Spatial Analysis

subsection 6.1Summary of Tasks in this Section79 subsection 6.2Regions and Source Parameters79 subsection 6.3Radial Profiles and Projections87 subsection 6.4Smoothing and Contouring92 subsection 6.5Calibration95 subsection 6.6Point Response Functions103 subsection 6.7Image Manipulation103 subsection 6.8Source Subtraction106 subsection 6.9Detect109

This chapter deals with analyzing source positions and spatial structure and with image calibration. Depending on the specific scientific task, the user may wish to block or section the input data file for convenience (See also Display). See Table 6.1 for the dimensions of ROSAT and Einstein images:

• Summary of Tasks in this Section
• Regions and Source Parameters
  • *plcreate* --- Defining a Region
  • *pllist* -- Look at the region
  • *isoreg* -- A region defined by an isointensity contour
  • *imcnts* -- Find background subtracted counts for a point source
  • *imcnts* -- Find counts in an extended region, after removing an embedded point source
  • *imexamine* -- General analysis of image containing many sources
    • Photometry
    • Contour Plot
    • Other Useful Functions
  • *tprint* -- Reading a Table File Created by imcnts
  • *imcnts* -- Use of the Sky Coordinate System
• Radial Profiles and Projections
  • *imcnts* -- Radial Profile of an extended source at the field center
  • *tabplot* -- Displaying a Radial Profile
  • *imcnts* -- Azimuthal profile of an extended source
  • *imcnts* -- Radial Profile in a Quadrant
  • *improj* -- Make a one-dimensional projection of data within a rectangular band traversing an image
• Smoothing and Contouring
  • *imsmooth* -- Smooth an image
  • Calculation of errors in smoothed arrays
  • *imcontour* -- Iso-intensity contour map
• Calibration
  • Vignetting correction
    • *makevig, vigdata* -- Apply Vignetting Correction to an image
  • Exposure Map
  • Background Corrections
    • *imcalc* -- Obtain a background subtracted image for ROSAT PSPC Data
    • Radial profile of an extended source for Einstein IPC data.
  • *errcreate* -- Use of error arrays
    • Determine a background subtracted radial profile
  • To Resample Calibration Images
• Point Response Functions
  • On-Axis Point Response Functions (PRF)
  • ROSAT and EINSTEIN Calibration Fields
• Image Manipulation
  • *imcopy* -- Extract a small image file from a larger image
  • *imcopy* -- Compress an image and extract a small region
  • *imcalc* -- Image Arithmetic
  • *imlintran, magnify* -- Image Scale, Orientation, and Translation
• Source Subtraction
  • *immodel* -- subtracting a King model
  • *rosprf* -- Using the analytical expressions for the point response function
• Detect