def is_valid_transaction_hash(tx_hash):
    """Determines if the provided string is a valid Stellar transaction hash.

    :param str tx_hash: transaction hash to check

    :return: True if this is a correct transaction hash
    :rtype: boolean
    """
    if len(tx_hash) != 64:
        return False

    try:
        int(tx_hash, 16)
        return True
    except:
        return False