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

507
It is to be noted that these longitudes are the same
given by Brahmagupta originally and copied by S'rīpati
as well as the corrections indicated above. But herein a
mistake was committed as clarified by Bhāskara later in
the end of the chapter namely that the polar longitudes
are subject to what is called Āyanavikāra though the
celestial longitudes are not. We say that the celestial
longitudes are not subject to such an Āyanavikāra ie. that
change due to the phenomenon known as the precession
of equinoxes, because the Hindu system is Nirayana ie.
reckons the longitudes from the first point of Aswinī
which is its zero point instead of reckoning from r. If
longitudes are measured from r, as r is preceeding, the
longitudes of stars will be steadily increasing all at the
same annual rate of precession namely about 50-25"
per year. These increasing longitudes of the modern
system go by the name Sāyana longitudes. It might
be thought that since the polar longitudes also are
measured from Aswinī and along the ecliptic like celestial
longitudes, they also don't vary like the Nirayana celestial
longitudes ; but it is not so, because the effect of precession
on the right ascension and declination of a star have
both their effect upon the polar longitude as well as polar
latitude. We cannot say that Bhāskara did not know
this but we may say that the effect on the polar longitude
and latitudes were construed by him as neglible and
would be appreciable only in the long run.
Verses 4, 5, 6. Sphutas'aras or rectified latitudes
of the stars.
Aswinī 10°- 0 north Ārdrā 11 - 0 south
Bharaṇī 12°- 0 ,, Punarvasū 6 - 0 north
Kṛtticā 4 -30 ,, Puṣyamī 0 - 0 ,,
Rohinī 4 -30 south Asreṣā 7 - 0 south
Mṛgas'irṣa 10 - 0 ,, Makhā 0 - 0 north