APPHi: An automated photometry pipeline for high cadence, large volume data

Abstract We present the software package APPHi ( A utomated P hotometry P ipeline for Hi gh Cadence, Large Volume Data), developed to carry out in a computationally-efficient manner, the aperture and differential photometry of the large volume of data to be produced by the TAOS-II project. However, it can also be used to process other astronomical, wide field image data. The main features of the APPHi package are: its computational speed, the capacity to work with large volume data and to handle both FITS and HDF5 image formats. Due to the large number of stars (in excess of 10 4 ) that the software has to handle in a great number of frames (more than 10 5 for a typical TAOS-II visit), it is optimized to automatically find the best value for parameters to carry out the photometry, such as: mask size for aperture, size of the window for extraction of a single star and the number of counts for the threshold for faint star detection. Using images with similar features to those that will be collected in the TAOS-II project, we carry out a comparative performance study with the widely used software IRAF, and find that APPHi can obtain light curves of comparable quality, in terms of the Signal to Noise Ratio over the light curve ( S N R L C ), up to 300 times faster. In addition to its efficiency, the tests carried out prove that APPHi, although intended to work with TAOS-II data, can also be used to analyze other sets of astronomical images, being a robust and versatile tool to perform aperture and differential photometry of point sources.