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@...
--- 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.
> > in the estimates of C/2001 A2 is easy to explain: the comet is
> 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
> > others. Other experienced observers differ from the above
> > much as 2 mag!
> > Is there something wrong with our magnitude estimation techniques
> > scatter can occur even for moderate condensed comets? I think
> > must not appear...
> > Regards
> > Maik
> > --
> > If they give you ruled paper, write the other way. * Juan Ramon
> > maik@c... http://www.comethunter.de
> > German Comet Section http://www.fg-kometen.de
> > http://groups.yahoo.com/group/comets-ml
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