Loading ...
Sorry, an error occurred while loading the content.

RE: [comets-ml] Re: C/2011 L4 Secondary ion->DUST tail developing

Expand Messages
  • José J. Chambó
    Hi Nicolas. I think there was a ion tail on March, an unusual red tail of sodium or iron (depending on sources) that can be seen in several images, for
    Message 1 of 8 , Jun 20, 2013
    • 0 Attachment
      Hi Nicolas.
      I think there was a ion tail on March, an unusual red tail of sodium or iron (depending on sources) that can be seen in several images, for instance in a image I took on March 15:
      http://cometografia.es/2013/03/cola-roja-panstarrs/

      Regards.


      Jos� J. Chamb� (Valencia, Spain)blog: cometografia.es twitter: @PepeChambo

      To: comets-ml@yahoogroups.com
      From: Nicolas.Biver@...
      Date: Thu, 20 Jun 2013 07:41:30 +0000
      Subject: [comets-ml] Re: C/2011 L4 Secondary ion->DUST tail developing


























      Dear Dr Clay, all,



      Note that there is no (and was hardly ever - maybe slightly in Stereo images) ion tail in comet C/2011 L4 (PanSTARRS). At least I haven't seen images showing any obviously, and this can be explained by both the relatively low outgassing rate of the comet (or very high dust/gas ratio) and very low CO abundance (responsible for the blue CO+).

      But as seen in this image and others before the plane crossing the dust tail shows several structures, from the broad light dust classical tail moving away from the sun to these probably two ribbons of large (and very large?) dust particles pointing close or relatively close to the direction of the sun due to projecting effects of the orbital plane. At the time of this picture the PA of the Sun was about 316 (and opposite of motion vector 328), close to the weaker "dust ribbon" direction.



      Nicolas



      --- In comets-ml@yahoogroups.com, "P. Clay Sherrod" <drclay@...> wrote:

      >

      > Comet c/2011 L4 PANSTARRS Meets Kochab in high northern skies; note the appearance of

      > a secondary ion tail streaming northward from the comet; the main dust tail is to the

      > lower left (southeast) of the comets very bright and dense head. The magnitude of the

      > comet on this date was measured at ASO to be 11.8 (m2) and thus appears to be slowly

      > fading.

      >

      > Photo is cropped to about 86 arc minutes with north up. Two 120s exposures, STF8300

      > w/11cm f/4.9 APO, June 19, 09:10 UT

      >

      > http://www.arksky.org/smf/index.php/topic,2148.msg9976.html

      >

      > 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/

      >



















      [Non-text portions of this message have been removed]
    • biver_nicolas
      Yes, there was a non-dust tail in march when the comet was close to the Sun (
      Message 2 of 8 , Jun 21, 2013
      • 0 Attachment
        Yes, there was a non-dust tail in march when the comet was close to the Sun ( << 1 AU), but Na or Fe atoms are not ions and do not interact with solar wind, and likely do not come from gas but from thermal degradation of grains, or... (we don't know exactly) and can only be seen very close to the Sun when high temperature enable release of such atoms.
        Otherwise it is not yet clear whether this tail is made of Fe or Na atoms. Na is for sure present but would look yellow, while for Fe it is less clear which lines would contribute... optical spectroscopy would have helped - be prepared for ISON!

