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I specialize in near-IR and optical instrumentation, & extra-solar planets


At PRL I initiated for the first time in India a dedicated program on detection of Extra-Solar Planets using the techniques of precision radial velocity measurements (spectroscopy).  The program was started in 2008 under which I designed and build an Echelle Spectrograph under temperature control and Vacuum. The precision radial velocity measurements of stars is obtained using a fiber-fed optical echelle spectrograph at R~67,000 (from 3700A to 9000A).  The spectrograph saw first light in April 2010 and after many engineering runs the science observations were started from mid 2012.  It is coupled with our 1.2m Telescope at Gurushikar, Mt. Abu. The spectrograph is under vacuum (0.05 to 0.1mbar) and temperature controlled (0.005C at 24.55C). We are also following some of the bright targets between 8th and 10th magnitudes from TESS/K2 candidates that are publicly announced by these programs.  The PRL exoplanet is known as PARAS (Prl Advanced Radial-velocity Abu-sky Search).



PRL 2.5m Telescope Project and PARAS-2 Project


In the year 2016, the PRL initiated the the PRL 2.5m telescope project with state of art Active Optics systems on the primary mirror and overall wave front error of 70nm, which makes is it the most precise telescope in terms of image quality in the country. During the factory acceptance test at M/s. AMOS, Belgium facility, 0.3 arcsec FWHM of star images were observed using speckle imaging in the V band. The 2.5m telescope is now supposed to see the first light early 2022.


PARAS-2 in the line of PARAS will be a new next generation PARAS instrument with Resolution at R~100,000 and will be coupled to the telescope with octagonal fibers and the telescope image psf will be controlled by a fast tip/tilt system (working up to 20Hz). PARAS-2 like PARAS will be under vacuum and temperature control with target goal of sub-1m/s precision on bright targets. PARAS is designed and built on the line HARAPS. Details of PARAS-2 design can be found in: PARAS-2 precision radial velocimeter: optical and mechanical design of a fiber-fed high resolution spectrograph under vacuum and temperature control    2018SPIE10702E..6GC




The team members of the PARAS/ PARAS2 programs are:


1)    Mr. Kapil Kumar, Engineer SD

2)    Mr. Neelam Prasad, Engineer SD

3)    Mr. Rishikesh Sharma, Scientific Assistant

4)    Mr. Kevi Kumar Lad, Engineer SC

5)    Mr. Ashirbad Nayak, Engineer SC

6)    Mr. Dishendra , Scientific Assistant


Current PhD Student working in the PARAS Project: Ms. Akanksha Khandelwal, Senior Research Scholar


Past PhD Student who worked in the PARAS Project: Dr. Priyanka Chaturvedi, finished her PhD work in August 2016, currently is a Post-Doctoral Research Fellow, at TLS, Tautenburg, Germany




Important exoplanet or brown-dwarf discoveries from PARAS:


“Discovery of an inflated hot Jupiter around a slightly evolved star TOI-1789” 2021arXiv210608660K   Submitted to MNRAS (under review at present)


TOI-503: The First Known Brown-dwarf Am-star Binary from the TESS Mission”. The Astronomical Journal,  arXiv:1909.07984  Bibcode:2020AJ....159..151S doi: 10.3847/1538-3881/ab7245


"Evidence of a Sub-Saturn around Epic 211945201". The Astronomical Journal. arXiv:1805.03466. Bibcode:2018AJ....156....3C. doi:10.3847/1538-3881/aac436



Other significant publications from PARAS:


“Masses and Radii of Four Very Low-mass Stars in F+M Eclipsing Binary Systems”. The Astronomical Journal, 2018AJ....156...27C


Review Article:  State of the Field: Extreme Precision Radial Velocities  PASP, 2016PASP..128f6001F  


 Evidence for Reflected Light from the Most Eccentric Exoplanet Known”   2016ApJ...821...65K


Determination of mass and orbital parameters of a low-mass star HD 213597B”   2014MNRAS.442.3737C


“The PRL Stabilized High-Resolution Echelle Fiber-fed Spectrograph: Instrument Description and First Radial Velocity Results”   2014PASP..126..133C




We at PRL had organized an International Workshop on Radial Velocity and exoplanets in the year 2013:


The workshop was held on Jan 21 & 22 of 2013. Some of the International participants of the workshop were Prof. Michel Mayor & Dr. Francesco Pepe from Geneva Observatory, Switzerland, Prof. Alain Leger from IAS, France, Dr. Suvrath Mahadevan from Penn State University, US and Prof. David Latham & Prof. Andrew Szentgyorgyi from SAO, Harvard University, US. Clicking on their respective names the presentations of these people can be downloaded. Please note that these presentations are copyright materials of individual speakers.  They should not be used for any public event or any newspaper printing, or any such events and permission must be taken from these individuals. 




Other important publications in the field of Astronomical Instrumentation and related fields to exoplanets like high contrast imaging:


1) 10-7 contrast ratio at 4.5l/D: New results obtained in laboratory experiments using nano-fabricated coronagraph and multi-Gaussian shaped pupil masks. Abhijit Chakraborty, Laird A. Thompson, & Michael Rogosky, 2005, Optics Express, vol. 13, Issue 7, p.2394


 2) Evidence of Planetesimal Infall onto the Very Young Herbig Be Star LkHalpha 234. Abhijit Chakraborty, Jian Ge, & Suvrath Mahadevan, 2004, ApJLetters, 606, 69


3) Unveiling Su Aurigae in the near Infrared: New high spatial resolution results using Adaptive Optics. Abhijit Chakraborty & Jian Ge 2004, AJ, 127, 2898


4) First high Contrast Imaging using a Gaussian aperture pupil mask. J.H. Debes, J. Ge, A. Chakraborty, 2002, ApJLetters, 572L, 165. 


5) Progress with UnISIS:  a Rayleigh Laser Guided Adaptive Optics System.  2004.  L.A. Thompson, S.W. Teare, Y.-H. Xiong, A. Chakraborty, R. Gruendl, Proc. SPIE., 5490.


 6) Design and Performance of a Versatile Penn State near IR Imager and Spectrograph. Jian Ge, Abhijit Chakraborty, John Debes, Deqing Ren & Jerry Friedman, 2003, SPIE,      4841, 1503.


7)  Adaptive Optics High Resolution IR Spectroscopy with Silicon Grisms and Immersion Gratings. Jian Ge, Dan McDavitt, Abhijit Chakraborty, John Bernecker & Shane Miller 2003, SPIE, 4839






Dr. Abhijit Chakraborty

Professor, and head of the Astronomy & Astrophysics Division,

Project Director, PRL 2.5m telescope

Physical Research Laboratory

Ahmedabad – 380009

Gujarat, INDIA