Global Extinction: Combined Gemini North and South GMOS Photometry Relative to the Gaia Catalog, and Long-Term Atmospheric Change

TL;DR

This study analyzes long-term atmospheric effects on photometry from Gemini GMOS data compared to Gaia, revealing a gradual increase in atmospheric extinction over two decades linked to climate change.

Contribution

It provides a comprehensive analysis of atmospheric extinction trends over 18 years using archival Gemini GMOS data and Gaia comparison, highlighting climate-related impacts.

Findings

Detected a ~2 mmag per decade increase in atmospheric extinction.

Identified a significant extinction event in 2009.

Correlated extinction trends with climate change indicators.

Abstract

Effects of long-term atmospheric change were looked for in photometry employing the Gemini North and South twin Multi-Object Spectrograph (GMOS-N and GMOS-S) archival data. The whole GMOS imaging database, beginning from 2003, was compared against the all-sky Gaia object catalog, yielding ~10^6 Sloan r'-filter samples, ending in 2021. These were combined with reported sky and meteorological conditions, versus a simple model of the atmosphere plus cloud together with simulated throughputs. One exceptionally extincted episode in 2009 is seen, as is a trend (similar at both sites) of about 2 mmag worsening attenuation per decade. This is consistent with solar-radiance transmissivity records going back over six decades, aerosol density measurements, and more than 0.2 deg C per decade rise in global air temperature, which has implications for calibration of historic datasets or future surveys.