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

203
ximate statement just like saying that ‘Since 12 Rasis
rise in the course of a sidereal day, so each rasi rises in
1800 asus’ which is far from truth being based on a crude
rule of three. So, Bhāskara says, Acharyas like Aryabhata
insisted on finding the rising times of Dṛkkāṇas, in as
much, as while computing the Lagna or the point of inter-
section of the Ecliptic with the horizon, we will be nearer
the truth by using the rising times of smaller arcs like
Dṛkkāṇas than broadly using those of Rasis.
Verse 61. Bhujāntara correction.
The equation of centre of the Sun multiplied by the
equatorial rising time of the Rāsi occupied by the Sun,
and divided by 1800, and then again multiplied by the
true daily motion of a planet and divided by the number
of asus in a day, is the correction in the planet positive
or negative according as the equation of centre of the Sun
is positive or negative.
Comm. This Bhujāntara correction arising out of
the Sun’s equation of centre is prescribed even for the Sun,
as well as for the other planets. The planets are originally
computed for the rising time of the Mean Sun, whereas
we are interested to know the positions at the True Sun-
rise. The position of the Sun also is originally computed
for his mean rise and is therefore to be rectified to get his
position at his true rise. So even the Sun is not exempt
from the correction. It will be noted here that as the
equation of centre pertains to the eccentricity of the Sun’s
orbit, this correction of Bhujāntara is a correction for the
so-called modern ‘Equation of time due to eccentricity’.
In other words, the Sun’s equation of centre converted
into time is exactly what is called the Equation of time
due to eccentricity.
The formula prescribed for the correction is as follows.
Suppose the Sun is in a particular Rāsi which rises at the
equator in x asus. Let the equation of centre of the Sun be