A 15 cm aperture English-mounted Heliostatic refractor by the French optical firm of Lerebours et Secretan of Paris, acquired in 1850 and remodeled to 20 cm by Grubb-Parsons in 1898 to serve as a 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 cometary and occultation observations and sometimes made available to visitors for night sky viewing.

Twin spectroheliographs giving 6 cm diameter full disc photographs of the sun in K-alpha and H-alpha spectral lines are in regular use.
A 46 cm diameter 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 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 CCD to record the K filtergram.
Regular observations began in 1996.
Besides synoptic observations, temporal sequences are being obtained on days of good to excellent seeing.
A 15 cm aperture English-mounted Heliostatic refractor by the French optical firm of Lerebours et Secretan of Paris, acquired in 1850 and remodeled to 20 cm by Grubb-Parsons in 1898 to serve as a 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 cometary and occultation observations and sometimes made available to visitors for night sky viewing.
Twin spectroheliographs giving 6 cm diameter full disc photographs of the sun in K-alpha and H-alpha spectral lines are in regular use. A 46 cm diameter 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 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 CCD to record the K filtergram. Regular observations began in 1996. Besides synoptic observations, temporal sequences are being obtained on days of good to excellent seeing.
Kodaikanal Solar Observatory