सिद्धान्तदर्पण (महामहोपाध्याय सामन्त चन्द्रशेखर सिंह - नग्न-नेत्र खगोल वेध एवं गणित महाकोश)

Introduction il
wrote his work in Saka 854,¹ and the precessional
rate assigned is 59".9 in a year. We also learn from
Dwivedi's Ganaka-tarangini that according to
Munjala, Saka 434 was without ayanamsa. Now
from 434 to 854 Saka, there were 420 years, during
which at the rate of 59".9 per year, the ayanamsa
had amounted to 6°59'18". However erroneous the
rate given by Munjala may be it will not be wrong
if we take 6°59'18" (say 7') as the ayanamsa in Saka
854. We know, however, that the rate of precession
could not have been greater than 58".68 per year.
Accordingly, the ayanamsa obtained above carries
us back through 429 years from Saka 854, the date
of Mujala's work. In other words, we find that
according to Munjala's data Saka 425 was the year
of no ayanamsa at the latest. From the ayanamsa
obtained from Munjala and that observed in Saka
1816, we note that the rate of precession amounts
to 56".8 in a year.
The next work we take is Bhasvati by
Satananda,² which is still regard as an authority for
the calculation of eclipses. He wrote his work in
Saka 1021, and according to him the rate of
precession is 60" per year. We also know that he
regarded the Saka year 450 as the year without
ayanamsa. Now, calculating the amount of

1. The date 584 in the Ganaka-tarangini seems to be a
   misprint, though it occurs thoughout the short notice of
   Munjala, excepting the passage wher Pandit Dwivedi
   quotes from Munjala, makign the date 854 Saka, adopted
   above.
2. Satananda was born in Orissa in Saka 990 (i.e., 1068 A.D.)
   and wrote the Bhasvati in Puri in Saka 1021 .(i.e., 1099
   A.D.) by adopting centmal system. Hence his name was
   Satananda as it was a pleasure to him to use centinals.