It has been a long trek - at least longer than what I imagined it would be. On the trek, I am fortunate to have come in touch with a variety of people. Some of them have become close at a personal level too. This is an attempt to convey to the reader, my appreciation for these people who directly or indirectly affected the course of this trek.

Apart from the usual stuff, I was taught by Prof. H. S. Mani, at IIT Kanpur, that ”research is not just another profession, it is a way of life”. I also remember Prof. A.P.Shukla who, in his inimitable way, sparked in his students a desire for learning. I owe my presence in the National Centre for Radio Astrophysics (NCRA) to Prof. Mani, and to Prof. Shukla for making learning interesting, and motivating me into the pursuit of research. I express my deep respectful thanks to them.

Once at NCRA, stepping into that ”way of life”, the fascination of thinking big while keeping one’s feet firmly on ground came with Prof. Govind Swarup, and others at the NCRA. Prof. Swarup’s description, sometimes past midnight, of the design of some mechanical structure (which, I later realized was the GMRT antenna), how to do quick arithmetic (where I was made to play the role akin to that of temporary register of a computer CPU), his introducing me to Fourier Transforms, Aperture Synthesis, and Radio Astronomy in general are the first few steps into that ”way of life” I fondly remember. His later demand that I be able to give quick answers to questions that he ”might throw at me while passing by in the corridors” helped me in many ways. His enthusiasm is even now a source of inspiration. Over the years I have interacted with him a lot. He became the source of guidance, consultations and advice and sometimes even a sink for my outbursts due to problems in personal and professional life. I am all the more thankful to him for this, and hope to continue this relationship in future.

For my thesis, I slowly gravitated towards A. Pramesh Rao probably because of his approach to work and his style of thinking and his scientific interests. He gradually became my unofficial guide at NCRA. During the early stages of the GMRT (and to some extent even now), I learnt from him the tricks of the trade, and thoroughly enjoyed that phase of my thesis and GMRT debugging and I am very thankful to him for that. All along he encouraged me to be independent. Partly because of this, I was able to do large parts of my work independently. Even for work where he was not directly involved or interested, he was and continues to remain an excellent person to bounce off ideas - and I sometimes even receive healthy criticism with equanimity.

Another scientist from whom I learnt a good deal is T.J.Cornwell. The time I spent working with him was very satisfying in terms of work in hand, and in future, as well as in terms of learning directly from someone whose work I admire a lot. I could not pursue that line of work due to limitations of my domestic and professional problems. I may have disappointed him there. However, I continue to find in him a very understanding, supportive and inspiring senior colleague. Tim - my heartfelt thanks to you for everything. I look forward to working together again sometime. The possibility to finally go forward from where we left gives an inviting and positive hue to the future.

I am very grateful to D.J.Saikia (a.k.a. Sykes) for agreeing to become my Official Guide. Besides reading my thesis and providing useful comments/criticisms and contributing his all important signatures to my thesis, his contribution in the role of a more experienced friend and well-wisher was a great support. I remember long sessions where he would patiently listen to my diatribe that I would pour out. His counsel at various points of time, his assistance, and discussions were of great help. His legendary wholehearted laughter (which often reached me in my office with minimal attenuation) and his one-liner punch-lines kept the environment cheerful (though I must add that he is now trying to extort something useful out of me as a ”fee” for his signatures!). Sykes, I am indeed grateful to you for all you have done.

Interaction with Rajaram Nityananda towards the concluding stages of my work, started with what was to become Chapter 7 of my thesis. It has been a very rewarding and fruitful experience. Working with him has been sheer joy, and I hope to do more fruitful work with him in future. I continue to learn from his very broad spectrum of interests. I am grateful to him for his indulgence in often going out of his way to help me out in facing problems on various fronts of life.

I also spent sometime working with K.R. Anantharamaiah of the Raman Research Institute, Bangalore and it was such a pleasure. Although, finally, that work did not go into my thesis, I hope to pursue that line of work with him in the near future. He and Namir Kassim of the Naval Research Labs. became the target for bouncing off many of my ideas. Thank you both for tolerating and helping me.

