Editing Swedish Solar Telescope

{{Short description|Telescope on La Plama, Canary Islands}}
{{Infobox telescope|locmapin=Canary Islands}}
The '''Swedish 1-m Solar Telescope'''<ref>{{cite journal
|last=Scharmer
|first=Göran
|author2=Owner-Petersen, M. |author3=Korhonen, T. |author4= Title, A. 
|title=The New Swedish Solar Telescope
|journal=High Resolution Solar Physics: Theory, Observations, and Techniques
|date=1999
|volume=183
|series=Astronomical Society of the Pacific Conference series
|editor=T. R. Rimmele
|editor2=K. S. Balasubramaniam
|editor3=R. R. Radick
|pages=157–168
|bibcode=1999ASPC..183..157S}}</ref><ref>{{cite journal
|title=The 1-meter Swedish solar telescope
|journal=Proceedings of the SPIE
|last=Scharmer
|first=Göran
|date=February 2003
|volume=4853
|series=Innovative Telescopes and Instrumentation for Solar Astrophysics.
|pages=341–350
|doi=10.1117/12.460377
|author2=Bjelksjö, Klas |author3=Korhonen, Tapio K. |author4=Lindberg, Bo |author5= Petterson, Bertil 
|url=http://dubshen.astro.su.se/wiki/images/4/4c/Scharmer03meter.pdf
|bibcode=2003SPIE.4853..341S
}}</ref><ref>{{cite web
|title=Swedish 1-meter Solar Telescope
|url=http://dubshen.astro.su.se/wiki/index.php/Swedish_1-meter_Solar_Telescope
|work=SST Wiki
|publisher=Institute for Solar Physics
|accessdate=28 May 2011}}</ref> (or SST) is a refracting [[solar telescope]] at [[Roque de los Muchachos Observatory]], [[La Palma]] in the [[Canary Islands]]. It is run by the [[Institute for Solar Physics]] of [[Stockholm University]]. The primary element is a single [[Fused quartz|fused silica]] lens, making it the [[List of largest optical refracting telescopes|largest optical refracting telescope]] in use in the world. The [[Swedish Solar Telescope|Swedish 1-m Solar Telescope]], with a lens diameter of 43 inches, is technically larger than Yerkes Observatory, only 39 inches are clear for the aperture. The SST is most often used as a [[Ludwig_Schupmann|Schupmann telescope]], thereby correcting the [[chromatic aberration]]s of the singlet primary.

The SST is a vacuum telescope, meaning that it is evacuated internally to avoid disruption of the image from air inside. This is a particular problem with solar telescopes because of the heating from the large amounts of light collected being passed on to any air causing image degradation.

As of 2005 the SST has produced the highest resolution images on the Sun of any telescope. This is largely thanks to its [[adaptive optics]] system,<ref>{{cite journal
|title=Adaptive optics system for the new Swedish solar telescope
|journal=Proceedings of the SPIE
|date=February 2003
|volume=4853
|series=Innovative Telescopes and Instrumentation for Solar Astrophysics
|pages=370–380
|url=http://dubshen.astro.su.se/wiki/images/8/8d/Scharmer03adaptive.pdf
|author=Scharmer, Göran B.
|author2=Dettori, Peter M.
|author3=Löfdahl, Mats G.
|author4=Shand, Mark
|doi=10.1117/12.460387
|bibcode=2003SPIE.4853..370S
|citeseerx=10.1.1.20.357
}}</ref> which was upgraded to an 85-electrode monomorph [[deformable mirror]] from CILAS<ref>
{{cite journal
|title=Recent results and future DMs for astronomy and for space applications at CILAS
|journal=Proceedings of the SPIE
|date=2014
|volume=9148
|series=Adaptive Optics Systems IV
|pages=91480G
|author=Sinquin, Jean-Christophe
|author2=Bastard, Arnaud
|author3=Beaufort, Emmanuel
|author4=Berkefeld, Thomas
|author5=Cadiergues, Laurent
|author6=Costes, Vincent
|author7=Cousty, Raphaël.
|author8=Dekhtiar, Charles
|author9=Di Gesu, Frédéric
|author10=Gilbert, Xavier
|author11=Grèzes-Besset, Catherine
|author12=Groeninck, Denis
|author13=Hartung, Markus
|author14=Krol, Hélène
|author15=Moreau, Aurélien
|author16=Morin, Pierre
|author17=Pagès, Hubert
|author18=Palomo, Richard
|author19=Scharmer, Göran
|author20=Soltau, Dirk
|author21=Véran, Jean-Pierre
|doi=10.1117/12.2056287
|bibcode=2014SPIE.9148E..0GS
}}</ref> in 2013.

