A section of the Udagashanti mantras describes the procedure for observing the rising of Nakshatras in the east. Narayana Iyengar in his paper, on astronomical observations in India in the 2nd millennium BCE, to be published in the Indian Journal of the History of sciences refers to the Udagashanti Mantras. He writes that Sanskrit Pundits as late as the 11th century wrote commentaries on these mantras providing a newer context to the observation of the Heliacal rising of stars. The existence of these commentaries is a proof that the custom verifying astronomical calculations in the Panchang against sky observations was in vogue in the past. It attests to the fact that scientific temperament accompanied religious rituals in India until the arrival of Islamic rule.
An educated section of Indian society today is totally ignorant of such facts and is ready to brand Vedic sciences as fictional. Vedic rituals, invoking the guidance of Devatas in the subtle fields, is certainly in the domain of faith. But the stringent timing requirements and the necessary spatial configurations for rituals had provided the impetus for the blossoming of scientific temper far earlier in the India subcontinent than in any other part of the world. It is worth popularizing the idea that the interpretations of scientific facts in the mantras continued for several millennium. I myself had earlier memorized some sections from the Udagashanti mantras but only realized that some are related to sky observations after finding Narayana Iyengar’s paper.