Kodaikanal Solar Observatory - AbsoluteAstronomy.com

The Kodaikanal Solar Observatory is an solar

Sun

The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...

observatory

Observatory

An observatory is a location used for observing terrestrial or celestial events. Astronomy, climatology/meteorology, geology, oceanography and volcanology are examples of disciplines for which observatories have been constructed...

owned and operated by Indian Institute of Astrophysics

Indian Institute of Astrophysics

The Indian Institute of Astrophysics , with its headquarters in Bangalore , India, is a premier national institute of India for the study of and research into topics pertaining to astronomy, astrophysics and related subjects....

. It is located on the southern tip of the Palni Hills

Palni Hills

The Palni Hills are a mountain range in Tamil Nadu state of South India. The Palni Hills are an eastward extension of the Western Ghats ranges, which run parallel to the west coast of India. The Palni Hills adjoin the high Anamalai range on the west, and extend east into the plains of Tamil Nadu,...

4 km from Kodaikanal

Kodaikanal

-Climate:Kodaikanal has a monsoon-influenced subtropical highland climate . The temperatures are cool throughout the year due to the high elevation of the city.-Economy:...

town, Dindigul

Dindigul District

Dindigul District is an administrative region in the south of Tamil Nadu, India. The district was carved out of Madurai District in the year 1985...

district, Tamilnadu state, South India

South India

South India is the area encompassing India's states of Andhra Pradesh, Karnataka, Kerala and Tamil Nadu as well as the union territories of Lakshadweep and Pondicherry, occupying 19.31% of India's area...

.

The Evershed effect

Evershed effect

The Evershed effect, named after the British astronomer John Evershed, is the radial flow of gas across the photospheric surface of the penumbra of sunspots from the inner border with the umbra towards the outer edge....

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

Electrojet

An electrojet is an electric current which travels around the E region of the Earth's ionosphere. There are two electrojets: above the magnetic equator , and near the Northern and Southern Polar Circles . Electrojets are Hall currents carried primarily by electrons at altitudes from 100 to...

are made here due to the unique geographic location of Kodaikanal.

Ionospheric sounding

Ionospheric sounding

In telecommunication and radio science, an ionospheric sounding is a technique that provides real-time data on high-frequency ionospheric-dependent radio propagation, using a basic system consisting of a synchronized transmitter and receiver....

s, geomagnetic, F region

F region

The F region of the ionosphere is home to the F layer of ionization, also called the Appleton layer, after the English physicist Edward Appleton. As with other ionospheric sectors, 'layer' implies a concentration of plasma, while 'region' is the area that contains the said layer...

vertical drift and surface

Meteorology

Meteorology is the interdisciplinary scientific study of the atmosphere. Studies in the field stretch back millennia, though significant progress in meteorology did not occur until the 18th century. The 19th century saw breakthroughs occur after observing networks developed across several countries...

observations are made here regularly and summaries of the data obtained are sent to national IMD

India Meteorological Department

The India Meteorological Department , also referred to as the Met Office, is an agency of the Ministry of Earth Sciences of the Government of India. It is the principal agency responsible for meteorological observations, weather forecasting and seismology...

and global WMO GAW

Gaw

Gaw relatively rare surname amongst those of Scottish, English, and Irish descent, deriving from the Gaelic word meaning "foreigner" .Gaw or GAW can mean:...

data centers.

They have a full time staff of two scientists and nineteen 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".
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

Telescope

A telescope is an instrument that aids in the observation of remote objects by collecting electromagnetic radiation . The first known practical telescopes were invented in the Netherlands at the beginning of the 1600s , using glass lenses...

, which could be located at a hill station in South India.

On July 20, 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. Secretary of State

India Office

The India Office was a British government department created in 1858 to oversee the colonial administration of India, i.e. the modern-day nations of Bangladesh, Burma, India, and Pakistan, as well as territories in South-east and Central Asia, the Middle East, and parts of the east coast of Africa...

, 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

Madras Observatory

The Madras Observatory was founded by the British East India Company in 1786 in Chennai . For over a century it was the only astronomical observatory in India that exclusively worked on the stars. Among the astronomers at the observatory were Norman Robert Pogson, Michael Topping and John Goldingham...

to Kodaikanal and the Observatory was founded on April 1, 1899.

The first observations were commenced at Kodaikanal in 1901. In 1955, ionosonde and geomagnetic facilities were installed at the Kodaikanal Observatory. Between 1922 and 1960 the directors were T. Royds, A. L. Narayan and Amil Kumar Das

Amil Kumar Das

Amil Kumar Das was an Indian astronomer.During the International Geophysical Year, observatories in Madrid, India, and Manila were responsible for monitoring solar effects. The Kodaikanal Solar Observatory in South India performed this monitoring using their recently built solar tunnel telescope....