There are two modes of operation, selected by switching the beam from one optical table to another. One mode is a spectrograph mode, using the [[#TRIPPEL|TRIPPEL]] spectrograph. The other mode is an imaging mode, where the beam is split up in a red and a blue part by a 500-nm dichroic beamsplitter. Both beams have dual [[Fabry–Pérot interferometer|Fabry-Pérot]]-based tunable filters,<ref>{{cite journal|last=Scharmer|first=G. B.|title=Comments on the optimization of high resolution Fabry-Pérot filtergraphs|journal=Astronomy and Astrophysics|date=March 2006|volume=447|issue=3|pages=1111–1120|doi=10.1051/0004-6361:20052981|url=http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2006A%26A...447.1111S&link_type=ARTICLE&db_key=AST&high=|accessdate=28 May 2011|bibcode=2006A&A...447.1111S|doi-access=free}}</ref> [[#CRISP|CRISP]] in the red and [[#CHROMIS|CHROMIS]] in the blue. The image data are usually compensated for residual wavefront aberrations by use of the MOMFBD image reconstruction method.<ref>{{cite journal
|author=van Noort, Michiel
|author2=Rouppe van der Voort, Luc
|author3=Löfdahl, Mats G.
|title=Solar Image Restoration By Use Of Multi-frame Blind De-convolution With Multiple Objects And Phase Diversity
|journal=Solar Physics
|date=2005
|volume=228
|issue=1–2
|pages=191–215
|doi=10.1007/s11207-005-5782-z
|bibcode=2005SoPh..228..191V
}}</ref><ref>{{cite journal
|author=Löfdahl, Mats G.
|title=Multi-frame blind deconvolution with linear equality constraints
|journal=SPIE Proceedings
|date=2002
|volume=4792
|editor=Bones, Philip J. 
|editor2=Fiddy, Michael A. 
|editor3=Millane, Rick P.|editor-link3=Rick Millane 
|pages=146–155 
|doi=10.1117/12.451791
|arxiv=physics/0209004
|bibcode=2002SPIE.4792..146L
|series=Image Reconstruction from Incomplete Data II
}}</ref>

The SST superseded the SVST<ref>
{{cite journal
|last=Scharmer
|first=Göran B.
|author2=Brown, David S. |author3=Pettersson, Lennart |author4=Rehn, John 
|title=Concepts for the Swedish 50-cm vacuum solar telescope
|journal=Applied Optics
|date=1985
|volume=24
|issue=16
|pages=2558–2564
|doi=10.1364/AO.24.002558
|url=http://www.opticsinfobase.org/abstract.cfm?&id=61636
|bibcode = 1985ApOpt..24.2558S |url-access=subscription
}}</ref> – the [[Swedish Vacuum Solar Telescope]] – which was 47,5&nbsp;cm in diameter.

