Constance E. Walker

Learn More
Despite constituting a widespread and significant environmental change, understanding of artificial nighttime skyglow is extremely limited. Until now, published monitoring studies have been local or regional in scope, and typically of short duration. In this first major international compilation of monitoring data we answer several key questions about(More)
The skyglow produced by artificial lights at night is one of the most dramatic anthropogenic modifications of Earth's biosphere. The GLOBE at Night citizen science project allows individual observers to quantify skyglow using star maps showing different levels of light pollution. We show that aggregated GLOBE at Night data depend strongly on artificial(More)
We have observed the 12 CO J=2-1, 13 CO J=2-1, and 12 CO J=3-2 lines in a sample of seven giant molecular clouds in the Local Group spiral galaxy M33 using the James Clerk Maxwell Telescope. The 12 CO/ 13 CO J=2-1 line ratio is constant across the entire sample, while the observed 12 CO J=3-2/J=2-1 line ratio has a weak dependence on the star formation(More)
Groundwater under the direct influence of surface water (GWUDISW) is of concern in communities where growing public demand on groundwater resources has resulted in increased withdrawals and hydraulic stress near surface water bodies. Under these conditions, contaminants such as methyl-tert butyl ether (MTBE) and biological materials have been detected in(More)
We have obtained 12 CO and 13 CO J=1-0 observations of the nearby spiral galaxy M33 to try to resolve the long-standing discrepancy between 12 CO/ 13 CO line ratios measured in Galactic giant molecular clouds and external galaxies. Interferometer maps of the molecular cloud MC20 give a 12 CO/ 13 CO line ratio of 7:52:1, which agrees reasonably well with the(More)
  • 1