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

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polar longitude, using the modern Ayanāṁsas. Since in
this process, we have no definite knowledge of the then
celestial longitude ie. of the Āyanasūnyakāla, the method
of successive approximation is appealed to.
But this method of Bhāskara
may be modified to an easier pro-
cess as follows. Let rL, LS be
the polar longitude and polar lati-
tude of a star as given by Acharyas
in whose time the Hindu first
point of the zodiac coincided
with r. It is required to find rN
and NS the celestial longitude
and latitude which hold good even
today becaus rN and NS are the same as AN, AS, A being
the first point of Aświni and a celestial longitude measured
from A along the ecliptic is not subject to change on account
of precession of the equinoxes as well as the celestial lati-
tude. From the spherical triangle rLM, cot rLM = cos rL
tan ω (1) and from the triangle SNL, tan LN =
cos SL̂N × tan SL = cos rLM tan SL (4) and sin SN =
sin SL × sin SLN = sin SL × sin rLM (5). From (1)
the angle rL̂M is obtained ; substituting this value in (2)
and (3) LN and SN are obtained. Adding LN to rL we
have rN.
Thus the celestial longitude and latitude are found
far more easily and more accurately than from the
laborious method indicated which gives only approximate
results.
Here ends the Bhagrahayutyadhikāra.