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

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actual computation, we should not take the Moon as such.
The pāta named Vaidhṛti occurs when in the same Fig.
124, SL=M¹N¹. Herein both the Sun and Moon are in
the same Ayana namely Uttarāyaṇa but in opposite goḷas.
If we assume the Moon to be moving on the ecliptic,
Vyatīpāta occurs when the sum of the tropical longitudes
of the Sun and Moon equals 180° and Vaidhṛti occurs
when the sum of those longitudes is equal to 360.
Verse 2. Definitions of Goḷa-Sandhi and Ayana-
Sandhi with respect to the Sun.
When the tropical longitude of the Sun ie. his
longitude measured from ♈ along the ecliptic is equal to
0° or 180°, then he is said to be at his goḷa Sandhi. In
other words, when the Sun who moves along the ecliptic
comes to the celestial equator, he will be at his Goḷa
sandhi. Similarly when his longitude is 90° or 270°, he is
said to be at the his Ayana-Sandhi.
Comm. This means that when the Sun is about to
pass from the Dakṣiṇa goḷa to the uttaragoḷa or from the
uttaragoḷa to the Dakṣiṇagoḷa he is said to be at a Goḷa
Sandhi. Similarly when he is about to go south or when
he is about to go north, he is said to be at Ayana Sandhi.
The word 'Sandhi' means junction. Thus the points ♈ and
♎ (Libra) are said to be goḷa Sandhis whereas the points
denoting Cancer and Capricorn are Ayana-Sandhis. Since
in Bhāskara's time the Ayanamsas were 11°, ie. the point
♈ was behind the zero point of the Hindu Zodiac by 11°,
therefore Bhāskara gives the Goḷa Sandhis as the points
having longitudes 349° and 169° respectively. Similarly
the Ayana Sandhis were the points having longitudes 79°
and 259° respectively.
Bhāskara gives the method of locating these goḷa
Sandhis or Ayana Sandhis as follows. Erect a gnomon