<html><head><meta http-equiv="Content-Type" content="text/html charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class="">Very well, thanks both Markus and Pat.<div class=""><br class=""></div><div class="">So, yes, we need a v_resolution, and it must be in fixed units.</div><div class="">Taking the Greisen et al. default, this is [m/s].</div><div class=""><br class=""></div><div class="">We though need the fravergy UCD to be able to discriminate the different velocity flavours.</div><div class="">Is em_ucd the correct field to use? </div><div class="">(Yes, I’m hit strongly by the confusion of throwing untested features from a data model into a relational mapping,</div><div class="">that’s why I need your confirmation on this)</div><div class=""><br class=""></div><div class="">Thanks!</div><div class="">Alberto</div><div class=""><br class=""></div><div class=""><br class=""></div><div class=""><div class=""><div><blockquote type="cite" class=""><div class="">On 21 Feb 2023, at 21:11, Alberto Micol <<a href="mailto:amicol@eso.org" class="">amicol@eso.org</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div class="WordSection1" style="page: WordSection1; font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px;"><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 10.5pt; font-family: Helvetica;" class="">Hi James,</span><span style="font-size: 11pt;" class=""><o:p class=""></o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 10.5pt; font-family: Helvetica;" class=""><o:p class=""> </o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 10.5pt; font-family: Helvetica;" class="">Thanks for the answer. I have a question/doubt regarding the v_resolution and v_unit.<o:p class=""></o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 10.5pt; font-family: Helvetica;" class=""><o:p class=""> </o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 10.5pt; font-family: Helvetica;" class="">ObsCore already foresees the em_resolution, so I originally thought we do not need the v_resolution.<o:p class=""></o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 10.5pt; font-family: Helvetica;" class=""><o:p class=""> </o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 10.5pt; font-family: Helvetica;" class="">But now I am reconsidering this, because I think (in the ObsCore standard we were not super-clear regarding this) the units of em_resolution are the ones provided by the em_unit attribute. Different cubes could have different em_units, and that means that em_resolution could not be used to seamlessly query across all possible cubes.<o:p class=""></o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 10.5pt; font-family: Helvetica;" class=""><o:p class=""> </o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 10.5pt; font-family: Helvetica;" class="">If the above is correct, then, yes, we need to have a new field,<o:p class=""></o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 10.5pt; font-family: Helvetica;" class="">v_resolution, with units fixed to e.g. m/s,<o:p class=""></o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 10.5pt; font-family: Helvetica;" class="">similarly to the case of em_min/max always provided in [m], whatever the value of the em_unit, to support searches.<o:p class=""></o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 10.5pt; font-family: Helvetica;" class=""><o:p class=""> </o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 10.5pt; font-family: Helvetica;" class="">In which case, we do not need a v_unit, as v_min/max are fixed in [m/s] and we already have em_unit for the units encoded in the cube.<o:p class=""></o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 10.5pt; font-family: Helvetica;" class=""><o:p class=""> </o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 10.5pt; font-family: Helvetica;" class="">Would that make sense?<o:p class=""></o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 10.5pt; font-family: Helvetica;" class=""><o:p class=""> </o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 10.5pt; font-family: Helvetica;" class="">Regarding treating frequency cubes as velocity cubes (and viceversa), <o:p class=""></o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 10.5pt; font-family: Helvetica;" class="">it is indeed useful to provide characterisations both in frequency and in velocity<o:p class=""></o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 10.5pt; font-family: Helvetica;" class="">(and why not energy and wavelength), distinguishing the different cases according to<o:p class=""></o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 10.5pt; font-family: Helvetica;" class="">the value of the em_ucd, e.g., em.freq, em.wl, em.energy (see ObsCore B.6.2), or<o:p class=""></o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 10.5pt; font-family: Helvetica;" class="">spect.dopplerVeloc.radio, spect.dopplerVeloc.opt, spect.dopplerVeloc.rel (*) (see ObsCore B.6.2.6). <o:p class=""></o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 10.5pt; font-family: Helvetica;" class=""><o:p class=""> </o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 10.5pt; font-family: Helvetica;" class="">So we would have:<o:p class=""></o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 