Astronomy & Astrophysics Labs

The main science goals of this observatory are to observe objects which exhibit variability on various time scales. These include short time scale variables such as delta Scuti stars on the one hand to blazars which are active galactic nuclei exhibiting variability at time scales ranging from years to months, days and hours. This telescope has also been used for the observation of transient objects.  It has also been used extensively for spectroscopic studies of comets. Further details can be found @ https://www.prl.res.in/~miro/telescopes.html#50cm

The 50 cm telescope is one of the several telescopes operated by PRL at its Mount Abu Observatory (MIRO). It was installed in 2010. The telescope is a Planewave Instruments’ CDK20 model mounted on a Mathis Instruments equatorial mount with the Servo II control system provided by Sidereal Technology.  The observatory is also equipped with weather monitoring instruments and an all-sky camera to provide for autonomous observation (robotic) capability. 

It has an EMCCD-based imager with a 3-position polarisation capability.  The total field of view of the setup is 13.3 x 13.3 arcmin.   Another instrument available on this telescope is a compact spectrograph called LISA from Shelyak Instruments with a spectral resolving power of ~1000.   Other instruments are currently being developed, including a large area imager. 

Several PhD students have been trained in this observatory and made use of it for their thesis work on topics ranging from comets to stars to active galactic nuclei.  It has also provided research projects for many B.Tech and M.Tech students.

The 50cm telescope is one of the first fully autonomous telescopes in India.  Many of the hardware and software components were developed in-house and integrated by PRL scientists. 

NISP Lab is a 10,000-class cleanroom with temperature and humidity control. It has an air shower and airlock room to maintain stable conditions inside the lab. The cleanroom has epoxy flooring with copper mesh earthing for ESD protection. It is also equipped with an optical table (2000 mm X 1200 mm X 200 mm) with vibration-isolated legs. It is UPS-powered for working safely with sensitive components.

This laboratory is constructed for developing the Near-infrared Imager Spectrometer and Polarimeter (NISP) for Mt. Abu's 2.5m telescope.  Teledyne H2RG detector for NISP is integrated with our in-house developed cryogenic system under dust free and ESD protective conditions in this lab. Optical setups for characterising the collimator and camera assemblies for NISP are being developed and tested in this lab.  Characterisation of H2RG detector at room temperature and cryogenic conditon is carried out.  Complete integration of NISP optics, detector assembly, cryostat, Dewar and all mechanical systems will be done. Final in-lab characterisation of the instrument will also be done in this lab.  

Staff members associated with this laboratory are currently involved in the development of various backend instruments for PRL 50cm, 1.2m, and 2.5m telescopes.  They have expertise in optics design, electronics hardware design, software development, and mechanical and optomechanical design required for designing instruments.

The laboratory is furnished with a steel core optical table of size ~ 2m x 1.2m with active isolation legs.  This caters to the mounting, assembly, integration, and testing of optical components/barrels/detectors/cameras. Additionally, it is equipped with a vacuum pump and a Helium-based vacuum leak detector instrument.

In-house development and testing of cryostat with vacuum Dewar for NISP Characterization of the H2RG detector at room temperature and cryogenic conditions is carried out.

This is one of the few labs in India where infrared astronomical instrumentation is carried out to develop backend instruments for telescopes.  It has facilities to handle and work with state-of-the-art infrared arrays.

MFOSC optical system laboratory is set up with the aim to develop the backend instrumentation for existing PRL 1.2m and upcoming 2.5m telescopes at Mt. Abu. As the telescopes are optimized for the visible and near-infrared wavelengths of the spectrum, the laboratory would thus focus on the development of both optical and near-infrared aspects of astronomical instrumentation.

MFOSC optical system laboratory is located in PRL’s Thaltej campus. It has
the facility to build, integrate, test and characterize optical
instruments for astronomical applications. The laboratory is equipped with
a variety of tools, cameras, light sources and other accessories necessary
for the design and development of optical astronomical instrumentation.

