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{{Use dmy dates|date=August 2018}}
{{Use Indian English|date=August 2018}}
{{Infobox Observatory
|name = Kodaikanal Solar Observatory
|background =
|image = [[File:Kodaikanal Solar Observatory-a.jpg|250px]]
|caption = Kodaikanal Solar Observatory
|organization = [[Indian Institute of Astrophysics]]
|code =
|location = [[Kodaikanal]], [[India]]
|coords = {{coord|10|13|56|N|77|27|53|E|}}
|altitude = 2,343 meters (7,687 ft)
|Telephone = 04542-240245
|established =
|closed =
|website = http://www.iiap.res.in/centers/kodai
|telescope1_name = [[Coelostat]]
|telescope1_type = 60 cm reflector - KSO Tunnel Telescope
|telescope2_name = [[Sir Howard Grubb, Parsons and Co. Ltd.|Grubb-Parson]]s
|telescope2_type = 20 inch refractor Bavanagar Telescope
|telescope3_name = WARM [White Light Active Region Monitoring]Telescope
|telescope3_type = H-alpha Telescope
|telescope4_name = TWIN Telescope
|telescope4_type = SPECTRO - Telescope
}}

The '''Kodaikanal Solar Observatory''' is a [[Sun|solar]] [[observatory]] owned and operated by the [[Indian Institute of Astrophysics]]. It is on the southern tip of the [[Palani Hills]] 4 km from [[Kodaikanal]] town, [[Dindigul District|Dindigul district]], [[Tamil Nadu]] state, [[South India]].

The [[Evershed effect]] was first detected at this observatory in January 1909. Solar data collected by the lab is the oldest continuous series of its kind in India. Precise observations of the equatorial [[electrojet]] are made here due to the unique geography of Kodaikanal.

[[Ionospheric sounding]]s, [[geomagnetic]], [[F region]] vertical drift and [[Meteorology|surface]] observations are made here regularly. Summaries of the data obtained are sent to national ([[India Meteorological Department]]) and global ([[World Meteorological Organization]], [[Global Atmosphere Watch]]) data centers.<ref>Global Atmosphere Watch, Swiss Federal Laboratories for Materials Testing and Research (EMPA), Dübendorf, Switzerland.
[http://www.empa.ch/gaw/gawsis/reports.asp?StationID=230 Station Characteristics, Kodaikanal] {{webarchive|url=https://web.archive.org/web/20070928003623/http://www.empa.ch/gaw/gawsis/reports.asp?StationID=230 |date=2007-09-28 }}</ref>

They have a full-time staff of two scientists and three technicians.

==History==
As early as 1881, Mr. Blanford, then Meteorological Reporter to the government of India, recommended "the improvement of the work of solar observations in order to obtain accurate measures of the sun’s heating power at the earth’s surface and its periodic variations".<ref>[http://docs.lib.noaa.gov/rescue/mwr/034/mwr-034-05-0220a.pdf MONTHLY WEATHER REVIEW. MAY, 1906]</ref>
In May 1882, the government astronomer at Madras, [[Norman Robert Pogson]], proposed the need for photography and [[spectrography]] of the sun and the stars using a twenty-inch [[telescope]], which could be at a hill station in South India.

On 20 July 1893 following a famine in Madras Presidency, which underscored the need for a study of the sun to better understand monsoon patterns, a meeting of the [[U.K.]] [[India Office|Secretary of State]], Indian Observatories Committee, chaired by [[Lord Kelvin]], decided to establish a solar physics observatory at Kodaikanal, based on its southern, dust free, high altitude location. Michie Smith was selected to be superintendent. Starting in 1895 there was a rapid transfer of work and equipment from the [[Madras Observatory]] to Kodaikanal and the observatory was founded on 1 April 1899.

