Photo

Sanjay Gosain

Scientist SD
Udaipur Solar Observatory
P. O. Box No: 198, Bari Road, Dewali, Udaipur - 313001, INDIA

E-mail: sgosain@prl.res.in
Tel: +91-294-2453 953 (Main office)+91-294-2453 948 (Island observatory).
Fax: +91-294-2453 902

Current Projects

1. Solar Vector Magnetograph (SVM Phase III)

2. TULIP (LCVR Polarimeter for MAST)

My current research interests include:

  •   Instrumentation: Optical polarimetry & spectroscopy (SVM Phase-III, MAST Polarimeter)
  •   Flare/CME related changes in active regions (Hinode/STEREO Observations)

My interest in solar magnetism includes study of solar photospheric and chromospheric magnetic fields. To study solar magnetic fields, Zeeman effect diagnostics are applied to the measured  polarized spectra of the solar spectral lines. I have developed an instrument "Solar Vector Magnetograph" at USO, Udaipur. Basically, it is an imaging Stokes polarimeters which uses a tunable Fabry-Perot (M/s ICOpticalsystems, UK) as a spectrometer and two quartz quarter-wave plates and a Savart plate as a dual beam polarimeter. I have also developed data reduction and analysis packages to carry out analysis of spectro-polarimetric observations obtained from this instrument. Also, I have worked on the spectro-polarimetric observations from state-of-the-art instruments like Advanced Stokes Polarimeter of HAO/NSO, SacPeak, USA and Spectro-Polarimeter (SP) instrument onboard Japanese space mission HINODE. My current research interests include: (i) Instrumentation (optical polarimetry and spectroscopy), (ii) study of magnetic and velocity fields in sunspot fine-structures and magnetic neutral lines of solar active regions, (iii) flare/CME related changes in solar active regions, (iv) three dimensional reconstruction of erupting filaments using STEREO observations.

RECENT PRESENTATIONS:

2010

1.      Flare Related changes in the Magnetic Non-potentiality and Velocity Field of Solar Active Regions: during August 2010 at NSO, Tucson, USA

2.      Evolution of twist-shear and dip-shear in a flaring delta-sunspot: Hinode observation: during August 2010 at IAU 273 Symposium, Ventura, California, USA

3.      Flare related changes in the solar magnetic and velocity fields : Hinode and MDI observations: during July 2010 at Max Planck Institute for Solar System Physics, Lindau, Germany

4.      3D view of Eruptive Filaments: during July 2010 at 38th COSPAR Gen. Assembly, Bremen, Germany

2009

5.      Coherent Lateral Motion of Penumbral Filaments during X-class Flare: Hinode Observations: during December 2009 at 3rd Hinode Science Meeting, Tokyo, Japan

6.      Solar Magnetic Field Measurements: From Hale to HMI: during September, 2009 at Mohanlal Sukhadia University, Udaipur, India

BOOKS:

1.      Polarimetric studies of the Solar Atmosphere:Employing Tunable Fabry-Perot Etalons for High-Cadence Magnetic Field Measurements

Polarimetric Studies of the Solar Atmosphere: Employing Tunable Fabry-Perot Etalons for High-cadence Solar Magnetic Field Measurements

Publisher: LAP LAMBERT Academic Publishing (September 27, 2010)

ISBN-10: 384335700

ISBN-13: 978-3843357005

PUBLICATIONS:

 

2010

1.      Solar Vector Magnetograph (Phase II): Instrument Status & Vector Field Measurements of Non-flaring Solar Active Regions
Gosain, S. and Venkatakrishnan, P.
Indian Journal of Radio and Space Physics, In Press

2.      Solar Polar Fields During Cycles 21-23 : Correlation with Meridional Flows
Janardhan, P., Susanta, K. B., and Gosain, S.
Solar Physics, Accepted

3.      Acoustic Power Absorption and its Relation with Vector Magnetic Field of a Sunspot
Gosain, S., Mathew, S. K., and Venkatakrishnan, P.
Solar Physics, In Press

4.      Magnetic Non-Potentiality of Solar Active Regions and Peak X-Ray Flux of the Associated Flares
Tiwari, Saniv Kumar, Venkatakrishnan, P. and Gosain, S.
Astrophysical Journal, vol 721, p 622

5.      On the estimate of magnetic non-potentiality of sunspots derived using Hinode SOT/SP observations: Effect of polarimetric noise
Gosain, S., Tiwari, Saniv Kumar and Venkatakrishnan, P.
Astrophysical Journal, vol 720, p 1281

6.      Evolution of twist-shear and dip-shear during X-class flare of 13 December 2006: Hinode observations
Gosain, S. and Venkatakrishnan, P.
Astrophysical Journal Letters, vol 720, p L137

7.      A technique for removing background features in SECCHI/EUVI He II 304 A filtergrams: Application to the filament eruption of 22 May 2008
Artzner, G., Gosain, S. and Schmieder, B.
Solar Physics, vol 262, 437 -447

8.      Estimation of width and inclination of a filament sheet using He II 304 A Observations by STEREO/EUVI
Gosain, S. and Schmieder, B.
Annales Geophysicae, vol 28, 149 -153

