Leap second announcement; updated "leapsecond" file

Arthur David Olson ado
Tue Feb 2 20:03:24 UTC 1993


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

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> Subject:     Leap Second Announcement from USNO
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> Comments:    Original-Date:         Tue, 2 Feb 1993 14:54:47 AST
> X-Reply-To: Richard Langley <lang at JUPITER.SUN.CSD.UNB.CA>
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> X-From: Richard Langley <lang at JUPITER.SUN.CSD.UNB.CA>
> Subject:      Leap Second Announcement from USNO
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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 at UNB.CA or SE at UNB.CA
>  Geodetic Research Laboratory              BITnet:   LANG at UNB or SE at 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



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