पञ्चसिद्धान्तिका (आचार्य वराहमिहिर - सूर्य, रोमक, पौलिश, वासिष्ठ एवं पितामह सिद्धान्त)

154 PAÑCASIDDHĀNTIKĀ VI.2 idea. NP insert vi to get the reading ravi-vivarāt but leave the other errors untouched or making unwarranted emendations. [चन्द्रग्रहणसम्भवः] राहोः स‘षट्कृति’कलां हित्वांशं तच्छाशाङ्कविवरांशैः । ग्रहणं त्रयोदशान्तः पञ्चदशान्तस्तमस्तस्य ॥ २ ॥ Probability of an eclipse 2. Deduct one degree and thirty-six minutes from Rāhu's Head or Tail (whichever is near the Moon) and find the interval in degrees between that and the Moon (at full moon found above). If it is less than thirteen, a lunar eclipse will occur then. If it is less than fifteen, (and above thirteen), there will only be a slight darkening. The following is the explanation: At the moment when the distance between the centres of the Moon and the Shadow circle is equal to the sum of their semi-diameters there is the first contact or the last contact of the eclipse, because the rims just touch each other then. see Fig. 1a, below. [Diagram: Moon's orbit, R, Ecliptic, S, M] Fig. VI. 1-a. The centre of the Shadow is always six rāśis distant from the Sun. At full moon (i.e. the end of the tithi) the Moon projected on the ecliptic (i.e. the longitude of the Moon) is 6 rāśis distant from the Sun, as we have already said. Therefore the centre of the Shadow also is there. But the actual Moon 2a. B. सषट्कृतिकलां (B2. वांशं, B3. चाशं०) b. A2. हिचांशं (A1. हित्वांशं) ; B. हिषारांतष्टांशक d. A.B. ०दशान्तःस्तमस्तस्य (B. ०न्तःस०)