PSF or DIA data from OGLE II?

OGLE (Optical Gravitational Lensing Experiment) has a large database of photometry data available to the public. OGLE II data (second phase) are available with option to select the photometry method used, ie. PSF and DIA photometry.

PSF, a modified DOPHOT photometry process, was used during the first phase of OGLE, while the DIA process (Difference Image Analysis) was developed at the same time with phase two (OGLE II). As stated in Szymanski 2005 (AcA, 55, 43 or arXiv)  the DIA method was successful enough and yielded better results than the previous PSF method, which prompted them to recalculate all the OGLE II data and use it at the pipeline of OGLE III. In order to get though the absolute values, standard PSF photometry is applied to the DIA reference images.

So, it seems that DIA data may be the best ones to use (depending on the project and the objects of course).

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