        Nicolas

        --- In comets-ml@yahoogroups.com, José J. Chambó <jjchambo@...> wrote:
        >
        > Hi Nicolas.
        > I think there was a ion tail on March, an unusual red tail of sodium or iron (depending on sources) that can be seen in several images, for instance in a image I took on March 15:
        > http://cometografia.es/2013/03/cola-roja-panstarrs/
        >
        > Regards.
        >
        >
        > José J. Chambó (Valencia, Spain)blog: cometografia.es twitter: @PepeChambo
        >
        > To: comets-ml@yahoogroups.com
        > From: Nicolas.Biver@...
        > Date: Thu, 20 Jun 2013 07:41:30 +0000
        > Subject: [comets-ml] Re: C/2011 L4 Secondary ion->DUST tail developing
        >
        >
        >
        >
        >
        >
        >
        >
        >
        >
        >
        >
        >
        >
        >
        >
        >
        >
        >
        >
        >
        >
        >
        >
        >
        >
        > Dear Dr Clay, all,
        >
        >
        >
        > Note that there is no (and was hardly ever - maybe slightly in Stereo images) ion tail in comet C/2011 L4 (PanSTARRS). At least I haven't seen images showing any obviously, and this can be explained by both the relatively low outgassing rate of the comet (or very high dust/gas ratio) and very low CO abundance (responsible for the blue CO+).
        >
        > But as seen in this image and others before the plane crossing the dust tail shows several structures, from the broad light dust classical tail moving away from the sun to these probably two ribbons of large (and very large?) dust particles pointing close or relatively close to the direction of the sun due to projecting effects of the orbital plane. At the time of this picture the PA of the Sun was about 316 (and opposite of motion vector 328), close to the weaker "dust ribbon" direction.
        >
        >
        >
        > Nicolas
        >
        >
        >
        > --- In comets-ml@yahoogroups.com, "P. Clay Sherrod" <drclay@> wrote:
        >
        > >
        >
        > > Comet c/2011 L4 PANSTARRS Meets Kochab in high northern skies; note the appearance of
        >
        > > a secondary ion tail streaming northward from the comet; the main dust tail is to the
        >
        > > lower left (southeast) of the comets very bright and dense head. The magnitude of the
        >
        > > comet on this date was measured at ASO to be 11.8 (m2) and thus appears to be slowly
        >
        > > fading.
        >
        > >
        >
        > > Photo is cropped to about 86 arc minutes with north up. Two 120s exposures, STF8300
        >
        > > w/11cm f/4.9 APO, June 19, 09:10 UT
        >
        > >
        >
        > > http://www.arksky.org/smf/index.php/topic,2148.msg9976.html
        >
        > >
        >
        > > 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/
        >
        > >
        >
        >
        >
        >
        >
        >
        >
        >
        >
        >
        >
        >
        >
        >
        >
        >
        >
        >
        >
        > [Non-text portions of this message have been removed]
        >
      • Michal Drahus
        This red tail might have been also made of H2O+, which emits around 700 nm. In fact, this type of an ion tail was observed in some comets before. Michal
        Message 3 of 8 , Jun 21, 2013
        • 0 Attachment
          This red tail might have been also made of H2O+, which emits around 700
          nm. In fact, this type of an ion tail was observed in some comets before.

          Michal


          > Yes, there was a non-dust tail in march when the comet was close to the
          > Sun ( << 1 AU), but Na or Fe atoms are not ions and do not interact with
          > solar wind, and likely do not come from gas but from thermal degradation
          > of grains, or... (we don't know exactly) and can only be seen very close
          > to the Sun when high temperature enable release of such atoms.
          > Otherwise it is not yet clear whether this tail is made of Fe or Na atoms.
          > Na is for sure present but would look yellow, while for Fe it is less
          > clear which lines would contribute... optical spectroscopy would have
          > helped - be prepared for ISON!
          >
