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

205
(4) The maximum equation of centre in the Sun
has a magnitude = 13 2°/3 × 1/2π = 41/3 × 7/44 = 287/132 = 2° — 10'
Converting this into time at the rate of 15° per hour
(since in one hour diurnal rotation of the earth is equal to
15°) we have 13/6 × 4 minutes = 26/3 = 8'—40''. The maxi-
mum equation of centre according to modern astronomy
is 2e expressed in radiaus where e = 1/60 (.0167339) = 2 × 1/60
radiaus = 2 × 1/60 × (180 × 7)/22 degrees = 21°/11 = 1°—54' — 33'.
As such the max. Equation of time due to eccentricity is
21/11 × 4' = 84'/11 = 7'—38''. The small difference in the
two values arises out of the difference in the max. equ-
ations of centre. Any way it is clear that, in as much as
the Bhujāntara correction is necessitated on account of
the equation of centre in the Sun, to obtain the planetary
positions computed for the mean Sunrise at the time of
True Sunrise, the Bhujāntara correction is a correction in
the planetary position, on account of the equation of time
due to eccentricity. The max. correction to be effected in
even the quick moving Moon amounts to (8 × 790)/(24 × 60) = 79/18 =
4'—23.3''.
(5) We have said in the translation of the verse.
‘The asus in the Right ascention of the mean Sun’,
where what exactly is stated by Bhāskara is, the time of
rising of the small arc covered by the Sun in the particular
Sāyana Rasi in which the Mean Sun is, (भुक्तासवः) together
with the rising times of the previous Sāyana Rasis covered
by the Sun. The meaning is therefore the rising time of
an arc of the ecliptic equal to the Sāyana longitude of the
ecliptic which is measured by his Right ascension at the

rate of 15° per hour or 6° per nadi or 10 Vinādis per degree
or 60 asus per 60 minutes of arc or as many asus as there
are minutes of arc in the right ascension of the mean Sun.
So, what is stated by Bhāskara is the difference of the
minutes of arc in the mean longitude of the Sun and the
minutes of arc in his right ascension ie. (l—a) expressed
in minutes. We know that the total equation of time
arising out of unequal motion in the true longitude of the
Sun ie. ☉ in comparision with the equal motion in his
right ascension ie. a is measured by ☉—a which may be
expressed as (☉—l) + (l—a) where l is his mean longi-
tude, ☉—l = Equation of centre and so the time
expressed by ☉—l is the equation of time due to obliquity.
The difference l—a arises out of the obliquity of the
ecliptic and so the time expressed by l—a is the equation
of time due to obliquity. We have the modern formula
Cos ω = tan a / tan l so that (1 — cos ω) / (1 + cos ω) = (tan a — tan l) / (tan a + tan l) =
(sin a — l) / (sin a + l)
∴ Sin (a — l) = tan² ω/2 sin (a + l). As a is very
nearly equal to l, we could write, when expressed in
radiaus a—l = tan² ω/2 sin 2l. Thus the maximum
difference between a and l arises when 2l = 90° ie. l = 45
degrees ie. at the mid-point of the first quadrant; the mini-
mum difference is when 2l = 270 ie. l = 135 ie. at the middle
point of the 2nd quadrant. Also the numerical magnitudes
of the max. as well as the minimum value are each tan² ω/2
ie. they are equal. Since this is expressed in radiaus,
converting into time the numerical value of the max. and
minimum equation of time due to obliquity is 9.87′. Thus
we can write l—a = 9.87′ sin 2l. Again where l = 225,
2l = 450 so that l—a will have a positive max.; and again
when l = 315, 2l = 630 so that l—a will have a negative
maximum value. Also when l has values 0, 90, 180, 270 it
is zero. Thus the equation of time due to obliquity is zero
at ♈, ie. the vernal equinox; +ve in the first quadrant

