This appears to be EMSA-PKCS1-v1_5 as described in RFC 3447, which means that after removing the header and padding, you have a DER encoding of an AlgorithmIdentifier
followed by the hash value itself.
From the RFC:
For the six hash functions mentioned in Appendix B.1, the DER encoding T of the
DigestInfo
value is equal to the following:[...]
SHA-256:
(0x)30 31 30 0d 06 09 60 86 48 01 65 03 04 02 01 05 00 04 20 || H.
So in your example, the hash value is the SHA-256 hash starting 77511bf4d7...
.