Throughout my time as an observational astronomer, I have obtained and reduced many hundreds of gigabytes of data. Much of this data comes in the form of time-series photometry, meaning hudreds of consecutive images taken in intervals of a few seconds over the course of minutes to hours for single stars. Ultimately these images need to be converted into light curves indicating the brightness of the star versus time. To get from raw images to light curves, the following steps are performed:
- Image Calibrations (Dark, Flat, and Bias corrections)
- Aperture or PSF Photometry
- Light Curve Extraction
phot2lc was born from the desire to have a more efficient tool for the light curve extraction step, especially in the event that light curves from multiple aperture sizes need to be analyzed to determine the which aperture optimizes the signal-to-noise ratio of the light curve.
phot2lc is a pure-Python interactive program for light curve extraction inspired largely by WQED (Thompson & Mullally 2009, 2013). While not nearly as extensive in its scope as WQED, phot2lc has several key features which make it a much more efficient and user-friendly tool for light curve extraction. The first such feature is its ease of installation. phot2lc is a Python package and can be installed with:
pip install phot2lc
Detailed documentation for phot2lc can be found at phot2lc.readthedocs.io
List of Features
- Standard Light Curve Manipulation Tools:
- Delete/Add single points
- Delete points inside and outside a drawn box
- Divide by a polynomial of chosen order
- Delete outliers with a sigma clipping routine
- Comparison star selection
- Analyzes photometry for all apertures sizes at once
- Automated determination of optimal aperture size
- Automated determination of optimal comparison star combination
- Barycentric time corrections with Astropy accounting for:
- Object RA and Dec Coordinates
- Observatory Location
- Leap Seconds
- Additional tools for post-processing:
- weldlc for combining light curves
- quicklook for quick analysis of light curves and their periodograms
- Automatically loads previous changes made to a light curve (i.e. same deleted points, polynomial, and comparison stars) when phot2lc is re-run for an object.