The laboratory staff members are currently involved in the development of
next-generation instrumentation for PRL 1.2m and 2.5m telescopes. Aspects
of spectro-polarimetry are being investigated, and a program on adaptive
optics system development is initiated with the aim to develop
adaptive-optics assisted near-infrared instrumentation on PRL telescopes.

The laboratory members have expertise in optical design, opto-mechanical
system design, electronics and instrumentation controls and related
software development. The members are involved in the design, modelling,
analysis & simulations, fabrication, assembly-integration-testing (AIT)
and on-sky characterization of the instruments.

The laboratory is equipped with a damped optical table with pneumatic
isolators for vibration controls and is installed inside a soft-wall clean
chamber with an air filter unit for clean air circulation. The set-up is
being used for the assembly-integration-testing (AIT) of various
instruments and short-term optics experiments

The laboratory successfully delivered its first fully in-house developed
instrument named MFOSC-P (Mt. Abu Faint Object Spectrograph and Camera –
Pathfinder) in early 2019, which has been regularly used on the PRL 1.2m
telescope since then. It is an imager-spectrograph that works in the
visible wavelength range. It provides the capabilities of filter-imaging
in B-V-R-I and H-alpha bands as well as low-resolution spectroscopy
(R~500-2000). Being used as a facility instrument since 2019, MFOSC-P has
been used to study a variety of astronomical objects and generated several
international research papers and conference proceeding.

X-ray Astronomy Laboratory of the Experimental X-ray Astronomy Group at PRL contributes to the development, testing, and calibration of X-ray instruments flown on ISRO’s astronomy, planetary, and solar missions such as AstroSat CZTI, Chandrayaan-1 HEX, Chandrayaan-2 XSM, Chandrayaan-3 APXS, and Aditya-L1 ASPEX. Developments towards proposed future astronomy missions such as focusing X-ray telescope, hard X-ray polarimeter, and detector systems for Daksha mission are also pursued in the lab.

The X-ray astronomy lab hosts the Experimental X-ray Astronomy Group of PRL, which focuses on observational studies of various astrophysical X-ray sources ranging from the nearby Sun to distant Gamma Ray Bursts (GRBs) and developing instruments for carrying out the same. The lab members have expertise in designing, developing, and calibrating various kinds of X-ray spectroscopic instruments and X-ray polarimeters and utilizing the observations from such instruments to address various outstanding problems in high-energy astrophysics, solar physics, and occasionally lunar science. 

Initially, the group focused on X-ray detector systems for spectroscopic and polarimetric observations. Some of the major milestones in this domain are the demonstration of the polarimetric capability of AstroSat CZTI, the development of a proof-of-concept model for a focal plane hard X-ray Compton polarimeter, the development of a well-calibrated X-ray spectrometer for solar observations - Chandryaan-2 XSM, which continues successful operations, and successful operation of Chandrayaan-3 APXS resulted in the first in-situ measurements of elemental abundances in the south polar region of the Moon. Ongoing developments in this area include the development of a collimated hard X-ray polarimeter and various detector sub-systems for the proposed Daksha mission.

Since 2018-19, the group has initiated the development of X-ray optics for astronomical X-ray telescopes. The lab continues to develop new facilities for fabricating and characterizing X-ray mirror foil substrates, multi-layer coating for X-ray mirror foils, and its characterization, assembly, and testing of X-ray concentrator optics. 

X-ray optics and X-ray detector laboratories have the following major facilities for designing, developing, and calibrating X-ray instruments:

Facilities and Instruments

• Class 10,000 clean room

• RF Magnetron sputtering system for multi-layer coating 

• Programmable ovens for the production of slumped glass mirror foils

• Glass mirror foil cutting facility with diamond tools

• Vacuum chamber facility with manipulators for testing and calibration of X-ray detectors and payloads

• Optical table and stages for use in purpose-built experimental set up for characterization of X-ray detector systems, mirrors, etc.

