Aryabhatta Research Institute
of observational Sciences
3.6m Devasthal Optical Telescope (DOT)
Aryabhatta Research Institute
of observational Sciences
The 3.6m DOT building under the stars. (Credits: Sarath Prabhav).
The 3.6-meter Devasthal Optical Telescope (DOT) is a cutting-edge telescope maintained and operated by ARIES as a national facility. This telescope is located at Devasthal, in the Nainital district of Uttarakhand. It was developed by Advanced Mechanical and Optical Systems (AMOS, Belgium) in collaboration with other international partners. The technical activation of the DOT took place in 2016, jointly by the Honorable Prime Ministers of India and Belgium. The 3.6m DOT facility comprises a modern 3.6-meter optical new-technology telescope, a suite of instruments for both imaging and spectroscopy covering the optical to near-infrared regions of the electromagnetic spectrum, an aluminum coating plant, a control room, and a data center.
Users can explore different pages using the navigation buttons at the top of this page. To return to the ARIES homepage, simply click on the ARIES logo. Important information for observers will be posted on the current page. Scroll down to find details about observation cycles, the allocation of observation time across different categories, and information on both current and past observation cycles. Key documents for observers, along with details about DOT data credits, are available at the bottom of this page. For information on telescope and site specifications and related documents, click on the Telescope and site button. Details about backend instruments can be found on the Instruments page, which includes pictorial navigation buttons for each instrument. Observation proposals can be submitted through the Proposal submission button. Up-to-date weather information, including the all-sky camera feed, is available on the Weather page. The Management button provides insights into the various committees overseeing the DOT facility. A collection of images captured by the DOT can be found in the Gallery, while archived information is accessible on the Archive page. To view a comprehensive list of publications based on DOT observations, visit the Publications page. If you're planning a trip to the Devasthal observatory, check out the How to Reach page for travel details. To contact us please visit Contact page.
| Catagory | Share in observation time |
| Director's Discretionary Time | 10% of total observable time |
| Indian institutions (competitive basis) | 60% of remaining observable time |
| ARIES (guaranteed time) | 33% of remaining observable time |
| Belgian institutions (guaranteed time) | 07% of remaining observable time |
| Cycle | Call for Proposal | Deadline for Submission |
| C1 (February-May) | 1st November | 1st December |
| C2 (October-January) | 1st July | 1st August |
Observers/Proposers/Authors are encouraged to mention 3.6m DOT in title or abstract of the research publications and also quote inline in the body of text when first appropriate: "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 the Department of Science and Technology, Government of India." In addition, it is mandatory to cite the papers of the telescope and the instrument used. The papers of the telescope and several instruments are listed below:
Observers/Proposers/Authors are additionally requested to acknowledge the DOT observation staff for carrying out the observation in an Acknowledgement section as follows:
"We acknowledge the scientific and technical staff of the 3.6m Devasthal Optical Telescope (DOT), a national facility operated and managed by the Aryabhatta Research Institute of Observational Sciences (ARIES), an autonomous institute under the Department of Science and Technology, Government of India, for their support in facilitating service mode observations and providing the observational data."
ARIES invites proposals from the astronomical community of India and Belgium for observations with 3.6m DOT for the observing cycle from the 1st of February 2025 to the 31st of May 2025 (DOT-2025-C1). The deadline for receiving these proposals is 2nd December, 2024, 23:59:59 hrs Indian Standard Time (UTC+5.5 hrs). India has a 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 http://dopses.aries.res.in
The 3.6m DOT has three cassegrain ports viz. main axial-port, side-port1 and side-port2. Switching the ports within a minute is possible using a fold mirror. In principle, a set of three instruments can be mounted with the telescope and used nearly simultaneously. The TIRCAM2 (infrared imager) and SPIM (optical imager) are permanently mounted on the side-port1 and side-port2 of the telescope, and it is always available for observation, whereas ADFOSC and TANSPEC will be mounted one at a time on the main axial port. The mounting sequence for main-port instruments is ADFOSC and then TANSPEC for two months each. Users' requirements will govern the actual period of the main-port instruments on the telescope. The Auto-guider is now repaired and tested; observers are advised to use it for long exposures. Proposers requesting time on telescope via DOPSES should browse the Instruments and Telescope pages for the latest updates on current sensitivities and upgrades.
ARIES invites proposals from the astronomical community of India and Belgium for observations with 3.6m DOT for the observing cycle from the 1st of October 2024 to the 31st of January 2025 (DOT-2024-C2). The deadline for receiving these proposals is 1st August 2024, 17:00:00 hrs Indian Standard Time (UTC+5.5 hrs). India has a 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 http://dopses.aries.res.in
The 3.6m DOT has three cassegrain ports viz. main axial-port, side-port1 and side-port2. Switching the ports within a minute is possible using a fold mirror. In principle, a set of three instruments can be mounted with the telescope and used nearly simultaneously. The side-port2 is free at the moment. The TIRCAM2 is permanently mounted on the side-port1 of the telescope, and it is always available for observation, whereas other instruments are mounted one at a time on the main axial port.
For cycle DOT-2024-C2, the mounting sequence for main-port instruments is ADFOSC and then TANSPEC for two months each. The actual period on the telescope will be governed by users' requirements. Optical Imager will be available as an optional instrument and will be made available if demanded. Proposers requesting time on telescope via DOPSES are advised to browse through the Instruments and Telescope pages for the latest updates on current sensitivities and upgrades.
