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Research Experience
Scientific

Pre- and early 1980s: Soon after my M. Sc. Degree, I worked on a Department of Atomic Energy funded project to develop methods for using the X-ray fluorescence technique to measure the trace element of various samples. The method involved on exposing the test sample to radioactive source. The elements on the sample are excited and consequently emit its characteristic X-rays. By detecting these characteristic X-ray, it is possible to uniquely estimate the trace element and its quantity to parts per million laves. The work carried out during this period is summarized in my M. Phil dissertation, available at Physics Department of Kurukshetra University. After about eight months of working on this project, I left for New Delhi to join Prof. K. L. Chopra, at IIT, for exploring to work on the thin film technology. This was a world-class laboratory, with sophisticated instruments such as scanning electron microscope, Auger spectrometer and other facilities. I worked here for about three months and left for Ahmedabad as selected for Visiting Scientist at Physical Research Laboratory. During my short stay at IIT, I learnt a lot about the methods to produce thin film filters, solar cells and transparent conducting thin films. These early work exposed me to sophisticated electronics and other experimental techniques, and laid foundation my interest in experimental physics.

Planetary Nebula: I have participated in observing the planetary nebulae with a Fabry-Perot interferometer (pressure scanning) coupled with one-meter telescope of Vainu Bappu Observatory, Kavalur, India during 1982-1984. An extensive survey of literature was made to find out the relationship between the expansion velocities of the gas in the planetary nebulae with their surface brightness. It was found that the planetary nebulae with binary nuclei have in general a lower expansion velocity of the shell material.

Comets: During 1984-1989, I was working for my Ph. D. thesis. The topic of the thesis was to study the interaction of solar wind with Cometary plasma. The 1985-86 apparition of Halley's comet was a unique opportunity for using a 35 cm class telescope with sophisticated back-end instrumentation to study this process. With the aim of studying the origin of several species in comet atmosphere and their interaction with the solar wind, a 35 cm telescope was set up at Gurusekhar, Mt. Abu, India. About 700 comet images were taken with the standard International Halley Watch (IHW) filters and several Fabry-Perot interferograms in Ha, [OI], C and sodium emission line during an extensive observing session of 8 months. Subsequently, they were digitized with a computer controlled PDS 1010 M (Perkin-Elmor made) microdensitometer at IIA, Bangalore. The digital data were processed by using the image processing technique at the National Astronomical Processing Facility, Ooty. Several interesting results are published in various scientific journals.

Soon after submitting the Ph. D. thesis, I got an opportunity to visit the observatory of Besancon in France and work on International Ultraviolet Explorer observations of the comets with Prof. M. Festou. We estimated the UV color of 36 comets (old and new in Oort sense) and found that it is 60% redder per 1000 at 2900 A and 120% per 1000 A at 3000 A. We also noticed that the dust color of comet Halley did not change during a major outburst on 30 Dec. 1985, during which the dust production rate increased 5 folds. This indicated the uniform composition of cometary nucleus. Our Mie calculation shows that cometary grains do not have the resemblance with the terrestrial samples.

Galactic HII regions: Fabry-Perot interferometers are ideal for observing the extended sources such as HII regions. We used our compact image intensifier based FP spectrometer in 1989-1991 to study the kinematics of some of these objects during my short stay at PRL following the Ph. D. The Fabry-Perot interferograms of Orion and M8 in (SII) line at 671.5 and 673.1 nm were obtained with 1m telescope of Vainu Bappu observatory at Kavalur, India. The results of this work are reported in the Ph. D. thesis of Dr. K. P. Raju and published in the journals.

I came to Max-Planck institute for Aeronomy at Lindau with a Post-Doctoral position and spent here about two years. During this time, I worked on the observation of comets and Jovian plasma tours. I used a Zeiss made focal reducer and tunable Fabry-Perot interferometer with one and two-meter class telescopes at Calar-Alto, Spain, to study these objects.

Extra-galactic objects: In 1991-92 I spent six months at Inter University Center for Astronomy and Astrophysics. During this time, I designed a Faint Object spectrograph and made observation of the elliptical galaxies using 2.3 meter Vainu Bappu telescope and CCD camera.

Solar Physics: In 1992, I joined Udaipur Solar Observatory of Physical Research Laboratory as a faculty member. Since then, I have been working in the field of Solar Physics. My primary interest has been the study of solar magnetism. Apart from the regular solar physics, I have also conducted eclipse experiment. During 24 Oct. 1995 total solar eclipse, I have conducted an experiment to detect the circum solar dust ring at 4 solar radii from the sun which is supposed to be observable during the minimum phase of the solar activity cycle. We did not detect the dust ring signature with our instrument, there by rulings out the existence of an intense ring structure even at the time of solar activity minimum period.