• X-ray spectrometers – SDD, CdTe, CZT

• Calibration X-ray sources

• X-ray generators with Au and Ag targets

• Multi-channel pulse processing systems for X-ray detectors - NIM modules

Software tools

• Zeemax for optical design

• Inventor for mechanical design and analysis

• NX for thermal analysis

• Silvaco TCAD for detector simulations

• In-house developed DarpanX and DarsakX for design analysis of multi-layer mirror foils and X-ray telescope

X-ray astronomy lab has contributed to various aspects of design, development, characterization, ground and in-flight calibration, and data analysis of the following instruments that have successfully operated/are being operated in various ISRO missions for planetary science, astronomy, and solar/helio physics

• Chandrayaan-1: High Energy X-ray spectrometer (HEX)

• AstroSat: Cadmium Zinc Telluride Imager (CZTI)

• Chandrayaan-2: Solar X-ray Monitor (XSM)

• Chandrayaan-3: Alpha Particle X-ray Spectrometer (APXS)

• Aditya L1: Aditya Solar Wind Particle EXperiment (ASPEX)

Some recent major results from the experimental X-ray astronomy group using observations from some of these instruments are listed below. Visit the group website for a complete list of publications. 

• “First In-Situ Elemental Abundance Measurement of Lunar High Latitude by Chandrayaan-3 APXS”: Vadawale, S. V., Mithun, N. P. S., Shanmugam, M., Sarbadhikari, A. B., Sinha, R. K., Bhatt, M., Vijayan, S., Srivastava, N., et al. (including 29 more co-authors) Nature, 2024

• “Evolution of Elemental Abundances during B-Class Solar Flares: Soft X-Ray Spectral Measurements with Chandrayaan-2 XSM” Biswajit Mondal, Aveek Sarkar, Santosh V. Vadawale, N. P. S. Mithun, P. Janardhan, Giulio Del Zanna, Helen E. Mason, Urmila Mitra-Kraev, and S. Narendranath. ApJ, 920(1):4, October 2021.

• “Observations of the Quiet Sun during the Deepest Solar Minimum of the Past Century with Chandrayaan-2 XSM: Sub-A-class Microflares outside Active Regions” Vadawale, S. V., Mithun, N. P. S., Mondal, B. Sarkar, A. Janardhan, P., Joshi, B., Bhardwaj, A., Shanmugam, M., Patel, A. R., Adalja, H. L., Goyal, S. K., Ladiya, T., Tiwari, N., Singh, N., Kumar, S. The Astrophysical Journal Letters, 2021, Volume 912, Issue 1, id.L13.

• “Phase-resolved X-ray polarimetry of the Crab pulsar with the AstroSat CZT Imager” Vadawale, S. V., Chattopadhyay, T., Mithun, N. P. S., Rao, A. R., Bhattacharya, D., C., Vibhute, A., Bhalerao, V. B., Dewangan, G. C., Misra, R., Paul, B., Basu, A., Joshi, B. Sreekumar, S., Samuel, E., Priya, P., Vinod, P., Seetha, S. Nature Astronomy, 2018, Volume 2, p. 50-55.

• “Hard X-ray polarimetry with Astrosat-CZTI” Vadawale, S. V., Chattopadhyay, T., Rao, A. R., Bhattacharya, D., Bhalerao, V. B., Vagshette, N., Pawar, P., Sreekumar, S. Astronomy & Astrophysics, 2015, Volume 578, id.A73.

The X-ray astronomy lab has pioneered the design of a novel compact hard X-ray polarimeter. With the additions planned in the next couple of years, this laboratory will be the one of its kind in the country to have the facility to develop X-ray telescopes.

The main objective of the PARAS Lab is to characterize, testing and assembly of various sub-systems related to the development of two high-resolutions spectrographs PARAS-1 and PARAS-2.

The main components of these spectrographs include the optical elements, optomechanical assemblies, and electronic subsystems. These labs have been utilized for installing the optical components into their respective optomechanical holders, aligning them, and conducting individual tests on diffraction elements such as echelle gratings, prisms, and gratings. Additionally, the vacuum chamber that houses all the optical components for PARAS was integrated and tested for vacuum stability in this facility. After placing all the optical components inside the vacuum chamber, initial alignment and testing were also performed here. Regarding the electronic subsystem, the detector and its controller were assembled in this lab as well. The detector requires cooling with LN2, so tests for LN2 chamber hold time and vacuum stability were also conducted here. Characterization of the detector, which includes measuring dark currents, gain, and read noise, was completed in this facility. Before transporting the instruments to the main telescope site, successful test spectra were acquired using calibration lamps.

