PSF photometry for BRITE* nano-satellite mission

摘要

The BRIght Target Explorer (BRITE) is a space mission consisting of five nano-satellites aimed at the observations of microvariability of the brightest stars. Since the end of 2013, this ongoing mission has provided photometric data for nearly 500 bright stars in the sky. Taking the advantage of currently employed chopping mode of observing, a new PSF-fitting based photometric pipeline was developed for the BRJTE data. The motivation for a new procedure was the expected increase of photometric precision for the dimmest objects. The proposed new method uses the principal component analysis (PCA) decomposition of stellar profile into a set of eigen-PSFs, which allows for adaptive fitting to PSFs modulated either by the blurring or by the variations of the intra-pixel sensitivity. The first results of the new pipeline confirm its good performance: for faint stars the PSF photometry results in a smaller scatter than the current photometry, while for the brightest stars the results from both pipelines are comparable. The superiority of a novel technique is evident for the most degraded sensors which makes the proposed pipeline a promising solution for the next years of the mission.