366460
The show was produced for PBS in the U.S. by The Chedd-Angier Production Company , Watertown , Massachusetts ( as was its predecessor , Discover : The World of Science , a companion program to Discover magazine ) , and typically aired once every two to four weeks .
 PBS
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 PBS