[stingraycharles]

Both wrong; from the site:

"Nightwatch got its name from the famous painting The Night Watch by Dutch painter Rembrandt van Rijn. The masterpiece is prominently displayed in the Rijksmuseum, in Amsterdam - The Netherlands".

http://nightwatchjs.org/guide

[mbq]

...which was called such because the painting got dirty and buried under tons of varnish; the actual title is "The Company of captain Frans Banning Cocq and lieutenant Willem van Ruytenburch preparing to march out."