I wish to also thank S. Ananthkrishnan, Gopal-Krishna, C.R. Subrahmanya, V.K. Kulkarni, M. Vivekananda, and K. Subramaniya, for all the help, cheer and fun they brought in life.

Many thanks to my friend Prem Kumar, who helped at various stages with some drawings, and in printing and binding the thesis.

My close friends Sulekha and Goutam Chattopadhyay contributed towards this effort in ways I find difficult to describe - in any case I wish not to attract severe penalties they would impose on expressing formal ”thanks”. Nonetheless, I would say this much – without my family and them I would not have made it. I also found an excellent companion in Divya Oberoi (”Div”) and Jaishree Oberoi. At Pune, I fondly remember long sessions of discussions on just any thing under the Sun, interspersed with generous helpings of aaloo-paranthas at their home adding spice to our discussions.

Rajiv Singh (RK), Ajit Kulkarni, V.M. Tatke (Maharaj), Ramana Athreya, Nissim Kanekar, Sanjay Upreti, Niraj Upadyay, Ajith Kumar (Ajithum), Hemant Lohkhande - all with their own inimitable and unique personalities, helped eliminate drudgery from work and life in general. Late night strolls, tea/coffee/milk sessions (and lately, sessions of Nissim’s own invention of “Turmeric milk”, in the inviting company of potential new members of this gang) followed by “profound” discussions, hikes in the Sahyadris (particularly the Bhimashankar hike), catching snakes in the NCRA campus and photographing them from distances otherwise considered unsafe, and the music sessions were the activities with all these friends which helped me keep tempo of work and made life enjoyable. My thanks to all of them.

I also wish to thank the entire GMRT staff without whose cooperation and help this work would not have been possible. My special thanks to all the telescope operators (Anirudh, Mangesh, Sanjay, Manisha, Manish, Jayprakash and Jitendra) for all help during observations and keeping the GMRT control room environs cheerful (though again I must remind Mangesh that my investment in the music CD that I contributed to the GMRT Control Room did not give the expected dividends).

I enjoy a very special relationship with my youngest Chacha/Chachi - Mr. Anand Shankar / Ms. Mamta Shankar. I find in them a friend, an elder, a patient listener, concerned counselor/critic and a determined well-wisher who invariably make me feel comfortable and stable in life. Also my brothers-in-law and sisters were great sources of inspiration. My special thanks to them all for all they have done.

I always had, and to some extent still have, faith in the basic goodness of all humans and in the beauty of human relationships. During this trek, I came close to some people whose approach to life and relationships however leaves a nagging doubt in the mind. I am sure that what nature does to us must be handled with care, humility, compassion and love - but sometimes people, even in normal circumstances, can become completely insensitive and prefer going for easier solutions in life. I do not know if some of such people have contributed towards this work - positively or negatively. But I will remember them all - some of them even fondly - for a long time.

I am truly amazed by the patience and determination to constantly show the brighter side of life that my family, particularly my parents showed. Past few years have by far been the roughest patch in life I have walked and I have no doubt that without their patience and faith in me, I would have gone down that slippery path which I had begun to walk. There was nothing to look forward on that path, certainly not a thesis. I dedicate my thesis to them and I hope I have made them happier.

I would like to thank the NCSA Astronomy Digital Image Library (ADIL) for providing some of the images used for the purpose of illustration in this thesis.

The NASA’s Astrophysics Data System was extensively used during the course of this work for locating data, other references available on the web and for building the bibliography database for this thesis.

Most of the work which required computers was done using computers running the GNU/Linux operating system. The software I used was almost entirely from the Open Source movement and I am convinced that without the excellent work of all those GNUians out there, my life would have been more difficult. I wish to thank all those anonymous contributors to the Open Source movement and hope to become part of it by contributing something substantial someday.