<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body style="overflow-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;">Hello - thinking of it : <div>there are very few UCD for rotational quantities. For solar system objects the reference src.orbital may be misleading, and some services use phys.obliquity for the spin direction (angle between the axis and the orbital plane). It may be a better choice also in this case (at least this is not a position angle, indeed).</div><div><br></div><div>Cheers</div><div>Stéphane</div><div><div><br><blockquote type="cite"><div>Le 21 mars 2025 à 18:09, Baptiste Cecconi via semantics <semantics@ivoa.net> a écrit :</div><br class="Apple-interchange-newline"><div><meta http-equiv="content-type" content="text/html; charset=utf-8"><div style="overflow-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;">Thanks all for your answers, I started a draft answer in Slack and then I saw this set of emails. <div><br></div><div>In short, yes, <span style="font-family: monospace;">src.orbital.inclination</span> is probably the best shot at this point, since it is already used with the same context.</div><div><br></div><div>Cheers</div><div>Baptiste</div><div><div><br><blockquote type="cite"><div>Le 21 mars 2025 à 11:22, Stéphane Erard via semantics <semantics@ivoa.net> a écrit :</div><br class="Apple-interchange-newline"><div><meta http-equiv="content-type" content="text/html; charset=utf-8"><div style="overflow-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;">Hello<div><br></div><div><br></div><div>In the EPN-TAP interface to exoplanet.eu, we're using src.orbital.inclination for this angle.</div><div>- although intended for inclination of an orbit on the ecliptic (in the Solar System), the UCD refers to a generic orbital inclination and seems acceptable in this context.</div><div>This UCD is also used in ESAsky, which takes the values from <a href="http://exoplanet.eu/">exoplanet.eu</a></div><div><br></div><div>Hope this helps</div><div><br></div><div><div><div dir="auto" style="overflow-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;"><div dir="auto" style="overflow-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;"><div style="orphans: 2; widows: 2; margin: 0px;"><font face="Helvetica" style="font-variant-ligatures: normal; font-variant-alternates: normal; font-variant-numeric: normal; font-variant-east-asian: normal; font-variant-position: normal; font-size: 12px; line-height: normal;">Stéphane Erard</font></div><div style="orphans: 2; widows: 2; margin: 0px;"><font face="Helvetica" style="font-variant-ligatures: normal; font-variant-alternates: normal; font-variant-numeric: normal; font-variant-east-asian: normal; font-variant-position: normal; font-size: 12px; line-height: normal;">____________________________________________</font></div><div style="orphans: 2; widows: 2; margin: 0px;"><font face="Helvetica" style="font-variant-ligatures: normal; font-variant-alternates: normal; font-variant-numeric: normal; font-variant-east-asian: normal; font-variant-position: normal; font-size: 12px; line-height: normal;">LIRA, Observatoire de Paris</font></div><div style="orphans: 2; widows: 2; margin: 0px;"><font face="Helvetica" style="font-variant-ligatures: normal; font-variant-alternates: normal; font-variant-numeric: normal; font-variant-east-asian: normal; font-variant-position: normal; font-size: 12px; line-height: normal;">5 place Jules Janssen </font><span class="Apple-style-span" style="font-size: 12px;">F-92195 Meudon cédex, France</span></div><div style="orphans: 2; widows: 2; margin: 0px;"><font face="Helvetica" style="font-variant-ligatures: normal; font-variant-alternates: normal; font-variant-numeric: normal; font-variant-east-asian: normal; font-variant-position: normal; font-size: 12px; line-height: normal;"><i>tel</i> : 33 1 45 07 78 19 </font><span class="Apple-style-span" style="font-size: 12px;"><i>fax</i> : 33 1 45 34 76 83</span></div><div style="orphans: 2; widows: 2; margin: 0px;"><font face="Helvetica" style="font-variant-ligatures: normal; font-variant-alternates: normal; font-variant-numeric: normal; font-variant-east-asian: normal; font-variant-position: normal; font-size: 12px; line-height: normal;"><i>e-mail : stephane.erard@obspm.fr</i></font></div><div><font face="Helvetica" style="font-variant-ligatures: normal; font-variant-alternates: normal; font-variant-numeric: normal; font-variant-east-asian: normal; font-variant-position: normal; font-size: 12px; line-height: normal;"><i><br></i></font></div></div></div></div><div><br><blockquote type="cite"><div>Le 20 mars 2025 à 21:41, Kelle Cruz via semantics <semantics@ivoa.net> a écrit :</div><br class="Apple-interchange-newline"><div><div dir="ltr"><div>Hi folks IVOA folks,</div><div><br></div><div>(I posted this question in Slack but didn't get a response. I found these email addresses on the wiki and am giving them a try. If there's a better place for discussion, please let me know.)</div><div><br></div><div>What’s the best UCD to use for the inclination angle of a star? That is, the angle of the star’s rotation axis w.r.t. us. Also known as “viewing angle” or the i in vsin(i). </div><div><br></div><div>I don’t think it’s <font face="monospace">src.orbital.inclination</font>. But <font face="monospace">pos.posAng</font> feels wrong too. </div><div><br></div><div>Thanks for any advice.</div><div><br></div><div>Kelle</div><div dir="ltr" class="gmail_signature" data-smartmail="gmail_signature"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div><br></div><div>--</div><div>Kelle Cruz, PhD (she/her, they/them)</div><div><div>Assoc. Professor, Physics and Astronomy, Hunter College<br></div><div>CEO, ScienceBetter Consulting, LLC</div><div>CFO, <a href="http://shop.startorialist.com/" target="_blank">Startorialist, Inc.</a></div><div>Editor-in-Chief, <a href="http://astrobetter.com/" target="_blank">AstroBetter Blog and Wiki</a></div><div>Research Associate, American Museum of Natural History</div><div>Visiting Scholar, Flatiron Institute<br></div></div></div></div></div></div></div></div>
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