The Optical Gravitational Lensing Experiment. Difference Image Analysis of LMC and SMC data. The Method

TL;DR

This paper details the Difference Image Analysis algorithms and software applied to four years of OGLE-II data of the Magellanic Clouds, focusing on photometric calibration, error analysis, and variable star detection.

Contribution

It introduces the DIA method and software tailored for OGLE-II data, enabling efficient analysis of variable stars in the Magellanic Clouds.

Findings

Analysis of photometric errors in LMC_SC2

Detection of approximately 70,000 variable stars

Development of DIA algorithms for large-scale surveys

Abstract

We describe the Difference Image Analysis (DIA) algorithms and software used to analyze four years (1997-2000) of OGLE-II photometric monitoring of the Magellanic Clouds, the calibration, the photometric error analysis, and the search for variable stars. A preliminary analysis of photometric errors is based on the field LMC_SC2. A full catalog of about 70,000 variable stars will be presented in a separate publication.