9.      Magnetic Field Structures in a Facular Region Observed by THEMIS and Hinode
Guo, Y., Schmieder, B., Bommier, V. and Gosain, S.
Solar Physics, vol 262, 35 -52

2009

10.  HINODE Observations of Coherent Lateral Motion of Penumbral Filaments During a X-Class Flare
Gosain, S., Venkatakrishnan, P., and Tiwari, Sanjiv Kumar
Astrophysical Journal Letters, vol 706, L240 -L245

11.  3D Evolution of a Filament Disappearance Event Observed by STEREO
Gosain, S., Schmieder, B., Venkatakrishnan, P., Chandra, R., and Artzner, G.
Solar Physics, vol 259, 13 -30

12.      Effect of Polarimetric Noise on the Estimation of Twist and Magnetic Energy of Force-Free Fields
Tiwari, Sanjiv Kumar, Venkatakrishnan, P., Gosain, S., and Joshi Jayant
Astrophysical Journal, vol 700, 199 -208

13.      A 2-dimensional Scanning Solar Vector Magnetograph at Udaipur Solar Observatory
Gosain, S. and Venkatakrishnan, P.
Astronomical Society of the Pacific Conference Series, vol 405, 467

2008

14.      Software for interactively visualizing solar vector magnetograms of Udaipur Solar Observatory
Gosain, S., Tiwari Sanjiv, Joshi Jayant, and Venkatakrishnan, P.
Journal of Astrophysics and Astronomy, vol 29, 107 -111

15.      Evolution of Magnetic Helicity in NOAA 10923 Over Three Consecutive Solar Rotations
Tiwari, Sanjiv Kumar, Joshi, Jayant, Gosain, S., and Venkatakrishnan, P.
Turbulence, Dynamos, Accretion Disks, Pulsars and Collective Plasma Processes, vol , 329

16.      Solar Magnetism
Venkatakrishnan, P. and Gosain, S.
Princeton Series in Astrophysics, vol , 39 -60

2006

17.      Solar Vector Magnetograph at Udaipur Solar Observatory: New Results
Gosain, S.
2nd UN/NASA Workshop on International Heliophysical Year and Basic Space Science

18.      Acoustic power and magnetic field orientation in a large sunspot
Gosain, S., Venkatakrishnan, P., and Venugopalan, K.
Proceedings of SOHO 18/GONG 2006/HELAS I, Beyond the spherical Sun, vol 624,

19.      Design and Status of Solar Vector Magnetograph (SVM-I) at Udaipur Solar Observatory
Gosain, S., Venkatakrishnan, P., and Venugopalan, K.
Journal of Astrophysics and Astronomy, vol 27, 285 -292

20.      Hα Observations of 8 June, 2004 Venus Transit
Ambastha, Ashok, Ravindra, B., and Gosain, S.
Solar Physics, vol 233, 171 -184

2005

21.  Preliminary Results of Venus Transit of June 8, 2004 Observed in Hα 6563 A
Ravindra, B., Ambastha, Ashok, and Gosain, S.
Bulletin of the Astronomical Society of India, vol 33, 366 -366

2004

22.  Design of Instrument Control Software for Solar Vector Magnetograph at Udaipur Solar Observatory
Gosain, S., Venkatakrishnan, P., and Venugopalan, K.
Experimental Astronomy, vol 18, 31 -38

2003

23.  Simultaneous Stokes-V diagnostic of a Sunspot using Mg b and Fe I lines
Gosain, S. and Prasad Choudhary, Debi
Solar Physics, vol 217, 119 -132

24.  White Light and Emission Line Polarization of Solar Corona during TSE of June 21, 2001
Ambastha, Ashok and Gosain, S.
Bulletin of the Astronomical Society of India, vol 31, 295 -296

26.  Study of bright points in the off-band Hα filtergrams of active regions
Choudhary, D. P. and Gosain, S.
Astronomische Nachrichten, vol 324, 367 -368

27.  Magnetic and velocity fields of active regions
Choudhary, D. P. and Gosain, S.
Astronomische Nachrichten, vol 324, 362 -363

2002

28.  The Source of a coronal mass ejection in a decayed solar active region
Prasad Choudhary, Debi, Srivastava, Nandita, and Gosain, S.
Astronomy and Astrophysics, vol 395, 257 -262

29.  On Magnetic Flux Imbalance in Solar Active Regions
Choudhary, Debi Prasad, Venkatakrishnan, P., and Gosain, S.
Astrophysical Journal, vol 573, 851 -856

30.  Comparative Study of LiNbO3 and Servo Controlled Air Gap Fabry-Perot Etalons for Solar Application
Debi Prasad, Choudhary and Gosain, S.
Experimental Astronomy, vol 13, 153 -158

AWARDS:

1.    Best Thesis Award by Astronomical Society of India (Feb, 2009).

My Ph.D. thesis : Polarimetric Studies of the Solar Atmosphere

Thesis Supervisors: Prof. P. Venkatakrishnan & Prof. K. Venugopalan.

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Please send enquiries at sgosain@prl.res.in