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| ====== Telecon 20180221 ====== | ====== Telecon 20180221 ====== | ||
| - | Attending: | + | Attending: |
| - | Notes by : \\ | + | Notes by : Qi \\ |
| === Agenda=== | === Agenda=== | ||
| * Attitude Control and Reconstruction Requirements (Wrap up) | * Attitude Control and Reconstruction Requirements (Wrap up) | ||
| + | * Tentative baseline: control = 1' (3 sigma) over 1 spin period; reconstruction = 1" (3 sigma) | ||
| * Last week's presentation from Jacques: [[https:// | * Last week's presentation from Jacques: [[https:// | ||
| - | * Last week's images from Kris:| {{:: | + | * Last week's images from Kris: | {{:: |
| - | * Telescope I+T (Tomo) | + | * {{:: |
| + | * Telescope I+T (Tomo and Bill) | ||
| * {{:: | * {{:: | ||
| + | * {{:: | ||
| * Instrument I+T (Bill J.) | * Instrument I+T (Bill J.) | ||
| === Notes === | === Notes === | ||
| + | * Attitude Control and Reconstruction Requirements (Wrap up) | ||
| + | * The discussion was from last week: based on cross scan sampling, Jacques argued that increasing precession period T_prec is an potential solution, in order to achieve better sky coverage | ||
| + | * Kris did not agree | ||
| + | * Kris's updates: | ||
| + | * figures show the high-resolution (highest frequency beam) hits number of sky coverage, assuming precession angle 30 deg and spin spin angle 65 deg. | ||
| + | * Two cases were studied, fast (48 hrs) and slow (7 hrs) | ||
| + | * it's shown that hits are dense on the edge of " | ||
| + | * for slow precession, the distinction between edges and inner parts is more obvious | ||
| + | * color is in log scale, red is much more dense than blue | ||
| + | * color scales in slow and fast are not same; the maxium in 48 hrs is a factor of ~4 compared to 7 hrs | ||
| + | * Kris's conclusion: short (fast) precession is better | ||
| + | * Shaul: 1 arcmin in 3 sigma in single spin rate is based on fast precession | ||
| + | * Kris: many motions of PICO are much faster than Planck, we need to be careful. Someone studing WMAP pagers is a good thing to do. | ||
| + | * Shaul: we need to be careful, star tracker; In optical astronomy, they don’t scan fast, so it’s trivial for them. | ||
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| + | * Telescope I+T (Tomo） | ||
| + | * pg24 | ||
| + | * reminder, introduction about what Tomo talks today | ||
| + | * fully integrated test when it’s cold | ||
| + | * optics only; tests one can possibly imagine | ||
| + | * pg28 | ||
| + | * purpose: mirror shape | ||
| + | * two spacial scales: large ,small scales | ||
| + | * Large scals: you cannot probe smaller than the space between markers | ||
| + | * Short scales: very small scales | ||
| + | * A combination of both scales; blue table | ||
| + | * “Cold” means some cold temperature, | ||
| + | * Minimal tests for PICO: Photogrammetry and Interferometry; | ||
| + | * CMM: surface, not sure if there is facility big enough for PICO mirror | ||
| + | * Shaul: mirror vendor, whatever lab who puts the instrument together; whoever provides mirrors, they would CMM warm; CMM is part of the cost buying the mirror; I & T is beyond vendor level. | ||
| + | * Tomo: for space mission, it’s common you repeat measurements even vendors have done so. | ||
| + | * Brian: normally, | ||
| + | * Tomo: different models, e.g. ground model, flight model; you can do tests in first few models, then you trust (vendors). | ||
| + | * pg29 | ||
| + | * Tomo: partly a comment, partly a question | ||
| + | * after the characterization, | ||
| + | * pre-flight: sub and full level tests; outputs: performance verification and mirror shapes | ||
| + | * inflight: beam calibration; | ||
| + | * post-flight: | ||
| + | * What did Planck use to get beam? What are the key information? | ||
| + | * Kris: LFI used Grasp model; HFI used planet measurements; | ||
| + | * Beam size is important because couple to focal plane; in part of scanning. Sometimes more reliable on GRASP model. | ||
| + | * Tomo: future mission should have tighter requirement for signal-to-noise; | ||
| + | * Kris: Any test before flight is valuable. | ||
| + | * Shaul: not clear what Planck did was used and useful in terms of tests. | ||
| + | * Kris: not sure if there is a short path compared to Planck. | ||
| + | *Pg30 | ||
| + | * Tomo: it’s very important to characterize feed beam. For Planck, corrugated horns are classic and thus did not need more attention; PICO could use something else. | ||
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