सिद्धान्तशिरोमणि: गणिताध्याय (भास्कराचार्य - ग्रहगणित, मध्यमाधिकार व स्पष्टाधिकार सटीक)

221
by Brahmagupta, that Ṛiṣis like Puliśa, Vasiṣṭha and
Garga spoke about these Sukṣmanakṣatras. The
duration of Abhijit calculated as directed is 254' — 18''.
The computation as directed is easy for understanding.
The reason for the durations indicated is not clear but
is to be taken as based on Astrology.
Verses 76, 77. The duration of the planets’ transit
into new Rāśis and the duration of the interval between
successive stars, tithis, Karaṇas and yogas.
The disc of the planet multiplied by 60, and divided
by its daily motion gives the nāḍīs of transit of the
planet from Rāśi to Rāśi. This duration is considered
to be holy for performing Vedic rites. It is the holiest
with respect to the Sun’s transit in particular. A planet
in its transit gives partly holy results not so much as
the Sun, depending upon the nature of the previous and
succeeding Rāśis. The duration of Sandhi for tithis is
got by dividing the disc of the Moon expressed in seconds
by the difference of the daily motions of the Moon and the
Sun; so also with respect to Karaṇas. The Sandhi
between two Nakṣatras is obtained by the same measure
of the disc of the Moon expressed in seconds of arc being
divided by the Moon’s daily motion. The Sandhi between
two yogas is got by dividing the same numerator by the
sum of the daily motions of the Sun and the Moon.
Comm. (1) The Sandhi is the period that elapses
during the transit of the disc concerned between the Rāśis
and nakṣatra divisions. With respect to tithi, Karaṇa
and yoga, the divisions are imaginary not being seen in
the Sky and the disc concerned is that of the Moon, and
not that of the Sun though the Sun’s motion is also taken
into account. We say a transit from a division to another
is current so long as the disc lies partly in the previous
and partly in the latter. So the Sandhi begins when the
disc touches the next division and ends when its hind part