The calculated distance (air line) between Saint-Quentin-en-Yvelines and Paris 14 Observatoire is approximately 15 miles respectively 24 kilometers.
By car or train, the actual journey to Paris 14 Observatoire is certainly longer, as only the direct route (as the crow flies) between Saint-Quentin-en-Yvelines and Paris 14 Observatoire has been calculated here.
Air line (approximately)
24 kilometers
13 nautical miles