<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;"><div dir="auto" style="overflow-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;">Hi Markus,<div><br></div><div>See inline comments below.<br id="lineBreakAtBeginningOfMessage"><div><br><blockquote type="cite"><div>On Apr 25, 2025, at 03:29, Markus Demleitner via heig <heig@ivoa.net> wrote:</div><br class="Apple-interchange-newline"><div><div>Dear Mireille,<br><br>Thanks for your VEP.<br><br>On Thu, Apr 24, 2025 at 06:16:36PM +0200, Mireille Louys via semantics wrote:<br><blockquote type="cite">• Proposedefinitionsforaproduct-type *event-bundle:* An event-bundledataset<br>is a complex object containing an event-list and multiple files or<br>other substructures that are products necessary to analyse the event-list.<br>Data in an event-bundle may thus be used to produce higher leveldata<br>products such as images or spectra.<br></blockquote><br>I think the definition is reasonably clear and applicable in<br>practice. Before merging this, however, I'd have a few requests for<br>clarification:<br><br>(1) used-in: I really, *really* would like to see actual, published<br>data here (always, in all VEPs; it's a pain if we go into all the<br>trouble of defining a concept and then nobody's ever using it in<br>practice). I see that CSC on https://www.google.com/url?q=http://cda.cfa.harvard.edu/csctap&source=gmail-imap&ust=1746354088000000&usg=AOvVaw0j-MeVn0RHNoz8KtLXi1tH (or<br>https://www.google.com/url?q=http://cda.cfa.harvard.edu/csc21tap&source=gmail-imap&ust=1746354088000000&usg=AOvVaw3xeGe6fO6Vz7vemy8dYWD2 [1]) has an obscore table. It<br>would really be excellent if they could mark up their event bundles<br>with the new term, such that we could say:<br><br> used-in: dataset ivo://csc.harvard.edu/scsr2?some-obs-id on https://www.google.com/url?q=http://cda.cfa.harvard.edu/csctap&source=gmail-imap&ust=1746354088000000&usg=AOvVaw0j-MeVn0RHNoz8KtLXi1tH<br><br>That would help me maintain a clear consciousness when setting up the<br>new term[2].<br></div></div></blockquote><div><br></div><div>I’m not sure that we would use event bundles for any of the CSC data product types, since our catalog users generally want to discover and retrieve individual data products (typically, many of the same data product such as a light curve or aperture photometry MPDF for a set of sources, such as all high redshift quasars).</div><div><br></div><div>We do make event bundles available through the Chandra Data Archive (CDA) ObsCore for individual observations, but we have been doing this for many years and therefore those bundles do not conform to the proposed ObsCore HE extension. For example, at <a href="https://cda.harvard.edu/cxctap">https://cda.harvard.edu/cxctap</a> one might do a query like</div><div>SELECT TOP 100</div><div> *</div><div>FROM ivoa.ObsCore</div><div>WHERE obs_id='22830'</div><div><br></div><div>The bundles currently have dataproduct_type = ‘’ and correspond to the Chandra “primary” and “primary” + “secondary” data product categories for the observation. The “primary” package includes a basic set of data products that an observer would need to analyze the observation and produce photometrically calibrated spectra, while the “secondary” set would be needed in addition if the user wanted to recalibrate the observation with updated calibrations (which we recommend because some updated calibrations only become available typically several months after an observation is completed as calibrations such as detector gain change with time). The bundles are tarballs and have access_format “application/x-tar”.</div><div><br></div><div>Note that our bundles do not include responses, unlike (e.g.) CTAO. This is partly because the spacecraft dithers on the sky during an observation so any target moves across the detector during the observation. So the responses depend critically on the user’s choice of data filtering. We follow the HEASARC standards and provide separate RMF and ARF data products rather than a combined IRF. For spectral fitting, the integrated ARF (i.e., the effective area integrated over an energy range) also depends on the source spectral model, so we provide tools for the user to compute the responses and the data products needed to do so in the “primary” bundle. See <a href="https://cxc.harvard.edu/cda/DataProdList.html#A">https://cxc.harvard.edu/cda/DataProdList.html#A</a> for the list of Chandra primary and secondary products.</div><div><br></div><br><blockquote type="cite"><div><div><br>(2) Relationship: That's an operational field, i.e., I need to create<br>an RDF triple from this. The question thus is: is #event-list wider<br>than #event-bundle or is it the other way round? I could conjure up<br>arguments for both, so, as usual, I'd approach the question from the<br>user side: If I'm looking for #event-bundle, do I want to see<br>#event-list, too? If I'm looking for #event-list, do I want to see<br>#event-bundle, too? Whatever ought to encompass the other is the<br>wider term.