A leap second announcement from the USNO is attached; as well as a shar-format version of an updated "leapseconds" file. You'll now find "tzdata93b.tar.Z" on elsie.nci.nih.gov; the only change to it from "tzdata93.tar.Z" is the updated "leapseconds" file. --ado

From ntp-relay@ni.umd.edu Tue Feb 2 14:49:18 1993 Return-Path: <ntp-relay@ni.umd.edu> Received: from ni.umd.edu by elsie.nci.nih.gov (4.1/SMI-4.1) id AA02852; Tue, 2 Feb 93 14:49:14 EST Received: by ni.umd.edu id AA06039 (5.65c/IDA-1.4.4 for ntp-list); Tue, 2 Feb 1993 14:21:15 -0500 Received: from unbmvs1.csd.unb.ca by ni.umd.edu with SMTP id AA06030 (5.65c/IDA-1.4.4 for <NTP@NI.UMD.EDU>); Tue, 2 Feb 1993 14:20:50 -0500 Received: from unbmvs1.csd.unb.ca by UNBMVS1.csd.unb.ca (IBM MVS SMTP V2R1) with BSMTP id 3951; Tue, 02 Feb 93 15:20:05 AST Received: by UNBMVS1 (Mailer 15.14) id 5634; Tue, 02 Feb 93 15:18:57 AST Date: Tue, 02 Feb 93 15:18:57 AST From: LANG@unb.ca To: "NTP List" <NTP@NI.UMD.EDU> Subject: Leap Second Announcement from USNO Message-Id: <ID3951.D930202.T151859.LANG@unb.ca> Status: R

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File SER14 -- <930201.1735>

U.S. NAVAL OBSERVATORY WASHINGTON, DC 20392-5420

February 1, 1993 No. 55

TIME SERVICE ANNOUNCEMENT SERIES 14

UTC TIME STEP

1. The International Earth Rotation Service (IERS) has announced the Introduction of a time step to occur at the end of June 1993.

2. Coordinated Universal Time (UTC) will be retarded by 1.0s so that the sequence of dates of the UTC markers will be:

1993 June 30 23h 59m 59s 1993 June 30 23h 59m 60s 1993 July 01 0h 0m 0s

3. The difference between UTC and International Atomic Time TAI is:

from 1992 Jul 1, 0h UTC, to 1993 Jul.1, 0h UTC: TAI-UTC = +27s from 1993 Jul 1, 0h UTC, until further notice: TAI-UTC = +28s

4. The insertion of one leap second will be evident by the change of sign of the DUT1 correction which will become positive. Extrapolated values of DUT1 are distributed weekly in the IERS Bulletin A (Time Service Announcement Series 7).

5. All coordinated time scales will be affected by this adjustment. However, the Loran-C, GPS and OMEGA systems will not be adjusted physically. Tables of Coincidence (Time Service Announcement Series 9) will be issued for Loran-C. For GPS, the leap second correction contained within the UTC data of subframe 4, page 18 of the navigation message transmitted by the satellite will change.

Before the leap second

GPS-UTC = +8s (i.e., GPS is ahead of UTC by eight seconds).

After the leap second

GPS-UTC = +9s (i.e., GPS will be ahead of UTC by nine seconds).

The OMEGA Reference Ephoch (ORE) will change - that is, from 1 July 1993 (after the leap second) the OMEGA system will operate with the the beginning of segment one on seconds 42, 52, 02, 12, 22, and 32 of each minute.

GERNOT M. R. WINKLER Director Time Service Department

via: ============================================================================== Richard B. Langley Internet: LANG@UNB.CA or SE@UNB.CA Geodetic Research Laboratory BITnet: LANG@UNB or SE@UNB Dept. of Surveying Engineering Phone: (506) 453-5142 University of New Brunswick FAX: (506) 453-4943 Fredericton, N.B., Canada E3B 5A3 Telex: 014-46202 ============================================================================== --------------------- End of forwarded message ---------------------

: To unbundle, sh this file echo file 'leapseconds' >&2 cat >'leapseconds' <<'End of leapseconds' # @(#)leapseconds 7.6 # Allowance for leapseconds added to each timezone file. # The International Earth Rotation Service periodically uses leap seconds # to keep UTC to within 0.9 s of TAI (atomic time); see # Terry J Quinn, The BIPM and the accurate measure of time, # Proc IEEE 79, 7 (July 1991), 894-905. # There were no leap seconds before 1972, because the official mechanism # accounting for the discrepancy between atomic time and the earth's rotation # did not exist until the early 1970s. # The correction (+ or -) is made at the given time, so lines # will typically look like: # Leap YEAR MON DAY 23:59:60 + R/S # or # Leap YEAR MON DAY 23:59:59 - R/S # If the leapsecond is Rolling (R) the given time is local time # If the leapsecond is Stationary (S) the given time is GMT # Leap YEAR MONTH DAY HH:MM:SS CORR R/S Leap 1972 Jun 30 23:59:60 + S Leap 1972 Dec 31 23:59:60 + S Leap 1973 Dec 31 23:59:60 + S Leap 1974 Dec 31 23:59:60 + S Leap 1975 Dec 31 23:59:60 + S Leap 1976 Dec 31 23:59:60 + S Leap 1977 Dec 31 23:59:60 + S Leap 1978 Dec 31 23:59:60 + S Leap 1979 Dec 31 23:59:60 + S Leap 1981 Jun 30 23:59:60 + S Leap 1982 Jun 30 23:59:60 + S Leap 1983 Jun 30 23:59:60 + S Leap 1985 Jun 30 23:59:60 + S Leap 1987 Dec 31 23:59:60 + S Leap 1989 Dec 31 23:59:60 + S Leap 1990 Dec 31 23:59:60 + S Leap 1992 Jun 30 23:59:60 + S Leap 1993 Jun 30 23:59:60 + S End of leapseconds exit