The first observations were commenced at Kodaikanal in 1901.<ref>Indian Institute of Astrophysics - A Brief History, Solar Observatory at Kodaikanal, retrieved 3/13/2007.[http://www.iiap.res.in/centers/kodai]</ref>

Partial List of Assistant Directors
* [[John Evershed]]<ref name="obit_evershed_mnras">{{cite journal
| last = Stratton
| first = F. J. M.
| author-link = F. J. M. Stratton
| title = John Evershed
| journal = [[Monthly Notices of the Royal Astronomical Society]]
| volume = 117
| number = 3
| pages = 253–254
| publisher = [[Royal Astronomical Society]]
| date = 1957
| bibcode = 1957MNRAS.117..253.
| url = http://articles.adsabs.harvard.edu/full/1957MNRAS.117..253.
| accessdate = 17 February 2017
|doi = 10.1093/mnras/117.3.253 | doi-access = free}}</ref> 1906–1911
* [[Thomas Royds]]<ref name="obit_royds_mnras">{{cite journal
| last = Stratton
| first = F. J. M.
| author-link = F. J. M. Stratton
| title = Thomas Royds
| journal = [[Monthly Notices of the Royal Astronomical Society]]
| volume = 116
| number = 2
| pages = 156–158
| publisher = [[Royal Astronomical Society]]
| date = 1956
| bibcode = 1956MNRAS.116..156.
| url = http://articles.adsabs.harvard.edu/full/1956MNRAS.116..156.
| accessdate = 17 February 2017
|doi = 10.1093/mnras/116.2.156 | doi-access = free}}</ref> 1911–1923
* [[Anil Kumar Das]]<ref name="obit_das_mnras">{{cite journal
| last = Bappu
| first = M. K. V.
| author-link = Vainu Bappu
| title = Anil Kumar Das
| journal = [[Quarterly Journal of the Royal Astronomical Society]]
| volume = 2
| number = 4
| pages = 278–279
| publisher = [[Royal Astronomical Society]]
| date = 1961
| bibcode = 1961QJRAS...2..278.
| url = http://articles.adsabs.harvard.edu/full/1961QJRAS...2..278.
| accessdate = 17 February 2017
}}</ref> 1937–1946

List of Directors
* Charles Michie Smith<ref name="rao_vagiswari_birdie">{{cite journal
| title= Charles Michie Smith – founder of the Kodaikanal (Solar Physics) Observatory and beginnings of physical astronomy in India
| last = Rao | first = N. K.
| last2 = Vagiswari | first2 = A.
| last3 = Birdie | first3 = C.
| journal = [[Current Science]]
| volume = 106
| number = 3
| pages = 447–467
| url = http://www.currentscience.ac.in/Volumes/106/03/0447.pdf
| date = 2014
| arxiv = 1402.6189
|bibcode = 2014arXiv1402.6189K }}</ref><ref name="obit_michiesmith_mnras">{{cite journal
| title = Professor Charles Michie Smith
| journal = [[Monthly Notices of the Royal Astronomical Society]]
| volume = 83
| number = 4
| pages = 245–246
| publisher = [[Royal Astronomical Society]]
| date = 1923
| bibcode = 1923MNRAS..83R.245.
| url = http://articles.adsabs.harvard.edu/full/1923MNRAS..83R.245.
| accessdate = 17 February 2017
| doi=10.1093/mnras/83.4.245a
| doi-access = free
}}</ref> [[FRSE]] 1895–1911
* [[John Evershed]] 1911–1923
* [[Thomas Royds]] 1923–1937
* A. L. Narayan 1937–1946
* [[Anil Kumar Das]] 1946–1960
* [[Vainu Bappu|M. K. Vainu Bappu]] 1960–1982
*[[J.C.Bhattacharya]] 1982-1990
*[[Ramnath Cowsik]] 1992 - 2003
*[[S.Siraj Hasan]] 2006 - 2012
*[[P.Sreekumar]] 2013 - 2018
*[[Jayant Murthy]] 2018–Present

A 12 m solar tower with modern spectrograph was established in 1960 by [[Amil Kumar Das]] and used to perform some of the first ever [[helioseismology]] investigations. Measurements of vector [[Magnetic field of celestial bodies|magnetic fields]] were initiated during the 1960s.

