In mathematics, especially functional analysis, the spectrum of a linear operator is its set of eigenvalues. The spectrum encodes a lot of qualitative information about the observable behavior of an operator.

The visible Light Spectrum can be broken up into the following seven colours (yes I insist on spelling the word correctly!):

Red, Orange, Yellow, Green, Blue, Indigo, Violet.

To get these colours one may refact light through a prism, a glass window, a glass of water (etc) all held up to the light.

This can be explained most simply with the word Rainbow.

Spectrum are the military group set up by Earth to combat the Mysterons in the hit 1960s TV show, Captain Scarlet. Contrary to popular misconception, Spectrum's central headquarters are located in London, England and are not Cloudbase. Other Spectrum posts are located in New York, USA and Paris, France, although these three Spectrum locations are never visited in the series.

Spectrum uniform

The Spectrum uniform for males consists of the following garments, which are quite typical of fashion in the late 1960s:

  • A peaked cap of dyed leather in the colour of that member's codename. The peak is rimmed with a microphone that comes down to mouth-level when in use. The cap features the Spectrum logo on the forehead.
  • A black turtleneck sweater.
  • A waistcoat in the colour of the member's codename. The shoulders of the coat hold small capsule-shaped lights that flash to signify an incoming communication.
  • Black trousers.
  • Knee-high PVC boots in the colour of the member's codename.
  • A holster containing a handgun with decoration of the same colour as the hat, waistcoat and boots.
  • Whilst flying aircraft, a helmet the same colour as the member's hat is worn with Spectrum logo on the forehead and a brown-tinted visor.

The female uniform (i.e. that of The Angels) consists of:

  • A white helmet with built-in microphone and sporting the Spectrum insignia on the forehead. The visor of the helmet has a brown tint to it.
  • A cream jacket and trousers.
  • White shoes.

Members of Spectrum

Upon joining Spectrum, each officer is given a colour as a codename. (presumably to protect identities within this elite and secret organisation) Military ranks are used that are roughly equivalent to those in the British army, but it seems that the rank of 'captain' is immediately followed by that of 'colonel'. (no majors or Lt. cols, on Cloudbase at least) Spectrum was supposed to be a large world-wide organisation with countless operatives, but the following officers make up the crew of Spectrum's air born command post, Cloudbase: (listed in approximate order of rank)

Colonel White

One of the four most-seen Spectrum officers on the show, White is the commanding officer (and seemingly oldest by quite a margin) of Cloudbase and is most often seen sitting behind his desk in Cloudbase's control centre.

Captain Black (missing)

Captain Black was a very highly-ranking Spectrum officer until his fateful leadership of the Martian exploration project, during which he was taken over by The Mysterons and made into their main representative on Earth. Black is officially listed as 'missing' by Spectrum.

Captain Blue

Originally known as 'Adam', Blue is Captain Scarlet's second partner after the ill-fated Captain Brown. Other Spectrum officers can often be seen taking orders from Blue, hence his high placement on this list. Out of the four main Spectrum characters on the show, Blue is the only American one.

Captain Scarlet

Spectrum's indestructible Captain Scarlet is the main character in the show, and nine out of ten times it is Scarlet who foils the Mysteron's plots and ploys.

NB: Note that the rest of the captains are little more than extras within the show, so the order they are listed doesn't necessarily reflect the pecking order within Cloudbase.

Captain Magenta

The eager-to-please Captain Magenta mans Spectrum's radar station and is seldom seen outside of Cloudbase. (unsurprising considering his nice pink suit) Perhaps his most notable appearance was during Captain Blue's dreamed invasion of Cloudbase by Mysteron forces.

Captain Ochre

Captain Ochre is a very minor character indeed, but is sometimes seen co-ordinating security operations and driving the Spectrum high-security vehicles.

Captain Grey

Mistaken for Captain Black by many a newbie Captain Scarlet geek, Captain Grey is a mostly un-noteworthy character with no real story lines or parts to play other than sitting around drinking coffee in Cloudbase's observation lounge.

