Extremely Large Telescope

Telescope Extremely Large Telescope
The main mirror and the tracking mechanism of the ELT
Type	Nasmyth mount reflector
Location	Cerro Armazones
height	3,060
Geographic coordinates	24 ° 35 ′ 20 ″  S , 70 ° 11 ′ 32 ″  W Coordinates: 24 ° 35 ′ 20 ″  S , 70 ° 11 ′ 32 ″  W
wavelength	optical, near and mid-infrared telescope
Aperture	39 m
construction time	10 years (planned)
Installation	2025
Specialty	Composed of 798 hexagonal mirror elements

The Extremely Large Telescope (ELT), previously the European Extremely Large Telescope (E-ELT), is a next-generation optical telescope under construction for the European Southern Observatory (ESO). It will have a main mirror 39 meters in diameter, which will be composed of 798 hexagonal mirror elements. This will make it the world's largest optical telescope.

history

The ESO Council during its meeting June 11-12, 2012

Nocturnal panorama image of Cerro Armazones (Chile), the location chosen in April 2010 for the Extremely Large Telescope

Construction site in October 2018

The planning was carried out in a three-year study ( phase B ), which the ESO approved in December 2006. An essential part of the phase is the work on a basic design for the telescope ( Baseline Reference Design ), the third version of which was in progress at the end of 2008. The phase is financed with EUR 57.3 million. The final design was assessed from September 21 to 24, 2010. In the run-up to the planning, the Overwhelmingly Large Telescope ( OWL with 100 meters, around 2030) had been designed in project studies, but it was found to be technically too demanding and financially risky. Another preliminary study, which extends further into the future, concerned the 50 m reflector telescope EURO 50 , the realization of which was also initially abandoned in favor of the ELT.

On December 9, 2011, the decision to build the telescope in the Chilean Atacama Desert was made , although not all 15 member states of the European Southern Observatory had secured the additional financing requirements for the device. The costs were put at 1.1 billion euros at the end of 2011. At a meeting of the ESO Council on June 11, 2012 at the ESO headquarters in Garching , the final decision on the construction was made with the necessary two-thirds majority of ESO members. It was determined that until at least 90 percent of the construction costs are approved by the member states, funds will initially only be released for preparatory work at the telescope's location. On March 3, 2013, the project was ratified by all participating countries.

Road construction began in March 2014, the official start of construction of the telescope was on June 19, 2014. In December 2014, over 90 percent of the total costs had already been secured by ESO. It is calculated at around 1 billion euros for the construction phase. The first light is planned for the year 2025.

In May 2016, the contract to build the dome and telescope structure was awarded to a consortium of Astaldi , Cimolai and EIE Group for around 400 million euros . The construction of the access road and the leveling of the construction site were completed by this time.

Construction of the telescope building began in May 2017.

In mid-June 2017, ESO announced that it would change the name of the telescope from European Extremely Large Telescope to Extremely Large Telescope to reflect the increasing number of international partners and the location in Chile.

After completion, operating costs of 30 million euros per year are expected.

Location

As a location, among others were Argentina , Chile , Morocco , Spain ( La Palma ), South Africa , Tibet , Greenland and the Antarctic considered. Above all, the first four options have been examined intensively. On April 26, 2010, Cerro Armazones , a mountain with a height of 3060 m, was selected as the location for the ELT. Cerro Armazones is located in the Chilean Atacama Desert , approx. 130 km south of the city of Antofagasta and only 20 km away from Cerro Paranal , the location of the Very Large Telescope (VLT). An agreement between ESO and the State of Chile in which 189 km² of land around the Cerro Armazones was transferred to ESO for the construction of the telescope and another 362 km² in the vicinity of the site was declared a protected area for 50 years to prevent impairment of the ELT To prevent light pollution or mining work was signed on October 13, 2011 in Santiago de Chile . Overall, the protection zone of the Paranal-Armazones complex was expanded to 1270 km². Due to the close proximity to the VLT, a large part of the infrastructure required to operate the telescopes can be used jointly.

Furnishing

The ELT with the dome open		... and from above (graphics)

design

With its 39.3 meter primary mirror system made up of 798 hexagonal segments, each 1.45 meters in diameter and only 5 centimeters thick, the telescope will capture 15 times more light than the telescopes at the time of its construction. An innovative five-mirror system allows the most advanced adaptive optics with more than 6000 actuators to correct atmospheric turbulence with a dynamic of more than 1000 actions per second. The overall structure will weigh about 2800  tons .

