[LEAPSECS] New terminology will be needed.

[Hooke, Adrian J (9000)]

-----Original Message-----
From:  Steve Allen
Sent: Thursday, January 05, 2012 9:56 AM
To: Leap Second Discussion List
Subject: Re: [LEAPSECS] New terminology will be needed.
... but wait, there's more
-------------------------------

FYI: for spaceflight use we prefer an internationally-standardized timecode which is just a straight binary count of TAI seconds and subseconds that have elapsed since the since the 1958 January 1 epoch (which conveniently pre-dates virtually all of the space age in terms of archiving space mission data):

http://public.ccsds.org/publications/SEA.aspx

http://public.ccsds.org/publications/archive/301x0b4.pdf
"Section 3.2:  The basic unit of time intended for correlation with Earth-based clocks is the second. The basic unit of time represented by the value of the T-Field is required to be defined in the metadata. The metadata also defines the epoch of the time and the number of octets of basic
and fractional time units. This metadata can be provided by the P-field if self-identification is employed or by metadata external to the P-field. The CCSDS-Recommended epoch is that of 1958 January 1 (TAI) and the recommended time unit is the second, using TAI as reference time scale, for use as a level 1 time code. This time code is not UTC-based and leap-second corrections do not apply."

Note the "P-field", which provides an internationally-standardized way of identifying the semantics of the remainder of the code. Redefining the semantics of UTC without a corresponding standard way of positively identifying the change seems just weird.

Adrian J. Hooke
Chairman, CCSDS Engineering Steering Group
Space Communications and Navigation Office
NASA Headquarters