I was looking for the list of trusted central directory servers that tor uses to bootstrap its list of tor network nodes. It's to be found in add_default_trusted_dirservers in or/config.c and is as follows

static void
add_default_trusted_dirservers(void)
{
  int i;
  const char *dirservers[] = {
    "moria1 v1 18.244.0.188:9031 "
      "FFCB 46DB 1339 DA84 674C 70D7 CB58 6434 C437 0441",
    "moria2 v1 18.244.0.114:80 "
      "719B E45D E224 B607 C537 07D0 E214 3E2D 423E 74CF",
    "tor26 v1 86.59.21.38:80 "
      "847B 1F85 0344 D787 6491 A548 92F9 0493 4E4E B85D",
    "lefkada 140.247.60.64:80 "
      "38D4 F5FC F7B1 0232 28B8 95EA 56ED E7D5 CCDC AF32",
    "dizum 194.109.206.212:80 "
      "7EA6 EAD6 FD83 083C 538F 4403 8BBF A077 587D D755",
    NULL
  };
  for (i=0; dirservers[i]; i++)
    parse_dir_server_line(dirservers[i], 0);
}

The list can also be found by running tor --log debug