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[fitsbits] 'Dataset Identifications' postings (digest)
On 16 Mar 2004, Don Wells wrote a digest :
From: Thomas McGlynn There is an effort underway at several of the NASA archives to provide a standard dataset identifier for data that can be retrieved from the archives. The initial motivation is that when authors publish [...] motivation understood and agreed The keyword 'DS_IDENT' has been suggested. Does anyone have objections to this or do they know of systems that already use this keyword? I believe this or any other unused name is fine ------------------------------------------------------------------------ From: (Rob Seaman) NOAO (through "Save the bits") has three or four million discrete FITS images packaged up into MEF files for purposes of efficient and easy handling. On the other hand, HEASARC's usage supplies an example involving one dataset that contains several files. would the former be "one file 'originally from' many datasets but now actually a new dataset on its own" ? While the latter seems more familiar to me. But I can imagine another case, i.e. data retrieved from a site with a database and containing part of a catalog. Personally, I think before we reserve "DS_IDENT" or any other keyword for the purpose of identifying datasets, we should define the concept of a "dataset". Yes I think so. Let me say what is my *understanding* of a "dataset" (which does not mean it's something I propose as THE definition !) based on some past experiences. In the case of an X-ray satellite, typically one has a unit like an observing proposal [A], which includes one or more pointings. The pointing [b] occurs in a given time interval, and may involve SIMULTANEOUS observations by more than one instrument [C]. For each instrument the overall time may be divided in consecutive time intervals [D] in which a given instrument configuration is used. There may be many different telemetry packet streams generated during each interval [D], roughly speaking many different files ... not even FITS files. At some stage they might be transformed in a group of many different (FITS ?) files, which will be kept together as a dataset. Just to make some examples, for the long forlorn Exosat satellite, the observer was receiving an half-inch tape called a FOT. There was one logical FOT (maybe spanning several volumes) for each [A][b] combination, where [b] was called the Observing Period (OP) and [D] were called "observations". There were many (non-FITS) files for each [C][D] combination, but I would call the FOT itself as "the dataset". I don't remember if they originally had an identifier other than the name of the target and the date. I heard that ESTEC much later had plans to finally re-archive as FITS event lists, however I haven't followed this. For BeppoSAX, I'm the culprit of having forced inheritance of the above naming, with [A][b] being the OP, and [D] observations. BeppoSAX had FOTs (in the form of DAT cassettes with several non-FITS files) and they were identified by the OP (sequential) number. A dataset was definitely "the OP" or "the associated FOT". I would say more "the OP" as ASDC has been archiving for online access also some reprocessed FITS event lists, grouped by OP. For XMM-Newton the naming is different but the concept is similar. Proposals [A] have a numeric prop-id. [b] are called here "observations" and have a 4-digit obs-id. [D] are called "exposures". What they used to give to observers until a while ago was a CD associated to the combination [A][b] ... and in fact the data were labelled with the concatenation of prop-id and obs-id e.g. 0065760201. Now they distribute data online only, but the scheme has ben retained. "The dataset" is the ensemble of all (many!) (FITS) files pertaining to an [A][b]. I note incidentally that, although no tapes are used, the "flat" naming scheme is still used with long horrible file names like P0065760201M1S001EBLSLI0000.FIT. My personal tendency (but I'm an end user and not an archive mantainer in this context) would have been to put part of the information in directory names and not in file names (e.g. for my own BeppoSAX analysis I used to store files as [A']/[B']/[C]/[D].type, and I tend to use shorter names also for my own XMM reduction (while "the dataset" as distributed by ESA contains instead only two directories, one with the semi-raw FITS reformatted data, and the other one with the pipeline products). But that (flat or tree) arrangement leaves unchanged the definition of which files constitute "a dataset". To go back to another old (but simple) example, in the case of the UV satellite IUE, nobody cared about the proposal id [A] or the object [b] when referring to a dataset. The "unit" was one exposure (one spectrum with a given camera = only one camera operative at any time), or "image", which had identifiers [C][D], e.g. SWP11056. The data delivered to the observer was a set of 4-5 files (originally non FITS) for each "image" (one raw image, and the steps and results of a pipeline). In this case I would be inclined to consider this group of files as "the dataset" (irrespective of the fact that more than one, unrelated, could be placed on a tape) I'm not terribly familiar with the way a ground site like ESO manages its archives, but definitely a proposal [A] can refer to many targets [b], and ultimately to units called "OBs" (Observing Blocks) which are split into exposures. Exposures taken at different times may be associated (e.g. for a multi-object spectrograph one can associate the exposure taken with a given mask with the dark or lamp calibration taken later with the same mask), so it's this association I'd call "the dataset". In any case, I've been talking so far of raw, semi-raw or standard-reduced data archived at the original observatory (or other site in charge of archiving) pertaining to a pointing of an object at a given time. More to come below ... ------------------------------------------------------------------------ From: Jonathan McDowell suppose I have run a modelling tool to get the best deconvolved image fit simultaneously to ROSAT and CHandra data, and stored the result in the FITS file. [...] However, I would say to Thierry that the new file should indeed have a brand new dataset identifier - you have in this case created a new dataset. The traceability to the original observations should be done This is indeed a new case. In general I'm inclined to consider the result of any analysis (as opposed to plain "reduction") to be "private" data. One may keep them, but privately. What matters are the numbers in the published paper. But there might be cases indeed in which such data could be stored and made publicly available (forever ?) although not in a mission archive. OK, they are "a new dataset" but who names them ? Are we going to run into things like "official naming authorities", like the awful "certificates" and "self signed certificates" stuff ? Should we just delegate it to the journals and/or use the bibcode (somebody said something like that) ? There is at least one other different case, databases and catalogues. E.g. I'm managing the database for the XMM-LSS survey (which is a survey done *with* XMM by a consortium using some GO time, but not *by* the XMM ESA project staff, hence "unofficial"). Our collaboration members (and later the public) can export catalogue subsets as FITS files. So far I've not worried about "dataset identification". Of course each RECORD in one of my tables which refer to the XMM data is associated to an XMM pointing (and its propid-obsid), but I'm not keeping this info explicit. And there are other tables containing non X-ray data taken by us (with an optical telescope or with the VLA). There are tables which are authorized subsets of data taken by other consortia. There are tables which are pointers to NED or SIMBAD. Should I really worry here about traceability ? Or just say that the dataset is the XMM-LSS project (an ORIGIN keyword would be enough !) ? ---------------------------------------------------------------------------- Lucio Chiappetti - IASF/CNR - via Bassini 15 - I-20133 Milano (Italy) ---------------------------------------------------------------------------- L'Italia ripudia la guerra [...] come Italy repudiates war {...] as a mezzo di risoluzione delle controversie way of resolution of international internazionali controversies [Art. 11 Constitution of the Italian Republic] ---------------------------------------------------------------------------- For more info : http://www.mi.iasf.cnr.it/~lucio/personal.html ---------------------------------------------------------------------------- |
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[fitsbits] 'Dataset Identifications' postings (digest)
It may be good to clarify the context and scope of what Tom is
