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3.6 m DOT

The 3.6m Devasthal Optical Telescope is a custom-built instrument of great complexity. This telescope has the distinction of being largest telescope in India for study of celestial objects at optical wavelengths. It is a national facility installed at Devasthal in the district of Nainital, India. It was commissioned in the year 2016 and is being maintained and operated by ARIES. The 3.6m DOT facility consists of a modern 3.6 meter optical new technology telescope, a suite of instruments, an Aluminium coating plant, a control room and a data center. The back-end instruments of telescope provide spectral and imaging capabilities at visible and near-infrared bands.

Observers/Proposers/Authors are encouraged to mention 3.6m DOT in title or abstract of the research publications and also put an acknowledgement as "Based on observations obtained at the 3.6m Devasthal Optical Telescope (DOT), which is a National Facility run and managed by Aryabhatta Research Institute of Observational Sciences (ARIES), an autonomous Institute under Department of Science and Technology, Government of India.". In addition, It may be required to cite a paper describing instrument set-up etc., as provided in the webpages of the respective instruments.

The observing time on 3.6m Devasthal Optical Telescope is apportioned as follows : 60% open time on competitive basis to any astronomer working in an Indian Institution; 33% guaranteed time for astronomers from ARIES and 7% guaranteed time for Belgian astronomers subject to the scientific merit of the proposals. About 10% of the available science time, will be reserved as Director’s Discretionary Time for allocation by the Director, ARIES.

Observing proposals have to be submitted using the DOT Online Proposal Submission System (DOPSES) at the URL The table below specifies some of the important dates.

Cycle Call for Proposal Deadline for Submission
C1 (February - May) 1st November 1st December
C2 (October - January) 1st July 1st August
Successful proposers will have exclusive access to their scientific data for the duration of a proprietary period. Normally this period will expire one year after the date of observation. Proposers should follow links to the Science observing policy document and the Frequently asked questions for further details.

Proposers requesting time on telescope are advised to browse through the pages of Instruments, Telescope and other sub-menus for Latest Update.


Proposal Deadline : Monday, August 2, 2021, 17:00 IST

ARIES invites proposals from the astronomical community of India and Belgium for observations with 3.6m DOT for the observing cycle from 1st of October 2021 to 31st of January 2022 (DOT-2021-C2). The deadline for receiving these proposals is 1700 hrs Indian Standard Time (UTC+5.5 hrs), 2nd August, 2021. India has 93% share in the telescope time of which 33% is guaranteed to ARIES, and the Belgian share is 7%. The Principal Investigator of the proposals should have affiliations at Indian or Belgian academic institutions and/or universities. The Science observing proposals can be submitted online via the DOT Online proposal management and evaluation system (DOPSES) available at

Notes for proposers of Cycle DOT-2021-C2:

The 3.6m DOT has three cassegrain ports viz. main axial-port, side-port1 and side-port2. It is possible to switch the ports within a minute using a fold mirror. In principle, a set of three instruments can be mounted with the telescope and used near simultaneously. The side-port2 is free at the moment. The 3.6m DOT currently offers four instruments (IMAGER, TIRCAM2, ADFOSC, TANSPEC) for carrying out high resolution imaging and low resolution spectroscopic observations of celestial sources. The TIRCAM2 is permanently mounted on the side-port1 of the telescope and it is always available for observations, whereas other instruments are mounted one at a time on the axial-port.
  Instrument sequence for cycle DOT-2021-C2 : Tentatively, IMAGER shall be available during October, TANSPEC during October to December, then IMAGER in December and ADFOSC during December 2021 to January 2022. The final sequence as well as the precise dates may be derived from the demand for instruments by proposers.
  Proposers requesting time on telescope via DOPSES are advised to browse through the pages of Instruments and Telescope for Latest Update on current sensitivities and upgrade.