pointing reference: the other instruments all align themselves to the EIT images. Focus adjustment is achieved by thermal expansion: the internal survival heaters (found in most spaceborne instruments) are used to achieve microscopic changes in the size of the telescope structure and hence the mirror spacing. EIT was originally allocated only about 1 kbit/s of data—about the same speed as a 110 baud teletype—but after its utility became clear much more telemetry bandwidth was allocated to it. Related instruments The technology in EIT is based on prototype instruments that were flown on the sounding rocket payloads MSSTA and NIXT. The first multilayer telescope to image the full disk of the Sun in EUV was flown by A.B.C. Walker and team in 1987. The TRACE, STEREO, and Proba-2 spacecraft (launched in 1998, 2006, and 2009, respectively) carry similar multilayer imagers, as does the Solar Dynamics Observatory mission. External links Latest EIT full-field images References Solar and Heliospheric Observatory Space telescopes Extreme ultraviolet telescopes Telescope instruments