Editing TRACE (section)

=== TRACE Imaging Telescope ===
The telescope is of [[Cassegrain reflector|Cassegrain design]], {{cvt|1.6|m}} long with an aperture of {{cvt|30|cm}}. The focal length is {{cvt|8.66|m}}. The field of view of the telescope is 8.5 x 8.5 [[Minute and second of arc|arcminutes]] with a spatial resolution of one arcsecond. The light is focused on a 1024 x 1024 element CCD detector (0.5 arcseconds/[[pixel]]). The temporal resolution of the instrument is less than 1 second, although the nominal temporal resolution is 5 seconds. Exposure times for observations range between 2 ms and 260 seconds. The primary and secondary mirrors have normal-incidence coatings specially designed for EUV and UV observations which divide the mirrors into quadrants. These segmented coatings are designed to provide identically sized and perfectly coaligned images. Which mirror quadrant is used for an observation is determined by the position of a quadrant selector shutter mechanism, positioned behind the entrance aperture. Three of the mirror coatings provide for observations in specific [[iron]] emission bands: Fe IX (central wavelength/bandwidth: 17.3 nm/0.64 nm); Fe XII (19.5 nm/0.65 nm); and Fe XV (28.4 nm/1.07 nm). The final mirror coating allows broadband observations in the ultraviolet (centered on 500 nm). Further selection of observations in the UV can be made through the use of a filter wheel, mounted in front of the CCD. The filter wheel permits continuum observations (170 nm/20 nm) as well as observations in emission bands for C (carbon) I and Fe II (160 nm/27.5 nm), C IV (155 nm/2 nm), and H (Hydrogen) I (Lyman-alpha) (121.6 nm/8.4 nm). The TRACE primary mirror assembly is based on primary mirror support assemblies used in [[SWATH]], a small explorer developed for the [[United States Air Force|U.S. Air Force]], and [[NIXT]], a set of rocket flights flown by the Smithsonian Astrophysical Observatory (SAO) five times between 1983 and 1993. Many of the designs and some of the space flight hardware from the MDI instrument on [[Solar and Heliospheric Observatory]] (SoHO) was also used.