HI, You will have to obtain a bachelors degree in Science subjects such as Physics / chemistry/ Mathematics.
Apart from these, some universities offer under graduation course in Astronomy. If you are interested in doing M.Tech courses related to Astronomy, then you can opt for engineering stream.
Engineering courses in streams like Electronics and Communication Engineering, Electrical and Electronics Engineering and Computer Science Engineering will help one to have master level courses in the field of Astronomy.
In the start, At entry level you can get in to the role of Junior Research Fellow, Research Trainee, etc. Job positions exists in firms like NASA, ABAA,  Bhabha Atomic Research Centre (BARC), and Indian Space Research Organization (ISRO).
Department of Science and Technology, Government of India also offer enough career openings.

Hope this helps.
Good Luck.