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<p class="MsoNormal">Cheryl – <o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">One of the primary reasons (but not the only reason) for using relative time is to circumvent concerns about the introduction of leap seconds.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Wouldn’t they be able to use relative time and not worry (as much) about leap seconds?<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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<div style="mso-element:para-border-div;border:none;border-top:dashed windowtext 1.0pt;padding:1.0pt 0in 0in 0in">
<p class="MsoNormal" style="border:none;padding:0in">Dan Oltrogge <span style="font-size:13.5pt">
҉</span> Director, Integrated Operations and Research <span style="font-size:13.5pt">
҉</span> COMSPOC Corporation <span style="font-size:13.5pt">҉</span> 719-482-4552
<span style="font-size:13.5pt">҉</span> <a href="mailto:dan@comspoc.com"><span style="color:blue">dan@comspoc.com</span></a><o:p></o:p></p>
</div>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
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<div style="border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0in 0in 0in">
<p class="MsoNormal"><b>From:</b> Gramling, Cheryl J. (GSFC-5900) <cheryl.j.gramling@nasa.gov>
<br>
<b>Sent:</b> May 10, 2021 09:52<br>
<b>To:</b> Lamy Alain <Alain.Lamy@cnes.fr>; moims-nav-exec@mailman.ccsds.org; Daniel Oltrogge <dan@comspoc.com><br>
<b>Cc:</b> Gramling, Cheryl J. (GSFC-5900) <cheryl.j.gramling@nasa.gov><br>
<b>Subject:</b> Re: [EXTERNAL] Re: [MOIMS-NAV-EXEC] leap second flagging<o:p></o:p></p>
</div>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#1F3864">Ralph, Alain, All,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#1F3864"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#1F3864">Thank you for the info and feedback.
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#1F3864">One concern is to provide information content that encompasses existing messages in the SSA community. The Cislunar SSA Steering group felt it was important
to be as explicit as possible, which aligns with the philosophy applied to other information in the OCM.
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#1F3864"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#1F3864">Here are two options the Cislunar SSA Steering Group identified as possibilities; this does not preclude other options:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#1F3864"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Helvetica",sans-serif">OCM META provides for TAIMUTC_AT_TZERO and EOP_SOURCE.<o:p></o:p></span></p>
<ul style="margin-top:0in" type="disc">
<li class="MsoListParagraphCxSpFirst" style="margin-left:-.25in;mso-add-space:auto;mso-list:l0 level1 lfo3">
<span style="font-size:10.0pt;font-family:"Helvetica",sans-serif">Option 1: Break up SSA Message for one before and one after Leap. Include OCM META flag to indicate leap occurred and # of integer seconds lept so user knows time offset of new message is bc
of leap; message that follows the leap would have new TAIMUTC_AT_TZERO.<o:p></o:p></span></li><li class="MsoListParagraphCxSpLast" style="margin-left:-.25in;mso-add-space:auto;mso-list:l0 level1 lfo3">
<span style="font-size:10.0pt;font-family:"Helvetica",sans-serif">Option 2: Use two subsequent Orbit Time History blocks, breaking across the leap, using ORB_PREV_ID to link the two blocks in sequence. OCM META include new field of LEAP_TIME followed by integer
number of seconds applied at that time. <o:p></o:p></span></li></ul>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#1F3864"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#1F3864"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#1F3864">Regards,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#1F3864">Cheryl<o:p></o:p></span></p>
<div>
<div>
<p class="MsoNormal"><span style="color:black">-------<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Lucida Grande";color:black">Cheryl Gramling<br>
