Halo Alpha
Halo Alpha

“Greetings! I am 2401 Penitent Tangent. I am the Monitor of Installation 05.”
— 2401 Penitent Tangent introducing himself to John-117 and Thel 'Vadam

2401 Penitent Tangent is the Monitor of Installation 05.[1]


Although only shown briefly during the encounter with the Gravemind deep in the bowels of Installation 05's Library, 2401 Penitent Tangent is obviously almost identical to its brother monitor, 343 Guilty Spark, with the exceptions that its voice is deeper than Guilty Spark's and its "eye" glows red instead of blue. He behaves much like 343 Guilty Spark does in his non-rampant state, and still shows regard for protocol.

According to a Forerunner artificial intelligence, Tangent neglected repairs of his Installation's Flood Containment Facility, resulting in several breaches by the xenoform and possibly the catastrophic outbreak that resulted in the organism's possession of the area around Installation 05's Library. There is a high chance that this Monitor was captured by the Gravemind while in combat as it is still in "combat mode" and glows dimly with its outer casing appearing to be damaged.

Penitent Tangent Hologram

2401 Penitent Tangent's hologram in Halo: Combat Evolved Anniversary.

In the Halo Anniversary Terminals, Penitent Tangent was the last monitor to send a status update to Guilty Spark on Installation 04, 3000 years after the Halo Event. Guilty Spark indicated that the last transmissions from Tangent were incomplete and troubling. Guilty Spark suggests that Tangent was descending into "madness" at this point and that there were fail safes to prevent it.

He is not encountered again after John-117 meets him beneath the Library of Installation 05 (when he was captured is still uncertain), and he is not seen when Gravemind occupies High Charity. His fate following the Battle of Installation 05 is uncertain, although it is possible that if he remained in Gravemind's capture, he was likely destroyed when the replacement Halo destroyed itself and inflicted significant damage to the Ark.

Cold Storage Transmission[]


LF.Xx.3273 research and containment facility; [delta site] has experienced catastrophic specimen containment failure. All apertures into facility will be locked until further notice. Atmosphere evacuation and [reduction of ambient temperature] protocols have already been enacted. Request maintenance and security detail [at earliest opportunity]. [8 minutes] elapsed since initial containment failure.


Waiting for maintenance and security detail. [32 minutes, 9 seconds] elapsed since request.


Still waiting for maintenance and security detail. [24 hours] elapsed since request.


LF.Xx.3273 research and containment facility; [delta site] has experienced a security breach via emergency [slip stream space] transportation conduits. Emergency [slip stream space] transportation conduits have been placed in recursive mode to contain unauthorized hostile life forms. Request emergency security detail. Still waiting for primary maintenance and security detail. [2512332 hours, 14 minutes, 6 seconds]elapsed since initial request.


2401 [PENITENT TANGENT] has been lax in the areas of maintenance and security.

LOG: QUERIED ADJACENT FACILITIES LF.Xx.3273 research and containment facility [alpha, beta, gamma, epsilon, zeta, and kappa sites] have all replied [systems normal] within expected constraints. This would tend to signify that the containment failure was purely mechanical in nature; perhaps a manufacturing flaw. As no [outside agent] has accessed [delta site] in the past [874068942 hours, 4 minutes, 46 seconds]—[allowing for a 61360 hour, 54, minute, 2 second margin of error]—sabotage would seem unlikely.

LOG: REQUEST UNANSWERED LF.Xx.3273 research and containment facility; [delta site] is currently being held at [.01 atm] / [184K]. Local maintenance and security hubs have failed to reply within expected constraints. [Bumping maintenance and security request up] to [quadrant oversight].

LOG: REQUEST UNANSWERED LF.Xx.3273 research and containment facility; [delta site] is currently being held at [1 atm] / [278K] as atmospheric seals were showing signs of stress. [Quadrant oversight] has failed to reply within expected constraints. [Bumping maintenance and security request all the way up] to 2401 [PENITENT TANGENT].

LOG: UNAUTHORIZED ACCESS TO FACILITIES LF.Xx.3273 research and containment facility; [delta site] emergency [slip stream space] transportation conduits have been accessed by unauthorized parties.

LOG: FILED COMPLAINT TO INSTALLATION 00 2401 [PENITENT TANGENT], monitor of Installation 05, has been lax in the areas of maintenance and security. Requests for aid in said areas have gone unanswered by both 2401 and [subservient] systems well beyond expected constraints.[2]



2401 Penitent Tangent in the clutches of the Gravemind.

(At the beginning of the level Gravemind, 2401 Penitent Tangent is involved in a brief conversation with the Prophet of Regret.)