<br></div></div></blockquote><div><br></div><div>I would guess probably not, but maybe. I think an event bundle will always include the event list, so if you are asking for an event bundle then the event list would be redundant. Note that an event bundle could really be a physical bundle such as a tar file (as is the case for Chandra) or perhaps all the products are accessed via DataLink. If somebody asks for an event list, they probably just want the event list but perhaps they don’t know about event bundles and therefore might like to see both. There are definitely cases where they really do want just the event list - for example, a lot of folks are interested only in morphological studies and, especially if they want all observations of an object or class of object, bundles may add a lot of extra unwanted data volume. Would it hurt to see them? Well if your query returns 500 event lists and also 500 bundles it just muddies the waters. For users of advanced data products (e.g., Chandra Source Catalog products) I suspect that bundles would likely never be desired (and as I said above, I don’t think we would provide them).</div><div><br></div><div>Conversely, some folks may only want responses and not the associated event lists. At the catalog level for example, we have lots of folks who just want to download point spread functions. Why? The Chandra PSF varies strongly (~factor of 50) across the field of view (with off-axis angle and azimuthal angle) and also with energy. We actually archive the local PSF for every catalog detection at several energies, and with ~50,000 counts. So we effectively have a library of (currently) ~1.3 million Chandra PSFs at several energies that are catalog advanced data products and may save users from having to create their own PSFs.</div><div><br></div><div>A lot of our actual catalog usage cases start with users querying the catalog, then refining their sample and retrieving a subset of catalog data products (likely including event lists), then retrieving additional data products such as light curves, spectra, or aperture photometry products as they work through their analyses. These products are not part of bundles, but we find this usage pattern of wanting to retrieve additional products in stages to be quite common for folks who are doing archival science (vs. those who are retrieving their own observation data).</div><div><br></div><br><blockquote type="cite"><div><div><br>(3) Rationale: If the answer to both of the two questions in the<br>preceding paragraph is "Yes", then it turns out the concepts are<br>identical (A ⊂ B and B ⊂ A implies A = B), and hence you really don't<br>want a new concept but augement #event-list to be something like,<br>say, "Event list, possibly augmented with ancillary information".<br>This points to an issue with your rationale: It basically argues that<br>there's something you would like to say.<br><br>An aphorism I'm bringing up rather often these days is: "In protocol<br>design, don't think about what you want to say. Think about what<br>others want to listen to." Hence, it's be really great if the<br>rationale said why someone would want to look for #event-bundle<br>*rather than* #event-list (or for #event-list rather than<br>#event-bundle, if the the former is the narrower term). Could you<br>provide that information in the Rationale section?<br><br>Thanks,<br><br> Markus<br><br><br>[1] Regrettably, the CSC TAP services seem to be mildly broken at the<br>moment. Coming in with http, they issue https redirects which<br>confuse TOPCAT; CXC folks: if you really need the forced redirects<br>(see<br><https://www.google.com/url?q=https://blog.tfiu.de/foced-https-redirects-considered-harmful.html&source=gmail-imap&ust=1746354088000000&usg=AOvVaw2y6JI9YuzGb_dp9cgELJym> for<br>a better alternative) then please update your registry records to<br>point to the https URIs. Even with https, however, I'm getting a<br>"cscrel2.dbo.obscore not found" error from TOPCAT when running<br><br> select top 30 * from ivoa.obscore where dataproduct_type='event-list'<br><br>It would be great if you could fix that (and a regular run of stilts<br>taplint is good practice anyway)<br></div></div></blockquote><div><br></div>The https to http redirects is a known issue and should be fixed in the next full data system release, which is scheduled for mid-June.</div><div><br></div><div>We’ll look into the other issue you reported.</div><div><br></div><div><br><blockquote type="cite"><div><div><br>[2] You see,<br><https://www.google.com/url?q=https://ivoa.net/documents/Vocabularies/20230206/REC-Vocabularies-2.1.html%23tth_sEcC.2&source=gmail-imap&ust=1746354088000000&usg=AOvVaw0vPm8jxoQ6ePuvFWnKr6ez>,<br>while not exactly normative, is clear on:<br><br> In particular, ensure [...] resources mentioned in Used-in can be<br> reached and reflect the proposed term [...]<br><br>-- <br>heig mailing list<br>heig@ivoa.net<br>https://www.google.com/url?q=http://mail.ivoa.net/mailman/listinfo/heig&source=gmail-imap&ust=1746354088000000&usg=AOvVaw0wTMYFfnqD-UBwfT4NR3kr<br></div></div></blockquote></div><div><br></div><div><br></div>Thanks,<div>—Ian</div><div><br><div>
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