NASA/GSFC/590<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Lucida Grande";color:black">Mission Engineering and Systems Analysis Division</span><span style="color:black"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Lucida Grande";color:black">Assoc. Chief for Technology</span><span style="color:black"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Lucida Grande";color:black">Goddard Senior Fellow<br>
<a href="applewebdata://C044DB7D-E97B-4942-B8FB-61DE66DC36D1/cheryl.j.gramling@nasa.gov"><span style="color:#954F72">cheryl.j.gramling@nasa.gov</span></a><br>
[O] 301-286-8002</span><span style="color:black"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Lucida Grande";color:black">[C] 240-328-5517</span><span style="color:black"><o:p></o:p></span></p>
</div>
</div>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#1F3864"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#1F3864"><o:p> </o:p></span></p>
<div style="border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in">
<p class="MsoNormal"><b><span style="font-size:12.0pt;color:black">From: </span></b><span style="font-size:12.0pt;color:black">MOIMS-NAV-EXEC <<a href="mailto:moims-nav-exec-bounces@mailman.ccsds.org">moims-nav-exec-bounces@mailman.ccsds.org</a>> on behalf
of Lamy Alain <<a href="mailto:Alain.Lamy@cnes.fr">Alain.Lamy@cnes.fr</a>><br>
<b>Date: </b>Monday, May 10, 2021 at 11:32 AM<br>
<b>To: </b>"<a href="mailto:moims-nav-exec@mailman.ccsds.org">moims-nav-exec@mailman.ccsds.org</a>" <<a href="mailto:moims-nav-exec@mailman.ccsds.org">moims-nav-exec@mailman.ccsds.org</a>>, "Oltrogge, Daniel" <<a href="mailto:doltrogge@comspoc.com">doltrogge@comspoc.com</a>><br>
<b>Subject: </b>[EXTERNAL] Re: [MOIMS-NAV-EXEC] leap second flagging<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<p class="MsoNormal"><span lang="FR" style="color:#1F497D">Hi, </span><o:p></o:p></p>
<p class="MsoNormal"><span lang="FR" style="color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D">Just one thought:</span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D">I was wondering why these leap seconds would have to be in the message, as you can find them everywhere.
</span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D">There is one case where there could some ambiguity: for predictions when a planned leap second may be taken into account or not.
</span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D">But I don’t know if that’s a good enough reason to have that the leap seconds in the message.
</span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D">Alain</span><o:p></o:p></p>
<p class="MsoNormal"><span lang="FR" style="color:#1F497D"> </span><o:p></o:p></p>
<div>
<div style="border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0in 0in 0in">
<p class="MsoNormal"><b>From:</b> MOIMS-NAV-EXEC <<a href="mailto:moims-nav-exec-bounces@mailman.ccsds.org">moims-nav-exec-bounces@mailman.ccsds.org</a>>
<b>On Behalf Of </b><a href="mailto:Ralph.Kahle@dlr.de">Ralph.Kahle@dlr.de</a><br>
<b>Sent:</b> lundi 10 mai 2021 16:59<br>
<b>To:</b> <a href="mailto:moims-nav-exec@mailman.ccsds.org">moims-nav-exec@mailman.ccsds.org</a><br>
<b>Subject:</b> [MOIMS-NAV-EXEC] leap second flagging<o:p></o:p></p>
</div>
</div>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal"><span lang="DE">Dear all,</span><o:p></o:p></p>
<p class="MsoNormal">Regarding the flagging of leap seconds in orbit products please find an example below that we use at GSOC:<o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal"><span lang="DE"><img border="0" width="930" height="129" style="width:9.6904in;height:1.3452in" id="Grafik_x0020_1" src="cid:image001.png@01D745C5.79BBBEA0"></span><o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal">Would something like this help the cislunar group and could be implemented into our messages?<o:p></o:p></p>
<p class="MsoNormal">Best,<o:p></o:p></p>
<p class="MsoNormal">Ralph<o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
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</span><b><span style="font-family:"Arial",sans-serif;color:dimgray;mso-fareast-language:DE">Ralph Kahle</span></b><span style="font-family:"Arial",sans-serif;color:dimgray;mso-fareast-language:DE">
</span><span style="font-size:8.5pt;font-family:"Arial",sans-serif;color:dimgray;mso-fareast-language:DE">| Head of Flight Dynamics Services
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