Automorphisms of the Cameron's monster with parameters (6138, 1197, 156, 252)

Let the 3-(V,K,Λ) scheme E=(X,B) be an extension of the symmetric 2-scheme. Then either E is Hadamard 3-(4Λ+4,2Λ+2,Λ) scheme, or V=(Λ+1)(Λ2+5Λ+5) and K=(Λ+1)(Λ+2), or V=496, K=40 and Λ=3. The complementary graph of a block graph of 3-(496,40,3) scheme is strongly regular with parameters (6138,1197,156,252). Let's call this complementary graph Cameron's monster. In this paper automorphisms of monster are studied.Let the 3-(V,K,Λ) scheme E=(X,B) is an extension of the symmetric 2-scheme. Then either E is Hadamard 3-(4Λ+4,2Λ+2,Λ) scheme, or V=(Λ+1)(Λ2+5Λ+5) and K=(Λ+1)(Λ+2), or V=496, K=40 and Λ=3. The complementary graph of a block graph of 3-(496,40,3) scheme is strongly regular with parameters (6138,1197,156,252). Let's call this complementary graph Cameron's monster. In this paper automorphisms of monster are studied.