The Legacy Surveys, a combination of three ground-based imaging surveys, have mapped 16,000 deg2 in three optical bands (g, r, and z) to a depth 1--2~mag deeper than the Sloan Digital Sky Survey (SDSS). Our work addresses one of the major challenges of wide-field imaging surveys conducted at ground-based observatories: the varying depth that results from varying observing conditions at Earth-bound sites. To mitigate these effects, two of the Legacy Surveys (the Dark Energy Camera Legacy Survey, or DECaLS; and the Mayall z-band Legacy Survey, or MzLS) employed a unique strategy to dynamically adjust the exposure times as rapidly as possible in response to the changing observing conditions. We present the tiling and observing strategies used by these surveys. We demonstrate that the tiling and dynamic observing strategies jointly result in a more uniform-depth survey that has higher efficiency for a given total observing time compared with the traditional approach of using fixed exposure times.
@article{arxiv.2002.05828,
title = {Observing Strategy for the Legacy Surveys},
author = {Kaylan J. Burleigh and Martin Landriau and Arjun Dey and Dustin Lang and David J. Schlegel and Peter E. Nugent and Robert Blum and Joseph R. Findlay and Douglas P. Finkbeiner and David Herrera and Klaus Honscheid and Stéphanie Juneau and Ian McGreer and Aaron M. Meisner and John Moustakas and Adam D. Myers and Anna Patej and Edward F. Schlafly and Francisco Valdes and Alistair R. Walker and Benjamin A. Weaver and Christophe Yèche},
journal= {arXiv preprint arXiv:2002.05828},
year = {2020}
}
Comments
v1: 14 pages, 3 tables and 5 figures; v2: 15 pages, 3 tables and 6 figures. Changes in response to referee comments; matches published version