| Alternative names | Mayall 4-meter Telescope |
|---|---|
| Location(s) | Arizona |
| Coordinates | 31°57′48″N 111°36′00″W / 31.9634°N 111.6°W / 31.9634; -111.6 |
| Altitude | 2,120 m (6,960 ft) |
| First light | February 27, 1973[1] |
| Discovered | Methane ice on Pluto |
| Diameter | 4 m (13 ft 1 in) |
| Collecting area | 11.4 m2 (123 sq ft) |
| Website | noirlab |
| | |


The Nicholas U. Mayall Telescope, also known as the Mayall 4-meter Telescope, is a four-meter (158 inches) reflector telescope located at the Kitt Peak National Observatory in Arizona and named after Nicholas U. Mayall. It saw first light on February 27, 1973, and was the second-largest telescope in the world at that time.[2] Initial observers included David Crawford, Nicholas Mayall, and Arthur Hoag.[2] It was dedicated on June 20, 1973 after Mayall's retirement as director.[2] The mirror has an f/2.7 hyperboloidal shape. It is made from a two-foot (61 cm (24 in)) thick fused quartz disk that is supported in an advanced-design mirror cell. The prime focus has a 3.2 degree field of view, making it six times larger than that of the Hale reflector. It is host to the Dark Energy Spectroscopic Instrument[3]. The identical Víctor M. Blanco Telescope was later built at Cerro Tololo Inter-American Observatory, in Chile.[4]
Planning & construction
In 1961, after work had moved forward on other telescopes, Mayall proposed an even larger 150-inch mirror telescope for Kitt Peak.[5] Site construction began in 1968 and by 1971 the mirror was delivered to the site.[6] The mirror was made by Owens-Illinois[6] and made of fused quartz, valued for its low coefficient of thermal expansion. The blank was ground at the Kitt Peak optical lab.[5]
The telescope primary mirror is designed to function as the first element in a Ritchey–Chrétien optical design.[7] The telescope was originally designed with three focal point options: the prime focus, a wide-field R/C focus, and a coudé focus.[8]
The telescope was dedicated in the summer of 1973, at which time it was the second largest telescope by aperture in the world.[9] The telescope was named after Mayall who was the director of Kitt Peak National Observatory for over a decade.[9]
Instruments

Examples of instruments over its lifetime include various spectrographs, Cryogenic Camera, the Phoenix spectrometer, and the DLIRIM.[8]
The KNPO Mosaic camera was installed in 1998, and was designed for the prime focus.[10] This camera had eight 2048 × 4096 CCD sensors.[10] This led to another camera Mosaic II for the CTIO 4-m telescope in the southern hemisphere.[10]
- Mosaic3
Mosaic3 was an imaging camera for the Mayall telescope.[11] This prime focus camera was used for a 3-band survey in support of the upcoming DESI instrument.[11]
- Fourier Transform Spectrograph
One instrument used with telescope was the Fourier Transform Spectrograph.[12] The FTS was used between 1975 and 1995, creating an archive of recorded spectra.[13] It was noted for collecting infrared spectrum before the advent of infrared imaging arrays.[13]
Over the time of its operation 10,000 spectra were taken of 800 different astronomical targets, and these were made available in the SpArc data archive in the early 21st century.[13]
- DESI
An instrument designed to help understand dark energy, installation of the Dark Energy Spectroscopic Instrument (DESI) was completed in late 2019.[14] Very little is known about dark energy, the supposed pressure responsible for the accelerating expansion rate of the universe.
DESI has five thousand fiber optic sensors, each one being robotically targetable at the focal plane.[14][15] Planned to examine the nature of millions of galaxies and quasars, the instrument has been a decade in construction and features contributions from hundreds of researchers.[14]
DESI achieved first light in 2019 and completed commissioning in March 2020.[16] Following delays associated with the COVID-19 pandemic, DESI officially began its five-year main survey on 14 May 2021.[17] The originally planned five-year survey was completed on 21 April 2026 after obtaining spectra and redshifts for more than 45 million galaxies and quasars, producing the largest high-resolution three-dimensional map of the universe assembled to that date.[18] Following completion of the primary survey, DESI transitioned into an extended survey program targeting additional regions of the sky and deeper observations of selected fields.
