Sentences of a paragraph are given below in jumbled order. Arrange the sentences in the correct order to form a meaningful and coherent paragraph.
A. Manali Kallat Vainu Bappu is the first Indian astronomer whose name is associated with a comet.
B. He is the first Indian astronomer whose name is associated with an observatory.
C. He has the credit of being the first Indian to preside the International Astronomical Union.
D. He is also associated with an astronomical phenomenon.