. 207
increasing from zero to 45 degrees and then decreasing
from 45° to 90°; assuming the value zero at 90°, then
negative in the second quadrant negatively increasing from
zero to a maximum as l increases from 90° to 135°, and
then negatively decreasing from the maximum value to
zero at the end of the second quadrant ; again behaving in
the 3rd quadrant as in the first and in the fourth as in the
second.
(6) It was stated by Mr. Mazumdar in his introduction
to the Siddhānta S'ekhara of S'ripati published by the
Calcutta University as well as by pandit Babuaji Misra,
the editor thereof that this Udayāntara correction was
first mentioned by S'ripati, and it meant equation of time
due to obliquity. In fact S'ripati states (Verse I ch. eleven)
“ अन्त्यभ्रमेण गुणिता रविबाहुजीवाऽभीष्टभ्रमेण विहृता, फलकार्मुकेण,
बाहोः कलासु रहितास्ववशेषकं ते, यातासवो युग्मयुजोः पदयोः धनर्णम् ”
l expressed in minutes — H sin⁻¹ (H sin ☉ H cos ω / H cos δ) express-
ed in asus = what are called elapsed asus and are +ve,
+ve, +ve and —ve in the successive quadrants. We saw
before that H sin α = (H sin ☉ H cos ω / H cos δ) so that S'ripati
meant l - α, the former expressed in minutes of arc and
the latter in asus, or what is the same (l—α) both expressed
in minutes or asus. These give the gain of l over α.
Immediately after this verse S'ripati goes to a different
topic, and never mentions (as understood from the printed
text) any further details as to what is to be done with
these Yātāsus. Since Bhāskara says explicitly that for
these Yātāsus, the planets are to be corrected, we may
surmise that there should have been in S'ripati's text also
another verse detailing the usage of those asus.
(7) We shall now attend to what Bhāskara gives by
way of explanation of the verses in question, The Ahar-

208
gaṇa found by us is what is called Madhyama Sāvana-
ahargaṇa or number of days according to mean solar
reckoning, a reckoning made on the basis of taking
uniform motion of the Sun in right ascension. The
planets computed for the Sun-rise on this basis, are to be
corrected for the true Sun-rise which goes according to the
measure of ☉ ie. the true longitude of the Sun. But in
the name of Bhujāntara we have-effected the correction
for ☉ - l ; so what remains is to effect correction for l - a.
This correction is known as Udayāntara.
In other words, since we could not compute the
Sphuṭa Sāvana-ahargaṇa, when we deem that x days
have elapsed according to the mean solar reckoning from,
the epoch upto the mean Sun-rise x ± f might have
elapsed according to Sphuṭa Sāvana-ahargaṇa where f
is a fraction. A correction is to be effected for this
fraction f of a day and it is of the form ☉ - a =
☉ - l + l - a. In the beginning Bhāskara said that mean
planets are had being computed out of the mean solar
ahargaṇa, at the time when the mean Sun is about the
eastern horizon of the equator. Why did he say ‘about
the horizon’? It is because the mean solar ahargaṇa
indicates a Sun-rise on the basis of equal motion in right
ascension whereas on the basis of equal motion in l, he
would be about the horizon. Had we been able to compute
Sphuṭa-Sāvana-ahargaṇa, we could have got direct the
planetary position when the true Sun is on the horizon.
The correction for the difference in ☉ and l having been
attended to through Bhujāntara, we are now to attend to
the correction for the difference l - a.
Verse 64. Another way of looking at the same.
Had we obtained the Ahargaṇa in terms of the local
risings of the Rasis in the place of the equatorial, and
computed the planetary positions for the local true Sun-
rise obtained that way, we would have done the three

209
corrections namely Bhujāntara, Chara and the Udayāntara
as well.
Comm. The correction of chara arises out of the
difference between the equatorial risings and local risings
of the mean Sun. The local mean Sun pertaing again to
uniform motion along the celestial equator Udayāntara
has to be effected for l—a, ie. for the local mean Sun on
the ecliptic. Thus we have obtained the planetary posi-
tions for the local mean Sun-rise and to obtain them for
the True Sun-rise, Bhujāntara is to be effected.
Verse 65. An alternative method of effecting the
Udayāntara correction.
Double the H sine of the Sāyana longitude of the Sun
derived out of the smaller H sin-table, being multiplied
by the daily motion of the planet and divided by 270 and
the result in seconds of arc is to be corrected in the plane-
tary position positive or negative according as the Sun is
in the even or odd quadrants.
Comm. (1) In symbols the correction indicated is
(m H sin 2l) / 270 where m is the planet's mean daily motion in
minutes of arc, l the longitude of the mean Sun, and
H sine is taken where the radius = 120. In the commen-
tary under the verse, Bhāskara adds 'Each quadrant of
the eclipse rises (at the equator) in ¼th of a day but
each Rāśi does not rise in 1/12 of a day. Since this
Udayāntara correction vanishes when the Sun is at the
ends of quadrants it must be construed that this
correction increases positively or negatively from the
beginning of the quadrant to the middle and decreases
from the middle to the end of a quadrant. Saying that a
particular Rāśi rises at the equator in n nādikās is only
an approximate statement since the Rāśi does not rise
uniformly. That is why astronomers like Aryabhata
27

