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Merging entries?

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  • James Bedient
    Is there a way to merge or link two entries that are the same star? ASAS 201608-5051.6 and NSV 12938 are one and the same. Should I just revise them both to
    Message 1 of 6 , Nov 25, 2006
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      Is there a way to merge or link two entries that are the same star?
      ASAS 201608-5051.6 and NSV 12938 are one and the same. Should I just
      revise them both to the same position (a good one from NOMAD1 in this
      case) or what's the protocol?

      Jim

      ---------------------------------------------
      Jim Bedient
      jbedient@...
      www.bedient.us
    • Patrick Wils
      Jim, Linking two entries and then hiding one of them, is a functionality that is only available to moderators at this moment. In this case the two entries
      Message 2 of 6 , Nov 26, 2006
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        Jim,

        Linking two entries and then "hiding" one of them, is a functionality that
        is only available to moderators at this moment. In this case the two
        entries are already linked. This can be seen because the name of the
        other entry appears in bold in the "Other names" section. By clicking it,
        you can see the detail sheet of this other entry.
        The best way to proceed is to update one entry (I suggest NSV 12938 in
        this case) with all the recent info, and we will then make sure the other
        entry is "hidden". This means that the entry will no longer appear in a
        coordinate search, but can still be reached from the "Other names" section
        of the "main" entry.

        Patrick

        --- James Bedient <jbedient@...> wrote:

        > Is there a way to merge or link two entries that are the same star?
        > ASAS 201608-5051.6 and NSV 12938 are one and the same. Should I just
        > revise them both to the same position (a good one from NOMAD1 in this
        > case) or what's the protocol?
        >
        > Jim
        >
        > ---------------------------------------------
        > Jim Bedient
        > jbedient@...
        > www.bedient.us
        >




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      • flying.visit
        ... Let us get this sorted straight off... ...there are no such thing as NOMAD1 positions, no moreso nor nomoreless than there are VizieR positions. This
        Message 3 of 6 , Nov 29, 2006
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          --- In vsx-dis@yahoogroups.com, "James Bedient" <jbedient@...> wrote:

          > ASAS 201608-5051.6 and NSV 12938 are one and the same. Should I just
          > revise them both to the same position (a good one from NOMAD1 in this
          > case)

          Let us get this sorted straight off...

          ...there are no such thing as NOMAD1 positions, no moreso nor
          nomoreless than there are VizieR positions.

          This position is an UCAC2 position.

          It is even flagged as an UCAC2 position in NOMAD.

          As soon as NOMAD got included in VizieR I new this bad habit would start.

          There is no reprocessing in NOMAD, nor any criticial assessment, it
          merely has a Tycho2->UCAC2->USNO B1.0 hierarchy, with 2MASS thrown in
          if the object is not in any of the above.

          EXCEPT for one exception. The YB6 data that is flagged in NOMAD
          appears in NOMAD only, and as such is tantamount to being "published"
          in NOMAD.

          The YB6 data is USNO astrometry group's inhouse digitization and
          astrometric reduction of Yale proper motion survey plates. Commonly
          the user will find that most of these objects uniquely attributed to
          this catalogue as their reference source within NOMAD are in fact
          close to other, often brighter, stars, and therefore were missed due
          to resolution/proximity issues in UCAC2 reduction and/or USNO B1.0
          overexposed source stars hid them (Yale stuff is not quite as deep as
          POSS).

          However, the YB6 data has _not_ been formally published, no paper
          trail exists for it, and although it can be assumed that the same team
          that did USNO An.0 and B1.0 was also capable of making a good job of
          YB6, no independent large scale source of it exists (just happenstance
          smatterings returned from any NOMAD search via either NOFS or VizieR)
          and unlike UCAC2 and USNO B1.0 there have consequently been no
          attempts to use it exclusively in astrometric reductions in order to
          assess its quality.

