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Improving the LSST dithering pattern and cadence for dark energy studies

Carroll, Christopher M. et al.
Eric Gawiser ; Peter L. Kurczynski ; Rachel A. Bailey ; Rahul Biswas ; David Cinabro ; Saurabh W. Jha ; R. Lynne Jones ; K. Simon Krughoff ; Aneesa Sonawalla ; W. Michael Wood-Vasey
Publication Date: 
Wednesday, August 6, 2014
Conference Papers
SPIE Proceedings
Page #: 
The Large Synoptic Survey Telescope (LSST) will explore the entire southern sky over 10 years starting in 2022 with unprecedented depth and time sampling in six filters, ugrizy. Artificial power on the scale of the 3.5 deg LSST field-of-view will contaminate measurements of baryonic acoustic oscillations (BAO), which fall at the same angular scale at redshift z ~ 1. Using the HEALPix framework, we demonstrate the impact of an “un- dithered” survey, in which 17% of each LSST field-of-view is overlapped by neighboring observations, generating a honeycomb pattern of strongly varying survey depth and significant artificial power on BAO angular scales. We find that adopting large dithers (i.e., telescope pointing o sets) of amplitude close to the LSST field-of-view radius reduces artificial structure in the galaxy distribution by a factor of ~10. We propose an observing strategy utilizing large dithers within the main survey and minimal dithers for the LSST Deep Drilling Fields. We show that applying various magnitude cutos can further increase survey uniformity. We find that a magnitude cut of r < 27:3 removes significant spurious power from the angular power spectrum with a minimal reduction in the total number of observed galaxies over the ten-year LSST run. We also determine the effectiveness of the observing strategy for Type Ia SNe and predict that the main survey will contribute ~100,000 Type Ia SNe. We propose a concentrated survey where LSST observes one-third of its main survey area each year, increasing the number of main survey Type Ia SNe by a factor of ~1.5, while still enabling the successful pursuit of other science drivers.
Bibtex reference: 
@INPROCEEDINGS{2014SPIE.9149E..0CC, author = {{Carroll}, C.~M. and {Gawiser}, E. and {Kurczynski}, P.~L. and {Bailey}, R.~A. and {Biswas}, R. and {Cinabro}, D. and {Jha}, S.~W. and {Jones}, R.~L. and {Krughoff}, K.~S. and {Sonawalla}, A. and {Wood-Vasey}, W.~M.}, title = "{Improving the LSST dithering pattern and cadence for dark energy studies}", booktitle = {Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series}, year = 2014, series = {Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series}, volume = 9149, archivePrefix = "arXiv", eprint = {1501.04733}, primaryClass = "astro-ph.IM", month = aug, eid = {91490C}, pages = {91490C}, doi = {10.1117/12.2057267}, adsurl = {}, adsnote = {Provided by the SAO/NASA Astrophysics Data System} }

Financial support for LSST comes from the National Science Foundation (NSF) through Cooperative Agreement No. 1258333, the Department of Energy (DOE) Office of Science under Contract No. DE-AC02-76SF00515, and private funding raised by the LSST Corporation. The NSF-funded LSST Project Office for construction was established as an operating center under management of the Association of Universities for Research in Astronomy (AURA).  The DOE-funded effort to build the LSST camera is managed by the SLAC National Accelerator Laboratory (SLAC).
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