TRACE Imaging Telescope

The TRACE imaging telescope is the sole science instrument on the spacecraft. Its primary science objectives are to: (1) follow the evolution of magnetic field structures from the solar interior to the corona; (2) investigate the mechanisms of the heating of the outer solar atmosphere; and, (3) determine the triggers and onset of solar flares and mass ejections.
The telescope is of Cassegrain design, 1.6 m long with an aperture of 30 cm. The focal length is 8.66 m. The field of view of the telescope is 8.5 x 8.5 arc-minutes with a spatial resolution of one arc-second. The light is focused on a 1024 x 1024 element CCD detector (0.5 arc-seconds/pixel). The temporal resolution of the instrument is less that 1 s, although the nominal temporal resolution is 5 s. Exposure times for observations range between 2 ms and 260 s.
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 I and Fe II (160 nm/27.5 nm), C IV (155 nm/2 nm), and H 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 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 SOHO was also used.

TRACE成像望远镜是搭载在航天器上的唯一科学仪器。其主要科学目标包括：(1) 跟踪太阳内部到日冕的磁场结构演变；(2) 研究外部太阳大气加热的机制；(3) 确定太阳耀斑和物质抛射的触发和爆发时刻。该望远镜采用卡塞格林式设计，全长1.6米，口径30厘米，焦距8.66米。望远镜视场为8.5 x 8.5角分，空间分辨率为1角秒。光线聚焦于一个1024 x 1024像素的CCD探测器（像素分辨率为0.5角秒/像素）。仪器的时间分辨率为小于1秒，而标准时间分辨率为5秒。观测曝光时间介于2毫秒到260秒之间。主镜和副镜表面涂有针对极紫外和紫外观测的普通入射涂层，将镜子分为四个象限。这些分段涂层旨在提供尺寸相同且完美对齐的图像。用于观测的镜子象限由位于入口孔径后方的象限选择快门机制的位置决定。其中三个象限的涂层用于特定铁发射带的观测：Fe IX（中心波长/带宽：17.3纳米/0.64纳米）；Fe XII（19.5纳米/0.65纳米）；Fe XV（28.4纳米/1.07纳米）。最终的镜面涂层允许在紫外波段进行宽带观测（中心波长为500纳米）。通过安装在CCD前方的滤光轮，可以进一步选择在紫外波段的观测。滤光轮允许进行连续观测（170纳米/20纳米）以及C I和Fe II（160纳米/27.5纳米）、C IV（155纳米/2纳米）和H I（莱曼-α）发射带的观测。TRACE主镜组件基于SWATH（一种为美国空军开发的微小探测器）和NIXT（史密森天体物理观测站（SAO）在1983年至1993年间进行的五次火箭飞行任务）所使用的主镜支撑组件。SOHO上的MDI仪器的设计和一些空间飞行硬件也被大量采用。