23 h 59 min 60 s UTC and ending at 0 h 0 min 0 s UTC, were inserted in the UTC 

timescale on 30 June 1972, 1981 -1 983, 1985,1992, 1993, 1994, and 1997, and on 31 December 1972-1 979,1987, 

1989, 1990, and 1995. 

The use of leap seconds ensures that UTl - UTC will always be held within +0.9 s. The current value of UTI - UTC 

is called the DUTl correction. DUTl corrections are broadcast by WWV, WWVH, WWVB, and GOES and are printed 

below. These corrections may be added to received UTC time signals in order to obtain UT1. 

+0.4 s beginning 0000 UTC 18 September 1997 

+0.3 s beginning 0000 UTC 30 October 1997 

+0.2 s beginning 0000 UTC 18 December 1997 

DUTl = UT1 - UTC = 

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4. PHASE DEVIATIONS FOR WWVB AND LORAN-C 

WWVB - The values shown for WWVB are the time difference between the time markers of the UTC(NIST) time 

scale and the first positive-going zero voltage crossover measured at the transmitting antenna. The 

uncertainty of the individual measurements is k0.5 ps. The values listed are for 1300 UTC. 

The values shown for Loran-C represent the daily accumulated phase shift (in ns). The phase shift is 

measured by comparing the output of a Loran receiver to the UTC(NIST) time scale for a period of 24 h. 

If data were not recorded on a particular day, the symbol (-) is printed. 

LORAN-C - 

The master stations monitored are Dana, IN (8970) and Fallon, NV (9940). The monitoring is done from 

the NlST laboratories in Boulder, CO. 

Note: The values shown for Loran-C are in nanoseconds. 

UTC(NIST)-WWVB(GO kHz1 UTC(NIST) - LORAN PHASE (nsl 

ANTENNA PHASE LORAN-C (DANA) LORAN-C (FALLON)' 

DATE MJD bs) (8970) (9940) 

11/01/97 50753 5.74 +361 +116 

1 1 I02197 50754 5.73 +114 - 32 

1 1 I03197 50755 5.73 - 400 -215 

1 1104197 50756 5.71 + 84 -157 

11 I05197 50757 5.75 -105 -216 

1 1 I06197 50758 5.75 - 5 + 366 

1 1 I07197 50759 5.75 + 58 +155 

1 1108197 50760 5.75 - 377 +1 

1 1109197 50761 5.77 + 445 - 300 

1 1 I1 0197 50762 5.77 -159 + 80 

1 111 1197 50763 5.78 - 263 -112 

11 I1 2/97 50764 5.73 -178 - 244 

1 1 I1 3/97 50765 5.77 - 440 + 320 

1 1 I1 4/97 50766 5.66 -160 -118 

11 I1 5/97 50767 5.76 +121 +32 

11 I1 6/97 50768 5.76 -107 - 200 

1 1 I1 7/97 50769 5.83 + 228 + 269 

1 1 I1 8/97 50770 5.75 - 669 + 207 

1 1 I1 9/97 50771 5.74 +131 +148 

1 1120197 50772 5.65 +9 -17 

1 1 I21 I97 50773 5.65 +123 + 65 

11/22/97 50774 5.66 + 403 + 205 

1 1123197 50775 5.67 -126 -194 

1 1 I24197 50776 5.68 - 72 - 323 

1 1/25/97 50777 5.69 -141 +218 

1 1126197 50778 5.68 -158 +258 

1 1127197 50779 5.68 - 92 - 220 

1 1/28/97 50780 5.71 +62 -110 

1 1 I29197 50781 5.71 +5 - 286 

1 1 I30197 50782 5.71 - 92 +126 

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4. PHASE DEVIATIONS FOR WWVB AND LORAN-C 

WWVB - The values shown for WWVB are the time difference between the time markers of the UTC(NIST) time 

scale and the first positive-going zero voltage crossover measured at the transmitting antenna. The 

uncertainty of the individual measurements is k0.5 ps. The values listed are for 1300 UTC. 

