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Re: [comets-ml] comet C/2012 S1 ISON today

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  • P. Clay Sherrod
    An interesting (and continuing) aspect of c2012 S1 is that it is not changing much at all, morphologically speaking. At close to the same time this image was
    Message 1 of 3 , Apr 30, 2013
      An interesting (and continuing) aspect of c2012 S1 is that it is not changing much at
      all, morphologically speaking.
      At close to the same time this image was taken we measured (12 measurements, April 29
      and April 30 UT) the comet (Arkansas Sky Observatories, H45), using diaphragm
      adjusted aperture via CCD and UCAC-4 star calibration, at still only 15.9-16.0 (m1);
      the measurements were slightly variable since the comet is now so low in the NW skies
      and subject to refractive interference from moment to moment.

      Thus, in terms of brightness, the comet reached a plateau back in early March of 15.8
      to 16.0 and pretty much remains there. Likewise the overall diameter and tail extent
      remains unchanged as well.

      The coma overall is still measured at a fairly consistent 10-11" arc with about an
      18" length tail, these measurements virtually unchanged and non-increasing during the
      past five weeks or more. A more pronounced stellar condensation is now seen within
      the small coma, but other than that the tail, coma and brightness characteristics
      remain unchanged in a very long period of time.

      Based on current elements, the comet should have a total brightness of about 14.9;
      This lack of physical development can be only partially attributable to orbital angle
      and phase considerations.....the comet is simply not developing as hoped at this
      time.

      Clay
      _____
      Dr. P. Clay Sherrod
      Arkansas Sky Observatories
      MPC H45 - Petit Jean Mountain South
      MPC H41 - Petit Jean Mountain
      MPC H43 - Conway West
      http://www.arksky.org/


      ----- Original Message -----
      From: "ligustri rolando" <rolando.ligustri@...>
      To: "cometas" <Observadores_cometas@yahoogroups.com>; "comet images"
      <comet-images@yahoogroups.com>; "comets-ml" <comets-ml@yahoogroups.com>
      Sent: Tuesday, April 30, 2013 1:34 PM
      Subject: [comets-ml] comet C/2012 S1 ISON today


      > http://spaceweather.com/gallery/indiv_upload.php?upload_id=81314
      >
      > regards
      > Rolando Ligustri
      >
      >
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