You can definitely go for Mtech or ME in Astrophysics but then you shall lack all basic fundamental to grasp concepts.



Better option is you go for Aerospace or Aeronautical enginnering from top institute ljke IISc, IIST, IIT, NIT.



Getting job in astrophysics based roles is difficult post Btech In IT CSE since both are complete different.



Entire scope and top colleges shared below.



http://www.indiastudychannel.com/resources/164161-Where-to-study-astrophysics-in-India-Eligibility-and-Job-Opportunities.aspx