High-resolution imaging at the SOAR telescope

TL;DR

This paper evaluates high-resolution imaging techniques at the SOAR telescope, comparing adaptive optics, lucky imaging, and speckle interferometry, to assess their effectiveness in reaching diffraction-limited resolution for stellar observations.

Contribution

It provides a comparative analysis of different high-resolution imaging methods using a fast electron-multiplication camera at the SOAR telescope, including practical results and potential improvements.

Findings

Partial AO correction improves resolution but is limited by vibrations.

Lucky imaging and speckle interferometry can approach diffraction limit under certain conditions.

Resolution of the astrometric companion to Zeta Aqr B was tentatively achieved.

Abstract

Bright single and binary stars were observed at the 4.1-m telescope with a fast electron-multiplication camera in the regime of partial turbulence correction by the visible-light adaptive optics system. We compare the angular resolution achieved by simple averaging of AO-corrected images (long-exposure), selection and re-centering (shift-and-add or "lucky" imaging) and speckle interferometry. The effect of partial AO correction, vibrations, and image post-processing on the attained resolution is shown. Potential usefulness of these techniques is evaluated for reaching the diffraction limit in ground-based optical imaging. Measurements of 75 binary stars obtained during these tests are given and objects of special interest are discussed. We report tentative resolution of the astrometric companion to Zeta Aqr B. A concept of advanced high-resolution camera is outlined.