          Further, and significantly, the lack of a formal published paper on it
          (it may well be mentioned in passing in the NOMAD announce paper, if
          such latter exists, but that ain't the same thing), means it has no
          bibliographic referenceable peer reviewed literature backup. In terms
          of VSX this would mean astrometry would be adopted that was in
          scientific terms tantamount to hearsay. No matter how good it may in
          the end be shown to be, it is not at present either tested or
          published, in other words.

          Summary, there are no NOMAD positions. Use the source Jim, it's
          astrometry, but not as we know it.

          Incidentally, any errors or problems inherent to Tycho2, UCAC2 and/or
          USNO B1.0 are, of course, also retained within NOMAD, which is a
          working acronym not dissimilar in wordage to SIMBAD, which itself is
          well known to suffer being apocryphal from time to time.

          All this, of course, assumes VSX actually deigns to note the
          astrometric source of its quality positions, I can't remember whether
          it does or not, over and above the imported inference via GCVS
          astrometric referencing.

          John

          PS When more VO stuff comes in folk are going to have to keep their
          brain ready for stuff like this. It's not a new distinction,
          catalogue and data users have had to be aware of it for years, but
          ostensibly it's more "hidden" in this case. Simply think "is this a
          catalogue or a VizieR like lookup table?". Now the damn thing's in
          VizieR people are using it more (it's been around several years), not
          realising they are just looking at Tycho2, UCAC2 or USNO B1.0 data
          _third hand_! Worst still, if NOMAD is accessed via a general VizieR
          coordinate search then said source Tcyho2, UCAC2 and USNO B1.0 entries
          are also going to appear in the same VizieR output, along with
          attendant discriminatory flags and astrometric errors for
          intercomparison of these sources, yet folk ignore them and quote NOMAD
          as if it was somehow better just because it was newer!!!
          (Professionals and amateurs alike, it ain't just in this instance...
          ...interesting Jim's in the company of his "old pals" the GCVS in this
          instance with respect to this recent practice).

          Accreditation causes more trouble than enough, usually coz it is
          cocked up. If folk think about it in terms of audit trail, or
          remember how annoyed they get trying to look up references they've
          found in the literature that _do not_ lead to primary sources, they
          might get the gist of the matter.

          VSX does not want to be a source of meaningless fundamental reference
          material. NOMAD is not an primary source astrometric catalogue in
          terms of quotability, being merely a compilation. It contains such
          information but is not a result of generating said. Granted it flags
          the true primary source and generating catalogue within it, well, if
          that's the case, quote said primary source!

          Incidentally, there appears to be no critical assessment with respect
          to the source they chose for any particular object, such that a faint
          limit Tycho2 star may well be chosen in their general merging of
          databases whereas the UCAC2 position, nested in the middle of the
          dynamic photometric range, may well be more accurate in terms of both
          position and certainly proper motion. This particular object is
          flagged in NOMAD as also being in YB6 and 2MASS... ...yet the UCAC2
          position was chosen. Quite frankly, as it is a quite red object it
          will be overexposed in 2MASS. It's neither overexposed nor near the
          faint limit in UCAC2 so that is likely the best source in this
          instance, yet a tighter, crisper image is still most likely to occur
          in the YB6 blue plate. But as I say, this latter is unpublished and
          really shouldn't be used unless there is no alternative whatsoever, so
          UCAC2 still works as the best case in this instance.


          What VSX does want to have are IBVS variables included, and further,
          AAVSO does want to mention VSX everytime it announces an alert about a
          new variable not being in various catalogues, as VSX contains more
          variables than the resources AAVSO usually mentions... ...this is over
          and above the connection between VSX and AAVSO: AAVSO staff should
          look in VSX on such occasions even if the damn thing was totally
          unrelated.

