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Too bright comet magnitude estimates?

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  • Maik Meyer
    Dear friends, I am again quite astonished about the very bright magnitude estimates I have just found on the updated IQC recent magnitudes pages (in brackets
    Message 1 of 3 , Sep 2, 2001
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      Dear friends,

      I am again quite astonished about the very bright magnitude estimates I
      have just found on the updated IQC recent magnitudes pages (in brackets the
      average of other experienced observers):

      C/2000 SV74 : 12.6 mag (13.5 mag)
      C/2000 WM1 : 11.5 mag !!! (13.5 mag)
      19P/Borrelly : 8.6 mag (10 mag)

      P/2001 Q2 (Petriew) is not listed - I guess Dan just forgot it. The scatter
      in the estimates of C/2001 A2 is easy to explain: the comet is quite
      diffuse, so I have not listed it. But I find no explanations for the
      others. Other experienced observers differ from the above magnitudes as
      much as 2 mag!

      Is there something wrong with our magnitude estimation techniques that such
      scatter can occur even for moderate condensed comets? I think such scatter
      must not appear...

      Regards

      Maik
      --
      If they give you ruled paper, write the other way. * Juan Ramon Jimenez
      ________________________________________________________________________
      maik@... http://www.comethunter.de
      German Comet Section http://www.fg-kometen.de
      http://groups.yahoo.com/group/comets-ml
    • Maciej Reszelski
      Hi Maik! ... Difference between estimates is not quite high. So, I suppose with this one is OK. Especially that DC is about 2-3 from my obs... ... Yes!!! I
      Message 2 of 3 , Sep 2, 2001
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        Hi Maik!

        > C/2000 SV74 : 12.6 mag (13.5 mag)

        Difference between estimates is not quite high. So,
        I suppose with this one is OK. Especially that DC is
        about 2-3 from my obs...

        > C/2000 WM1 : 11.5 mag !!! (13.5 mag)

        Yes!!! I must ask Martin what's going with this.
        Martin often using HS reference. Reinder (suppose)
        and I AC = AAVSO charts often based on Arne Henden
        photometry... Maybe GSC errors? What are values
        of errors in this region?

        > 19P/Borrelly : 8.6 mag (10 mag)

        Another: must ask
        >
        > P/2001 Q2 (Petriew) is not listed - I guess Dan just forgot it. The
        scatter
        > in the estimates of C/2001 A2 is easy to explain: the comet is quite

        Yeap DC is about 0-1. And location -- rich star-fileds. Horrible! :)

        > diffuse, so I have not listed it. But I find no explanations for the
        > others. Other experienced observers differ from the above magnitudes as
        > much as 2 mag!
        >

        Cheers,
        MJ
        > Is there something wrong with our magnitude estimation techniques that
        such
        > scatter can occur even for moderate condensed comets? I think such scatter
        > must not appear...
        >
        > Regards
        >
        > Maik
        > --
        > If they give you ruled paper, write the other way. * Juan Ramon Jimenez
        > ________________________________________________________________________
        > maik@... http://www.comethunter.de
        > German Comet Section http://www.fg-kometen.de
        > http://groups.yahoo.com/group/comets-ml
        >
        >
        > To unsubscribe from this group, send an email to:
        > comets-ml-unsubscribe@yahoogroups.com
        >
        >
        >
        > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
        >
        >
        >
      • rigel_ori@hotmail.com
        Hi, Maik, and Maciej. You are both puzzled by the differences in your mag estimates and those of others as reported by Dan Green in his latest Magnitude
        Message 3 of 3 , Sep 2, 2001
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          Hi, Maik, and Maciej. You are both puzzled by the differences in
          your mag estimates and those of others as reported by Dan Green in
          his latest Magnitude estimates listing. Maybe it is not the
          magnitude references that you are using. Dan Green and Charles
          Morris have tried to address this problem a number of times, and they
          usually associate it to be either the magnitude reference, or the
          estimation techniques (ie. Bobrovnikoff, Sidgwick, or Morris methods).

          I am listing some references to such articles as found in the
          International Comet Quarterly.

