Spatial and Temporal Stability of Airglow Measured in the Meinel Band Window at 1191.3 nm

TL;DR

This study measures the stability of airglow at 1191.3 nm, demonstrating that near-infrared line intensity mapping from ground-based sites is feasible due to stable noise performance over several hours.

Contribution

The paper introduces a new instrument and provides detailed analysis of airglow fluctuations, confirming the feasibility of ground-based near-IR line intensity mapping.

Findings

Absolute sky brightness measured at 5330 +/- 30 nW m^-2 sr^-1

No evidence of temporal instability in the inter-line continuum

Instrument noise performance remains stable over several hours

Abstract

We report on the temporal and spatial fluctuations in the atmospheric brightness in the narrow band between Meinel emission lines at 1191.3 nm using an R=320 near-infrared instrument. We present the instrument design and implementation, followed by a detailed analysis of data taken over the course of a night from Table Mountain Observatory. The absolute sky brightness at this wavelength is found to be 5330 +/- 30 nW m^-2 sr^-1, consistent with previous measurements of the inter-band airglow at these wavelengths. This amplitude is larger than simple models of the continuum component of the airglow emission at these wavelengths, confirming that an extra emissive or scattering component is required to explain the observations. We perform a detailed investigation of the noise properties of the data and find no evidence for a noise component associated with temporal instability in the inter-line continuum. This result demonstrates that in several hours of ~100s integrations the noise performance of the instrument does not appear to significantly degrade from expectations, giving a proof of concept that near-IR line intensity mapping may be feasible from ground-based sites.