
psphot description article (outline)

- background

  - discuss dophot, sextractor, daophot
  - other photometry solutions?

- process

  - image preparation

    - load image
    - measure sky level & noise
    - construct noise image
    - construct mask image

  - PSF determination 

    - initial object detection (find peaks)
    - measure object moments & basic properties
    - classify on basis of moments
    - select likely PSF stars
    - test PSF model functions
    - select best PSF model function
    - aperture correction  
    
    - aperture photometry vs psf photometry

      - aperture is always the reference
      - how do we choose an appropriate aperture
      - how do we measure the aperture correction?
      - predicting / correcting for aperture loss?

  - apply PSF to sources

    - use dsigma to select PSF-like objects
    - fit and subtract PSF-like objects

  - fit non-stellar objects

    - galaxy models
    - asteroid models
    - low S/N limits

- user's guide

  - configuration parameters
  - input images / output files
  - command-line arguments

- demonstration tests

  - simulated data
    - astrometric accuracy 
      - as a function of S/N
      - as a function of crowding
      - as a function of fringe residual amplitude & scale
      - as a function of PSF model quality
      - as a function of seeing
    - photometric accuracy 
      - as a function of S/N
      - as a function of crowding
      - as a function of fringe residual amplitude & scale
      - as a function of seeing
      - as a function of PSF model quality
  - real data
    - quality of galaxy models
    - accuracy of PSF models (megacam, cfh12k, suprime, skyprobe?)

