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

187 ecliptic successively each of 30°, we have what are called Sāyana Rasis or Rasis taking the Ayanāṁsa into consi- deration or in other words measuring from r. On the other hand successive arcs each of 30° measured from the zero point of the Hindu Zodiac, constitute what are called the Nirayana Rāśis. The words Meṣa, Vṛṣabha etc. signifying the shapes of the constellations apply strictly to the Nirayana Rāśis. But nonetheless, by the conven- tion what is called Upachāra, we name the Sāyana Rāśis also by the same names. In as much as the zero-points of the Hindu Zodiacs is ahead of the modern zero-point by an arc which is the arc of Ayanamsa or accumulated pre- cession, the words Sāyana and Nirayana came into vogue. Once upon a time approximately in Varāha’s time or rather 499 A. D, the two zero-points coincided and then the Sāyana and Nirayana Rāśis were the same. Gradually on account of the phenomenon of precession r preceded, and today the distance between r and the Hindu zero- point is about 20°–30′. Of late, there has been a big controversy as to what exactly the arc is and the Calendar reform committee has adopted a value far more than what could be justified. The present author opines, that we have no right to set aside a statement of no less an astro- nomer than Varāhamihira who stated explicity ‘आश्लेषार्धात् दक्षिणमुत्तरमयनं रखेर्धनिष्ठाद्यम् , नूनं कदाचिदासीत् येनोक्तंपूर्वशास्त्रेषु, साम्प्रतमयनं सवितुः कर्कटकाद्यं मृगादितश्चाऽन्यत् उक्ताभावो विकृतिः प्रत्यक्षपरीक्षणव्यक्तिः” i.e. True it is that once upon a time, the Sun began his southern journey when he was mid-way the constellation of Asleṣa and his northern when he was at the beginning of Dhaniṣtha, because it was stated in ancient texts. (The allusion is to Vedāṅga Jyotiṣa where it was stated as such); but now the southern journey of the Sun begins from the point marking ¾ of the con- stellation of punarvasu which is the beginning point of the Karkaṭa Rāśi and his norther from the beginning of Makara i.e. from the point marking ¼th of the constellation of Uttarāṣādha; there has been a change from what was