10.5pt; font-family: Helvetica;" class=""><o:p class=""> </o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 10.5pt; font-family: Helvetica;" class="">em_ucd required<o:p class=""></o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 10.5pt; font-family: Helvetica;" class="">v_resolution required, fixed in m/s<o:p class=""></o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 10.5pt; font-family: Helvetica;" class="">em_unit optional, expressing the unit encoded in the cube for the spectral axis<o:p class=""></o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 10.5pt; font-family: Helvetica;" class="">em_resolution optional, expressing the resolution in the units used by the data cube<o:p class=""></o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 10.5pt; font-family: Helvetica;" class=""><o:p class=""> </o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 10.5pt; font-family: Helvetica;" class="">If we converge on this, I could put together a little document with a detailed proposal.<o:p class=""></o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 10.5pt; font-family: Helvetica;" class="">Would that considered useful?<o:p class=""></o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 10.5pt; font-family: Helvetica;" class=""><o:p class=""> </o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 10.5pt; font-family: Helvetica;" class="">Cheers,<o:p class=""></o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 10.5pt; font-family: Helvetica;" class="">Alberto<o:p class=""></o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 10.5pt; font-family: Helvetica;" class=""><o:p class=""> </o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 10.5pt; font-family: Helvetica;" class="">(*) cross-standard issue: the spect.dopplerVeloc.rel is mentioned in the ObsCore standard, <o:p class=""></o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 10.5pt; font-family: Helvetica;" class="">but it is not a recognised value in the current UCD1+ standard.<o:p class=""></o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 10.5pt; font-family: Helvetica;" class="">We will need to act on this (Mireille?).<o:p class=""></o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class=""><o:p class=""> </o:p></span></div><div style="border-style: solid none none; border-top-width: 1pt; border-top-color: rgb(181, 196, 223); padding: 3pt 0cm 0cm;" class=""><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><b class=""><span style="font-size: 12pt;" class="">From:<span class="Apple-converted-space"> </span></span></b><span style="font-size: 12pt;" class="">"Dempsey, James (IM&T, Black Mountain)" <<a href="mailto:James.Dempsey@csiro.au" style="color: purple; text-decoration: underline;" class="">James.Dempsey@csiro.au</a>><br class=""><b class="">Date:<span class="Apple-converted-space"> </span></b>Thursday, 16 February 2023 at 00:21<br class=""><b class="">To:<span class="Apple-converted-space"> </span></b>Alberto Micol <<a href="mailto:amicol@eso.org" style="color: purple; text-decoration: underline;" class="">amicol@eso.org</a>>, "<a href="mailto:dal@ivoa.net" style="color: purple; text-decoration: underline;" class="">dal@ivoa.net</a>" <<a href="mailto:dal@ivoa.net" style="color: purple; text-decoration: underline;" class="">dal@ivoa.net</a>><br class=""><b class="">Subject:<span class="Apple-converted-space"> </span></b>Re: ObsCore for velocity cubes<o:p class=""></o:p></span></div></div><div class=""><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class=""><o:p class=""> </o:p></span></div></div><table class="MsoNormalTable" border="0" cellspacing="0" cellpadding="0" width="100%" style="width: 356px;"><tbody class=""><tr class=""><td style="border-width: 1pt 1pt 1pt 6pt; border-style: solid; border-color: orange; background-color: white; padding: 7.5pt; background-position: initial initial; background-repeat: initial initial;" class=""><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-family: Arial, sans-serif;" class="">This email was sent from outside of ESO from the address<strong class=""><span style="font-family: Arial, sans-serif;" class="">[<a href="mailto:prvs=40330730a=James.Dempsey@csiro.au" style="color: purple; text-decoration: underline;" class="">prvs=40330730a=James.Dempsey@csiro.au</a>]</span></strong><span style="" class="">. If it looks suspicious, please report it to<span class="Apple-converted-space"> </span><a href="mailto:phishing@eso.org" style="color: purple; text-decoration: underline;" class="">phishing@eso.org</a>.</span><o:p class=""></o:p></span></div></td></tr></tbody></table><p class="MsoNormal" style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;"></p><table class="MsoNormalTable" border="0" cellspacing="0" cellpadding="0"><tbody class=""><tr style="height: 7.5pt;" class=""><td width="100%" style="width: 2.78125px; padding: 0cm; height: 7.5pt;" class=""><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif; line-height: 7.5pt;" class=""><span style="font-size: 7.5pt;" class=""> <o:p class=""></o:p></span></div></td></tr></tbody></table><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt; color: white;" class="">Hi Alberto</span><span style="font-size: 11pt;" class="">,</span><o:p class=""></o:p></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class=""> </span><o:p class=""></o:p></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class="">At CASDA we support cutouts of velocity spectral line cubes.