DiffPhot Package

Diffphot is a Python package for pipelining differential photometry of time-series data. The package can be used as a fully automated data reduction pipeline or can be used as a interactive data reduction tool in a iPython or Notebook interface.

Diffphot can do following tasks in automated or interactive modes:

  1. Finding best image as template based on multiple image quality parameters.
  2. Finding co-ordinate transformation relations between template/reference image and other frames for cross-identifying stars or aligning images.
  3. An advanced 'deepfind' algorithm is available where co-ordinate transformation be two images can be found even if images don't overlap. In such cases, the program will try to find another (best) image(s) from the data-set which can connect the two images by partial overlapping.
  4. Automatically determine parameters or other image information - like readnoise, gain, filter, Julian date - using a telescope database.
  5. Doing aperture or PSF photometry.
  6. Multi-threaded photometry is supported, where multiple images are processed parallelly, reducing execution time by several folds.
  7. Then perform relative calibration of image frames for differential photometry.
  8. Optionally Astrometry can be also done if needed.
  9. Standard calibration can be done using SDSS, PanSTARRS, 2MASS or APASS catalog as needed
  10. Interactive mode - functions are provided for Displaying images with target and field stars labeled along with aperture and sky annuls drawn.
  11. Interactive mode - functions for plotting light curves and showing data tables at various stages of reductions. Photometric uncertainties, relative calibration uncertainties and standard calibration uncertainties are also listed individually.
  12. In interactive mode, problematic images can be investigated individually, parameters can be tweak as needed and then photometry steps can be re-run for the particular frame.

Diffphot has lot of advanced functionality and is highly configureable. A detailed documentation of this package is currently not available but will be done in future.