The COBE satellite has given an adjusted figure of 2.73 thousand as opposed to the typical 3 thousand Kelvins that is associated with it.  
It implies about 5.5 times 10 to the 5th photons per liter and as many as 2 times 10 to the 10th photons per baryon.  It exhibits an anisotropy of about one-tenth of a percent, which is attributed to a Doppler shift caused by the motion of the solar system through it.  The COBE satellite has given an adjusted figure of 2.73 thousand as opposed to the typical 3 thousand Kelvins that is associated with it.  Theory states that it is the cooling remains of energy released at the big bang.  FTP, name this radiation first detected by Penzias and Wilson.
It implies about 5.5 times 10 to the 5th photons per liter and as many as 2 times 10 to the 10th photons per baryon.  
cosmic background radiation or cosmic microwave background radiation