Instruction Manual

Deﬁ nition of Terms

Prominences — H-a emissions projecting beyond the limb of the sun, consisting of complex clouds or

streamers of ionized hydrogen above or in the Chromosphere.

Filaments - Prominences seen against the face of the sun, appearing as long narrow dark streamers or

diffuse dark areas.

Active Region - Active regions are the result of enhanced magnetic ﬁ elds and appear darker than the

surrounding areas with a roughly circular shape. Active regions show plage, sunspots, and ﬂ ares.

Plage - Patchy H-a brightening on the solar disk, usually found in or near active regions, which can last for

several days. These are found in areas of nearly vertical emerging or reconnecting magnetic lines.

Sunspots - Spots of varying size usually consisting of a dark central region (umbra) and a lighter halo

consisting of many short ﬁ ne ﬁ brils (penumbra).

Flares - A sudden eruption of energy in the solar atmosphere lasting minutes to hours, from which

radiation and particles are emitted.

Chromosphere - An incandescent, transparent layer of gas, primarily hydrogen, several thousand miles

in depth, lying above and surrounding the Photosphere of the Sun and beneath the transition region of the

Corona.

FOV - Field of View. This describes, in degrees, the area of sky one can see when looking through the

eyepiece.

OTA - Optical Tube Assembly. This is the main body of a telescope.

H-a - A wavelength of light at 656.3nm or 6562.8 Angstroms

(1nm = 1 billionth of a meter)

Angstrom - A unit of measurement for the wavelength of light.

(1A= O.1nm)

Bandpass - A ﬁ lter’s bandpass tells how wide a region of the light spectrum is transmitted around the

primary wavelength. The narrower the bandpass, the more surface detail becomes visible on the Sun.

Coronado can further narrow the bandpass of your primary ﬁ lter by adding a matched ﬁ lter of the same

size to the objective or by placing a smaller secondary ﬁ lter in the optical train. The term “double stacking”

is used to describe this process.

E.R.F. - Energy Rejection Filter. Prevents UV and IR light from entering the telescope.

Etalon - The heart of a Coronado ﬁ lter. Composed of optics with tolerances 4 times tighter than those used

in the Hubble telescope.