1 Introduction

The CUPID package provides a set of tools for identifying and analysing clumps of emission within 1, 2 or 3D data arrays. Specifically, it currently provides the following facilities:

• background removal (uses spatial filtering to remove features with scale sizes greater than a given value).
• identification of clumps of emission using a variety of different algorithms (e.g. FellWalker, GaussClumps, ClumpFind, etc).
• creation of catalogues of clump parameters
• creation of cut-out images containing the emission from individual clumps.

CUPID processes data in NDF format. This is the standard data format used by most Starlink software, and is described fully in SUN/33. However, other astronomical data formats may also be processed using transparent on-the-fly data conversion facilities provided by the NDF subroutine library, and the CONVERT package. The use of these facilities in SUN/55.

All CUPID applications use standard Starlink subroutine libraries for accessing parameters, producing graphics, reporting errors, etc. They therefore look and feel very similar to applications in other Starlink packages such as KAPPA and CCDPACK. The following sections in SUN/95 (the KAPPA manual) should therefore be consulted for general information about these issues:

• “Bad pixel values”
• “Parameters”
• “Graphics Devices and Files”
• “Plotting Styles and Attributes”
• “Data Structures”
• “NDF Sections”
• “NDF History”
• “The Graphics Database”
• “Using World Co-ordinate Systems”

1.1 Available Commands

Currently, the following commands are available within CUPID:

CLUMPINFO

- Obtain information about one or more previously identified clumps;

CUPIDHELP

- gives on-line help for all CUPID commands;

EXTRACTCLUMPS

- calculates parameters for the clumps within a 1, 2 or 3D data array, given a mask array that identifies the pixels within each clump;

FINDBACK

- applies spatial filtering to a 1, 2 or 3D array in order to remove features smaller than a specified size and thus produce an estimate of the background within the NDF;

FINDCLUMPS

- finds clumps within a 1, 2 or 3D array and produces a mask identifying the pixels included in each clump. Also produces a catalogue of clump parameters. Various clump identification algorithms are supported such as ClumpFind, GaussClumps, etc.

MAKECLUMPS

- creates a 1, 2 or 3D array containing a collection of random Gaussian clumps, with added noise.

OUTLINECLUMP

- draw an outline on a previously displayed image around a 2-dimensional clump.