6 August 2014 Problems with twilight/supersky flat-field for wide-field robotic telescopes and the solution
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Twilight/night sky images are often used for flat-fielding CCD images, but the brightness gradient in twilight/ night sky causes problems of accurate flat-field correction in astronomical images for wide-field telescopes. Using data from the Antarctic Survey Telescope (AST3), we found that when the sky brightness gradient is minimum and stable, there is still a gradient of 1% across AST3’s field-of-view of 4.3 square degrees. We tested various approaches to remove the varying gradients in individual flat-field images. Our final optimal method can reduce the spatially dependent errors caused by the gradient to the negligible level. We also suggest a guideline of flat-fielding using twilight/night sky images for wide-field robotic autonomous telescopes.
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Peng Wei, Peng Wei, Zhaohui Shang, Zhaohui Shang, Bin Ma, Bin Ma, Cheng Zhao, Cheng Zhao, Yi Hu, Yi Hu, Qiang Liu, Qiang Liu, } "Problems with twilight/supersky flat-field for wide-field robotic telescopes and the solution", Proc. SPIE 9149, Observatory Operations: Strategies, Processes, and Systems V, 91492H (6 August 2014); doi: 10.1117/12.2055459; https://doi.org/10.1117/12.2055459


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