GPS Measurements of Precipitable Water Vapor Can Improve Survey Calibration: A Demonstration from KPNO and the Mayall z-band Legacy Survey

Abstract Dual-band Global Positioning Satellite (GPS) measurements of precipitable water vapor (PWV) at the Kitt Peak National Observatory predict overall per-image sensitivity Mayall z -band Legacy Survey (MzLS). The variation in brightness individual stars is strongly correlated with measured PWV and color star. Synthetic stellar spectra through TAPAS transmission models successfully observed PWV-induced photometric variation. We find that absorption can be well approximated by a linear relationship (airmass × PWV) 0.6 present an update on traditional treatment literature. MzLS zero-point electrons s ?1 varies normalized-mean absolute deviation 61 mmag. accounts 23 mmag this decreases 40 per effective mm PWV. gray offset portion corrected calibration to reference catalog. But relative error between blue ( r ? < 0.5 mag) versus red (1.2 mag ) increases 0.3–2 argue GPS systems provide more precise than using differential different colors recommend observatories install dual-band as low-maintenance, low-cost, auxiliary system. extend our results need for well-calibrated presenting calculations impact three science cases interest: photometry, supernova cosmology, quasar identification variability.