# The EMCCD-Based Speckle Interferometer of the BTA 6-m Telescope: Description and First Results

## TL;DR

This paper describes a new speckle interferometer for the BTA 6-m telescope using an EMCCD detector, enabling high-speed, high-resolution imaging of stars for diffraction-limited observations.

## Contribution

Introduction of a novel EMCCD-based speckle interferometer with improved speed and sensitivity for the BTA telescope, achieving diffraction-limited imaging of 15th magnitude stars.

## Key findings

- High quantum efficiency (93%) of the new detector.
- Ability to capture up to 20 speckle images per second.
- Potential for diffraction-limited imaging of 15th magnitude stars.

## Abstract

The description is given for the speckle interferometer of the BTA 6-m telescope of the SAO RAS based on a new detector with an electron multiplication CCD. The main components of the instrument are microscope objectives, interference filters and atmospheric dispersion correction prisms. The PhotonMAX-512B CCD camera using a back-illuminated CCD97 allows up to 20 speckle images (with 512$\times$512 pix resolution) per second storage on the hard drive. Due to high quantum efficiency (93% in the maximum at 550 nm), and high transmission of its optical elements, the new camera can be used for diffraction-limited (0.02$''$) image reconstruction of $15^{m}$ stars under good seeing conditions. The main advantages of the new system over the previous generation BTA speckle interferometer are examined.