Problems with twilight/supersky flat-field for wide-field robotic telescopes and the solution
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 s...
| Main Authors: | , , , , , |
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| Format: | Text |
| Language: | unknown |
| Published: |
arXiv
2014
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| Subjects: | |
| Online Access: | https://dx.doi.org/10.48550/arxiv.1407.8283 https://arxiv.org/abs/1407.8283 |
| Summary: | 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. : 7 pages, 5 figures, Proc. SPIE 9149 (2014) |
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