FW: correction for tzdata/leapseconds
Please include Michael Deckers in any replies; Michael is not part of the time zone mailing list. --ado -----Original Message----- From: Michael Deckers [SMTP:Michael.Deckers@mch6.siemens.de] Sent: Thursday, July 22, 1999 6:29 AM To: tz@elsie.nci.nih.gov Subject: correction for tzdata/leapseconds Just a quibble in the file "@(#)leapseconds 7.11" in ftp://elsie.nci.nih.gov/pub/tzdata1999d.tar.gz: # The International Earth Rotation Service periodically uses leap seconds # to keep UTC to within 0.9 s of TAI (atomic time); see ***************** This becomes correct only with UT1 in place of TAI. For instance: within 0.9 s of UT1 (Universal Time 1, the primary time scale measuring the rotation of the Earth) Since the rates of UTC and TAI are the same, the difference between TAI and UTC increases at each instant a leap second is inserted in UTC; currently it is 32 s. ------------------------------------------------------------------------ Michael H Deckers email: Michael.Deckers@mch6.siemens.de ---------------------------- end of mail -------------------------------
"Olson, Arthur David (NCI)" wrote on 1999-07-22 13:43 UTC:
From: Michael Deckers [SMTP:Michael.Deckers@mch6.siemens.de] Sent: Thursday, July 22, 1999 6:29 AM To: tz@elsie.nci.nih.gov Subject: correction for tzdata/leapseconds
Just a quibble in the file "@(#)leapseconds 7.11" in ftp://elsie.nci.nih.gov/pub/tzdata1999d.tar.gz:
# The International Earth Rotation Service periodically uses leap seconds # to keep UTC to within 0.9 s of TAI (atomic time); see ***************** This becomes correct only with UT1 in place of TAI.
I agree. The string "TAI (atomic time)" should definitely be replaced by something like "UT1 (astronomical earth time, corrected for known periodic fluctuations)". See also http://www.cl.cam.ac.uk/~mgk25/volatile/ITU-R-TF.460-4.pdf http://www.cl.cam.ac.uk/~mgk25/volatile/astronomical-time.pdf for the official definition of UTC, but please don't include these URLs (only temporarily available). Markus -- Markus G. Kuhn, Computer Laboratory, University of Cambridge, UK Email: mkuhn at acm.org, WWW: <http://www.cl.cam.ac.uk/~mgk25/>
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Markus Kuhn
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Olson, Arthur David (NCI)