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Instrumental Characteristics of CCD camera

Instrumental Characteristics of CCD camera. “To work for 5 days isn’t the challenge; to present all that in 10 mins is!”. Dhruv Paranjpye Pune, India. Guides: Prof. Bob Buccheim Prof. Paula Turner. Linearity.

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Instrumental Characteristics of CCD camera

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  1. Instrumental Characteristics of CCD camera “To work for 5 days isn’t the challenge; to present all that in 10 mins is!” Dhruv Paranjpye Pune, India. Guides: Prof. Bob Buccheim Prof. Paula Turner

  2. Linearity A CCD is an array of pixels on which photons are collected and counted as ADUs (Analog to Digital Units). Goal: Find out how does number of photons collected varies with exposure.

  3. Procedure A Light Box was mounted on top of the optical tube.

  4. The CCD saturates at 64,600 ADUs

  5. The CCD response is linear up to ~50,000 ADUs

  6. Uniformity

  7. Surprising Result! We measure the sensitivity of different regions wrt the centre. Flat Field Star Field

  8. Dark Current against Temperature De = Dark Current Do = Constant Delta E = Activation energy T = Temperature in Kelvin K = Boltzman constant According to the equation the logarithm (natural) of dark current vs inverse of temperature should be a linear graph. Source: Paper by Widenhron, Blouke, Weber, Rest, Bodegom, University of Washington, Seattle.

  9. Color and Magnitude Transforms • Each filter we use, has a different response than the other even if they’re manufactured by the same company.

  10. Image in B filter 1 Image in V filter 2 There is a difference in the magnitudes we measure using 2 different filters. So we transform them into a standard result by using transformation coefficients! This will make all our results standard. 1 & 2: Images of Asteroid 107 Camilla by Prof. Bob Buccheim and Garrett Minta.

  11. Data for Instrumental Magnitude Slope of V-v against B-V gives the transformation coefficient for magnitude1 Standard data obtained from AAVSO Photometric All Sky Survey (APASS) and instrumental data from a star field in Lyra. • The sky is your laboratory – Robert K Buccheim; pg 169 - 170

  12. Data for color magnitude If m= slope of graph of [B-V]-[b-v] vs B-V then the color transform coefficient is 1/(1-m) 1 Standard data obtained from AAVSO Photometric All Sky Survey (APASS) and instrumental data from a star field in Libra. 1. The sky is your laboratory – Robert K Buccheim; pg 169 - 170

  13. m= -0.0828 Color Transform coefficient = 0.923

  14. Conclusion The CCD is very linear at the limit of ~52000 ADUs. The light box is uniformly illuminating the CCD with a maximum error of about 1% Dark current of CCD follows the Arrhenius Law. Magnitude Coefficient = 0.0556 Color Coefficient = 0.923

  15. Acknowledgements • Source of data: AAVSO Photometric All Sky Survey (APASS). www.aavso.org • Minor Planet Center www.minorplanetcenter.net • Papers: Paper by Widenhron, Blouke, Weber, Rest, Bodegom, University of Washington, Seattle. • Books: The Sky is your Laboratory – Buccheim • Software: MaxIM DL The Sky Sky Map Pro 8

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