GSC 36561328

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GSC 3656-1328

• A Nearby
• Microlens
• Pro-Am Collaboration

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GSC 3656-1328

• Discovered 10/31/2006 by Akihiko Tago
• An 11th Magnitude Star Brightens to 7th Magnitude

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GSC 3656-1328

• Discovery Announced Through CBETs
• AAVSO Alert Issued - Var Cas 06
• Two CBA Observers Immediately Begin Lightcurves

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Professionals Join In

• Swift X-Ray Satellite - No X-Rays
• RXTE All-Sky Monitor - No X-Rays
• Ulisse Munari, Padova -Spectrum of Ordinary A
  Star
• Sergie Antipin, Sternberg - Plate Search,
  Constant Magnitude

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Professional Observations

• Spectra, MDM 2.4-m On Kitt Peak
• Lightcurve, Peters Automated Infrared Imaging
  Telescope, 1.3-m, Mt. Hopkins
• Swift Satellite, UV-Band Observations

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Interpretation Begins

• British Astronomer Reviews Data - Microlens?
• Maciej Mikolajewski, Nicholas Copernicus
  University, Suggests Microlens Explanation

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Hunting for Microlenses

• OGLE in Chile, MicroFUN in New Zealand
• Best Background LMC and Milky Way Bulge
• Odds of Sighting Increase With SQUARE of the
  Distance to the Source Star
• GSC 3656-1328, 1 KPsc Distant, Is Low Probability

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But Is It a Microlens?

• Must Fit Mathematical Model
• Must Have Constant Color/ Spectrum
• Must Be Symmetrical -Earlier Observations Needed
• British Amateurs and ASAS to the Rescue

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The Lens

• Mass 1/6 Solar Mass
• Brown Dwarf or Main Sequence, V20
• Distance 130 parsec
• Motion 150 mas/yr
• May Be Resolvable In A Few Years
• (Gaudi et al, 2007)

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Lightcurve Opportunities

• Asteroids
• Variable Stars
• Targets of Opportunity

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GSC 3656-1328

• A Nearby
• Microlens
• Pro-Am Collaboration