Optimization of exposure time division for wide field observations

Abstract

The optical observations of wide fields of view encounter the problem of selection of best exposure time. As there are usually plenty of objects observed simultaneously, the quality of photometry of the brightest ones is always better than of the dimmer ones. Frequently all of them are equally interesting for the astronomers and thus it is desired to have all of them measured with the highest possible accuracy. In this paper we present a novel optimization algorithm dedicated for the division of exposure time into sub-exposures, which allows to perform photometry with more balanced noise budget. Thanks to the proposed technique, the photometric precision of dimmer objects is increased at the expense of the measurement fidelity of the brightest ones. We tested the method on real observations using two telescope setups demonstrating its usefulness and good agreement with the theoretical expectations. The main application of our approach is a wide range of sky surveys, including the ones performed by the space telescopes. The method can be applied for planning virtually any photometric observations, in which the objects of interest show a wide range of magnitudes.Comment: 18 pages, 5 figure