Astronomy

Hello,
Astrophysics is really a specialized branch of physics and the knowledge of certain areas of physics is a must. Done your graduation in engineering in a civil branch which is not actually related to physics or definitely astrophysics. How to work to help you I am attaching a link that will give you all the required information about different eligibility conditions for the different courses that are conducted by the Indian Institute of Science in Bangalore. https://www.shiksha.com/university/indian-institute-of-science-Bangalore-22350/admission
Best wishes to you.

You can refer to Udemy and other courses. Or you can take some online degree where you can attend lecture and complete your degree in following field.

Astronomy and Astrophysics (Andhra Pradesh) at IISc Bangalore is a research programme Ph.D. and M.Tech Research) runs in a collaboration with IIA: ISRO and RRI. The basic eligibility criteria is given below. Educational qualifications: M.Sc. Or equivalent degree in Physical Sciences/ Mathematical Sciences/ Chemical Sciences or BE / B Tech or equivalent degree in any discipline or Graduates of 4-year Bachelor of Science programmes. So from above B.Tech CSE students are eligible for the asked programme with a valid GATE score.