          > Nicolas
          >
          > --- In comets-ml@yahoogroups.com, José J. Chambó <jjchambo@...> wrote:
          >>
          >> Hi Nicolas.
          >> I think there was a ion tail on March, an unusual red tail of sodium or
          >> iron (depending on sources) that can be seen in several images, for
          >> instance in a image I took on March 15:
          >> http://cometografia.es/2013/03/cola-roja-panstarrs/
          >>
          >> Regards.
          >>
          >>
          >> José J. Chambó (Valencia, Spain)blog: cometografia.es twitter:
          >> @PepeChambo
          >>
          >> To: comets-ml@yahoogroups.com
          >> From: Nicolas.Biver@...
          >> Date: Thu, 20 Jun 2013 07:41:30 +0000
          >> Subject: [comets-ml] Re: C/2011 L4 Secondary ion->DUST tail developing
          >>
          >>
          >>
          >>
          >>
          >>
          >>
          >>
          >>
          >>
          >>
          >>
          >>
          >>
          >>
          >>
          >>
          >>
          >>
          >>
          >>
          >>
          >>
          >>
          >>
          >>
          >> Dear Dr Clay, all,
          >>
          >>
          >>
          >> Note that there is no (and was hardly ever - maybe slightly in Stereo
          >> images) ion tail in comet C/2011 L4 (PanSTARRS). At least I haven't seen
          >> images showing any obviously, and this can be explained by both the
          >> relatively low outgassing rate of the comet (or very high dust/gas
          >> ratio) and very low CO abundance (responsible for the blue CO+).
          >>
          >> But as seen in this image and others before the plane crossing the dust
          >> tail shows several structures, from the broad light dust classical tail
          >> moving away from the sun to these probably two ribbons of large (and
          >> very large?) dust particles pointing close or relatively close to the
          >> direction of the sun due to projecting effects of the orbital plane. At
          >> the time of this picture the PA of the Sun was about 316 (and opposite
          >> of motion vector 328), close to the weaker "dust ribbon" direction.
          >>
          >>
          >>
          >> Nicolas
          >>
          >>
          >>
          >> --- In comets-ml@yahoogroups.com, "P. Clay Sherrod" <drclay@> wrote:
          >>
          >> >
          >>
          >> > Comet c/2011 L4 PANSTARRS Meets Kochab in high northern skies; note
          >> the appearance of
          >>
          >> > a secondary ion tail streaming northward from the comet; the main dust
          >> tail is to the
          >>
          >> > lower left (southeast) of the comets very bright and dense head. The
          >> magnitude of the
          >>
          >> > comet on this date was measured at ASO to be 11.8 (m2) and thus
          >> appears to be slowly
          >>
          >> > fading.
          >>
          >> >
          >>
          >> > Photo is cropped to about 86 arc minutes with north up. Two 120s
          >> exposures, STF8300
          >>
          >> > w/11cm f/4.9 APO, June 19, 09:10 UT
          >>
          >> >
          >>
          >> > http://www.arksky.org/smf/index.php/topic,2148.msg9976.html
          >>
          >> >
          >>
          >> > 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/
          >>
          >> >
          >>
          >>
          >>
          >>
          >>
          >>
          >>
          >>
          >>
          >>
          >>
          >>
          >>
          >>
          >>
          >>
          >>
          >>
          >>
          >> [Non-text portions of this message have been removed]
          >>
          >
          >
          >
        • Rob
          There was definitely a strong sodium emission in the coma and main dust tail at the start of March, per low-res spectrum obtained 01 March 2013:
          Message 4 of 8 , Jun 22, 2013
          • 0 Attachment
            There was definitely a strong sodium emission in the coma and main dust tail at the start of March, per low-res spectrum obtained 01 March 2013:
            http://i727.photobucket.com/albums/ww271/Rob_Kau/Sodiumtail.jpg
            http://i727.photobucket.com/albums/ww271/Rob_Kau/Panst-Lemmspectra28Feb01Mar2013.jpg

