HIGH%20RESOLUTION%20SOLAR%20OBSERVATIONS%20USING%20COMMERCIAL%20FILTERS%20AND%20SMALL%20APERTURE%20TELESCOPES

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HIGH RESOLUTION SOLAR OBSERVATIONS USING
COMMERCIAL FILTERS AND SMALL APERTURE
TELESCOPES Patrick Stoker
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BASIC FILTER TYPES

• FRONT MOUNTED FILTERS
• CORONADO Ha CaK
• SOLARSCOPE Ha
• Type of filter used by most amateurs
• 98 use the Coronado Filters due to availability
  and price
• Available as either a 0.7Å or a 0.5Å bandpass
  filter
• Both Companies use a tilt tuner at the back of
  the etalon for viewing some types of Doppler
  shifts and to facilitate tuning
• Both filters are a Fabry-Perot design centered at
  656.28nm but neither are designed for viewing in
  the wings of H-alpha
• Etalon design of Coronado filters uses a spacer
  which creates a central obstruction of 2 to 5.
  Solarscope filters are a classic Fabry-Perot
  airspace design with a clear aperture and no
  central obstruction
• Used with small aperture and short focal length
  refractors
• Effective focal length increased with barlows

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• REAR MOUNTED FILTERS
• DAYSTAR Ha, CaK, CaH Sodium D
• SOLAR SPECTRUM Ha, CaK All Visible Light
• Most amateurs purchase the H-alpha filters in
  bandwidths of 0.3Å to 0.8Å
• Filters can be moved off band about 1Å into the
  wings of H-alpha
• Used with larger 4 to 6aperture refractors, f/8
  or slower
• Effective focal length increased with
  telecentrics
• WHITE LIGHT FILTERS
• Only used to observe the Photosphere
• FILM OR GLASS
• Type used by most amateurs. Can be used on any
  type of telescope
• HERSCHEL WEDGE
• Considered dangerous in the past, however new
  safety features have been added
• Can only be used with a refractor telescope

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CAMERAS

• HIGH SPEED IMAGING CAMERAS - UP TO 60 fps
• Camera of choice for most who are imaging the
  planets, moon and sun because it helps overcome
  the effects of poor seeing conditions. Cameras
  that fall into this classification include
• -Lumenera DMK High Speed Cameras 60
  fps
• -Modified Web Cams 5 to 10 fps
• -Monochrome Video Cameras 30 interlaced
  fps
• COOLED CCD CAMERAS Best choice for steady
  seeing need at least 1/1000 sec exposure
  capability
• DSLR AND FIXED LENS DIGITAL CAMERAS

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IMAGE PROCESSINGHow do you get from something
like this
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To something like this?
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CONCLUDING REMARKS

• MANY AMATEURS AROUND THE WORLD CURRENTLY TAKING
  DAILY HIGH RESOLUTION SOLAR IMAGES, AND ALSO NEW
  AMATEURS STARTING TO CONCENTRATE EXCLUSIVELY ON
  THIS AREA OF ASTRONOMY
• RESULT IS AN EXISTING AS WELL AS AN EXPANDING
  RESOURCE FOR HIGH QUALITY PHOTOGRAPHIC SOLAR DATA
• CREATES AN OPPORTUNITY TO ACCUMULATE DATA THAT
  CAN BE USED FOR RESEARCH, BUT CURRENTLY THERE IS
  NO MECHANISM IN PLACE TO TAKE ADVANTAGE OF THIS
  OPPORTUNITY. ANY INITIATIVE TO CAPITALIZE ON
  THIS WILL HAVE TO COME FROM THE PROFESSIONAL
  RESEARCH COMMUNITY.