In my spare time I like to edit the Wikipedia, but only on topics that interest me (mostly hobby interests). Usually it's just fact checking and little fixes, only most of the time the questions don't have simple answers. If they did, someone would have already fixed them.
Lately I've been interested in gamma rays and gamma-ray astronomy, and the Crab Pulsar keeps getting mentioned. The Wikipedia article Crab Pulsar
http://en.wikipedia.org/wiki/Crab_Pulsar says that the mass is 1.4 solar masses and that the optical pulsar has a diameter of roughly 20 km. However, as someone pointed out on the article's Talk Page, this is not supported by the reference, which only assumes standard values for M and R.
Meanwhile, the Wikipedia article on Crab Nebula says the pulsar is 28-30 km across. Even though this appears to be supported by the reference, a web page at harvard.edu, (
http://chandra.harvard.edu/photo/2006/crab/), this is a tertiary source referenced to here
http://science.nasa.gov/science-news/science-at-nasa/2005/27oct_halloween/ which doesn't mention radius or diameter.
Since posting this question, I've made some progress on finding out the answer. The mass and radius of the crab pulsar are apparently unknown except for the calculated values for neutron stars in general. Even though various astrophysicists have their own theories that are more specific, none of these theories is widely accepted. The canonical values for a (generic) neutron star are 1.4 solar masses and 10 km radius. The range is about 1.2-3.2 solar masses (some put the upper limit as high as 4.8), while the range for radius is either 10-15 km or 10-20 km. Now the question is how to put this into simple language and make sure it's properly referenced.