. In 1960 M. K. Vainu Bappu

Vainu Bappu

Manali Kallat Vainu Bappu was an Indian astronomer and president of the International Astronomical Union. Bappu helped establish several astronomical institutions in India——including the Vainu Bappu Observatory named after him—and also contributed to the establishment of the modern Indian...

became director of the observatory. A 12 m solar tower with modern spectrograph was established in 1960 by A.K. Das and used to perform some of the first ever helioseismology

Helioseismology

Helioseismology is the study of the propagation of wave oscillations, particularly acoustic pressure waves, in the Sun. Unlike seismic waves on Earth, solar waves have practically no shear component . Solar pressure waves are believed to be generated by the turbulence in the convection zone near...

investigations. Measurements of vector magnetic fields were initiated during the 1960s.

In 1977, many of the astronomers from Kodaikanal shifted to Bangalore

Bangalore

Bengaluru , formerly called Bengaluru is the capital of the Indian state of Karnataka. Bangalore is nicknamed the Garden City and was once called a pensioner's paradise. Located on the Deccan Plateau in the south-eastern part of Karnataka, Bangalore is India's third most populous city and...

and established the Indian Institute of Astrophysics

Indian Institute of Astrophysics

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 digitized 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
Temperature
Temperature is a physical property of matter that quantitatively expresses the common notions of hot and cold. Objects of low temperature are cold, while various degrees of higher temperatures are referred to as warm or hot...

, pressure
Pressure
Pressure is the force per unit area applied in a direction perpendicular to the surface of an object. Gauge pressure is the pressure relative to the local atmospheric or ambient pressure.- Definition :...

and rainfall are made here and transmitted to the India Meteorological Department
India Meteorological Department
The India Meteorological Department , also referred to as the Met Office, is an agency of the Ministry of Earth Sciences of the Government of India. It is the principal agency responsible for meteorological observations, weather forecasting and seismology...

and the World Meteorological Organization
World Meteorological Organization
The World Meteorological Organization is an intergovernmental organization with a membership of 189 Member States and Territories. It originated from the International Meteorological Organization , which was founded in 1873...

for use in Weather forecasting
Weather forecasting
Weather forecasting is the application of science and technology to predict the state of the atmosphere for a given location. Human beings have attempted to predict the weather informally for millennia, and formally since the nineteenth century...

and research in the atmospheric sciences
Atmospheric sciences
Atmospheric sciences is an umbrella term for the study of the atmosphere, its processes, the effects other systems have on the atmosphere, and the effects of the atmosphere on these other systems. Meteorology includes atmospheric chemistry and atmospheric physics with a major focus on weather...

.
Public Education about astronomy including public tours of the facility, public access to the astronomy library, public night time telescopic sky viewing, and presentation of speciaized university level courses, seminars and workshops.

Full disc imaging

A 15 cm aperture English mounted Heliostat

Heliostat

A heliostat is a device that includes a mirror, usually a plane mirror, which turns so as to keep reflecting sunlight toward a predetermined target, compensating for the sun's apparent motions in the sky. The target may be a physical object, distant from the heliostat, or a direction in space...

ic refractor by The French optical firm of Lerebour's et Secretan of Paris, acquired in 1850 and remodeled to 20 cm by Grubb-Parson

Sir Howard Grubb, Parsons and Co. Ltd.

Sir Howard Grubb, Parsons and Co. Ltd. was a telescope manufacturer, more commonly known as Grubb Parsons based in Newcastle upon Tyne.-History:...

s in 1898 to serve as a photoheliograph

Sunshine recorders

A sunshine recorder is a device that records the amount of sunshine at a given location. The results provide information about the weather and climate of a geographical area. This information is useful in meteorology, science, agriculture, tourism, and other fields.There are two basic types of...

, has been in use since the early 1900s to obtain 20 cm white light pictures of the Sun on a daily basis, sky permitting. The 20 cm refractor at the Observatory is used occasionally for comet

Comet

A comet is an icy small Solar System body that, when close enough to the Sun, displays a visible coma and sometimes also a tail. These phenomena are both due to the effects of solar radiation and the solar wind upon the nucleus of the comet...

ary and occultation

Occultation

An occultation is an event that occurs when one object is hidden by another object that passes between it and the observer. The word is used in astronomy . It can also refer to any situation wherein an object in the foreground blocks from view an object in the background...

observations and sometimes made available to visitors for night sky viewing.

Twin spectroheliograph

Spectroheliograph

The spectroheliograph is an instrument used in astronomy. It captures a photographic image of the Sun at a single wavelength of light, a monochromatic image...

s giving 6 cm diameter full disc photographs of the Sun in K-alpha

K-alpha

In X-ray spectroscopy, K-alpha emission lines result when an electron transitions to the innermost "K" shell from a 2p orbital of the second or "L" shell...

and H-alpha

H-alpha

H-alpha is a specific red visible spectral line created by hydrogen with a wavelength of 656.28 nm, which occurs when a hydrogen electron falls from its third to second lowest energy level...

spectral line

Spectral line

A spectral line is a dark or bright line in an otherwise uniform and continuous spectrum, resulting from a deficiency or excess of photons in a narrow frequency range, compared with the nearby frequencies.- Types of line spectra :...

s are in regular use. A 46 cm diameter Foucault siderostat feeds light to a 30 cm aperture f/22, Cooke triplet

