High-Efficiency Lucky Imaging

TL;DR

This paper introduces a Fourier space selection method for Lucky Imaging that significantly improves frame selection efficiency, enabling routine high-resolution ground-based astronomical imaging with larger isoplanatic patches.

Contribution

A novel Fourier space selection technique for Lucky Imaging that enhances efficiency and extends the usable field of view compared to traditional methods.

Findings

Fourier space selection increases frame retention rates.

High-resolution images with large isoplanatic patches are achievable routinely.

The method improves sensitivity to faint reference stars.

Abstract

Lucky Imaging is now an established observing procedure that delivers near diffraction-limited images in the visible on ground-based telescopes up to ~2.5 m in diameter. Combined with low order adaptive optics it can deliver resolution several times better than that of the Hubble Space Telescope. Many images are taken at high speed as atmospheric turbulent effects appear static on these short timescales. The sharpest images are selected, shifted and added to give a much higher resolution than is normally possible in ground-based long exposure time observations. The method is relatively inefficient as a significant fraction of the frames are discarded because of their relatively poor quality. This paper shows that a new Lucky Imaging processing method involving selection in Fourier space can substantially improve the selection percentages. The results show that high resolution images with a large isoplanatic patch size may be obtained routinely both with conventional Lucky Imaging and with the new Lucky Fourier method. Other methods of improving the sensitivity of the method to faint reference stars are also described.