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C/2006 P1 photometric behaviour.

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  • Juan Jose Gonzalez Suarez
    C/2006 P1 (McNaught): 2007 Jan. 2.30 UT: m1= 2.7*, Dia.=1.5 , DC=8, Tail: 0.1 deg. in PA 0 deg, 25x100B. [ Mountain location, clear sky. Magnitude estimate
    Message 1 of 13 , Jan 2, 2007
      C/2006 P1 (McNaught):
      2007 Jan. 2.30 UT: m1= 2.7*, Dia.=1.5', DC=8, Tail: 0.1 deg. in PA 0
      deg, 25x100B.
      [ Mountain location, clear sky. Magnitude estimate corrected for
      atmospheric extinction with ICQ winter table. Very low altitude: 3 deg;
      solar elongation: 15 deg. Short dust tail. The comet remained visible
      for 15 minutes in nautical twilight ].

      ( Alto del Castro, alt.1720 m, Leon, N. Spain)

      ------------------------------------------------
      ICQ Format:

      2006P1 2007 01 02.30 $B 2.7 TK 10.0B 25 1.5 8 0.1 0 ICQ
      XX GON05
      ------------------------------------------------


      Best Regards,

      J. J. González
      http://www.perihelio.org
    • cnj999
      ... deg; ... The circumstances of Jaun s observation point up a new problem in determining the present and immediate future brightness of P1. If indeed as
      Message 2 of 13 , Jan 2, 2007
        --- In comets-ml@yahoogroups.com, Juan Jose Gonzalez Suarez
        <jjgonzalez@...> wrote:
        >
        > C/2006 P1 (McNaught):
        > 2007 Jan. 2.30 UT: m1= 2.7*, Dia.=1.5', DC=8, Tail: 0.1 deg. in PA 0
        > deg, 25x100B.
        > [ Mountain location, clear sky. Magnitude estimate corrected for
        > atmospheric extinction with ICQ winter table. Very low altitude: 3
        deg;
        > solar elongation: 15 deg. Short dust tail. The comet remained visible
        > for 15 minutes in nautical twilight ].
        >

        The circumstances of Jaun's observation point up a new problem in
        determining the present and immediate future brightness of P1. If
        indeed as bright as +2.7 (and I have every reason to believe that this
        estimate is reasonably valid), then extinction corrections are likely
        to be extremely problematical in coming days. Being so very low over
        the eastern horizon, the only possible remaining comparison stars at a
        similar altitude to the comet's are alpha and gamma Aql and these will
        be outdistanced quickly. This means that any further brightness
        estimates will be little more than guesses, given that the extinction
        corrections will be measured in whole magnitudes!

        Thus, we now seem to be coming back to the situation facing us a week
        or two ago. This being that the comet may indeed become very brilliant
        near perihelion passage - but just how brilliant can be open to wide
        spectulation! Further, its brightness could be enhansed even more if
        forward scattering should play any significant roll.

        In regard to this, I find that the maximum potential for a forward
        scatter event occurs around January 14.25UT, when the comet's phase
        angle reaches at maximum of 149 degrees. At that time the comet is
        situated 5.6 degrees due east of the Sun and at the same time is in
        conjunction with the planet Mercury (-1.1 mag), their separation being
        less than 1 degree!

        JBortle
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