In January 2017, Schott AG was awarded the contract by ESO for the manufacture and delivery of the secondary mirror. Production of the 4.25 meter secondary mirror carrier (M2) has been running since May. After the glass mass has been cast and solidified, the mirror blank is thermally treated in order to convert the glass into the Zerodur glass ceramic .

In January 2018, Schott AG began producing the main mirror in Mainz. At full capacity, production of one mirror segment per day is expected.

Instruments

The telescope in Nasmyth mount will be equipped with several instruments, between which one should be able to switch within minutes. It will also be possible to position the telescope and the dome at different locations in the sky without any major delay.

Model of the EAGLE spectrograph

Eight different instruments and two focal modules are being designed with the aim of having at least two or three completed by the time of First Light and the others in the following ten years.

The following instruments are suggested:

• CODEX : an optical spectrograph with a spectral resolution of ${\displaystyle \textstyle R={\lambda \over \Delta \lambda }=135000}$

• EAGLE : a wide-angle multi-channel integral field near infrared (NIR) spectrograph, with adaptive multi-object optics
• EPICS : an optical / near infrared planetary camera with spectrograph with extreme adaptive optics
• HARMONI : an integral broadband field spectrograph
• METIS : camera and spectrograph for the middle infrared
• MICADO : a diffraction-limited camera for light in the near infrared
• OPTIMOS : an optical wide-angle multi-object spectrograph
• SIMPLE : a high resolution NIR spectrograph

The two focal modules that are under investigation:

• ATLAS : a laser tomographic module with adaptive optics
• MAORY : a module for multiple diffraction with adaptive optics

The instruments with adaptive optics can achieve an angular resolution of 0.005 arc seconds . This corresponds approximately to a distance of 1 AU at a distance of 600 light years. At a distance of 0.03 arc seconds (1 AU at a distance of 100 light years), the EPICS contrast already reaches 10 ⁸ , sufficient to see many planets next to the much brighter stars. For comparison: the human eye has a resolution of around 60 arc seconds.

Comparison with other large telescopes

Comparison of the mirror surfaces of optical telescopes

Surname	Aperture diameter (m)	Mirror surface (m²)	First light
ELT	39.3	978	2025
Thirty Meter Telescope (TMT)	30th	655	2027
Giant Magellan Telescope (GMT)	24.5	368	2029
Southern African Large Telescope (SALT)	11.1 x 9.8	79	2005
Keck Observatory	10.0	76	1990 , 1996
Gran Telescopio Canarias (GTC)	10.4	74	2007
Very Large Telescope (VLT)	8.2	4 × 50	1998 - 2000

See also

• List of the largest optical telescopes

Web links

Commons : Extremely Large Telescope  - collection of images, videos and audio files

• ESO European Extremely Large Telescope
• "ESO Council Gives Green Light to Detailed Study of the European Extremely Large Telescope" Spaceref.com