In 1977, many of the astronomers from Kodaikanal shifted to [[Bangalore]] and established the [[Indian Institute of Astrophysics]].<ref>Swarup Govind, "Historical perspective and research centres in India in the fields of solar astronomy and Sun-Earth relationship," National Centre for Radio Astrophysics, TIFR, Pune 411007, India. retrieved 3/13/2007 [http://cdaw.gsfc.nasa.gov/publications/ilws_goa2006/00011_Inaugural_Swarup.pdf]</ref>

==Current activities==
Areas of current interest at the observatory are
*Observations and interpretation of the morphological changes in active regions and their role in occurrence of transients such as [[solar flares]].
*Study of contributing factors to chromospheric calcium K indices.
*Measurement of vector magnetic fields.
*Photographs of ~ 100 years are being [[digitize]]d for long term studies of the last ten solar cycles.
*Studies on the structure and dynamics of equatorial ionosphere and its response to the solar and interplanetary variability are being carried out.
*Studies of the equatorial electrojet and of the structure and dynamics of equatorial ionosphere and its response to solar and interplanetary variability are being made.
*Hourly observation of surface [[temperature]], [[pressure]] and [[rainfall]] are made here and transmitted to the [[India Meteorological Department]] and the [[World Meteorological Organization]] for use in [[Weather forecasting]] and research in the [[atmospheric sciences]].
*Public education about astronomy including tours of the facility, access to the astronomy library, night time telescopic sky viewing, and presentation of specialized university level courses, seminars and workshops.

==Equipment==

===Full disc imaging===
[[File:Solar eclips 1999 5.jpg|thumb|250px|[[Chromosphere]] of the [[Sun]] showing the red [[H-alpha]] [[spectral line]] observed during an [[eclipse]].]]
A 15 cm aperture English-mounted [[Heliostat]]ic [[refractor]] by the French [[optical]] firm of [[Noël Marie Paymal Lerebours|Lerebours et Secretan]] of Paris, acquired in 1850 and remodeled to 20 cm by [[Sir Howard Grubb, Parsons and Co. Ltd.|Grubb-Parson]]s in 1898 to serve as a [[Sunshine recorders|photoheliograph]], has been in use since the early 1900s to obtain daily 20 cm white light pictures of the sun, sky permitting. The 20 cm refractor is used occasionally for [[comet]]ary and [[occultation]] observations and sometimes made available to visitors for night sky viewing.

Twin [[spectroheliograph]]s giving 6 cm diameter full disc photographs of the sun in [[K-alpha]] and [[H-alpha]] [[spectral line]]s are in regular use. A 46 cm diameter [[Léon Foucault#Middle years|Foucault]] [[siderostat]] feeds light to a 30 cm aperture f/22, [[Cooke triplet]] lens. The two prism K-alpha spectroheliographs were acquired in 1904 and the H-alpha [[diffraction grating]] spectroheliograph was operational in 1911. Since 1912, prominent pictures over the full limb are being obtained in K by blocking the solar disc. These observations and the white light pictures are obtained around 200 days a year.

Light from the 46 cm siderostat is diverted to a 15 cm Zeiss [[Achromatic lens|achromat]] objective which provides an f/15 beam and a 2 cm image. A prefilter and a daystar Ca K narrow band filter are used together with a Photometrix 1k x 1k [[Charge-coupled device|CCD]] to record the K filtergram.<ref>Darling David, ''The Encyclopedia of Astrobiology, Astronomy, and Spaceflight'', filtergram, retrieved 3/13/2007.</ref> Regular observations began in 1996. Besides [[synoptic scale astronomy|synoptic]] observations, [[Time|temporal]] sequences are being obtained on days of good to excellent seeing.

===Solar tunnel telescope===
[[File:Kodaikanal Solar Observatory-b.jpg|thumb|250px|Solar Tunnel Telescope at Kodaikanal]]
A [[Grubb Parson]] 60 cm diameter two-mirror fused quartz [[coelostat]] mounted on 11 m tower platform directs sunlight via a flat mirror into a 60 m long underground horizontal 'tunnel'. A 38 cm aperture f/90 achromat forms a 34 cm diameter solar image at the focal plane. The telescope has an option to mount a 20 cm achromat, which provides an f/90 beam to form a 17 cm image.

