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Photometric Data Collection At The Burke Gaffney Observatory

Photometric Data Collection At The Burke Gaffney Observatory. By Jayme Derrah. Overview. Photometry At The BGO The Photometer Collecting Data Extinction Polaris Results Problems Encountered. Photometry At The BGO. No one has done this at the BGO for years

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Photometric Data Collection At The Burke Gaffney Observatory

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  1. Photometric Data Collection At The Burke Gaffney Observatory By Jayme Derrah

  2. Overview • Photometry At The BGO • The Photometer • Collecting Data • Extinction • Polaris • Results • Problems Encountered

  3. Photometry At The BGO • No one has done this at the BGO for years • Collect data in hopes of finding extinction coefficients for Halifax skies. • No other observations in Halifax to compare with • Collect data on several Cepheid Variable stars, including Polaris

  4. Optec SSP-3 Photometer Works like a 1 pixel CCD Measures apparent brightness of the object in question The Photometer

  5. Collecting Data • Take readings in the blue, visual and ultraviolet ends of the spectrum • Most readings on the sky are dominated by noise in the uncooled photometer • Need to collect data on standard stars at different air masses • For variable stars, a nearby reference star is needed

  6. Data • Use the apparent brightness readings to determine the apparent magnitude of the object using the equation: m1-m2= 2.5*log(b1/b2)

  7. Extinction • Produced by haze, clouds, fog, which cause changes in sky transparency • Greater extinction at larger distances from zenith • The greater the air mass, the more light that is absorbed . • With accurate extinction coefficients, can standardize data collected on stars, such as Polaris

  8. Extinction (continued) • To determine accurate extinction coefficients, need readings on many different standard stars observed at a variety of air masses k'y = 0.213 (0.13-0.16 at 7000 ft) k"y = -0.025 (0.00 at 7000 ft) k'by = 0.154 (0.10-0.13 at 7000 ft) k"by = -0.033 (same at 7000 ft) k'ub = 0.281 (0.21-0.25 at 7000 ft)

  9. Polaris • Polaris is the closest and brightest Cepheid Variable star to us • Cepheids are variable stars whose luminosities are proportional to their periods • Polaris has a period of about four days • Its period is slowly increasing, and it may soon stop pulsating since its amplitude is decreasing • Not many observations done on it for years • The air mass around Polaris stays relatively constant, so it is good to observe at the BGO

  10. Results • Light curve from last summer:

  11. Problems Encountered • Transparency changes throughout the night • Thin cirrus clouds often difficult to detect • Tightening the clamps on the telescope • Aligning the telescope • Finding Polaris and the stars in its field

  12. ThankYou • Special thanks to Dr. David Turner

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