<html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class=""><div class="">Hi All, I just read this thread, so first thing first: Thanks a lot <b class="">Markus</b>, this is a very good idea.</div><div class=""><br class=""></div><div class="">4 things:</div><div class=""><br class=""></div><div class="">1.- I’d like to reassure that “<b class="">measurements</b>” is used in ObsCore, at least at ESO, where currently:</div><div class=""><br class=""></div><div class="">SELECT count(*) qty, dataproduct_type</div><div class="">FROM ivoa.obscore</div><div class="">GROUP BY dataproduct_type</div><div class=""><br class=""></div><div class=""><pre class=""> qty |dataproduct_type
-------|----------------
12673 |"cube"
542500 |"image"
391754 |"measurements"
1769243|"spectrum"
2562 |"visibility" </pre><div class=""><br class=""></div></div><div class="">(maybe, Markus, your query was for “measurement” without the ending “s” ?)</div><div class=""><br class=""></div><div class=""><div class="">See: </div><div class=""><a href="http://archive.eso.org/programmatic/#TAP?e=4&f=votable&m=200&q=SELECT%20count(*)%20qty%2C%20dataproduct_type%0AFROM%20ivoa.obscore%0AGROUP%20BY%20dataproduct_type&" class="">http://archive.eso.org/programmatic/#TAP?e=4&f=votable&m=200&q=SELECT%20count(*)%20qty%2C%20dataproduct_type%0AFROM%20ivoa.obscore%0AGROUP%20BY%20dataproduct_type&</a></div></div><div class=""><br class=""></div><div class=""><br class=""></div><div class="">2.- Our <b class="">measurements</b> products are FITS binary tables <b class="">of 3 subtypes</b>: </div><div class="">
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<div class="column"><p class=""><font face="ArialMT" class=""><span style="font-size: 9pt;" class="">- <b class="">catalog</b>: scientific catalogue (typically all-sky) in single FITS binary table </span></font><span style="font-family: ArialMT; font-size: 9pt;" class="">(26 such catalogs)</span></p><p class=""><font face="ArialMT" class=""><span style="font-size: 9pt;" class="">e.g. the catalog of PESSTO transients, the GAIA-ESO catalog containing radial velocities, </span>metallicities, effective temperatures, etc of about<span style="font-size: 9pt;" class=""> 25000 stars, the </span></font><span style="white-space: pre-wrap;" class="">Next Generation Transit Survey source catalogue (204,000 records), etc.</span></p><div class="">- <b class="">catalogtile</b>: one FITS binary table for each of the tiles an ESO Public Survey (or other observing programmes) is partitioned into </div><div class=""><span style="font-family: ArialMT; font-size: 9pt;" class=""> (22,502 such catalog tiles)</span></div><div class=""><span style="font-family: ArialMT; font-size: 9pt;" class=""><br class=""></span></div><div class="page" title="Page 13"><div class="section"><div class="layoutArea"><div class="column"><div class="">- <b class="">srctbl</b>: source tables derived from individual images (~370,000 such srctbl)</div><div class=""><br class=""></div><div class="">The distinction between the three subtypes is conveyed by the dataproduct_subtype field.</div><div class=""><br class=""></div><div class="">Catalogs are exposed both:</div><div class=""><br class=""></div><div class="">- as FITS binary tables individually downloadable, </div><div class=""><br class=""></div><div class="">- by the record, via a dedicated TAP interface to query the content of those tables,</div><div class=""> currently totalling 40 billion records, mostly from catalog tiles.</div><div class=""><br class=""></div><div class="">Source tables are only exposed as FITS binary tables.</div><div class=""> </div><div class=""><br class=""></div><div class="">3- I want to stress that we make a <b class="">distinction</b> <b class="">between</b> “<b class="">sources</b>” <b class="">and</b> physical “<b class="">objects</b>"</div><div class=""><br class=""></div><div class=""><b class="">sources</b>: are <b class="">detections</b> on single images (single bands). It is not given that a detection is for a real object, it could be just only a spurious detection. In this sense, sources are not yet objects, unless they get confirmed into “objects" by the analysis process (see physical objects)</div><div class=""><br class=""></div><div class="">physical <b class="">objects</b>, e.g.:</div><div class="">- objects in catalog tiles: sources in different images (e.g. in multiple wavelength bands) recognised to be detections of the same object (cross-correlation implied)</div><div class="">- objects in all-sky catalogs: whereby typically the measurements are derived from 1 or multiple spectra of the same object</div><div class=""><br class=""></div><div class="">Objects end up in “catalogs”, while sources remain in “source tables”. </div><div class=""><br class=""></div><div class="">From the above you can immediately understand that I fully second<b class=""> Laurent: </b></div><div class=""><b class="">A catalog can be derived from many source tables </b>(e.g. via cross-correlation of source tables in different bands)<b class="">.</b></div><div class=""><br class=""></div><div class=""><br class=""></div><div class="">4- <b class="">multi-typed catalogs</b>: some all-sky catalogs (e.g. the <span style="white-space: pre-wrap;" class="">PESSTO multi-epoch and multi-band photometry) are actually </span><b style="white-space: pre-wrap;" class="">time series of SEDs</b><span style="white-space: pre-wrap;" class="">, (I should probably change the subtype to SED to make it discoverable), while others are simpler (e.g. NGTS) </span><span style="white-space: pre-wrap;" class="">light curves, </span><span style="white-space: pre-wrap;" class="">ie</span><span style="white-space: pre-wrap;" class=""> time series of photometric points in one single band</span><span style="white-space: pre-wrap;" class=""> (that’s where the bulk of the 40 billion records (31E9) come from).</span></div><div class=""><span style="white-space: pre-wrap;" class=""><br class=""></span></div><div class=""><span style="white-space: pre-wrap;" class="">The PESSTO example shows that indeed <b class="">we need to combine various types</b>, as <b class="">Baptiste</b> was already indicating.</span></div><div class=""><br class=""></div><div class=""><span style="white-space: pre-wrap;" class="">Thanks and cheers,</span></div><div class=""><span style="white-space: pre-wrap;" class="">Alberto</span></div><div class=""><br class=""></div><div class=""><br class=""></div></div></div></div></div><p class=""><span style="font-size: 9.000000pt; font-family: 'ArialMT'" class=""><br class=""></span></p><p class=""><span style="font-size: 9.000000pt; font-family: 'ArialMT'" class=""> </span></p>
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