The strong linear polarization of its white glow confirmed Shklovskii's prediction that its nonthermal emission is dominated by synchrotron radiation.  
The thickness of Titan's atmosphere was measured from Titan's X-ray shadow during a rare transit of Titan in front of this object.  The strong linear polarization of its white glow confirmed Shklovskii's prediction that its nonthermal emission is dominated by synchrotron radiation.  Proper motion analysis of its knotty filaments shows that its expansion has accelerated in the past 950 years.  The central object is spinning down from a rotation rate of 30 cycles per second as it transfers rotational energy to the surrounding gas via magnetic dipole radiation.  Located in Taurus, FTP name this remnant of the 1054 supernova which is powered by a central pulsar and inspired Messier to begin his catalog.
The thickness of Titan's atmosphere was measured from Titan's X-ray shadow during a rare transit of Titan in front of this object.  
Crab Nebula or NGC 1952 (accept M1 before "Messier," accept Crab pulsar before "central pulsar," prompt on Taurus A or Taurus X-1)