Discoveries & observations


In 1976 the Mayall Telescope was used to discover methane ice on planet Pluto.[19]
The FTS on Mayall was also used to study methane in the outer solar system in the 1980s.[20] The study included observation of monodeutered methane on Titan, a moon of Saturn noted for its thick atmosphere.[20] The Mayall was also one of several large telescopes that was part of a study of the Andromeda galaxy.[21] The observations helped understand the history of that galaxy, which in turn helps understand Earth's galaxy, the Milky Way.[21]
Contemporaries on commissioning
The Mayall was the second-largest telescope when inaugurated, between the Hale (5 m) and Shane (3 m).
Largest telescopes 1973:
| # | Name / Observatory |
Image | Aperture | Altitude | First Light |
Special advocate |
|---|---|---|---|---|---|---|
| 1 | Hale Telescope Palomar Obs. |
200 inch 508 cm |
1713 m (5620 ft) |
1949 | George Ellery Hale | |
| 2 | Mayall Telescope Kitt Peak National Obs. |
158 inch 401 cm |
2120 m (6955 ft) |
1973 | Nicholas Mayall | |
| 3 | Shane Telescope Lick Observatory |
120 inch 305 cm |
1283 m (4209 ft) |
1959 | Nicholas Mayall C. Donald Shane | |
| 4 | Harlan J. Smith Telescope McDonald Observatory |
107 in 270 cm |
2070 m (6791 ft) |
1968 | Harlan J. Smith |
Here is the dedication of the telescope with its namesake at the eyepiece:
Observation examples
Gallery
- DESI Installed on the Mayall 4-meter Telescope[22]
See also
References
- "The Mayall 4-Meter Telescope". NOAO. Archived from the original on January 7, 2020. Retrieved November 10, 2019.
- Lindsley, Dave; Edmondson, Frank; Kiani, Shiva (2008). "Celebrating 50 years; Kitt Peak National Observatory; Milestones at Kitt Peak" (PDF). NOAO. Archived from the original (PDF) on August 16, 2009. Retrieved October 24, 2009.
- "The Dark Energy Spectroscopic Instrument (DESI)". Astro2020: Decadal Survey on Astronomy and Astrophysics, APC white papers, no. 57; Bulletin of the American Astronomical Society. 2019. Retrieved 28 May 2026.
- Pasachoff, Jay M.; Chapman, Robert D.; Sinton, William M. (2014). "Telescope" (PDF). AccessScience. McGraw Hill Education: 14. doi:10.1036/1097-8542.681600.
- Leverington, David (2017). Observatories and Telescopes of Modern Times. Cambridge University Press. p. 24. ISBN 978-0-521-89993-2. LCCN 2016026406. OCLC 951563439. OL 27408337M. Archived from the original on October 15, 2021. Retrieved October 15, 2021.
- "Mayall 4-Meter Telescope: History". NOAO. Archived from the original on March 11, 2016. Retrieved November 7, 2019.
- Hoag, A. A. (May 1972). Laustsen, S.; Reiz, A. (eds.). Instrumentation for the KPNO and CTIO 4 meter reflectors (PDF). ESO/CERN Conference on Auxiliary Instrumentation for Large Telescopes. Geneva: ESO/CERN (published June 1972). p. 39. Bibcode:1972ailt.conf...39H. Archived (PDF) from the original on September 7, 2024.
- "Mayall 4-Meter Telescope: Instruments". NOAO. Archived from the original on March 11, 2016. Retrieved November 9, 2019.