proposing (at least my take on it; I won't claim to speak for Tom). The proposal is to introduce the DS_IDENT keyword as a convention for dataset identifiers and to define one particular set of values for this keyword - the ones under the autority of the ADS, i.e., identifier values starting with "ADS/". Anybody who wants to participate in the use of this convention is free to do so, but will have to comply with the the rules of that convention, which a 1. the identifier is of the form "ADS/observatory#dataset" 2. observatory must be taken from the list maintained by the ADS 3. dataset values are controlled by the data center or observatory that bears responsibility for the observatory archive 4. that controlling authority, and its successors and assigns, must guarantee access to dataset in perpetuity 5. the keeper of the observatory data will provide a specific set of services that allow identifier verification, harvesting, and access to the datasets If someone else wants to define another class of identifiers (i.e., other than the "ADS/" class), that is fine, but it would probably be sensible to make sure that the values and useage comply with IVOA standards (as the ADS ones do) in order to maximize usefulness and recognition. I can tell what they, most likely, will look like for Chandra. There will be (at least) three groups: ADS/Sa.CXO#obs/ObsId Points to a particular observation ADS/Sa.CXO#defset/name Points to a specifically defined set of observations ADS/Sa.CXO#bibcode/bibcode Points to all information we have for a particular paper Of course, this begs two questions: - Can two files have the same DS_IDENT value? The answer should be yes, since a dataset may consist of more than one file. - Can one file belong to more than one dataset? The answer is again yes. This may mean that we should allow for DS_IDn keywords. (I said "files"; you may read "extensions", if you like) The question has come up in which headers the keyword should appear. I would recommend putting it in any and all headers where it is appropriate - primary and secondary. Hope this helps, - Arnold Don Wells wrote: ... From: Thomas McGlynn Subject: [fitsbits] Dataset identifications. Newsgroups: sci.astro.fits Date: Wed, 10 Mar 2004 14:20:18 -0500 Organization: NASA Goddard Space Flight Center Reply-To: There is an effort underway at several of the NASA archives to provide a standard dataset identifier for data that can be retrieved from the archives. The initial motivation is that when authors publish a paper they will be able to specify the data that was used in analysis and systems like the ADS will be able to provide links to these data in a systematic way from the papers (and vice versa for the archives). Currently this is done for a few datasets but it's a very manual and labor intensive process. Although the initial impetus is coming from some of the NASA sites, we've been talking with the VO efforts and hope that the ID will be of general utility. I've no doubt that if ID's become established they will be used in many different ways. There are discussions still ongoing as to the exact format to be used. It is intended that the overall format will be compatible with the identification standards that are being discussed in the Virtual Observatory world. An example ID might be ADS/Sa.ROSAT#X/rh701576n00 where the ADS indicates the the ADS will provide the high level resolution service, the 'Sa.ROSAT' is an observatory identifier, and the element that follows the # is observatory specific, but should be familiar enough for those who have used ROSAT data. The question for this group is not so much a discussion of the format of the ID. Rather it was pointed out that if these IDs are successful it would be useful to be able to have a standard FITS keyword that would indicate the dataset id that the current file belongs to. The keyword 'DS_IDENT' has been suggested. Does anyone have objections to this or do they know of systems that already use this keyword? Googling DS_IDENT returns an album of Donna Summer's but no FITS references. Also, are there any issues the we need to resolve regarding the usage of the keyword? One that comes to mind is whether use of this keyword should be recommended only for the primary header of a FITS file. If not then a file may not be associated with a unique dataset id. I'd appreciate any comments, questions or thoughts on the subject. Thanks, Tom McGlynn HEASARC ... -- Donald C. Wells Scientist http://www.cv.nrao.edu/~dwells National Radio Astronomy Observatory +1-434-296-0277 520 Edgemont Road, Charlottesville, Virginia 22903-2475 USA _______________________________________________ fitsbits mailing list http://listmgr.cv.nrao.edu/mailman/listinfo/fitsbits -------------------------------------------------------------------------- Arnold H. Rots Chandra X-ray Science Center Smithsonian Astrophysical Observatory tel: +1 617 496 7701 60 Garden Street, MS 67 fax: +1 617 495 7356 Cambridge, MA 02138 USA http://hea-www.harvard.edu/~arots/ -------------------------------------------------------------------------- |
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[fitsbits] 'Dataset Identifications' postings (digest)
On Tue, 23 Mar 2004, Arnold Rots wrote:
The proposal is to introduce the DS_IDENT keyword as a convention for dataset identifiers and to define one particular set of values for this keyword - the ones under the autority of the ADS, i.e., what does it make them "under the authority of the ADS" ? A specific agreement between ADS and Observatory archive and/or paper author and/or journal and/or IAU ? 2. observatory must be taken from the list maintained by the ADS 5. the keeper of the observatory data will provide a specific set of services that allow identifier verification, harvesting, and access to the datasets What is an observatory here ? A ground based institution (but in that case won't it be better to have a telescope-instrument identifier ?) OR a satellite OR the OFFICIAL data centre of such satellite data ? This seems to rule out "private" datasets (as I defined in my earlier posting) - which might be good - but what about "catalogue" datasets ? If someone else wants to define another class of identifiers (i.e., other than the "ADS/" class), that is fine, but it would probably be sensible to make sure that the values and useage comply with IVOA standards (as the ADS ones do) in order to maximize usefulness and recognition. what is IVOA ? is this a task for the FITS community (if not maybe we should stop here, or confine the discussion to few FITS specific items), for some other IAU body, or for somebody else ? ADS/Sa.CXO#obs/ObsId Points to a particular observation ADS/Sa.CXO#defset/name Points to a specifically defined set of observations Once again these seem to point to something which can be assigned only by an official data centre. ADS/Sa.CXO#bibcode/bibcode Points to all information we have for a particular paper Who is "we" in the above sentence, and what papers should be concerned ? Any paper published on a journal indexed by the ADS ? and who is storing the relevant data ? ADS, CDS, data centre, author ? Any paper on Chandra assuming that the author sends associated reduced data to the Chandra data centre Any paper published by Chandra data centre staff only ? Of course, this begs two questions: - Can two files have the same DS_IDENT value? - Can one file belong to more than one dataset? Yes, but what about the case of the results of a paper regarding the analysis of some particular observational data ? The original (starting) data will be stored at some data centre, but the result will in general be privately owned by the authors, and do not BELONG TO the original dataset, more they STEM OUT OF the original dataset (parent-child relation) -- ---------------------------------------------------------------------- is a newsreading account used by more persons to avoid unwanted spam. Any mail returning to this address will be rejected. Users can disclose their e-mail address in the article if they wish so. |
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[fitsbits] 'Dataset Identifications' postings (digest)
Maybe it helps to state the practical purpose of the identifiers.
It's put in there to inform users as to what dataset identifier to use if and when they insert such identifiers into their manuscripts. The purpose of that is to facilitate the linkage between the literature and the archived datasets. Those links are currently being maintained by a number of data centers (and the ADS) but it is rather labor-intensive. This mechanism would allow for automatic harvesting. More responses below. - Arnold LC's No-Spam Newsreading account wrote: On Tue, 23 Mar 2004, Arnold Rots wrote: The proposal is to introduce the DS_IDENT keyword as a convention for dataset identifiers and to define one particular set of values for this keyword - the ones under the autority of the ADS, i.e., what does it make them "under the authority of the ADS" ? A specific agreement between ADS and Observatory archive and/or paper author and/or journal and/or IAU ? The fact that they start with "ADS/". It is indeed tied in with an agreement between ADS, data centers, journals, aimed at enabling ADS and data centers to harvest literature-dataset links. 