5598
The ability to detect and accurately measure the minute value of this anomalous precession ( only 43 arc seconds per tropical century ) is testimony to the sophistication of 19th century astrometry .
 time: tropical century
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: media, plant, vehicle, astronomical object, time, disease, animal, location, person, organization, mythical figure, food, biology, geographical phenomenon, instrument, event 
Text: {0} 
Answer:
 time: tropical century