The computation is a function field sieve algorithm for the field GF( 3^(6*97) ). This field is of interest for pairing-based cryptography, as there is a supersingular embedding degree 6 curve over GF( 3^97 ) with near-prime order.
This builds on previous work by these groups, for example see:
Takuya Hayashi, Naoyuki Shinohara, Lihua Wang, Shin’ichiro Matsuo, Masaaki Shirase, Tsuyoshi Takagi: Solving a 676-Bit Discrete Logarithm Problem in GF(3^(6n)). IEICE Transactions 95-A(1): 204-212 (2012) , and lso their paper at Public Key Cryptography 2010 (Springer LNCS 6056) 351-367.
It is a very good result — well done!
— Steven Galbraith