            Whether that could have been 'isolated' later by changing geometry, maybe someone can comment. It was out of my (southern) view at that stage.

            Cheers -

            Rob Kaufman
            Bright, Victoria, Australia


            --- In comets-ml@yahoogroups.com, "Michal Drahus" <mdrahus@...> wrote:
            >
            > This red tail might have been also made of H2O+, which emits around 700
            > nm. In fact, this type of an ion tail was observed in some comets before.
            >
            > Michal
            >
            >
            > > Yes, there was a non-dust tail in march when the comet was close to the
            > > Sun ( << 1 AU), but Na or Fe atoms are not ions and do not interact with
            > > solar wind, and likely do not come from gas but from thermal degradation
            > > of grains, or... (we don't know exactly) and can only be seen very close
            > > to the Sun when high temperature enable release of such atoms.
            > > Otherwise it is not yet clear whether this tail is made of Fe or Na atoms.
            > > Na is for sure present but would look yellow, while for Fe it is less
            > > clear which lines would contribute... optical spectroscopy would have
            > > helped - be prepared for ISON!
            > >
            > > Nicolas
            > >
            > > --- In comets-ml@yahoogroups.com, José J. Chambó <jjchambo@> wrote:
            > >>
            > >> Hi Nicolas.
            > >> I think there was a ion tail on March, an unusual red tail of sodium or
            > >> iron (depending on sources) that can be seen in several images, for
            > >> instance in a image I took on March 15:
            > >> http://cometografia.es/2013/03/cola-roja-panstarrs/
            > >>
            > >> Regards.
            > >>
            > >>
            > >> José J. Chambó (Valencia, Spain)blog: cometografia.es twitter:
            > >> @PepeChambo
            > >>
            > >> To: comets-ml@yahoogroups.com
            > >> From: Nicolas.Biver@
            > >> Date: Thu, 20 Jun 2013 07:41:30 +0000
            > >> Subject: [comets-ml] Re: C/2011 L4 Secondary ion->DUST tail developing
            > >>
            > >>
            > >>
            > >>
            > >>
            > >>
            > >>
            > >>
            > >>
            > >>
            > >>
            > >>
            > >>
            > >>
            > >>
            > >>
            > >>
            > >>
            > >>
            > >>
            > >>
            > >>
            > >>
            > >>
            > >>
            > >>
            > >> Dear Dr Clay, all,
            > >>
            > >>
            > >>
            > >> Note that there is no (and was hardly ever - maybe slightly in Stereo
            > >> images) ion tail in comet C/2011 L4 (PanSTARRS). At least I haven't seen
            > >> images showing any obviously, and this can be explained by both the
            > >> relatively low outgassing rate of the comet (or very high dust/gas
            > >> ratio) and very low CO abundance (responsible for the blue CO+).
            > >>
            > >> But as seen in this image and others before the plane crossing the dust
            > >> tail shows several structures, from the broad light dust classical tail
            > >> moving away from the sun to these probably two ribbons of large (and
            > >> very large?) dust particles pointing close or relatively close to the
            > >> direction of the sun due to projecting effects of the orbital plane. At
            > >> the time of this picture the PA of the Sun was about 316 (and opposite
            > >> of motion vector 328), close to the weaker "dust ribbon" direction.
            > >>
            > >>
            > >>
            > >> Nicolas
            > >>
            > >>
            > >>
            > >> --- In comets-ml@yahoogroups.com, "P. Clay Sherrod" <drclay@> wrote:
            > >>
            > >> >
            > >>
            > >> > Comet c/2011 L4 PANSTARRS Meets Kochab in high northern skies; note
            > >> the appearance of
            > >>
            > >> > a secondary ion tail streaming northward from the comet; the main dust
            > >> tail is to the
            > >>
            > >> > lower left (southeast) of the comets very bright and dense head. The
            > >> magnitude of the
            > >>
            > >> > comet on this date was measured at ASO to be 11.8 (m2) and thus
            > >> appears to be slowly
            > >>
            > >> > fading.
            > >>
            > >> >
            > >>
            > >> > Photo is cropped to about 86 arc minutes with north up. Two 120s
            > >> exposures, STF8300
            > >>
            > >> > w/11cm f/4.9 APO, June 19, 09:10 UT
            > >>
            > >> >
            > >>
            > >> > http://www.arksky.org/smf/index.php/topic,2148.msg9976.html
            > >>
            > >> >
            > >>
            > >> > 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/
            > >>
            > >> >
            > >>
            > >>
            > >>
            > >>
            > >>
            > >>
            > >>
            > >>
            > >>
            > >>
            > >>
            > >>
            > >>
            > >>
            > >>
            > >>
            > >>
            > >>
            > >>
            > >> [Non-text portions of this message have been removed]
            > >>
            > >
            > >
            > >
            >
          • David Seargent
            I think that a tail of this type (H2O+)was seen in images of P/Crommelin in 1984, albeit at much larger solar distances than the red tail of L4. Regards,
            Message 5 of 8 , Jun 22, 2013
            • 0 Attachment
              I think that a tail of this type (H2O+)was seen in images of P/Crommelin in 1984, albeit at much larger solar distances than the "red" tail of L4.

              Regards,

              David Seargent




              To: comets-ml@yahoogroups.com
              From: mdrahus@...
              Date: Fri, 21 Jun 2013 21:38:50 -0700
              Subject: Re: [comets-ml] Re: C/2011 L4 Secondary ion->DUST tail developing





              This red tail might have been also made of H2O+, which emits around 700
              nm. In fact, this type of an ion tail was observed in some comets before.

