Implementation and Analysis of an OpenMP-Based Parallel Differential-Photometry Algorithm

Differential-photometry is a technique for obtaining precise relative photometry of variable sources in crowded stellar fields. Its basic principle is to derive temporal photometric variations of objects by subtracting images of the same region recorded at different moments after convolved by a kernel. Traditional image-subtraction algorithms for differential photometry use serial computing and are low in efficiency. This paper discusses the principle of differential photometry and gives a reliable parallel-computing algorithm of differential photometry based on the OpenMP technology and the open-source software ISIS. The algorithm significantly increases the efficiency.