==Instruments==

===CHROMIS===

The ''CHROMospheric Imaging Spectrometer''<ref>{{cite web|title=CHROMIS|url=https://dubshen.astro.su.se/wiki/index.php/CHROMIS|work=SST wiki|publisher=Institute for Solar Physics|accessdate=26 September 2017}}</ref> (CHROMIS) was installed in 2016. It is similar to [[#CRISP|CRISP]] (but so far without polarimetry) and designed for use at wavelengths in the range 380–500&nbsp;nm. In particular, CHROMIS is optimized for use in the Ca&nbsp;II H and K lines, which are formed in the upper chromosphere. The total system uses three 1920×1200-pixel Grasshopper 3 CMOS cameras from Point Grey (now FLIR). One camera is used for direct narrow-band observations and two, in a phase-diversity configuration, are collecting simultaneous wide-band image data.

===CRISP===

The ''CRisp Imaging SpectroPolarimeter''<ref>{{cite web|title=SST CRISP images|url=http://www.isf.astro.su.se/crisp.html|work=SST website|publisher=Institute for Solar Physics|accessdate=28 May 2011}}</ref><ref>{{cite journal
|last=Scharmer|first=G. B.
|author2=Narayan, G.
|author3=Hillberg, T.
|author4=de la Cruz Rodriguez, J.
|author5=Löfdahl, M. G.
|author6=Kiselman, D.
|author7=Sütterlin, P.
|author8=van Noort, M.
|author9=Lagg, A.
|title=CRISP Spectropolarimetric Imaging of Penumbral Fine Structure|journal=The Astrophysical Journal|date=December 2008|volume=689|issue=1|pages=L69–L72|doi=10.1086/595744|arxiv=0806.1638|bibcode=2008ApJ...689L..69S}}</ref><ref>{{cite web|title=CRISP|url=https://dubshen.astro.su.se/wiki/index.php/CRISP|work=SST wiki|publisher=Institute for Solar Physics|accessdate=26 September 2017}}</ref> (CRISP) was installed in 2008. It operates from 510 to 860&nbsp;nm and is able to measure polarization by using liquid crystal modulation combined with a polarizing beam splitter. The total system uses three 1k × 1k Sarnoff CCDs, two are used for direct narrow-band observations and the third is collecting simultaneous wide-band images.

===TRIPPEL===

The ''TRI-Port Polarimetric Echelle-Littrow''<ref>{{cite web|title=TRIPPEL spectrograph|url=http://dubshen.astro.su.se/wiki/index.php/Spectrograph|work=SST Wiki|publisher=Institute for Solar Physics|accessdate=28 May 2011}}</ref>  (TRIPPEL) is a [[Littrow spectrograph]] using a 79 grooves/mm [[echelle grating]] with a blaze angle of 63.43 degrees. TRIPPEL's wavelength range is about 380–1100&nbsp;nm, and it has a moderate resolution for a solar telescope, with R being approximately 200,000. This corresponds to about 1.3&nbsp;km/s on the solar surface.

TRIPPEL has a number of key useful features. It allows simultaneous observations at 3 different wavelengths, can in principle exploit the full spatial resolution of the SST, and has good polarimetric properties.

==See also==
[[File:Sunrise at the Swedish Solar Telescope.jpg|240px|thumb|Sunrise at the telescope.]]
* [[List of solar telescopes]]
* [[Dutch Open Telescope]]

== References ==
{{reflist}}

== External links ==
* [http://www.isf.astro.su.se/NatureNov2002/telescope_eng.html Information on the SST] from the Institute for Solar Physics
* [http://dubshen.astro.su.se/wiki/index.php/Swedish_1-meter_Solar_Telescope Information on the SST] at the Institute for Solar Physics wiki
* SST [[APOD]] pictures of a [http://apod.nasa.gov/apod/ap021114.html sunspot], the [http://apod.nasa.gov/apod/ap040610.html Venus transit], [http://apod.nasa.gov/apod/ap081102.html spicules on the solar surface], and [http://apod.nasa.gov/apod/ap100416.html bright points] in the solar granulation.
* [[APOD]] picture of the [http://apod.nasa.gov/apod/ap020819.html Roque de los Muchachos Observatory]. The SST is the third from the right.

{{Commons category|Swedish Solar Telescope}}

[[Category:Astronomical observatories in La Palma]]
[[Category:Solar telescopes]]