              Michal

              > Yes, there was a non-dust tail in march when the comet was close to the
              > Sun ( << 1 AU), but Na or Fe atoms are not ions and do not interact with
              > solar wind, and likely do not come from gas but from thermal degradation
              > of grains, or... (we don't know exactly) and can only be seen very close
              > to the Sun when high temperature enable release of such atoms.
              > Otherwise it is not yet clear whether this tail is made of Fe or Na atoms.
              > Na is for sure present but would look yellow, while for Fe it is less
              > clear which lines would contribute... optical spectroscopy would have
              > helped - be prepared for ISON!
              >
              > Nicolas
              >
              > --- In comets-ml@yahoogroups.com, Jos� J. Chamb� <jjchambo@...> wrote:
              >>
              >> Hi Nicolas.
              >> I think there was a ion tail on March, an unusual red tail of sodium or
              >> iron (depending on sources) that can be seen in several images, for
              >> instance in a image I took on March 15:
              >> http://cometografia.es/2013/03/cola-roja-panstarrs/
              >>
              >> Regards.
              >>
              >>
              >> Jos� J. Chamb� (Valencia, Spain)blog: cometografia.es twitter:
              >> @PepeChambo
              >>
              >> To: comets-ml@yahoogroups.com
              >> From: Nicolas.Biver@...
              >> Date: Thu, 20 Jun 2013 07:41:30 +0000
              >> Subject: [comets-ml] Re: C/2011 L4 Secondary ion->DUST tail developing
              >>
              >>
              >>
              >>
              >>
              >>
              >>
              >>
              >>
              >>
              >>
              >>
              >>
              >>
              >>
              >>
              >>
              >>
              >>
              >>
              >>
              >>
              >>
              >>
              >>
              >>
              >> Dear Dr Clay, all,
              >>
              >>
              >>
              >> Note that there is no (and was hardly ever - maybe slightly in Stereo
              >> images) ion tail in comet C/2011 L4 (PanSTARRS). At least I haven't seen
              >> images showing any obviously, and this can be explained by both the
              >> relatively low outgassing rate of the comet (or very high dust/gas
              >> ratio) and very low CO abundance (responsible for the blue CO+).
              >>
              >> But as seen in this image and others before the plane crossing the dust
              >> tail shows several structures, from the broad light dust classical tail
              >> moving away from the sun to these probably two ribbons of large (and
              >> very large?) dust particles pointing close or relatively close to the
              >> direction of the sun due to projecting effects of the orbital plane. At
              >> the time of this picture the PA of the Sun was about 316 (and opposite
              >> of motion vector 328), close to the weaker "dust ribbon" direction.
              >>
              >>
              >>
              >> Nicolas
              >>
              >>
              >>
              >> --- In comets-ml@yahoogroups.com, "P. Clay Sherrod" <drclay@> wrote:
              >>
              >> >
              >>
              >> > Comet c/2011 L4 PANSTARRS Meets Kochab in high northern skies; note
              >> the appearance of
              >>
              >> > a secondary ion tail streaming northward from the comet; the main dust
              >> tail is to the
              >>
              >> > lower left (southeast) of the comets very bright and dense head. The
              >> magnitude of the
              >>
              >> > comet on this date was measured at ASO to be 11.8 (m2) and thus
              >> appears to be slowly
              >>
              >> > fading.
              >>
              >> >
              >>
              >> > Photo is cropped to about 86 arc minutes with north up. Two 120s
              >> exposures, STF8300
              >>
              >> > w/11cm f/4.9 APO, June 19, 09:10 UT
              >>
              >> >
              >>
              >> > http://www.arksky.org/smf/index.php/topic,2148.msg9976.html
              >>
              >> >
              >>
              >> > 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/
              >>
              >> >
              >>
              >>
              >>
              >>
              >>
              >>
              >>
              >>
              >>
              >>
              >>
              >>
              >>
              >>
              >>
              >>
              >>
              >>
              >>
              >> [Non-text portions of this message have been removed]
              >>
              >
              >
              >







              [Non-text portions of this message have been removed]
            • Michal Drahus
              More recently in, for example, comet Wirtanen: http://sci.esa.int/rosetta/12176-comet-wirtanen/ Michal
              Message 6 of 8 , Jun 22, 2013
              • 0 Attachment
                More recently in, for example, comet Wirtanen:
                http://sci.esa.int/rosetta/12176-comet-wirtanen/