2. observatory must be taken from the list maintained by the ADS 5. the keeper of the observatory data will provide a specific set of services that allow identifier verification, harvesting, and access to the datasets What is an observatory here ? A ground based institution (but in that case won't it be better to have a telescope-instrument identifier ?) OR a satellite OR the OFFICIAL data centre of such satellite data ? You will find the current list at: http://vo.ads.harvard.edu/dv/facilities.txt This seems to rule out "private" datasets (as I defined in my earlier posting) - which might be good - but what about "catalogue" datasets ? At least under this authority ID (ADS). If someone else wants to define another class of identifiers (i.e., other than the "ADS/" class), that is fine, but it would probably be sensible to make sure that the values and useage comply with IVOA standards (as the ADS ones do) in order to maximize usefulness and recognition. what is IVOA ? International Virtual Observatory Alliance is this a task for the FITS community (if not maybe we should stop here, or confine the discussion to few FITS specific items), for some other IAU body, or for somebody else ? No, not really, but it deals with a convention involving a FITS keyword which may have repercussion for future use of this keyword. ADS/Sa.CXO#obs/ObsId Points to a particular observation ADS/Sa.CXO#defset/name Points to a specifically defined set of observations Once again these seem to point to something which can be assigned only by an official data centre. Yes. ADS/Sa.CXO#bibcode/bibcode Points to all information we have for a particular paper Who is "we" in the above sentence, and what papers should be concerned ? CDA Any paper published on a journal indexed by the ADS ? No, the ones for which we know there is a Chandra link (in this example). and who is storing the relevant data ? ADS, CDS, data centre, author ? ADS and us. Any paper on Chandra assuming that the author sends associated reduced data to the Chandra data centre Yes, any paper on Chandra data, but no, not linked to products produced to the author - only the archived datasets produced by CXC (where the author started from, presumably). Any paper published by Chandra data centre staff only ? Of course, this begs two questions: - Can two files have the same DS_IDENT value? - Can one file belong to more than one dataset? Yes, but what about the case of the results of a paper regarding the analysis of some particular observational data ? The original (starting) data will be stored at some data centre, but the result will in general be privately owned by the authors, and do not BELONG TO the original dataset, more they STEM OUT OF the original dataset (parent-child relation) That's correct. -- ---------------------------------------------------------------------- is a newsreading account used by more persons to avoid unwanted spam. Any mail returning to this address will be rejected. Users can disclose their e-mail address in the article if they wish so. _______________________________________________ fitsbits mailing list http://listmgr.cv.nrao.edu/mailman/listinfo/fitsbits -------------------------------------------------------------------------- Arnold H. Rots Chandra X-ray Science Center Smithsonian Astrophysical Observatory tel: +1 617 496 7701 60 Garden Street, MS 67 fax: +1 617 495 7356 Cambridge, MA 02138 USA http://hea-www.harvard.edu/~arots/ -------------------------------------------------------------------------- |
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[fitsbits] 'Dataset Identifications' postings (digest)
Arnold Rots writes:
Maybe it helps to state the practical purpose of the identifiers. It's put in there to inform users as to what dataset identifier to use if and when they insert such identifiers into their manuscripts. Thanks! Yes, that does help. The purpose of that is to facilitate the linkage between the literature and the archived datasets. Those links are currently being maintained by a number of data centers (and the ADS) but it is rather labor-intensive. This mechanism would allow for automatic harvesting. An eminently desirable goal. This causes me to strengthen my recommendation that the reserved keyword name(s) be ADSID and ADSIDnnn. (I imagine a thousand ADS dataset identifiers are sufficient for a particular FITS HDU - are they?) You will find the current list at: http://vo.ads.harvard.edu/dv/facilities.txt A very interesting list. Might I suggest that this list be itself scrubbed and extended as part of this process? There is a lot of confusion about the organizations contained on the list. For instance, here are the overtly NOAO related entries: KPNO.12m Kitt Peak National Observatory/12 meter Telescope KPNO.2.1m Kitt Peak National Observatory/2.1 meter Telescope KPNO.BT Kitt Peak National Observatory/Bok Telescope KPNO.MAYALL Kitt Peak National Observatory/Mayall Telescope KPNO.MDMHT Kitt Peak National Observatory/MDM Hitner Telescope KPNO.MDMMH Kitt Peak National Observatory/MDM HcGraw-Hill Telescope KPNO.MPT Kitt Peak National Observatory/McMath-Pierce Telescope KPNO.SARA Kitt Peak National Observatory/Southeastern Association for Reasearch in Astronomy Telescope KPNO.SWT Kitt Peak National Observatory/Space Watch Telescope KPNO.WIYN Kitt Peak National Observatory/WYIN, Wisconson-Indiana-Yale-NOAO Telescope CTIO.1.5m Cerro Tololo Inter-American Observatory/1.5 meter Telescope CTIO.2MASS Cerro Tololo Inter-American Observatory/2MASS Telescope CTIO.VBT Cerro Tololo Inter-American Observatory/Victor Blanco Telescope CTIO.YALO Cerro Tololo Inter-American Observatory/YALO, Yale-AURA-Lisbon-OU Telescope First, note that the "National Optical Astronomy Observatory" is not mentioned yet NOAO is likely the legal owner of many data products resulting from some of these facilities. Second, note: 1) that data from KPNO.12m is owned (I would think) by *NRAO* (as is the telescope), 2) that data from KPNO.BT and KPNO.SWT is owned by the University of Arizona (or perhaps the state of Arizona), 3) that data from KPNO.MPT is owned by the National Solar Observatory, 4) that data from KPNO.MDMHT and KPNO.MDMMH is owned by whoever owned MDM during the epoch of the observations in question, 5) that data from KPNO.SARA is owned by the SARA consortium, 6) that data from KPNO.WIYN is owned by the WIYN consortium, one member of which is NOAO, 7) that there are two 2MASS telescopes and only one is at CTIO 8) that CTIO.YALO was run by the - you guessed it - YALO consortium and has since ceased operations It is quite likely that I got some of those nuances wrong myself :-) There appears to be a confusion between a ground-based observing site and an observatory - perhaps this is a result of the list being compiled by our friends in the space-based astronomical community? In general an observatory is a political entity, a telescope is a facility, and a site like Kitt Peak is a piece of real estate that may be host multiple facilities from multiple observatories. Depending on the details of contracts or other binding operating agreements, an observatory may "own" the data that result from a particular facility like a telescope, instrument, archive or pipeline - or that ownership may devolve to a specific member of some consortium. In many cases, one imagines that a funding agency or government or perhaps even the "people of the United States of America" may ultimately own a particular data product. So, an example. NOAO operates twin 8Kx8K mosaic wide field imagers at its sites on Kitt Peak in Arizona and on Cerro Tololo in Chile. Depending on the phase of the moon (quite literally :-) the resulting data may be owned by NOAO or by some instrumentalities associated with the University of Wisconsin, Indiana University, Yale University and in the near future perhaps the University of Maryland. Confounded with this question of ownership is the issue of proprietary rights. Time on NOAO facilities is awarded competitively and the successful PIs are rewarded with sole access for some period (typically 18 months). A dataset ID can be a relatively simple beast - perhaps as simple as a data source ID and a serial number. But the full taxonomy of dataset provenance has to support many degrees of freedom. At the very least: Nation Funding agency Observatory Consortium member ("partner") Telescope Instrument Date&Time Proposal ID PI and/or project ID ... The more I listen to myself talk, the more I convince (myself, anyway :-) that a single DS_IDENT keyword is a very poor match to the underlying requirements. Not only might a single file belong to multiple datasets certified by a particular entity (like ADS), but they may belong to multiple other datasets certified by multiple other entities - and more to the point, the design of the certification process will vary from one to the next to the next. In particular, the NOAO Science Archive has been discussing the precise questions of ownership and proprietary access and had already selected a subset of fields along the lines of Observatory (NOAO, WIYN, SOAR, etc.), Partner (NOAO, Wisconsin, Indiana, Yale, Brazil, etc.), Telescope (kp4m, ct4m, wiyn, soar, etc.), Instrument (too many to list), Date&Time, and (most similar to the ADS scheme) the NOAO Proposal ID spanning all these facilities. Whatever we settle on will never fit within the confines of any single keyword. On the other hand, I'd love to *also* include an ADSID tag to even further constrain the provenance. Rob Seaman NOAO Science Data Systems |
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[fitsbits] 'Dataset Identifications' postings (digest)
I think there are two different things that are getting confused
in this E-mail discussion. They are closely related, but I think one is possible to address here, while the other requires a much broader venue than this list can provide. When I initiated this discussion I was asking if we would make sense to reserve a keyword in FITS that would be used to specify an identification of the datasets to which the file or HDU belonged. While there is currently a specific format for that identification being considered by some of us, I don't believe it is necessary to tie the the question of whether we define such a keyword with any specific syntax used. E.g., in FITS today we have keywords ORIGIN, TELESCOP, INSTRUME and OBSERVER where the general semantics of the keyword is specified, but the format is completely undefined (other than that it is a string). It is at that level that I believe we could agree on using DS_IDENT (or any other value or values). So I see the discussion about where such a keyword would go, whether we need a keyword that allows for multiple values (which DS_IDENT would not) as the kind of things we could hope to hash out in a discussion here. My own read on this part of the discussion is that most people would want to see the ID repeated in all relevant HDU's and that there probably needs to be at least an option for the id to be a vector value. The later requirement mandates a shorter keyword (perhaps just DSID). However, I do not think that this is the appropriate forum for discussion of a particular syntax for the value of this keyword. I