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

Introduction liii
mihira distinctly mentions the fact that in his time
the summer solstice took place at the beginning of
Cancer is a complete answer to the question we
have been discussing.
Dr. Thibaut, the learned editor of the
Panchasidhantika, however, finds difficulty in
accepting Saka 427, as the date of the composition
of the work. As far as I can gather from his
introduction to the work, his main objection lies in
a statement of Amraja, quoted by Bhau-Daji, that
“Varaha-mihira Acharya went to heaven in the
509th year of the Saka kala, i.e. A.D. 587”. For if
Varaha be supposed to have written the work in
Saka 427, he must have lived to the good old age
of eighty-two years after the composition; and
supposing him to have written it at the age of
twenty-years, he must have seen 102 summers.
Seeing that Varaha lived long enough to write
a very large number of works, there is nothing in
the statement intrinsically impossible. On the other
hand, if the Saka year were not the epoch of his
Karana, he defeated his own purpose. In deed, the
idea of a Karana-writer using a date borrowed from
some older Siddhanta, as has been supposed in this
case, and thus representing a time other than that
for which the work is written, is to say the least,
self-contradictory. Then again as has been pointed
out by Pandit Dwivedi, there is absolutely no proof
of the validity of Amraja’s assertion. Dr. Thibaut
admits that if Saka 427 be taken as the epoch of
Varaha’s work, several facts, not otherwise
explainable, become easy of explanation. All those
considerations, together with tradition about
Varaha’s time point to the conclusion we have
already arrived at by discussing ayanamsa.