She did not discover pulsars. She was a lab assistant who, as she was writing the numbers down in the lab book, first noticed that there were pulsar patterns in them.
Being the first to lay eyes on something is not typically what we mean, in science, by discovering it. Or else the guy cleaning the ship's deck in the morning should be rewarded for discovering America.
The prize was awarded to the head of the team as it was a project of his design and his organization. To have split 1/3 of the prize with whatever grad student happened to be keeping the books seems ridiculous.