Performance of Kitt Peak's Mayall 4-meter telescope during DESI commissioning

Aaron M. Meisner, Behzad Abareshi, Arjun Dey, Connie Rockosi, Richard Joyce, David Sprayberry, Robert Besuner, Klaus Honscheid, David Kirkby, Hui Kong, Martin Landriau, Michael Levi, Ting Li, Bob Marshall, Paul Martini, Ashley Ross, David Brooks, Peter Doel, Yutong Duan, Enrique GaztañagaChristophe Magneville, Francisco Prada, Michael Schubnell, Gregory Tarlé

Research output: Chapter in Book/Report/Conference proceedingConference contribution


In preparation for the Dark Energy Spectroscopic Instrument (DESI), a new top end was installed on the Mayall 4-meter telescope at Kitt Peak National Observatory. The refurbished telescope and the DESI instrument were successfully commissioned on sky between 2019 October and 2020 March. Here we describe the pointing, tracking and imaging performance of the Mayall telescope equipped with its new DESI prime focus corrector, as measured by six guider cameras sampling the outer edge of DESI's focal plane. Analyzing ∼500,000 guider images acquired during commissioning, we find a median delivered image FWHM of 1.1 arcseconds (in the r-band at 650 nm), with the distribution extending to a best-case value of ∼0.6 arcseconds. The point spread function is well characterized by a Moffat profile with a power-law index of β ≈ 3.5 and little dependence of β on FWHM. The shape and size of the PSF delivered by the new corrector at a field angle of 1.57 degrees are very similar to those measured with the old Mayall corrector on axis. We also find that the Mayall achieves excellent pointing accuracy (several arcseconds RMS) and minimal open-loop tracking drift (< 1 milliarcsecond per second), improvements on the telecope's pre-DESI performance. In the future, employing DESI's active focus adjustment capabilities will likely further improve the Mayall/DESI delivered image quality.

Original languageEnglish
Title of host publicationGround-Based and Airborne Instrumentation for Astronomy VIII
EditorsChristopher J. Evans, Julia J. Bryant, Kentaro Motohara
PublisherSPIE Press
ISBN (Electronic)9781510636811
Publication statusPublished - 13 Dec 2020
EventGround-Based and Airborne Instrumentation for Astronomy VIII 2020 - Virtual, Online, United States
Duration: 14 Dec 202022 Dec 2020

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X


ConferenceGround-Based and Airborne Instrumentation for Astronomy VIII 2020
Country/TerritoryUnited States
CityVirtual, Online


  • DESI
  • Kitt peak national observatory
  • Mayall telescope
  • UKRI
  • STFC

Cite this