For once, I ain’t even mad: the tale of #GRBm31

The Large Magellanic Cloud (LMC), the largest satellite galaxy of the Milky Way, as seen by the Swift observatory in ultraviolet light. [Credit: NASA/Swift/S. Immler (Goddard) and M. Siegel (Penn State)]

The Large Magellanic Cloud (LMC), the largest satellite galaxy of the Milky Way, as seen by the Swift observatory in ultraviolet light. [Credit: NASA/Swift/S. Immler (Goddard) and M. Siegel (Penn State)]

Tuesday night, the small corner of Twitter I inhabit exploded with activity: the automatic reporting system on the orbiting Swift observatory had sighted an excess of gamma rays from M31, the Andromeda Galaxy. A bunch of us — myself included — spent several hours poring over the scant observational evidence, discussing what might have been the source of this excess. Could it be the most exciting possibility: a short-duration gamma-ray burst (GRB), the sign of two neutron stars colliding? Could it be an ultraluminous X-ray source (ULX), which might be a black hole eating a star? (Both GRB and ULX are descriptions of the burst of light, not the source, but we’ve learned a lot about what makes this kind of signal over the decades.)

We lamented the lack of a gravitational wave observatory to check for a signal, discussed neutrinos, and talked about the expected frequency of this kind of event. Not only was it exciting for the usual suspects — astronomers and science writers — but because it was conducted on the public forum of Twitter, it garnered a lot of attention from non-scientists. A fair number of people participating in the discussion had never even heard of gamma-ray bursts before, so many of us answered questions, sharing what we know about the topic.

But then morning came:

But the reality turned out to be even more disappointing—it wasn’t even a signal worth looking at. A combination of a software glitch and a piece of bad luck lead to a big overestimate of how bright and important the Swift signal appeared to be. Just one day after the news, all of us who were excitedly talking about all the possibilities were left feeling a little embarrassed.

Just a little. Despite the fact that it looks like someone messed up big-time, it’s more properly thought of as a rapid lesson in the science of very rare events—and how they can sometimes make us rush to judgment for the sake of not missing something very important. [Read more…]

I’m often very critical about the rush to publish before all the data is in, so you might think I’m grumpfy about the GRB that wasn’t. But I’m not: I would have been annoyed had the signal persisted to morning and people drawn conclusions before all the data was in. After all, it would have taken between at least 24 to 48 hours to be able to distinguish between a GRB and a ULX, so anyone asserting with confidence that it was one or the other too quickly would be foolish. But getting excited over possibilities? Go right ahead. I think it was good for many people to see how excited astronomers got. Too often scientists are painted as being emotionless or overly analytical, but they’re humans. When something really cool happens, they’re as capable of screaming and running around in circles as everyone. We’re disappointed, of course, but I don’t think the GRB that wasn’t there is anything to regret.


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