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 near-IR imager, and the optical CCD imager.

The NIR instrument is replaced by a new NIR instrument developed by TIFR (TIRSPEC). The details of TIRSPEC are available at

  • 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

  • Current Performance
  • 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 28.02.2014