          I'm not impressed yet. And contrary to popular belief I can be
          impressed, and it even don't take much to impress me.
        • arne
          ... See below. ... perhaps for B1.0, but rarely for UCAC2. UCAC2 is CCD-based, with a small telescope and decent sampling. It does a good job of picking up
          Message 4 of 6 , Nov 29, 2006
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            flying.visit wrote:
            > --- In vsx-dis@yahoogroups.com, "James Bedient" <jbedient@...> wrote:
            >
            >
            >>ASAS 201608-5051.6 and NSV 12938 are one and the same. Should I just
            >>revise them both to the same position (a good one from NOMAD1 in this
            >>case)
            >
            >
            > Let us get this sorted straight off...
            >
            > ...there are no such thing as NOMAD1 positions, no moreso nor
            > nomoreless than there are VizieR positions.
            >
            See below.
            >
            > The YB6 data is USNO astrometry group's inhouse digitization and
            > astrometric reduction of Yale proper motion survey plates. Commonly
            > the user will find that most of these objects uniquely attributed to
            > this catalogue as their reference source within NOMAD are in fact
            > close to other, often brighter, stars, and therefore were missed due
            > to resolution/proximity issues in UCAC2 reduction and/or USNO B1.0
            > overexposed source stars hid them (Yale stuff is not quite as deep as
            > POSS).
            >
            perhaps for B1.0, but rarely for UCAC2. UCAC2 is CCD-based, with a
            small telescope and decent sampling. It does a good job of picking
            up faint stars near bright ones.

            > However, the YB6 data has _not_ been formally published, no paper
            > trail exists for it, and although it can be assumed that the same team
            > that did USNO An.0 and B1.0 was also capable of making a good job of
            > YB6, no independent large scale source of it exists (just happenstance
            > smatterings returned from any NOMAD search via either NOFS or VizieR)
            > and unlike UCAC2 and USNO B1.0 there have consequently been no
            > attempts to use it exclusively in astrometric reductions in order to
            > assess its quality.
            >
            YB6 is semi-published, in that it is a combination of NPM and SPM, where
            SPM is published. NPM is in the process of publication.


            > All this, of course, assumes VSX actually deigns to note the
            > astrometric source of its quality positions, I can't remember whether
            > it does or not, over and above the imported inference via GCVS
            > astrometric referencing.
            >
            > VSX does not want to be a source of meaningless fundamental reference
            > material. NOMAD is not an primary source astrometric catalogue in
            > terms of quotability, being merely a compilation. It contains such
            > information but is not a result of generating said. Granted it flags
            > the true primary source and generating catalogue within it, well, if
            > that's the case, quote said primary source!
            >
            It keeps getting more difficult to do this. For example, if you
            go to VizieR and get the UCAC2 position for an object, that is *not*
            the UCAC2 position, but one that is propogated with proper motion
            from the original epoch to 2000.0. I don't consider VSX to be
            a great source for astrometric information and so have not pushed
            hard on getting the most precise position.

            > Incidentally, there appears to be no critical assessment with respect
            > to the source they chose for any particular object, such that a faint
            > limit Tycho2 star may well be chosen in their general merging of
            > databases whereas the UCAC2 position, nested in the middle of the
            > dynamic photometric range, may well be more accurate in terms of both
            > position and certainly proper motion. This particular object is
            > flagged in NOMAD as also being in YB6 and 2MASS... ...yet the UCAC2
            > position was chosen. Quite frankly, as it is a quite red object it
            > will be overexposed in 2MASS. It's neither overexposed nor near the
            > faint limit in UCAC2 so that is likely the best source in this
            > instance, yet a tighter, crisper image is still most likely to occur
            > in the YB6 blue plate. But as I say, this latter is unpublished and
            > really shouldn't be used unless there is no alternative whatsoever, so
            > UCAC2 still works as the best case in this instance.
            >
            YB6 is photographic, so has the typical 200mas/measurement error.
            UCAC2 is much better, so the right choice of astrometric catalog was
            chosen. Primarily, YB6 is used for photometry (B&V) and proper motion;
            few NOMAD astrometric positions are derived from this catalog.

