Digital stacking of photographic plates with SuperCOSMOS
Abstract
Photographic Schmidt plates are among the most effective tools in wide-field astronomy. One of the principal difficulties of photographic plates when compared to modern detectors is lack of image depth. We present a technique for stacking plates digitized using the SuperCOSMOS microdensitometer, aimed at maximizing the signal-to-noise ratio in faint images. The efficacy of several image combination algorithms is tested by stacking plate frames in the presence of spurious images. We find that an `average sigma clipping' type pixel rejection in conjunction with our weighting scheme is most effective in delivering a clean, high signal-to-noise ratio stack. The gain in limiting magnitude obtained from stacking is found to be consistent with that expected: DeltaM~1.5 for a stack of 16 good-quality plates.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- July 1998
- DOI:
- 10.1046/j.1365-8711.1998.01558.x
- Bibcode:
- 1998MNRAS.297..839K
- Keywords:
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- INSTRUMENTATION: MISCELLANEOUS;
- METHODS: DATA ANALYSIS;
- TECHNIQUES: IMAGE PROCESSING