The Real Time Mesoscale Analysis (RTMA), a two-dimensional variational analysis algorithm, is used to provide hourly analyses of surface sensible weather elements for situational awareness at spatial resolutions of 3 km over Alaska. In this work we focus on the analysis of horizontal visibility in Alaska, which is a region prone to weather related aviation accidents that are in part due to a relatively sparse observation network. In this study we evaluate the impact of assimilating estimates of horizontal visibility derived from a novel network of web cameras in Alaska with the RTMA. Results suggest that the web camera-derived estimates of visibility can capture low visibility conditions and have the potential to improve the RTMA visibility analysis under conditions of low instrument flight rules and instrument flight rules.

Hill (Twin Research and Human Genetics, Vol. 21, 2018, 84–88) presented a critique of our recently published paper in Cell Reports entitled ‘Large-Scale Cognitive GWAS Meta-Analysis Reveals Tissue-Specific Neural Expression and Potential Nootropic Drug Targets’ (Lam et al., Cell Reports, Vol. 21, 2017, 2597–2613). Specifically, Hill offered several interrelated comments suggesting potential problems with our use of a new analytic method called Multi-Trait Analysis of GWAS (MTAG) (Turley et al., Nature Genetics, Vol. 50, 2018, 229–237). In this brief article, we respond to each of these concerns. Using empirical data, we conclude that our MTAG results do not suffer from ‘inflation in the FDR [false discovery rate]’, as suggested by Hill (Twin Research and Human Genetics, Vol. 21, 2018, 84–88), and are not ‘more relevant to the genetic contributions to education than they are to the genetic contributions to intelligence’.

We discuss observations of Sagittarius A* with NACO@VLT in K-band and recent synchronous observations with NIRC2@Keck II and OSIRIS@Keck I in L′-band and H-band, respectively. The variability of Sagittarius A* in the near infrared is a continuous one-state process that can be described by a pure red-noise process having a timescale of a few hours. We describe this process and its properties in detail. Our newest observations with the Keck telescopes represent the first truly synchronous high cadence data set to test for time variability of the spectral index within the near infrared. We discovered a time-variable spectral index that might be interpreted as a time lag of the L′-band with respect to the H-band.

We report new precision measurements of the properties of our Galaxy's supermassive black hole. Based on astrometric (1995-2007) and radial velocity (2000-2007) measurements from the W. M. Keck 10 meter telescopes, the Keplerian orbital parameters for the short period star S0-2 imply a distance of 8.3 ± 0.3 kpc, an enclosed mass of 4.8 ± 0.3 × 106M⊙, and a black hole position that is localized to within ± 1 mas and that is consistent with the position of SgrA*-IR. Astrometric bias from source confusion is identified as a significant source of systematic error and is accounted for in this study. Our black hole mass and distance are significantly higher than previous estimates. The higher mass estimate brings the Galaxy into better agreement with the relationship between the mass of the central black hole and the velocity dispersion of the host galaxy's bulge observed for nearby galaxies. It also raises the orbital period of the innermost stable orbit of a non-spinning black hole to 38 min and increases the Rauch-Tremaine resonant relaxation timescales for stars in the vicinity of the central black hole. Taking the black hole's distance as a measure of R0, which is a fundamental scale for our Galaxy, and other measurements of galactic constants, we infer a value of the Galaxy's local rotation speed (θ0) of 255 ± 13 km s−1. With the precisions of the astrometric and radial velocity measurements that are now possible with Laser Guide Star Adaptive Optics, we expect to be able to measure Ro to an accuracy of ~ 1% within the next ten years, which could considerably reduce the uncertainty in the cosmological distance ladder.