The Hyper Suprime-Cam SSP survey: Overview and survey design

Hyper Suprime-Cam (HSC) is a wide-field imaging camera on the prime focus of the 8.2-m Subaru telescope on the summit of Mauna Kea in Hawaii. A team of scientists from Japan, Taiwan, and Princeton University is using HSC to carry out a 300-night multi-band imaging survey of the high-latitude sky. The survey includes three layers: the Wide layer will cover 1400 deg2 in five broad bands (grizy), with a 5 σ point-source depth of r ≈ 26. The Deep layer covers a total of 26 deg2 in four fields, going roughly a magnitude fainter, while the UltraDeep layer goes almost a magnitude fainter still in two pointings of HSC (a total of 3.5 deg2). Here we describe the instrument, the science goals of the survey, and the survey strategy and data processing. This paper serves as an introduction to a special issue of the Publications of the Astronomical Society of Japan, which includes a large number of technical and scientific papers describing results from the early phases of this survey

Transboundary Secondary Organic Aerosol in Western Japan Indicated by the δ¹³C of Water-Soluble Organic Carbon and the <i>m</i>/<i>z</i> 44 Signal in Organic Aerosol Mass Spectra

The stable carbon isotope ratio (δ¹³C) of low-volatile water-soluble organic carbon (LV-WSOC) was measured in filter samples of total suspended particulate matter, collected every 24 h in the winter of 2010 at an urban site and two rural sites in western Japan. Concentrations of the major chemical species in fine aerosol (<1.0 μm) were also measured in real time by aerosol mass spectrometers. The oxidation state of organic aerosol was evaluated using <i>f</i>₄₄; i.e., the proportion of the signal at <i>m</i>/<i>z</i> 44 (CO₂⁺ ions from the carboxyl group) to the sum of all <i>m</i>/<i>z</i> signals in the organic mass spectra. A strong correlation between LV-WSOC and <i>m</i>/<i>z</i> 44 concentrations was observed, which suggested that LV-WSOC was likely to be associated with carboxylic acids in fine aerosol. Plots of δ¹³C of LV-WSOC versus <i>f</i>₄₄ showed random variation at the urban site and systematic trends at the rural sites. The systematic trends qualitatively agreed with a simple binary mixture model of secondary organic aerosol with background LV-WSOC with an <i>f</i>₄₄ of ∼0.08 and δ¹³C of −17‰ or higher. Comparison with reference values suggested that the source of background LV-WSOC was likely to be primary emissions associated with C₄ plants