Leap Second 01-01-2017: a place to post issues and tips

[Kate Stevenson]

Greetings!

The NESC forum seems like the right place to have somewhere for stations to exchange information about predictions and time biases following the leap second - and whatever else folks would like to say about it.

Please use this thread to post updates for the community about any successes or issues you have related to the leap second.

Happy tracking!
Kate
NASA SLR OC

[Randall Ricklefs]

Below is the "official" notice of the ILRS Leap Second Procedure" sent several times this year.

Dear Prediction, Station, and Analyst Colleagues,

As you are probably aware, there is a leap second at the end of December 31 this year. Our last couple of leap second experiences could have been better. This time, the ILRS has adopted the following simplified policy approved by the Data Formats and Procedures Standing Committee and the ILRS Central Bureau.

1) Stations:

    - On December 31, track as normal up until the end of the UTC day.

    - On January 1 UTC, be sure your stations clock is updated, and switch to the CPF files that start on

        January 1. Do NOT use CPF files that start in December.

    - Tracking a satellite pass through the December 31/January 1 crossover will probably not work

        properly.

2) Prediction providers:

    - Most of you do not need to change anything. It does not matter whether you are setting the leap

        second flag or not, as long as it it is set consistent with the CPF document.

    - The CPF files starting on January 1 and thereafter MUST NOT have the leap second flag set to '1'.

        After the last leap second, one or two providers did not reset the flag for a few days into January.

    - Be sure to have your leap second files updated properly.

3) Analysts:

    - Be sure to update your leap second files!

This procedure should be easier than dealing with leap second flags, although some passes that span the leap second will be lost. Let us know if you have any issues with this procedure.

Best regards,
Randall Ricklefs
For the ILRS Central Bureau

[Matt Wilkinson]

Happy New Year everyone

So far today at Herstmonceux, we had a mixed experience from SLR cpf predictions after the leap second. There were time bias issues with the Jason satellites using the CNES cpf predictions.  Also Galileo205 was off by 1 second using the ESA predictions, I've not yet seen if this holds for all Galileo. HY2A and Kompsat5 were also off on the MCC predictions. Most other satellites are well predicted. Successfully tracking Lageos with JAXA cpfs.

CPF predictions are compared here http://sgf.rgo.ac.uk/qualityc/cpf_qc_resids.html each day and it is clear that there are conflicting predictions

[Dan O'Gara]

Tracking at TLRS-4. For day 003/004UT have needed to use +/-2us range biases for Ajisai (SGF#5022) and LAGEOS1/2(SGF35021).

The LAGEOS would range bias would drift from +2us to -2us during the pass. On a 78 degree STELLA we got 20 returns at culmination, but none before or after culmination. This is very unusual.