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Re: {MPML} USNO-B1.0 announced

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  • David Tholen
    ... First four bytes are the RA. Next four bytes are the Dec. Next four bytes are the two proper motions in packed format. Next four bytes are the
    Message 1 of 13 , Sep 14, 2002
      > Thanks for the info. I'm curious about the size of the new catalog. The A2 with
      > about 550M spans 11 standard CDs and takes up 7GB, plus or minus. Doubling that
      > number - to the 1E9 stars - would make the size in the neighborhood of 14GB.
      > What extra data is being included that would make the catalog nearly 7x larger?
      > It would seem proper motion and mag data wouldn't take up that much extra room,
      > especially given the way the data was compacted in the A2 catalog.

      First four bytes are the RA.
      Next four bytes are the Dec.
      Next four bytes are the two proper motions in packed format.
      Next four bytes are the uncertainties in the motions in packed format.
      Next four bytes are the uncertainties in the positions in packed format.
      Next four bytes are the blue magnitude and plate information.
      Next four bytes are the red magnitude and plate information.
      Next four bytes are the second blue magnitude and plate information.
      Next four bytes are the second red magnitude and plate information.
      Next four bytes are the N magnitude and plate information.
      Next four bytes are the blue magnitude uncertainty and calibration source.
      Next four bytes are the red magnitude uncertainty and calibration source.
      Next four bytes are the second blue magnitude uncertainty etc.
      Next four bytes are the second red magnitude uncertainty etc.
      Next four bytes are the N magnitude uncertainty etc.
      Next four bytes are the first blue lookback index into PMM scan file.
      Next four bytes are the first red lookback index into PMM scan file.
      Next four bytes are the second blue lookback index into PMM scan file.
      Next four bytes are the second red lookback index into PMM scan file.
      Last four bytes are the N survey lookback index into PMM scan file.

      That's 80 bytes per record, compared with 12 for the A catalog. So, a
      factor of 6.7 more information and a factor of 2 more stars. Much of
      the information is not of immediate interest to most users, so a
      smaller version could be created. I for one applaud the inclusion of
      uncertainty information.

      With the exception of RA and DEC, all the other fields are in packed
      format with little things stuck in there, like the number of detections,
      the star/galaxy flag, the mean epoch, etc.
    • Brian Warner
      David, Thanks! I agree, the uncertainty values are important and should be included. Knowing budget constraints, I doubt we ll see a cutback version. Clear
      Message 2 of 13 , Sep 14, 2002
        David,

        Thanks! I agree, the uncertainty values are important and should be included.

        Knowing budget constraints, I doubt we'll see a cutback version.


        Clear Skies,
        Brian Warner
        Palmer Divide Observatory (716)
        Colorado Springs, CO
        http://www.MinorPlanetObserver.com

        Collaborative Asteroid Lightcurve Link (CALL)
        http://www.MinorPlanetObserver.com/astlc/default.htm


        ----- Original Message -----
        From: "David Tholen" <tholen@...>
        To: "MPML" <mpml@yahoogroups.com>
        Sent: Saturday, September 14, 2002 03:49
        Subject: Re: {MPML} USNO-B1.0 announced


        > > Thanks for the info. I'm curious about the size of the new catalog. The A2
        with
        > > about 550M spans 11 standard CDs and takes up 7GB, plus or minus. Doubling
        that
        > > number - to the 1E9 stars - would make the size in the neighborhood of 14GB.
        > > What extra data is being included that would make the catalog nearly 7x
        larger?
        > > It would seem proper motion and mag data wouldn't take up that much extra
        room,
        > > especially given the way the data was compacted in the A2 catalog.
        >
        > First four bytes are the RA.
        > Next four bytes are the Dec.
        > Next four bytes are the two proper motions in packed format.
        > Next four bytes are the uncertainties in the motions in packed format.
        > Next four bytes are the uncertainties in the positions in packed format.
        > Next four bytes are the blue magnitude and plate information.
        > Next four bytes are the red magnitude and plate information.
        > Next four bytes are the second blue magnitude and plate information.
        > Next four bytes are the second red magnitude and plate information.
        > Next four bytes are the N magnitude and plate information.
        > Next four bytes are the blue magnitude uncertainty and calibration source.
        > Next four bytes are the red magnitude uncertainty and calibration source.
        > Next four bytes are the second blue magnitude uncertainty etc.
        > Next four bytes are the second red magnitude uncertainty etc.
        > Next four bytes are the N magnitude uncertainty etc.
        > Next four bytes are the first blue lookback index into PMM scan file.
        > Next four bytes are the first red lookback index into PMM scan file.
        > Next four bytes are the second blue lookback index into PMM scan file.
        > Next four bytes are the second red lookback index into PMM scan file.
        > Last four bytes are the N survey lookback index into PMM scan file.
        >
        > That's 80 bytes per record, compared with 12 for the A catalog. So, a
        > factor of 6.7 more information and a factor of 2 more stars. Much of
        > the information is not of immediate interest to most users, so a
        > smaller version could be created. I for one applaud the inclusion of
        > uncertainty information.
        >
        > With the exception of RA and DEC, all the other fields are in packed
        > format with little things stuck in there, like the number of detections,
        > the star/galaxy flag, the mean epoch, etc.
        >
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      • David Tholen
        ... Well, I did raise the possibility of creating a smaller version, and Monet didn t object to the notion, though I would imagine that a detailed proposal for
        Message 3 of 13 , Sep 14, 2002
          > Thanks! I agree, the uncertainty values are important and should be included.
          >
          > Knowing budget constraints, I doubt we'll see a cutback version.

