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Re: [vsx-dis] Suitable filters to use

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  • Patrick Wils
    Hi David, LRGB filters are difficult to transform to the standard photometric system, especially for red stars such as this one.  It would be better to use
    Message 1 of 5 , Jun 10, 2013
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      Hi David,


      LRGB filters are difficult to transform to the standard photometric system, especially for red stars such as this one.  It would be better to use e.g. Johnson-Cousins filters.

      As this forum has been inactive and most questions are dealt with on one of the AAVSO forums <http://www.aavso.org/forum>, I suggest to ask your questions there.  There are many more experienced photometrists available to give you more complete advice.


      Patrick

      ________________________________
      From: David Kennedy <dken@...>
      To: vsx-dis@yahoogroups.com
      Sent: Sunday, June 9, 2013 3:07 PM
      Subject: [vsx-dis] Suitable filters to use

      Hello everyone,

      I’m a new member to the group, joining after noticing a possible variable
      star in my CCD images of the nebula NGC6559.  Through the VSX website I’ve
      found out the star is a suspected variable listed as NSV 10242.  I’ve made
      observations of the star on 3 nights over the past 3.5 weeks and using MaxIm DL
      have measured that it’s decreasing in brightness.  However, I’ve been
      collecting data using the filters I use for imaging (LRGB  and Ha
      Astronomik filters) and I would like to know if useful photometric data can been
      gained with these or do I need to use different filters instead?  Can
      anyone help?

      Thanks,

      David Kennedy
    • David Kennedy
      Hi everyone, thank you for replying to my questions. Most of my data for NSV 10242 is with a Ha 12nm astronomik filter, with blue or green filters the star
      Message 2 of 5 , Jun 12, 2013
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        Hi everyone,
         
        thank you  for replying to my questions.  Most of my data for NSV 10242 is with a Ha 12nm astronomik filter, with blue or green filters the star is hardly visible. For an extreme red star which photometric filter would be most useful for making observations?.
         
        Thanks,
         
        David
         
         
         
         
        Sent: Tuesday, June 11, 2013 6:36 AM
        Subject: Re: [vsx-dis] Suitable filters to use
         
         

        Hi David,

        LRGB filters are difficult to transform to the standard photometric system, especially for red stars such as this one.  It would be better to use e.g. Johnson-Cousins filters.

        As this forum has been inactive and most questions are dealt with on one of the AAVSO forums <http://www.aavso.org/forum>, I suggest to ask your questions there.  There are many more experienced photometrists available to give you more complete advice.

        Patrick

        ________________________________
        From: David Kennedy <mailto:dken%40live.com.au>
        To: mailto:vsx-dis%40yahoogroups.com
        Sent: Sunday, June 9, 2013 3:07 PM
        Subject: [vsx-dis] Suitable filters to use

        Hello everyone,

        I’m a new member to the group, joining after noticing a possible variable
        star in my CCD images of the nebula NGC6559.  Through the VSX website I’ve
        found out the star is a suspected variable listed as NSV 10242.  I’ve made
        observations of the star on 3 nights over the past 3.5 weeks and using MaxIm DL
        have measured that it’s decreasing in brightness.  However, I’ve been
        collecting data using the filters I use for imaging (LRGB  and Ha
        Astronomik filters) and I would like to know if useful photometric data can been
        gained with these or do I need to use different filters instead?  Can
        anyone help?

        Thanks,

        David Kennedy

      • arne
        Hi David, Johnson V is almost always your first choice for photometric filters, as the next star you observe may be a different color and V is very generic.
        Message 3 of 5 , Jun 12, 2013
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          Hi David,
          Johnson V is almost always your first choice for photometric filters, as the
          next star you observe may be a different color and V is very generic. You may
          have to expose longer for your current red star, but you do that for deep-sky
          images anyway and scientific photometry always takes about the same amount of
          on-sky time. If you only want to image very red stars, your best filter is
          Cousins Ic, which is a very red filter (redder than Halpha).
          Arne

          On 6/12/13 11:52 AM, David Kennedy wrote:
          >
          >
          > Hi everyone,
          > thank you for replying to my questions. Most of my data for NSV 10242 is with
          > a Ha 12nm astronomik filter, with blue or green filters the star is hardly
          > visible. For an extreme red star which photometric filter would be most useful
          > for making observations?.
          > Thanks,
          > David
          > *From:* Patrick Wils <mailto:patrickwils@...>
          > *Sent:* Tuesday, June 11, 2013 6:36 AM
          > *To:* vsx-dis@yahoogroups.com <mailto:vsx-dis@yahoogroups.com>
          > *Subject:* Re: [vsx-dis] Suitable filters to use
          >
          > Hi David,
          >
          > LRGB filters are difficult to transform to the standard photometric system,
          > especially for red stars such as this one. It would be better to use e.g.
          > Johnson-Cousins filters.
          >
          > As this forum has been inactive and most questions are dealt with on one of the
          > AAVSO forums <http://www.aavso.org/forum>, I suggest to ask your questions
          > there. There are many more experienced photometrists available to give you more
          > complete advice.
          >
          > Patrick
          >
          > ________________________________
          > From: David Kennedy <mailto:dken%40live.com.au>
          > To: mailto:vsx-dis%40yahoogroups.com
          > Sent: Sunday, June 9, 2013 3:07 PM
          > Subject: [vsx-dis] Suitable filters to use
          >
          > Hello everyone,
          >
          > I’m a new member to the group, joining after noticing a possible variable
          > star in my CCD images of the nebula NGC6559. Through the VSX website I’ve
          > found out the star is a suspected variable listed as NSV 10242. I’ve made
          > observations of the star on 3 nights over the past 3.5 weeks and using MaxIm DL
          > have measured that it’s decreasing in brightness. However, I’ve been
          > collecting data using the filters I use for imaging (LRGB and Ha
          > Astronomik filters) and I would like to know if useful photometric data can been
          > gained with these or do I need to use different filters instead? Can
          > anyone help?
          >
          > Thanks,
          >
          > David Kennedy
          >
          >
          >
          >
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