The Atacama Cosmology Telescope: A Catalog of >4000 Sunyaev–Zel’dovich Galaxy Clusters

We present a catalog of 4195 optically confirmed Sunyaev–Zel'dovich (SZ) selected galaxy clusters detected with signal-to-noise ratio >4 in 13,211 deg2 of sky surveyed by the Atacama Cosmology Telescope (ACT). Cluster candidates were selected by applying a multifrequency matched filter to 98 and 150 GHz maps constructed from ACT observations obtained from 2008 to 2018 and confirmed using deep, wide-area optical surveys. The clusters span the redshift range 0.04 1 clusters, and a total of 868 systems are new discoveries. Assuming an SZ signal versus mass-scaling relation calibrated from X-ray observations, the sample has a 90% completeness mass limit of M500c > 3.8 × 1014 M⊙, evaluated at z = 0.5, for clusters detected at signal-to-noise ratio >5 in maps filtered at an angular scale of 2farcm4. The survey has a large overlap with deep optical weak-lensing surveys that are being used to calibrate the SZ signal mass-scaling relation, such as the Dark Energy Survey (4566 deg2), the Hyper Suprime-Cam Subaru Strategic Program (469 deg2), and the Kilo Degree Survey (825 deg2). We highlight some noteworthy objects in the sample, including potentially projected systems, clusters with strong lensing features, clusters with active central galaxies or star formation, and systems of multiple clusters that may be physically associated. The cluster catalog will be a useful resource for future cosmological analyses and studying the evolution of the intracluster medium and galaxies in massive clusters over the past 10 Gyr

PVC/PVP/SrTiO3 polymer blend nanocomposites as potential materials for optoelectronic applications

This paper presents, for the first time, the preparation and study of the thermal decomposition and optical properties of PVC/PVP/SrTiO3 polymer blend nanocomposites. The polymer films were characterized using X-ray diffraction (XRD), Fourier transform infra-red spectroscopy (FTIR), Raman, thermogravimetric analysis (TGA), and optical spectroscopy techniques. XRD spectra indicated semicrystalline structure of the PVC/PVP polymer blend and revealed cubic crystal structure of the SrTiO3 nanoparticles. The lattice constant of SrTiO3 was found to decrease from 2.79 to 2.75 Å upon increasing the concentration of the SrTiO3 nanoparticles in the blend to 0.6 wt%. The FTIR and Raman spectra revealed the strong interaction between PVC/PVP polymer blend and SrTiO3. The TGA analysis showed a slight enhancement of the polymer blend thermal stability. Moreover, the thermal kinetic parameters, such as activation energy, entropy and Gibbs free energy, of the polymer nanocomposites were lower than those of the pure PVC/PVP blend counterpart. The addition of SrTiO3 increased the optical absorption, energy gap, and linear refractive index. Furthermore, the optical susceptibility and nonlinear refractive index were significantly improved. For all polymer blends, a fluorescence peak appeared at a wavelength of 485 nm. These outcomes qualify the PVC/PVP/SrTiO3 polymer blend nanocomposites for optoelectronic applications

The Sloan Digital Sky Survey monitor telescope pipeline

The photometric calibration of the Sloan Digital Sky Survey (SDSS) is a multi-step process which involves data from three different telescopes: the 1.0-m telescope at the US Naval Observatory (USNO), Flagstaff Station, Arizona (which was used to establish the SDSS standard star network); the SDSS 0.5-m Photometric Telescope (PT) at the Apache Point Observatory (APO), New Mexico (which calculates nightly extinctions and calibrates secondary patch transfer fields); and the SDSS 2.5-m telescope at APO (which obtains the imaging data for the SDSS proper). In this paper, we describe the Monitor Telescope Pipeline, MTPIPE, the software pipeline used in processing the data from the single-CCD telescopes used in the photometric calibration of the SDSS (i.e., the USNO 1.0-m and the PT). We also describe transformation equations that convert photometry on the USNO-1.0m u'g'r'i'z' system to photometry the SDSS 2.5m ugriz system and the results of various validation tests of the MTPIPE software. Further, we discuss the semi-automated PT factory, which runs MTPIPE in the day-to-day standard SDSS operations at Fermilab. Finally, we discuss the use of MTPIPE in current SDSS-related projects, including the Southern u'g'r'i'z' Standard Star project, the u'g'r'i'z' Open Star Clusters project, and the SDSS extension (SDSS-II).Astronom