A series of stars near the North celestial pole used as standards in photometric measurements.

उत्तर ध्रुव क्रम

English Usage: The astronomers are studying the north polar sequence for accurate photometric data.

Hindi Usage: खगोलविद उत्तरी ध्रुव क्रम का अध्ययन सटीक फोटोग्राफिक डेटा के लिए कर रहे हैं।