IIST offers a MS in Astronomy and Astrophysics based on valid GATE/NEST/UGC NET score.
Eligibility :

BE/B. Tech or equivalent degree in Aerospace Engineering, Aeronautical Engineering, Mechanical Engineering, Chemical Engineering, Civil Engineering, Avionics, Electronics and Communication Engineering, Electrical Engineering, Electronics and Electrical Engineering, Electrical and Electronics Engineering, Electronics and Instrumentation Engineering, Instrumentation and Control Engineering, Physical Sciences, Engineering Science , Instrumentation Engineering, Engineering Physics,Electronics Engineering.
OR
M.S./ M.Sc . in Physics, Space Physics, Space Science, Space Science and Technology

So if you have done your BTech in any of the above you are eligible for it.