just don't think we can muster the kind of representation from the scientific community that would be needed. While the ADEC hopes that our IDs will be useful and that others will adopt them, we have no power to force such a change -- though the astronomy journals may have a bit broader influence. So if, for example, NOAO were to adopt a different syntax and style for the dataset IDs, for good and sufficient reasons of their own, then they could use the same keyword or keywords and go ahead on their own. It would be desirable in this case if it was possible to distinguish the different syntaxes used. Regardless I think it would be better to have a standard place to look for the IDs than for software to have to look for a list of keywords and see if there was ADSID or ADECID or NOAOID or NRAOID or CDSID or .... The standard keyword[s] would say where to look and with only a minimal level of collaboration we could make sure our different syntaxes didn't interfere with one another. If a new institution decided to create some new id schema they would know where to put it, and I think the chance that existing software could find and use that ID would be much greater. That said I'm not really disagreeing with Bob that discussion of the syntax of the IDs is necessary. All I'm saying is that I don't think we can come to a conclusion to that discussion here. It's easy enough to continue though, and I've added a couple of more specific comments below. (: Tom Rob Seaman wrote: recommendation that the reserved keyword name(s) be ADSID and ADSIDnnn. (I imagine a thousand ADS dataset identifiers are sufficient for a particular FITS HDU - are they?) The basic idea of the IDs as they have been conceived of by the ADEC is that it allows establishment of individual namespaces. So, if for example NOAO doesn't like the naming scheme that used, it would be straightforward to create a set of noao/... ids that conformed to what would be appropriate for your datasets. A very interesting list. Might I suggest that this list be itself scrubbed and extended as part of this process? There is a lot of confusion about the organizations contained on the list. For instance, here are the overtly NOAO related entries: KPNO.12m Kitt Peak National Observatory/12 meter Telescope KPNO.2.1m Kitt Peak National Observatory/2.1 meter Telescope KPNO.BT Kitt Peak National Observatory/Bok Telescope KPNO.MAYALL Kitt Peak National Observatory/Mayall Telescope KPNO.MDMHT Kitt Peak National Observatory/MDM Hitner Telescope KPNO.MDMMH Kitt Peak National Observatory/MDM HcGraw-Hill Telescope KPNO.MPT Kitt Peak National Observatory/McMath-Pierce Telescope KPNO.SARA Kitt Peak National Observatory/Southeastern Association for Reasearch in Astronomy Telescope KPNO.SWT Kitt Peak National Observatory/Space Watch Telescope KPNO.WIYN Kitt Peak National Observatory/WYIN, Wisconson-Indiana-Yale-NOAO Telescope CTIO.1.5m Cerro Tololo Inter-American Observatory/1.5 meter Telescope CTIO.2MASS Cerro Tololo Inter-American Observatory/2MASS Telescope CTIO.VBT Cerro Tololo Inter-American Observatory/Victor Blanco Telescope CTIO.YALO Cerro Tololo Inter-American Observatory/YALO, Yale-AURA-Lisbon-OU Telescope The syntax that was suggested was observatoryLocation.telescope as the way of identifying datasets in a way that will be most straightforware for users. This list was suggested by someone at ApJ as I recall. There has been some discussion about how and if these should be tied to organizations. One concern with organizational ties is that these ID's are intended to be permanent. So 50 years from it may be irrelevant to users that a particular telescope was for a time run by a given organization, and it's certainly possible that control of a telescope (and its data) will shift from one organization to another over the course of its lifetime. In the NASA world, that's actually quite normal. First, note that the "National Optical Astronomy Observatory" is not mentioned yet NOAO is likely the legal owner of many data products resulting from some of these facilities. Second, note: 1) that data from KPNO.12m is owned (I would think) by *NRAO* (as is the telescope), 2) that data from KPNO.BT and KPNO.SWT is owned by the University of Arizona (or perhaps the state of Arizona), 3) that data from KPNO.MPT is owned by the National Solar Observatory, 4) that data from KPNO.MDMHT and KPNO.MDMMH is owned by whoever owned MDM during the epoch of the observations in question, 5) that data from KPNO.SARA is owned by the SARA consortium, 6) that data from KPNO.WIYN is owned by the WIYN consortium, one member of which is NOAO, 7) that there are two 2MASS telescopes and only one is at CTIO 8) that CTIO.YALO was run by the - you guessed it - YALO consortium and has since ceased operations Right, our thought is that organizations will register as responsible for particular dataset holdings. So, e.g., the YALO consoritium would have registered as responsible for that holding and when it ceased operations whoever has inherited responsibility for the holding (if anyone) could register as the responsible party. Thus the granularity of the datasets holdings needs to be small enough that a single party is likely to be responsible for each. It is quite likely that I got some of those nuances wrong myself :-) There appears to be a confusion between a ground-based observing site and an observatory - perhaps this is a result of the list being compiled by our friends in the space-based astronomical community? No... As I mentioned above we didn't do this. If we had we surely wouldn't have lumped all space observatories together! It may be that rather than KPNO and CTIO they should be KP and CT. That certainly seems reasonable to me. I don't think this list is set in concrete or even particularly old jello. In general an observatory is a political entity, a telescope is a facility, and a site like Kitt Peak is a piece of real estate that may be host multiple facilities from multiple observatories. Depending on the details of contracts or other binding operating agreements, an observatory may "own" the data that result from a particular facility like a telescope, instrument, archive or pipeline - or that ownership may devolve to a specific member of some consortium. In many cases, one imagines that a funding agency or government or perhaps even the "people of the United States of America" may ultimately own a particular data product. So, an example. NOAO operates twin 8Kx8K mosaic wide field imagers at its sites on Kitt Peak in Arizona and on Cerro Tololo in Chile. Depending on the phase of the moon (quite literally :-) the resulting data may be owned by NOAO or by some instrumentalities associated with the University of Wisconsin, Indiana University, Yale University and in the near future perhaps the University of Maryland. Confounded with this question of ownership is the issue of proprietary rights. Time on NOAO facilities is awarded competitively and the successful PIs are rewarded with sole access for some period (typically 18 months). All of these issues are certainly complex, but in some sense they are irrelevant. Either the organizations can work out some agreements about how data are named that can be put into a dataset id, or they can't and it won't happen. I don't think we need to solve every problem to have a useful capability. A dataset ID can be a relatively simple beast - perhaps as simple as a data source ID and a serial number. But the full taxonomy of dataset provenance has to support many degrees of freedom. At the very least: Nation Funding agency Observatory Consortium member ("partner") Telescope Instrument Date&Time Proposal ID PI and/or project ID ... Here I think you are confusing the metadata describing an observation with the 'name' of an observation. Why should an ID have the time? One might choose to use the time in the ID. But there is not reason why it has to be done that way. Why does it need a proposal ID, nation, agency? Again you can choose to put them there, but I see no requirement why the general ID specification needs to include this. We are not trying to use the ID as a way of encapsulating the description of the dataset, just a way to point to it. The more I listen to myself talk, the more I convince (myself, anyway :-) that a single DS_IDENT keyword is a very poor match to the underlying requirements. Not only might a single file belong to multiple datasets certified by a particular entity (like ADS), but they may belong to multiple other datasets certified by multiple other entities - and more to the point, the design of the certification process will vary from one to the next to the next. In particular, the NOAO Science Archive has been discussing the precise questions of ownership and proprietary access and had already selected a subset of fields along the lines of Observatory (NOAO, WIYN, SOAR, etc.), Partner (NOAO, Wisconsin, Indiana, Yale, Brazil, etc.), Telescope (kp4m, ct4m, wiyn, soar, etc.), Instrument (too many to list), Date&Time, and (most similar to the ADS scheme) the NOAO Proposal ID spanning all these facilities. Whatever we settle on will never fit within the confines of any single keyword. On the other hand, I'd love to *also* include an ADSID tag to even further constrain the provenance. Agreeing on metadata fields is great, but I think it's largely orthogonal to the question of whether we want a dataset id somewhere as indeed your last comment suggests. |
#7
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[fitsbits] 'Dataset Identifications' postings (digest)
I think there are two different things that are getting confused
