PSR B1913+16 (or J1915+1606) is a binary pulsar, or a pulsar in a binary star system. A binary pulsar consists of two stars orbiting around each other (around a common center of mass based on the two stars).
This particular binary pulsar, PSR B1913+16 was discovered by Russell Alan Hulse and Joseph Hooton Taylor, Jr., of Princeton University. They were later awarded the 1993 Nobel Prize in Physics based on a claim in the abstract of their paper that this binary pulsar confirms the Theory of General Relativity due to its loss in energy over time, which Hulse and Taylor attributed to the radiation of gravitational waves under the Theory of General Relativity. The claims in the body of the paper itself are more restrained, simply showing that assumptions could be made about the physician attributes of the system (including assuming what their masses are) in order to fit the data to the theory.
In 2004, Professor Taylor co-authored a paper reviewing new data from this binary pulsar. By this time the data diverged from the predictions of the Theory of General Relativity, and a "galactic acceleration term" was introduced to fit the data to the theory. However, a perfect fit was not possible for any set of assumptions for the physical attributes of the system, and a minimum of 0.2% in error was introduced. If the theory were correct, there should be no error because assumptions are made about the physical attributes in order to fit the data to the theory.
Perhaps observing a widening divergence between observation and theory, the authors declared that "it seems unlikely that this test of relativistic gravity will be improved significantly."
No data observed after 2003 have been published about this binary pulsar, which suggests that the data have diverged even further from the predictions of the General Theory of Relativity. It would be easy to post the data on the internet for the public to view and draw their own conclusions.
- J. M. Weisberg and J. H. Taylor, Relativistic Binary Pulsar B1913+16: Thirty Years of Observations and Analysis (July 7, 2004).