CanariCam Mid-Infrared Drift Scanning: Improved Sensitivity and Spatial Resolution

TL;DR

This paper demonstrates that drift scanning with CanariCam on the GTC can improve sensitivity and spatial resolution in mid-infrared astronomy, offering an alternative to traditional chopping methods especially for large telescopes.

Contribution

It introduces a novel drift scanning technique for mid-infrared observations, reducing the need for secondary mirror chopping on large telescopes.

Findings

Successful drift scanning results with CanariCam on GTC

Potential for improved sensitivity and resolution in MIR observations

Implications for future large telescope instrumentation

Abstract

Ground-based mid-infrared (MIR) astronomical observations require the removal of the fast time variable components of (a) sky/background variation and (b) array background. Typically, this has been achieved through oscillating the telescope's secondary mirror a few times a second, a process termed "chopping". However, chopping reduces on-object photon collection time, imposes stringent demands on the secondary mirror, requires nodding of the telescope to remove the radiative offset imprinted by the chopping, and relies on an often-fixed chop-frequency regardless of the sky conditions in the actual observations. In the 30m telescope era, secondary mirror chopping is impracticable. However, if the sky and background is sufficiently stable, drift scanning holds the promise to remove the necessity of chopping. In this paper we report our encouraging drift scanning results using the CanariCam MIR instrument on the 10.4m Gran Telescopio Canarias and the implications to future instruments and experiments.