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Re: [comets-ml] Re: C/2010 X1 recovery attempts.

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  • Alan Hale
    Dear Giovanni, and all, There is still more to the issue. Several visual observers, myself included, have attempted to view this comet, mostly with larger
    Message 1 of 51 , Oct 12, 2011
      Dear Giovanni, and all,

      There is still more to the issue. Several visual observers, myself included,
      have attempted to view this comet, mostly with larger telescopes, and at
      least in my case (and probably most of the others as well) under equally
      good sky conditions -- and have seen nothing.

      On the other hand, there is indeed the curious object in the SECCHI images.
      (I presume the object Alan Watson discussed is the same object Roger Dymock
      mentioned on the mpml list.) There is clearly a moving object in those
      images, but I'm not expert enough with the SECCHI images to determine if
      that is indeed C/2010 X1, or something else, or just what is going on.

      And, of course, there is the almost complete distintegration of the comet
      that Michael Mattiazzo recorded in his images as it approached perihelion,
      and the fact that nothing was seen in the LASCO images as the comet went
      through inferior conjunction.


    • Jakub Černý
      Hello all, I disagree with the term of erroneous observations . Observations can be done with good or bad methology. Whatever some observation does not met
      Message 51 of 51 , Oct 20, 2011
        Hello all,

        I disagree with the term of "erroneous observations". Observations can be
        done with good or bad methology. Whatever some observation does not met our
        expectation, it does not mean it is erroneous.

        I agree that 2 positive visual observations does not prove anything.

        The only conclusion in this case we may tell for sure is that there is no
        evidence yet of detection any remain of comet C/2010 X1 after solar

        Best regards,

        Jakub Cerny

        From: comets-ml@yahoogroups.com [mailto:comets-ml@yahoogroups.com] On Behalf
        Of jbortle@...
        Sent: Thursday, October 20, 2011 5:10 PM
        To: comets-ml@yahoogroups.com
        Subject: Re: [comets-ml] Visual and CCD observations : (was C/2010 X1
        recovery attempts)

        I have been silent throughout this long discussion of the recent supposed
        "positive sightings" of Comet Elenin, but feel I must now speak out. I have
        watched attempts to explain why two questionable positive sightings should
        be regarded as in any way valid in the face of overwhelming negative
        evidence reported by observers with much larger instruments under as good or

        superior skies, and from deep CDD imaging. In the process the potential
        explanations have gone from the questionable to the downright absurd.

        I have been seriously observing comets longer than most here have been
        alive and can tell you that every observer, no matter what his or her
        credentials, instruments, or observing situation, including myself, is open
        making occasional mistaken sightings. Through the years I have seen
        occasions where difficult objects have been reported as "seen" and
        subsequently the observations proven quite impossible. Simply put, when
        by many negative and better observations, it is logical to assume
        immediately that the positive sighting(s) are in error, not in need of some
        sort of
        outrageous explanations to legitimize them.

        Disintegrating comets (as opposed to splitting ones) do not survive very
        long after the process has been observed to begin, which in the case with
        Comet Elenin was all the way back in the end of August. The decline/fade of
        Elenin was abrupt and dramatic. This disintegration process historically
        does not seem to leave any long-surviving fragment(s) to continue to
        a substantial post-disruption coma. In the final stages the residual coma
        would be expected to grow ever larger and exhibit a rapidly fading surface
        brightness. Comet Elenin was less than 0.3 AU from the Earth in early
        October. If any trace at all remained of the comet's coma it should have
        subtended a very larger diameter, not 6', or so, while its surface
        brightness could
        hardly have been anticipated to be as bright as the sky background.

        Similarly, as no remnant trace of the comet could be detected when within
        the FOV of various solar monitoring satellites already back in the latter
        half of September, signaling that the comet had ceased to exist, not just
        have been growing steadily fainter day by day.

        If visual comet data is to have any lasting use to researchers in the
        future it is absolutely necessary to critically evaluation the data as it is

        currently being generated to prevent erroneous observations from entering
        achieves. This should start with the observer himself, but if not the point
        should be raised by those in the observing community/archievers.
        Researchers in years to come will not be familiar with who the observers
        were, nor
        whether their observations should be taken at face value, or not, in
        situations like those surrounding a unusual cometary events. In the current
        just when Comet Elenin had fully disintegrated and dissipated would be
        critical to any analysis and potential explanation of the process. Muddying
        the waters with erroneous observations would be a great disservice to all


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