- "Kitt Peak opens up its 158-inch telescope". Physics Today. Vol. 26, no. 5. American Institute of Physics. May 1973. p. 19. Bibcode:1973PhT....26e..19.. doi:10.1063/1.3128047. ISSN 0031-9228.
- Dey, Arjun; Valdes, Francisco (2014-03-01). "The Delivered Image Quality with the MOSAIC Cameras at the Kitt Peak 4 m Mayall and Cerro Tololo 4 m Blanco Telescopes". Publications of the Astronomical Society of the Pacific. 126 (937): 296. Bibcode:2014PASP..126..296D. doi:10.1086/675808. ISSN 1538-3873.
- Dey, Arjun; Rabinowitz, David; Karcher, Armin; Bebek, Chris; Baltay, Charles; Sprayberry, David; Valdes, Frank; Stupak, Bob; Donaldson, John; Emmet, Will; Hurteau, Tom (August 2016). Evans, Christopher J; Simard, Luc; Takami, Hideki (eds.). "Mosaic3: a red-sensitive upgrade for the prime focus camera at the Mayall 4m telescope". Ground-based and Airborne Instrumentation for Astronomy VI. 9908: 99082C. Bibcode:2016SPIE.9908E..2CD. doi:10.1117/12.2231488. S2CID 125204403.
- "Mayall 4-Meter Telescope: Instruments". www.noao.edu. Archived from the original on 2016-03-11. Retrieved 2019-11-07.
- Pilachowski, C. A.; Hinkle, K. H.; Young, M. D.; Dennis, H. B.; Gopu, A.; Henschel, R.; Hayashi, S. (January 2017). "An Archive of Spectra from the Mayall Fourier Transform Spectrometer at Kitt Peak". Publications of the Astronomical Society of the Pacific. 129 (972) 024006. arXiv:1610.02535. Bibcode:2017PASP..129b4006P. doi:10.1088/1538-3873/129/972/024006. ISSN 1538-3873. S2CID 119268330.
- "Kitt Peak Instrument To Study Dark Energy Begins Final Tests". KJZZ. 2019-10-31. Archived from the original on 2019-11-07. Retrieved 2019-11-07.
- Roberts, Glenn Jr. (28 October 2019). "DESI opens its 5000 eyes". symmetry magazine. Archived from the original on 2021-01-25. Retrieved 2019-11-07.
- Meisner, Aaron M.; et al. (2021). "Performance of Kitt Peak's Mayall 4-meter Telescope During DESI Commissioning". Publications of the Astronomical Society of the Pacific. 133 (1022): 064505. doi:10.1088/1538-3873/abec79.
- "Successful Start of Dark Energy Spectroscopic Instrument (DESI) Follows Record-Setting Trial Run". Lawrence Berkeley National Laboratory. May 17, 2021.
- "DESI Completes Planned 3D Map of the Universe and Continues Exploring". Lawrence Berkeley National Laboratory. April 15, 2026.
- Leverington, David (2003-05-29). Babylon to Voyager and Beyond: A History of Planetary Astronomy. Cambridge University Press. ISBN 978-0-521-80840-8. Archived from the original on 2021-10-15. Retrieved 2021-10-15.
- De Bergh, C.; Lutz, B. L.; Owen, T.; Chauville, J. (1988). "1988ApJ...329..951D Page 951". The Astrophysical Journal. 329: 951. Bibcode:1988ApJ...329..951D. doi:10.1086/166439.
- "Two Ancient Migration Events In The Andromeda Galaxy – SpaceRef". spaceref.com. 3 October 2019. Archived from the original on 2021-10-15. Retrieved 2019-11-09.
- "DESI Team Receives Project Management Excellence Award from Department of Energy". Retrieved December 2, 2021.
External links
Media related to Nicholas U. Mayall Telescope at Wikimedia Commons- The Mayall 4-meter Telescope - official site.
- Scale model of 4 meter
- Active Optics Upgrade