The PARAS-1 and the PARAS-2 are the major instruments assembled and tested here. The details of these spectrographs can be found here.

1. Baliwal Sanjay, Sharma Rishikesh,, Chakraborty, Abhijit et al., 2024, “Discovery and characterization of a dense sub-Saturn TOI-6651b”,  2024, Astron. & Astrophys., forthcoming article, DOI:10.1051/0004-6361/202450934

2. Abhijit Chakraborty, Kapil Kumar Bharadwaj, Neelam J.S.S.V. Prasad, Rishikesh Sharma, Kevikumar A. Lad, Ashirbad Nayak, Nikitha Jithendran, Vishal Joshi, Vivek Kumar Mishra, Nafees Ahmed, “The PRL 2.5m Telescope and its First Light Instruments: FOC & PARAS-2”, Volume 93, 2024,  No 2 - Proceedings of the 3rd BINA Workshop on the Scientific Potential of the Indo-Belgian Cooperation)DOI: 10.25518/0037-9565.11602

3. A Khandelwal, R Sharma, Chakraborty, Abhijit et al., 2023, “Discovery of a massive giant planet with extreme density around the sub-giant star TOI-4603”,  2023, Astron. & Astrophys., 672, L7. 

4. Khandelwal, Akanksha; Chaturvedi, Priyanka; Chakraborty, Abhijit; Sharma,  Rishikesh; et al., Discovery of an inflated hot Jupiter around a slightly evolved star  TOI-1789; 2022 MNRAS. 509. 3339K 

5. Sharma, Rishikesh; Chakraborty, Abhijit Precision wavelength calibration for  radial velocity measurements using uranium lines between 3800 and 6900A, 2021 ̊ JATIS...7c8005S 

6. Chakraborty, Abhijit; Roy, Arpita; Sharma, Rishikesh; Mahadevan, Suvrath,Chaturvedi, Priyanka; Prasad, Neelam J. S. S. V.; Anandarao, B. G., 2018AJ....156. 3C; Evidence of a Sub-Saturn around EPIC 211945201  

7. Fischer, Debra A.; Anglada-Escude, Guillem; Arriagada, Pamela; Baluev, Roman  V.; Bean, Jacob L.; Bouchy, Francois; Buchhave, Lars A.; Carroll, Thorsten;  Chakraborty, Abhijit; Crepp, Justin R.; and 46 coauthors, 2016, “State of the Field:  Extreme Precision Radial Velocities”, PASP, 128, 066001  

8. Kane, Stephen R.; Wittenmyer, Robert A.; Hinkel, Natalie R.; Roy, Arpita;  Mahadevan, Suvrath; Dragomir, Diana; Matthews, Jaymie M.; Henry, Gregory W.;  Chakraborty, Abhijit; Boyajian, Tabetha S.; and 9 coauthors, 2016, “Evidence for  Reflected Light from the Most Eccentric Exoplanet Known”, ApJ,821, 65 

9. Chakraborty, Abhijit; Mahadevan, Suvrath; Roy, Arpita; Dixit, Vaibhav;  Richardson, Eric Harvey; Dongre, Varun; Pathan, F. M.; Chaturvedi, Priyanka;  Shah, Vishal; Ubale, Girish P.; Anandarao, B. G, 2014, “The PRL Stabilized High Resolution Echelle Fiber-fed Spectrograph: Instrument Description and First Radial  Velocity Results”, PASP, 126, 133-147

The PARAS-1 spectrograph (R~67,000), developed here, was responsible for the country's first exoplanet discovery. The newly developed PARAS-2 spectrograph is an advanced version of PARAS-1, featuring a resolution of 110,000, making it the largest astronomical spectrograph in Asia.