# The Enhanced Resolution Imager and Spectrograph for the VLT

**Authors:** R. Davies, O. Absil, G. Agapito, A. Agudo Berbel, A. Baruffolo, V. Biliotti, M. Bonaglia, M. Bonse, R. Briguglio, P. Campana, Y. Cao, L. Carbonaro, A. Cortes, G. Cresci, Y. Dallilar, F. Dannert, R. J. De Rosa, M. Deysenroth, I. Di Antonio, A. Di Cianno  
**arXiv:** [2304.02343](https://arxiv.org/abs/2304.02343)  
**Date:** 2023-04-05  
**Summary page:** https://www.summarizepaper.com/en/paper/2304.02343v1/

## Key points

- ERIS is a state-of-the-art instrument installed at the Cassegrain focus of UT4 at the VLT.
- ERIS combines the functionality of two instruments and improves on their performance by extending and enhancing fundamental diffraction limited imaging and spectroscopy capability for the VLT.
- ERIS provides several observational modes including integral field spectroscopy, imaging with high contrast imaging options, and longslit spectroscopy.
- ERIS features a wavefront sensing module for natural and laser guide stars which utilizes the Adaptive Optics Facility to improve image quality in real time.
- The commissioning of ERIS during 2022 has made it available to astronomers who can use its improved capabilities to study celestial objects with unprecedented detail.
- Its successful implementation marks a significant milestone in astronomical instrumentation technology.
- ERIS will contribute significantly to our understanding of various astrophysical phenomena such as star formation, galaxy evolution, black hole dynamics, and exoplanet characterization.
- The development of ERIS involved contributions from numerous researchers across multiple institutions who worked together to design and build this cutting-edge instrument.

## Summary

ERIS, the Enhanced Resolution Imager and Spectrograph, is a state-of-the-art instrument installed at the Cassegrain focus of UT4 at the VLT. It combines the functionality of two instruments that were being maintained beyond their operational lifetimes and improves on their performance by extending and enhancing the fundamental diffraction limited imaging and spectroscopy capability for the VLT. ERIS provides several observational modes including integral field spectroscopy at 1-2.5 μm, imaging at 1-5 μm with high contrast imaging options, and longslit spectroscopy at 3-4 μm. Additionally, it features a wavefront sensing module for natural and laser guide stars which utilizes the Adaptive Optics Facility to improve image quality in real time. The commissioning of ERIS during 2022 has made it available to astronomers who can use its improved capabilities to study celestial objects with unprecedented detail. Its successful implementation marks a significant milestone in astronomical instrumentation technology and will contribute significantly to our understanding of various astrophysical phenomena such as star formation, galaxy evolution, black hole dynamics, and exoplanet characterization. The development of ERIS involved contributions from numerous researchers across multiple institutions who worked together to design and build this cutting-edge instrument.