See NEET is the examination which you want to give if you are wiling to go for medical courses. So for being an Astronomer NEET will be unnecessary. Now there are no UG astronomy degree courses in India if you wish to go you have two ways. One is to go for BSc Physics hons and then you can go for MSc Astronomy at IIT Indore by qualifying the IIT JAM examination. Apart from this you can also go for BTech in Engineering Physics/Mechanical Engineering etc and then you can qualify the examination of JAM. Apart from that there is TIFR which offers admission to Astronomy and Astrophysics in Integrated PhD for that also you can go for Engineering or a BSc Physics. So overall KCET will be partially beneficial for you to be an astronomer.

To know more about Astronomy visit the link below:

https://www.careers360.com/courses/astronomy-course

I hope this answer helps. All the very best for your future endeavors!