<div dir="ltr"><div dir="ltr"><br></div><div class="gmail_quote"><div dir="ltr">On Sat, Dec 22, 2018 at 1:40 PM Arnold Rots <<a href="mailto:arots@cfa.harvard.edu">arots@cfa.harvard.edu</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-style:solid;border-left-color:rgb(204,204,204);padding-left:1ex"><div dir="ltr">
<div> if so, is it always EQUATORIAL?<br></div><div>Usually, but I don't think it needs to be, necessarily; could be converted to Galactic, for instance<br></div><div>Caveat: it can be either specified by separate RA and Dec components, or as total PM and a direction (CCW from North)<br></div><div><br></div></div></blockquote><div><br></div><div>You mean a speed + direction given as an angle CCW from the +Dec direction? (or +b if in Galactic)</div><div> <br></div></div></div>