Captain Brown (deceased)

Short-lived Captain Brown was Captain Scarlet's first partner, but was killed during the first episode along with Captain Scarlet, and then brought back as a Mysteron, who explodes as an assassination attempt on the World President.

Captain Indigo (deceased)

Another short-lived character, Indigo appeared in only one episode, Spectrum Strikes Back. He is shot by Captain Black and turned into a Mysteron and later becomes the first victim of the Mysteron Gun at the hands of Captain Scarlet.

Doctor Fawn

Manning the infirmary of Cloudbase, the somewhat underused Doctor Fawn helps Captain Scarlet back to health after his fall from the mile-high building, and pronounces him dead during Captain Blue's dream of Cloudbase's destruction at the hands of the Mysterons after the expert advice of his masquerading assistant, Captain Black.

Lieutenant Green

Junior officer of Cloudbase and Colonel White's PA, Green also acts as the communications officer on Spectrum's air born command post and mans the comms post in the base's control centre, where he handles both internal and external communication, and instructs the Angels when to launch. As the fourth main Spectrum character on the show, Green is sometimes allowed to go out on missions with Captains Blue and Scarlet. (if he's a good boy)

The Angels

The Angels, the only female members of Spectrum on Cloudbase, pilot the Angel reconnaissance and combat aircraft. As was typical with science fiction of this era, the Angels are pretty much portrayed as slightly-silly, fashion-crazed females who are mainly there to look good. (as far as puppets go) The angels are codenamed:

Spectrum vehicles

Spectrum has a wide variety of land and air-based vehicles to aid in their fight against the Mysterons:

Spectrum Pursuit Vehicle (SPV)

The most often-used Spectrum land vehicle, the SPV is not very far at all from being a fully-fledged battle tank. Moving on caterpillars for all-terrain situations, the SPV can move at deceptively high speeds. Of course, high-speed pursuits are highly dangerous in crowded cities and winding country roads, so the driver and passenger actually sit with their back to the front of the vehicle, and use a periscope to see what's ahead. The SPV is controlled by handlebars rather than a steering wheel.
The SPV isn't just a fast tractor, as it contains an arsenal of surface-to-surface missiles. For the daring officer, the driver and passenger seats of the SPV can be projected out the side of the vehicle, allowing for manual shooting of pursuees. Armour plating on the chassis of the SPV ensures any return fire will be largely ineffective.
SPVs are stationed throughout the world in secret locations, (mostly sheds in countryside gas stations) and can be requested for use by any Spectrum officer carrying a valid pass.

Spectrum Saloon Vehicle

Used more often in the earlier episodes, the Saloon Vehicle is really just a very fast two-seater red road car with a more aerodynamic shape and the Spectrum insignia on the side of the body. It was a saloon vehicle whose tyre burst causing the deaths of Captain Scarlet and Captain Brown in the first episode.

High-security Vehicle

A medium ground between the SPV and the saloon vehicle, the high-security vehicle has neither the SPVs bulk nor the relative flimsiness of the saloon. The high-security vehicle is used to transport important people who are at risk from Mysteron assassination. The only downside with this vehicle is that it is very conspicuous, and it is probably for this reason that it only gets used once or twice during the series, usually being neglected in favour of a converted petrol tanker.


Spectrum's air born command post, Cloudbase accommodates all of the personnel from the show, the Angel aircraft and several auxiliary aircraft, that take off from a runway on Cloudbase's deck. Kept afloat by an array of downward-thrust jets, Cloudbase can make use of forward propulsion to change its geographic location during times of alert.
As well as the runway, Cloudbase itself features all the facilities one could expect to find in a military command centre, including a control centre, a lounge for the officers and an infirmary.

Angel reconnaissance and combat aircraft

These white aircraft flown by The Angels are souped-up fighter jets as used by the World Army. As well as the ability to fly at speeds of up to mach seven, these aircraft are armed with laser cannons and an array of missiles to target both land and air-based targets. Angel aircraft are also used to survey large areas of land (such as deserts) when a helicopter would be too slow.

