Astronomy

Top 5 colleges where you can pursue an UG degree in astrophysics are mentioned below:
1) Indian Institute of Technology IIT Delhi), New Delhi
2) Indian Centre for Space Physics, Kolkata
3) Tata Institute of Fundamental Research (TIFR) - Department of Astronomy and Astrophysics, Mumbai
4) Madhya Pradesh Birla Institute of Fundamental Research, Bangalore
5) Shivaji University, Kolhapur
Admission process:
Most institutes offering a course in astrophysics follow a merit- based admission process. The process involves an assessment of the candidate on the basis of score at the 10+2 level, and in a relevant national, State, or institute- level entrance test. Regards.

Some of the best colleges to study astrophysics in India are mentioned below:
1) Indian Institute of Technology IIT Delhi), New Delhi
2) Indian Centre for Space Physics, Kolkata
3) Tata Institute of Fundamental Research (TIFR) - Department of Astronomy and Astrophysics, Mumbai
4) Madhya Pradesh Birla Institute of Fundamental Research, Bangalore
5) Shivaji University, Kolhapur
6) Savitribai Phule Pune University : Department of Atmospheric And Space Sciences, Pune
7) Centre for Earth Atmosphere and Weather Modification Technologies (CEA and WMT), Hyderabad
8) Indian Institute of Science (IISc) : Department of Physics, Bangalore
9) Cochin University of Science and Technology : Department of Atmospheric Sciences, Kochi
10) Raman Research Institute, Bangalore
Regards.

Dear Baby!
Currently, you are on the wrong path if you are willing to be astronaut and working in a IT company. The more sophisticated way is to continue your studies.
(1) Do your Master in Aerospace Engineering from Indian Institute of Space Science & Technology, Kerala.
(2) Hence after you MUST have to do Ph.D. in that particular subject from Indian Institute of Science, Bangalore. (*I hope you know why I am mentioning the name of specially these institution).
You know that Astronaut are not like regular employee for space organisation. They are specially build person hired (or trained) for a particular mission. So, don't think that ISRO or NASA or ESA are always recruit Astronauts. They don't do so, unless they plans a manned mission for space region or for ISS. Another thing I would like to say is about your physical fitness. You have to be 100% fit not just from your physic but also from your mind (mental stability). (#) Astronaut is not a position. So, there is no special degree for that. Your Steller academic background, your physical, mental, emotional, biological stability/fitness and the hardcore training will help you to be astronaut. (#) Be in contact with ISRO and its operations. B.Tech in CS is not bad but not a wise choice for Space Science. But this may helps you in Rocket Simulation.
Answer is quite long but I hope this helps.
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Good Luck.