21 beginning of mean Caitra and the beginning of the mean solar year, and constitute the so called "subtractive." SIMPLIFIED RULES The definition of the so called grahatanu for the Moon, Mars, Jupiter, and Saturn : 29. The number of years elapsed (since the commencement of Kaliyuga) multiplied by 360 is always called grahatanu. The (mean) longitudes (reduced to degrees) of the planets (Sun, Mercury, and Venus) together with the grahatanu are called dhruvaka by the learned. The term grahatanu denotes the number of mean solar days elapsed at the beginning of the mean solar year since the beginning of Kaliyuga. This grahatanu, as remarks the commentator Parameśvara, is really a part of the grahatanu. The dhruvaka (i.e., complete grahatanu) denotes the number of mean solar days elapsed on the given lunar day since the beginning of Kaliyuga. The above dhruvaka, or grahatanu, is defined for the Moon, Mars, Jupiter, and Saturn only; that for the Sun, Mercury, and Venus is defined in the next stanza. The grahatanu for the Sun, Mercury, and Venus : 30. Diminish the (lunar) days elapsed since the beginning of Caitra by the corresponding complete omitted lunar days (obtained in the second half of stanza 26) and divide (the difference) by seven: the remainder (of the division) counted with the first day of Caitra is said to give the (current) day. From that, the "subtractive" for the year (obtained in stanzas 27-28) should also be subtracted. (But it must be remembered that) the minuend of this subtraction is the difference of the previous subtraction and not the other (i.e., not the remainder of the division). (The remainder obtained by subtracting the "subtrac- tive" is the grahatanu for the Sun, Mercury, and Venus. It denotes the number of mean civil days elapsed since the beginning of the mean solar year). The number of mean civil days elapsed since the beginning of the mean solar year is generally known as laghvahargana ("smaller ahargana").