</span><o:p class=""></o:p></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class=""> </span><o:p class=""></o:p></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class="">We currently require the user to provide a BAND or CHANNEL parameter to the SODA service which is translated by the service to the velocity frame of the target cube. This works, but requiring conversions on both the client and server side isn’t ideal. Likewise, in our ObsCore implementation only the em_ucd indicates the cubes are in velocity but it would certainly be useful to have full velocity information for data discovery!</span><o:p class=""></o:p></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class=""> </span><o:p class=""></o:p></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class="">The extension you outline looks like it would work nicely for the same use case in CASDA. However I think we should add the following to fully describe the velocity axis (as opposed to its translation into wavelength for the base obscore).</span><o:p class=""></o:p></div><ul type="disc" style="margin-bottom: 0cm; margin-top: 0cm;" class=""><li class="MsoListParagraph" style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;"><span style="font-size: 11pt;" class="">v_resolution – value of CDELT3 or CDELT4</span><o:p class=""></o:p></li><li class="MsoListParagraph" style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;"><span style="font-size: 11pt;" class="">v_unit – although this should always be m/s</span><o:p class=""></o:p></li></ul><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class=""> </span><o:p class=""></o:p></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class="">Another consideration is that a lot of our users tend to use velocity to interact with frequency cubes. So even for these frequency cubes we might end up filling in velocity metadata if the fields were defined. Tools such as CARTA tend to automatically show the spectral axis as velocity where it can, such that many users would assume the cubes are in velocity not frequency.</span><o:p class=""></o:p></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class=""> </span><o:p class=""></o:p></div><div class=""><div class=""><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class="">Cheers,</span><o:p class=""></o:p></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><b class=""><span style="font-size: 11pt; color: rgb(0, 169, 206);" class="">James Dempsey</span></b><o:p class=""></o:p></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 9pt;" class="">Senior Developer <span class="Apple-converted-space"> </span></span><span style="font-size: 9pt; color: rgb(0, 169, 206);" class="">|</span><span style="font-size: 9pt;" class=""> CSIRO </span><o:p class=""></o:p></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class=""><a href="mailto:james.dempsey@csiro.au" style="color: purple; text-decoration: underline;" class=""><span style="font-size: 9pt; color: rgb(5, 99, 193);" class="">james.dempsey@csiro.au</span></a></span><span style="font-size: 9pt;" class=""> <span class="Apple-converted-space"> </span></span><span style="font-size: 9pt; color: rgb(0, 169, 206);" class="">|</span><span style="font-size: 9pt;" class=""> 02 6214 2912</span><o:p class=""></o:p></div></div></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class=""> </span><o:p class=""></o:p></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class=""> </span><o:p class=""></o:p></div><div style="border-style: solid none none; border-top-width: 1pt; border-top-color: rgb(181, 196, 223); padding: 3pt 0cm 0cm;" class=""><p class="MsoNormal" style="margin: 0cm 0cm 12pt; font-size: 10pt; font-family: Calibri, sans-serif;"><b class=""><span style="font-size: 12pt;" class="">From:<span class="Apple-converted-space"> </span></span></b><span style="font-size: 12pt;" class="">dal <<a href="mailto:dal-bounces@ivoa.net" class="">dal-bounces@ivoa.net</a>> on behalf of alberto micol <<a href="mailto:amicol.ivoa@googlemail.com" class="">amicol.ivoa@googlemail.com</a>><br class=""><b class="">Date:<span class="Apple-converted-space"> </span></b>Thursday, 16 February 2023 at 12:02 am<br class=""><b class="">To:<span class="Apple-converted-space"> </span></b><a href="mailto:dal@ivoa.net" class="">dal@ivoa.net</a> <<a href="mailto:dal@ivoa.net" class="">dal@ivoa.net</a>><br class=""><b class="">Subject:<span class="Apple-converted-space"> </span></b>ObsCore for velocity cubes</span><o:p class=""></o:p></p></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class="">Dear ObsCorers,</span><o:p class=""></o:p></div><div class=""><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class=""> </span><o:p class=""></o:p></div></div><div class=""><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class="">I have received with much interest the ObsCore extension for RADIO data, thanks for that very clear document.