What is the fine-grained topic of the following text: The HST team will be making a final decision on observing SDSS J153817.35+512338.0 based on the observations of May 13/14 and 14/15, and observations from the following two nights will also be essential. Only return the topic.
Final decision on observing SDSS J153817.35+512338.0 by the HST team based on specific observations.