The Vainu Bappu Observatory


The Largest Telescope in Asia with a diameter of 2.3M

Ever since its commissioning in 1986 the 2.3 m aperture Vainu Bappu Telescope has been operated as a National Facility.

    Technical Details

    Primary Mirror Diameter: 234cm

    Prime focus: f/3.25 with a scale of 27".1/mm

    Cassegrain focus: f/13 with a scale of 6".8/mm

    Guiding: remote, manual guiding


  • At PRIME focus:
  • High-Resolution Echelle Spectrograph :

    The 2.3m telescope is equipped with the fibrefed coude echelle spectrometer.Spectrometer operates in a littrow mode and consists of a six-element collimator-camera system which operates both as a collimator to the input and as a camera to the dispersed output beam. The main dispersing element is a spectrometer that consists of a 408 X 204 mm^2 echelle grating of 52.6 gr/mm with a blaze angle of 70 degree. The input beam size is 150 mm. The dispersed spectrum is recorded on 2k X 4K, 15 micron pixel CCD (read out time is approx 6 min) or a 1K X 1K 24-micron CCD camera with read-out time is around 30 seconds. The star light is fed to the spectrometer from the prime focus of the telescope by an optical fibre. Spectra of resolution R = ~30,000 - 100,000 can be obtained by varying the slit width. Details about the spectrograph are available in Rao et al. 2005, JAPA, 26, 331.

    Imaging Camera with a 3-element Wynne corrector

    The Prime Focus Imaging Camera is equipped with a 1K X 1K 24-micron CCD camera, with a gain of 5.9 e/ADU and readout noise of 8-9 e. The FOV is 10 X 10 arcmin with a scale of ~ 0.6 arcsec/pixel.

  • At CASSEGRAIN focus:
  • Medium resolution Optometrics Research Spectrograph (OMRS)

Last updated on: November 20, 2020