gap> gamma:=HAP_CongruenceSubgroupGamma0(39);;
gap> p:=2;;N:=1;;h:=HeckeOperator(gamma,p,N);;
gap> AbelianInvariants(Source(h));
[ 0, 0, 0, 0, 0, 0, 0, 0, 0 ]

gap> A:=HomomorphismAsMatrix(h);;
gap> Display(A);
[ [  -4,   2,   4,   4,  -3,   0,   3,   3,  -3 ],
  [  -4,  -2,   6,   4,   1,   0,   1,   1,  -1 ],
  [  -3,   1,   3,   4,   0,   0,   1,   1,  -1 ],
  [  -3,   1,   4,   2,  -4,   2,   4,   4,  -4 ],
  [  -5,  -1,   7,   4,   2,   0,  -1,  -1,   1 ],
  [  -7,  -3,   6,   6,   0,   2,   2,   2,  -2 ],
  [  -1,   7,   2,  -4,  -5,   2,   5,  -1,   1 ],
  [  -2,  -2,   4,   4,   0,   0,  -4,   2,   4 ],
  [   0,   4,   1,  -4,  -5,   2,   2,   2,   4 ] ]
gap> Eigenvalues(Rationals,A);
[ 6, -2 ]