Cooke triplet

The Cooke triplet is a photographic lens designed and patented in 1893 by Dennis Taylor who was employed as chief engineer by T. Cooke & Sons of York...

lens. The two prism K-alpha spectroheliographs were acquired in 1904 and the H-alpha Diffraction grating

Diffraction grating

In optics, a diffraction grating is an optical component with a periodic structure, which splits and diffracts light into several beams travelling in different directions. The directions of these beams depend on the spacing of the grating and the wavelength of the light so that the grating acts as...

spectroheliograph was operational in 1911. Since 1912, prominent pictures over the full limb are also 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 achromat

Achromatic lens

An achromatic lens or achromat is a lens that is designed to limit the effects of chromatic and spherical aberration. Achromatic lenses are corrected to bring two wavelengths into focus in the same plane....

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 CCD

Charge-coupled device

A charge-coupled device is a device for the movement of electrical charge, usually from within the device to an area where the charge can be manipulated, for example conversion into a digital value. This is achieved by "shifting" the signals between stages within the device one at a time...

to record the K filtergram. Regular observations began in 1996. Besides synoptic

Synoptic

Synoptic is derived from the Greek words σύν and ὄψις , and describes observations that give a broad view of a subject at a particular time. Specific uses include:*Synoptic scale meteorology*Synoptic Gospels*SynOptics...

observations, temporal

Time

Time is a part of the measuring system used to sequence events, to compare the durations of events and the intervals between them, and to quantify rates of change such as the motions of objects....

sequences are being obtained on days of good to excellent seeing.

Solar Tunnel Telescope

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-type spectrograph

Spectrograph

A spectrograph is an instrument that separates an incoming wave into a frequency spectrum. There are several kinds of machines referred to as spectrographs, depending on the precise nature of the waves...

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

Spectroheliograph

The spectroheliograph is an instrument used in astronomy. It captures a photographic image of the Sun at a single wavelength of light, a monochromatic image...

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 ionospheric

Ionosphere

The ionosphere is a part of the upper atmosphere, comprising portions of the mesosphere, thermosphere and exosphere, distinguished because it is ionized by solar radiation. It plays an important part in atmospheric electricity and forms the inner edge of the magnetosphere...

and geomagnetic effects of solar activity. A NBS C3 analogue

Analog signal

An analog or analogue signal is any continuous signal for which the time varying feature of the signal is a representation of some other time varying quantity, i.e., analogous to another time varying signal. It differs from a digital signal in terms of small fluctuations in the signal which are...

ionosonde

Ionosonde

An ionosonde, or chirpsounder, is a special radar for the examination of the ionosphere. An ionosonde consists of:* A high frequency transmitter, automatically tunable over a wide range...

was installed at the Observatory in 1955, for vertical soundings of the ionosphere. Quarterly soundings were made round the clock. In 1993, a digital

Digital

A digital system is a data technology that uses discrete values. By contrast, non-digital systems use a continuous range of values to represent information...

ionosonde model IPS 42/DBD43 was commissioned enabling five minute or better sounding rates.

Other facilities

A high frequency

High frequency

High frequency radio frequencies are between 3 and 30 MHz. Also known as the decameter band or decameter wave as the wavelengths range from one to ten decameters . Frequencies immediately below HF are denoted Medium-frequency , and the next higher frequencies are known as Very high frequency...

Doppler radar

A Doppler radar is a specialized radar that makes use of the Doppler effect to produce velocity data about objects at a distance. It does this by beaming a microwave signal towards a desired target and listening for its reflection, then analyzing how the frequency of the returned signal has been...

was built indigenously and made operational to study F-region Skywave

Skywave

Skywave is the propagation of electromagnetic waves bent back to the Earth's surface by the ionosphere. As a result of skywave propagation, a broadcast signal from a distant AM broadcasting station at night, or from a shortwave radio station can sometimes be heard as clearly as local...

dynamics.

A lacour magnetometer

Magnetometer

A magnetometer is a measuring instrument used to measure the strength or direction of a magnetic field either produced in the laboratory or existing in nature...

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

Museum

A museum is an institution that cares for a collection of artifacts and other objects of scientific, artistic, cultural, or historical importance and makes them available for public viewing through exhibits that may be permanent or temporary. Most large museums are located in major cities...

on campus for the visitors. The displays are mainly pictorial, with a few models, a live solar image and the Fraunhofer

Fraunhofer

Fraunhofer, , may refer to:*Joseph von Fraunhofer , German physicist*Fraunhofer , a lunar crater*Fraunhofer Society , a large German research organization with 59 institutes throughout Germany...

spectrum also presented.

The library

Library

In a traditional sense, a library is a large collection of books, and can refer to the place in which the collection is housed. Today, the term can refer to any collection, including digital sources, resources, and services...

at the Observatory is one of its 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 of the observatory are often used for national and international meetings, workshops and classes for up to 40 participants on related subjects such as: Kodaikanal Summer School in Physics, the Kodai-Trieste workshop on Plasma Astrophysics and the Solar Physics Winter School

Telephone: 04542-240214