in this E-mail discussion. They are closely related, but I think one is possible to address here, while the other requires a much broader venue than this list can provide. When I initiated this discussion I was asking if we would make sense to reserve a keyword in FITS that would be used to specify an identification of the datasets to which the file or HDU belonged. While there is currently a specific format for that identification being considered by some of us, I don't believe it is necessary to tie the the question of whether we define such a keyword with any specific syntax used. E.g., in FITS today we have keywords ORIGIN, TELESCOP, INSTRUME and OBSERVER where the general semantics of the keyword is specified, but the format is completely undefined (other than that it is a string). It is at that level that I believe we could agree on using DS_IDENT (or any other value or values). So I see the discussion about where such a keyword would go, whether we need a keyword that allows for multiple values (which DS_IDENT would not) as the kind of things we could hope to hash out in a discussion here. My own read on this part of the discussion is that most people would want to see the ID repeated in all relevant HDU's and that there probably needs to be at least an option for the id to be a vector value. The later requirement mandates a shorter keyword (perhaps just DSID). However, I do not think that this is the appropriate forum for discussion of a particular syntax for the value of this keyword. I just don't think we can muster the kind of representation from the scientific community that would be needed. While the ADEC hopes that our IDs will be useful and that others will adopt them, we have no power to force such a change -- though the astronomy journals may have a bit broader influence. So if, for example, NOAO were to adopt a different syntax and style for the dataset IDs, for good and sufficient reasons of their own, then they could use the same keyword or keywords and go ahead on their own. It would be desirable in this case if it was possible to distinguish the different syntaxes used. Regardless I think it would be better to have a standard place to look for the IDs than for software to have to look for a list of keywords and see if there was ADSID or ADECID or NOAOID or NRAOID or CDSID or .... The standard keyword[s] would say where to look and with only a minimal level of collaboration we could make sure our different syntaxes didn't interfere with one another. If a new institution decided to create some new id schema they would know where to put it, and I think the chance that existing software could find and use that ID would be much greater. That said I'm not really disagreeing with Bob that discussion of the syntax of the IDs is necessary. All I'm saying is that I don't think we can come to a conclusion to that discussion here. It's easy enough to continue though, and I've added a couple of more specific comments below. (: Tom Rob Seaman wrote: recommendation that the reserved keyword name(s) be ADSID and ADSIDnnn. (I imagine a thousand ADS dataset identifiers are sufficient for a particular FITS HDU - are they?) The basic idea of the IDs as they have been conceived of by the ADEC is that it allows establishment of individual namespaces. So, if for example NOAO doesn't like the naming scheme that used, it would be straightforward to create a set of noao/... ids that conformed to what would be appropriate for your datasets. A very interesting list. Might I suggest that this list be itself scrubbed and extended as part of this process? There is a lot of confusion about the organizations contained on the list. For instance, here are the overtly NOAO related entries: KPNO.12m Kitt Peak National Observatory/12 meter Telescope KPNO.2.1m Kitt Peak National Observatory/2.1 meter Telescope KPNO.BT Kitt Peak National Observatory/Bok Telescope KPNO.MAYALL Kitt Peak National Observatory/Mayall Telescope KPNO.MDMHT Kitt Peak National Observatory/MDM Hitner Telescope KPNO.MDMMH Kitt Peak National Observatory/MDM HcGraw-Hill Telescope KPNO.MPT Kitt Peak National Observatory/McMath-Pierce Telescope KPNO.SARA Kitt Peak National Observatory/Southeastern Association for Reasearch in Astronomy Telescope KPNO.SWT Kitt Peak National Observatory/Space Watch Telescope KPNO.WIYN Kitt Peak National Observatory/WYIN, Wisconson-Indiana-Yale-NOAO Telescope CTIO.1.5m Cerro Tololo Inter-American Observatory/1.5 meter Telescope CTIO.2MASS Cerro Tololo Inter-American Observatory/2MASS Telescope CTIO.VBT Cerro Tololo Inter-American Observatory/Victor Blanco Telescope CTIO.YALO Cerro Tololo Inter-American Observatory/YALO, Yale-AURA-Lisbon-OU Telescope The syntax that was suggested was observatoryLocation.telescope as the way of identifying datasets in a way that will be most straightforware for users. This list was suggested by someone at ApJ as I recall. There has been some discussion about how and if these should be tied to organizations. One concern with organizational ties is that these ID's are intended to be permanent. So 50 years from it may be irrelevant to users that a particular telescope was for a time run by a given organization, and it's certainly possible that control of a telescope (and its data) will shift from one organization to another over the course of its lifetime. In the NASA world, that's actually quite normal. First, note that the "National Optical Astronomy Observatory" is not mentioned yet NOAO is likely the legal owner of many data products resulting from some of these facilities. Second, note: 1) that data from KPNO.12m is owned (I would think) by *NRAO* (as is the telescope), 2) that data from KPNO.BT and KPNO.SWT is owned by the University of Arizona (or perhaps the state of Arizona), 3) that data from KPNO.MPT is owned by the National Solar Observatory, 4) that data from KPNO.MDMHT and KPNO.MDMMH is owned by whoever owned MDM during the epoch of the observations in question, 5) that data from KPNO.SARA is owned by the SARA consortium, 6) that data from KPNO.WIYN is owned by the WIYN consortium, one member of which is NOAO, 7) that there are two 2MASS telescopes and only one is at CTIO 8) that CTIO.YALO was run by the - you guessed it - YALO consortium and has since ceased operations Right, our thought is that organizations will register as responsible for particular dataset holdings. So, e.g., the YALO consoritium would have registered as responsible for that holding and when it ceased operations whoever has inherited responsibility for the holding (if anyone) could register as the responsible party. Thus the granularity of the datasets holdings needs to be small enough that a single party is likely to be responsible for each. It is quite likely that I got some of those nuances wrong myself :-) There appears to be a confusion between a ground-based observing site and an observatory - perhaps this is a result of the list being compiled by our friends in the space-based astronomical community? No... As I mentioned above we didn't do this. If we had we surely wouldn't have lumped all space observatories together! It may be that rather than KPNO and CTIO they should be KP and CT. That certainly seems reasonable to me. I don't think this list is set in concrete or even particularly old jello. In general an observatory is a political entity, a telescope is a facility, and a site like Kitt Peak is a piece of real estate that may be host multiple facilities from multiple observatories. Depending on the details of contracts or other binding operating agreements, an observatory may "own" the data that result from a particular facility like a telescope, instrument, archive or pipeline - or that ownership may devolve to a specific member of some consortium. In many cases, one imagines that a funding agency or government or perhaps even the "people of the United States of America" may ultimately own a particular data product. So, an example. NOAO operates twin 8Kx8K mosaic wide field imagers at its sites on Kitt Peak in Arizona and on Cerro Tololo in Chile. Depending on the phase of the moon (quite literally :-) the resulting data may be owned by NOAO or by some instrumentalities associated with the University of Wisconsin, Indiana University, Yale University and in the near future perhaps the University of Maryland. Confounded with this question of ownership is the issue of proprietary rights. Time on NOAO facilities is awarded competitively and the successful PIs are rewarded with sole access for some period (typically 18 months). All of these issues are certainly complex, but in some sense they are irrelevant. Either the organizations can work out some agreements about how data are named that can be put into a dataset id, or they can't and it won't happen. I don't think we need to solve every problem to have a useful capability. A dataset ID can be a relatively simple beast - perhaps as simple as a data source ID and a serial number. But the full taxonomy of dataset provenance has to support many degrees of freedom. At the very least: Nation Funding agency Observatory Consortium member ("partner") Telescope Instrument Date&Time Proposal ID PI and/or project ID ... Here I think you are confusing the metadata describing an observation with the 'name' of an observation. Why should an ID have the time? One might choose to use the time in the ID. But there is not reason why it has to be done that way. Why does it need a proposal ID, nation, agency? Again you can choose to put them there, but I see no requirement why the general ID specification needs to include this. We are not trying to use the ID as a way of encapsulating the description of the dataset, just a way to point to it. The more I listen to myself talk, the more I convince (myself, anyway :-) that a single DS_IDENT keyword is a very poor match to the underlying requirements. Not only might a single file belong to multiple datasets certified by a particular entity (like ADS), but they may belong to multiple other datasets certified by multiple other entities - and more to the point, the design of the certification process will vary from one to the next to the next. In particular, the NOAO Science Archive has been discussing the precise questions of ownership and proprietary access and had already selected a subset of fields along the lines of Observatory (NOAO, WIYN, SOAR, etc.), Partner (NOAO, Wisconsin, Indiana, Yale, Brazil, etc.), Telescope (kp4m, ct4m, wiyn, soar, etc.), Instrument (too many to list), Date&Time, and (most similar to the ADS scheme) the NOAO Proposal ID spanning all these facilities. Whatever we settle on will never fit within the confines of any single keyword. On the other hand, I'd love to *also* include an ADSID tag to even further constrain the provenance. Agreeing on metadata fields is great, but I think it's largely orthogonal to the question of whether we want a dataset id somewhere as indeed your last comment suggests. |
