Campuses:
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| imagerteleconnotes20171017 [2017/10/17 14:03] – hanany | imagerteleconnotes20171017 [2017/10/18 09:42] (current) – kyoung | ||
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| ====== Telecon 20171017 ====== | ====== Telecon 20171017 ====== | ||
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| __Agenda: | __Agenda: | ||
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| __Notes:__ | __Notes:__ | ||
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| + | Open Dragone: optical system + noise model + focal plane options (Young) | ||
| + | * Size of pixel defined on lowest or middle frequency band. | ||
| + | * middle band means smaller pixel, higher sensitivity | ||
| + | * 10 dB edge taper + middle band size, overall the best in terms of mapping speed | ||
| + | * lowest band has 4.8 dB edge taper | ||
| + | * edge taper is at 4K stop | ||
| + | * Using 10 dB at middle of band moving forward. | ||
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| + | * For Open Dragone, the DLFOV is small. The outer area of the focal plane is not usable for high frequency, thus it’s hard to trade low -frequency detectors for more high-frequency detectors. | ||
| + | * We don’t know what we need for low frequency, it depends on the synchrotron structures. | ||
| + | * Plan is to optimize mirror shapes to increase ~150 GHZ DLFOV so trading low sensitivity for high sensitivity is an option. | ||
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| + | * Open Dragone Optics | ||
| + | * V3.D: focal plane further from stop, linearly 10% more focal plane compared to baseline | ||
| + | * looks good, has room for mechanical structure of focal plane | ||
| + | * Karl is working on coma correction to this telescope, and hopefully we will have larger DLFOV **(AI)** | ||
| + | * V4: 10% less DLFOV compared to baseline. | ||
| + | * sensitivity calculation uses edge taper defined as lowest band, can be done using middle band | ||
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| + | Large-aperture Cross Dragone (Wen) | ||
| + | * Follow-up to matrix from previous week. Now we have a baffled, large cross dragone. | ||
| + | * Reminder: Why 50cm? De-scoped to save cost, if imager + spectrometer is emplemented. | ||
| + | * Still questions as to whether just 140cm -- 50 cm saves cost. | ||
| + | * Idea here is to provide options to cost and be decided on by the EC. | ||
| + | * Cross Dragone has large DLFOV if not limited by vignetting (blockage, mirror sizes etc) | ||
| + | * current case is limited by vignetting and blockage, not image quality. | ||
| + | * unlike Open Dragone case, we can trade detectors at low frequency for high-frequency detectors more easily | ||
| + | * ~ 3K detectors (Open) | ||
| + | * F number: 1.5 (Open) | ||
| + | * more detectors + larger F#, means Cross Dragone has larger focal plane | ||
| + | |||
| + | * We have filled the matrix of telescope categories | ||
| + | * optics design is wrapping up. Polishing will be done to improve sensitivities. | ||
| + | * the large/ | ||
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| + | Scan (Kris) | ||
| + | * Simulation | ||
| + | * note WMAP Q/U map in V band; Probe with alpha = 22 deg, beta = 73 deg, is close to WMAP | ||
| + | * fast spin + different precession (fast, slow, very slow) | ||
| + | * for T spin 20s (3 rpm) is fast, Kris do 1 rpm **(AI)** | ||
| + | * slowest precession, more non-smooth features, higher resolution needed | ||
| + | * LiteBird & Core use same convention of alpha and beta, Kris will change his definition | ||
| + | * The simulations are the average over 1 year | ||
| + | * simulating over other different periods will be very useful, give more opportunities to look into the scanning. | ||
| + | * Jacques: maps with no holes over week timescales are useful. | ||
| + | * Kris will do two-week simulation **(AI)** | ||
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| + | Scanning strategy | ||
| + | * Julian: 6 + 1 parameters; precession angle alpha, spin angle beta, 3 rotation rates (spin, precession, HWP), radius of L2 orbit, + data (or sample) rate. | ||
| + | * Jacques will lead to make table of scan drivers, wants, and evaluation metrics in wiki **(AI)** | ||
| + | * Shaul to make table of hardware or engineering limits on 6 + 1 parameters **(AI)** | ||
| + | * Brian: there may not be many options of the L2 orbits | ||
| + | * there could be, we need more information input from project | ||
| + | * Jacques: Planck had radius L2 = 300,000 km, small. Needed 380 kg fuel for insertion. | ||
| + | * Brian and Amy to check details of L2 orbit **(AI)** | ||
| + | * Amy told Shaul that we will probably have a steerable antenna for tele-communication; | ||
| + | * Kris: demonstration of full scan + systematics + map making is also important | ||
| + | * Julian: Agree, the machinery exists to do these sims. They need to be in time domain. | ||
| + | * Shaul’s comments on this scan parameters study: 1) optimization of parameters; 2) systematics given parameters | ||
| + | * When mapping + noise correlation? | ||
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