1.1 Image quality: FD-TXI: The optical train (primary mirror, secondary mirror, TXI flat mirrors, entrance aperture and focal plane filters) shall have a 90% encircled energy of <2" and a FWHM n.t.e. TBD". HR-TXI: The optical train (primary mirror, secondary mirror, TXI flat mirrors, entrance aperture and focal plane filters) shall have a 90% encircled energy of <0.02" and a FWHM n.t.e. TBD". (NB: Pixel sizes for the instruments are approximately 1, 0.01'' respectively) 1.2 Multilayer coatings: 1.2.1 Bandpass: Primary and secondary mirrors to have broad-band (170-220A, TBR) coatings. 1.2.2 Reflectivity: Primary and secondary mirrors to have a peak reflectivity >25% at TBD lambda. 1.2.3 Uniformity: 1.2.4 TXI mirrors to have..?? 1.3 Spectroscopy: 1.3.1 Mechanism Times (all include settling times): 22.214.171.124 Changeover time, TXI-broadband: 5 minute (TBR), including settling 126.96.36.199 TXI small-lambda (0.5A ~ 0.045 radians) motions: 1 second (TBR) 188.8.131.52 TXI large-lambda (from any lambda to any other, approx. 0.15rad): 5 seconds (TBR) 1.3.2 Mechanism Accuracy: TXI smallest steps are 0.1A (~ 0.009rad). 1.3.3 Mechanism Repeatability: TXI lambda repeatablity to within 0.1A. 1.3.4 Mechanism range: TXI range is 170-220A (TBR) ~ 8degrees, or 0.15 rads 1.3.5 Mechanism directionality: TXI must be capable of slewing up and down in wavelength. 1.4 Telescope co-alignments (see note below on required offsets): FD-TXI to MR-TXI: 100'' on orbit MR-TXI to HR-TXI: 10'' on orbit Magnetograph to FD-TXI: 30'' [TBR] on orbit offsets: The telescopes are not strictly co-aligned. There is an offset imposed by the requirement that the gaps in the CCDs caused by butting them do not overlap. Thus, the MR-TXI CCD image falls 250 +/- 100 FD-TXI pixels above the FD-TXI butt line. Likewise, the HR-TXI image falls 200+/- 200 MR-TXI pixels above the MR-TXI butt line. 1.5 Optical Alignments: 1.5.1: Each telescope's optical system must be capable of achieving final alignment in orbit consistent with the required image quality as defined in 1.1. 1.6 Focus Requirements: 1.6.1: Each telescope's optical system must be capable of achieving final focus in orbit consistent with the required image quality as defined in 1.1. Both coarse and fine focus must be provided for. 2. FILTERS: 2.1 Focal Plane Filters: Shall transmit not less than 80% of the incident x-ray flux, over the range of 170-220A. 3. LIGHT REJECTION 4.1 Visible light rejection at the focal plane: variable from 10*4 to 10*14 by using different focal plane filter combinations (requires 2 filter wheels with at least one open position on each). 4. EXTENDABLE BENCH: 4.1 The bench must be capable of extending to a final length of 30m, and must be capable of fitting inside a Delta-2 shroud at launch. The bench must be of sufficient stiffness to enable the focus and alignment of the telescopes to be maintained over periods of not less than 30 days. 5. CCD REQUIREMENTS 5.1 Minimum integration time: 0.1s 5.2 Maximum integration time: 200s 5.3 Detector size: 4Kx4K (or 2Kx4K, buttable) 5.4 Read noise requirement: TBD 5.5 Dark count requirement: TBD 5.6 Simultaneous start times: Any combination of science CCDs must be capable of simultaneous start times (to within 0.1 TBR seconds). 6. CALIBRATIONS 6.1 Ground Calibrations: 6.2 In-flight Calibrations: 6.2.1 CCD Dark frames 6.2.2 CCD Flat fields 6.2.3 Throughput vs. time 184.108.40.206 Filter throughput vs. time 220.127.116.11 Mirror reflectivity vs. time 18.104.22.168 CCD sensitivity vs. time 7. ISPI REQUIREMENTS 8. MAGNETOGRAPH REQUIREMENTS 9. POINTING REQUIREMENTS: 9.1 Absolute knowledge: 9.2 Relative: 9.3 Max. offset from Sun Center: 9.4 Separate Telescope Offsets: there are no requirements that the three telescopes be capable of viewing different FOVS. 9.5 Focal plane must be capable of following a feature at the solar equator for exposures between 1-200 seconds. (2km/sec at solar eq => 0.3 pixel/second in HR-TXI, 0.03 pixel/second in MR-TXI, and 0.003 pixel/second in FD-TXI, assuming 12 micron pixels ). 10. TIMING REQUIREMENTS: 10.1 Absolute timing: to within 1 TBR second 10.2 Relative timing: to within 0.1 TBR second B. HIREX DERIVED ENGINEERING REQUIREMENTS C. HIREX ENGINEERING DESIGN DRIVERS 1. All optics must be easily accessible/replaceable. Replacement includes alignment/focus. 2. Weight reduction is a primary consideration.
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