Recent discoveries and projects in Amateur Variable Star Astronomy

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Recent discoveries and projects in Amateur
Variable Star Astronomy

• Chris Allen
• Strawberry Fields Observatory
• Färjestaden

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Contents

• Some recent amateur discoveries
• Some pro-am projects
• The way ahead- visual or CCD?

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AAVSO / BAAVSS Meeting Cambridge April 2008
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Recent discoveries and projects

• Tagos object in Cassiopeia- a suspected
  gravitational microlensing event
• Gregr Duszanowiczs supernova discoveries
• The OJ 287 project- observations of a
  supermassive binary black hole
• Arto Oksanens discovery of the gamma ray burst
  afterglow GR071010B
• Surveys of cataclysmic variables (CVs) in the
  Hamburg Quasar Survey and Sloan Digital Sky
  Survey (SDSS)
• Remote observing

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Tagos object in Cassiopeia (2006)
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Tagos object- a relatively close microlensing
event

• magnitude
• spectral changes

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Possible explanation

• (adapted from S T 2008 July)

Star GSC 3656-1328
Massive object
Gravity focuses stars light viewed from the Earth
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OJ 287-pro am project to observe a binary black
hole
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OJ 287- a binary black hole
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OJ 287 Light curve (courtesy Gary Poyner)
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Arto Oksanens gamma ray burst afterglow

• Detection of optical transient (afterglow) of
  GRB071010B only 17 minutes after detection by the
  Swift satellite

(www.ursa.fi)
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Surveys of Cataclysmic Variables

• CVs novae, dwarf novae,nova-like variables etc
• CVs are all interacting binary systems involving
  a white dwarf and a main sequence / red giant
  companion
• Project to observe fainter CVs detected in
  Hamburg Quasar Survey, Sloan Digital Sky Survey
  etc
• Determine type of CV (eg polar, U Gem etc)
• Watch for outbursts (visual)
• Detailed analysis of lightcurve from CCD data

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CV surveys- pro-am cooperation

• Professionals supervise projects, outline goals,
  select objects
• Amateurs have the telescopes and the time (?) to
  collect the data

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Remote observing of variable stars

• Bradford Robotic Telescope
• Remote Astronomical Society instruments in New
  Mexico, Australia and Israel

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The future of amateur variable star astronomy

• In an age of CCD cameras, image processing and
  digital sky surveys, is there still a place for
  the visual observer?

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CCD imaging

• Pros
• Accuracy to 0.01 magnitude possible using
  filters
• Permanent record
• Preferred by professional astronomers
• Cons
• Expense of equipment (CCD camera equatorial
  mountimage processing software
• Steep learning curve
• Time consuming- one or two objects per night
  analysis of data in real-time is difficult
• Bright objects (mag 9-10 saturate pixels on CCD
  chip)

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Visual observing

• Pros
• Relatively easy
• Can be made with inexpensive equipment eg
  binoculars
• Experienced observers can observe 50-100 stars
  per night
• Data analysis quick and simple
• Good for brighter variables as bright stars
  saturate pixels on CCD chips
• Cons
• Accuracy only 0.1 magnitude for experienced
  observers
• No permanent record of observation

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Conclusion Visual or CCD?

• Visual observations still have a very useful role
  to play
• Visual and CCD observers can complement each
  other
• Visual observers can monitor brighter stars and
  check for outbursts
• CCD observers can monitor stars in quiesence and
  do time-series photometry to build detailed
  lightcurves