stipulated finding the risings of smaller arcs like horas and
Dṛkkāṇas. Find (H sin l × H cos ω) / (H cos δ) ie. H sin α. Take
the asus in the arc of this H sine ie. find α in minutes.
Then l - α gives the number of asus for which the correct-
ion in the planetary position is to be effected, for, by
these asus the True Sun-rise is accelerated or belated. In
the middle of a quadrant these asus will be a little above
26 Vinadis. To obtain them at any point of the quadrant,
take H sin 2l as the argument so that the maximum correct-
ion will be had at the middle of the quadrant by this
argument. Then the rule of three is ‘ If by 120 as radius,
we have 26 Vinadis, what shall we have for H sin 2l ?’
The result is (H sin 2l × 26) / 120 = (H sin 2l) / 4½ approximately.
Then another rule of three. “ If by 60 Vinadis we have
m' of the planetary motion, where the daily motion of the
planet is m°, what shall we have for (H sin 2l) / 4½ ?” The
result is (H sin 2l × m) / (60 × 4½) minutes = (H sin 2l × m) / 270 . Then
the sign of the correction is clear.
(2) We shall now prove Bhāskara’s statement that
at the middle of the quadrant, the correction is 26 Vinadis.
We saw above that l - α = tan² ω/2 H sin 2l. It is really
creditable on the part of Bhāskara to have seen by intuit-
ion that the argument is H sin 2l. The maximum
correction is therefore tan² ω/2 expressed in asus or minu-
tes of arc. Let x = tan² ω/2
log x = 2 log tan ω/2. Take ω = 24
Then log x = 2 × 1̄.3275 = 2̄.6550
∴ x = ·04519 radian = 155 minutes of arc ie.
155 asus = 155 / 6 = 26 apply.

211
(3) Taking the case of the Moon, the max correct-
ion amounts to (790 × 120) / 270 = 5' — 51''.
Verses 66, 67. The computation of Tithi, Nakṣatra
and Yoga.
The elongation of the Moon ie. the excess of the
Moon's longitude over that of the Sun in degrees. (In
case the former is smaller, add 360° to it and subtract
Sun's longitude) being divided by 12 and 6, the quotients
represent the elapsed tithis and Karaṇas. If the elapsed
Karanas are K, count K — 1 beginning from Bava to
get the current Karaṇa and count from Śakuni to get
the current one beginning from the mid-moment of
Kṛṣṇachaturdasī. Take again the planetary position or
that of the Moon in particular as well as the sum of
the longitudes of the Sun and the Moon both expressed
in minutes of arc and divided by 800. The first quotient
gives the elapsed stars ie. the Stars covered by the planet
or the Moon; whereas the second quotient gives the
elapsed Karaṇas. Then take the remainders in seconds
and divide by the respective daily motions in minutes i.e.
in the case of the planets or the Moon divide by their
respective motions and in the case of yogas divide by the
sum of the motions of the Sun and the Moon. Then the
results give the times in nādīs as to how much the next
nakṣatra or yoga have elapsed. If it be required to find
as to how long the next nakṣatra or yoga will last,
substract the remainder from 800, and divide by the daily
motions in minutes as mentioned above. The results
give as to how many nādīs beginning from the morning
concerned, the next nakṣatra or yoga will last.
Comm. (1) A lunation i.e. the time from the moment
of New Moon to the next New Moon is divided into
30 parts called Tithis. Their names are pratipat, Dwitiyā
etc. upto the 15th purnima or full Moon and again

