NAME

playpen -- Prototype STSDAS tasks

INTRODUCTION

Tasks or packages that are being developed are often placed in the `playpen' package. This provides often very useful functionality to users early in the development phase of a package. While `playpen' might rightly be considered a testbed for new utilities, the tasks themselves have undergone the same testing and validation as other STSDAS tasks. Users should simply be aware that the functionality, the user interface, the parameters, and even the task names themselves may change with little or no warning. As tasks or packages are more fully developed, they may be moved elsewhere within STSDAS -- e.g., to the `analysis' package -- but this will usually occur with major releases, rather than with minor, "patch" releases. A brief summary of the tasks is given in the table below; details may be found in the following sections.

                     Table 1. PLAYPEN Tasks
 +---------------------------------------------------------------+
 | Task         | Description                                    |
 +---------------------------------------------------------------+
 | edge         | 2-D image edge massaging                       |
 | fill         | Baade-Lucy background filling algorithm        |
 | hstpos       | Show the position of HST on a world map        |
 | hsubtract    | Baade-Lucy background subtraction algorithm    |
 | immean       | Compute image mean & save as a task parameter  |
 | jimage       | Create a jitter image from U2,U3 coordinates   |
 | lgrlist      | Expand a list of image names & group numbers   |
 | saolpr       | Print and image from the display               |
 +---------------------------------------------------------------+

GENERAL DESCRIPTION

The `hsubtract' and `fill' tasks implement the Baade-Lucy algorithms for dealing with sky background in direct images. This method is designed to take care of the spatial high-frequency component in the background. It fills "pits" (pixels below the average background) by local flux reshuffling. The `hsubtract' task subtracts a reference background, either from a reference image or a computed background. These tasks, along with the `edge' task for modifying image edges by windowing or overlapped edge extension, are useful for contitioning images prior to using the image restoration tasks.

The `lgrlist' task is an enhancement of the `stplot.grlist' task. It expands a list of image names, including a range of group numbers, into an explicit list of individual image names with an explicit section and group number. This input list of images can include wildcards, @-lists, etc.

Two HST-specific utilities are also included in the `playpen' package. The `jimage' task uses a list of U2-U3 pointing coordinates and creates an image that reflect the "jitter" information. The `hstpos' task plots the position of HST at specified times on a Mollweide projection of the world. The task uses information contained in the headers of uncalibrated, GEIS- format HST data, and is most useful for determining whether a given observation was likely to be affected by terminator crossings, or by the South Atlantic Anomaly. The `geo2mag' task for converting geocentric coordinates to and from geomagnetic coordinates, while not HST specific, is also useful for gaining insight about the quality of HST data.

SEE ALSO