‘…[A]stronomers suspect it could have been one of the most violent events in the Universe – a gamma ray-burst that, in just a few seconds, could have released as much energy as our Sun in its entire lifetime.If confirmed, this will be the closest gamma-ray burst we’ve ever detected, and will help scientists find out more about these mysterious pulses of energy.Gamma-ray pulses are so powerful, that if one occurred within our galaxy, they could potentially trigger mass extinctions on Earth, explains Dr Alan Duffy, an astronomer at Swinburne University of Technology in Melbourne.’ (Science Alert).
Addendum (thanks to abby): Possibly not.
“We have re-analysed the prompt XRT data on Swift trigger 600114 (GCN Circ.
16332), taking advantage of the event data.
The initial count rate given in GCN Circ. 16332 was based on raw data from
the full field of view, without X-ray event detection, and therefore may
have been affected by other sources in M31, as well as background hot
pixels. Analysis of the event data (not fully available at the time of the
initial circular) shows the count rate of the X-ray source identified in
GCN Circ. 16332 to have been 0.065 +/- 0.012 count s^-1, consistent with
the previous observations of this source [see the 1SXPS catalogue (Evans
et al. 2014): http://www.swift.ac.uk/1SXPS/1SXPS%20J004143.1%2B413420.
We therefore do not believe this source to be in outburst. Instead, it was
a serendipitous constant source in the field of view of a BAT subthreshold