#8
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[fitsbits] 'Dataset Identifications' postings (digest)
I think there are two different things that are getting confused
in this E-mail discussion. They are closely related, but I think one is possible to address here, while the other requires a much broader venue than this list can provide. When I initiated this discussion I was asking if we would make sense to reserve a keyword in FITS that would be used to specify an identification of the datasets to which the file or HDU belonged. While there is currently a specific format for that identification being considered by some of us, I don't believe it is necessary to tie the the question of whether we define such a keyword with any specific syntax used. E.g., in FITS today we have keywords ORIGIN, TELESCOP, INSTRUME and OBSERVER where the general semantics of the keyword is specified, but the format is completely undefined (other than that it is a string). It is at that level that I believe we could agree on using DS_IDENT (or any other value or values). So I see the discussion about where such a keyword would go, whether we need a keyword that allows for multiple values (which DS_IDENT would not) as the kind of things we could hope to hash out in a discussion here. My own read on this part of the discussion is that most people would want to see the ID repeated in all relevant HDU's and that there probably needs to be at least an option for the id to be a vector value. The later requirement mandates a shorter keyword (perhaps just DSID). However, I do not think that this is the appropriate forum for discussion of a particular syntax for the value of this keyword. I just don't think we can muster the kind of representation from the scientific community that would be needed. While the ADEC hopes that our IDs will be useful and that others will adopt them, we have no power to force such a change -- though the astronomy journals may have a bit broader influence. So if, for example, NOAO were to adopt a different syntax and style for the dataset IDs, for good and sufficient reasons of their own, then they could use the same keyword or keywords and go ahead on their own. It would be desirable in this case if it was possible to distinguish the different syntaxes used. Regardless I think it would be better to have a standard place to look for the IDs than for software to have to look for a list of keywords and see if there was ADSID or ADECID or NOAOID or NRAOID or CDSID or .... The standard keyword[s] would say where to look and with only a minimal level of collaboration we could make sure our different syntaxes didn't interfere with one another. If a new institution decided to create some new id schema they would know where to put it, and I think the chance that existing software could find and use that ID would be much greater. That said I'm not really disagreeing with Bob that discussion of the syntax of the IDs is necessary. All I'm saying is that I don't think we can come to a conclusion to that discussion here. It's easy enough to continue though, and I've added a couple of more specific comments below. (: Tom Rob Seaman wrote: recommendation that the reserved keyword name(s) be ADSID and ADSIDnnn. (I imagine a thousand ADS dataset identifiers are sufficient for a particular FITS HDU - are they?) The basic idea of the IDs as they have been conceived of by the ADEC is that it allows establishment of individual namespaces. So, if for example NOAO doesn't like the naming scheme that used, it would be straightforward to create a set of noao/... ids that conformed to what would be appropriate for your datasets. A very interesting list. Might I suggest that this list be itself scrubbed and extended as part of this process? There is a lot of confusion about the organizations contained on the list. For instance, here are the overtly NOAO related entries: KPNO.12m Kitt Peak National Observatory/12 meter Telescope KPNO.2.1m Kitt Peak National Observatory/2.1 meter Telescope KPNO.BT Kitt Peak National Observatory/Bok Telescope KPNO.MAYALL Kitt Peak National Observatory/Mayall Telescope KPNO.MDMHT Kitt Peak National Observatory/MDM Hitner Telescope KPNO.MDMMH Kitt Peak National Observatory/MDM HcGraw-Hill Telescope KPNO.MPT Kitt Peak National Observatory/McMath-Pierce Telescope KPNO.SARA Kitt Peak National Observatory/Southeastern Association for Reasearch in Astronomy Telescope KPNO.SWT Kitt Peak National Observatory/Space Watch Telescope KPNO.WIYN Kitt Peak National Observatory/WYIN, Wisconson-Indiana-Yale-NOAO Telescope CTIO.1.5m Cerro Tololo Inter-American Observatory/1.5 meter Telescope CTIO.2MASS Cerro Tololo Inter-American Observatory/2MASS Telescope CTIO.VBT Cerro Tololo Inter-American Observatory/Victor Blanco Telescope CTIO.YALO Cerro Tololo Inter-American Observatory/YALO, Yale-AURA-Lisbon-OU Telescope The syntax that was suggested was observatoryLocation.telescope as the way of identifying datasets in a way that will be most straightforware for users. This list was suggested by someone at ApJ as I recall. There has been some discussion about how and if these should be tied to organizations. One concern with organizational ties is that these ID's are intended to be permanent. So 50 years from it may be irrelevant to users that a particular telescope was for a time run by a given organization, and it's certainly possible that control of a telescope (and its data) will shift from one organization to another over the course of its lifetime. In the NASA world, that's actually quite normal. First, note that the "National Optical Astronomy Observatory" is not mentioned yet NOAO is likely the legal owner of many data products resulting from some of these facilities. Second, note: 1) that data from KPNO.12m is owned (I would think) by *NRAO* (as is the telescope), 2) that data from KPNO.BT and KPNO.SWT is owned by the University of Arizona (or perhaps the state of Arizona), 3) that data from KPNO.MPT is owned by the National Solar Observatory, 4) that data from KPNO.MDMHT and KPNO.MDMMH is owned by whoever owned MDM during the epoch of the observations in question, 5) that data from KPNO.SARA is owned by the SARA consortium, 6) that data from KPNO.WIYN is owned by the WIYN consortium, one member of which is NOAO, 7) that there are two 2MASS telescopes and only one is at CTIO 8) that CTIO.YALO was run by the - you guessed it - YALO consortium and has since ceased operations Right, our thought is that organizations will register as responsible for particular dataset holdings. So, e.g., the YALO consoritium would have registered as responsible for that holding and when it ceased operations whoever has inherited responsibility for the holding (if anyone) could register as the responsible party. Thus the granularity of the datasets holdings needs to be small enough that a single party is likely to be responsible for each. It is quite likely that I got some of those nuances wrong myself :-) There appears to be a confusion between a ground-based observing site and an observatory - perhaps this is a result of the list being compiled by our friends in the space-based astronomical community? No... As I mentioned above we didn't do this. If we had we surely wouldn't have lumped all space observatories together! It may be that rather than KPNO and CTIO they should be KP and CT. That certainly seems reasonable to me. I don't think this list is set in concrete or even particularly old jello. In general an observatory is a political entity, a telescope is a facility, and a site like Kitt Peak is a piece of real estate that may be host multiple facilities from multiple observatories. Depending on the details of contracts or other binding operating agreements, an observatory may "own" the data that result from a particular facility like a telescope, instrument, archive or pipeline - or that ownership may devolve to a specific member of some consortium. In many cases, one imagines that a funding agency or government or perhaps even the "people of the United States of America" may ultimately own a particular data product. So, an example. NOAO operates twin 8Kx8K mosaic wide field imagers at its sites on Kitt Peak in Arizona and on Cerro Tololo in Chile. Depending on the phase of the moon (quite literally :-) the resulting data may be owned by NOAO or by some instrumentalities associated with the University of Wisconsin, Indiana University, Yale University and in the near future perhaps the University of Maryland. Confounded with this question of ownership is the issue of proprietary rights. Time on NOAO facilities is awarded competitively and the successful PIs are rewarded with sole access for some period (typically 18 months). All of these issues are certainly complex, but