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104cm Sampurnanand Telescope

The 104-cm Sampurnanand Telescope, located at ARIES, Manora Peak, Nainital, is one of the the main observing facility in optical domain. It was installed in 1972 by Carl Zeiss, Germany.

104 cm telescope.

The telescope is an RC reflector with a Cassegrain focus and mounted on equatorial 2-pier english mount.  The 104-cm, f/13 telescope produce a field of around 45 arcmin with corrector at the cassegrain end. The tracking accuracy is around 7 arcsec/hr (0.1 arcsec/min) without guider and is around 0.7 arcsec/hr with guider.  Three finder telescopes are also provided with clear aperture of around 10-inch (264 mm, f/14, reflector), 8-inch (200 mm, f/15, refractor) and 4-inch (110 mm, f/7, refractor type). The 8 and 4-inch finder telescopes are equipped with eyepieces which covers around 20 and 90 arcmin field of view respectively. The 8-inch refractor is generally using for guiding the main telescope using ST4 camera.

Milkyway over 104 cm telescope dome at night.

Different  scientific programs such as;  study of star-clusters, young star-forming regions, HII regions, AGN and brown dwarfs, optical counterpart of Gamma-ray-bursts(GRBs), supernovae and X-ray sources, polarimetric studies of open clusters, star-forming regions and late type stars were carried out with this observing facility.  So far, the total research output of the 104cm Sampurnanand Telescope  reaches nearly 364 scientific publications in different refereed journals  and 45 PhD Thesis.


Tek 1kx1k  CCD:  Tek 1024 x 1024 is a grade 1 CCD with 24 micron pixel size. This camera was acquired In 1992 and is being used for photometric observation. The detector covers an area of around 6 x 6 arcmin in the sky. It works in non-MPP mode with dark current equal 0.56 e−/sec/pix at -110 deg C. Full well capacity is 390 ke-. It can work at three gain (1X, 2X, 4X) settings viz gain = 11.98 e−/ADU, read out noise are 7.0, 5.0 and 4.1 electrons. It is a slow 40 kHz system with 15-bit A/D converter.

1340 x 1300 PyLON CCD:  PyLoN 1340 x 1300 CCD is a scientific grade CCD with pixel size of 20 micron. It was acquired in 2016. This CCD is work in MPP mode with dark current .3 electron/pix/hour. It covers an 6.8 x 6.5 arcmin field of view in the sky and operating at temperature -120 degree C. The CCD reads out its pixels with a speed of  50 kHz to 5 MHz  and the corresponding gain are 1, 2, 4, 8, 16 e−/ADU with 16-bit A/D converter.

ARIES Imaging Polarimeter (AIMPOL): The AIMPOL has recently been developed and is in use since 2004. This instrument measures linear polarisation in UBVRI bands and has a field of view of around 8 arcmin. Using 104 cm telescope, it can measure polarisation of a 13 magnitude star in 2 minute exposure time with 0.18 percent accuracy. This Polarimeter uses Tek-1k x 1k ccd (described above) as detector.                                

  1. The first photoelectric observations of stars from Indian soil were obtained at the institute.
  2. In the country, first successful photoelectric observations of occultation of a star by a minor planet were taken at the institute.
  3. The institute contributed to the detection of rings around Uranus by observing the occultation of a star by Uranus.
  4. Two additional rings around Saturn were detected, out of these one ring was detected for the first time.
  5. The ring around Neptune were discovered independently.
  6. Based on observed data on galactic clusters, it has been found that the plane defined by the interstellar dust is tilted with respect to the formal galactic plane.
  7. A large number of eclipsing binaries, variable stars and galactic clusters has been observed and many new results have been published. The cluster study indicates that slope of the initial mass function above one solar mass is universal and similar to Salpeter’s value.
  8. As a result of optical tracking of artificial satellites, the location of Manora Peak has been determined with a precision of 10 meters in the frame of reference of Standard earth. This information is valuable for a geological survey.
  9. A large number of comets including Comet Halley have also been observed.
  10. Optical observations of the  afterglows of Gamma ray Bursts have been taken including the first one observed from the country.
  11. It was shown for the first time that intra-night optical variability with amplitude >3% is associated exclusively with (blazer) jet streams high optical polarization. This establishes a direct link between relativistic beaming and optical micro-variability. The AGN classes showing low optical polarization(< 3%) exhibit very low level optical intra night variability.
  12. The milli-magnitude variability in few chemically peculiar stars have been discovered. Detection of such small amplitude photometric variability indicate the excellent photometric sky conditions at Manora Peak, Nainital.