Astronomy

Physics Research Laboratory (PRL), Ahemadabad is the only institution related to astronomy. So, there is no question of best. It is one and only. However, if you are really interested in astronomy and astrophysics (Space Science), you may consider IIST (WB), IUCAA or IISER (Pune), IISc (Bangalore) and other such institutions. These come at the top when we talk about studies in astronomy and astrophysics.

There are lots of job opportunities in space research field, aeronautical companies, space research laboratories.
Especially in India, DRDO and ISRO have excellent job opportunities for M.Sc Astronomy and Space Physics post graduate students.

Hello Prateek,
To become astronaut there are different yardsticks. It actually depends on requirement. Recently, NASA selected some persons to make them astronauts. They are from quite diverse background.

Your approach and strategy to become an astronaut is excellent. You are further advised to learn flying and obtain CPL license. With your proposed educational qualifications and 1000h of flying you will become eligible to spy for astronaut job.

You are advised to have following two options to workin space Scuence and technology:
(a) M.Sc-PhD in Astrophysics from Indian institute of Astrophysics
(b) B.Tech-M.Tech Aerospace Engineering.
You may opt for any as per your preferences.