Leap Second and the International Telecommunication Union (ITU)

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Leap Second and the International
Telecommunication Union (ITU)

• Masatoshi Ohishi
• NAOJ

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Summary

• International Telecommunication Union (ITU) has
  discussed if it is appropriate to eliminate leap
  second. UTC UT1 ? 1 hour ? UTC
  will be a continuous time scale
• Many governments support elimination of leap
  second, but several oppose. ? no consensus
  yet.
• It may impact current software used in
  astronomy. Be prepared !

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Leap Second

• An intentional time step of one second used to
  adjust coordinated universal time (UTC) to ensure
  approximate agreement with UT1. 1972
• UTC - UT1 lt 0.9 second
• UTC, UT1 are maintained by BIPM and IERS,
  respectively.
• BIPM - Le Bureau International des Poids et
  Mesures (The International Bureau
  of Weights and Measures)
• IERS International Earth Rotation and
  Reference Systems Service
• Next insertion Dec 31 23h 59m 60s, 2008

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(No Transcript)
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ITU

• A specialized agency under the UN.
• http//www.itu.int/
• ITU convention ? binds governments that
  ratified
• Three sectors
• ITU-R wireless communications
  satellite orbits
• ITU-T wired communications
• ITU-D support ICT in developing countries

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Members of the ITU

• Member States (191)
• Sector Members such as private companies (579)
• Regional Groups
• International Organizations such as IAU, URSI

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World Radiocommunication Conference

• Revision of the Radio Regulations that has the
  status of an international treaty.
• Study Groups, Working Parties consider technical
  aspects of issues to be discussed in WRCs.

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Study Groups

• SG 1Spectrum Management
• SG 3Radio Wave Propagation
• SG 4Satellite Services
• SG 5Terrestrial Services
• SG 6Broadcasting Service
• SG 7Science Services
• SC Special Committee

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SG 7

• WP 7A Time signals and frequency standard
  emissions
• WP 7B Space radio systems
• WP 7C Earth-exploration satellite
• systems and meteorological elements
• WP 7D Radio Astronomy

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Recommendations

• The ITU-R Recommendations provide a body of
  technical, operational and regulatory /
  procedural information that has been agreed upon
  by the participating administrations.
• RA series Radio Astronomy
• TF series Time signals and frequency
  standards emissions

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Rec. ITU-R TF.460-6Standard-frequency and
time-signal emissions

• Incorporated by reference in the Radio
  Regulations ? international treaty !
• Recommends
• that all standard-frequency and time-signal
  emissions conform as closely as possible to
  coordinated universal time (UTC) (see Annex 1)
• Annex 1 gives definitions of UT, TAI, UTC and
  leap second

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Proposal

• the application of leap second adjustments to UTC
  should cease on 1 January five years after
  approval by the appropriate World
  Radiocommunication Conference
• Set the targeted Conference to WRC-2007 (2011)

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Why eliminate ?

• NTP sometimes fails to synchronize.
• Some navigation satellites (GPS, Galileo,
  GLONASS, etc.) fail to synchronize.
• Human error to adjust the jumps.
• And many other reasons ? discussion since 1999

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Last WP7A meeting

• October 8 13, 2008, Geneva
• The chairman intended to approve the draft
  revision of Rec TF.460.
• No consensus was reached due to objections by
  some administrations.
• Further discussion in its October 2009 meeting

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Support / Neutral / Opposition

• F, D, R, US, I
• ESA, BdL (Bureau des Longitudes), Galileo, CCTF
  (Consultative Committee for Time and Frequency),
  ITU-T

• IAU, AAS, JPL, URSI com. J, NRAO
• UK, China, P.R.,

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What we could/should do

• Survey the possible impact to our
  software/hardware used in astronomical research,
  and prepare for the modification.
• If unhappy to the elimination, talk to (condemn
  ?) your government / IAU / URSI, etc.

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Summary

• International Telecommunication Union (ITU) has
  discussed if it is appropriate to eliminate leap
  second. UTC UT1 ? 1 hour ? UTC
  will be a continuous time scale
• Many governments support elimination of leap
  second, but several oppose. ? no consensus
  yet.
• It may impact current software used in
  astronomy. Be prepared !