in some sense they are irrelevant. Either the organizations can work out some agreements about how data are named that can be put into a dataset id, or they can't and it won't happen. I don't think we need to solve every problem to have a useful capability. A dataset ID can be a relatively simple beast - perhaps as simple as a data source ID and a serial number. But the full taxonomy of dataset provenance has to support many degrees of freedom. At the very least: Nation Funding agency Observatory Consortium member ("partner") Telescope Instrument Date&Time Proposal ID PI and/or project ID ... Here I think you are confusing the metadata describing an observation with the 'name' of an observation. Why should an ID have the time? One might choose to use the time in the ID. But there is not reason why it has to be done that way. Why does it need a proposal ID, nation, agency? Again you can choose to put them there, but I see no requirement why the general ID specification needs to include this. We are not trying to use the ID as a way of encapsulating the description of the dataset, just a way to point to it. The more I listen to myself talk, the more I convince (myself, anyway :-) that a single DS_IDENT keyword is a very poor match to the underlying requirements. Not only might a single file belong to multiple datasets certified by a particular entity (like ADS), but they may belong to multiple other datasets certified by multiple other entities - and more to the point, the design of the certification process will vary from one to the next to the next. In particular, the NOAO Science Archive has been discussing the precise questions of ownership and proprietary access and had already selected a subset of fields along the lines of Observatory (NOAO, WIYN, SOAR, etc.), Partner (NOAO, Wisconsin, Indiana, Yale, Brazil, etc.), Telescope (kp4m, ct4m, wiyn, soar, etc.), Instrument (too many to list), Date&Time, and (most similar to the ADS scheme) the NOAO Proposal ID spanning all these facilities. Whatever we settle on will never fit within the confines of any single keyword. On the other hand, I'd love to *also* include an ADSID tag to even further constrain the provenance. Agreeing on metadata fields is great, but I think it's largely orthogonal to the question of whether we want a dataset id somewhere as indeed your last comment suggests. |
#9
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[fitsbits] 'Dataset Identifications' postings (digest)
I think there are two different things that are getting confused
in this E-mail discussion. They are closely related, but I think one is possible to address here, while the other requires a much broader venue than this list can provide. When I initiated this discussion I was asking if we would make sense to reserve a keyword in FITS that would be used to specify an identification of the datasets to which the file or HDU belonged. While there is currently a specific format for that identification being considered by some of us, I don't believe it is necessary to tie the the question of whether we define such a keyword with any specific syntax used. E.g., in FITS today we have keywords ORIGIN, TELESCOP, INSTRUME and OBSERVER where the general semantics of the keyword is specified, but the format is completely undefined (other than that it is a string). It is at that level that I believe we could agree on using DS_IDENT (or any other value or values). So I see the discussion about where such a keyword would go, whether we need a keyword that allows for multiple values (which DS_IDENT would not) as the kind of things we could hope to hash out in a discussion here. My own read on this part of the discussion is that most people would want to see the ID repeated in all relevant HDU's and that there probably needs to be at least an option for the id to be a vector value. The later requirement mandates a shorter keyword (perhaps just DSID). However, I do not think that this is the appropriate forum for discussion of a particular syntax for the value of this keyword. I just don't think we can muster the kind of representation from the scientific community that would be needed. While the ADEC hopes that our IDs will be useful and that others will adopt them, we have no power to force such a change -- though the astronomy journals may have a bit broader influence. So if, for example, NOAO were to adopt a different syntax and style for the dataset IDs, for good and sufficient reasons of their own, then they could use the same keyword or keywords and go ahead on their own. It would be desirable in this case if it was possible to distinguish the different syntaxes used. Regardless I think it would be better to have a standard place to look for the IDs than for software to have to look for a list of keywords and see if there was ADSID or ADECID or NOAOID or NRAOID or CDSID or .... The standard keyword[s] would say where to look and with only a minimal level of collaboration we could make sure our different syntaxes didn't interfere with one another. If a new institution decided to create some new id schema they would know where to put it, and I think the chance that existing software could find and use that ID would be much greater. That said I'm not really disagreeing with Bob that discussion of the syntax of the IDs is necessary. All I'm saying is that I don't think we can come to a conclusion to that discussion here. It's easy enough to continue though, and I've added a couple of more specific comments below. (: Tom Rob Seaman wrote: recommendation that the reserved keyword name(s) be ADSID and ADSIDnnn. (I imagine a thousand ADS dataset identifiers are sufficient for a particular FITS HDU - are they?) The basic idea of the IDs as they have been conceived of by the ADEC is that it allows establishment of individual namespaces. So, if for example NOAO doesn't like the naming scheme that used, it would be straightforward to create a set of noao/... ids that conformed to what would be appropriate for your datasets. A very interesting list. Might I suggest that this list be itself scrubbed and extended as part of this process? There is a lot of confusion about the organizations contained on the list. For instance, here are the overtly NOAO related entries: KPNO.12m Kitt Peak National Observatory/12 meter Telescope KPNO.2.1m Kitt Peak National Observatory/2.1 meter Telescope KPNO.BT Kitt Peak National Observatory/Bok Telescope KPNO.MAYALL Kitt Peak National Observatory/Mayall Telescope KPNO.MDMHT Kitt Peak National Observatory/MDM Hitner Telescope KPNO.MDMMH Kitt Peak National Observatory/MDM HcGraw-Hill Telescope KPNO.MPT Kitt Peak National Observatory/McMath-Pierce Telescope KPNO.SARA Kitt Peak National Observatory/Southeastern Association for Reasearch in Astronomy Telescope KPNO.SWT Kitt Peak National Observatory/Space Watch Telescope KPNO.WIYN Kitt Peak National Observatory/WYIN, Wisconson-Indiana-Yale-NOAO Telescope CTIO.1.5m Cerro Tololo Inter-American Observatory/1.5 meter Telescope CTIO.2MASS Cerro Tololo Inter-American Observatory/2MASS Telescope CTIO.VBT Cerro Tololo Inter-American Observatory/Victor Blanco Telescope CTIO.YALO Cerro Tololo Inter-American Observatory/YALO, Yale-AURA-Lisbon-OU Telescope The syntax that was suggested was observatoryLocation.telescope as the way of identifying datasets in a way that will be most straightforware for users. This list was suggested by someone at ApJ as I recall. There has been some discussion about how and if these should be tied to organizations. One concern with organizational ties is that these ID's are intended to be permanent. So 50 years from it may be irrelevant to users that a particular telescope was for a time run by a given organization, and it's certainly possible that control of a telescope (and its data) will shift from one organization to another over the course of its lifetime. In the NASA world, that's actually quite normal. First, note that the "National Optical Astronomy Observatory" is not mentioned yet NOAO is likely the legal owner of many data products resulting from some of these facilities. Second, note: 1) that data from KPNO.12m is owned (I would think) by *NRAO* (as is the telescope), 2) that data from KPNO.BT and KPNO.SWT is owned by the University of Arizona (or perhaps the state of Arizona), 3) that data from KPNO.MPT is owned by the National Solar Observatory, 4) that data from KPNO.MDMHT and KPNO.MDMMH is owned by whoever owned MDM during the epoch of the observations in question, 5) that data from KPNO.SARA is owned by the SARA consortium, 6) that data from KPNO.WIYN is owned by the WIYN consortium, one member of which is NOAO, 7) that there are two 2MASS telescopes and only one is at CTIO 8) that CTIO.YALO was run by the - you guessed it - YALO consortium and has since ceased operations Right, our thought is that organizations will register as responsible for particular dataset holdings. So, e.g., the YALO consoritium would have registered as responsible for that holding and when it ceased operations whoever has inherited responsibility for the holding (if anyone) could register as the responsible party. Thus the granularity of the datasets holdings needs to be small enough that a single party is likely to be responsible for each. It is quite likely that I got some of those nuances wrong myself :-) There appears to be a confusion between a ground-based observing site and an observatory - perhaps this is a result of the list being compiled by our friends in the space-based astronomical community? No... As I mentioned above we didn't do this. If we had we surely wouldn't have lumped all space observatories together! It may be that rather than KPNO and CTIO they should be KP and CT. That certainly seems reasonable to me. I don't think this