GRB 101225A

Christmas Burst
Event type	Gamma-ray burst
Date	c. 5.5 billion years ago ; (detected 25 December 2010 4:59 18:38 UTC)
Duration	c. 28 minutes
Constellation	Andromeda
Right ascension	00h 00m 47.51s
Declination	+44° 36′ 01.1″
Distance	c. 5.5 billion ly
Redshift	0.33
Other designations	GRB 101225A
	[edit on Wikidata]

Animations by NASA's Goddard Space Flight Center illustrating the two alternative explanations offered for GRB 101225A, the "Christmas burst."

GRB 101225A, also known as the "Christmas burst", was a cosmic explosion first detected by NASA's Swift observatory on Christmas Day 2010. The gamma-ray emission lasted at least 28 minutes, which is unusually long. Follow-up observations of the burst's afterglow by the Hubble Space Telescope and ground-based observatories were unable to determine the object's distance using spectroscopic methods.

In papers published in the journal Nature, two different groups of astronomers proposed different theories about the event's origin. Sergio Campana's group proposes that the event was caused by a comet crashing onto a neutron star within our own galaxy. Christina Thöne's group prefers a more conventional supernova mechanism, involving a merger between a helium star and a neutron star at a distance of about 5.5 billion light years from Earth.