Time dilation ,Blue,(Red-) shifting and Lorentz invariants

Time dilation 

Time dilation is a well-known consequence of special relativity and accounts for a change in observed luminosity of

Blue- (Red-) shifting 

Blue shifting (or red shifting) can change the observed luminosity at a particular frequency, but this is not a beaming effect.

Blue-shifting accounts for a change in observed luminosity of

Lorentz invariants

 A more-sophisticated method of deriving the beaming equations starts with the quantity . This quantity is a Lorentz invariant, so the value is the same in different reference frames.