          "A Review of Visual Comet Observing Techniques -- I", Charles S.
          Morris, October 1980, ICQ 2, pgs. 69-73

          "A Review of Visual Comet Observing Techniques -- II", Charles S.
          Morris, January 1981, ICQ 3, pgs. 3-5

          "A Review of Visual Comet Obsrving Techniques -- III", Charles S.
          Morris, July 1981, ICQ 3, pgs 89-90

          "Of Sequences and Comparison Star Magnitudes", Henk Feijth, October
          1980, ICQ ICQ 2, pgs. 73-74

          "Some Thoughts on Limiting Visual and Cometary Magnitudes with
          Various Apertures", Ganiel W. E. Green, April 1985, ICQ 7, pgs 40-46

          "Review of Magnitude Sources for Visual Cometary Photometry. I",
          Daniel Green and Charles Morris, January 1982, ICQ 4, pgs 5-10

          "Review of Magnitude Sources for Visual Cometary Photometry. II"
          Charles Morris and Daniel Green, July 1982, ICQ 4, pgs 62-63

          "Quantized Beyer's Method (QBM), to Estimate accurately the
          brightness of Extended Objects" Ignacia Ferrin, in 'Research Amateur
          Astronomy' ASP Conference Series, Vol. 33, 1992 Stephen J. Edberg,
          (ed.), pgs 123-134

          "Tabulation of Comet Observations", Dan Green, October 1997, ICQ
          19,4 pgs 224-226

          "Visual limiting magnitude determination charts", Alastair McBeath,
          J. Br. Astron. Assoc., 101, 4, 1991, pgs 213-218

          "Visual Magnitudes and the S. A. O. Catalog", David Herald, April
          1981, ICQ 3, pgs 43-44

          As can be seen there is a long list of literture dealing with this
          prblem. I am sure I missed some over the years. Good luck,
          Bob Warren, rigel_ori@...; OCS




          --- In comets-ml@y..., "Maciej Reszelski" <macres@p...> wrote:
          > Hi Maik!
          >
          > > C/2000 SV74 : 12.6 mag (13.5 mag)
          >
          > Difference between estimates is not quite high. So,
          > I suppose with this one is OK. Especially that DC is
          > about 2-3 from my obs...
          >
          > > C/2000 WM1 : 11.5 mag !!! (13.5 mag)
          >
          > Yes!!! I must ask Martin what's going with this.
          > Martin often using HS reference. Reinder (suppose)
          > and I AC = AAVSO charts often based on Arne Henden
          > photometry... Maybe GSC errors? What are values
          > of errors in this region?
          >
          > > 19P/Borrelly : 8.6 mag (10 mag)
          >
          > Another: must ask
          > >
          > > P/2001 Q2 (Petriew) is not listed - I guess Dan just forgot it.
          The
          > scatter
          > > in the estimates of C/2001 A2 is easy to explain: the comet is
          quite
          >
          > Yeap DC is about 0-1. And location -- rich star-fileds. Horrible! :)
          >
          > > diffuse, so I have not listed it. But I find no explanations for
          the
          > > others. Other experienced observers differ from the above
          magnitudes as
          > > much as 2 mag!
          > >
          >
          > Cheers,
          > MJ
          > > Is there something wrong with our magnitude estimation techniques
          that
          > such
          > > scatter can occur even for moderate condensed comets? I think
          such scatter
          > > must not appear...
          > >
          > > Regards
          > >
          > > Maik
          > > --
          > > If they give you ruled paper, write the other way. * Juan Ramon
          Jimenez
          > >
          ______________________________________________________________________
          __
          > > maik@c... http://www.comethunter.de
          > > German Comet Section http://www.fg-kometen.de
          > > http://groups.yahoo.com/group/comets-ml
          > >
          > >
          > > To unsubscribe from this group, send an email to:
          > > comets-ml-unsubscribe@y...
          > >
          > >
          > >
          > > Your use of Yahoo! Groups is subject to
          http://docs.yahoo.com/info/terms/
          > >
          > >
          > >
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