Book contents
- Frontmatter
- Contents
- Preface and Acknowledgements
- dedication
- Section I Terminator Observation and Interpretation
- Section II Atlas
- 3 Arrangement of the Atlas
- 3 Making the Mosaics
- 4 Near Full
- Appendix: Lunar Physical Ephemeris, 2000-2010
- Bibliography
- Mosaic Feature Index
- Subject Index
- Individual Features Index
3 - Making the Mosaics
from Section II - Atlas
Published online by Cambridge University Press: 05 February 2015
- Frontmatter
- Contents
- Preface and Acknowledgements
- dedication
- Section I Terminator Observation and Interpretation
- Section II Atlas
- 3 Arrangement of the Atlas
- 3 Making the Mosaics
- 4 Near Full
- Appendix: Lunar Physical Ephemeris, 2000-2010
- Bibliography
- Mosaic Feature Index
- Subject Index
- Individual Features Index
Summary
Chapter 1 has described the general process of obtaining individual CCD images. However, one image does not make a mosaic, so it is pertinent here to describe how images intended for mosaics are acquired, processed, and then assembled.
A series of images that are to be mosaiced must be as uniform as possible; this means no changes in the exposure time, camera orientation, optical system, or filter (or lack of filter) can occur while the series is being exposed. Any cloudiness, even thin clouds, is usually fatal because the Moon's brightness will change between images. Indeed, if the Moon is at a low altitude, the series must be completed quickly because the transparency even of the clear atmosphere will change rapidly. Another reason not to dawdle excessively is that the colongitude changes by a tenth of a degree every 11-12 minutes.
The writer's procedure is to begin each series at the northern limb, then to expose frames successively southward along the terminator until he reaches the southern limb. The exposure time is adjusted by trial and error so that features 8°-10° from the terminator are on the point of “saturation” (overexposure), to ensure continuity with the previous and subsequent mosaics. Naturally, it is important to be sure that each frame overlaps its neighbors; preferably by 10-20 percent.
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- Atlas of the Lunar Terminator , pp. 57 - 151Publisher: Cambridge University PressPrint publication year: 2000
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