Telescope:

45 cm, f/15 Ritchey-Chrétien Cassegrain

Spectrographs:

Echelle (115 nm to 198 nm and 180 nm to 320 nm)

Apertures:

3" and 10" by 20" image quality 2"

Resolution:

1.8×10⁴  corresponding to 0.008 nm @ 140 nm (17 km s^-1)

1.3×10⁴ corresponding to 0.017 nm @ 260 nm; (20 km s^-1)

27° in low resolution mode @ 150 nm

40° in low resolution mode @ 270 nm

Cameras:

SWP (115-197 nm)

sensitivity: 2×10 ^-15 ergs s^-1 cm^-2 Å^-1

LWP (175-330 nm)

sensitivity: 1×10^-15 ergs s^-1 cm^-2 Å^-1

LWR (175-330 nm)

sensitivity: 2×10^-15 ergs s^-1 cm^-2 Å^-1

SWR

Never operational

FES #1

Fine-Error-Sensor #1 has not been used in operations.

FES #2

Fine-Error-Sensor #2 has been used for fine guidance throughout the mission. It has also been important as a photometer to measure the optical brightness of the sources observed. In 1991 scattered light entering the telescope required a revision of guidance procedures and affected its photometric performance.