212
pratipat, Dwitīyā etc. upto the 30th i.e. Amāvāsyā or New
Moon. Thus pratipat starts when ☾ = ☉ i.e. when the
longitude of the Moon is equal to that of the Sun i.e.
from the moment of New Moon when the Moon is in
conjunction with the Sun. अमा सह = वसतः सूर्य्याचन्द्रमसावस्या
मित्यमावस्या i.e. Amāvāsyā is that point of time when
the Sun and the Moon are together. Pratipat lasts
till ☾ = ☉ + 12°; then Dwitīyā begins and lasts till
☾ = ☉ + 24; Thus purnima begins from the moment
when ☾ = ☉ + 168 and lasts till ☾ = ☉ + 180° and
Amāvasyā begins when ☾ = ☉ + 348 and lasts till ☾ is
again equal to ☉ Thus a tithi is the time that is taken
by the Moon to overcome the Sun by 12° beginning from
the moment of New Moon. In other words the tithi is a
measure of the phase of the Moon with a particular
convention.
(2) In modern astronomy the phase of the Moon or
that of a planet is measured by the formula (1 + cos EPS) / 2
where P is the planet or the Moon. Since ES is almost
Fig. 29
parallel to PS (Fig. 29) ÊPS may be taken to be nearly
equal to P̂ES which is the elogation of the planet or the
Moon so that phase = (1 - cos EPS) / 2 approximately. So

213
in modern astronomy also the phase is measured through
the elongation. But the maximum phase in modern
astronomy is taken to be unity as could be seen from the
formula, for, when EPŜ = 180°, the phase = 1. Thus
the phase multiplied by 15 gives approximately the tithi.
We shall have occasion to deal with this topic later.
(3) Suppose ☾ − ☉ = E°. The number of the
tithis elapsed is equal to the quotient in E / 12. Take the
remainder r°. It means during the current tithi which
has a duration of 12°, r° have elapsed. Let the daily
motions of the Moon and the Sun be m and s so that the
Moon overtakes the Sun by m − s (expressed in minutes
for convenience) during 60 nādīs. The elapsed time of
the current tithi in nādīs is given by (r × 60 × 60) / (m − s). But
r × 60 × 60 = Seconds of arc of the remainder so that
it is said “गतैष्यविलिप्तिकाः”. If it be required to find how
many nādīs the next tithi lasts, (12−r)° or (12−r) × 60′
is to be gained by the Moon over the Sun. So the time in
Nādīs = ((12 − r) × 60 × 60) / (m − s) = एष्यविलिप्तिकाः / (m − s) .
(4) A lunation is again divided into 60 Karaṇas
and so 6° of increase in elongation correspond to a Karaṇa.
These Karaṇas are eleven in number, out of which 4 are
fixed to occur during the latter half of Kṛṣṇa Chautùrdasī,
during the two halves of Amāvāsyā and the first half of
the Sukla pratipat. Their names are Sakuni, Chatuṣpāt,
Nāgava, and Kimstughna. So there remain 56 halves of
tithis during the lunation during which the remaining
seven Karaṇas, Known as Bava, Bālava etc. rotate eight
times. Thus the first half of the duration of any tithi is
covered by one Karaṇa and the latter by another. The
computations of Karaṇas proceeds as with respect to tithis

214
but dividing the elongation by 6, we are asked to count
K — 1, (where K is the quotient) beginning with Bava
because the first half of Sukla pratipat is covered by the
fixed Karaṇa Kimstughna. The computation of the elapsed
as well as the remaining nādīkas of a particular Karaṇa,
it proceeds on the same lines as that of a tithi.
(5) The Nakṣatra in which a planet or the Moon
is situated is then found. The zodiac is divided into 27
equal divisions beginning with its zero point and each
division is named after the brilliant star of that division.
Those stars are Aświnī, Bharaṇī etc. The star occupied
by the Moon has a special significance in the Hindu
calendar, it being spoken of that every day is presided over
by a nakṣatra. This happens so because the Moon’s
sidereal period is approximately 27 days.
(6) To compute the Nakṣatra in which the planet
or Moon is, take its longitude in minutes of arc λ; divide
by 800, since each star division consists of 360° / 27 = (360 × 60) / 27
minutes = 800'. The quotient gives the elapsed nakṣa-
tras. To get the elapsed nādikās of the current nakṣatra
or the remaining, let the remainder be r'. Then the
proportion is ‘If during the day of 60 nādīs, the planet
or the Moon goes p minutes what time does it take to
cover r' or 800 — r'’. The answer is
(r' × 60) / p' or ((800 — r') × 60) / p' = गतैष्यविलिप्तिकाः / p' .
(7) Regarding yogas, let the longitudes of the Sun
and the Moon be ☉ and λ in minutes of arc; let their daily
motions be s and m in minutes. If the sum of the longi-
tudes is 800', we say the first yoga named Viṣkambha is
over, if the sum is 1600', the second Yoga, named prīti
has elapsed. Thus going on if the sum is 360°, we say the
27 yogas have elapsed and the first again begins. Since
the sum of the daily motions of the Sun and the Moon