Technical

Instrumentation:

1. A lightweight imaging interferometer for 35 cm telescope was made using a Gen II image intensifier. The instrument was extensively used at Gurusekhar Observatory with 35 cm telescope for obtaining comet Halley images and interferograms. The instrument was also used for studying the HII regions.

2. A Fabry-Perot spectrometer employing the Piezo-electrically scanning was designed for studying the weak extended astronomical objects. An ET 85 etalon (Queens gate Inc. made) and EMI photon counting photomultiplier tube was used with a 8085 microprocessor based computer system for controlling the instrument. This instrument was successfully used with 1 m telescope at Vainu Bappu Observatory, Kavalur and line profiles of Orion Nebula, M8 and comet Halley were obtained in Ha, [OI] and Na D lines.

3. A LiNbO3 Fabry-Perot tunable narrow band filter was designed and fabricated at USO, PRL. This filter was used in video magnetograph. Besides, a computer controlled optical testing laboratory is also established to develop solar instruments.

4. A Total Eclipse polarimeter, which was completely automatic and computer controlled was developed to observe the total solar eclipse on 24 Oct. 1995. This instrument successfully acquired 30 images of solar corona with nine different combinations of filters and Polaroid orientation within 47 seconds of totality time of the eclipse.

5. A long slit (6 arc min) grating based Solar Spectrograph was built with the Coude telescope at the Island observatory of Udaipur. Prominence spectrum in He D3 was obtained using this spectrograph. Using tunable KD*P electro-optic modulators, Stokes profiles of the solar active regions were also obtained. By using a high gain optical CCD, spectrum of prominence in 10830 were obtained.

6. A state of the art Optics testing laboratory was established at the new campus of Udaipur Solar Observatory.

7. Comparative study of LiNbO3 and air gap servo-controlled Fabry-Perot etalons for solar application.

8. Multi-Wavelength solar vector magnetograph using KD*P electro-optic modulators and ISOON FP filters is being built. (On-going at MSFC/NASA)

Computer Software:

In 1986-89, I was actively involved in developing a software package in collaboration with the image-processing laboratory of Space Application Center, Ahmedabad. This package aimed at analyzing the comet Halley images. I have extensively used the Astronomical Image Processing System (AIPS) package developed by NRAO, USA to enhance a faint Fabry-Perot interferogram. The outer fringes with less contrast and the fringe distortions were clearly identifiable in the enhanced images. At MPIAe, Lindau, Germany I have used the MIDAS image processing package extensively. At IUCAA and USO, PRL I used the IRAF package in Unix environment Sun and HP workstations.

Presently, I frequently use IDL, C++ and visual C++ for most of my work. Besides, I always try to learn any other software that might meet my short-term needs like Code V and Zemax (for optical design).

Field Experience

1. 1m telescope of Vainu Bappu Observatory, Kavalur, India was used on several occasions to carry out the emission line study of extended objects with pressure scanned, Piezo-electrically scanned Fabry-Perot Interferometer.

2. At Gurusekhar, Mt. Abu, India a mini observatory with a 35 cm telescope was set up for observing Halley's comet during 1985-86. An extensive observing session spreading over 8 months was undertaken.

3. 1 m telescope at Hoher List, Bonn, Germany was used to obtain the Fabry-Perot spectroscopic observations of comet Levy and CCD images of IC 59 in H and (SII) emission lines.

4. 2.2m Telescope at the Observatorium Calar Alto was used to record the sodium cloud associated with Io and the plasma tours around Jupiter.

5. 2.3m telescope of Vainu Bappu Observatory; Kavalur, India was used for CCD observations of elliptical galaxies.

5. At Udaipur Solar Observatory, observations with the Spar telescope and Fabry-Perot filter.

6. At Kalpi, UP, I established a camp with 10 scientists and engineers to observe the total solar eclipse of 24th October 1995.

7. I have taken part in observing the solar active regions in IR wavelengths with Dr. W. C. Livingston and testing of Near Infrared Magnetograph II at Mc-Math facility of NSO/KP.

8. I have conducted four observing sessions at NSO/SP Dick Dunn Vacuum telescope during last five years.





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Last updated: February 5, 2005