</span><o:p class=""></o:p></div></div><div class=""><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class=""> </span><o:p class=""></o:p></div></div><div class=""><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class="">Would it be possible to have a similar extension for cubes with velocity as third axis (the other two being the usual spatial ones)?</span><o:p class=""></o:p></div></div><div class=""><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class="">Let me call them “velocity cubes”...</span><o:p class=""></o:p></div></div><div class=""><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class=""> </span><o:p class=""></o:p></div></div><div class=""><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class="">Here my use case…</span><o:p class=""></o:p></div></div><div class=""><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class=""> </span><o:p class=""></o:p></div></div><div class=""><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class="">At ESO we need to support cutouts of velocity cubes.</span><o:p class=""></o:p></div></div><div class=""><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class=""> </span><o:p class=""></o:p></div></div><div class=""><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class="">Up to now our SODA interface supported spectra, images, and wavelength cubes;</span><o:p class=""></o:p></div></div><div class=""><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class="">to provide the user with the SODA input parameters and their possible MIN/MAX values</span><o:p class=""></o:p></div></div><div class=""><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class="">we query ivoa.ObsCore.</span><o:p class=""></o:p></div></div><div class=""><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class=""> </span><o:p class=""></o:p></div></div><div class=""><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class="">Now with the introduction of velocity cubes, we would like to get the necessary SODA input params also from ObsCore.</span><o:p class=""></o:p></div></div><div class=""><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class="">We can certainly do so by extending our own ObsCore table (ObsCore allows to extend the table), but I was wondering</span><o:p class=""></o:p></div></div><div class=""><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class="">if others have similar needs, and see if we can agree with a common ObsCore extension.</span><o:p class=""></o:p></div></div><div class=""><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class=""> </span><o:p class=""></o:p></div></div><div class=""><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class="">Velocity cubes should come in a FITS format as described by Greisen et al, 2006, so-called Paper 3.</span><o:p class=""></o:p></div></div><blockquote style="margin: 5pt 0cm 5pt 30pt;" class="" type="cite"><div class=""><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class="">Shortly summarised, the velocity can be either:</span><o:p class=""></o:p></div></div></blockquote><div class=""><ul type="disc" style="margin-bottom: 0cm;" class=""><ul type="circle" style="margin-bottom: 0cm;" class=""><li class="MsoNormal" style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;"><span style="font-size: 11pt;" class="">a radio (VRAD), </span><o:p class=""></o:p></li><li class="MsoNormal" style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;"><span style="font-size: 11pt;" class="">an optical (VOPT), </span><o:p class=""></o:p></li><li class="MsoNormal" style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;"><span style="font-size: 11pt;" class="">a relativistic velocity (ZOPT), </span><o:p class=""></o:p></li><li class="MsoNormal" style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;"><span style="font-size: 11pt;" class="">a generic apparent velocity (VELO).</span><o:p class=""></o:p></li></ul></ul></div><blockquote style="margin: 5pt 0cm 5pt 30pt;" class="" type="cite"><div class=""><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class="">The RESTFRQa (RESTWAVa) keyword conveys the necessary reference frequency (wavelength) to transform velocity into frequency or wavelength. </span><o:p class=""></o:p></div></div><div class=""><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class="">The velocity unit is m/s.</span><o:p class=""></o:p></div></div></blockquote><div class=""><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class=""> </span><o:p class=""></o:p></div></div><div class=""><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class="">SODA cutouts on the velocity axis are usually formulated by passing cuts already expressed in velocity</span><o:p class=""></o:p></div></div><div class=""><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class="">though it must be possible to perform the conversions to and from frequency/wavelength.