The values shown for Loran-C represent the daily accumulated phase shift (in ns). The phase shift is 

measured by comparing the output of a Loran receiver to the UTC(NIST) time scale for a period of 24 h. 

If data were not recorded on a particular day, the symbol (-1 is printed. 

LORAN-C - 

The master stations monitored are Dana, IN (8970) and Fallon, NV (9940). The monitoring is done from 

the NlST laboratories in Boulder, CO. 

Note: The values shown for Loran-C are in nanoseconds. 

UTC(NIST)-WWVB(GO kHz1 UTC(NIST) - LORAN PHASE (nsl 

ANTENNA PHASE LORAN-C (DANA) LORAN-C (FALLON)' 

DATE MJD bs) (8970) (9940) 

1 1 I01 I97 50753 5.74 +361 +116 

1 1 102197 50754 5.73 +114 - 32 

1 1 I03197 50755 5.73 - 400 -215 

1 1104197 50756 5.71 + 84 -157 

11 I05197 50757 5.75 -105 -216 

1 1 I06197 50758 5.75 - 5 + 366 

1 1107197 50759 5.75 + 58 +155 

1 1108197 50760 5.75 - 377 +1 

1 1109197 50761 5.77 + 445 - 300 

1 1 I1 0197 50762 5.77 -159 + 80 

1 111 1 I97 50763 5.78 - 263 -112 

11 I1 2/97 50764 5.73 -178 - 244 

1 1 I1 3/97 50765 5.77 - 440 + 320 

1 1 I1 4/97 50766 5.66 - 160 -118 

11 I1 5/97 50767 5.76 +121 +32 

11 I1 6/97 50768 5.76 - 107 - 200 

1 1 I1 7/97 50769 5.83 + 228 + 269 

1 1 I1 8/97 50770 5.75 - 669 + 207 

1 1 I1 9/97 50771 5.74 +131 +148 

1 1120197 50772 5.65 +9 - 17 

11/21/97 50773 5.65 +123 + 65 

11/22/97 50774 5.66 + 403 + 205 

1 1123197 50775 5.67 -126 - 194 

1 1 I24197 50776 5.68 - 72 - 323 

1 1/25/97 50777 5.69 -141 +218 

1 1126197 50778 5.68 -158 +258 

1 1127197 50779 5.68 - 92 - 220 

1 1128197 50780 5.71 +62 - 110 

1 1 I29197 50781 5.71 +5 - 286 

1 1130197 50782 5.71 - 92 +126 

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5. GOES TIME CODE INFORMATION 

Station 

WWVB 

wwv 

WWVH 

A. TIME CODE PERFORMANCE (1-31 November 1997) 

GOESIEast: 

respect to UTC(NIST1. 

GOES/West: 

respect to UTC(NIST1. 

Currently using the GOES-8 satellite at 75O west longitude. Timing uncertainty is * 100 ps with 

Currently using the GOES-9 satellite at 135O west longitude. Timing uncertainty is +_lo0 ps with 

NOTE: The next anticipated WWVB service interruptions will be in December 1997. This interruption is 

needed to test the WWVB transmitters on the antenna system. The exact dates, start times, and durations 

will be posted at http://www.bldrdoc.gov/timefreq/vboutage.htrn when the information becomes available. 

NOV MJD Began Ended Freq. NOV MJD Began End 

1997 UTC UTC 1997 UTC UTC 

1116 50758 1700 1900 60 kHz 

6. BROADCAST OUTAGES OVER 5 MINUTES AND WWVB PHASE PERTURBATIONS 
Table 7.1 is a list of the parameters that are used to define UTC(NIST) with respect to our real-time scale ATI. To find 

the value of UTC(NIST) - AT1 at any time T (expressed as a Modified Julian Day, including a fraction if needed), the 

appropriate equation to use is the one for which the desired T is greater than or equal to the entry in the To column and 

less than the entry in the last column. The values of xis, x, and y for that month are then used in the equation below to 

find the desired value. The parameters x and y represent the offset in time and in frequency, respectively, between 

UTC(NIST) and AT1 ; the parameter xls is the number of leap seconds applied to both UTC(NIST) and UTC as specified by 

the IERS. Leap seconds are not applied to AT1. 

