Evans pointed out that the Swift team never announced a GRB discovery and that this was merely a preliminary alert that required urgent attention. GRBs are rare and still poorly understood, so immediate action is needed as soon as a candidate event is detected to ensure Swift and other telescopes can quickly measure the GRB's afterglow that rapidly fades with time.
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So in these cases a choice needs to be made: "Do we assume that these preliminary results are correct and chase the object, risking wasting telescope time? Or do we wait until we know for sure, and miss observing a one-in-a-century event?" Evans asks. Obviously, when time is of the essence, you need as many people looking at that patch of sky to avoid missing astromical history unfolding.
But this was one of those times where an X-ray source fooled the BAT software into thinking a GRB was underway.
Although it is a shame that Andromeda isn't the site of a nearby (but not too nearby) GRB, this is a fine example of science and astronomy at work where cutting edge technology is making real-time observational data available to scientists on the ground. But sometimes on the leading edge of astronomical discovery, there's the occasional false alarm.