The VVV-SkZ Pipeline: How to Get Automatic PSF-Fitting Photometry from the VVV Survey

We present the VVV-SkZ_pipeline, a DAOPHOT-based pipeline created to perform PSF-fitting photometry of the “VISTA Variables in the Vía Láctea” (VVV) ESO Public Survey data. The pipeline avoids repetitive interaction by the user, but still retains all the benefits, power, and accuracy of the DAOPHOT suite. The pipeline provides an astrometrized photometric catalog in the regime where other techniques fail, for example, producing reliable results up to 2 magnitudes brighter than the saturation limit. It also produces deeper and more accurate photometry. These achievements allow the VVV-SkZ_pipeline to produce data well anchored to the selected standard photometric system and allows the study of important stellar phenomena (i.e., tip of the red giant branch stars, red giant branches, horizontal branch morphology, RR Lyrae stars), that may be beyond the reach using other methods of photometric reduction.