A [[Littrow prism|Littrow]]-type [[spectrograph]] is the main instrument of the telescope. A 20 cm diameter, 18 m focal length [[achromat]] in conjunction with a 600 lines/mm grating gives 9 mm/A dispersion in the fifth order of the grating. Together with the 5.5 arcsec/mm spatial resolution of the image, it forms a high resolution set up for solar spectroscopy. Recording of the spectrum can be done photographically or with a Photometrix 1k x 1k CCD system. A large format CCD system is being procured to enhance the coverage of spectrum especially for the broad resonance lines and the nearby continuum.

The converging solar beam from the objective can be diverted to a high dispersion [[spectroheliograph]] with Littrow arrangement using a 3.43 m achromat. The photographic camera behind the second slit is being replaced by a Raticon linear array and a data acquisition system.

===Ionosondes===
The lab is equipped for studying the [[ionosphere|ionospheric]] and geomagnetic effects of solar activity. A NBS C3 [[analog signal|analogue]] [[ionosonde]] was installed in 1955, for vertical soundings of the ionosphere. Quarterly soundings were made round the clock. In 1993, a [[Digital data|digital]] ionosonde model IPS 42/DBD43 was commissioned enabling five minute or better sounding rates.

===Other facilities===
A [[high frequency]] [[Doppler radar]] was built indigenously and made operational to study F-region [[Skywave]] dynamics.

A lacour [[magnetometer]] and a Watson magnetometer were installed and have been used regularly at the observatory since the early 1900s.

They also have a broadband [[seismograph]], [[GPS]] receiver and magnetic variometers.

The observatory has a popular astronomy [[museum]] on campus for the visitors. The displays are mainly pictorial, with a few models, a live solar image and the [[Fraunhofer line|Fraunhofer]] spectrum also presented.

The [[library]] is one of the observatory's proud possessions. It has a collection of astronomical literature, which is of archival value. The library maintains a skeletal collection of current literature in solar and solar terrestrial physics.

The modern meeting and accommodation facilities are often used for national and international meetings, workshops and classes for up to 40 participants on subjects such as Kodaikanal Summer School in Physics, the Kodai-Trieste Workshop on Plasma Astrophysics<ref>[http://www.iiap.res.in/ ''Kodai-Trieste workshop on Plasma Astrophysics'' retrieved 3/13/2007] {{webarchive|url=https://web.archive.org/web/20120625111442/http://www.iiap.res.in/ |date=2012-06-25 }}</ref> and the Solar Physics Winter School.<ref>Indian Institute of Astrophysics, 2006 ''Solar Physics Winter School'', retrieved 3/13/2007.[http://www.iiap.res.in/kodsch/]</ref>

==See also==
*[[Kavasji Naegamvala]]
*[[List of astronomical observatories]]

==References==
{{Reflist}}

==External links==
{{Commons category}}
*[http://www.iiap.res.in/centers/kodai Indian Institute of Astrophysics, Kodaikanal Observatory]
*[https://web.archive.org/web/20120717181636/http://www.frontlineonnet.com/fl1613/16130880.htm SUBRAMANIAN T.S. (1999) the Hindu, Volume 16-Issue 13, June 19. "''Centenary of a solar observatory''"], retrieved 3/13/2007
*[http://www.ias.ac.in/resonance/Aug2002/pdf/Aug2002p16-28.pdf Madras and Kodaikanal Observatories : A Brief History]
*[http://janus.lib.cam.ac.uk/db/node.xsp?id=CV%2FCorp%2FKodaikanal%20Observatory Cambridge University Library: Royal Greenwich Observatory Archives, Kodaikanal Solar Observatory, archive papers 1892-1963], retrieved 3/13/2007.
*Further reading: Antia H. M., Bhatnagar A., Ulmschneider P. (ed.s) (2006) ''Lectures on Solar Physics (Lecture Notes in Physics)'', Cambridge University Press, New York, 335 pages [https://www.amazon.com/gp/reader/3540015280/ Excerpts], retrieved 3/13/2007

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Kodaikanal Solar Observatory - Revision history

imported>JoeNMLC at 14:12, 12 August 2021