            >
            > What VSX does want to have are IBVS variables included, and further,
            > AAVSO does want to mention VSX everytime it announces an alert about a
            > new variable not being in various catalogues, as VSX contains more
            > variables than the resources AAVSO usually mentions... ...this is over
            > and above the connection between VSX and AAVSO: AAVSO staff should
            > look in VSX on such occasions even if the damn thing was totally
            > unrelated.
            >
            point taken. I've tried to make sure all staff refer to VSX when
            publishing. In this particular case, the other catalogs (NSVS, ASAS)
            were mentioned in that no star appeared in either catalog at the
            VarLeo06 position, not that we referenced the variability
            products from those surveys.
            Arne
          • fly.ingvisit
            ... nothing closer than six arcseconds apart, unless special hand inputted cases from known classical catalogues, are included in UCAC2, ie anything that close
            Message 5 of 6 , Nov 29, 2006
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              --- In vsx-dis@yahoogroups.com, arne <arne@...> wrote:

              > perhaps for B1.0, but rarely for UCAC2. UCAC2 is CCD-based, with a
              > small telescope and decent sampling. It does a good job of picking
              > up faint stars near bright ones.

              nothing closer than six arcseconds apart, unless special hand inputted
              cases from known classical catalogues, are included in UCAC2, ie
              anything that close together was not normally reduced in the analysis.

              this is one of the big differences to be undertaken in UCAC3, along
              with other considerations.

              > YB6 is semi-published, in that it is a combination of NPM and SPM, where
              > SPM is published. NPM is in the process of publication.

              I'd have to look that up. In my understanding the Yale analysis was
              the Yale analysis, already published as you note for SPM and for NPM2,
              which are on the same system as I remember, but the YB6 was an
              independent reduction by USNO from the digitized data they provided to
              Yale. The YB6 may even cover regions which SPM3.3 and NPM2
              deliberately avoid in the reduction but may well have been imaged...
              ...I've never been sure if these places were just avoided in the
              reduction or never imaged initially.

              > It keeps getting more difficult to do this. For example, if you
              > go to VizieR and get the UCAC2 position for an object, that is *not*
              > the UCAC2 position, but one that is propogated with proper motion
              > from the original epoch to 2000.0.

              Wrong.

              VizieR will include what you mention if you want it to, it may even
              default include it if those options aren't unticked, but the original
              source catalogue values are still included. For this object you will
              note that ucac2 and nomad1 entries say the same thing, the source
              ucac2 catalog decimal degrees position.

              VizieR often includes extras but keeps the original source data too.
              The only place offhand that I can remember where they don't do this is
              for the cos(dec) correction to ra proper motion in Tycho2, UCAC2 and
              possibly USNO B1.0.

              > I don't consider VSX to be
              > a great source for astrometric information and so have not pushed
              > hard on getting the most precise position.

              Fair enough.

              > YB6 is photographic, so has the typical 200mas/measurement error.
              > UCAC2 is much better, so the right choice of astrometric catalog was
              > chosen. Primarily, YB6 is used for photometry (B&V) and proper motion;
              > few NOMAD astrometric positions are derived from this catalog.

              When you go looking for double stars you find where all the ones used
              are, they're often near brighter stars on the whole missed from the
              other catalogues because of this, but also UCAC2 doesn't always go too
              faint (YB6 will go down to 17 or 18 or so, UCAC2 can often stop at
              around 14 or so, albeit sometimes much fainter) and again, UCAC2 has
              this six arcsecond thing, which can come into play more than expected.

              Incidentally, I've noted to this to some before, YB6 colours are
              noncontemporaneous, and therefore useless for variable objects.

              John
            • James Bedient
              OK, in that I have a wife, two daughters, three cats, three cars, a house, a real job, etc., I haven t spent my life studying astrometric catalogs. When
              Message 6 of 6 , Nov 29, 2006
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                OK, in that I have a wife, two daughters, three cats, three cars, a
                house, a real job, etc., I haven't spent my life studying astrometric
                catalogs. When NOMAD1 popped up on VizieR, I read the "read me" and
                figured when it said "For each unique star the "best" astrometric and
                photometric data are chosen from the source catalogs and merged into a
                single dataset." that they meant it.

                As long as the source of a piece of data is identified, I don't think
                it matters a hoot where it's from, GSC or UCAC or USNO or whatever.
                It's traceable back.
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