</span><o:p class=""></o:p></div></div><div class=""><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class=""> </span><o:p class=""></o:p></div></div><div class=""><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class="">What would then be needed in ObsCore is:</span><o:p class=""></o:p></div></div><div class=""><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class=""> </span><o:p class=""></o:p></div></div><div class=""><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class="">v_min</span><o:p class=""></o:p></div></div><div class=""><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class="">v_max</span><o:p class=""></o:p></div></div><div class=""><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class=""> </span><o:p class=""></o:p></div></div><div class=""><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class="">but also, in case of radio velocity cube:</span><o:p class=""></o:p></div></div><div class=""><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class="">f_min</span><o:p class=""></o:p></div></div><div class=""><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class="">f_max (getting these from the RADIO extension)</span><o:p class=""></o:p></div></div><div class=""><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class="">f_rest = RESTFRQ</span><o:p class=""></o:p></div></div><div class=""><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class=""> </span><o:p class=""></o:p></div></div><div class=""><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class="">and, in case of a optical or relativistic velocity cube</span><o:p class=""></o:p></div></div><div class=""><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class="">em_rest = RESTWAV</span><o:p class=""></o:p></div></div><div class=""><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class="">(we already have em_min, em_max)</span><o:p class=""></o:p></div></div><div class=""><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class=""> </span><o:p class=""></o:p></div></div><div class=""><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class="">The em_resolv_power should then be set to:</span><o:p class=""></o:p></div></div><div class=""><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class=""> lambda freq c</span><o:p class=""></o:p></div></div><div class=""><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class=""> ——————— = ————— = —————</span><o:p class=""></o:p></div></div><div class=""><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class=""> delta lambda delta freq 2 * delta_v</span><o:p class=""></o:p></div></div><div class=""><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class=""> </span><o:p class=""></o:p></div></div><div class=""><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class="">where delta_v is the CD3_3 in the cube (in the example of a cube with the velocity on the third axis);</span><o:p class=""></o:p></div></div><div class=""><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class="">but I would also likely accept a v_pixel_scale (= delta_v).</span><o:p class=""></o:p></div></div><div class=""><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class=""> </span><o:p class=""></o:p></div></div><div class=""><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class="">The UCD for the velocity should then be:</span><o:p class=""></o:p></div></div><div class=""><pre style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: 'Courier New';" class="">spect.dopplerVeloc.opt<o:p class=""></o:p></pre><div class=""><pre style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: 'Courier New';" class="">spect.dopplerVeloc.radio<o:p class=""></o:p></pre><div class=""><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class="">unsure what it should be for the relativistic case.</span><o:p class=""></o:p></div></div></div></div><div class=""><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class=""> </span><o:p class=""></o:p></div></div><div class=""><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class="">This would allow us at ESO to implement SODA on top of ObsCore (as already done for all other parameters)</span><o:p class=""></o:p></div></div><div class=""><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class="">and would allow astronomer to search the velocity cubes with certain characteristics using ObsCore.</span><o:p class=""></o:p></div></div><div class=""><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class=""> </span><o:p class=""></o:p></div></div><div class=""><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class="">What do you think? </span><o:p class=""></o:p></div></div><div class=""><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class="">Is that doable? I think at ESO we will simply start implementing the above extra ObsCore parameters (unless you suggest different names for that),</span><o:p class=""></o:p></div></div><div class=""><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class="">while waiting to see if there is more interest to build a proper standard.</span><o:p class=""></o:p></div></div><div class=""><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class=""> </span><o:p class=""></o:p></div></div><div class=""><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class="">Eager to know what you think, </span><o:p class=""></o:p></div></div><div class=""><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class="">Cheers,</span><o:p class=""></o:p></div></div><div class=""><div style="margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class="">Alberto</span></div></div></div></div></blockquote></div><br class=""></div></div></body></html>