NB: There are other spectrum aircraft that are un-noteworthy except for their blue and silver Spectrum livery. These include Spectrum search and rescue helicopters and Spectrum passenger airliners for diplomatic missions.

Non-standard-issue equipment

The Mysteron Detector

During the treatment of Captain Scarlet after his fall from the mile-high building, it was found that people who have been taken over by the Mysterons are impervious to X-rays. (that is, attempted X-rays of Mysterons develop into ordinary black-and-white photographs) The Mysteron Detector is in effect a hand-held X-ray machine that immediately prints out the results, much like a Polaroid camera. It immediately proved to be a success as a Mysteron impostor was inadvertently detected during its initial demonstration

The Mysteron Gun

It was discovered early on in the series that Mysterons can only be destroyed with intense levels of electricity and so this short-range weapon was developed. Essentially it is a high-power cattle prod that makes a sound similar to one made when tuning a shortwave radio when it is in use and results in the instant death of the target. The Mysteron Gun is grossly underused however, with most Mysterons inexplicably dying in explosions or car accidents. (which have nothing to do with electricity, unless these Mysterons die of friction burns or some such)


There are only two often-used codewords used by Spectrum officers, those being 'SIG' (Spectrum Is Green) to mean 'affirmative' or that everything is OK. The opposite to this is the never actually used 'SIR'. (Spectrum Is Red)

Interesting Note

It is often stated during the series that Spectrum was set up in response to The Mysterons and their declaration of war on Earth, however, at the beginning of the first episode Captain Black is clearly in Spectrum uniform for the Mars exploration mission, when at the time the existence of the Mysteron race was not even known.

Relevant websites:

Spec"trum (?), n.; pl. Spectra (#). [L. See Specter.]


An apparition; a specter.


2. Opt. (a)

The several colored and other rays of which light is composed, separated by the refraction of a prism or other means, and observed or studied either as spread out on a screen, by direct vision, by photography, or otherwise. See Illust. of Light, and Spectroscope.


A luminous appearance, or an image seen after the eye has been exposed to an intense light or a strongly illuminated object. When the object is colored, the image appears of the complementary color, as a green image seen after viewing a red wafer lying on white paper. Called also ocular spectrum.

Absorption spectrum, the spectrum of light which has passed through a medium capable of absorbing a portion of the rays. It is characterized by dark spaces, bands, or lines. -- Chemical spectrum, a spectrum of rays considered solely with reference to their chemical effects, as in photography. These, in the usual photogrophic methods, have their maximum influence at and beyond the violet rays, but are not limited to this region. -- Chromatic spectrum, the visible colored rays of the solar spectrum, exhibiting the seven principal colors in their order, and covering the central and larger portion of the space of the whole spectrum. -- Continous spectrum, a spectrum not broken by bands or lines, but having the colors shaded into each other continously, as that from an incandescent solid or liquid, or a gas under high pressure. -- Diffraction spectrum, a spectrum produced by diffraction, as by a grating. -- Gaseous spectrum, the spectrum of an incandesoent gas or vapor, under moderate, or especially under very low, pressure. It is characterized by bright bands or lines. -- Normal spectrum, a representation of a spectrum arranged upon conventional plan adopted as standard, especially a spectrum in which the colors are spaced proportionally to their wave lengths, as when formed by a diffraction grating. -- Ocular spectrum. See Spectrum, 2 (b), above. -- Prismatic spectrum, a spectrum produced by means of a prism. -- Solar spectrum, the spectrum of solar light, especially as thrown upon a screen in a darkened room. It is characterized by numerous dark lines called Fraunhofer lines. -- Spectrum analysis, chemical analysis effected by comparison of the different relative positions and qualities of the fixed lines of spectra produced by flames in which different substances are burned or evaporated, each substance having its own characteristic system of lines. -- Thermal spectrum, a spectrum of rays considered solely with reference to their heating effect, especially of those rays which produce no luminous phenomena.


© Webster 1913.

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