Individual evidence

1. ^ Preparing a Revolution. Retrieved March 29, 2012 . 
2. ↑ ESO project pages. Retrieved March 5, 2011 . 
3. ↑ Press release: ESO decides to build the world's largest optical telescope. Accessed June 12, 2012.
4. ↑ Great Britain confirms participation in the E-ELT
5. ^ Road to Armazones Started. ESO, March 14, 2014, accessed March 23, 2014 . 
6. ^ Official start of construction with a mountain blast. AstroNews, June 20, 2014, accessed June 23, 2014 . 
7. ^ Construction of Extremely Large Telescope Approved . In: Spaceref . 4th December 2014.
8. ^ Groundbreaking for the E-ELT . In: ESO . 19th June 2014.
9. ^ New baseline schedule for ESO's Extremely Large Telescope . In: ESO . January 8, 2019.
10. ↑ https://www.heise.de/newsticker/meldung/European-Extremely-Large-Telescope-ESO-verzut-teuersten-Bauauf-fuer-Riesenteleskop-3220331.html?hg=1&hgi=7&hgf=false
11. ↑ ESO signs the largest contract in the history of ground-based astronomy for the dome and telescope structure of the E-ELT. In: eso.org. May 25, 2016, accessed April 5, 2019 . 
12. ↑ Construction begins on world's largest telescope in Chilean desert. May 26, 2017. Retrieved May 26, 2017 . 
13. ↑ Renaming the E-ELT statement from ESO's Director General. June 13, 2017. Retrieved June 13, 2017 . 
14. ↑ Klaus Buttinger: With the largest mirror in the world in search of extraterrestrial life. Oberösterreichische Nachrichten, February 28, 2015, accessed on March 1, 2015 . 
15. ↑ - ( Memento of the original from September 24, 2009 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. 
16. ↑ E-ELT: Cerro Armazones in Chile will be the location of the largest optical telescope in the world. In: eso.org. April 26, 2010, accessed April 5, 2019 . 
17. ↑ ESO and Chile sign agreement on the E-ELT. Retrieved March 29, 2012 . 
18. ↑ Roberto Gilmozzi, Jason Spyromilio: The European Extremely Large Telescope (E-ELT) Archived from the original on May 1, 2014. Info: The archive link has been inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. In: The Messenger . No. 127, March 2007, pp. 11-19. bibcode : 2007Msngr.127 ... 11G . 
19. ↑ E-ELT TELESCOPE DESIGN . In: ESO . August 23, 2012. Accessed September 2015.
20. ↑ ESOcast 107 Light: Secondary Mirror of ELT Successfully Cast
21. ↑ The optical system of the ELT
22. ↑ [e-mail]: First ELT main mirror segments successfully cast. Retrieved January 10, 2018 (German). 
23. ↑ E-ELT instrumentation . Retrieved October 29, 2009.
24. ↑ Luca Pasquini et al .: Proceedings of SPIE . In: SPIE . Ground-based and Airborne Instrumentation for Astronomy II, No. CODEX: the high-resolution visual spectrograph for the E-ELT, 2008, pp. 70141I – 70141I – 9. doi : 10.1117 / 12.787936 .
25. ↑ CODEX - An ultra-stable, high-resolution optical spectrograph for the E-ELT . IAC. Retrieved November 29, 2012.
26. ↑ Jean-Gabriel Cuby et al .: Proceedings of SPIE Archived from the original on August 15, 2011. Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. In: SPIE . 7735: Ground-based and Airborne Instrumentation for Astronomy III, No. EAGLE: a MOAO fed multi-IFU NIR workhorse for E-ELT, 2010, pp. 77352D – 77352D – 15. bibcode : 2010SPIE.7735E..80C . doi : 10.1117 / 12.856820 . Retrieved November 29, 2012. 
27. ^ EAGLE: the Extremely Large Telescope Adaptive Optics for Galaxy Evolution instrument . Archived from the original on October 4, 2010. Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. Retrieved October 29, 2009. 
28. ↑ Markus E. Kasper, et al .: EPICS: the exoplanet imager for the E-ELT . In: SPIE (Ed.): Adaptive Optics Systems - Proceedings of the SPIE, Volume 7015 . 2008, p. 70151S – 70151S-12 , doi : 10.1117 / 12.789047 , bibcode : 2008SPIE.7015E..46K .
29. ↑ Niranjan Thatte: HARMONI . University of Oxford. Retrieved November 30, 2012.
30. ↑ Bernhard Brandl: METIS - The Mid-infrared E-ELT Imager and Spectrograph . METIS consortium. Retrieved November 30, 2012.
31. ^ Bernhard R. Brand et al .: METIS: the mid-infrared E-ELT imager and spectrograph . In: Proceedings of the SPIE . 7014, Aug 2008, pp. 70141N-70141N-15. bibcode : 2008SPIE.7014E..55B . doi : 10.1117 / 12.789241 .
32. ↑ MICADO - Multi-AO Imaging Camera for Deep Observations . MICADO team. Retrieved November 30, 2012.
33. ^ Richard Davies et al .: MICADO: the E-ELT adaptive optics imaging camera . In: Proceedings of the SPIE . 7735, July 2010, pp. 77352A-77352A-12. arxiv : 1005.5009 . bibcode : 2010SPIE.7735E..77D . doi : 10.1117 / 12.856379 .
34. ↑ OPTIMOS EVE: A Fiber-fed Optical Near-infrared multi-object spectrograph for the E-ELT . ESO. Retrieved November 8, 2017.
35. ↑ SIMPLE - A high resolution near-IR spectrograph for the E-ELT . SIMPLE Consortium. Archived from the original on March 4, 2016. Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. Retrieved November 30, 2012. 
36. ↑ E. Oliva, Origlia, L .: High-resolution near-IR spectroscopy: from 4m to 40m class telescopes . In: Proceedings of the SPIE . 7014, Aug 2008, pp. 701410-701410-7. bibcode : 2008SPIE.7014E..56O . doi : 10.1117 / 12.788821 . Retrieved on November 30, 2012.  ( Page no longer available , search in web archives )  Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice.  
37. ↑ EPICS: direct imagine of exoplanets with the E-ELT , accessed September 25, 2017
38. ^ TMT International Observatory: Timeline
39. ↑ Giant Magellan Telescope: Quick Facts