There is no NIT which offers a program in Astrophysics, but they offers Integrated MSc program in Physics in which you can specialize in Astrophysics and cosmology.

Best NIT's for the Integrated MSc physics program is provided below:

• NIT Warangal.
• NIT Rourkela.
• NIT Suratkal.
• Motilal Nehru NIT Allahabad.
• NIT Trichy.
• NIT Calicut.
• Malviya NIT jaipur.

For more information regarding Astrophysics consider the link below:

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

I hope this helps. Wish you a great day!