                Michal


                > I think that a tail of this type (H2O+)was seen in images of P/Crommelin
                > in 1984, albeit at much larger solar distances than the "red" tail of L4.
                >
                > Regards,
                >
                > David Seargent
                >
                >
                >
                >
                > To: comets-ml@yahoogroups.com
                > From: mdrahus@...
                > Date: Fri, 21 Jun 2013 21:38:50 -0700
                > Subject: Re: [comets-ml] Re: C/2011 L4 Secondary ion->DUST tail developing
                >
                >
                >
                >
                >
                > This red tail might have been also made of H2O+, which emits around 700
                > nm. In fact, this type of an ion tail was observed in some comets before.
                >
                > Michal
                >
                >> Yes, there was a non-dust tail in march when the comet was close to the
                >> Sun ( << 1 AU), but Na or Fe atoms are not ions and do not interact with
                >> solar wind, and likely do not come from gas but from thermal degradation
                >> of grains, or... (we don't know exactly) and can only be seen very close
                >> to the Sun when high temperature enable release of such atoms.
                >> Otherwise it is not yet clear whether this tail is made of Fe or Na
                >> atoms.
                >> Na is for sure present but would look yellow, while for Fe it is less
                >> clear which lines would contribute... optical spectroscopy would have
                >> helped - be prepared for ISON!
                >>
                >> Nicolas
                >>
                >> --- In comets-ml@yahoogroups.com, José J. Chambó <jjchambo@...> wrote:
                >>>
                >>> Hi Nicolas.
                >>> I think there was a ion tail on March, an unusual red tail of sodium or
                >>> iron (depending on sources) that can be seen in several images, for
                >>> instance in a image I took on March 15:
                >>> http://cometografia.es/2013/03/cola-roja-panstarrs/
                >>>
                >>> Regards.
                >>>
                >>>
                >>> José J. Chambó (Valencia, Spain)blog: cometografia.es twitter:
                >>> @PepeChambo
                >>>
                >>> To: comets-ml@yahoogroups.com
                >>> From: Nicolas.Biver@...
                >>> Date: Thu, 20 Jun 2013 07:41:30 +0000
                >>> Subject: [comets-ml] Re: C/2011 L4 Secondary ion->DUST tail developing
                >>>
                >>>
                >>>
                >>>
                >>>
                >>>
                >>>
                >>>
                >>>
                >>>
                >>>
                >>>
                >>>
                >>>
                >>>
                >>>
                >>>
                >>>
                >>>
                >>>
                >>>
                >>>
                >>>
                >>>
                >>>
                >>>
                >>> Dear Dr Clay, all,
                >>>
                >>>
                >>>
                >>> Note that there is no (and was hardly ever - maybe slightly in Stereo
                >>> images) ion tail in comet C/2011 L4 (PanSTARRS). At least I haven't
                >>> seen
                >>> images showing any obviously, and this can be explained by both the
                >>> relatively low outgassing rate of the comet (or very high dust/gas
                >>> ratio) and very low CO abundance (responsible for the blue CO+).
                >>>
                >>> But as seen in this image and others before the plane crossing the dust
                >>> tail shows several structures, from the broad light dust classical tail
                >>> moving away from the sun to these probably two ribbons of large (and
                >>> very large?) dust particles pointing close or relatively close to the
                >>> direction of the sun due to projecting effects of the orbital plane. At
                >>> the time of this picture the PA of the Sun was about 316 (and opposite
                >>> of motion vector 328), close to the weaker "dust ribbon" direction.
                >>>
                >>>
                >>>
                >>> Nicolas
                >>>
                >>>
                >>>
                >>> --- In comets-ml@yahoogroups.com, "P. Clay Sherrod" <drclay@> wrote:
                >>>
                >>> >
                >>>
                >>> > Comet c/2011 L4 PANSTARRS Meets Kochab in high northern skies; note
                >>> the appearance of
                >>>
                >>> > a secondary ion tail streaming northward from the comet; the main
                >>> dust
                >>> tail is to the
                >>>
                >>> > lower left (southeast) of the comets very bright and dense head. The
                >>> magnitude of the
                >>>
                >>> > comet on this date was measured at ASO to be 11.8 (m2) and thus
                >>> appears to be slowly
                >>>
                >>> > fading.
                >>>
                >>> >
                >>>
                >>> > Photo is cropped to about 86 arc minutes with north up. Two 120s
                >>> exposures, STF8300
                >>>
                >>> > w/11cm f/4.9 APO, June 19, 09:10 UT
                >>>
                >>> >
                >>>
                >>> > http://www.arksky.org/smf/index.php/topic,2148.msg9976.html
                >>>
                >>> >
                >>>
                >>> > 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/
                >>>
                >>> >
                >>>
                >>>
                >>>
                >>>
                >>>
                >>>
                >>>
                >>>
                >>>
                >>>
                >>>
                >>>
                >>>
                >>>
                >>>
                >>>
                >>>
                >>>
                >>>
                >>> [Non-text portions of this message have been removed]
                >>>
                >>
                >>
                >>
                >
                >
                >
                >
                >
                >
                >
                > [Non-text portions of this message have been removed]
                >
                >
                >
                > ------------------------------------
                >
                > *** Comets Mailing List Important Contributions : ***
                > ***
                > http://tech.groups.yahoo.com/group/comets-ml/files/Important%20Contributions/
                > ***
                >
                > Comet Observations List: http://groups.yahoo.com/group/CometObs/
                > Comet Images List: http://groups.yahoo.com/group/Comet-Images/
                >
                > NOTICE: Material quoted or re-posted from the Comets Mailing List should
                > be indicated by:
                >
                > Comets Mailing List [date]
                > http://www.yahoogroups.com/group/comets-ml
                > Yahoo! Groups Links
                >
                >
                >
              Your message has been successfully submitted and would be delivered to recipients shortly.