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Discover the insights from a study on the instrumental features of CCD cameras by Dhruv Paranjpye in Pune, India, under the guidance of Prof. Bob Buccheim and Prof. Paula Turner. The research delves into the linearity, uniformity, dark current, color, and magnitude transforms of CCD cameras. The study involved using a Light Box and data analysis techniques to understand CCD behavior, sensitivity, and response to different stimuli. The findings show the linearity limit, uniform illumination, and the Arrhenius Law's application to dark current. The study also covers color and magnitude conversions using transformation coefficients to standardize results. Acknowledgments to data sources, such as AAVSO Photometric All-Sky Survey, Minor Planet Center, and references from papers and books like "The Sky is your Laboratory - Buccheim." Software tools like MaxIM DL and The Sky Sky Map Pro 8 were employed in the research.
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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 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.
Procedure A Light Box was mounted on top of the optical tube.
Surprising Result! We measure the sensitivity of different regions wrt the centre. Flat Field Star Field
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.
Color and Magnitude Transforms • Each filter we use, has a different response than the other even if they’re manufactured by the same company.
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.
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
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
m= -0.0828 Color Transform coefficient = 0.923
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
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