The Atacama Cosmology Telescope: Data Characterization and Map Making
Abstract
We present a description of the data reduction and mapmaking pipeline used for the 2008 observing season of the Atacama Cosmology Telescope (ACT). The data presented here at 148 GHz represent 12% of the 90 TB collected by ACT from 2007 to 2010. In 2008 we observed for 136 days, producing a total of 1423 hours of data (11 TB for the 148 GHz band only), with a daily average of 10.5 hours of observation. From these, 1085 hours were devoted to a 850 deg^2 stripe (11.2 hours by 9.1 deg) centered on a declination of -52.7 deg, while 175 hours were devoted to a 280 deg^2 stripe (4.5 hours by 4.8 deg) centered at the celestial equator. We discuss sources of statistical and systematic noise, calibration, telescope pointing, and data selection. Out of 1260 survey hours and 1024 detectors per array, 816 hours and 593 effective detectors remain after data selection for this frequency band, yielding a 38% survey efficiency. The total sensitivity in 2008, determined from the noise level between 5 Hz and 20 Hz in the time-ordered data stream (TOD), is 32 micro-Kelvin sqrt{s} in CMB units. Atmospheric brightness fluctuations constitute the main contaminant in the data and dominate the detector noise covariance at low frequencies in the TOD. The maps were made by solving the least-squares problem using the Preconditioned Conjugate Gradient method, incorporating the details of the detector and noise correlations. Cross-correlation with WMAP sky maps, as well as analysis from simulations, reveal that our maps are unbiased at multipoles ell > 300. This paper accompanies the public release of the 148 GHz southern stripe maps from 2008. The techniques described here will be applied to future maps and data releases.
Cite
@article{arxiv.1208.0050,
title = {The Atacama Cosmology Telescope: Data Characterization and Map Making},
author = {Rolando Dünner and Matthew Hasselfield and Tobias A. Marriage and Jon Sievers and Viviana Acquaviva and Graeme E. Addison and Peter A. R. Ade and Paula Aguirre and Mandana Amiri and John William Appel and L. Felipe Barrientos and Elia S. Battistelli and J. Richard Bond and Ben Brown and Bryce Burger and Erminia Calabrese and Jay Chervenak and Sudeep Das and Mark J. Devlin and Simon R. Dicker and W. Bertrand Doriese and Joanna Dunkley and Thomas Essinger-Hileman and Ryan P. Fisher and Megan B. Gralla and Joseph W. Fowler and Amir Hajian and Mark Halpern and Carlos Hernández-Monteagudo and Gene C. Hilton and Matt Hilton and Adam D. Hincks and Renée Hlozek and Kevin M. Huffenberger and David H. Hughes and John P. Hughes and Leopoldo Infante and Kent D. Irwin and Jean Baptiste Juin and Madhuri Kaul and Jeff Klein and Arthur Kosowsky and Judy M. Lau and Michele Limon and Yen-Ting Lin and Thibaut Louis and Robert H. Lupton and Danica Marsden and Krista Martocci and Phil Mauskopf and Felipe Menanteau and Kavilan Moodley and Harvey Moseley and Calvin B. Netterfield and Michael D. Niemack and Michael R. Nolta and Lyman A. Page and Lucas Parker and Bruce Partridge and Hernán Quintana and Beth Reid and Neelima Sehgal and Blake D. Sherwin and David N. Spergel and Suzanne T. Staggs and Daniel S. Swetz and Eric R. Switzer and Robert Thornton and Hy Trac and Carole Tucker and Ryan Warne and Grant Wilson and Ed Wollack and Yue Zhao},
journal= {arXiv preprint arXiv:1208.0050},
year = {2015}
}
Comments
20 pages, 18 figures, 6 tables, an ACT Collaboration paper