          Well, I did raise the possibility of creating a smaller version, and
          Monet didn't object to the notion, though I would imagine that a
          detailed proposal for exactly what would be left out would need to
          be approved by the powers that be. If I remember correctly, he said
          that something like 75 to 80 percent of the entries are within
          something like 10 deg of the galactic plane. There the star density
          is so high that even small fields of view tend to have an adequate
          number of reference stars, so it might be possible to produce a
          catalog with the same number of stars as the A catalog, including
          everything at the higher galactic latitudes, and trimming stars at
          the faint end near the galactic plane. And if you really wanted to
          trim the size, you could propagate the star positions to a epoch of
          something like 2008 (but leaving the equinox at 2000, of course),
          leave out the proper motions, and the catalog would have at most
          five years of uncorrected proper motion for the next decade (that's
          one tenth the size of the uncorrected proper motion we've lived with
          in the A catalog).
        • Michel Ory
          ... Here at station 185 (Vicques,CH) we haven t any high speed internet connection as many other amateur stations. Then I confirm that amateurs are very
          Message 4 of 13 , Sep 14, 2002
            Alain Maury a écrit:

            > What is the use of a catalog that requires you to be on the web most of
            > the night ?
            > Most amateurs, mostly in observatories away from cities don't have a
            > fast link, and must connect through slow modems.
            > Clearly an SB1.0 is needed (à la SA1.0), something that could fit on a
            > few DVD ROMs.
            > Just to mention the most recent DVD engraving desks (for example Sony
            > DRU500A ), which apparently is going to sell in Europe for about 400€,
            > i.e. 400 US$. A 100 Gb hard disk is much cheaper than this.
            > It would be possible to organize a distribution pyramid, with one person
            > having access to the original version could write 3 copies, one for
            > him/her, and send out 2 others. The two recipients would make two
            > copies, sending them out to 2 others (i.e. 4 persons total), which....
            > In 8 turns, 255 MPMLers would be satisfied, without having to require an
            > official distribution.
            > Just a suggestion.
            > Alain

            Here at station 185 (Vicques,CH) we haven't any high speed internet connection as many other amateur stations. Then I confirm that
            amateurs are very interesting about a DVD version of USNO-B1.0. I support the excellent idea of Alain.

            Michel Ory
            185-Vicques
          • Alain Maury
            ... What is the use of a catalog that requires you to be on the web most of the night ? Most amateurs, mostly in observatories away from cities don t have a
            Message 5 of 13 , Sep 15, 2002
              Brian Skiff a écrit:

              >........snip
              >

              > So just two catalogues to worry about: UCAC for brighter than 15th,
              >B1.0 for fainter than 15th.
              >
              >\Brian
              >
              >
              >
              What is the use of a catalog that requires you to be on the web most of
              the night ?
              Most amateurs, mostly in observatories away from cities don't have a
              fast link, and must connect through slow modems.
              Clearly an SB1.0 is needed (à la SA1.0), something that could fit on a
              few DVD ROMs.
              Just to mention the most recent DVD engraving desks (for example Sony
              DRU500A ), which apparently is going to sell in Europe for about 400€,
              i.e. 400 US$. A 100 Gb hard disk is much cheaper than this.
              It would be possible to organize a distribution pyramid, with one person
              having access to the original version could write 3 copies, one for
              him/her, and send out 2 others. The two recipients would make two
              copies, sending them out to 2 others (i.e. 4 persons total), which....
              In 8 turns, 255 MPMLers would be satisfied, without having to require an
              official distribution.
              Just a suggestion.
              Alain
            • Brian Skiff
              When Alain reads the rest of the waiting MPML messages he ll see that something suitable seems to be being considered by Tholen et al. Brian
              Message 6 of 13 , Sep 15, 2002
                When Alain reads the rest of the waiting MPML messages he'll see that
                something suitable seems to be being considered by Tholen et al.

                \Brian
              • Petr Pravec
                ... I, too, would definitely appreciate a special ( SB1.0 ) version of the catalog for use at our site 557. Dave Tholen et al. s considerations are clearly
                Message 7 of 13 , Sep 15, 2002
                  > --- In mpml@y..., Brian Skiff <brian.skiff@l...> wrote:
                  > When Alain reads the rest of the waiting MPML messages he'll see that
                  > something suitable seems to be being considered by Tholen et al.

                  I, too, would definitely appreciate a special ("SB1.0") version of the
                  catalog
                  for use at our site 557. Dave Tholen et al.'s considerations are clearly very
                  good,
                  but are they or somebody actually going to do it? (If needed, I and my
                  colleague
                  can help with the creation of the special version, as I would like to use the
                  best
                  available general catalogue for our routine astrometry work in a most
                  convenient
                  way possible.)

                  Petr Pravec
                  Ondrejov Observatory
                • Bob Denny
                  If a smaller version is produced, please accept my humble suggestion that the bright stars not be sacrificed. This feature of SA2.0 makes it difficult to use
                  Message 8 of 13 , Sep 16, 2002
                    If a smaller version is produced, please accept my humble suggestion that
                    the "bright" stars not be sacrificed. This feature of SA2.0 makes it
                    difficult to use for automatic matching. You are faced with a decision on
                    which "bright" stars in the image to exclude from the initial matching
                    process. Bill Gray has explained this in more detail on his site.

                    Also, I think we need true proper motions. The DVD is a very good way to
                    distribute, many people have readers, and they are super cheap now ($35 US?).

                    -- Bob

                    David Tholen wrote:

                    > Well, I did raise the possibility of creating a smaller version, and
                    > Monet didn't object to the notion, though I would imagine that a
                    > detailed proposal for exactly what would be left out would need to
                    > be approved by the powers that be.
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