There are several examples of irony in "An Astrologer's Day." The most striking example of situational irony is the fact that Guru Nayak comes to the astrologer for help in finding the man who nearly killed him--and the astrologer himself is the very man he is looking for. Guru Nayak does not recognize him because the author has established that it is late at night and the lighting is very bad. Most of the vendors have shut down for the night and turned off their lights. Furthermore, the astrologer has changed his appearance considerably since his nemesis last saw him.
His forehead was resplendent with sacred ash and vermilion, and his eyes sparkled with a sharp abnormal gleam which was really an outcome of a continual searching look for customers, but which his simple clients took to be a prophetic light and felt comforted. The power of his eyes was considerably enhanced by their position, placed as they were between the painted forehead and the dark whiskers which streamed down his cheeks....
In addition to the situational irony, there is considerable dramatic irony in the dialogue. The astrologer amazes Guru Nayak by seemed to know all about him through supernatural power, and this enables the astrologer to persuade his client to give up his search for the man who knifed him and threw him into a well. He assures Guru Nayak that the man he has been looking for is dead.
He took out a pinch of sacred ash and held it to him. "Rub it on your forehead and go home, never travel southward again, and you will live to be a hundred."
"Why should I leave home again?" the other said reflectively. "I was only going away now and then to look for him and to choke out his life if I met him." He shook his head regretfully. "He has escaped my hands. I hope at least he died as he deserved."
"Yes," said the astrologer. "He was crushed under a lorry."
There is more situational irony in the fact that the astrologer is able to bring home a relatively large number of coins because he collected so much from the grateful and happy Guru Nayak. The man who had been striving for so long to find and kill the astrologer ends up paying him generously for his advice to give up his searching and go back to his native village. The astrologer's wife is happy because she will be able to buy some extra treats for their little girl. In a sense, the astrologer deserves the coins he has received from Guru Nayak because he has given his nemesis exactly what he wanted. Guru Nayak wanted satisfaction and closure. He wanted to put an end to his exhausting searching and stay at home for the rest of his life. The astrologer knows nothing about the stars, as the author explains at the beginning, but he is still able to give most of his clients the assurance and satisfaction they really want.