list is set in concrete or even particularly old jello. In general an observatory is a political entity, a telescope is a facility, and a site like Kitt Peak is a piece of real estate that may be host multiple facilities from multiple observatories. Depending on the details of contracts or other binding operating agreements, an observatory may "own" the data that result from a particular facility like a telescope, instrument, archive or pipeline - or that ownership may devolve to a specific member of some consortium. In many cases, one imagines that a funding agency or government or perhaps even the "people of the United States of America" may ultimately own a particular data product. So, an example. NOAO operates twin 8Kx8K mosaic wide field imagers at its sites on Kitt Peak in Arizona and on Cerro Tololo in Chile. Depending on the phase of the moon (quite literally :-) the resulting data may be owned by NOAO or by some instrumentalities associated with the University of Wisconsin, Indiana University, Yale University and in the near future perhaps the University of Maryland. Confounded with this question of ownership is the issue of proprietary rights. Time on NOAO facilities is awarded competitively and the successful PIs are rewarded with sole access for some period (typically 18 months). All of these issues are certainly complex, but in some sense they are irrelevant. Either the organizations can work out some agreements about how data are named that can be put into a dataset id, or they can't and it won't happen. I don't think we need to solve every problem to have a useful capability. A dataset ID can be a relatively simple beast - perhaps as simple as a data source ID and a serial number. But the full taxonomy of dataset provenance has to support many degrees of freedom. At the very least: Nation Funding agency Observatory Consortium member ("partner") Telescope Instrument Date&Time Proposal ID PI and/or project ID ... Here I think you are confusing the metadata describing an observation with the 'name' of an observation. Why should an ID have the time? One might choose to use the time in the ID. But there is not reason why it has to be done that way. Why does it need a proposal ID, nation, agency? Again you can choose to put them there, but I see no requirement why the general ID specification needs to include this. We are not trying to use the ID as a way of encapsulating the description of the dataset, just a way to point to it. The more I listen to myself talk, the more I convince (myself, anyway :-) that a single DS_IDENT keyword is a very poor match to the underlying requirements. Not only might a single file belong to multiple datasets certified by a particular entity (like ADS), but they may belong to multiple other datasets certified by multiple other entities - and more to the point, the design of the certification process will vary from one to the next to the next. In particular, the NOAO Science Archive has been discussing the precise questions of ownership and proprietary access and had already selected a subset of fields along the lines of Observatory (NOAO, WIYN, SOAR, etc.), Partner (NOAO, Wisconsin, Indiana, Yale, Brazil, etc.), Telescope (kp4m, ct4m, wiyn, soar, etc.), Instrument (too many to list), Date&Time, and (most similar to the ADS scheme) the NOAO Proposal ID spanning all these facilities. Whatever we settle on will never fit within the confines of any single keyword. On the other hand, I'd love to *also* include an ADSID tag to even further constrain the provenance. Agreeing on metadata fields is great, but I think it's largely orthogonal to the question of whether we want a dataset id somewhere as indeed your last comment suggests. |
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[fitsbits] 'Dataset Identifications' postings (digest)
Arnold Rots writes:
Maybe it helps to state the practical purpose of the identifiers. It's put in there to inform users as to what dataset identifier to use if and when they insert such identifiers into their manuscripts. Thanks! Yes, that does help. The purpose of that is to facilitate the linkage between the literature and the archived datasets. Those links are currently being maintained by a number of data centers (and the ADS) but it is rather labor-intensive. This mechanism would allow for automatic harvesting. An eminently desirable goal. This causes me to strengthen my recommendation that the reserved keyword name(s) be ADSID and ADSIDnnn. (I imagine a thousand ADS dataset identifiers are sufficient for a particular FITS HDU - are they?) You will find the current list at: http://vo.ads.harvard.edu/dv/facilities.txt A very interesting list. Might I suggest that this list be itself scrubbed and extended as part of this process? There is a lot of confusion about the organizations contained on the list. For instance, here are the overtly NOAO related entries: KPNO.12m Kitt Peak National Observatory/12 meter Telescope KPNO.2.1m Kitt Peak National Observatory/2.1 meter Telescope KPNO.BT Kitt Peak National Observatory/Bok Telescope KPNO.MAYALL Kitt Peak National Observatory/Mayall Telescope KPNO.MDMHT Kitt Peak National Observatory/MDM Hitner Telescope KPNO.MDMMH Kitt Peak National Observatory/MDM HcGraw-Hill Telescope KPNO.MPT Kitt Peak National Observatory/McMath-Pierce Telescope KPNO.SARA Kitt Peak National Observatory/Southeastern Association for Reasearch in Astronomy Telescope KPNO.SWT Kitt Peak National Observatory/Space Watch Telescope KPNO.WIYN Kitt Peak National Observatory/WYIN, Wisconson-Indiana-Yale-NOAO Telescope CTIO.1.5m Cerro Tololo Inter-American Observatory/1.5 meter Telescope CTIO.2MASS Cerro Tololo Inter-American Observatory/2MASS Telescope CTIO.VBT Cerro Tololo Inter-American Observatory/Victor Blanco Telescope CTIO.YALO Cerro Tololo Inter-American Observatory/YALO, Yale-AURA-Lisbon-OU Telescope First, note that the "National Optical Astronomy Observatory" is not mentioned yet NOAO is likely the legal owner of many data products resulting from some of these facilities. Second, note: 1) that data from KPNO.12m is owned (I would think) by *NRAO* (as is the telescope), 2) that data from KPNO.BT and KPNO.SWT is owned by the University of Arizona (or perhaps the state of Arizona), 3) that data from KPNO.MPT is owned by the National Solar Observatory, 4) that data from KPNO.MDMHT and KPNO.MDMMH is owned by whoever owned MDM during the epoch of the observations in question, 5) that data from KPNO.SARA is owned by the SARA consortium, 6) that data from KPNO.WIYN is owned by the WIYN consortium, one member of which is NOAO, 7) that there are two 2MASS telescopes and only one is at CTIO 8) that CTIO.YALO was run by the - you guessed it - YALO consortium and has since ceased operations It is quite likely that I got some of those nuances wrong myself :-) There appears to be a confusion between a ground-based observing site and an observatory - perhaps this is a result of the list being compiled by our friends in the space-based astronomical community? In general an observatory is a political entity, a telescope is a facility, and a site like Kitt Peak is a piece of real estate that may be host multiple facilities from multiple observatories. Depending on the details of contracts or other binding operating agreements, an observatory may "own" the data that result from a particular facility like a telescope, instrument, archive or pipeline - or that ownership may devolve to a specific member of some consortium. In many cases, one imagines that a funding agency or government or perhaps even the "people of the United States of America" may ultimately own a particular data product. So, an example. NOAO operates twin 8Kx8K mosaic wide field imagers at its sites on Kitt Peak in Arizona and on Cerro Tololo in Chile. Depending on the phase of the moon (quite literally :-) the resulting data may be owned by NOAO or by some instrumentalities associated with the University of Wisconsin, Indiana University, Yale University and in the near future perhaps the University of Maryland. Confounded with this question of ownership is the issue of proprietary rights. Time on NOAO facilities is awarded competitively and the successful PIs are rewarded with sole access for some period (typically 18 months). A dataset ID can be a relatively simple beast - perhaps as simple as a data source ID and a serial number. But the full taxonomy of dataset provenance has to support many degrees of freedom. At the very least: Nation Funding agency Observatory Consortium member ("partner") Telescope Instrument Date&Time Proposal ID PI and/or project ID ... The more I listen to myself talk, the more I convince (myself, anyway :-) that a single DS_IDENT keyword is a very poor match to the underlying requirements. Not only might a single file belong to multiple datasets certified by a particular entity (like ADS), but they may belong to multiple other datasets certified by multiple other entities - and more to the point, the design of the certification process will vary from one to the next to the next. In particular, the NOAO Science Archive has been discussing the precise questions of ownership and proprietary access and had already selected a subset of fields along the lines of Observatory (NOAO, WIYN, SOAR, etc.), Partner (NOAO, Wisconsin, Indiana, Yale, Brazil, etc.), Telescope (kp4m, ct4m, wiyn, soar, etc.), Instrument (too many to list), Date&Time, and (most similar to the ADS scheme) the NOAO Proposal ID spanning all these facilities. Whatever we settle on will never fit within the confines of any single keyword. On the other hand, I'd love to *also* include an ADSID tag to even further constrain the provenance. Rob Seaman NOAO Science Data Systems |
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