215
are on the average 59'—8''+790'—35''=850', to cover
one Yoga, they take roughly one day since the duration
of a yoga is of 800'. To get the number of elapsed yogas,
divide (⊙+M)' where M is the longitude of the Moon by
(s+m). To get the elapsed nādīs which are given by the
remainder r' or the remaining nādīs of the current yoga
which are given by 800; the proportion is ‘If by s+m
gain in the sum of the longitudes we have 60 nādīs, what
time is indicated by r' or 800—r'?’. The answer is
(r' × 60)/(m + s) or ((800 — r)' × 60)/(m + s) = गतैष्यविलिप्तिकाः/(m + s) .
By the word गतैष्यविलिप्तिकाः is meant therefore the number
of seconds of arc as many as the remainder r or (800—r)
is in minutes or what is the same the remainder or 800—r
converted into seconds.
(8) The tithi, karaṇa, nakṣatra of the Moon and
yoga constitute four of the Angas of the panchānga or the
Hindu Calendar the fifth being the week-day. All these
five are supposed to have their effects good or bad on living
beings.
Verses 68, 69. The correction what is called Nata-
karma.
The Zenith distances of the Sun and the Moon at the
end of Purṇimā or Amāvāsyā at the time of lunar or solar
eclipse, being expressed in nādīs, are multiplied by 6 to get
the degrees. Let their H sine be got from the short table
of H sines. Multiply it by the equations of centre of the
Sun and the Moon. Divide by 4920, and 4361 respectively.
If the Sun be in the Eastern hemisphere, let the result
pertaining to the Sun be subtracted from his position ; if
in the Western, let it be added to his position. If the
Moon be in the Eastern hemisphere and if his equation
of centre be negative let the result be added to his position;
if the equation of centre be positive, let the result be sub-
tracted from his position in either of the hemispheres.

216
Again from these positions, let the tithi be computed and
again let the above process be carried out until a constant
time is arrived at for conjunction or opposition.
Comm. (1) The above procedure is accepted by
Bhaskara as Āgama enunciated by Brahmagupta and
reiterated by Chaturveda as giving results that accorded
with observation. We shall see that the correction known
in modern astronomy as 'correction due to astronomical
refraction' is indicated here, though it was not stated
explicitly.
In fact what was stated by Brahmagupta was that
the periphery of the Manda epicycle given as 13⅔° for the
Sun and as 31-36 for the Moon hold good only on the
meridian but the periphery of the Sun is to be increased
or decreased by 20' according as the equation of centre is
negative and the Sun is the Eastern equatorial horizon,
or western equatorial horizon. If the equation of centre
be positive the reverse correction is to be effected in
the periphery i.e. for negative equation of centre.
Periphery on the Eastern equatorial horizon = 14°-0
On the meridian = 13°-40'
On the Western equatorial horizon = 13°-20'
For positive equation of centre
Periphery on the Eastern unmandala i.e.
equatorial horizon = 13°-20'
On the meridian = 13°-40'
On the Western unmandala = 14°-0
In the case of the Moon, for negative equation of
centre.
On the Eastern unmandala = 30 - 44
On the meridian = 31 - 36
On the Western unmandala = 32 - 28

."
"Include all Sanskrit shlokas, sutras, mathematical derivations, tables, numerical examples, Hindi translation, commentary, and footnotes. Prefix each line with line marker like , ."
Let's represent the fraction cleanly using standard text notation, e.g., 1/3 × 1/120 = H sin Z / 360 or similar clean text.
Wait, let's see how lines correspond to the printed page.
Let's trace every printed line:

Line 1: 217 (page number at the top)
Line 2: For positive Equation of centre.
Line 3: On the Eastern unmandala = 30 - 44
Line 4: On the meridian = 31 - 36
Line 5: On the Western unmandala = 30 - 44
Line 6: In between the meridian and the unmandala, pro-
Line 7: portion is to be used. If by H sine Z equal to R, there
Line 8: is a difference of 20' in the periphery of the Sun, what
Line 9: will it be for an arbitrary H sin Z? The result is
Line 10: `H sin Z × 1/3 × 1/120

