NASA's Swift gamma ray satellite was struck last week by a blast of gamma rays from an event half as old as the observable universe. so violent was the event that had it occurred in the center of our galaxy, the milky Way would have lit up brighter than the noonday sun. Alerted by Swift, the Very Large Telescope in Chile swung to focus on the burst coordinates and captured a spectrum - the peak luminosity was such that the event was probably visible to the naked eye , making it the oldest sight so far seen by man .
Although visible light photons from events so distant are ordinarily shifted into the infrared and out of sight, this explosion was so violent that its expansion front approached the speed of light , offsetting the red shift due to the expanding universe and rendering it visible
British Swift researcher Julian Osborne said yesterday :
" the explosion took place 7.5 billion years ago, the photons have only just reached us. Are the photon's wavelength affected? Yes, the cosmological redshift almost doubled the wavelengths by the time they reached us. (The emitting surface was travelling towards us at a very high fraction of the speed of light however, this causes the pre-cosmologically-redshited photons to have a very much shorter wavelength than they would have in the inertial frame of the emitting surface.
There was no prompt dispersed spectrum obtained unfortunately, although the redshift (and thus distance) was determined from a dispersed spectrum of the afterglow about an hour after the burst. .. were photons emitted in the visible detected?', then the answer is probably, as the REM Italian IR telescope in Chile pointed at the burst within 43 sec and it was still very bright at that time. "