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C/2012 S1 ISON visual observation

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  • Bob King
    Hi all, I hesitated posting two nights ago but feel confident after tonight to share my observation of C/2012 S1 ISON. I observed the comet on Jan. 7.16 UT
    Message 1 of 4 , Jan 6, 2013
      Hi all,
      I hesitated posting two nights ago but feel confident after tonight to
      share my observation of C/2012 S1 ISON. I observed the comet on Jan.
      7.16 UT using a 15-inch (37cm) reflector at 257x. ISON was dead-on
      position and visible on numerous occasions with averted vision
      especially when the seeing became steady. It appeared as a 15-20"
      diameter moderately condensed object with DC=6 during the best
      moments. When steadiness deteriorated, it appeared fuzzier and not
      quite as condensed. With clouds on my heels, I swung the scope from
      ISON to the U Gem star field (AAVSO chart) to estimate its brightness.
      The comet was clearly fainter than 13.9 magnitude and close to ~14.3-4
      magnitude. If the clouds hadn't swept in so quickly, my estimate would
      be more certain. Two nights ago, ISON's appearance was similar to
      tonight's. Now all I need is a clear, steady sky for about 3 hours so
      I can confirm motion.
      Best regards,
      Bob
    • Bomber2 Panther
      Good onya Bob! :-) Hope you get those clear skies! Cheers, Chris W
      Message 2 of 4 , Jan 6, 2013
        Good onya Bob! :-)

        Hope you get those clear skies!

        Cheers,
        Chris W
        ----------------------------------------
        > To: comets-ml@yahoogroups.com
        > From: nightsky55@...
        > Date: Sun, 6 Jan 2013 22:56:11 -0600
        > Subject: [comets-ml] C/2012 S1 ISON visual observation
        >
        > Hi all,
        > I hesitated posting two nights ago but feel confident after tonight to
        > share my observation of C/2012 S1 ISON. I observed the comet on Jan.
        > 7.16 UT using a 15-inch (37cm) reflector at 257x. ISON was dead-on
        > position and visible on numerous occasions with averted vision
        > especially when the seeing became steady. It appeared as a 15-20"
        > diameter moderately condensed object with DC=6 during the best
        > moments. When steadiness deteriorated, it appeared fuzzier and not
        > quite as condensed. With clouds on my heels, I swung the scope from
        > ISON to the U Gem star field (AAVSO chart) to estimate its brightness.
        > The comet was clearly fainter than 13.9 magnitude and close to ~14.3-4
        > magnitude. If the clouds hadn't swept in so quickly, my estimate would
        > be more certain. Two nights ago, ISON's appearance was similar to
        > tonight's. Now all I need is a clear, steady sky for about 3 hours so
        > I can confirm motion.
        > Best regards,
        > Bob
        >
        >
        > ------------------------------------
        >
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        >
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        >
      • reinder j bouma
        ... Hi Bob, Great result! But you could have made life much easier on yourself if you had used comparison stars from APASS, which go down to magnitude ~17V
        Message 3 of 4 , Jan 7, 2013
          On 7-1-2013 4:56, Bob King wrote:
          > Hi all,
          > I hesitated posting two nights ago but feel confident after tonight to
          > share my observation of C/2012 S1 ISON. I observed the comet on Jan.
          > 7.16 UT using a 15-inch (37cm) reflector at 257x. ISON was dead-on
          > position and visible on numerous occasions with averted vision
          > especially when the seeing became steady. It appeared as a 15-20"
          > diameter moderately condensed object with DC=6 during the best
          > moments. When steadiness deteriorated, it appeared fuzzier and not
          > quite as condensed. With clouds on my heels, I swung the scope from
          > ISON to the U Gem star field (AAVSO chart) to estimate its brightness.
          > The comet was clearly fainter than 13.9 magnitude and close to ~14.3-4
          > magnitude. If the clouds hadn't swept in so quickly, my estimate would
          > be more certain. Two nights ago, ISON's appearance was similar to
          > tonight's. Now all I need is a clear, steady sky for about 3 hours so
          > I can confirm motion.
          > Best regards,
          > Bob
          Hi Bob,

