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

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the argument of an imaginary opponent namely “ Is the
time given measured after Sun-rise Sāvana (mean solar)
or Nākṣatra (ie. sidereal)? If it be the former, how is it
you are subtracting the rising times of sA, AB etc. which
are sidereal from your Sāvana units? Further, should you
not take the position of the Sun at Sun-rise namely S',
because the time given is what has elapsed after Sun-rise ?
Also, why should you complicate matters by accepting
Sāvana units when the question is simple if dealt with
sidereal units ?
To this Bhāskara answers as follows —
“ True it is, what you say. Generally in day to day
life, time is given only in Sāvana units and not side-
real. Further you cannot avoid Sāvana measure, for,
in the case of an arc moved by a planet, in its diurnal
circle time is measured in the Sāvana units pertaining
to the planet. (The Sāvana units of a planet are
different from what they are for the Sun depending upon
the arc moved by the planet in question during a day).
These Sāvana units are what are termed Kṣetra-Vibhā-
gātmika or what depend upon the arc covered in the
diurnal path in contradistinction to the Kāla-Vibhāgat-
mika units or sidereal units. (In other words pure time
is what is measured in sidereal units which is a standard
measure, whereas time which has the bias of the motion
of the planet also ie. which we seek to measure by the arc
moved by a planet in its diurnal path, is Kṣetra-Vibhāgāt-
mika). Thus having had to accept the Sāvana measure
also, we seek to proceed on that basis, though we could
convert the Sāvana measure into the sidereal and
proceed without complication ”. The argument which
Bhāskara gives for तात्कालिकीकरण is further as follows.
The measure of the arc SL using the rising times in
asus ie. sidereal units, is the Sāvana measure of the arc
S'L done in sidereal units. Instead of subtracting the
rising time of S'A from the given time converted into