Jul 96 

Aug 96 

Sep 96 

Oct 96 

Nov 96 

Dec 96+ 

Jan 97 

Feb 97 

Mar 97 

Apr 97 

May 97 

Jun 97 

Jul 97 

Aug 97 

Sep 97 

Oct 97 

Nov 97 

Dec 97 

Jan 98 

- 30 - 146604 -44.0 50265 50296 

- 30 - 147968 -44.5 50296 50327 

- 30 - 149347 -44.5 50327 50357 

- 30 - 150682 -44.0 50357 50388 

- 30 - 152046 -44.0 50388 5041 8 

- 30 - 153366 -43.8 5041 8 50434 

- 30 - 154066.8 -42.6 50434 50449 

- 30 - 154705.8 -42.5 50449 50480 

- 30 - 156023.3 -42.5 50480 50508 

- 30 - 15721 3.3 -42.7 50508 50539 

- 30 - 158537 -42.5 50539 50569 

- 30 - 15981 2 -43.0 50569 50600 

- 30 -161145 - 43 .O 50600 50630 

-31 - 162435 -43.0 50630 50661 

-31 - 163768 -43.0 50661 50692 

-31 - 165101 -42.5 50692 50722 

-31 - 166376 -42.0 50722 50753 

-31 - 167678 -42.0 50753 50783 

-31 - 168938 -42.5 50783 5081 4 

- 31 - 170255 -42.5" 50814 50845 

'Note rate change in mid-month 

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9. SPECIAL ANNOUNCEMENTS 

TRACEABLE FREQUENCY CALIBRATIONS 

(Now NVLAP Certified) 

Anyone needing traceable frequency calibrations can get them by subscribing to the NlST Frequency 

Measurement and Analysis Service. This service is offered on a lease basis by NET to provide an easy and 

inexpensive means to obtain traceability of a laboratory main oscillator and, in addition, to calibrate other devices 

in the lab. This service has been designed for ease of operation and as a practical lab calibration tool. 

All the equipment and software needed are provided by NIST. Users must provide their own oscillator(s) 

and an ordinary telephone line so that NIST can access the system by modem. A total of four oscillators can be 

calibrated at the same time. Radio signals from either Loran-C or GPS satellite are used. Results for either are at 

about the same accuracy. 

The calibration data are displayed in color and a graph is plotted daily for each oscillator connected. Data 

are also stored on disk. The user can call up any of the data and view them onscreen or in the form of plots. Many 

months of data can be plotted. 

The system plots are easy to read and understand. The system manual is written for easy understanding 

and the NlST staff is available by telephone to assist. The modem connection allows NlST to access the data and 

to prepare a monthly traceability report which is mailed to the user. 

Frequency sources of any accuracy can be calibrated. The FMAS is particularly useful at the highest levels 

of performance. This is because each user of the system contributes information and calibration data for the 

others. If an uncertainty arises, it is possible for NlST to call by modem to another user nearby. In this way 

problems in data interpretation can be resolved. 

NVLAP certification requirements for frequency measurement are met by following the NET-FMAS 

operating manual. This service does not eliminate the NVLAP audits but, when installed and operated per the NlST 

guidelines, audit requirements are easily met. 

NlST retains title to the equipment and supplies any needed system spares. Equipment that fails is 

replaced by overnight shipment. Training for use of the system is available if requested by the user. 

The NlST Frequency Measurement and Analysis Service provides a complete solution to nearly all 

frequency measurement and calibration problems. For a free information package, please call Michael Lombardi 

at (303) 497-321 2, or write to: Michael Lombardi, NIST, Division 847, 325 Broadway, Boulder, CO 80303. 

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