          Great result! But you could have made life much easier on yourself if you had used comparison stars from APASS, which go down to magnitude ~17V right in the field of the comet.
          Although I do not doubt your positive observation I doubt whether this comet is already as bright as 14th magnitude. Recent CCD observations place it closer to magnitude 16V, which would still make it observable (just) for your setup, because it is so small and condensed.
          For your and other visual observer's information: I place a monthly update on my homepage for Guide8 or 9 users with selected APASS V-magnitudes (down to magnitude 15.0) along the path of comets expected to be in the magnitude 10-15 range.
          Comet 2012 S1 is not included in the most recent January file, but if anyone is interested I can prepare an update later today.

          best regards,
          Reinder

          --------------------------------------------------------------
          Reinder J. Bouma e-mail (1): rjbouma@...
          Bekemaheerd 77 e-mail (2): comets@...
          9737PR Groningen homepage: http://www.shopplaza.nl/astro/
          The Netherlands phone: +31 (0)50-5418227
          --------------------------------------------------------------
        • David Seargent
          The comet is at very small phase angle at present, so it might be experiencing a degree of brightness enhancement due to back scattering of sunlight from coma
          Message 4 of 4 , Jan 7, 2013
            The comet is at very small phase angle at present, so it might be experiencing a degree of brightness enhancement due to back scattering of sunlight from coma dust.
            Cheers,
            David




            To: comets-ml@yahoogroups.com; nightsky55@...
            From: rjbouma@...
            Date: Mon, 7 Jan 2013 10:33:03 +0000
            Subject: Re: [comets-ml] C/2012 S1 ISON visual observation





            On 7-1-2013 4:56, Bob King wrote:
            > Hi all,
            > I hesitated posting two nights ago but feel confident after tonight to
            > share my observation of C/2012 S1 ISON. I observed the comet on Jan.
            > 7.16 UT using a 15-inch (37cm) reflector at 257x. ISON was dead-on
            > position and visible on numerous occasions with averted vision
            > especially when the seeing became steady. It appeared as a 15-20"
            > diameter moderately condensed object with DC=6 during the best
            > moments. When steadiness deteriorated, it appeared fuzzier and not
            > quite as condensed. With clouds on my heels, I swung the scope from
            > ISON to the U Gem star field (AAVSO chart) to estimate its brightness.
            > The comet was clearly fainter than 13.9 magnitude and close to ~14.3-4
            > magnitude. If the clouds hadn't swept in so quickly, my estimate would
            > be more certain. Two nights ago, ISON's appearance was similar to
            > tonight's. Now all I need is a clear, steady sky for about 3 hours so
            > I can confirm motion.
            > Best regards,
            > Bob
            Hi Bob,

            Great result! But you could have made life much easier on yourself if you had used comparison stars from APASS, which go down to magnitude ~17V right in the field of the comet.
            Although I do not doubt your positive observation I doubt whether this comet is already as bright as 14th magnitude. Recent CCD observations place it closer to magnitude 16V, which would still make it observable (just) for your setup, because it is so small and condensed.
            For your and other visual observer's information: I place a monthly update on my homepage for Guide8 or 9 users with selected APASS V-magnitudes (down to magnitude 15.0) along the path of comets expected to be in the magnitude 10-15 range.
            Comet 2012 S1 is not included in the most recent January file, but if anyone is interested I can prepare an update later today.

            best regards,
            Reinder

            ----------------------------------------------------------
            Reinder J. Bouma e-mail (1): rjbouma@...
            Bekemaheerd 77 e-mail (2): comets@...
            9737PR Groningen homepage: http://www.shopplaza.nl/astro/
            The Netherlands phone: +31 (0)50-5418227
            ----------------------------------------------------------






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