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:
- Finding best image as template based on multiple image quality parameters.
- Finding co-ordinate transformation relations between template/reference image and other frames for cross-identifying stars or aligning images.
- 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.
- Automatically determine parameters or other image information - like readnoise, gain, filter, Julian date - using a telescope database.
- Doing aperture or PSF photometry.
- Multi-threaded photometry is supported, where multiple images are processed parallelly, reducing execution time by several folds.
- Then perform relative calibration of image frames for differential photometry.
- Optionally Astrometry can be also done if needed.
- Standard calibration can be done using SDSS, PanSTARRS, 2MASS or APASS catalog as needed
- Interactive mode - functions are provided for Displaying images with target and field stars labeled along with aperture and sky annuls drawn.
- 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.
- 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.