218
(3) Consider for the Sun first for negative
equation of centre.
(a) On the east, the negative equation being
increased, elevation is effected.
(b) On the west, the negative equation of centre
being rendered less, elevation is effected.
(c) For positive equation of centre, on the east it
being lessened, again elevation is effected.
(d) For +ve equation of centre on the Western
side it being increased again it is elevated.
Thus with respect to the Sun, the stipulated correction
effects elevation in all the cases which accords with the
effect of the modern refraction.
Then let us consider the case of the Moon.
(e) In the case of negative equation of centre, it
being lessened in the East, the effect is
depression.
(f) And being increased in the west, the effect
is depression.
(g) In the case of positive equation of centre, it
being reduced in the east, elevation is
effected.
(h) And in the west, it being reduced, elevation
is effected.
Thus in the case of the Moon, the phenomenon is
recorded as depression in the case of negative equation of
centre. Out of these two cases again the equation of
centre being lessened is truly desirable as the Hindu
equation of centre is in excess of the true value. So it
need not be interpreted as depression. Regarding the
other case, the error might have been due to the fact that
a lesser parallax being taken, whose effect is to depress

219
the celestial body, depression might have been noticed
during the course of an eclipse wherein conjunction or
opposition had to be belated; or again the greater equation
of centre as was postulated for the Sun, than what it
should be when his equation of centre was negative might
have depressed the Sun, so that the Moon had to be
depressed to arrive at the correct moment of conjunction
or opposition. Thus this correction of Natakarma which
was accepted by Bhāskara on the reported Āgama of
Brahmagupta and also on the right endorsement of
Chaturveda, must have been in fact no other than the
effect of the phenomenon of astronomical refraction, and
what further strengthens this observation is the prescri-
ption of H sin Z which is proportional tan Z. Also the
modern formula being A tan Z where A = 58″ approxi-
mately, when Z is sufficiently large, the magnitudes given
by Brahmagupta are of the same order as that of the
moderns. This correction of Natakarma really reflects
much credit on the ancient Hindu observations.
Verse 70. Computing the planetary position for a
given moment.
The daily motion of the planet being multiplied by
the time that has elapsed or that is to elapse at which
the planetary position is to be found, and divided by 60,
and the result being substracted from or added to the
planetary position found, will render the position hold
good for the moment in question. The Sun and the Moon
will become by this process of what is called तात्कालिकीकरण
equal up to minutes for the moment of conjunction or
opposition. For opposition only the Rāśis differ whereas
the degrees, minutes and seconds in their positions will
be equal whereas for opposition, the positions are equal
in all respects ie. Rāśis, degrees, minutes and seconds
too.
Comm. The meaning is clear.

220
Verses 71 to 75. Obtaining what are called Sukṣma-
nakṣatras.
The computation of the nakṣatras done as pres-
cribed before, is only approximate. Now I shall give
the method of obtaining what are called Sukṣma-
nakṣatras as prescribed by the Ṛiṣis that are required to
note auspicious occasions regarding marriages, journeys
etc. people who knew about it, told that the six stars
Viśākha, Punarvasu, Rohiṇī, and the three Uttaras or
Uttaraphālgunī, Uttarāṣādhā, Uttarabhadrā have the
duration of one and half stars ie. 3/2 × 790′ — 35″ =
1185′ — 52″. The six stars Āslesha, Ārdrā, Swāti,
Bharaṇī, Jyeshṭhā and Śatabhishak have half the duration
of a star ie. 395′ — 17″. The remaining 15 alone have
one nakṣatra duration ie. 790′ — 35″. A star's duration
is the mean daily motion of the Moon ie. 790′ — 35″. The
sum total of all the above 27 stars being subtracted from
360°, give the duration of the star what is called Abhijit
which occurs after Uttarāṣādha and before Śravaṇa. To
obtain the star in which a planet is situated, convert its
longitude in minutes of arc and substract the durations
of the stars from Aświni as many as could be substracted .
The number of stars whose durations are thus substracted
are deemed to have elapsed. The remainder is called the
gata or elapsed portion of the current star and the
difference of this gata and the duration of the current
nakṣatra is called the Ēṣya, ie. unelapsed portion. To
obtain the elapsed time or the unelapsed time of the
current star the gata or the ēṣya is to be multiplied by
60, and divided by the daily motion of the planet
concerned the result being in nādīs.
Comm. One line in the verse 72 is evidently missing
which should name Rohiṇī and the three Uttaras. We
are able to know them from Bhāskara's commentary
as well as from Brahmagupta and Śrīpati. In the course
of the commentary Bhāskara reiterates what was stated

