ब्राह्मस्फुटसिद्धान्त (ब्रह्मगुप्त - शून्य, कुट्टक, बीजगणित एवं सम्पूर्ण २१ अध्याय सान्वय सटीक)

112 INDIAN LUNI-SOLAR ASTRONOMY Greek value=5°0'. Modern mean value=5°8'43".427 (Brown) This discrepancy confirms the conclusion, that the observa- tion of the Moon was restricted to the time when she was near a node, either at solar or lunar eclipses, where a small error of observation magnified itself into about half a degree. We now turn to the parallaxes of the Sun and the Moon :-

	Sun's Mean Hor. Parallax	Moon's mean Hor. Parallax
Āryabhaṭīya	3'55".62	52'30"
Kaṇḍakhādyaka	3'56"5.	52'42".3
Ptolemy	2'51"	53'34"
Modern values	0'8".806	57'2".79
As to the Sun's horizontal parallax, the ancients were of
course totally wrong, but in respect to that of the Moon their
values were fairly approximate.
We next consider the angular semi-diameters of the Sun
and the Moon. These are :-
	Moon's Mean Semi-diameter	Sun's Mean Semidiameter
:---	:---	:---
Āryabhaṭīya	15'45"	16'29".4
Khaṇḍakhādyaka (Brāhmasphuṭa-siddhānta)	16'0".22	16'15"
Ptolemy	17'40"	15'40"
Modern values	15'33".60	16'1".8
Here also the Indian values are more accurate than the
Greek values.
Moon's Equations. The First Equation.
It remains now to consider the Moon's equations in ancient
Indian astronomy. As has been pointed out before, obser-