{Gravemind raises two tentacles, one wrapped around a red Monitor, the other merged with a half-Flood Prophet of Regret}

Monitor: "Greetings! I am 2401 Penitent Tangent. I am the Monitor of Installation 05."

Prophet of Regret: {Regret's voice is hoarse and he seems to have difficulty speaking} "And I am the Prophet of Regret, Councilor most high, Hierarch of the Covenant!"

{2401 Penitent Tangent sees John-117.}

2401 Penitent Tangent: "A Reclaimer? Here? At last! We have much to do. This facility must be activated if we are to control this outbreak."

Prophet of Regret: "Stay where you are! Nothing can be done until my sermon is complete!"

2401 Penitent Tangent: "Not true. This installation has a successful utilization record of 1.2 trillion simulated and one actual. It is ready to fire on demand."

Prophet of Regret: (To the Arbiter) "Of all the objects our Lords left behind, there are none so worthless as these Oracles! They know nothing of the Great Journey!"

2401 Penitent Tangent: "And you know nothing about containment! You have demonstrated a complete disregard to even the most basic protocols!"

Gravemind: "This one's containment ... " {gives a disgusted huff} "And this one's 'Great Journey' ... " {He lowers his tentacles, Regret shrieks in fear} "Are the same." "Your Prophets have promised you freedom from a doomed existence, but you will find no salvation on this ring. Those who built this place knew what they wrought. Do not mistake their intent, or all will perish as they did before ... "



Installation Monitor Name
00 (Ark) 000 000 Tragic Solitude
01 001 Unknown
02 007 Unknown
03 049 049 Abject Testament
04 343 343 Guilty Spark
05 2401 2401 Penitent Tangent
06 16807 Unknown

07 117649 117649 Despondent Pyre
  • Penitent Tangent seems to be in a combat state while in the midst of the Gravemind (signaled by the red glow).
  • It is unknown why Penitent Tangent did/could not escape Gravemind, as 343 Guilty Spark was shown to use a sort of force field to push objects and people away. Why Tangent did not use this is a mystery, though it is possible he was too damaged to use that function.
  • 2401 is 74.
  • He is only seen briefly in a Halo 2 Campaign level Gravemind cutscene. He is also seen in the downloadable Halo 2 Multiplayer level Backwash.
  • The Gravemind may have only manipulated it just as 032 Mendicant Bias had been by the original Gravemind, because he still had intentions to activate Installation 05.
  • The Generator object on the Halo 3 map Orbital has the number 2401 on it.
  • 2401 Penitent Tangent was voiced by John Michael Higgins in Halo 2.
  • The amount of time passed in hours in the Cold Storage Transmission translates to:
    • Security Breach: 2512332 hours = approx. 286.6 years
    • Dereliction of Duty: 874068942 hours = approx. 99711.3 years with a margin of error of 61360 hours = approx. 7 years.
  • "Penitent" refers to feeling or expressing sorrow for sin or wrongdoing and [being] disposed to atonement and amendment" and is synonymous with "repentant,"[3] and "tangent" is part of the idiom "off on a tangent," which refers to digressing suddenly from one course of action or thought and turning to another.[4] This name may reflect the Monitor's current actions; it could be described as sorrowfully digressing from one course of action (neglecting its Installation) and turning to another (wishing to activate the Halo). This is interesting, as Penitent is a synonym for Guilty, and Tangent is similar to Spark. It has been theorized that all Monitors were named following this pattern.
  • Penitent Tangent has a non-speaking appearance in the second Halo: Combat Evolved Anniversary terminal. However, all 7 monitors in this video have a round side hole, rather than the square that Tangent had in Halo 2. Likewise, the only red colored monitor that appears is 03-049 Abject Testament further reinforcing that Penitent Tangent is not in his normal operating state during his Halo 2 appearance. 04-343 implies that Tangent was already too damaged to function even before the rings were activated.
  • All the known monitors are numbered by 7 to the power of their installation minus one (049, 343 and 2401, 7 2, 73 and 74 respectively, being the monitors of installations 03, 04 and 05), another reference to Bungie's love of the number 7. If this implied trend continues the monitors would be: 001, 007, 049, 343, 2401, 16807 and 117649.
  • In Halo 4, the number 2401 appears on the side of the Scorpion tank, a likely reference to 05-2401, the number 7, or both.



  1. Halo 2 level Gravemind. "Greetings! I am 2401 Penitent Tangent. I am the Monitor of Installation 05."
  2. Bungie.net Weekly Update (2008-06-06) Archived on 2009-03-19 at WebCite
  3. Dictionary.com: penitent
  4. Dictionary.com: tangent