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

222
touches the previous division. In other words it is the
interval between the first contact of the disc with the
succeeding division and the last contact with the previous
division.
(2) In the case of the Sun the duration of the Sans-
krānti is equal to (32' ½) / (59 — 2) of a day taking the maximum
magnitude of the disc and the minimum daily motion
approximately = 65 / (2 × 57) × 60 nāḍīs = 650 / 19 = 34 — 12
nāḍīs approximately or more accurately (32 ²¹/₄₀) / (56 ¹¹/₁₂)
= 1301 / 40 × 12 / 683 = 3903 / 6830 of a day
= 3903 / 683 × 6 nāḍīs = 23418 / 683 = 34 — 17 nāḍikās.
Taking liberal boundaries, the वृद्धकारिका or the elders
saying is विंशतिः पूर्वे, विंशतिः परे ie. 40 nāḍikās on the whole.
Here ends the Spaṣṭāshikāra.

ॐ
THE TRIPRAŚNĀDHIKĀRA
Verse 1. The purport of this chapter.
Pandits say that this is the science of time in as
much as, herein there is described the method of knowing
the direction and the point of space (where a celestial body
is situated) given the time. Hence I expound that
chapter, which gives that knowledge and which abounds in
very important statements, which forms the quintessence
of the science of astronomy.
Comm. This chapter is called Tripraśnādhikāra,
since this deals with the three questions pertaining to the
direction and the point of space of a celestial body for
a given time ie. dealing with Deśa, Dik and Kāla. In
this chapter we come across the Hindu methods of
spherical trigonometry, and gnomonics or Śaṅkuvedha
or observations with the help of a gnomon. Also we find
herein a usage of what is called ‘Golayantra’ or the
armillary sphere, which helped the Hindu astronomers to
solve all diurnal problems. We find herein Bhāskara
excelling himself. This chapter abounds in a good number
of technical terms and without a knowledge of this
chapter, no one could call himself a Hindu astronomer.
Verses 2-4. To compute what is called lagna given
the time.
The lagna or the ascendant as it is called or the point
of intersection of the ecliptic with the horizon at a given
point of time is obtained as follows. Obtain the Sāyana
longitude of the Sun at the point of time at which it is
required to find the lagna. Supposing the Sun is in the
rth degree of a particular Rāśi, the number of asus which

224
give the rising time of the arc of (30 — r)° of that Rāśi
are called the Bhogyāsus, or the asus which are taken by
the remainder of the Rāśi to rise at the place. They are
equal to. ((30 — r) × T) / 30 where T gives the asus of the
rising time of that Rāśi. The Bhuktāsus on the other
hand are the asus which pertain to the rising time of the
arc of the first r° of that Rāśis, which are therefore
equal to (r × 𝒯) / 30 ; from the given time substract the
Bhogyāsus formulated above; then substract also the
rising times of as many subsequent Rāśis as could be
substracted. Let 'R' be the remainder of the time
given. If t be the rising time in asus of the next Rāśi,
(R × 30°) / t gives the number of degrees by which the lagna
has advanced in the next Rāśi. These degrees added to
the previous Rāśis beginning from ♈ the equinoctial point
give the Sāyana or the modern longitude of the lagna.
From this Sāyana longitude if we substract the Ayanamsa,
we have the Nirayana or the Hindu longitude measured
from the Hindu Zero-point of the ecliptic. If, however,
the given time after Sun-rise expressed in asus say 'a'
falls short of the Bhogyāsus defined above, then, (a × 30) / 𝒯
where 𝒯 is the rising time in asus of the Rāśi in which
the Sun is situated, added to the longitude of the Sun,
gives the Sāyana longitude of the lagna.
Comm. The substance of these verses, though appears
to be simple, yet is complicated which can be better under-
stood with the help of a figure (Ref. fig. 30).
Let SEN be the horizon, ♈ER the celestial equator
and ♈AL the ecliptic where L is the point of lagna.
Required to find ♈L the Sāyana longitude of L from
which if Ayanamsa be substracted we get the Hindu