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29.2 General Outline for Handling FOS Data

A brief outline of the steps suggested for an FOS project follows:

  1. Select data for retrieval from HST Archive.
  2. Examine the data in StarView. (FOS paper products could also be used for an initial quick look).
  3. Recalibrate all data to benefit from the latest calibration updates and calfos enhancements, as described in Chapter 31 (which includes a calibration checklist).
  4. Run FOS paper products to evaluate data quality and anomalies. (Refer to the exposure logsheet or RPS2 (RPSS) Phase II specifications if desired).
  5. Analyze your data. You must have some basic knowledge of the FOS and its capabilities in order to refine your archive data search. The remaining sections of this chapter provide an overview of the FOS and, for certain very detailed information, direct you to other sources of information such as the FOS Instrument Handbook.

    On the basis of your understanding of FOS modes and capabilities you will search the Archive and retrieve observations that may meet your objectives. Using StarView to browse and retrieve data from the Archive is described in Chapter 29.

    StarView provides an easy way to quickly assess prospective data, reflecting the original post-observation calibration. Large sets or bulk retrievals can be assessed efficiently at your site with the FOS paper products.

    Next, you must recalibrate the observations to obtain the benefit of the FOS closeout calibration and algorithm updates. The accuracies of any FOS data stored in the HST Archive will be improved by recalibration. Chapter 31 describes the recalibration process.

    After recalibrating the data, you will want to assess the results and understand the limitations of the calibration as they apply to your data. The FOS paper products, described in Chapter 30, are useful for this purpose. After you evaluate your overall data quality with the paper products you should refer to the description of error sources and accuracy limitations found in Chapter 32. Occasionally, the details of the original observation strategy can be useful in understanding calibration limits for particular types of data. Referring to the exposure logsheet and the data quality assessment material in Chapter 30 may help.

    Analyze your data. Although the major focus of this handbook is on understanding FOS calibrations and their accuracies as applied to your data, a few routines that may be useful for specific types of analysis of FOS data are discussed in Chapter 33.

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