Indian Astronomical Observatory, Hanle

2M Optical Infrared Telescope

the Himalayan Chandra TelescopeFirst light obtained on September 26, 2000
Telescope Released for Science Observations Beginning 2003 May
A 2-m aperture optical-infrared telescope, the Himalayan Chandra Telescope (HCT) manufactured by the EOS Technologies Inc., Tuscon, Arizona, USA is installed at IAO. The telescope is remotely operated from CREST, Hosakote, via a dedicated satellite link.

The telescope is equipped with 3 science instruments which are mounted on an instrument mount cube at the cassegrain focus of the telescope. The instrument mount cube has four side ports and an on-axis port, which makes all three instruments available mounted on the telescope. The instruments currently available are the Himalaya Faint Object Spectrograph (HFOSC), the NIR Imaging Spectrograph (TIRSPEC), and the Hanle Echelle Spectrograph (HESP).

Since May 2014, the NIR imager has been replaced by a new NIR instrument developed by TIFR (TIRSPEC). The details of TIRSPEC are available at

The Hanle Echelle Spectrometer (HESP) is released for observations beginning 2017 January.

  • Instrument Manual
  • Observer's Manual
    • Telescope Specifications
    • Aperture

      2.01 metres

      Mirror Material





      Altitude over azimuth


      Cassegrain; provision for Nasmyth


      f/1.75 primary; f/9 Cassegrain

      Image Scale

      11.5 arcsec/mm

      Field of View

      7 arcmin; 30arcmin with corrector

      Image quality (zenith)

      80% power < 0.33 arcsec dia; 90% power < 0.73 arcsec dia

      Jitter & periodic errors

      < 0.25 arcsec on each axis

      Pointing accuracy

      < 0.45 arcsec over 17 arcsec move;
      < 1.5 arcsec for > 10 deg move

The telescope tracking tests indicate that a tracking accuracy (open loop) of 0.5 arcsec over 10 minutes is met at a good fraction of telescope positions, except at higher elevations, where the tracking worsens, resulting in a mean (over all telescope positions) accuracy of 1.38 arcsec over 10 minutes.

A pointing accuracy of 3 arcseconds has been achieved.

The image quality is estimated to be about 0.7 arcseconds diameter (80% power).

The autoguider (AUGUS) developed at the Copenhagen University Observatory was installed in May 2005. The AUGUS can guide on a 17 mag star in 4 second integration, and uses the HCT Observatory Server interface to close the guiding loop.

Last updated on: February 20, 2024