The MultiDrizzle Handbook
1.1 How to Use The MultiDrizzle Handbook
The MultiDrizzle Handbook is designed to help users learn about combining dithered observations. The information in this handbook has been drawn from the various individual HST instrument handbooks, as well as a considerable number of other separate documents available on the STScI Web site:
In Chapter 8, a bibliography of the relevant material is presented at the end of this handbook. The information in many of these older documents is out-of-date and has been updated as necessary when included in this handbook. They are referenced primarily for the sake of bibliographic completeness, and if they are consulted this caveat should be borne in mind.
Dithers are observations where the telescope is offset between exposures. The most common way of combining dithered HST images is to use the "Drizzle" algorithm (Fruchter & Hook 2002). This is predominantly done through the "MultiDrizzle" program (Koekemoer et at. 2002), which also performs many of the steps necessary between acquiring your data from the HST archive and combining it using the drizzle algorithm.
Users of HST range from the novice to the experienced black belt drizzler, So different users may want to use these pages in different ways. These are some suggestions for how to proceed:
- If you do not have a good grasp of the ideas behind dithering observations or drizzling data, we suggest you start with Chapter 1 "Dithering Basics" and Chapter 3 "How the Drizzle Algorithm Works". You may then wish to skip right to the Chapter 6 "Real-World Examples" and work backwards to the more detailed descriptions of parts of the MultiDrizzle code as needed.
- If you have experience with dithered data, and have used Drizzle or MultiDrizzle before, but are not sure you are up-to-date with the latest software, you may wish to go directly to the example pages to see how to use the latest version of MultiDrizzle. You can then use other chapters as required.
- If you have used MultiDrizzle extensively in the past, or have your own code for combining dithered images and are interested in the details, you may find most of the information you need in the sections detailing the astrometric header information and the MultiDrizzle parameters.
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